Bartlett, Nancy L.

Introduction: As previously reported, the combination of brentuximab vedotin with doxorubicin, vinblastine and dacarbazine (A+AVD) demonstrated a statistically significant improvement in modified progression free survival (modified PFS) compared with doxorubicin, bleomycin, vinblastine and dacarbazine (ABVD) in patients with newly diagnosed Stage III or IV classical HL in the phase 3 ECHELON-1 trial (NCT01712490). The benefit of A+AVD in the ITT population observed in the primary analysis was maintained at 3-years median follow-up [3-year PFS: A+AVD: 83.1% (79.9-85.9), ABVD: 76% (72.4-79.2)] and appears independent of interim PET status, disease stage, and prognostic risk factors. Here we present the efficacy and safety results of longer follow-up at a median 43.3 months. Methods: Newly diagnosed patients with Stage III or IV cHL were randomized 1:1 to receive A+AVD (n=664) or ABVD (n=670) intravenously on days 1 and 15 of each 28-day cycle for up to 6 cycles. The primary endpoint of the study was modified PFS per independent central review. The present follow-up PFS analysis is exploratory and per investigator assessment, with a cutoff date of June 17th, 2019. Patients with ongoing peripheral neuropathy (PN) at end of treatment were followed for resolution or improvement (defined as improved by ≥1 grade from worst grade as of the latest assessment) during the post-treatment follow-up period. Results: With a median follow-up of 43.3 months, the 42-month PFS per investigator for all patients was 82.4% (95% CI, 79.1-85.2) on the A+AVD arm and 76.2% (95% CI, 72.6-79.4) on the ABVD arm [overall HR 0.697 (95% CI, 0.547-0.890)]. Exploratory subgroup analyses of PET2(+) and PET2(-) patients showed a treatment effect in favor of A+AVD. The 42-month PFS in PET2(-) patients was 85.0% (95% CI, 81.6-87.7) for A+AVD and 79.6% (95% CI, 75.9-82.8) for ABVD [overall HR 0.695 (95% CI, 0.526-0.919)]; in PET2(+) patients 42-month PFS was 68.3% (95% CI, 54.5-78.7) for A+AVD and 51.5% (95% CI, 38.2-63.4) for ABVD [overall HR 0.552 (95% CI, 0.308-0.989)]. Upon continued follow-up, 81% (356/442) of patients with PN in the A+AVD arm had either complete resolution (64%, 283/442) or improvement (17%, 73/442) of their PN events compared with 83% (236/286) with either complete resolution (74%, 212/286) or improvement (8%, 24/286) in the ABVD arm. Among patients with ongoing PN after continued follow-up, the majority were Grade 1/2 events, with 89% (141/159; 59% Grade 1) and 95% (70/74; 65% Grade 1) on the A+AVD and ABVD arms, respectively. Overall survival data are not yet mature; per protocol, the final analysis will be performed after 112 deaths have occurred. Additional follow-up at an estimated median of ~4 years, including data from prespecified subgroups, will be presented. Conclusions: With a median follow-up of 43.3 months, A+AVD continues to provide a robust, durable benefit for patients with previously untreated Stage III or IV cHL compared with ABVD; the benefit is evident regardless of patient status at interim PET [PET2(+) or PET2(-)] and without the need for treatment intensification. PN continued to completely resolve or improve in patients on the A+AVD and ABVD arms. Together, these data further support the clinical advantages of A+AVD versus ABVD as treatment for patients with previously untreated Stage III or IV cHL. Disclosures Bartlett: Affimed Therapeutics: Research Funding; Bristol-Myers Squibb: Research Funding; Celgene: Research Funding; Dynavax: Research Funding; Forty-Seven: Research Funding; Genentech: Research Funding; Gilead: Research Funding; Immune Design: Research Funding; Janssen: Research Funding; Kite Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Medimmune: Research Funding; Merck: Research Funding; Millennium: Research Funding; Novartis: Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Research Funding; Seattle Genetics, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Straus:Elsevier (PracticeUpdate): Consultancy, Honoraria; Hope Funds for Cancer Research: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Consultancy, Honoraria. Dlugosz-Danecka:Servier: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Macrogenomics: Research Funding; Roche: Honoraria, Speakers Bureau; Janssen: Consultancy, Honoraria, Speakers Bureau. Illes:Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Seattle Genetics: Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees. Feldman:Takeda: Honoraria, Speakers Bureau; Celgene: Honoraria, Research Funding, Speakers Bureau; Cell Medica: Research Funding; Amgen: Research Funding; Viracta: Research Funding; Bayer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Kite Pharma: Honoraria, Other: Travel expenses, Speakers Bureau; Janssen: Honoraria, Speakers Bureau; Pharmacyclics: Honoraria, Other: Travel expenses, Speakers Bureau; Pfizer: Research Funding; Portola Pharma: Research Funding; Roche: Research Funding; Eisai: Research Funding; Corvus: Research Funding; Roche: Research Funding; AbbVie: Honoraria, Other: Travel expenses, Speakers Bureau; Seattle Genetics: Consultancy, Honoraria, Other: Travel expenses, Speakers Bureau; Kyowa Hakko Kirin: Research Funding; Trillium: Research Funding. Smolewski:Roche: Other: Travel Expenses. Savage:Seattle Genetics, Inc.: Consultancy, Honoraria, Research Funding; BMS, Merck, Novartis, Verastem, Abbvie, Servier, and Seattle Genetics: Consultancy, Honoraria. Walewski:Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Expenses, Research Funding; Takeda: Honoraria, Research Funding; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Servier: Honoraria; Gilead: Other: Travel Expenses; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Zinzani:Portola: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Immune Design: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sandoz: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen-Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celltrion: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Consultancy; Eusapharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; MSD: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Verastem: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Kyowa Kirin: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; TG Therapeutics: Honoraria, Speakers Bureau. Hutchings:Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Expenses, Research Funding; Genmab: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel Expenses, Research Funding; Novartis: Research Funding; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Expenses, Research Funding. Radford:AstraZeneca: Equity Ownership, Research Funding; Novartis: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; ADC Therapeutics: Consultancy, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria; GSK: Equity Ownership. Munoz:AstraZeneca: Speakers Bureau; Kite Pharma: Consultancy, Research Funding, Speakers Bureau; Pharmacyclics LLC an AbbVie Company: Consultancy, Research Funding, Speakers Bureau; Gilead: Consultancy, Speakers Bureau; Fosunkite: Speakers Bureau; Kyowa: Consultancy, Honoraria, Speakers Bureau; Bayer: Consultancy, Speakers Bureau; Seattle Genetics: Consultancy, Honoraria, Research Funding; Celgene: Research Funding; Portola: Research Funding; Incyte: Research Funding. Kim:Roche: Research Funding; Kyowa-Kirin: Research Funding; Novartis: Research Funding; J&J: Research Funding; Mundipharma: Research Funding; Celltrion: Research Funding; Donga: Research Funding. Advani:Cell Medica, Ltd: Consultancy; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Research Funding; Kura: Research Funding; Infinity Pharma: Research Funding; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; Celmed: Consultancy, Membership on an entity's Board of Directors or advisory committees; Autolus: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agensys: Research Funding; Stanford University: Employment, Equity Ownership; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Consultancy, Research Funding; Kyowa Kirin Pharmaceutical Developments, Inc.: Consultancy; Regeneron: Research Funding; Millennium: Research Funding; Janssen: Research Funding; Roche/Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead Sciences, Inc./Kite Pharma, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees; Forty-Seven: Research Funding; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees. Ansell:Mayo Clinic Rochester: Employment; Affimed: Research Funding; Mayo Clinic Rochester: Employment; Trillium: Research Funding; Affimed: Research Funding; Seattle Genetics: Research Funding; Trillium: Research Funding; Trillium: Research Funding; Affimed: Research Funding; Bristol-Myers Squibb: Research Funding; Bristol-Myers Squibb: Research Funding; LAM Therapeutics: Research Funding; Regeneron: Research Funding; Affimed: Research Funding; Trillium: Research Funding; Mayo Clinic Rochester: Employment; Regeneron: Research Funding; Bristol-Myers Squibb: Research Funding; Bristol-Myers Squibb: Research Funding; Mayo Clinic Rochester: Employment; LAM Therapeutics: Research Funding; LAM Therapeutics: Research Funding; Seattle Genetics: Research Funding; Mayo Clinic Rochester: Employment; Mayo Clinic Rochester: Employment; Trillium: Research Funding; LAM Therapeutics: Research Funding; Seattle Genetics: Research Funding; Seattle Genetics: Research Funding; Seattle Genetics: Research Funding; Trillium: Research Funding; Affimed: Research Funding; Bristol-Myers Squibb: Research Funding; Seattle Genetics: Research Funding; LAM Therapeutics: Research Funding; Bristol-Myers Squibb: Research Funding; LAM Therapeutics: Research Funding; Regeneron: Research Funding; Regeneron: Research Funding; Seattle Genetics: Research Funding; Regeneron: Research Funding; Trillium: Research Funding; Affimed: Research Funding; Regeneron: Research Funding; LAM Therapeutics: Research Funding; Affimed: Research Funding; Trillium: Research Funding; Affimed: Research Funding; Mayo Clinic Rochester: Employment; Regeneron: Research Funding; Bristol-Myers Squibb: Research Funding; Bristol-Myers Squibb: Research Funding; Mayo Clinic Rochester: Employment; Regeneron: Research Funding; LAM Therapeutics: Research Funding; Affimed: Research Funding; Regeneron: Research Funding; LAM Therapeutics: Research Funding; Seattle Genetics: Research Funding; Seattle Genetics: Research Funding; Bristol-Myers Squibb: Research Funding; Trillium: Research Funding; Mayo Clinic Rochester: Employment. Younes:Roche: Consultancy, Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Curis: Honoraria, Research Funding; Merck: Honoraria, Research Funding; Abbvie: Honoraria; Takeda: Honoraria; Pharmacyclics: Research Funding; AstraZeneca: Research Funding; Genentech: Research Funding; Biopath: Consultancy; Xynomics: Consultancy; Epizyme: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; HCM: Consultancy; BMS: Research Funding; Syndax: Research Funding. Gallamini:Takeda: Consultancy; Roche: Consultancy. Miao:Millennium Pharmaceuticals, Inc., Cambridge, MA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment, Equity Ownership. Liu:Takeda: Employment. Fenton:Seattle Genetics, Inc.: Employment, Equity Ownership. Forero-Torres:Seattle Genetics: Employment, Equity Ownership, Honoraria, Research Funding.

Introduction Approximately 20% of patients (pts) with classical Hodgkin lymphoma (cHL) are age ≥ 60 years (yrs) at diagnosis (dx). Standard anthracycline-based therapies (ABTx) have historically shown lower efficacy and greater toxicity in this older population compared with younger pts, especially for unfit or frail pts. However, prior analyses have pre-dated the use of brentuximab vedotin (BV) and other novel targeted agents in the front-line setting and there remains no clearly defined or unified standard of care for this pt population. Studies in older lymphoma pts have also defined specific categories of pt fitness that may potentially guide therapy, although continued validation of these definitions in cHL are needed. We performed a large, multicenter retrospective study to identify current practice patterns in the US in older untreated cHL pts with specific attention to pt fitness using established definitions and to outcomes with ABTx versus non-ABTx. Methods Following IRB approval at each site, detailed pathologic and clinical data, including geriatric assessments (GAs) for the latter, were collected across 10 US academic medical centers. Eligible pts included: cHL dx on or after 1/1/2010, age ≥ 60 yrs at dx, and no preceding hematologic malignancy. Subjects with inadequate clinicopathologic and outcomes data or with dx other than cHL were excluded. A multivariable Cox proportional hazards model was developed to study the association of PFS and OS with various factors of interest, and survival rates were estimated by Kaplan-Meier using SPSS. Associations were considered significant for two-sided P values ≤ 0.05. Results Among 254 eligible older cHL pts with newly diagnosed disease, clinical features included: median age 67 yrs (range 60-90+), 54% male, 64% stage III/IV, 46% B symptoms, and 86.1% ECOG PS 0-1. 68.9% had nodular sclerosis, 18.9% mixed cellularity, and 12.2% other subtypes; EBV was detectable by IHC or peripheral blood in 39.3% of evaluable cases (n=98). In terms of geriatric measures, 31 pts (12.2%) had loss of at least one ADL; 40 (15.8%) had a geriatric syndrome; and 16 (6.3%) had both. Of note, only one pt underwent a comprehensive GA prior to treatment. Using established fitness definitions in lymphoma (Tucci et al, 2015), pts were classified as "Fit" (n=129; 50.8%), "Unfit" (n=8; 3.2%), or "Frail" (n=112 (44.1%); 5 (2%) were unclassifiable due to incomplete data (Table 1). Front-line regimens included ABVD (n=145; 57.1%), AVD (n=33; 13.0%), and CHOP (n=18; 7.1%). 6 pts (2.4%) received BV monotherapy; 21 (8.3%) received BV with AVD, the latter either concurrently (N=11) or sequentially (n=10). 11 pts did not receive systemic tx, of whom 9 received radiation alone; 58 pts received radiation with systemic tx. ABVD recipients received an average of 7.4 doses of bleomycin (range 1-14) and 18.4% (n=26) had pulmonary toxicity. In addition, 56.7% (n=130) of pts experienced at least one tx-related toxicity, which was similar across all fitness groups (Table 1). 15.1% (n=38) of pts stopped tx due to toxicity, which was noted more often in "frail" pts though it was relatively uncommon. 11 pts (4.3%) experienced treatment-related mortality (TRM). Compared with pts receiving non-ABTx, ABTx was associated with significantly improved PFS (HR 0.391, P=0.008) and OS (HR 0.195, P=0.0004). ECOG PS >1 was associated with inferior PFS (HR=1.96, P=0.017) and OS (HR=3.09, P=0.002). Pts defined as "frail" had no apparent difference in PFS compared with fit pts (Figure 1A;P=0.169), although decreased OS was seen (Figure 1B; P=0.01). Discussion To the best of our knowledge, these data represent one of the largest analyses of older cHL pts in the modern era. Our real-world analysis shows that in those who are able to receive them, anthracyclines provide meaningful survival benefit in this older cHL patient population and can be well-tolerated for many pts. The impact of dose intensity and backbone regimen are not yet known. In addition, current definitions of "fitness" incompletely identified pts at risk for poor outcomes or greater toxicity. Further studies are planned to better delineate fitness in this population. Disclosures Bartlett: Celgene: Research Funding; ADC Therapeutics: Consultancy, Research Funding; Affimed: Research Funding; Merck: Research Funding; Janssen: Research Funding; Immune Design: Research Funding; Gilead: Research Funding; Millenium: Research Funding; Pfizer: Research Funding; Pharmacyclics: Research Funding; Seattle Genetics: Research Funding; Forty Seven: Research Funding; Genenetech: Research Funding; Bristol-Myers Squibb: Research Funding. Grover:Seattle Genetics: Consultancy. Bennani:Adicet Bio: Other: Advisory board; Bristol-Myers Squibb: Research Funding; Adicet Bio: Other: Advisory board; Seattle Genetics: Other: Advisory board; Seattle Genetics: Other: Advisory board; Purdue Pharma: Other: Advisory board; Seattle Genetics: Other: Advisory board; Purdue Pharma: Other: Advisory board; Kite Pharma: Other: Advisory board; Bristol-Myers Squibb: Research Funding; Bristol-Myers Squibb: Research Funding; Kite Pharma: Other: Advisory board; Kite Pharma: Other: Advisory board; Purdue Pharma: Other: Advisory board; Adicet Bio: Other: Advisory board. Hill:Kite: Consultancy, Honoraria; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AstraZeneca: Consultancy, Honoraria; Celegene: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria; Takeda: Research Funding; Amgen: Research Funding; TG therapeutics: Research Funding; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Consultancy, Research Funding. Advani:Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead Sciences, Inc./Kite Pharma, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees; Millennium: Research Funding; Kura: Research Funding; Janssen: Research Funding; Autolus: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bayer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Merck: Research Funding; Regeneron: Research Funding; Infinity Pharma: Research Funding; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Research Funding; Celmed: Consultancy, Membership on an entity's Board of Directors or advisory committees; Forty-Seven: Research Funding; Roche/Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Kyowa Kirin Pharmaceutical Developments, Inc.: Consultancy; Agensys: Research Funding; Stanford University: Employment, Equity Ownership; Seattle Genetics: Consultancy, Research Funding; Cell Medica, Ltd: Consultancy; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Svoboda:AstraZeneca: Consultancy; Celgene: Research Funding; Incyte: Research Funding; Pharmacyclics: Consultancy, Research Funding; Kyowa: Consultancy; Merck: Research Funding; BMS: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding. Magarelli:Tevan Oncology: Speakers Bureau. Feldman:Takeda: Honoraria, Speakers Bureau; Celgene: Honoraria, Research Funding, Speakers Bureau; Seattle Genetics: Consultancy, Honoraria, Other: Travel expenses, Speakers Bureau; AbbVie: Honoraria, Other: Travel expenses, Speakers Bureau; Pharmacyclics: Honoraria, Other: Travel expenses, Speakers Bureau; Janssen: Honoraria, Speakers Bureau; Kite Pharma: Honoraria, Other: Travel expenses, Speakers Bureau; Bayer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; Cell Medica: Research Funding; Roche: Research Funding; Corvus: Research Funding; Eisai: Research Funding; Kyowa Hakko Kirin: Research Funding; Pfizer: Research Funding; Portola Pharma: Research Funding; Roche: Research Funding; Trillium: Research Funding; Viracta: Research Funding. Cohen:Astra Zeneca: Research Funding; ASH: Research Funding; UNUM: Research Funding; Hutchison: Research Funding; Takeda Pharmaceuticals North America, Inc.: Research Funding; Gilead/Kite: Consultancy; Lymphoma Research Foundation: Research Funding; LAM Therapeutics: Research Funding; Seattle Genetics, Inc.: Consultancy, Research Funding; Bristol-Meyers Squibb Company: Research Funding; Janssen Pharmaceuticals: Consultancy; Genentech, Inc.: Consultancy, Research Funding. Evens:Seattle Genetics: Consultancy, Honoraria, Research Funding; Tesaro: Research Funding; Epizyme: Consultancy, Honoraria; Verastem: Consultancy, Honoraria; Pharmacyclics: Consultancy, Honoraria. Portell:AbbVie: Research Funding; Pharmacyclics: Consultancy; Janssen: Consultancy; Genentech: Consultancy, Research Funding; Amgen: Consultancy; Bayer: Consultancy; BeiGene: Consultancy, Research Funding; Kite: Consultancy, Research Funding; Acerta/AstraZeneca: Research Funding; TG Therapeutics: Research Funding; Xencor: Research Funding; Roche/Genentech: Research Funding; Infinity: Research Funding.

Abstract Introduction: The most effective initial therapy for older adults with CLL has not yet been established due to the lack of comparison of chemoimmunotherapy (CIT) and targeted therapy with the Bruton's Tyrosine Kinase (BTK) inhibitor ibrutinib. CIT has been the gold standard since studies showing that addition of CD20 antibody to chemotherapy prolongs survival. Bendamustine plus rituximab (BR) is one standard, more aggressive CIT regimen for patients (pts) age 65 or older. While ibrutinib has been FDA approved for untreated CLL since 2016, it has only been compared to chlorambucil, which is relatively ineffective, and never before to aggressive CIT. Additionally, the benefit of the addition of rituximab to ibrutinib in this setting has not been prospectively studied in a phase 3 trial. As part of a randomized phase 3 trial, the Alliance sought to answer these important clinical questions. Pts and Methods: Alliance A041202 is a multicenter NCI National Clinical Trials Network phase 3 study comparing BR (Arm 1) with ibrutinib (Arm 2) and the combination of ibrutinib plus rituximab (Arm 3) to determine whether ibrutinib-containing regimens are superior to CIT in terms of PFS. Additionally, this study sought to determine if adding rituximab to ibrutinib would prolong PFS over ibrutinib alone. At time of progression, pts on Arm 1 could cross over to Arm 2. Eligible pts were those age ≥ 65 years with previously untreated, symptomatic CLL. Pts had a CrCl ≥ 40 mL/min, bilirubin ≤ 1.5 x ULN, and no significant life-limiting intercurrent illness or need for warfarin treatment. Pts were stratified based upon Rai stage, Zap-70 methylation performed centrally, and del(17)(p13.1) or del(11)(q22.3) by local interphase cytogenetics and were randomized 1:1:1 to each arm. With 166 pts per arm, the trial was powered to detect an improvement in 2-year PFS from 61% in Arm 1 to 75% in Arms 2 or 3 (HR=0.586) using two one-sided log-rank tests with type I error rate of 2.5% and 90% power. The Alliance Data and Safety Monitoring Board approved the data release after meeting the protocol-defined efficacy threshold at a planned interim analysis with a one-sided critical value of 0.001538. These data were locked July 2, 2018; updated results will be presented at the meeting. Results: Between 12/9/2013 and 5/16/2016, 547 pts were registered and randomized (Arms 1: 183, 2: 182, and 3: 182). Median age was 71 years and 67% of pts were men. High-risk Rai stage (stage III/IV) was seen in 54%, unmethylated Zap-70 in 53%, and del(17p) or del(11q) by local FISH in 28%. Local vs centralized FISH was performed for del(11q) and del(17p) with agreement between local and central results in 94% (Kappa=0.80) and 97% (Kappa=0.76) of pts, respectively. 525 (96%) pts were eligible and included in the primary PFS analysis (Arms 1: 176, 2: 178, and 3: 171). With median follow-up of 32 months (mo), median PFS was 41 mo in Arm 1 and has not been reached in Arms 2 or 3 (HR comparing Arm 2 to 1 is 0.40 with one-sided p<0.0001; HR comparing Arm 3 to 1 is 0.41 with one-sided p<0.0001; HR comparing Arm 3 to 2 is 1.01 with one-sided p=0.48). 2-year PFS estimates were 74%, 87% in 2, and 88% in Arms 1, 2, and 3 respectively. At this time, there are no significant differences in overall survival (OS) among arms (p=0.87), median OS has not been reached for any arm, and 2-year OS estimates were 95%, 90%, and 94% in Arms 1, 2, and 3, respectively. Adverse events (AEs) were compared among arms using Fisher's exact tests. Grade 3+ treatment-emergent AEs were seen in 428 of 537 evaluable pts with 61%, 41%, and 38% of pts experiencing Grade 3+ heme AEs (p<0.0001) and 60%, 72%, and 71% of pts experiencing Grade 3+ non-heme AEs (p=0.03) in Arms 1, 2, and 3 respectively. Grade 5 AEs were seen in 5 (2.8%), 14 (7.8%), and 14 (7.7%) pts (p=0.07). Unexplained or unwitnessed death over the entire observation period was seen in 2 (1.1%), 7 (3.9%), and 4 (2.2%) pts (p=0.24) in Arms 1, 2, and 3 respectively. Conclusions: This international phase 3 trial demonstrates that ibrutinib produces superior PFS to standard CIT in older pts with CLL and justifies it as a standard of care treatment for pts age 65 and older. The addition of rituximab does not prolong PFS with ibrutinib. While ibrutinib represents a major therapeutic advance, toxicities and also cost justify future efforts to reduce the need for long-term continuous treatment. Support: K23CA178183, R01CA183444, U10CA180821, U10CA180882, U24CA196171, Clinicaltrials.gov identifier: NCT01886872 Figure. Figure. Disclosures Ding: Merck: Research Funding. Bartlett:Astra Zeneca: Research Funding; ImaginAB: Research Funding; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Research Funding; Bristol-Meyers Squibb: Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Research Funding; Pharmacyclics: Research Funding; Affimed: Research Funding; Janssen: Research Funding; Novartis: Research Funding; Merck & Co: Research Funding; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Acerta: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; Immune Design: Research Funding; Forty Seven: Research Funding; Novartis: Research Funding; Millennium: Research Funding. Brander:BeiGene: Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; TG Therapeutics: Consultancy, Honoraria, Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; Genentech: Consultancy, Honoraria, Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; Novartis: Consultancy, Other: DSMB; AbbVie: Consultancy, Honoraria, Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; Pharmacyclics, an AbbVie Company: Consultancy, Honoraria, Research Funding; Teva: Consultancy, Honoraria; Acerta: Other: Institutional research funding for non investigator initiated clinical trial, Research Funding; DTRM: Other: Institutional research funding for non investigator initiated clinical trial, Research Funding. Barr:AbbVie, Gilead: Consultancy. Parikh:Gilead: Honoraria; Pharmacyclics: Honoraria, Research Funding; MorphoSys: Research Funding; Janssen: Research Funding; AstraZeneca: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding. Coutre:Celgene: Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Pharmacyclics LLC, an AbbVie Company: Honoraria, Research Funding; Gilead: Research Funding; Beigene: Consultancy; AbbVie: Consultancy, Research Funding. Lozanski:Novartis: Research Funding; BI: Research Funding; Genentech: Research Funding; Stem Line: Research Funding; Coulter: Research Funding; Beckman: Research Funding. Larson:Ariad/Takeda: Consultancy, Research Funding; BristolMyers Squibb: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Novartis: Consultancy, Research Funding. Erba:Amgen: Research Funding; Juno: Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Daiichi Sankyo: Consultancy, Research Funding; MacroGenics: Consultancy; Juno: Research Funding; Janssen: Research Funding; Seattle Genetics: Consultancy, Research Funding; Janssen: Research Funding; Juno: Research Funding; Agios: Consultancy, Speakers Bureau; MacroGenics: Consultancy; Incyte: Consultancy, Speakers Bureau; Seattle Genetics: Consultancy, Research Funding; Takeda/Millenium: Research Funding; Novartis: Consultancy, Speakers Bureau; Takeda/Millenium: Research Funding; Incyte: Consultancy, Speakers Bureau; MacroGenics: Consultancy; Celgene: Consultancy, Speakers Bureau; Janssen: Research Funding; Novartis: Consultancy, Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Astellas: Research Funding; Glycomimetics: Consultancy, Other: Chair, Data and Safety Monitoring Committee; MacroGenics: Consultancy; Daiichi Sankyo: Consultancy, Research Funding; Pfizer: Consultancy, Other: grant; Astellas: Research Funding; Juno: Research Funding; Janssen: Research Funding; Novartis: Consultancy, Speakers Bureau; Amgen: Research Funding; Agios: Consultancy, Speakers Bureau; Astellas: Research Funding; Agios: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Amgen: Research Funding; Pfizer: Consultancy, Other: grant; Pfizer: Consultancy, Other: grant; Astellas: Research Funding; Amgen: Research Funding; Agios: Consultancy, Speakers Bureau; Incyte: Consultancy, Speakers Bureau; Incyte: Consultancy, Speakers Bureau; Jazz: Consultancy, Speakers Bureau; Immunogen: Consultancy, Research Funding; Jazz: Consultancy, Speakers Bureau; Immunogen: Consultancy, Research Funding; Glycomimetics: Consultancy, Other: Chair, Data and Safety Monitoring Committee; Pfizer: Consultancy, Other: grant; Jazz: Consultancy, Speakers Bureau; Immunogen: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Jazz: Consultancy, Speakers Bureau; Seattle Genetics: Consultancy, Research Funding; Celgene: Consultancy, Speakers Bureau; Immunogen: Consultancy, Research Funding; Takeda/Millenium: Research Funding; Glycomimetics: Consultancy, Other: Chair, Data and Safety Monitoring Committee; Celgene: Consultancy, Speakers Bureau; Takeda/Millenium: Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Glycomimetics: Consultancy, Other: Chair, Data and Safety Monitoring Committee. Owen:Janssen: Honoraria, Research Funding; Celgene: Research Funding; AstraZeneca: Honoraria, Research Funding; Pharmacyclics: Research Funding; F. Hoffmann-La Roche Ltd: Honoraria, Research Funding; AbbVie: Research Funding; Merck: Honoraria; Teva: Honoraria. Abramson:Bayer: Consultancy; Novartis: Consultancy; Merck: Consultancy; Karyopharm: Consultancy; Seattle Genetics: Consultancy; Verastem: Consultancy; Humanigen: Consultancy; Juno Therapeutics: Consultancy; Gilead: Consultancy; Celgene: Consultancy; Amgen: Consultancy.

Abstract Introduction For patients with Stage III/IV Hodgkin lymphoma (HL), lack of response as assessed by PET scan following cycle 2 (PET2) of doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) is predictive of poor clinical outcomes. SWOG Study S0816 utilized response-adapted therapy, where patients achieving a complete remission (CR) on PET2 (Deauville Score ≤ 3) continued 4 additional cycles of ABVD and those patients unable to achieve a complete remission (CR) on PET2 (Deauville Score > 3) were switched to therapy with escalated bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone (eBEACOPP) for 6 cycles. This study demonstrated a 2-year PFS of 64% in the PET2+ patients after switching to eBEACOPP, which was much higher than expected (Press 2016). Herein, we report the 5-year follow-up of survival and toxicities of the patients treated on S0816. Methods Patients with Stage III/IV HL were enrolled to S0816 from 7/1/09-12/2/12 (n=358). Eligible patients were age 18-60 years, had measurable disease, no prior lymphoma therapy, a Zubrod performance status of 0-2, and no serious medical comorbidities. Patients were treated with response-adapted therapy as above. A subset of 336 eligible and HIV-negative patients were analyzed. Of 336, 331 had central review of PET2. PFS and OS estimates were calculated using the Kaplan-Meier method. The two-sided Fisher's exact test was used to compare the rate of second cancer between patients switched to treatment eBEACOPP and those treated with continued ABVD after 2 initial cycles of ABVD. Results The median age of patients was 32 years (range, 18-60). All were Stage III/IV and 51% had an International Prognostic Score of ≥ 3. PET2 was negative in 271 patients (82%) and positive in 60 patients (18%). Of PET2+ patients, 49 (82%) switched to eBEACOPP as planned and 11 (18%) declined. Median follow-up is now 5.9 years (range, 0.2-8.3 years). Eighty-five (25%) patients have either progressed or died, for an estimated 5-year PFS of 74% (95% CI: 69%-79%; Figure 1). There were 64 (24%) events in those patients who were PET2- for a 5-year PFS of 76% (95% CI: 71-81%; Figure 2). There were 20 (33%) events in those patients who were PET2+ for a 5-year PFS of 65% (95% CI: 51-76%; Figure 2). One event occurred in a patient without central review of PET2. Nineteen patients have died for an estimated 5-year overall survival of 94% (95% CI: 91%-96%; Figure 1). Eleven (3%) patients died of HL including 6 (2%) that had PET2- and 5 (8%) that had PET2+. Other causes of death included: treatment-related toxicity [sepsis (eBEACOPP n=1), bleomycin lung injury (eBEACOPP n=1; ABVD n=1), and graft versus host disease (ABVD n=1)]; second primary cancers [(eBEACOPP n=2; cervical cancer and non-Hodgkin lymphoma (NHL)]; and unknown causes (ABVD n=2). Post-therapy grade 3 adverse events were uncommon but included 1 case each of heart failure, peripheral neuropathy, prolonged neutropenia, diarrhea, DVT (catheter-related) in patients who received continued ABVD and osteonecrosis of hips/shoulders in patients who received eBEACOPP. There were 13 (4%) cases of reported second cancers, including 7 (14%) in patients treated with eBEACOPP [1 each of myelodysplastic syndrome, kidney, melanoma, NHL, cervical, medullary thyroid, and basal cell carcinoma] and 6 (2%) in patients treated with ABVD (1 each of kidney, melanoma, NHL, bladder, prostate, and squamous cell carcinoma; 2-sided Fisher's exact P value = 0.001). Conclusions The long-term overall survival of the patients treated on S0816 remains high (94%) at 5 years. Despite historical data suggesting favorable clinical outcomes in patients with a negative PET2, nearly 25% of these patients experienced relapse events, demonstrating limitations of a PET-adapted approach and of standard frontline therapy with ABVD. In patients who were PET2+, PFS was favorable relative to historical series, but was associated with a high rate of secondary malignancies. Our results emphasize the importance of long-term follow-up in this disease, and the need for better biomarkers at diagnosis of HL and less toxic approaches for patients with a positive PET2. Acknowledgment In memory of Oliver W. Press, principal investigator of this trial, who died in 2017. Disclosures Straus: DAVA Oncology: Consultancy, Honoraria; Medical Crossfire: Speakers Bureau; Millenium (Takeda): Consultancy, Research Funding; JUNO: Consultancy; Bayer: Consultancy; Onco Tracker: Consultancy; Seattle Genetics: Consultancy; Roch China: Speakers Bureau; InPractice Elselvier: Consultancy; Memorial Sloan Kettering Cancer Center: Employment. Rimsza:NanoString: Other: Inventor on the patent for the Lymph2Cx assay. Bartlett:ImaginAB: Research Funding; Genentech: Research Funding; Forty Seven: Research Funding; Bristol-Meyers Squibb: Research Funding; Merck & Co: Research Funding; Novartis: Research Funding; Celgene: Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Research Funding; Immune Design: Research Funding; Acerta: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astra Zeneca: Research Funding; Millennium: Research Funding; Janssen: Research Funding; Affimed: Research Funding; Novartis: Research Funding; Pharmacyclics: Research Funding. Evens:Janssen: Consultancy; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bayer: Consultancy; Seattle Genetics, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics International DMC: Membership on an entity's Board of Directors or advisory committees; Affimed: Consultancy; Abbvie: Consultancy; Novartis: Consultancy; Tesaro: Research Funding; Acerta: Consultancy. LaCasce:Seattle Genetics: Consultancy, Honoraria; Bristol-Myers Squibb: Other: Data safety and monitoring board; Research to Practice: Speakers Bureau; Humanigen: Consultancy, Honoraria. Barr:AbbVie, Gilead: Consultancy. Leonard:Gilead: Consultancy; Sutro: Consultancy; BMS: Consultancy; Juno: Consultancy; MEI Pharma: Consultancy; Celgene: Consultancy; Bayer: Consultancy; Pfizer: Consultancy; AstraZeneca: Consultancy; Biotest: Consultancy; Novartis: Consultancy; Karyopharm: Consultancy; Genentech/Roche: Consultancy; ADC Therapeutics: Consultancy; United Therapeutics: Consultancy. Kahl:Genentech: Consultancy; Celgene: Consultancy; Acerta: Consultancy; AstraZeneca: Consultancy; Juno: Consultancy; CTI: Consultancy; ADC Therapeutics: Consultancy; Abbvie: Consultancy; Gilead: Consultancy; Seattle Genetics: Consultancy. Smith:BMS: Consultancy; Portola: Honoraria. Friedberg:Bayer: Honoraria.

Abstract Background AFM13 is a bispecific, tetravalent NK cell-engaging antibody construct binding to CD30 on CD30+ tumor cells and CD16A on NK cells. By engaging CD16A-positive NK cells, AFM13 leads to NK cell-mediated killing of CD30-positive lymphoma cells (Reusch et al., 2014) making it an attractive agent to target classical Hodgkin lymphoma (HL). Pembrolizumab is a PD-1 blocking antibody which has shown high single-agent response rates in patients (pts) with relapsed/refractory HL (RRHL; Armand et al., 2016, Chen et al., 2017). AFM13 has shown clinical activity in RRHL as a single agent in a preceding Phase 1 study (Rothe et al., 2015). Preclinical in vivo data of the combination of AFM13 with PD-1 blockade showed synergistic activity and the potential for induction of cross-talk between innate and adaptive immunity (Zhao et al., 2016). We hypothesize that the combination of the two agents could improve outcomes in pts with RRHL. Methods This Phase 1b study is evaluating the safety and tolerability of the combination of AFM13 with pembrolizumab (Keytruda) as salvage therapy after failure of standard therapies including brentuximab vedotin (BV) in HL (NCT02665650). Pts receive escalating doses of AFM13 in combination with pembrolizumab at a dose of 200 mg flat administered every 3 weeks following a classical 3+3 design, followed by enrollment into an extension cohort at the maximum tolerated dose (MTD)/maximum administered dose (MAD). Response assessment is performed every 12 weeks by PET/CT according to the Lugano Classification (Cheson et al., 2014). The main objectives of the study is to ascertain the MTD/MAD along with the preliminary efficacy of the combination. Results As of June 29, 2018, 30 pts have been enrolled into the study. The median age is 34 years (range, 18-73), with a median of 4 (range 3-7) prior lines of therapy. All pts had relapsed or refractory disease (43% relapsed, 57% refractory) and had failed standard treatments including BV and 43% of pts (13/30) had BV as their latest therapy. Thirty seven percent (11/30) had undergone prior autologous stem cell transplantation. All 30 pts have completed the 6-week dose-limiting toxicity (DLT) observation period. Twelve pts were enrolled into the dose escalation cohorts (Cohorts 1 (n=3), 2 (n=3), and 3 (n=6)) and 18 into the Extension Cohort, with a total of 24 patients treated at the MAD (dose level 3). One DLT was observed in Cohort 3 (missing ≥25% of AFM13 during the DLT period) and another observed in the Extension Cohort (G4 infusion-related reaction; IRR). The most common related adverse events (AEs) were IRRs (80%), rash (30%), pyrexia (23%), nausea (23%), diarrhea (20%), fatigue (17%), headache (17%), increased aspartate aminotransferase (13%), and increased alanine aminotransferase (10%). Treatment related G3/4 AEs included IRRs (13%), elevated AST (3%), gastritis (3%), hypotension (3%), nausea (3%), neutropenia (3%), and vomiting (3%). The majority of IRRs were manageable with standard of care measures and did not lead to treatment discontinuations. Included in the efficacy analysis were the best response from 29 evaluable pts who had at least one post-baseline disease assessment as of the data cutoff on June 29, 2018. The overall response rate (ORR) and complete response (CR) rate for evaluable pts treated at the dose and schedule chosen for expansion (n=23; Cohort 3 and Extension Cohort) were 87% and 35% by the investigator-confirmed assessment, respectively. Independent assessment resulted in an ORR of 87% and CR rate of 39% for these pts. Updated data for all 30 patients will be presented at the meeting. Conclusions The combination of AFM13 and pembrolizumab is a well-tolerated salvage therapy in pts with RRHL. IRRs were the most frequently observed adverse events; however, most of these events were of mild or moderate severity and manageable. Both the ORR and CR rate compare favorably to monotherapy pembrolizumab in a similar RRHL population (Chen et al., 2017). The combination of AFM13 and pembrolizumab could be a potential new therapeutic option for HL patients. Disclosures Bartlett: Immune Design: Research Funding; Affimed: Research Funding; Bristol-Meyers Squibb: Research Funding; Merck & Co: Research Funding; Pharmacyclics: Research Funding; Celgene: Research Funding; Pharmacyclics: Research Funding; Genentech: Research Funding; Forty Seven: Research Funding; Novartis: Research Funding; Novartis: Research Funding; Millennium: Research Funding; ImaginAB: Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Research Funding; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astra Zeneca: Research Funding; Acerta: Membership on an entity's Board of Directors or advisory committees. Chen:Affimed: Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Genentech Inc.: Consultancy; Seattle Genetics: Consultancy, Honoraria, Research Funding, Speakers Bureau; Merck & Co., Inc.: Consultancy, Research Funding, Speakers Bureau; Millennium Pharmaceuticals: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding. Domingo-Domenech:Affimed: Research Funding. Forero-Torres:Affimed: Research Funding. Garcia-Sanz:Affimed: Research Funding. Devata:Affimed: Research Funding. Rodriguez Izquierdo:Affimed: Research Funding. Lossos:Affimed: Research Funding. Reeder:Affimed: Research Funding. Sher:Affimed: Research Funding. Choe-Juliak:Affimed: Employment. Prier:Affimed: Research Funding. Schwarz:Affimed: Employment. Strassz:Affimed: Employment. Alland:Affimed: Employment. Ansell:Bristol-Myers Squibb: Research Funding; Celldex: Research Funding; LAM Therapeutics: Research Funding; Trillium: Research Funding; Pfizer: Research Funding; Regeneron: Research Funding; Seattle Genetics: Research Funding; Merck & Co: Research Funding; Affimed: Research Funding; Takeda: Research Funding.

Abstract Introduction: Aggressive chemo-immunotherapy followed by peripheral blood stem cell autografting (ASCT) in CALGB (Alliance) 59909 achieved a median progression-free survival (PFS) in MCL of 5 years (Damon et al JCO, 2009), but late recurrences occurred. Using the CALGB 59909 treatment backbone, we evaluated tolerability and efficacy of adding post-transplant bortezomib consolidation (BC) or maintenance (BM)in a randomized phase II trial. Interim results of CALGB (Alliance) 50403 were previously presented (ASH 2015) demonstrating 5 yr PFS 70% and 69% for the BM and BC arms respectively. We now report final 8 year follow up results from this trial and compare outcomes to CALGB 59909, which differed from CALGB 50403 only by the absence of post-transplant bortezomib. Methods: The primary endpoint was PFS measured from randomization for each treatment arm. Induction therapy was with 2-3 cycles of augmented R-CHOP (2000 mg/m2 cyclophosphamide) and methotrexate (300 mg/m2) followed by high-dose cytarabine/etoposide/rituximab(R)/filgrastim (EAR) stem cell mobilization and cyclophosphamide/carmustine/etoposide (CBV) ASCT. After 2 doses of post-transplant R, patients were randomized to BC (1.3 mg/ m2 IV days 1, 4, 8, 11 of a 3-week cycle for 4 cycles) or BM (1.6 mg/m2 IV weekly x4 every 8 weeks for 18 months) beginning at approximately day 90. Minimal residual disease (MRD) was analyzed using patient-specific PCR probes for the bcl-1 / IgH junction or the IgH CDR3 region. Results: 151 patients were enrolled from 10/2006 - 6/2010 at 14 sites; 147 who received treatment are included in this analysis. Median age was 59 years (29-69); stage II (2.7%), III (11.6%), IV (85.0%); MIPI low (52.4%), intermediate (30.6%), high (17.0%); blastoid histology (12.9%); bone marrow involvement (81.0%); Ki67 was evaluated in 86 and was >30% in 17.4% of patients. 118 (80%) underwent ASCT and 102 (68%) were randomized. Most withdrawals (45) were for progression (10) or adverse events (AEs) (19) including 4 treatment-related deaths. Fifty-two patients were randomized to BM and 50 to BC. Following randomization, 34 (65%) completed BM and 33 (66%) completed BC. Withdrawal for AEs occurred in 14 (28%) of BC and 7 (13%) of BM patients (p = 0.09), most for cytopenias or peripheral neuropathy. With a median follow-up 7.8 years from randomization (8.3 from registration), the median PFS from randomization for the BM arm was not reached and was 8.9 years (95% CI 7.2 to not reached) for the BC arm. Both arms had median PFS significantly greater than the null hypothesis setting median PFS to 4 years (p < 0.001; 1-sided test of exponential parameter)The 8-year PFS estimates in the BM and BC arms were 77% (95% CI 66-90%) and 58% (95% CI 44-76%), respectively. Among all 147 patients treated on CALGB 50403, 8-year PFS from time of registration was 43.6% (35.6-53.3%). PFS from registration was not significantly extended in CALGB 50403 compared with CALGB 59909 (log rank p=0.24), but using a landmark analysis from time of transplant, PFS was significantly extended in CALGB 50403 (log rank p=0.005)(fig 1). Baseline patient characteristics in the two studies were not significantly different. In CALGB 50403, 8-year PFS from registration by MIPI was 52.0% (95% CI 41.1-66.0%) in MIPI low risk, 37.5% (95% CI 25.3-55.4%) in intermediate risk, and 28.2% (95% CI 13.7-57.9%) in high-risk. Bone marrow MRD results were collected for 42 patients post-induction therapy; 8-year PFS estimates were 80.2% (95% CI 62.2-100%) (n=17) and 43.2% (95% CI 27.3-68.2%) (n=25) for MRD-negative and MRD-positive patients, respectively (p=0.009). Conclusions: Induction chemotherapy followed by ASCT and either BC or BM was efficacious and tolerable, although BC was associated with more withdrawals for toxicity. PFS was not significantly different between BC and BM. The comparison between studies 50403 and 59909 with long-term follow up continues to suggest a PFS benefit from the addition of BC or BM among patients undergoing transplant. This did not translate into a PFS benefit from time of study enrollment possibly due to the higher pre-transplant dropout rate in 50403. MRD-negativity following induction chemo-immunotherapy is highly associated with improved PFS and the role of ASCT in post-induction MRD-negative patients is currently under investigation in a randomized clinical trial. Support: U10CA180821, U10CA180882, U24CA196171; ClinicalTrials.gov Identifier: NCT00310037 Disclosures Kaplan: Bayer Pharmaceuticals: Consultancy. Maurer:Celgene: Research Funding; Morphosys: Research Funding; Nanostring: Research Funding. Stock:Jazz Pharmaceuticals: Consultancy. Bartlett:Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Blum:Acerta: Consultancy; Astra-Zeneca: Consultancy. LaCasce:Seattle Genetics: Consultancy, Honoraria; Humanigen: Consultancy, Honoraria; Research to Practice: Speakers Bureau; Bristol-Myers Squibb: Other: Data safety and monitoring board. Leonard:AstraZeneca: Consultancy; Juno: Consultancy; BMS: Consultancy; ADC Therapeutics: Consultancy; Gilead: Consultancy; Biotest: Consultancy; Karyopharm: Consultancy; Novartis: Consultancy; MEI Pharma: Consultancy; Celgene: Consultancy; United Therapeutics: Consultancy; Sutro: Consultancy; Genentech/Roche: Consultancy; Pfizer: Consultancy; Bayer: Consultancy. Cheson:AbbVie, Roche/Genentech, Pharmacyclics, Acerta, TG Therapeutics: Consultancy.

Abstract Background: The phase 3 ECHELON-1 study assessed frontline brentuximab vedotin administered with doxorubicin, vinblastine, and dacarbazine (A+AVD) vs doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) in patients (pts) with advanced cHL (NCT01712490). The primary endpoint of ECHELON-1, modified PFS (mPFS) per independent review facility (IRF), is defined as (1) progressive disease, (2) death, or (3) subsequent anticancer therapy (chemotherapy [chemo] and/or radiotherapy [RT]) following detection of a non-complete response (non-CR = Deauville score 3-5) at end of frontline therapy. A+AVD was superior to ABVD (hazard ratio [HR]=0.77; p=0.035) with 2-year mPFS rates of 82.1% and 77.2%; as previously reported. In pts with newly diagnosed cHL, the aim of frontline therapy is curative. Pts who do not achieve a satisfactory response to frontline therapy may initiate subsequent anticancer therapy prior to response criteria-defined progression. The measurement of traditional PFS becomes confounded, as pts may effectively be rescued from criteria-defined progression by subsequent treatment, resulting in an overestimation of PFS with frontline therapy (Connors et al. Haematologica 2016;101[s5]:22-3[P007]). To further evaluate modified and traditional PFS in the ECHELON-1 study, two sensitivity analyses were conducted. Methods: 1334 pts with Stage III (36%) or IV (64%) cHL were randomized 1:1 to receive A+AVD (n=664) or ABVD (n=670) on days 1 and 15, for up to six 28-day cycles. In addition to mPFS per IRF, mPFS per investigator (INV) was collected. A sensitivity analysis (mPFS-chemo) was performed in which RT following a non-CR at the completion of frontline therapy was not counted as an event: in this case, mPFS-chemo was defined as (1) progression, (2) death, or (3) receipt of additional anticancer chemo excluding RT for pts who are not in CR after completion of frontline therapy. A second sensitivity analysis of traditional PFS (PFS-traditional), defined as (1) progression or (2) death, was also performed. All analyses were performed per INV as, per protocol, IRF follow up of pts was not conducted after the initiation of subsequent therapy. Results: At 2 years, the rates of mPFS per INV (95% CI) for A+AVD vs ABVD were 81.0% (77.6-83.9%) vs 74.4% (70.7-77.7%), respectively; HR=0.72 (95% CI: 0.573, 0.914; p=0.006). Concordance between IRF and INV mPFS assessments was high among all pts in both arms, at 91%. A total of 123 mPFS events per INV were observed among pts treated with A+AVD, including 73 pts with PD, 15 deaths, and 35 who received additional anticancer therapy following evidence of non-CR at the end of frontline therapy, vs 164 per INV mPFS events among pts treated with ABVD, of which 103 were PD, 22 were deaths, and 39 were additional anticancer therapy following evidence of non-CR at the end of frontline therapy. Of the 35 (A+AVD) and 39 (ABVD) additional anticancer therapy events, chemo/RT following evidence of non-CR at the end of frontline therapy accounted for 11/24 and 17/22 of these events, respectively. For mPFS-chemo, a larger benefit in favor of A+AVD vs ABVD, with a HR=0.687 (95% CI: 0.534, 0.885; p=0.003), was observed. The 2-year mPFS-chemo (95% CI) was estimated as 84.0% (80.9-86.7%) for pts treated with A+AVD vs 77.3% (73.7-80.4%) for pts treated with ABVD. A total of 103 events were observed among pts in the A+AVD arm, including 78 pts with PD, 15 deaths, and 10 who received additional chemo following evidence of a non-CR at the end of frontline therapy, vs 145 events among pts treated with ABVD, of which 106 were PD, 22 were deaths, and 17 were additional chemo following evidence of non-CR at the end of frontline therapy. For PFS-traditional, an advantage in favor of A+AVD vs ABVD was also observed: HR=0.70 (95% CI: 0.54-0.91; p=0.006). The 2-year PFS estimate (95% CI) was 84.2% (81.1-86.9%) for A+AVD vs 78.0% (74.4-81.1%) for ABVD. In total, there were 101 PFS events in the A+AVD arm, including 86 pts with PD and 15 deaths; vs 140 PFS events in the ABVD arm, including 118 pts with PD and 22 deaths. Conclusions: Consistent with the primary outcome of ECHELON-1, a benefit in favor of A+AVD vs ABVD was observed independent of the inclusion of additional anticancer RT or chemo as survival events, in addition to progression or death. A traditional PFS assessment including only progression or death events demonstrated that A+AVD resulted in a 30% reduction in the risk of progression or death compared to ABVD. Figure. Figure. Disclosures Connors: Lilly: Research Funding; Bayer Healthcare: Research Funding; Janssen: Research Funding; Bristol Myers-Squibb: Research Funding; Merck: Research Funding; NanoString Technologies: Patents & Royalties: Named Inventor on a patent licensed to NanoString Technologies, Research Funding; Seattle Genetics: Honoraria, Research Funding; Roche Canada: Research Funding; Amgen: Research Funding; Genentech: Research Funding; F Hoffmann-La Roche: Research Funding; Cephalon: Research Funding; Takeda: Research Funding. Younes:J&J: Research Funding; Celgene: Honoraria; BMS: Honoraria, Research Funding; Sanofi: Honoraria; Abbvie: Honoraria; Curis: Research Funding; Genentech: Research Funding; Merck: Honoraria; Bayer: Honoraria; Pharmacyclics: Research Funding; Janssen: Honoraria, Research Funding; Novartis: Research Funding; Incyte: Honoraria; Seattle Genetics: Honoraria; Roche: Honoraria, Research Funding; Astra Zeneca: Research Funding; Takeda: Honoraria. Gallamini:Takeda: Consultancy, Speakers Bureau. Ansell:Pfizer: Research Funding; Trillium: Research Funding; Bristol-Myers Squibb: Research Funding; Affimed: Research Funding; Regeneron: Research Funding; LAM Therapeutics: Research Funding; Takeda: Research Funding; Merck & Co: Research Funding; Celldex: Research Funding; Seattle Genetics: Research Funding. Kim:J&J: Research Funding; Kyowa-Kirin: Research Funding; Mundipharma: Research Funding; Celltrion: Honoraria, Research Funding; Novartis: Research Funding; Takeda: Research Funding; Roche: Honoraria, Research Funding; Eisai: Honoraria, Research Funding; Celgene: Research Funding; Merck: Research Funding. Advani:Janssen: Research Funding; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Cell Medica: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board; Roche/Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board, Research Funding; Forty Seven Inc.: Research Funding; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board, Research Funding; Kura: Research Funding; Kyowa: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board; Merck: Research Funding; Astra Zeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board; Celgene: Research Funding; Autolus: Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board; Millenium: Research Funding; Agensys: Research Funding; Infinity: Research Funding; Regeneron: Research Funding; Celgene: Research Funding; Gilead/Kite: Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board, Research Funding; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board. Bartlett:KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; ImaginAB: Research Funding; Celgene: Research Funding; Pharmacyclics: Research Funding; Pharmacyclics: Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Acerta: Membership on an entity's Board of Directors or advisory committees; Millennium: Research Funding; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Meyers Squibb: Research Funding; Immune Design: Research Funding; Astra Zeneca: Research Funding; Forty Seven: Research Funding; Affimed: Research Funding; Genentech: Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; Merck & Co: Research Funding; Janssen: Research Funding. Straus:Onco Tracker: Consultancy; Roch China: Speakers Bureau; Memorial Sloan Kettering Cancer Center: Employment; JUNO: Consultancy; Medical Crossfire: Speakers Bureau; DAVA Oncology: Consultancy, Honoraria; Bayer: Consultancy; InPractice Elselvier: Consultancy; Millenium (Takeda): Consultancy, Research Funding; Seattle Genetics: Consultancy. Sureda:BMS: Consultancy, Honoraria; Sanofi: Honoraria; Roche: Honoraria; Takeda: Consultancy, Honoraria, Speakers Bureau; Merck: Consultancy, Honoraria. Hutchings:Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche/Genentech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Dlugosz-Danecka:Servier: Consultancy; Roche: Consultancy. Engley:Seattle Genetics: Employment. Fenton:Seattle Genetics, Inc.: Employment, Equity Ownership. Liu:Millennium Pharmaceuticals Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Miao:Millennium Pharmaceuticals Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Jolin:Takeda Pharmaceuticals International Co.: Employment. Gautam:Millennium Pharmaceuticals, Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Radford:Novartis: Consultancy, Speakers Bureau; Celgene: Research Funding; Pfizer: Research Funding; GlaxoSmithKline: Equity Ownership; Takeda: Consultancy, Research Funding, Speakers Bureau; AstraZeneca: Equity Ownership; Seattle Genetics: Consultancy, Speakers Bureau; BMS: Consultancy, Speakers Bureau; ADC Therapeutics: Consultancy, Research Funding.

Abstract Introduction This phase 1/2 study evaluated the safety and antitumor activity of brentuximab vedotin (BV) administered in combination with nivolumab (Nivo) in adult patients (pts) with relapsed/refractory classic Hodgkin lymphoma (R/R cHL) who have failed frontline therapy (NCT02572167). Results from Parts 1 & 2 have been previously reported, wherein safety, efficacy, and biomarkers consistent with immune activation were observed in pts with R/R cHL (Herrera et al., Blood 2018). In Part 3, patients were treated with BV + Nivo on Day 1 of each cycle. In contrast, pts in Parts 1 & 2 received BV on C1D1 and Nivo on C1D8 with concurrent admin on subsequent cycles. Herein we present safety, efficacy, and biomarker results for Part 3 and updated progression free survival (PFS) from Parts 1 & 2. Methods Pts in Parts 1 & 2 received up to four 21-day cycles of staggered dosing (day 1 BV 1.8 mg/kg, day 8 Nivo 3 mg/kg in Cycle 1) and concurrent thereafter, with steroid and antihistamine premedication. Pts in Part 3 received up to four 21-day cycles of concurrent BV + Nivo on Day 1 with antihistamine premedication. Following Cycle 4 response assessment (Lugano Classification Revised Staging System with the incorporation of the Lymphoma Response to Immunomodulatory Therapy Criteria [LYRIC, 2016]) responding pts were eligible to undergo autologous stem cell transplant (ASCT). Results 30 pts were treated in Part 3 and all were evaluable for efficacy. Pt characteristics included the following: median age 31.5 yrs (range; 20 - 66), 63% female, 93% prior ABVD, 37% primary refractory HL, 30% relapsed within 1year of frontline therapy, 30% with extranodal disease and 17% with bulky disease at enrollment. 28 pts completed all 4 cycles. 1 pt discontinued treatment (tx) due to an adverse event (AE; Grade 3 [G3] elevated Gamma-Glutamyltransferase) and 1 pt due to progressive disease (PD). The latter pt eventually died due to PD. All pts are off tx and have been observed through the safety reporting period. 37% of pts experienced a G3 or higher tx emergent AE prior to ASCT. 30% of the pts experienced infusion related reactions (IRRs), which occurred most frequently during Cycle 2. Potential G3 or higher immune-related AEs (IRAEs), excluding IRRs, occurred in 2 pts, one of whom required steroids for G4 pneumonitis, which subsequently resolved. Among the 30 efficacy evaluable pts, the complete response (CR) rate was 80% (24/30), with an objective response rate (ORR) of 93%. 47% of pts (14) had a Deauville ≤2, and 17% (5) had Deauville 3. 5 pts with CR had a Deauville >3 and met LYRIC criteria for IR-2. 4/5 pts had a negative follow-up biopsy that confirmed CR and in 1 pt the PET finding was considered to be a false positive as contrast enhanced CT did not reveal any abnormality. All 5 pts proceeded directly to ASCT and remain in CR at follow-up. Among all treated patients, 25 went directly to ASCT after completing BV + Nivo tx with a median 6.8 x 106 CD34+ cells/kg (range 1-20) collected. Median times to neutrophil and platelet engraftment were 12 and 14 days, respectively. 4 pts required additional salvage therapy subsequent to study tx. Patients were followed for a median of 6 months from ASCT (N=25, range 0.8-8.8) and 10 months from first dose (N=30, range 1.8-12.7). The estimated 9-month PFS rate in all-treated pts was 88%. This is comparable to all-treated pts in Parts 1 & 2, whose estimated 9 and 15 month PFS were 86% and 82%, respectively (Fig 2). Biomarker testing was performed on peripheral blood samples, included immunophenotyping, serum cytokine analysis, and TCRβ sequencing. Concurrent dosing of BV+ Nivo resulted in increased levels of both activated and dividing CD4+ and CD8+ T cells, as well as increased regulatory T-cells and circulating plasmablasts. Cytokines and chemokines associated with innate and adaptive immune activation, including Type I and Type II interferons, IL-18, and IP-10, were significantly upregulated following BV + Nivo, while TARC levels were significantly diminished following therapy. TCRβ sequencing revealed clonal expansion in the periphery following BV + Nivo. Conclusion A concurrent dosing schedule of BV + Nivo was well tolerated with a high CR rate of 80%. Biomarkers evaluated in Part 3 indicate immune activation in the periphery following BV + Nivo. Cumulatively, the results in Part 3, along with the durable remissions noted in Parts 1 & 2, support BV + Nivo combination as an encouraging first salvage therapy prior to ASCT in pts with R/R cHL. Disclosures Advani: Forty Seven: Research Funding; Infinity: Research Funding; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board, Research Funding; Gilead/Kite: Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board; Roche/Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board, Research Funding; Merck: Research Funding; Agensys: Research Funding; Millenium: Research Funding; Janssen: Research Funding; Celgene: Research Funding; Autolus: Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Kura: Research Funding; Kyowa: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board; Bayer: Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board; Regeneron: Research Funding; Astra Zeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board; Cell Medica: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Other: Participated in an advisory board, Research Funding. Moskowitz:Bristol Myers-Squibb: Consultancy, Research Funding; Incyte: Research Funding; Takeda: Honoraria; Merck: Research Funding; ADC Therapeutics: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding. Bartlett:Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees. Vose:Celgene: Research Funding; Legend Pharmaceuticals: Honoraria; Bristol Myers Squibb: Research Funding; Merck Sharp & Dohme Corp.: Research Funding; Incyte Corp.: Research Funding; Roche: Honoraria; Novartis: Honoraria, Research Funding; Seattle Genetics, Inc.: Research Funding; Acerta Pharma: Research Funding; Abbvie: Honoraria; Epizyme: Honoraria; Kite Pharma: Research Funding. Ramchandren:Merck: Research Funding; Bristol-Myers Squibb: Consultancy; Seattle Genetics: Consultancy, Research Funding; Pharmacyclics LLC an AbbVie Company: Consultancy, Research Funding; Janssen: Consultancy, Research Funding. Feldman:Johnson and Johnson: Speakers Bureau; Celgene: Speakers Bureau; Pharmacyclics: Speakers Bureau; Seattle Genetics: Research Funding, Speakers Bureau; Portola: Research Funding; Janssen: Speakers Bureau; KITE: Speakers Bureau. LaCasce:Seattle Genetics: Consultancy, Honoraria; Bristol-Myers Squibb: Other: Data safety and monitoring board; Research to Practice: Speakers Bureau; Humanigen: Consultancy, Honoraria. Christian:Acerta: Research Funding; Merck: Research Funding; Bristol-Myers Squibb: Research Funding; Immunomedics: Research Funding; Celgene: Research Funding; Seattle Genetics: Research Funding; Genentech: Membership on an entity's Board of Directors or advisory committees, Research Funding. Ansell:LAM Therapeutics: Research Funding; Pfizer: Research Funding; Seattle Genetics: Research Funding; Regeneron: Research Funding; Merck & Co: Research Funding; Bristol-Myers Squibb: Research Funding; Celldex: Research Funding; Trillium: Research Funding; Affimed: Research Funding; Takeda: Research Funding. Moskowitz:Celgene: Consultancy; Merck & Co: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; Pharmacyclics: Research Funding; Seattle Genetics: Consultancy, Research Funding. Fenton:Seattle Genetics, Inc.: Employment, Equity Ownership. Ogden:Seattle Genetics, Inc: Employment, Equity Ownership. Taft:Seattle Genetics: Employment, Equity Ownership. Zak:Seattle Genetics: Employment, Equity Ownership. Sacchi:Bristol-Myers Squibb: Employment, Equity Ownership. Galderisi:Seattle Genetics: Employment, Equity Ownership. Herrera:Immune Design: Research Funding; Merck, Inc.: Consultancy, Research Funding; KiTE Pharma: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Seattle Genetics: Research Funding; AstraZeneca: Research Funding; Pharmacyclics: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; Gilead Sciences: Research Funding.

Abstract Background:The role of radiation therapy (XRT) for advanced stage Hodgkin lymphoma (HL) is controversial. In the HD15 trial, the German Hodgkin Study Group (GHSG) administered XRT for PET-positive residual disease ≥2.5 cm at least 2 weeks after completion of chemotherapy and showed 91.5 % in-field control rate with a median follow-up of 102 months (Engert, A; personal communication). However, there is no comparison arm where patients with PET-positive residual disease ≥2.5 cm did not receive XRT. SWOG S0816 was a US intergroup trial utilizing ABVD-based therapy with response adaptation based on interim PET imaging; XRT was not allowed per protocol, and counted as an event. In this analysis, we identified patients in S0816 who would have met HD15 criteria for XRT, but did not receive XRT per design. We then modeled the potential impact of XRT on disease control. Patients and Methods:Of 336 eligible and evaluable HIV-negative patients enrolled in S0816, 49 had an end-of-treatment PET (termed "PET3," to be done 6-8 weeks after completion of chemotherapy) that was positive (i.e. Deauville 4-5) upon central review. We simulated the progression free survival (PFS) if XRT had been delivered per HD15 criteria (PET positive disease and ≥2.5 cm), evaluating by assumptions of 50, 80 and 90% control of the disease within the XRT fields. Receiver operating characteristics (ROC) analyses were performed with additional size cut-off points of 2.0 and 1.5 cm. Results:The median follow-up for the 49 PET3 positive patients was 71 months (range 9.7-92.6). For these 49 patients, the observed landmark PFS at 2 years after the date of PET3 was 30.6%. Twenty-four (49%), 33(67%), and 40 (82%) of the 49 patients had at least one site of disease that met the HD15 criteria for XRT with ≥2.5 cm, ≥2.0 cm, and ≥1.5 cm size cut-offs respectively. Sixteen, 19, and 25 patients had disease progression respectively from each group at median of 1.4-1.5 months. Twelve, 12, and 15 patients had relapses limited to the sites that would have been radiated following HD15 criteria with ≥2.5 cm, ≥2.0 cm, and ≥1.5 cm respectively. Estimated landmark PFS at 2 years for the 49 PET3 positive patients assuming 50, 80, and 90 % control of the disease within the radiated sites following HD15 guideline with ≥2.5 cm, ≥2.0 cm, and ≥1.5 cm cut-off are summarized in columns A, B, and C of the table respectively. For the entire group of 336 patients, the observed PFS at 2 years was 79%. Estimated 2-year PFS for the entire group of 336 patients assuming 50, 80, and 90 % control of the disease within the radiated sites following HD15 guideline with ≥2.5 cm, ≥2.0 cm, and ≥1.5 cm cut-off are in columns D, E, and F of the table respectively. Conclusion: Among the PET3 positive patients, consolidation XRT per HD15 criteria with cut-off points of 2.5, 2.0, and 1.5 cm could have raised the 2-year PFS by 12-28 % assuming 50-90% local control within radiated sites. However, the improvement in PFS is more moderate at 1.6-3.9 % if we consider the entire cohort of 336 patients. Although there may be some gain in PFS as the cut-off point is lowered by our ROC analysis, one needs to consider the trade-off against potentially increasing normal tissue toxicity as more sites are irradiated. Table. Table. Disclosures Brem: Pharamcyclics: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Genetech: Membership on an entity's Board of Directors or advisory committees; Celgene: Speakers Bureau; Bayer: Membership on an entity's Board of Directors or advisory committees. Bartlett:Merck & Co: Research Funding; Forty Seven: Research Funding; Celgene: Research Funding; Immune Design: Research Funding; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; ImaginAB: Research Funding; Janssen: Research Funding; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Acerta: Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; Millennium: Research Funding; Genentech: Research Funding; Astra Zeneca: Research Funding; Pharmacyclics: Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Meyers Squibb: Research Funding; Affimed: Research Funding; Novartis: Research Funding; Pharmacyclics: Research Funding. Evens:Seattle Genetics, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Affimed: Consultancy; Janssen: Consultancy; Tesaro: Research Funding; Bayer: Consultancy; Acerta: Consultancy; Pharmacyclics International DMC: Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy. Rimsza:NanoString: Other: Inventor on the patent for the Lymph2Cx assay. Leonard:Novartis: Consultancy; Celgene: Consultancy; MEI Pharma: Consultancy; AstraZeneca: Consultancy; ADC Therapeutics: Consultancy; United Therapeutics: Consultancy; BMS: Consultancy; Biotest: Consultancy; Sutro: Consultancy; Karyopharm: Consultancy; Juno: Consultancy; Gilead: Consultancy; Genentech/Roche: Consultancy; Pfizer: Consultancy; Bayer: Consultancy. Kahl:Seattle Genetics: Consultancy; Genentech: Consultancy; Acerta: Consultancy; AstraZeneca: Consultancy; Abbvie: Consultancy; ADC Therapeutics: Consultancy; CTI: Consultancy; Gilead: Consultancy; Juno: Consultancy; Celgene: Consultancy. Smith:BMS: Consultancy; Portola: Honoraria. Friedberg:Bayer: Honoraria.

Abstract PURPOSE Urgency to initiate therapy has to be weighed against the time required for screening and consenting to enroll a patient onto a clinical trial. Exclusion of patients with rapidly progressive or symptomatic disease may lead to selection of patients with less aggressive disease. We recently identified that a short diagnosis to treatment interval (DTI) is associated with adverse clinical factors and inferior outcome in patients with diffuse large B-cell lymphoma (DLBCL) (Maurer et al, JCO 2018); shorter time to treatment was also found to be associated with outcome in other aggressive lymphomas, including mantle cell lymphoma (MCL), in the National Cancer Database (Olszewski et al, BJH 2018). Here we assess the association of DTI with clinical variables and outcome in MCL from an observational cohort with validation in patients enrolled on an NCTN clinical trial. PATIENTS AND METHODS Newly diagnosed patients with MCL were prospectively enrolled in the University of Iowa/Mayo Clinic Lymphoma SPORE Molecular Epidemiology Resource (MER), now a subcohort of the Lymphoma Epidemiology of Outcomes (LEO) Cohort Study. Patients initially managed with observation were excluded. DTI was defined as the time in days from date of first lymphoma-containing biopsy to the initiation of therapy. Associations of DTI with clinical factors and outcome were examined using a 14 day split based on the previous MER study of DTI in DLBCL. Odds ratios (OR) and Cox model hazard ratios (HR) are reported. Outcome was assessed using event-free survival (EFS) where events were defined as progression/relapse, initiation of new anti-lymphoma therapy, or death due to any cause. A validation cohort was assembled from patients enrolled in CALGB (Alliance) clinical trial 50403. Protocol therapy was high dose chemotherapy with autologous hematopoietic stem cell transplantation (ASCT) consolidation and post-ASCT rituximab followed by bortezomib as either consolidation or maintenance. DTI was defined as time from diagnosis to study registration and outcome was assessed using progression-free survival (PFS) as defined on the clinical trial. RESULTS 271 patients with MCL enrolled in the MER from 2002-2015 and initiated treatment within 100 days of diagnosis. Median age at diagnosis was 64 years (range 36-76), 211 (78%) were male, and 92% were stage III-IV; MIPI was Low (41%), Intermediate (36%) and High (23%). Induction therapy was R-CHOP based (50%), B-R based (16%), HyperCVAD based (8%), 2-CDA based (11%), and other (15%). Median EFS of the cohort was 41 months (95% CI: 34-46). Median DTI was 26 days (IQR: 14-38) and 28% enrolled within 14 days of diagnosis, exhibiting a longer DTI than DLBCL patients enrolled in the MER during the same time period. Short DTI (0-14 days) was associated with adverse clinical factors including ECOG PS 2-4 (OR=5.74, 95% CI: 2.51-13.1, p<0.0001), elevated LDH (OR=2.30 95% CI: 1.25-4.22, p=0.0072), and higher MIPI score (OR=1.48, 95% CI: 1.04-2.07, p=0.025) but was not significantly associated with age, sex, B-symptoms, or stage (all p>0.30). Short DTI was also associated with inferior EFS (HR=1.78, 95% CI: 1.27-2.49, p=0.0008) which remained significant after adjusting for MIPI score (HR=1.72, 95% CI: 1.23-2.41, p=0.0016). In the validation cohort, 144 patients enrolled on 50403 within 100 days of diagnosis from 2006-2010. Median age at diagnosis was 59 years (range 29-69), 77% were male, and 97% were stage III-IV; MIPI was Low (51%), Intermediate (31%) and High (17%). Median PFS of the cohort was 84 months (95% CI: 50-109). Median DTI was 35 days (IQR: 22-46) and 11% enrolled within 14 days of diagnosis. Short DTI (0-14 days) was associated with PS (OR=9.00, 95% CI: 1.18-69.0, p=0.034) and) higher MIPI score (OR=2.09, 95% CI: 1.08-4.04, p=0.029) but not elevated LDH (OR=1.27, 95% CI: 0.43-3.74, p=0.66). Short DTI was associated with inferior PFS (HR=2.21, 95% CI:1.19-4.09, p=0.011) which remained clinically significant after adjusting for MIPI score (HR=1.85, 95% CI: 0.98-3.47, p=0.056). CONCLUSION A short diagnosis-to-treatment interval is strongly associated with adverse clinical factors and poor outcome in newly diagnosed MCL in the MER. Clinical trials are encouraged to facilitate enrollment of patients with short DTI to avoid potential selection bias. Support: U01 CA195568, P50 CA097274, U10CA180821, U10CA180882; ClinicalTrials.gov Identifier: NCT00310037 (CALGB 50403) Figure. Figure. Disclosures Maurer: Celgene: Research Funding; Nanostring: Research Funding; Morphosys: Research Funding. Kaplan:Bayer Pharmaceuticals: Consultancy. Cohen:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Research Funding; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees; Infinity Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Millennium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; BioInvent: Consultancy; Takeda: Research Funding. Martin:Gilead: Consultancy; Kite: Consultancy; Seattle Genetics: Consultancy; AstraZeneca: Consultancy; Janssen: Consultancy; Bayer: Consultancy. Kahl:Abbvie: Consultancy; AstraZeneca: Consultancy; Gilead: Consultancy; Acerta: Consultancy; Juno: Consultancy; Celgene: Consultancy; Genentech: Consultancy; Seattle Genetics: Consultancy; CTI: Consultancy; ADC Therapeutics: Consultancy. Bartlett:ImaginAB: Research Funding; Bristol-Meyers Squibb: Research Funding; Novartis: Research Funding; Immune Design: Research Funding; Janssen: Research Funding; Merck & Co: Research Funding; Forty Seven: Research Funding; Novartis: Research Funding; Pharmacyclics: Research Funding; Affimed: Research Funding; Astra Zeneca: Research Funding; Pharmacyclics: Research Funding; Acerta: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; Millennium: Research Funding; Genentech: Research Funding; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Cerhan:Celgene: Research Funding; Jannsen: Other: Scientific Advisory Board; Nanostring: Research Funding. Leonard:Karyopharm: Consultancy; Biotest: Consultancy; Bayer: Consultancy; Pfizer: Consultancy; ADC Therapeutics: Consultancy; Novartis: Consultancy; AstraZeneca: Consultancy; Juno: Consultancy; BMS: Consultancy; Sutro: Consultancy; MEI Pharma: Consultancy; Genentech/Roche: Consultancy; Celgene: Consultancy; Gilead: Consultancy; United Therapeutics: Consultancy.