Smith, Mitchell R.

Abstract Although initial therapy of mantle cell lymphoma (MCL) is not standardized, bendamustine plus rituximab (BR) is commonly used in older patients. Rituximab (R) maintenance after induction is often used. Thus, the open-label, randomized phase 2 ECOG-ACRIN Cancer Research Group E1411 trial was designed to test 2 questions: (1) does addition of bortezomib to BR induction (BVR) and/or (2) addition of lenalidomide to rituximab (LR) maintenance improve progression-free survival (PFS) in patients with treatment-naïve MCL? From 2012 to 2016, 373 previously untreated patients, 87% aged ≥60 years, were enrolled in this trial. At a median follow-up of 7.5 years, there is no difference in the median PFS of BR compared with BVR (5.5 vs 6.4 years; hazard ratio [HR], 0.90; 90% confidence interval [CI], 0.70-1.16). There were no unexpected additional toxicities with BVR treatment compared with BR, with no impact on total dose/duration of treatment received. Independent of the induction treatment, addition of lenalidomide did not significantly improve PFS, with median PFS in R vs LR (5.9 vs 7.2 years; HR, 0.84; 90% CI, 0.62-1.15). Most patients completed the planned 24 cycles of LR at the scheduled dose. In summary, adding bortezomib to BR induction does not prolong PFS in treatment-naïve MCL, and LR maintenance was not associated with longer PFS compared with R alone after BR. Nonetheless, the >5-year median PFS outcomes in this prospective cooperative group trial indicate the efficacy of BR followed by R maintenance as highly effective initial therapy for older patients with MCL. This trial was registered at www.clinicaltrials.gov as #NCT01415752.

Abstract Tumor-associated macrophages (TAMs) within the tumor microenvironment (TME) play an important role in tumor growth and progression. TAMs have been involved in producing immunosuppressive TME via various factors; however, the underlying mechanisms remain unclear in B-cell lymphoma, including mantle cell lymphoma (MCL). We identified that chemokine receptor-1 (CCR1) is highly expressed on monocytes (Mo) and macrophages (MΦ), and CCR1 pharmacological inhibition or CCR1 siRNA abolished lymphoma-mediated Mo/MΦ migration in a chemotaxis assay. The deficiency of host CCR1 (CCR1 KO) was associated with decreased infiltration of peritoneal-MΦ compared with WT-CCR1. Functional studies indicated that the genetic depletion of CCR1 or treatment inhibited protumor MΦ (M2-like) phenotype by decreasing CD206 and IL-10 expression. Moreover, CCR1 depletion reprogrammed MΦ toward an MHCII+/TNFα+ immunogenic phenotype. Mechanistically, protumor MΦ driven–IL-10 provides a positive feedback loop to tumor-CCL3 by regulating the CCL3 promoter via STAT1 signaling. Therapeutic in vivo targeting of CCR1 with CCR1 antagonist BX-471 significantly reduced FC-muMCL1 mouse tumors in the syngeneic MCL model by the depletion of M2-TAMs and increased infiltration of cytotoxic CD8+ T cells. Our study established that CCR1 exerts a pivotal role in macrophage programming, thus shaping protumor TME and lymphoma progression. CCR1 inhibition through CCR1 antagonists may be a promising therapeutic strategy to reprogram macrophages in lymphoma-TME and achieve better clinical outcomes in patients.

7503 Background: Optimal initial therapy for mantle cell lymphoma (MCL) remains uncertain. The randomized phase 2 NCTN trial E1411 tested if progression-free survival (PFS) is prolonged by addition of bortezomib (V) (1.6 mg/m2 SC/IV days 1, 8) to bendamustine-rituximab (BVR vs BR) induction and/or by addition of lenalidomide (L) to rituximab (LR vs R) consolidation. Here we report efficacy and toxicity of induction BVR vs BR. Methods: 373 pts, accrued 2012–16, stratified by MIPI and age (≥60) received 1 of 4 arms: A) BR induction x 6 followed by R x 2 yrs, B) BVR followed by R, C) BR followed by LR or D) BVR followed by LR. Eligible pts had untreated MCL, ≥ age 18 (amended from ≥60 when S1106 for < 65 closed), ECOG PS 0-2 and adequate hematologic and organ function. Pts without progressive disease during induction proceeded to consolidation. Primary induction objective was whether adding bortezomib (BVR) (Arms B + D) to BR (Arms A + C) improves PFS, irrespective of consolidation R vs LR. Design of 360 eligible treated pts would provide 93.8% power to detect 10% improvement in 2-yr PFS from 70% hypothesized for BR, corresponding to 37.4% reduction in hazard using stratified log-rank test at 1-sided 10% alpha. Efficacy population was 179 (BVR) and 180 (BR), induction treatment completed in 144 vs 153, progressive disease during induction 6 vs 7 and registration to consolidation 140 vs 145. Results: Baseline demographics did not differ between the groups, with median age 67 (range 42-90) and 13% < 60 yr, 73% men, ECOG PS 0-1 97%, MIPI Low/Med/Hi 37/29/34%. Estimated PFS at 2 yrs 79.6% BVR (95% CI 73.8-85.9) vs 74.5% BR (95% CI 68.2-81.4) (1-sided stratified log-rank p = 0.268). With median PFS follow-up 51 mos, median PFS estimated at 64.1 and 64.0 mos. Overall response rate (ORR) for BVR was 88.9% (CR 65.5%) vs 89.5% (CR 60.5%) BR (z-test 1 sided p = 0.577 for ORR). Treatment related deaths during induction were 2 in BVR (cardiac arrest, hepatitis) and 1 in BR (tumor lysis). Grade ≥ 3 toxicities were 88.1% (163/185) BVR vs 77.5% (145/187) BR. For BVR vs BR grade ≥ 3 neutropenia occurred in 52 vs 39 pts, though febrile neutropenia (7 vs 6), anemia (7 vs 8) and thrombocytopenia (18 vs 16) did not differ. Peripheral neuropathy (PN) grade 2 was 8 sensory for BVR vs 2 sensory/1 motor for BR, while grade 3 PN was 6 sensory/1 motor for BVR vs 0 with BR. The only non-hematologic grade ≥ 3 toxicity in > 5% of pts was rash (9 vs 12 pts). Conclusions: Bortezomib did not significantly improve the primary endpoint of PFS when added to BR as initial MCL therapy. ORR and CR rates at end of induction were also similar. Follow-up continues to assess the entire treatment regimen, including consolidation R vs LR, but the PFS > 5 yrs, high ORR and MRD negativity rate (Smith et al ASH 2019) in this BR-based trial support BR as a platform for MCL induction therapy. Clinical trial information: NCT01415752.

Abstract Two death receptors, TRAIL-R1 (DR4) and TRAIL-R2 (DR5), expressed in a wide variety of cancer cell types including lymphoma, enable TRAIL (TNF related apoptosis inducing ligand), a member of the TNF ligand superfamily, to induce apoptosis. HGS-ETR1 (TRM-1, mapatumumab) is a fully human monoclonal antibody agonistic to TRAIL-R1 with preclinical evidence of anti-tumor activity in vitro and in vivo. We conducted a phase 2 multicenter study of HGS-ETR1 in 40 subjects with relapsed or refractory NHL. Patients were included on the study if they had relapsed/refractory NHL of any histologic subtype, irrespective of the number of previous treatment regimens. HGS-ETR1 was administered at 2 dose levels: 3 mg/kg (8 subjects) or 10 mg/kg (32 subjects) every 21 days in the absence of disease progression or prohibitive toxicity for up to 6 cycles. The primary endpoint was tumor response evaluated with the International Working Group Criteria after every third treatment. Responses were confirmed between 4 and 8 weeks after initial documentation of response. Secondary endpoints included safety and tolerability. The median age of subjects was 62 years (range 32–81) (24M:16F) with an ECOG performance status 0–2. Subjects had received up to 12 previous therapeutic regimens (69% received 3 or more prior regimens). Original histologic classification is presently available for 34 subjects (14 follicular, 7 diffuse large B-cell, 6 mantle cell, 1 small lymphocytic, 2 peripheral T-cell, 1 anaplastic large cell, 3 lymphomas not classified). Preliminary response data are available for all 40 subjects. 3 subjects (8%), all with follicular lymphoma, had clinical responses (1CR, 2PR). Additionally, 12/40 subjects (30%) had stable disease, and the remainder had progressive disease at the time of first evaluation. 8 subjects (7 follicular) remain on study without disease progression for &gt;5 to &gt;13 months. One subject with a PR (special permission) has continued to receive HGS-ETR1 (10 cycles to date). Subjects tolerated therapy well with no subjects discontinuing therapy due to toxicity related to drug. There have been 10 reported SAEs, 2 of which were considered possibly/probably related to HGS-ETR1 administration (shingles, fever). In conclusion, HGS-ETR1 can be safely administered to heavily treated NHL patients. Clinical responses were seen in 3/14 follicular lymphoma subjects to date. Final data for all subjects will be reported at the meeting. These data suggest that HGS-ETR1 has activity in heavily pretreated lymphoma patients and further studies in combination with agents active in lymphoma are justified.

Initial therapy for MCL is effective, but most patients eventually relapse. Validated intermediate biomarkers for MCL are important to provide early assessment of treatment efficacy, prognostic information and potentially guide consolidation. The US-Canadian Intergroup trial E1411 randomly assigned patients (pts) to receive induction with BR ± bortezomib (V), followed by consolidation with R ± L. As a planned correlative, MRD was assessed after cycle 3 (I3), end of induction (EOI) and after 4 cycles of consolidation (C4) by two methods: a research version of clonoSEQ® a next generation sequencing (NGS) MRD assay, (Adaptive Biotechnologies, Seattle, WA) that leverages multiplex PCR followed by NGS to identify and track rearrangements of IgH, V-J, D-J and IgK/L loci as well as translocations in Bcl1/2-IgH, and flow cytometry (FC) (I3 and EOI only) at a central laboratory (Mayo Clinic). While outcomes by treatment arm remain blinded, we report here the results of the MRD assessments by each method and the associated progression free survival (PFS). In E1411, 373 pts, accrued between May 2012 - Sept. 2016, were randomly assigned (stratified by MIPI and age (&lt;/≥60)) to receive BR induction x 6 followed by R for 2 years, BVR followed by R, BR followed by LR or BVR followed by LR. Eligible pts were ≥ age 18 and had untreated MCL, ECOG PS 0-2, and adequate hematologic and organ function. Of the 373 pts, 296 (79%) consented to correlatives. Of these, 255 (86%) had baseline NGS samples, and 214 were analyzable. Excluded were 6 patients that were protocol ineligible, 20 without clinical follow-up; only 7 (2.7%) patients were ineligible due to inability to identify a dominant clone necessary to follow MRD by the NGS method. At baseline pre-treatment, NGS detected a dominant clone in bone marrow (BM) or peripheral blood (PB) in 92%, with only 17 (8%) requiring study of biopsy tissue. Of the 296, 240 had baseline FC data, 9 were protocol exclusions, leaving 231 analyzable. FC detected a non-MCL monoclonal B cell lymphocytosis clone in a small number of cases. While NGS may have higher sensitivity, as FC sensitivity is 10-4, for this analysis we used that cutoff for both NGS and FC. Cohen's Kappa statistic compares concordance between MRD pairs, and p-value is from exact McNemar's test. BR-based initial MCL therapy achieved early MRD negativity (&lt; 10-4) in a high proportion of patients. Analyzing PB at mid-induction (I3): by NGS 89% MRD-, 9% MRD+ and 2% indeterminate, whereas by FC 87% MRD-, 12% MRD+ and 1% indeterminate. Concordance was high with 127 MRD- by both methods, 13 MRD+ by both, and 6 NGS-/FC+ (Kappa Statistic = 0.79, p-value = 0.031). By NGS, of 12 pts MRD+ at I3, 7 became MRD- at EOI, and 4 remained MRD+ (1 indeterminate). Analyzing at EOI: MRD- rates were 91% by NGS analysis of PB (147/161) and 90% in BM (96/107), vs 95% (174/183) by FC in PB. As some were indeterminate, only 7% were MRD+ by NGS in BM, 3% by NGS in PB and 5% by FC. In 88 informative samples with EOI NGS in both BM and PB, concordance was high, with 81 negative in both, 1 positive in both and 6 BM+/PB- (Kappa Statistic = 0.23, p-value = 0.031). Of 101 pts with data at all 3 timepoints, I3, EOI, and C4: 7 were MRD+ at I3, 5 of these were MRD- at EOI, but 2 of these 5 were again MRD+ at C4. Of 2 MRD+ EOI, 1 became MRD- at C4. By FC, of 17 patients MRD+ at I3, 11 (65%) became MRD- at EOI. MRD status correlated with progression-free survival (PFS). Due to the low MRD+ rate at EOI and C4, we focus here on MRD status at I3 (10-4 cutoff for both NGS and FC), using a landmark analysis of 4 months on study. Median PFS (Figure) for pts MRD- at I3 mid-induction was 58.9 months by either NGS or FC, while for those MRD+ by NGS it was 26.9 months, vs 29.9 months MRD+ by FC. Conclusions: Both NGS and FC were feasible to assess MRD status in this multi-center trial. Results of NGS and FC are concordant at the 10-4 cutoff. NGS can be more sensitive when adequate material is available, and analysis of this subgroup is ongoing. The high MRD- rate (≥ 90%) at EOI in this BR-based trial and MRD correlation with PFS supports its use as a platform for MCL trials, although consolidation may confound PFS. Early interim MRD testing at cycle 3 identifies a high-risk population who may benefit from alternative treatment strategies. Analysis by treatment arm with longer follow-up, as well as comparison with centrally reviewed PET/CTs included in this study, will help define the most informative method(s), cutoff values, and timing for assessing degree of response in MCL. Figure. Disclosures Smith: Astra-Zeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; EUSA: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Parekh:Foundation Medicine Inc.: Consultancy; Celgene Corporation: Research Funding; Karyopharm Inc.: Research Funding. Martin:Sandoz: Consultancy; Karyopharm: Consultancy; Teneobio: Consultancy; Celgene: Consultancy; Janssen: Consultancy; I-MAB: Consultancy. Till:Mustang Bio: Patents & Royalties, Research Funding. Leonard:Gilead: Consultancy; Akcea Therapeutics: Consultancy; Bayer Corporation: Consultancy; Genentech, Inc./F. Hoffmann-La Roche Ltd: Consultancy; BeiGene: Consultancy; Celgene: Consultancy; Akcea Therapeutics: Consultancy; Nordic Nanovector: Consultancy; ADC Therapeutics: Consultancy; Sandoz: Consultancy; MorphoSys: Consultancy; Sutro Biopharma: Consultancy; Karyopharm Therapeutics: Consultancy; Karyopharm Therapeutics: Consultancy; Merck: Consultancy; Genentech, Inc./F. Hoffmann-La Roche Ltd: Consultancy; Epizyme, Inc: Consultancy; Gilead: Consultancy; AstraZeneca: Consultancy; Epizyme, Inc: Consultancy; Bayer Corporation: Consultancy; Miltenyi: Consultancy; Celgene: Consultancy; ADC Therapeutics: Consultancy; MorphoSys: Consultancy; Sandoz: Consultancy; Miltenyi: Consultancy; AstraZeneca: Consultancy; Nordic Nanovector: Consultancy; Merck: Consultancy; BeiGene: Consultancy; Sutro Biopharma: Consultancy. Friedberg:Bayer: Honoraria, Other: Data & Safety Monitoring Committee; Acerta: Other: Data & Safety Monitoring Committee. Kahl:TG Therapeutics: Consultancy; ADC Therapeutics: Consultancy, Research Funding; Seattle Genetics: Consultancy; BeiGene: Consultancy.

Abstract Abstract 924 Background: Therapy-related myeloid neoplasia (t-MN), including myelodysplastic syndrome and acute myeloid leukemia, has been reported at a higher frequency with chlorambucil + fludarabine as compared to fludarabine alone, but has not been rigorously studied in the context of cyclophosphamide as an alkylator agent. The intergroup prospective randomized Phase 3 trial, E2997, compared FC with F alone as initial therapy for patients (pt) with chronic lymphocytic leukemia (CLL). FC therapy led to higher complete and overall response rates and longer progression-free survival at the initial analysis (Flinn et al JCO 2007). One rationale for combining F with C is that F can inhibit repair of DNA damage induced by C. FC did cause more myelosuppression that could lead to more long-term effects on myeloid hematopoietic function, including t-MN. Methods: E2997 enrolled 278 pts, 141 on FC and 137 on F. These cases were assessed for t-MN by required reporting of these events. Baseline genetic and molecular features of CLL were available through a companion lab correlative trial for 235 pts, 122 on FC and 113 on F. Results: With median follow-up of 6.4 yrs, there have been 13 (4.7%) reported cases of t-MN, 9 after FC and 4 after F. By cumulative incidence methodology, adjusting for the competing risk of death, the rates of t-MN at 7 yr are 8.2% after FC and 4.6% after F (p=0.18 by the Gray test). Median age at study entry of the t-MN pts was 60 (range 45–80) yrs vs 61 (range 33–86) yrs among those not reported to have t-MN. Median time from initial therapy to diagnosis of t-MN was 5 (range 0.7–8) yrs and did not differ between FC and F. Ten of 13 affected pts received 6 chemotherapy cycles. Additional therapy prior to occurrence of t-MN was given to only 2 of 9 FC pts, in contrast to 3 of 4 F pts. Thus, t-MN occurred in only 1 pt treated with F and no further therapy vs 7 who received FC and no further therapy. Ten of 12 pts with available cytogenetics at diagnosis of t-MN had an abnormality of chromosome 5 and/or 7, common to alkylating agent-induced t-MN, usually (n=8) with complex karyotype. Of the 9 pts with t-MN after FC, all 7 with available CLL data had lower risk IgVH mutated disease, in contrast to 1 of 4 with t-MN after F and 44% in the entire cohort. Conclusion: Our analysis suggests that a higher incidence of t-MN has occurred after FC than after F. t-MN after FC occurred most often without additional therapy and in IgVH mutated CLL which is associated with more favorable outcome. The increased incidence of t-MN after FC in this study, usually in the absence of additional treatment, suggests that FC is more leukemogenic than F. This finding emphasizes a need for longer follow-up of toxicity and survival before concluding that FC is preferable to F as the chemotherapy backbone for initial therapy of both low and high risk CLL. Disclosures: No relevant conflicts of interest to declare.

Abstract Background: Patients (pts) with refractory aggressive non-Hodgkin lymphoma (NHL) have poor outcomes with currently available therapies, with a complete response (CR) rate of 8%, a partial response (PR) rate of 18%, and median overall survival (OS) of 6.6 months (mo) as demonstrated in the 635 pt SCHOLAR-1 meta-analysis (Crump, ASCO 2016; abstract 7516). ZUMA-1 is the first multicenter trial of anti-CD19 chimeric antigen receptor (CAR) T cells in refractory, aggressive NHL (NCT02348216). The phase 1 portion of ZUMA-1 showed ongoing CRs at 12+ mos in 43% of pts (Locke, ESMO 2016; abstract 1048O). The pivotal phase 2 portion of ZUMA-1 comprises 2 cohorts based on tumor type: DLBCL (cohort 1) and primary mediastinal B-cell lymphoma or transformed follicular lymphoma (cohort 2). Here, we present results of a prespecified interim analysis from cohort 1. Methods: Pts received a target dose of 2 × 106 anti-CD19 CAR T cells/kg after a low-dose conditioning regimen of cyclophosphamide (500 mg/m2) and fludarabine (30 mg/m2) daily for 3 days. The primary endpoint is objective response rate (ORR) per 2007 IWG criteria. Key secondary endpoints include duration of response, frequency of adverse events (AEs), and levels of CAR T cells and serum cytokines. Key inclusion criteria include age ≥18 years, ECOG performance status (PS) 0-1, and refractory disease defined as progressive disease or stable disease as best response to last line of therapy, or disease progression ≤12 mos after autologous stem cell transplant (ASCT). Pts must have received a prior anti-CD20 antibody and an anthracycline-containing regimen. A prespecified interim analysis was to be conducted to determine early efficacy with a nominal alpha level of 0.017 in 50 treated pts in cohort 1 with a minimum follow-up of 3 mos. Results: In total, 111 pts from 22 institutions were enrolled and leukapheresed, and 101 pts received KTE-C19. As of August 24, 2016, 51 pts in cohort 1 were eligible for analysis. Median age was 58 years (range, 25-76), 73% were male, 71% had ECOG PS 1, 78% were refractory to ≥2 lines of therapy, 20% relapsed ≤12 mos of ASCT, and 61% were treated with ≥3 lines of prior therapy. KTE-C19 was successfully manufactured in 99% of pts enrolled. Average turnaround time from apheresis to receipt of KTE-C19 at the clinical site was 17.4 days. With an ORR of 76%, the study met the primary endpoint (P<0.0001; exact binomial test comparing observed ORR to a historical control assumption of 20%), with 47% CRs and 29% PRs. 92% of responses occurred within the 1st mo, and 39% of pts had ongoing responses (CR in 33%) at 3 mos. Responses were seen across key covariates, including refractory subgroup (refractory to chemotherapy=76%, relapse post ASCT=80%). Kaplan-Meier estimates of progression-free survival at 1 and 3 mos were 92% and 56%, respectively. The most common grade ≥3 treatment-emergent AEs were neutropenia (67%), anemia (39%), thrombocytopenia (29%), febrile neutropenia (27%), and encephalopathy (24%). Grade ≥3 cytokine release syndrome (CRS) and neurologic events occurred in 20% and 29% of pts, respectively. There was 1 grade 5 KTE-C19-related event of hemophagocytic lymphohistiocytosis. CAR T cells expanded within 14 days of KTE-C19 infusion, and peak expansion was associated with ongoing response at mo 3 (P=0.008). Pts who developed grade ≥3 neurological events had increased serum levels of IL-15 (P=0.0002), IL-6 (P=0.003); IL-10 (P=0.009) and IP-10 (P=0.0003). Cytokines/chemokines returned to baseline levels in most pts by day 28. Data from 93 pts with at least 1 mo of follow-up at the data cutoff will be presented. Conclusions: ZUMA-1 is the first reported multicenter trial of CAR T cell therapy in pts with refractory aggressive NHL. KTE-C19 induced a nearly 6-fold higher CR rate compared to historical outcomes in SCHOLAR-1. Efficacy strongly associated with peak CAR T levels. Central manufacturing, logistics, and AE management were successfully implemented across 22 sites, most with no prior CAR T therapy experience. Results from cohort 2 of ZUMA-1 are also presented (Abstract #998). KTE-C19 demonstrated significant clinical benefit in pts with no curative treatment options. Supported in part by funding from The Leukemia & Lymphoma Society Therapy Acceleration Program®. Drs Neelapu and Locke contributed equally to this study. Disclosures Neelapu: Kite Pharma: Membership on an entity's Board of Directors or advisory committees, Research Funding. Locke:Kite: Membership on an entity's Board of Directors or advisory committees. Miklos:pharmacyclics: Research Funding; Kite Pharma: Research Funding; Roche: Research Funding; Novartis: Research Funding. Jacobson:Kite: Membership on an entity's Board of Directors or advisory committees. Siddiqi:Pharmacyclics: Speakers Bureau; Janssen: Speakers Bureau; Seattle Genetics: Speakers Bureau. Lin:Mayo Clinic: Employment; Janssen: Research Funding. Timmerman:Bristol-Myers Squibb, Kite Pharma, Valor Biopharmaceuticals, Janssen: Research Funding; Seattle Genetics, Genmab, Celgene: Consultancy, Honoraria. Goy:COTA: Membership on an entity's Board of Directors or advisory committees; Janssen/Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Research funding for clinical trials through institution, Speakers Bureau; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Research funding for clinical trials through institution; Acerta: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Genentech: Other: Research funding for clinical trials through institution. Smith:Abbvie: Research Funding; Celgene: Honoraria; Spectrum: Honoraria; Genentech: Honoraria. Deol:Jazz Pharmaceuticals: Consultancy. Avivi:Tel Aviv Sourasky Medical center: Consultancy, Other: consultancy to :BMS Roche. Westin:Genentech: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Spectrum: Membership on an entity's Board of Directors or advisory committees; ProNAi: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Chavez:Janssen: Speakers Bureau. Levy:Kite Pharma: Consultancy; Five Prime Therapeutics: Consultancy; Innate Pharma: Consultancy; Beigene: Consultancy; Corvus: Consultancy; Dynavax: Research Funding; Pharmacyclics: Research Funding. Reagan:Seattle Genetics: Research Funding. Bot:Kite Pharma: Employment, Equity Ownership. Rossi:Kite Pharma: Employment, Equity Ownership. Navale:Kite Pharma: Employment, Equity Ownership. Jiang:Kite Pharma: Employment, Equity Ownership. Aycock:Kite Pharma: Employment, Equity Ownership. Elias:Kite: Employment, Equity Ownership. Wiezorek:Kite Pharma: Employment, Equity Ownership. Go:Kite Pharma: Employment, Equity Ownership.

7503 Background: Prior to use of novel targeted agents for CLL, debate existed regarding the best chemoimmunotherapy regimen to build upon in patients (pts) with non-del(11q) disease. The role of lenalidomide (L) was also not defined. CALGB 10404 was a randomized phase 2 study addressing these questions. Methods: Pts with untreated CLL requiring therapy were randomized to treatment with fludarabine + rituximab (FR), FR + 6 monthly consolidative treatments of L (5 mg days 1-21/28 x 1 then 10 mg days 1-21/28 x 5) (FR+L), or FR + cyclophosphamide (FCR). Based on pretreatment central interphase cytogenetic screening, pts with del(11q22.3) in at least 20% of cells were excluded from the primary analysis, testing whether 2-year progression-free survival (PFS) rate was improved in non-del(11q) pts within each arm. A target accrual of 103 non-del(11q) pts per arm provided at least 84% power to detect an increase in 2-year PFS rate from 60% to 73%; the critical value was 69% using a single stage design and type I error rate of 4%. Results: A total of 342 non-del(11q) CLL pts were randomized to treatment with FR (n = 123), FR+L (n = 109), or FCR (n = 110). Baseline characteristics were similar across arms. Two-year PFS rates with exact 90% CIs were 64% (57-71%) (FR), 71% (63-78%) (FR+L), and 74% (66-80%) (FCR). Median PFS was significantly shorter with FR compared to FR+L (p = 0.03) and FCR (p < 0.01): 43 (95% CI: 33-50), 66 (95% CI: 45-not reached), and 78 (95% CI: 58-not reached) months respectively. Median overall survival (OS) has not been reached for any arm. OS at 1, 2, and 3 years was similar across arms, although there was a plateau in OS with no events beyond 41 months in the FR+L arm, different from FR/FCR where events continued to occur. The most common adverse events were cytopenias and infections. Conclusions: FR+L and FCR met the protocol defined primary endpoint. FR+L extended PFS relative to FR and a plateau in survival differentiated this arm from the FR/FCR arms. Future studies comparing FR+L to FCR or incorporating L into other novel treatment regimens are justified. Support: U10CA180821, U10CA180882, Celgene. Clinical trial information: NCT00602459.

Key PointsBrief lenalidomide consolidation after chemoimmunotherapy is acceptably tolerated and extends PFS and OS in CLL. FCR has superior efficacy compared with FR chemoimmunotherapy for CLL.