Abstract: BACKGROUND: Maintenance rituximab in MCL has improved survival and supports the exploration of maintenance with novel targeted agents. Ibrutinib is a BTK inhibitor approved for relapsed/refractory MCL. We report the final analysis of safety and efficacy of Ibrutinib maintenance (I-M) as monotherapy following chemo-immunotherapy induction for treatment-naive MCL in a multicenter phase II trial. METHODS: Pts with CR/PR to frontline chemo-immunotherapy (+/- autologous stem cell transplant (autoSCT)) received I-M 560 mg daily for up to 4 years. The primary endpoint was 3-year PFS rate. Secondary endpoints were to determine PR to CR conversions, median OS and the safety profile of I-M. Minimal residual disease (MRD) was measured using an NGS-MRD assay on peripheral blood (detection resolution of 1 cell per million; clonoSEQ®; Adaptive Biotechnologies) prior to and 1, 6 and 18-24 mo(s) after initiation of I-M. RESULTS: 36 pts were enrolled to complete accrual. Median age was 60 years (range 46-90). For induction, most pts were treated with BR (n=17, 47%) or a cytarabine-containing regimen (n=18, 50%). Eighteen (50%) pts underwent autoSCT. Thirty-four (94%) and 2 (6%) had CR and PR as best response to induction respectively, with 1 PR to CR conversion on I-M. At a median follow-up of 47 months, 10 (28%) pts completed a full I-M course, 7 (19%) remain on I-M, 15 (42%) discontinued I-M for treatment related adverse events (TRAEs) and 4 (11%) discontinued I-M for other reasons (PD x 1, secondary malignancies requiring treatment x 2, death cause unknown x 1). Three pts died during I-M, 2 deaths deemed unrelated to I-M (aspiration pneumonia, 2 nd malignancy) and 1 from unknown cause; 1 pt was lost to follow-up. Four pts were treated with rituximab maintenance after stopping I-M prematurely for toxicity without evidence of disease progression prior to or after change in therapy. At the time of data cut-off, MRD was assessed in 22 of 36 pts (available samples) at varying time points (Fig 1) with a dominant clone identified in all 22 pts. Pts were deemed MRD (-) if no sequences were detected at a threshold of & lt;10 -6 and (+) if sequences were detected at & gt;10 -6. Seventeen pts were MRD (-), 4 MRD indeterminate and 1 MRD (+) with radiographic CR after induction; the latter remained MRD (+) at 18 months with CR. All MRD indeterminate pts were MRD (-) when checked after 1 month on I-M. Six pts MRD (-) post-induction became MRD (+) during their I-M course. Of these pts, 2 reverted to MRD (-) with continued I-M; of the remaining 4 pts, 1 had PD and the others maintain stable clinical responses with ongoing I-M though MRD has not been rechecked. 3-year PFS and OS rates were 91% and 94% respectively (Figure 2A, B). PFS was improved in pts who received autoSCT prior to enrollment (Fig 2C, p=0.03) with a trend for improved OS (Figure 2D, p=0.057). MRD did not correlate with PFS (p=0.65) and OS (p=0.45) given few events. Atrial fibrillation/flutter occurred in 10 pts (28%; G1-2 n=7, 19%, G≥3 n = 3, 8%), 8 (22%) with new onset and 2 (6%) with worsening grade. HTN occurred in 20 pts (55%; G1-2 n=13, 33%, G≥3 n = 7, 22%), 15 (42%) with new onset and 5 (14%) with worsening grade. Incidences of both atrial fibrillation/flutter and HTN increased over time with ongoing I-M exposure (Table). Four pts had a 2 nd solid malignancy, 2 while on treatment and 2 after stopping I-M. TRAEs led to permanent dose reductions in 8 (22%) pts, 2 for neutropenia, 2 for fatigue, 2 for myalgias, 1 each for diarrhea and mucositis. Fifteen (42%) pts permanently discontinued I-M, most commonly for atrial fibrillation/flutter (n=8, 22%; n=5, 14% for G1-2). CONCLUSION: I-M 560 mg daily after response to frontline chemo-immunotherapy is feasible in MCL and results in durable PFS and OS. Toxicities including rates of high-grade atrial fibrillation/flutter and HTN are consistent with ibrutinib's known safety profile with increased incidence with longer exposure; discontinuation of I-M for atrial fibrillation/flutter in 22% of pts is higher than expected. Changes in NGS-MRD were noted in a small number of pts during maintenance. Extended follow-up and correlation of changes in MRD with PFS and OS are needed to determine clinical relevance of I-M and MRD status. Further studies evaluating maintenance with next generation BTK inhibitors as alternatives to ibrutinib should be explored to mitigate toxicity. Figure 1 Figure 1. Disclosures Karmali: Takeda: Research Funding; Genentech: Consultancy; Roche: Consultancy; Epizyme: Consultancy; Morphosys: Consultancy, Speakers Bureau; BeiGene: Consultancy, Speakers Bureau; Janssen/Pharmacyclics: Consultancy; BMS/Celgene/Juno: Consultancy, Research Funding; AstraZeneca: Speakers Bureau; Karyopharm: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding, Speakers Bureau; EUSA: Consultancy. Abramson: Seagen Inc.: Research Funding; Allogene Therapeutics: Consultancy; Astra-Zeneca: Consultancy; Incyte Corporation: Consultancy; BeiGene: Consultancy; Kymera: Consultancy; Bluebird Bio: Consultancy; Genmab: Consultancy; EMD Serono: Consultancy; Bristol-Myers Squibb Company: Consultancy, Research Funding; Novartis: Consultancy; Kite Pharma: Consultancy; Morphosys: Consultancy; C4 Therapeutics: Consultancy; AbbVie: Consultancy; Karyopharm: Consultancy; Genentech: Consultancy. Stephens: JUNO: Research Funding; Abbvie: Consultancy; Adaptive: Membership on an entity's Board of Directors or advisory committees; Beigene: Membership on an entity's Board of Directors or advisory committees; Innate Pharma: Membership on an entity's Board of Directors or advisory committees; Novartis: Research Funding; AstraZeneca: Consultancy; CSL Behring: Consultancy; Celgene: Consultancy; Mingsight: Research Funding; Arqule: Research Funding; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees; Epizyme: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees, Research Funding. Winter: Ariad/Takeda: Other: Husband: Data and Safety Monitoring Board; Actinium Pharma: Consultancy; BMS: Other: Husband: Data and Safety Monitoring Board; Gilead: Other: Husband: Consultancy; Janssen: Other: Husband: Consultancy; Epizyme: Other: Husband: Data and Safety Monitoring Board; Agios: Other: Husband: Consultancy; Novartis: Other: Husband: Consultancy, Data and Safety Monitoring Board; Merck: Consultancy, Honoraria, Research Funding; Karyopharm (Curio Science): Honoraria. Ma: Juno: Research Funding; Beigene: Research Funding, Speakers Bureau; AstraZeneca: Honoraria, Research Funding, Speakers Bureau; Loxo: Research Funding; Janssen: Research Funding, Speakers Bureau; Abbvie: Honoraria, Research Funding; TG Therapeutics: Research Funding; Pharmacyclics: Research Funding, Speakers Bureau. Petrich: Daiichi-Sankyo: Current Employment; Abbvie: Ended employment in the past 24 months. Hochberg: Leuko: Consultancy; Trapelo Health: Consultancy. Kuhr: Adaptive Biotechnologies: Current Employment. Lee: Adaptive Biotechnologies: Current Employment. Gordon: Zylem Biosciences: Patents & Royalties: Patents, No royalties; Bristol Myers Squibb: Honoraria, Research Funding. OffLabel Disclosure: We will report on the use of ibrutinib maintenance after front-line induction therapy in MCL.

Abstract: Introduction: Radioimmunotherapy is a targeted approach to cancer care. It has been shown to improve progression-free survival and quality of life in people with specific types of non-Hodgkin's lymphoma, including CD20- and CD37-positive B-cell lymphoma (Barr et al., 2018 NCT00770224; Green & Press, 2017; Kolstad et al., 2018 NCT01796171; Witzig et al., 2002). It has also been shown to increase the proportion of people who achieve complete response to therapy (Green & Press, 2017). Although CD20-targeted therapy has been approved in the US and Europe for nearly two decades, its use remains limited. At its peak in the UK in 2007, only 57 people with lymphoma were treated with the therapy (Rojas et al., 2019). However, research is ongoing; a PubMed search for 'radioimmunotherapy' and 'lymphoma' produces 1,097 articles in the past 20 years, including over 300 articles in the past ten years. With novel applications (CD37- and CD22-targeted) currently under investigation, it is increasingly important to understand potential system and policy barriers to uptake, such that existing roadblocks are overcome. Tackling these challenges is essential to ensuring that radioimmunotherapy is appropriately integrated into relevant clinical guidelines and care pathways. Aim: To better understand the policy and system barriers to integration of existing and novel radioimmunotherapy into lymphoma care in the US and the UK. Methodology: We conducted a structured literature review, taking a systems approach, to explore each of the five domains of the health system as outlined in the Radioligand Therapy Readiness Assessment Framework (Figure 1. Five core domains of the health system, with subdomains; The Health Policy Partnership, 2021). This approach allowed us to gain a holistic understanding of what integration of radioimmunotherapy involves and identify potential barriers, from clinical development through to patient care. We also conducted semi-structured interviews with lymphoma experts in the US (N=5) and UK (N=6), including clinicians and nurses ('clinical experts', N=8) and patient advocates ('advocates', N=3). Our work was guided by national expert advisory groups in each country. Results: While the US and UK health systems are organized and funded very differently, the literature and expert interviews revealed many common strategic challenges to the integration of radioimmunotherapy. These were: 1) low awareness and understanding of radioimmunotherapy among newly licensed healthcare professionals (an issue raised by n=8 clinical experts); 2) limited awareness by patient advocates, patients and policymakers (n=3 advocates); 3) caution around uptake of new radioimmunotherapy agents based on limited access to and use of older treatments (n=7 clinical experts); 4) nonexistent referral pathways and unclear models of working which discourage shared care and hinder multidisciplinary coordination (n=4 clinical experts); 5) lack of recent clinical data and research to support evidence-based use (n=5 clinical experts); 6) reimbursement concerns (n=5 clinical experts). Policy implications: Taking a systems approach to explore potential barriers to integration of radioimmunotherapy has allowed us to explore potential adaptations needed to achieve multisectoral and multidisciplinary working. Our findings reveal that professional societies, policymakers and patient advocacy groups will need to work together to overcome these barriers by: 1) reaching consensus on timing and eligibility criteria for use of radioimmunotherapy; 2) creating accurate and consistent patient-friendly information; 3) efficiently updating clinical training and treatment guidelines to include approved radioimmunotherapy; 4) developing evidence-based and personalized referral and treatment pathways which ensure consistency of care; and 5) investing in data collection and analysis to continually inform practice. Figure 1 Figure 1. Disclosures Morgan: Nordic Nanovector: Consultancy; Advanced Accelerator Applications: Consultancy. Merkel: Advanced Accelerator Applications: Consultancy; Amgen: Consultancy; AstraZeneca: Consultancy; Bayer: Consultancy; Bristol-Myers Squibb: Consultancy; Curium: Consultancy; Johnson & Johnson: Consultancy; MSD: Consultancy; Nordic Nanovector: Consultancy; Novartis: Consultancy. Gordon: Zylem Biosciences: Patents & Royalties: Patents, No royalties; Bristol Myers Squibb: Honoraria, Research Funding. Buscombe: Advanced Accelerator Applications Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Wait: Bayer: Consultancy; Curium: Consultancy; Johnson & Johnson: Consultancy; MSD: Consultancy; Advanced Accelerator Applications: Consultancy; Nordic Nanovector: Consultancy; Shionogi: Consultancy; Bristol-Myers Squibb: Consultancy; Amgen: Consultancy; AstraZeneca: Consultancy. Dreyling: Genmab: Consultancy; Celgene: Consultancy, Research Funding, Speakers Bureau; Amgen: Speakers Bureau; Astra Zeneca: Consultancy, Speakers Bureau; Bayer HealthCare Pharmaceuticals: Consultancy, Research Funding, Speakers Bureau; BeiGene: Consultancy; Gilead/Kite: Consultancy, Research Funding, Speakers Bureau; Incyte: Consultancy, Speakers Bureau; Janssen: Consultancy, Research Funding, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Roche: Consultancy, Research Funding, Speakers Bureau; Abbvie: Research Funding. Mittra: Advanced Accelerator Applications Novartis: Consultancy, Honoraria, Research Funding; Curium: Consultancy, Honoraria; Nordic Nanovector: Research Funding. Gopal: Janssen: Consultancy, Honoraria, Research Funding; Cellectar: Consultancy, Honoraria; Bristol Meyers Squibb: Research Funding; SeaGen: Consultancy, Honoraria, Research Funding; I-Mab bio: Consultancy, Honoraria, Research Funding; Incyte: Honoraria; MorphoSys: Honoraria; Servier: Consultancy, Honoraria; Genetech: Consultancy, Honoraria, Research Funding; IGM Biosciences: Research Funding; Astra-Zeneca: Research Funding; Karyopharm: Consultancy, Honoraria; Takeda: Research Funding; Teva: Research Funding; Agios: Research Funding; Kite: Consultancy, Honoraria; ADC Therapeutics: Consultancy, Honoraria; Acrotech: Consultancy, Honoraria; Merck: Consultancy, Honoraria, Research Funding; Epizyme: Consultancy, Honoraria; Nurix Inc: Consultancy, Honoraria; Beigene: Consultancy, Honoraria; Gilead: Consultancy, Honoraria, Research Funding.

Abstract: Background: Chromosome 9p24.1/PD-L1/PD-L2 genomic copy number alterations (CNAs) including amplifications and copy number gains (CNGs) are predominant features of classic Hodgkin lymphoma (cHL) and lead to overexpression of the programmed death-1 (PD-1) ligands 1 and 2 (PD-L1 and PD-L2). Amplifications and high level CNGs have been associated with advanced stage cHL and inferior treatment outcomes with standard chemotherapy. There are few studies that correlate 9p24.1/PD-L1/PD-L2 amplifications or CNGs with response to PD-1 blockade monotherapy in the frontline setting. We conducted a phase 2 clinical trial of sequential pembrolizumab (PEM) x 3 followed by doxorubicin, vinblastine, dacarbazine (AVD) chemotherapy (4-6 cycles) for newly diagnosed cHL. Interim response to single agent PEM was assessed by PET-CT and by decline in metabolic tumor volume (MTV). Herein, we report the results of correlative studies analyzing 9p24.1 CNAs, PD-1 pathway expression and response to PD-1 blockade. Methods: Pre-treatment diagnostic biopsy specimens were double stained for PD-L1 (E1L3N, XP Cell Signaling) and PAX5, single stained for PD-L2 and pSTAT3, and scored by two expert hematopathologists (QC, LBS) for percentage positive cells and intensity of staining. A modified H score was calculated as the product of staining intensity (0-3) and percentage of positive tumor cells (0-100%), ranging from 0 - 300. Fluorescence in situ hybridization to assess (FISH) chromosome 9p24.1 CNAs was performed by co-hybridizing PD-L1/PD-L2 probes (target) with the centromeric 9 probe (control). In each case, the percentage and magnitude of 9p24.1 CNAs were evaluated. Four FISH categories were defined based on the target: control ratio and the total copy numbers (CNs) of the target per Hodgkin Reed-Sternberg (HRS) cell to include: amplification (ratio≥3, CNs≥ 6), copy number gain (CNGs) (1≤ratio & lt;3, 2 & lt;CNs & lt;6), polysomy (ratio~1, CNs=3~5), and disomy (ratio=1, CNs=2). Patients were categorized according to the highest level of 9p24.1 alteration reaching at least 10% of counted cells. The relationships between PD-1 pathway markers, genomic alterations, and response to single agent PEM by MTV were assessed statistically using Fisher's Exact Test, Kruskal-Wallis test, and Spearman's Rank Correlation as appropriate. PD-L1 H Scores were grouped into terciles of approximately equal size for categorical analysis. Response was defined as a complete metabolic response (CMR), ≥ 90% reduction in MTV (near CMR), or partial response with & lt; 90% reduction by MTV (PR). Results: Thirty patients were enrolled from September 2017, through August 1, 2019; 28 had tissue available for FISH analysis and 29 for immunohistochemistry. Response to single agent PEM was PR in 11 (36.7%), near-CMR in 8 (26.7%), and CMR in 11 (36.7%). CMR rate following AVD x 2 was 100%. All patients in this analysis had genomic alterations, although 5 patients did not reach the cut off of 10%. The highest level alteration was amplification in 11 patients (36.7%), copy gain in 7 (23.3%), polysomy in 5 (16.7%) and disomy in 5 (16.7%) (Table 1). The average 9p24.1 copy number per HRS cell was 3.1 (range 2-8.1). Six of 22 examined cases were EBER-positive. There was no evidence of a statistical relationship between response to single agent PEM and 9p24.1 alteration, PD-L1, PD-L2 or STAT3 H-scores, or EBER status. We found PD-L1 H Score tercile differed statistically by FISH category (P=.024, Fisher's Exact Test). Notably, there were no patients with amplification in the lowest tercile. More compelling, we found a positive association between PD-L1 H Score and average 9p24.1 locus copy number (Spearman's ρ=.36, P=.063, Fig 1a) and a negative association between PD-L1 H Score and percent disomic cells (Spearman's ρ= -0.21, P=0.29, Fig 1b) although the statistical significance of these results was limited by the small sample size. Conclusions: Our data is consistent with prior reports indicating a positive association between 9p24.1 genetic alterations and PD-L1 expression. The high response rates observed at all PD ligand levels seen in this clinical study suggests that even low levels of PD ligand expression may be sufficient for response to PD-1 blockade in previously untreated cHL. Disclosures Allen: Bayer:Consultancy, Other;Imbrium:Consultancy, Other;Research to Practice:Speakers Bureau;Clinical Care Options:Speakers Bureau;Curio Sciences:Honoraria.Evens:Merck:Consultancy, Honoraria, Research Funding;Pharmacyclics:Consultancy, Honoraria;Novartis:Consultancy, Honoraria;MorphoSys:Consultancy, Honoraria;Research To Practice:Honoraria, Speakers Bureau;Abbvie:Consultancy, Honoraria;Mylteni:Consultancy, Honoraria;Seattle Genetics:Consultancy, Honoraria, Research Funding;Epizyme:Consultancy, Honoraria, Research Funding.Advani:Celgene, Forty Seven, Inc., Genentech/Roche, Janssen Pharmaceutical, Kura, Merck, Millenium, Pharmacyclics, Regeneron, Seattle Genetics:Research Funding;Astra Zeneca, Bayer Healthcare Pharmaceuticals, Cell Medica, Celgene, Genentech/Roche, Gilead, KitePharma, Kyowa, Portola Pharmaceuticals, Sanofi, Seattle Genetics, Takeda:Consultancy.Pro:Verastem Oncology:Research Funding.Karmali:Takeda:Research Funding;BeiGene:Speakers Bureau;BMS/Celgene/Juno:Honoraria, Other, Research Funding, Speakers Bureau;Karyopharm:Honoraria;AstraZeneca:Speakers Bureau;Gilead/Kite:Honoraria, Other, Research Funding, Speakers Bureau.Gordon:Zylem Biosciences:Patents & Royalties: Patents, No Royalties.Winter:Amgen:Consultancy;Epizyme:Other: DSMB;Norvartis:Consultancy, Other: DSMB;CVS/Caremark:Consultancy;Ariad/Takeda:Consultancy;Delta Fly Pharma:Consultancy;Merck:Membership on an entity's Board of Directors or advisory committees, Other: advisory board;Karyopharm:Membership on an entity's Board of Directors or advisory committees, Other: advisory board.

Abstract: Background: Mantle cell lymphoma (MCL) is a B-cell non-Hodgkin lymphoma (NHL) with a prevalence of approximately 15,000 cases in the United States. Although current therapeutics extend longevity, the median survival is 3 to 5 years warranting continued investigation for newer therapeutics. MCL is characterized by cells with enhanced proliferation combined with impaired apoptosis characteristic of indolent lymphomas. Therefore, therapeutic approaches targeting transcription, translation, or cellular bioenergetics may prove to be more effective than therapies targeting DNA replication. In addition, therapeutic strategies that exploit the altered cellular metabolism of tumor cells may be beneficial. Nucleoside analogues have been used extensively in the treatment of hematologic malignancies and are selective for tumor cells. Our laboratories have developed two purine nucleoside analogues i.e. 8-chloro-adenosine (currently in clinical trials) and a congener, 8-amino-adenosine (8-NH2-Ado), showing high efficacy for multiple myeloma, a slow growing plasma B-cell malignancy. Characterization of the mechanism of toxicity of 8-NH2-Ado in myeloma shows decreased RNA synthesis preceding decreased DNA synthesis, inactivation of Ser/Thr kinases, and reductions in intracellular ATP and glucose consumption. Based on this pleiotropic profile of cellular pathways involved in the execution of cell death by 8-NH2-Ado, we sought to determine its efficacy in MCL. Results: We determined toxicity of 8-NH2-Ado in a panel of MCL cell lines, including, JeKo-1, Mino and Granta 519. Viability was assessed by Annexin V/Dapi double staining after 24 hours of incubation with increasing concentrations of 8-NH2-Ado. All three cell lines demonstrated sensitivity to 8-NH2-Ado with JeKo-1 being the most sensitive (IC50 at 2 uM) followed by Mino and Granta 519. The induction of apoptosis correlated with cleavage of PARP and caspase activation and with decreases in cyclin D1 and Mcl-1 expression. JeKo-1 cells rapidly metabolized 8-NH2-Ado to 8-NH2-ATP. After 6 hrs of incubation, the 8-NH2-ATP intracellular concentration was more than 5 mM, and the ATP concentration was reduced by more than 50%. Additionally after 6 hrs of incubation, the rates of RNA and DNA synthesis were reduced by at least 60% based on [3H]uridine and [3H] thymidine incorporation assays. In an assessment of downstream signaling kinases, p38 and AKT were rapidly de-phosphorylated after 5 hrs of treatment. Because AKT controls cellular glucose consumption, we assessed effects on glucose consumption. In both the JeKo-1 and Granta 519 cells, we observed a similar reduction in glucose consumption; however, baseline glucose consumption in the less sensitive Granta 519 cells was higher. Conclusions: 8-NH2-Ado is highly toxic for the MCL cell lines tested. 8-NH2-Ado decreases Mcl-1 and cyclin D1 expression and decreases phosphorylation of AKT and p38 in both the JeKo-1 and Granta 519 cells. In the JeKo-1 cells, 8-NH2-Ado is metabolized to 8-NH2-ATP and decreases RNA/DNA synthesis and intracellular ATP. The early changes in cellular glucose consumption may facilitate 8-NH2-Ado induction of apoptosis. These pleiotropic features of 8-NH2-Ado in regulating cellular bioenergetics and induction of apoptosis may be particularly advantageous and warrant further investigation of 8-NH2- Ado for the treatment of MCL.

Abstract: Twenty-eight patients with relapsed or refractory CD20+ NHL have been enrolled in an ongoing phase I trial of dose-escalated 90YZ followed by high-dose BEAM and autotransplant in which the 90YZ dose is patient-specific based on dosimetry. 90YZ doses are calculated to deliver cohort-defined radiation doses (100, 300, 500, ... cGy) to critical organs (liver, lung or kidney), with 3–6 patients per group. On D -22, rituximab (R) 250 mg/m2 is infused followed by the imaging dose of 111In Zevalin® (5 mCi). Imaging is performed immediately post-injection and at 4, 24, 72, and 144 hours; dosimetry is performed on D -15. On D -14, R 250 mg/m2 is administered followed immediately by 90YZ at the dose calculated to deliver the cohort-prescribed absorbed radiation dose to the critical organ. On D -6 through -1, patients receive high-dose BEAM. On D0, a minimum of 2.0 X 106 CD34+ cells/kg is infused and G-CSF 5 μg/kg SQ daily begun. The median age was 54 (range: 25–72) years. NHL histologic subtypes were as follows: mantle cell 5, diffuse aggressive 13, low grade 5, and transformed 5. Most had received 3 or more treatment regimens, including R. The toxicity profile was similar to that associated with high-dose BEAM and included a decrease in DLCO for most patients with one patient at the 500 cGy dose level experiencing a transient decline to below 50% of the predicted value corrected for hemoglobin. The most common grade III/IV toxicities were infection, fever, stomatitis, nausea, vomiting, diarrhea, hemorrhage, and edema. One patient experienced transient veno-occlusive disease at the 700 cGy dose level. Engraftment occurred at a median of 10 days (range:8–18) to granulocytes ≥ 500/μL, and 21 days (range:13–40days) to platelets ≥20,000/μL . With a median follow-up of one year, the 3 year overall and progression-free survivals are 60% and 50%, respectively. Figure Figure 90-Y Zevalin Dosing by Cohort (median; range) Cohort (cGy) Total Dose (mCi) mCi/kg 100 (n=3) 5 (2–14) .06(.05–.12) 300 (n=7) 22(14–57) .25(.18–.63) 500 (n=6) 31(16–48) .40(.14–.63) 700 (n=6) 37(26–55) .38(.27–.73) 900 (n=3) 28(27–37) .32(.27–.44) 1100 (n=3) 48(29–65) .57(.50–.75) The liver was the critical organ in nearly all cases. Patient-specific doses calculated to deliver a cohort-prescribed absorbed radiation dose to the critical organ were highly variable suggesting that dosing based on weight and not dosimetry is likely to result in a wide range of absorbed dose to critical organs. In the context of this study, 90YZ has been administered to eight patients at doses of .5 mCi/kg or greater. We conclude that with careful dosimetry, 90YZ doses higher than the conventional .4 mCi/kg may be safely combined with BEAM and autotransplant. Accrual continues at the 1300 cGy dose level.

Abstract: Background: Autophagy represents a potential mechanism of cellular survival in settings of external stressors, such as starvation and exposure to cytotoxic drugs. Driven by the formation of autophagosomes, which digest nonessential cellular components during stress, autogphagy may be pharmacologically inhibited by 3-methyladenine (3-MA), an inhibitor of autophagosome formation. Histone deacetylase inhibitors (HDACI) block cancer cell proliferation by mechanisms that involve epigenetic gene regulation leading to cell growth arrest, differentiation, and apoptosis. Previous investigators have demonstrated synergistic cellular killing by a combination of HDACI and autophagy inhibitors in leukemia cell lines (Carew et al., Blood. 2007). Methods: We investigated whether a similar effect was possible in lymphoma. Specifically, we studied the combination of the pan-HDACI PCI-24781 and 3-MA in three lymphoma cell lines—Ramos (Burkitt’s lymphoma), Jeko, and Granta (both mantle cell lymphoma lines). Cells were cultured in RPMI (Invitrogen) and were incubated for 48 hours with 3-MA (1 mM and 2 mM), PCI-24781 (0.125 uM, 0.25 uM, 0.5 uM) and combinations of both agents. Apoptosis was determined by fluorescence-activated cell sorting (FACS) using AnnexinV-FITC/propidium iodide (AnnexinV+/PI+) staining. Western blots were performed to assess markers of apoptosis—beclin-1 and LC3B isoform I to II conversion. Results: In all three cell lines, treatment with PCI-24781 resulted in a dose-dependent increase in apoptosis. Our previous studies have shown that the IC70 (dose to achieve 70% AnnexinV+/PI+) was 1uM for PCI-24781 in the Ramos cell line. When 3-MA was combined with 0.25 uM PCI-24781, apoptosis increased from 13% to 35%. Similarly, 3-MA increased apoptosis from 8% to 18% and from 30% to 50% when added to PCI 24781 0.125 uM and 0.5 uM, respectively. Similar, albeit less striking, trends were seen in Jeko and Granta cells. Synergy was determined in Ramos cells by the combination index (CI) using isobolograms (CalcuSyn software). Moderate synergy was seen at PCI concentrations of 0.25 and 0.5 uM and a 3-MA concentration of 2 mM, with a CI of approximately 0.7. Immunoblots were analyzed for markers of autophagy—beclin-1 and LC3B isoforms I and II. Combined 3-MA and PCI-24781 reduced Beclin-1 expression as well as the conversion of LC3B isoform I to II in cells treated with the PCI-24781and 3-MA combination, as compared to cells treated with PCI-24781 alone, suggesting that inhibition of autophagy is responsible for the synergistic increase in apoptosis. This reduction was most prominent at 6 hours, indicating that autophagy inhibition is a relatively early event in this model. We conclude that inhibition of autophagy with 3-MA represents a novel approach to synergistically enhance cellular apoptosis induced by HDACI in lymphoma cells. Clinical studies taking advantage of this novel biology are warranted.

Abstract: Abstract 403 Background: Mantle Cell Lymphoma (MCL) is an uncommon histology of non-Hodgkin's lymphoma (NHL) with an unfavorable prognosis for which optimal initial therapy has not been clearly defined. Despite a number of single center studies and uncontrolled trials examining first-line therapy options in MCL, no randomized clinical trials or observational studies have directly compared initial therapeutic options in a single cohort of patients. The role of aggressive induction therapy versus sequential standard chemotherapy remains uncertain, particularly in younger patients. We therefore used the NCCN NHL Outcomes Database to compare R-HyperCVAD, R-CHOP followed by HDT/ASCR and R-CHOP alone as first-line therapy. Our endpoints were progression-free survival (PFS) and overall survival (OS). Methods: The NCCN Non-Hodgkin's Lymphoma Outcomes Database is a prospective cohort study collecting comprehensive clinical, treatment, and outcome data for patients seen at 7 participating NCCN centers. Overall, 229 patients 〈 65 years old with newly diagnosed MCL presented at NCCN institutions between August 2000 and February 2009. Patients were excluded if they (1) were enrolled in clinical trial (n=27), (2) did not receive Rituximab therapy (n=27), (3) did not receive either R-HyperCVAD or R-CHOP induction therapy (n=10), or (4) received both R-CHOP and R-HyperCVAD as induction (n=9). Induction therapy was determined as the initial chemo-immunotherapy received within 180 days of diagnosis. HDT/ASCR consolidation was defined as a transplant after achieving remission. In the R-CHOP+ HDT/ASCR group, ASCR was initiated within 100 days of induction therapy for 90% of patients. The maximum time from induction to ASCR was 172 days. In total, 156 patients were included in the final analysis. Median follow-up was 30 months. Results: Overall, 28 (18%) patients received R-CHOP alone, 29 (19%) received R-CHOP+HDT/ASCR, and 99 (63%) received R-HyperCVAD. No significant differences were observed between therapy groups with regards to co-morbidity (p=0.419), ECOG performance status (p=0.216), B symptoms (p=0.685), bulky disease (p=0.647), IPI risk group (p=0.247), or bone marrow involvement (p=0.651). No difference in PFS (p=0.546) was observed between the R-HyperCVAD and R-CHOP+HDT/ASCR arm (figure 1a). R-CHOP without consolidation had significantly poorer PFS than both R-HyperCVAD (p=0.001) and R-CHOP+HDT/ASCR (p=0.001). No significant differences in OS were observed between the three groups. However, there was a strong trend favoring R-HyperCVAD over R-CHOP (p=0.082, figure 1b). Conclusion: R-CHOP was inferior to both R-HyperCVAD and R-CHOP+HDT/ASCR, which had equal PFS and OS in patients with de novo mantle cell lymphoma. Even with these aggressive induction regimens in younger patient populations, the median PFS in these cohorts was only 3 years. Future trials should focus on incorporating novel agents rather than comparing efficacy of current suboptimal regimens. Disclosures: Czuczman: NCCN: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Nademanee:Genzyme Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Blayney:American Society of Clinical Oncology: Membership on an entity's Board of Directors or advisory committees; BlueCross Blue Shield of Michigan: Research Funding; NCCN: Honoraria; University of Michigan Health System: Employment. Friedberg:Genentech: Membership on an entity's Board of Directors or advisory committees.