Citations

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 - IMIDs are critical in the treatment of multiple myeloma (MM). Unfortunately, many patients become resistant and this is a major challenge in MM therapy. IMID resistance can be caused by CRBN mutations (rarely) and by upregulation of specific antioxidative mechanisms. We hypothesized that measuring baseline antioxidative capacity might be a useful predictor of IMID sensitivity in the clinic. Methods - To develop a quantitative assay for determining cellular antioxidative capacity of MM cells we measured total cellular oxidized flavin adenine dinucleotide (FAD) after treatment with H2O2. FAD has auto-fluorescent properties that can be measured via flow cytometry. Cells with high antioxidative capacity generate more FAD, and cells with low anti-oxidative capacity generate less FAD. MM cells with an increase in FAD after H2O2 were considered IMID resistant and those with no change in FAD were considered IMID sensitive (Figure 1). Clinical IMID resistance/sensitivity was defined clinically during blinded retrospective review, with disease progression based on the IMWG criteria. After blinded review of clinical outcomes, the patient flow cytometry results were disclosed to evaluate the predictive value of the flow cytometry assay for detection of IMID resistance. Results - Of 40 patients who underwent testing, 26 were IMID resistant via flow and were considered as being clinical resistant 17 (65%). Conversely, 14 patients were IMID sensitive via flow and 12 (86%) were considered to be clinical sensitive. There was a significant correlation between clinical assessment and flow cytometry in determination of IMID resistance patterns (Table 1). The sensitivity and specificity of our assay was 89% and 57% with a positive and negative predictive value of 65% and 86% respectively. A limitation of our clinical assessment was that 16 patients (38%) were treated with combination therapy; IMIDs plus a proteasome inhibitor or a monoclonal antibody. Of the 11 patients with discordant results by flow and clinical outcome, 7 (64%) were not on therapy at the time of testing and 6 (55%) had flow testing on the bone marrow sample performed on day 100 following an autologous transplant. Two (7%) of the 29 patients with correlative results were off all therapy at the time of testing, 1 with testing on the day 100 marrow sample after transplant. Conclusions - This early testing of our assay shows promising results predicting clinical sensitivity via our flow based assay. The testing demonstrates a high sensitivity and negative predictive value, with less ability to assess for resistance. However, there were limitations to this study. The majority of patients with discordant results were off IMID therapy at the time of flow cytometry and many of these were assessed on transplant day 100 marrow samples. Depth of measureable residual disease was not readily available on all marrow samples tested. It is probable that flow testing for IMID resistance is inaccurate in patients with deeper responses to therapy, especially those who are minimum residual disease (MRD) negative. Additionally, several patients were on combination IMID, proteasome inhibitor, and monoclonal antibody. It is possible that clinical IMID resistance was not detected due to the anti-MM activity of the additional therapies. Additional larger scale prospective studies are needed to validate these findings as this method of testing could potentially provide providers with powerful information allowing them to personalize therapy for their patients. Disclosures Fonseca: Mayo Clinic: Employment; Amgen: Consultancy.

Abstract Background: The selective AURKA inhibitor alisertib (MLN8237) exhibits disease modifying activity in murine models of myelofibrosis by eradicating atypical megakaryocytes resulting in reduction of marrow fibrosis (Nat Med 2015). Here, we present long term follow-up results from the investigator initiated pilot study of alisertib in patients with myelofibrosis (clinical trials.gov Identifier NCT 02530619). Methods: 24 patients with DIPSS intermediate 1, intermediate-2, or high risk myelofibrosis who were in need of therapy, refractory/intolerant or unlikely to respond to JAK inhibitors with neutrophil count ≥ 1 x109/L, and platelet count ≥ 50 x109/L, received alisertib (provided by Millennium Pharmaceuticals Inc) at a dose of 50 mg twice daily for one week every 21 days. Toxicity assessment was performed by the standard common terminology criteria (Version 4.0). Response was assessed by the international working group for myelofibrosis research and treatment (IWGMRT) criteria. Correlative studies included assessments of JAK2V617F, CALR, and MPL mutant allele burden, degree of fibrosis and GATA1 expression in bone marrow samples obtained pre and post therapy. Results: We enrolled 17 patients with primary myelofibrosis, 4 with post essential thrombocythemia myelofibrosis and 3 with post polycythemia vera myelofibrosis. Median age was 72 years with 66% males. 79% of patients were DIPSS intermediate risk, and the remainder were high risk with 15 patients (62.5%) having received prior JAK inhibitor therapy. Driver mutational status was as follows; 58% JAK2V617F, 29% CALR, and 13% MPL mutated. At study entry, 54% of patients demonstrated palpable splenomegaly ≥ 5 cm below the left costal margin, 54% were transfusion dependent with all patients experiencing constitutional symptoms. At the time of data cut-off, patients received a median of 7.5 cycles (range; 1-29 cycles) of therapy. The 7 patients presently on study have received a median of 23 cycles (range; 8-29 cycles). Reasons for treatment discontinuation included progressive disease/lack of response in 11 (65%) patients, toxicity in 4 (24%) patients and refusal of further therapy in 2 (11%) patients.Safety and Efficacy assessments The most common treatment-emergent grade 3/4 adverse events included neutropenia (42%), thrombocytopenia (29%) and anemia (21%), with 4% each experiencing neutropenic fever, diarrhea, vertigo, elevated creatinine and elevated alanine aminotransferase. 22 patients were considered for response evaluation with 4 of 14 patients (29%) with palpable splenomegaly ≥ 5 cm achieving a spleen response, 1 of 13 patients (8%) becoming transfusion independent, and 5 of 22 patients (23%) experiencing symptom response with ≥ 50% reduction in the MPN-SAF total symptom score. However, when response assessment was restricted to 13 patients who had received a minimum of 5 cycles of therapy, spleen responses were observed in 4 of 7 (57%) patients, 1 of 5 (20%) achieved transfusion independence and 5 of 13 (38%) achieved symptom response. All patients presenting with leukocytosis (n=4) and thrombocytosis (n=2) had resolution with therapy. Of the 7 patients presently on study, four patients continue to demonstrate symptom response, two patients with both spleen and symptom response, and another patient with sustained anemia response. Correlative assessments We compared the intensity of staining of GATA1, a factor that is required for maturation, in sequential bone marrow biopsies from six patients at baseline and after a minimum of five cycles and observed a striking increase in the numbers of GATA1-positive megakaryocytes in five of six cases (Figure 1a). In addition, we observed a one grade reduction in marrow fibrosis in 4 of 6 paired samples (Figure 1b). This reduction in fibrosis was accompanied by sustained responses to the drug. Finally, we compared JAK2, MPL or CALR mutant allele burden in eight paired baseline and cycle 5 or 6 samples and observed decreases in 4 of 8 patients (Figure 1c). Conclusions: Alisertib is safe and well tolerated in patients with myelofibrosis with prolonged administration up to 1.7 years. In addition to providing clinical benefit, alisertib restored normal morphology and GATA1 expression in atypical megakaryocytes and reduced marrow fibrosis and mutant allele burdens. These findings demonstrate that AURKA inhibition should be further explored as a therapeutic option in myelofibrosis. Figure 1. Figure 1. Disclosures Swords: AbbVie: Employment. Watts:Jazz Pharma: Consultancy, Speakers Bureau; Takeda: Research Funding. Frankfurt:Celgene, Jazz, Agios: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AbbVie: Membership on an entity's Board of Directors or advisory committees. Altman:Cyclacel: Other: payment to the institution to conduct clinical trial work; Epizyme: Other: payment to the institution to conduct clinical trial work; Ariad: Other: payment to the institution to conduct clinical trial work; Bayer: Other: payment to the institution to conduct clinical trial work; Celator: Other: payment to the institution to conduct clinical trial work; FujiFilm: Other: payment to the institution to conduct clinical trial work; Celgene: Membership on an entity's Board of Directors or advisory committees, Other: payment to the institution to conduct clinical trial work; Agios: Other: Payment to the institution to conduct the trial ; Astellas Pharma: Other; Genetech: Other: Payment to the institution to conduct clinical trial work; Syros: Membership on an entity's Board of Directors or advisory committees; Incyte: Other: payment to the institution to conduct clinical trial work; GSK: Other: payment to the institution to conduct clinical trial work; Immune Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Janssen Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Boeringer Ingelheim: Other: payment to the institution to conduct clinical trial work; Novartis: Membership on an entity's Board of Directors or advisory committees; Pfizer: Other: payment to the institution to conduct clinical trial work. Rampal:Celgene: Honoraria; Stemline: Research Funding; Incyte: Honoraria, Research Funding; Constellation: Research Funding; Jazz: Consultancy, Honoraria. Giles:Actuate Therapeutics Inc: Employment, Equity Ownership. Crispino:Forma Therapeutics: Research Funding; Scholar Rock: Research Funding.

Abstract Introduction: Venetoclax (Ven), an oral agent that targets the antiapoptotic protein, BCL-2, has demonstrated efficacy, as monotherapy and combined with proteasome inhibitor (PI) bortezomib, in relapsed/refractory (R/R) multiple myeloma (MM). We report preliminary safety and efficacy data for Ven combined with the second generation PI carfilzomib (K) and dexamethasone (VenKd) in R/R MM. Methods: In this ongoing phase 2, dose escalation study (NCT02899052), patients with R/R MM and no prior K exposure received VenKd on 28-d cycles in 4 dose finding and one expansion cohorts: Ven 400 mg/day + K 27 mg/m2 Day 1, 2, 8, 9, 15, 16 + dex 40 mg Day 1, 8, 15, 22 (Cohort 1), same regimen but with Ven 800 mg/day (Cohort 2), Ven 800 mg/day + K 70 mg/m2 Day 1, 8, 15 + dex 40 mg Day 1, 8, 15, 22 (Cohort 3/expansion cohort), or Ven 800 mg + K 56 mg/m2 Day 1, 2, 8, 9, 15, 16 + dex 40 mg Day 1, 2, 8, 9, 15, 16, 22, 23 (Cohort 4). Treatment continued until progressive disease (PD) or unacceptable toxicity. Results: As of June 11, 2018, 42 patients were enrolled. The median age was 66.5 years (min, max: 37, 79), 63% had ISS II/III disease, and 8 patients (19%) had t(11;14). Patients received a median of 2 prior therapies (range: 1 - 3), 93% had received prior PI (50% refractory), 62% were refractory to immunomodulatory therapies, and 33% double refractory. At the data cut off, 29 patients were still active and had completed ≥2 cycles and 13 patients discontinued with the primary reason being disease progression (n=4), death (n=3), physician decision (n=2), withdrawal of consent (n=2), lack of efficacy (n=1), and AE (n=1). All patients experienced at least one AE, and grade 3/4 AEs experienced by >10% of subjects included: decreased lymphocyte count (26%), decreased neutrophil count (14%), and hypertension (12%). Thirteen subjects experienced at least one serious AE. Maximum tolerated dose was not reached and Ven 800 mg/day + K 70 mg/m2 was selected for expansion. Ven mean (% coefficient of variation) maximum plasma concentration (Cmax) and area under the plasma concentration-time curve over 24 hours (AUC24) on Cycle 1 Day 15 were 2.7 (57) mg/mL and 33.1 (54) mg×h/mL, respectively, at 400 mg venetoclax (n=4); and were 2.42 (53) mg/mL and 38.7 (51) mg×h/mL, respectively, at 800 mg venetoclax (n=13) in the dose escalation cohorts. The overall response rate (ORR) was 78% and the very good partial response (VGPR) or better rate was 56% (Table). Median time from first dose to the data cut or discontinuation was 5.7 months (range: 0.9 - 16.3) and the median time to first response was 1.9 months (95% CI: 0.9, 9.2). ORRs for subgroups of interest are reported in the Table. Conclusions: The combination of VenKd appears tolerable with no new safety signals or changes in Ven pharmacokinetics. VenKd shows promising preliminary efficacy in R/R MM patient subgroups. Response rates were comparable in all high risk subgroups and overall population. However, the subset of patients with t(11;14) had the highest response. Overall, these results demonstrate that VenKd is a safe and efficacious regimen in R/R MM and support the continued study of VenKd. Disclosures Costa: Abbvie: Research Funding; BMS: Research Funding; Karyopharm: Research Funding; Amgen: Honoraria, Research Funding; Sanofi: Honoraria; Celgene: Honoraria, Research Funding; Janssen: Research Funding. Stadtmauer:Celgene: Consultancy; AbbVie, Inc: Research Funding; Janssen: Consultancy; Takeda: Consultancy; Amgen: Consultancy. Morgan:Bristol-Myers Squibb: Consultancy, Honoraria; Janssen: Research Funding; Takeda: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding. Kovacsovics:Amgen: Honoraria, Research Funding; Abbvie: Research Funding. Jakubowiak:Takeda: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; SkylineDx: Consultancy, Honoraria; Adaptive Biotechnologies: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; Karyopharm: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Kaufman:Roche: Consultancy; BMS: Consultancy; Karyopharm: Other: data monitoring committee; Janssen: Consultancy; Abbvie: Consultancy. Mobasher:Genentech Inc: Employment; F. Hoffmann-La Roche Ltd: Other: Ownership interests non-PLC. Freise:AbbVie, Inc: Employment, Equity Ownership. Ross:AbbVie, Inc: Employment, Equity Ownership. Pesko:AbbVie, Inc: Employment, Equity Ownership. Munasinghe:AbbVie, Inc: Employment, Equity Ownership. Gudipati:AbbVie, Inc: Employment, Equity Ownership. Mudd:AbbVie, Inc: Employment, Equity Ownership. Bueno:AbbVie, Inc: Employment, Equity Ownership. Kumar:Oncopeptides: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Abstract Background : Ibrutinib, a Bruton's tyrosine kinase (BTK) inhibitor was approved for the treatment of Waldenstrom Macroglobulinemia (WM) in January, 2015 based on the results of a clinical trial of 63 previously-treated patients with WM. Data on outcomes with ibrutinib outside of clinical trials are limited. Methods : Medical records of patients with WM seen consecutively between 02/01/2015 and 06/01/2018 at Mayo Clinic, MN, FL and AZ were reviewed and those treated with ibrutinib at any point during their disease were included. Refractoriness to prior therapy was defined as disease progression on therapy or within 2 months of stopping treatment. The response rates were assessed by WM VI International Workshop Criteria. Adverse events were graded using National Cancer Institute Common Toxicity Criteria for Adverse Events (AEs) v4.03. All time-to-event analyses were performed from the time of initiation of ibrutinib. Results : Eighty patients [previously treated, n=67 (84%), treatment-naïve, n=13 (16%)] received ibrutinib for active WM. Median follow-up was 18 months (95% CI: 12-19) and the median overall survival (OS) was not reached (NR) (95% CI: 27-NR) for the entire cohort at the date of last follow-up. The median age was 67 years (range: 50-88) and the median ECOG performance score was 1 (range: 0-3) at the time of ibrutinib initiation. Median lines of therapies prior to ibrutinib for the previously-treated patients was 2 (range: 1-9) and 35 patients (44%) had received ≥3 prior lines of therapy. Of the 80 patients, 52 patients (43 previously treated, 9 treatment-naïve) had data for response assessment. The baseline characteristics and laboratory parameters at initiation of ibrutinib are outlined in Table 1a and prior therapies are mentioned in Table 1b. Overall response rate (ORR) was 90% (100% in patients with ibrutinib as primary therapy and 88% in salvage therapy setting); major-response rate (MRR) was 77%. Median time to first and best response was 2.1 months (95% CI: 1.5-3.5) and 5.4 months (95% CI: 3.5-13), respectively. Other clinically relevant endpoints and AEs related to ibrutinib therapy are outlined in Table 2 and 3, respectively. The median time-to-next therapy was 33 months (95% CI: 28-NR). At last follow-up, 25 (32%) patients had discontinued ibrutinib therapy. The reasons for discontinuation was progression (n=8), elevated liver enzymes (n=4), cognitive changes (n=1), inability to achieve better than MR (n=1), atrial fibrillation (n=3), consolidation with autologous stem cell transplantation after PR with ibrutinib (n=1), transition to hospice care due to progressive head and neck cancer (n=1), infection in lower extremity (n=1), transformation to DLBCL (n=1), blistering rash which resolved after ibrutinib discontinuation (n=1), obscure GI bleed that resolved after ibrutinib discontinuation (n=1), fatigue (n=1) and for unclear reasons recorded as treatment intolerance (n=1). Following discontinuation of ibrutinib, 21 patients received salvage therapy. Of these, data regarding the response to salvage therapy was available in 9 (43%) patients (VGPR=2, PR=3, SD=3 and progressive disease=1); median PFS from the salvage therapy following ibrutinib discontinuation was 18 months (95% CI: 2-25). Of the 4 patients who were not treated following ibrutinib discontinuation; 1 elected hospice care due to concurrent head and neck cancer progression, and the other 3 patients elected to be monitored off therapy (one had achieved SD and two had PR from ibrutinib). Fourteen patients were evaluable for IgM rebound following ibrutinib discontinuation. Of those, 5 (36%) had sudden increase in IgM level [median: 158% from the IgM level after ibrutinib discontinuation (range: 22%-1368%)] within a median of 2 months (range: 1-3 months) and 1 patient required plasmapheresis for symptomatic hyperviscosity. Four of 5 patients received salvage therapy between 0-15 months. At last follow-up, 11 patients (14%) had died of whom 3 were on ibrutinib at the time of death [CNS involvement, (n=1), causes unrelated to WM, (n=2)]. Conclusions : Ibrutinib is an effective agent in WM patients with MYD88L265Pmutation. Our data regarding outcomes in non-trial setting appear comparable to the results observed in the pivotal clinical trial. Hematologists should be aware of unique ibrutinib associated toxicities and clinically relevant IgM rebound phenomenon following abrupt discontinuation of ibrutinib. Disclosures Ailawadhi: Celgene: Consultancy; Janssen: Consultancy; Takeda: Consultancy; Pharmacyclics: Research Funding; Amgen: Consultancy. Gertz:janssen: Consultancy; Prothena: Honoraria; Medscape: Consultancy; Teva: Consultancy; celgene: Consultancy; annexon: Consultancy; Alnylam: Honoraria; Physicians Education Resource: Consultancy; spectrum: Consultancy, Honoraria; Apellis: Consultancy; Amgen: Consultancy; Abbvie: Consultancy; Ionis: Honoraria; Research to Practice: Consultancy. Kumar:Novartis: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding. Lacy:Celgene: Research Funding. Dispenzieri:Celgene, Takeda, Prothena, Jannsen, Pfizer, Alnylam, GSK: Research Funding. Witzig:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Dingli:Millennium Takeda: Research Funding; Alexion Pharmaceuticals, Inc.: Other: Participates in the International PNH Registry (for Mayo Clinic, Rochester) for Alexion Pharmaceuticals, Inc.; Alexion Pharmaceuticals, Inc.: Other: Participates in the International PNH Registry (for Mayo Clinic, Rochester) for Alexion Pharmaceuticals, Inc.; Millennium Takeda: Research Funding. Kapoor:Celgene: Research Funding; Takeda: Research Funding.