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Tyrosine kinase inhibitors (TKIs) have improved the outcomes of patients with Philadelphia chromosome positive (Ph+) acute lymphoblastic leukemia (ALL). Many older patients (pts) are not good candidates for intensive chemotherapy and are treated with TKIs plus corticosteroids or low intensity chemotherapy. Although the remission rates with this approach have been high, the median disease-free survival (DFS) has been short. Therefore, novel treatment strategies are needed. This trial evaluated the feasibility of combining the TKI dasatinib with prednisone and blinatumomab in older pts with Ph+ ALL. Methods: This trial was activated through the NCTN in January 2015 and closed to accrual in April 2021. Pt eligibility included: age ≥ 65 years; Ph+ or Ph-like ALL (with dasatinib-sensitive fusions or mutations); newly diagnosed or relapsed/ refractory; no evidence of central nervous system (CNS) disease; and adequate organ function. Treatment: For induction, pts received dasatinib 140 mg/d orally (PO) Days 1-56 along with prednisone 60 mg/m 2/d PO Days 1-24. Pts achieving complete remission (CR) or CR with incomplete count recovery (CRi) (Day 28 or Day 56) continued dasatinib until Day 84 followed by 3 cycles of post-remission therapy (PRT) with blinatumomab/ dasatinib. Pts not achieving CR or CRi by Day 56 received re-induction with blinatumomab. Response was assessed at Day 35 of blinatumomab. Pts not achieving CR/ CRi could receive a second cycle of blinatumomab. This was followed by 3 cycles of PRT with blinatumomab/ dasatinib. Maintenance therapy consisted of prednisone 60 mg/m 2/d x 5 days every 28 days for a total of 18 cycles along with dasatinib 140 mg po qd indefinitely. CNS prophylaxis included intrathecal (IT) methotrexate every 4-6 weeks x 8 doses. IT methotrexate was given at least 2 days apart from blinatumomab. Response was assessed at Days 28, 56, 84 and additional time points were dependent on response. Minimal residual disease (MRD) was assessed centrally by multi-color flow cytometry at Day 28. Statistics: 9 eligible/ evaluable pts receiving PRT were to be evaluated before enrolling additional pts. Dose-limiting toxicities (DLTs) were defined as: > Grade 3 non-hematologic toxicities with the exception of nausea, vomiting, or diarrhea (if manageable with supportive care measures) or Grade 4 neutropenia lasting > 42 days with possible relationship to dasatinib or blinatumomab. If due to unexpected accrual, 12 pts were evaluable for DLT, the following rules would apply. If > 4 of the 12 pts experienced a DLT, the study would be temporarily closed pending review. Upon re-opening, 8 additional eligible and evaluable pts would be enrolled for a total of 20 pts receiving blinatumomab. Results: Due to rapid accrual, 16 pts enrolled before accrual was paused to assess feasibility and safety. Twelve pts were evaluable for DLT and 4 experienced a DLT: Grade 3 dyspnea and gastrointestinal pain (n=1), Grade 3 hypertension (n=1), Grade 3 dyspnea (n=1), Grade 3 hyperglycemia (n=1). These adverse events were deemed acceptable by the NCI and FDA and the study re-opened. A total of 25 eligible pts were accrued. The median age was 73 years (range 62-87). All pts were newly diagnosed. One pt was Ph-like, with the remainder being Ph+; 89% of Ph+ pts had additional cytogenetic abnormalities. During induction, 2 pts experienced treatment-related non-hematologic Grade 4 toxicities. No Grade 4 or higher treatment-related non-hematologic toxicities occurred during post-remission therapy or maintenance. Twenty-three out of 25 pts (92%) achieved a CR during dasatinib-based and prednisone induction therapy. Four did not receive PRT (2 due to adverse events, 1 to receive transplant, 1 because of insurance issues). Sixteen pts who achieved CR had MRD data. Five out of 16 pts (31%) were MRD negative at Day 28. One pt remains on PRT and 10 are on maintenance. The median follow up for pts who are alive is 1.7 years. The median overall survival (OS) and DFS have not been reached as of July 8, 2021. Kaplan-Meier 3-year estimates of OS and DFS are 85% (95% CI 58%-95%) and 80% (95% CI 55%-92%), respectively (Figure). Conclusions: This trial demonstrates the feasibility of combining dasatinib and blinatumomab in Ph+ ALL. In addition, with 1.7 years of follow up, outcomes are encouraging with high estimated 3-year DFS and OS. Longer follow up will be needed to determine the durability of these results. Figure 1 Figure 1. Disclosures Advani: Kite Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Research Funding; Glycomimetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Immunogen: Research Funding; OBI: Research Funding; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Honoraria, Research Funding; Macrogenics: Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding. Moseley: BioSight Ltd: Consultancy. Wood: Pfizer, Amgen, Seattle Genetics: Honoraria; Juno, Pfizer, Amgen, Seattle Genetics: Other: Laboratory Services Agreement. Park: Intellia: Consultancy; Kura Oncology: Consultancy; BMS: Consultancy; Affyimmune: Consultancy; Curocel: Consultancy; Novartis: Consultancy; Artiva: Consultancy; PrecisionBio: Consultancy; Servier: Consultancy; Kite Pharma: Consultancy; Innate Pharma: Consultancy; Minerva: Consultancy; Autolus: Consultancy; Amgen: Consultancy. Wieduwilt: Gilead: Membership on an entity's Board of Directors or advisory committees; Reata: Current holder of stock options in a privately-held company. Jeyakumar: Jazz: Research Funding; Pfizer: Research Funding. Atallah: Abbvie: Consultancy, Speakers Bureau; BMS: Honoraria, Speakers Bureau; Takeda: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Amgen: Consultancy. Gerds: PharmaEssentia Corporation: Consultancy; CTI BioPharma: Research Funding; Sierra Oncology: Consultancy; AbbVie: Consultancy; Celgene/Bristol Myers Squibb: Consultancy; Constellation: Consultancy; Novartis: Consultancy. O'Brien: Amgen, Astellas, Celgene, GlaxoSmithKline, Janssen Oncology, Aptose Biosciences Inc., Vaniam Group LLC, AbbVie, Alexion, Verastem, Juno Therapeutics, Vida Ventures, Autolus, Johnson and Johnson, Merck, Bristol Myers Squibb, NOVA Research Company, Eli Lill: Consultancy; Kite, Regeneron, Acerta, Caribou, Gilead, Pharmacyclics, TG Therapeutics, Pfizer, Sunesis: Research Funding. Othus: Celgene: Other: Data safety monitoring board; Merck: Consultancy; Biosight: Consultancy; Glycomimetics: Other: Data safety monitoring board; Daiichi Sankyo: Consultancy. Litzow: Jazz: Other: Advisory Board; Pluristem: Research Funding; Amgen: Research Funding; Actinium: Research Funding; Omeros: Other: Advisory Board; Astellas: Research Funding; AbbVie: Research Funding; Biosight: Other: Data monitoring committee. Stone: Actinium: Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy; Arog: Consultancy, Research Funding; Astellas: Membership on an entity's Board of Directors or advisory committees; BerGen Bio: Membership on an entity's Board of Directors or advisory committees; Boston Pharmaceuticals: Consultancy; Bristol Myers Squibb: Consultancy; Elevate Bio: Membership on an entity's Board of Directors or advisory committees; Foghorn Therapeutics: Consultancy; Gemoab: Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Consultancy; Innate: Consultancy; Janssen: Consultancy; Jazz: Consultancy; Novartis: Consultancy, Research Funding; Onconova: Consultancy; Syndax: Membership on an entity's Board of Directors or advisory committees; Syntrix/ACI: Membership on an entity's Board of Directors or advisory committees; Syros: Membership on an entity's Board of Directors or advisory committees; Aprea: Consultancy; Amgen: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy; Agios: Consultancy, Research Funding; Celgene: Consultancy; Macrogenics: Consultancy. Erba: AbbVie Inc; Agios Pharmaceuticals Inc; ALX Oncology; Amgen Inc; Daiichi Sankyo Inc; FORMA Therapeutics; Forty Seven Inc; Gilead Sciences Inc; GlycoMimetics Inc; ImmunoGen Inc; Jazz Pharmaceuticals Inc; MacroGenics Inc; Novartis; PTC Therapeutics: Research Funding; AbbVie Inc; Agios Pharmaceuticals Inc; Bristol Myers Squibb; Celgene, a Bristol Myers Squibb company; Incyte Corporation; Jazz Pharmaceuticals Inc; Novartis: Speakers Bureau; AbbVie Inc: Other: Independent review committee; AbbVie Inc; Agios Pharmaceuticals Inc; Astellas; Bristol Myers Squibb; Celgene, a Bristol Myers Squibb company; Daiichi Sankyo Inc; Genentech, a member of the Roche Group; GlycoMimetics Inc; Incyte Corporation; Jazz Pharmaceuticals Inc; Kura Oncology; Nov: Other: Advisory Committee.

Introduction: Lymphoma (LYM) diagnosed during pregnancy is an uncommon occurrence. There are significant ethical and management challenges that involve maternal and fetal risks associated with delayed intervention vs antenatal therapy. Moreover, there are a scarcity of available data regarding relapsed/refractory LYM occurring during pregnancy, which may guide practitioners and patients (pts) on treatment options, prognosis, maternal complications, and fetal outcomes. Methods: We performed a detailed retrospective analysis of pts diagnosed with relapsed LYM during pregnancy 1989-2021 across 10 academic centers worldwide. Data on disease characteristics, treatment, obstetric complications and fetal outcomes were examined. Survival analyses were performed using Kaplan-Meier. In addition, via an IRB approved protocol for a pt receiving antenatal checkpoint inhibitor therapy, we analyzed blood during gestation for measurement of nivolumab (NIVO) concentrations for comparison of pt serum concentrations to expected/predicted, as well as cord blood, and placenta concentrations for NIVO. All aliquots were run on a CLIA-level certified and validated ELISA assay (range 10-250 ng/mL, with dilutions up to 1000-fold [250 ug/mL]). Results: Overall, 23 cases of relapsed LYM during gestation were identified. 18 (78%) pts had Hodgkin LYM (HL), 2 (9%) peripheral T-cell LYM, and 1 pt each diffuse large B-cell LYM, follicular LYM, and marginal zone LYM. The median age of pts at time of relapse during pregnancy was 31 years (21-35). The median time from initial LYM diagnosis to pregnancy relapse was 24 months (7-229). Overall, 19 (82%) pts were White and there was 1 each Hispanic, Black, American Indian, and Asian. At time of relapse, 3 (13%) pts had stage I, 10 (44%) stage II, 4 (17%) stage III, and 4 (17%) stage IV disease; 12 (52%) pts presented with B-symptoms. Therapy was deferred to post-partum in the majority of pts; however, 5 (22%) pts received antenatal therapy (due to tumor burden, etc) between 20-32 weeks' gestation (Table). Among these, 4 achieved a complete response (CR), with 1 pt who had antenatal progressive disease (PD) requiring change to NIVO as detailed below. This 31-year-old female presented at 13 weeks' gestation with biopsy-proven relapsed HL (6 ABVD cycles 3 years prior). By 18 weeks, her ECOG PS was 3, and she developed bulky pelvic adenopathy >10cm, and severe hypercalcemia, hyponatremia, and progressive non-hemolytic anemia (5.4 gm/dL). Modified ESHAP was started at week 19 with brisk subjective improvement and resolution of lab abnormalities; however, she had PD at week 25. Single-agent NIVO was started after counseling about potential risks/benefits. She received 240 mg IV q 2 weeks for 6 cycles (through week 37) resulting in near CR, and she delivered a healthy full-term male at 38.2 weeks. A 30-day post-partum PET confirmed CR. In addition, maternal NIVO pharmacokinetic (PK) analyses showed levels were within normal ranges based on PK simulations (Figure 1). Cord blood concentration was 64% of the maternal exposure blood level, while there was no quantifiable NIVO detected in the placental tissue. Overall, 9 (39%) pts underwent transplantation post-partum (Table). With a median follow-up of 37 months for all pts, 3-year progression-free survival (PFS) and overall survival (OS) were 33% and 90%, respectively (Figure 2). Detailed maternal and fetal outcomes were available on 22 pts (Table). Of these, there were 18 lives births with the majority having vaginal delivery. The majority of pts had clinician-initiated late preterm deliveries with a median gestational age at delivery of 36 weeks (26-39). The median birthweight was 2777 grams (740-3900), and there were no reported malformations. For maternal complications, 1 pt each had preeclampsia, endometritis, and chorioamnionitis (all pts who deferred antenatal therapy). Conclusions: To the best of our knowledge, this is the largest cohort of pts diagnosed with relapsed LYM during pregnancy to date, including the first report of a LYM pt receiving antenatal checkpoint inhibitor immunotherapy. Treatment was deferred in the majority of pts, though it was well tolerated by those who received antenatal therapy. Furthermore, there were relatively few obstetrical or fetal complications. And despite modest PFS, OS was robust. Finally, use of antenatal NIVO in one relapsed HL pt was safe, effective, and associated with expectant maternal PKs. Figure 1 Figure 1. Disclosures Ahmed: Tessa Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Seagen: Research Funding; Merck: Research Funding; Xencor: Research Funding. Olszewski: TG Therapeutics: Research Funding; PrecisionBio: Research Funding; Celldex Therapeutics: Research Funding; Acrotech Pharma: Research Funding; Genentech, Inc.: Research Funding; Genmab: Research Funding. Hamad: Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Farooq: Kite, a Gilead Company: Honoraria. Vose: Kite, a Gilead Company: Honoraria, Research Funding. OffLabel Disclosure: nivolumab used in 2nd-3rd trimester of pregnancy for a woman w/ Hodgkins lymphoma

Introduction: Diffuse large B-cell lymphomas (DLBCL) transformed from indolent B-cell non-Hodgkin lymphomas (B-NHL) or Richter transformation (RT) from chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL) are associated with a poor prognosis, particularly in patients (pts) with relapsed/refractory (RR) disease. PD-1/PD-L1 blockade has produced anti-tumor responses in pts with lymphoma; however, the response rate in pts with DLBCL is low. Preclinical data suggest that some "immunogenic" chemotherapies alter the tumor microenvironment and act synergistically with checkpoint blockade to improve anti-tumor responses. We evaluated the addition of the PD-L1 inhibitor, atezolizumab, to immunogenic chemoimmunotherapy, rituximab with gemcitabine and oxaliplatin (R-GEMOX) in pts with RR transformed DLBCL. Methods: Pts with DLBCL transformed from indolent B-NHL or RT from CLL that had received ≥ 1 prior regimen with ECOG performance status ≤ 2, and adequate organ and hematologic function were eligible for this phase 1 study. Two cohorts were enrolled, one for pts with DLBCL transformed from follicular lymphoma (FL) and another for pts with non-FL transformed DLBCL, including RT. R-GEMOX was administered without atezolizumab on C1D1, R-GEMOX+Atezo was given subsequently (Days 1+15 of 28 day cycles) for a maximum of 6 doses. Pts in CR could proceed to R+atezo q3w maintenance for up to 2 years. Pts could proceed to hematopoietic cell transplantation (HCT) without subsequent maintenance at the discretion of the treating MD. A safety lead-in (6 pts, any cohort) with dose-limiting toxicity (DLT) evaluation (28-day period, after 1 st dose of atezo) at dose level (DL) 1 (rituximab 375mg/m2, gemcitabine 1000mg/m2, oxaliplatin 100mg/m2, atezolizumab 840mg, with de-escalation dose level available) was enrolled to confirm the recommended phase 2 dose (RP2D). After confirmation of the RP2D, expansion will continue until enrollment of n=14 transformed FL and n=10 non-FL transformed DLBCL. Responses were assessed by investigators by PET-CT (after C2, C4, and then q12weeks) according to the 2014 Lugano Classification. The primary endpoint was safety and determination of the RP2D. Results: 23 pts were enrolled, 22 were evaluable for response and adverse events (AEs), 1 is too early. Baseline characteristics are summarized in Table 1. 1/6 pts had a DLT related to atezolizumab during safety lead-in: grade (G) 4 Stevens-Johnson syndrome leading to death. DL1 was the RP2D. 2 pts were replaced during safety lead-in due to progressive disease (PD) prior to completing DLT evaluation. The most common AEs with R-GEMOX+Atezo (n=22) were fatigue (50%), elevated transaminases (45%), thrombocytopenia (45%), nausea/vomiting (41%), diarrhea (32%), fever (32%), hypertension (HTN) (27%), and neutropenia (27%). Common G3-4 AEs included lymphopenia (n=4), neutropenia (n=4), HTN (n=3), leukopenia (n=3), thrombocytopenia (n=3). Among 7 pts who proceeded to maintenance R-atezo, the most common AEs were fatigue (n=4) and HTN (n=3). There were 2 deaths related to study therapy, the pt with SJS and 1 pt with infusion reaction leading to respiratory failure who also had PD with both factors likely contributing to death. In addition, 1 pt had both sepsis and PD and died during maintenance, considered possibly related to treatment. 7 deaths were unrelated to treatment, including 1 from complications after autologous HCT, and 6 after PD. 5 pts remain on treatment; 17 pts are off treatment. Reasons for study discontinuation include: insufficient response/PD (n=12), HCT (n=2), death due to toxicity (n=2), and G3 neuropathy during maintenance (n=1). Among the 22 pts, the ORR was 50% and CR rate was 29%. The 9 pts with transformed FL had an ORR of 67% and CR rate of 33%. The 13 pts with non-FL transformed DLBCL/RT had an ORR of 38% and CR rate of 23%. Of 9 pts with RT there was 1 CR and 1 PR while all 3 pts with transformed marginal zone lymphoma responded (2 CR, 1 PR). Among responders (n=11), the median duration of response was not reached (Figure 1). Of the 6 pts with CR, 2 proceeded to HCT, and 4 had ongoing CR lasting 30.7+ months (mo), 13.9+ mo, 6.8+ mo, 5.0+ mo. Of the 5 patients with PR, 1 pt died of SJS without PD, PR lasted 3 and 4 mo in 2 patients (PD), and 2 pts have ongoing response (0.5+ and 2.0+ mo). Conclusions: R-GemOx+Atezo was tolerable and produced objective responses in patients with transformed DLBCL/RT, with all pts in CR having ongoing response. Figure 1 Figure 1. Disclosures Herrera: Gilead Sciences: Research Funding; ADC Therapeutics: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; Tubulis: Consultancy; Takeda: Consultancy; Merck: Consultancy, Research Funding; Bristol Myers Squibb: Consultancy, Research Funding; Kite, a Gilead Company: Research Funding; AstraZeneca: Consultancy, Research Funding; Karyopharm: Consultancy; Seagen: Consultancy, Research Funding. Allen: Epizyme: Consultancy; Kyowa Kirin: Consultancy; Secure Bio: Consultancy; ADC Therapeutics: Consultancy; MorphoSys: Consultancy. Popplewell: Hoffman La Roche: Other: Food; Novartis: Other: Travel; Pfizer: Other: Travel. Shouse: Beigene: Honoraria; Kite Pharma: Speakers Bureau. Siddiqi: AstraZeneca: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Oncternal: Research Funding; BeiGene: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Juno Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Kite Pharma: 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; Janssen: Speakers Bureau; TG Therapeutics: Research Funding. Danilov: Gilead Sciences: Research Funding; Pharmacyclics: Consultancy, Honoraria; Beigene: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; TG Therapeutics: Consultancy, Research Funding; Takeda Oncology: Research Funding; Genentech: Consultancy, Honoraria, Research Funding; SecuraBio: Research Funding; Bayer Oncology: Consultancy, Honoraria, Research Funding; Astra Zeneca: Consultancy, Honoraria, Research Funding; Bristol-Meyers-Squibb: Honoraria, Research Funding; Rigel Pharm: Honoraria. Tuscano: Seattle Genetics: Research Funding; Bristol Myers Squibb: Research Funding; Takeda: Research Funding; Acrotech: Research Funding; Genentech: Research Funding; Pharmacyclics: Research Funding; Abbvie: Research Funding. OffLabel Disclosure: Atezolizumab is not approved for the treatment of aggressive B-cell non-Hodgkin lymphoma

Background: CML is managed by life-long TKI therapy in most pts which can be associated with chronic toxicities and substantial costs. Discontinuation of TKI in some pts can result in sustained therapy-free remission (TFR); however only a minority are candidates for discontinuation approaches; of those most still relapse and must restart TKI. High expression of programmed death receptor-1 (PD-1) and its ligand PD-L1 on CML-specific cytotoxic T-cells and CML cells, respectively, suggests that PD-1/PD-L1-mediated immune escape contribute to CML persistence and relapse after TKI discontinuation. We designed the BLAST MRD CML trial (NCT#03516279) to study whether adding anti-PD-1 antibody pembrolizumab to TKI therapy is safe and tolerable and increases rate of conversion to undetectable minimal residual disease (UMRD). We present data from the early safety cohort from this ongoing trial with a data cut-off date June 15th, 2021. Methods: BLAST MRD CML-1 is an ongoing national, ECOG-sponsored, single-arm pilot phase II clinical trial that enrolls adults with chronic phase CML who achieved a major molecular response (MR 3) but not UMRD while on a stable dose of up to three lines of TKI therapy. UMRD was defined as an undetectable BCR-ABL by central RQ-PCR (assay sensitivity of 4.5 [MR 4.5]) on 2 consecutive samples separated by ≥4 weeks. Once enrolled, pts continue on TKI and concurrently receive pembrolizumab 200mg IV on day (D)1 of each 21-D cycle with central MRD assessment every 4 cycles for 17 cycles. Pts who achieve UMRD at or prior to C17 discontinue pembrolizumab, while those with persistent MRD continue TKI + pembrolizumab for another 18 cycles. TKI is discontinued one year following first documentation of UMRD. After TKI discontinuation, BCR-ABL is monitored at defined intervals for 24 months. Primary endpoint is proportion of CML pts on stable-dose TKI who convert to UMRD within 2 years (yrs) of combined TKI + pembrolizumab therapy. Secondary endpoints include rates of TKI discontinuation and proportion of pts achieving 2-year TFR, MRD kinetics, and safety. Immune related and other adverse events (AE) were assessed and graded according to CTCAE v 5.0. Results: As of cut-off date, 6 pts enrolled in safety cohort. Median age was 43 yrs (range 32-65). TKIs received on trial included imatinib (N=2), dasatinib (N=3), and nilotinib (N=1). All 6 pts were on 2 nd line TKI. Median exposure to pembrolizumab was 20 doses (range, 5-36). Five pts were still on combined pembrolizumab + TKI treatment, while the 6 th pt has completed combined therapy for 2 yrs and then continued TKI monotherapy on trial after achievement of UMRD (pt has to be in UMRD for 1 yr before TKI can be discontinued). The combination of TKI and pembrolizumab was safe and well tolerated (Table 1). Only 3 pts experienced grade (G) 1/2 AEs as the worst non-hematologic AE while on trial. Hematologic toxicity reported was also generally minimal with only one G 1/2 anemia AE. The only reported G3 AE was a lipase elevation (283 U/L, normal range 11 - 55 U/L) noted on routine laboratory assessment in a pt receiving nilotinib at 400mg BID dose after 48 weeks of starting on trial combined therapy. Amylase was also elevated at G2. No baseline lipase levels were available as protocol at that time did not require baseline assessments. The pt had no symptoms and CT imaging showed no radiologic evidence of pancreatitis. The lipase and amylase levels normalized with holding of both nilotinib and pembrolizumab for 7 weeks, and the AE did not recur with resumption of combined therapy at same dose of pembrolizumab but with nilotinib reduced to 400mg daily. No G4 or 5 AEs occurred. No other dose-adjustments or treatment discontinuation/interruptions due to AEs occurred. No immune-related AEs (IRAEs) have been reported. Discussion: Data from the early safety cohort suggest that the combination of TKI and pembrolizumab is safe and well tolerated. The AEs observed were mild and generally G1/2. No pt discontinued trial therapy due to AEs. Only one G3 AE (asymptomatic lipase elevation) was reported, which could have been related to nilotinib therapy and could have predated trial entry as no baseline lipase value was available and was fully reversible with a temporary hold of therapy. No IRAEs have been reported to date. Work is ongoing on an amendment to study protocol to enhance accrual. Efficacy results will be reported as they mature. Figure 1 Figure 1. Disclosures Zeidan: Boehringer Ingelheim: Consultancy, Research Funding; Ionis: Consultancy; Gilead: Consultancy, Other: Clinical Trial Committees; Loxo Oncology: Consultancy, Other: Clinical Trial Committees; Daiichi Sankyo: Consultancy; Incyte: Consultancy, Research Funding; Astex: Research Funding; Jasper: Consultancy; Cardiff Oncology: Consultancy, Other: Travel support, Research Funding; Aprea: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; BeyondSpring: Consultancy; BMS: Consultancy, Other: Clinical Trial Committees, Research Funding; Acceleron: Consultancy, Research Funding; Novartis: Consultancy, Other: Clinical Trial Committees, Travel support, Research Funding; Genentech: Consultancy; Epizyme: Consultancy; AstraZeneca: Consultancy; BioCryst: Other: Clinical Trial Committees; Janssen: Consultancy; Kura: Consultancy, Other: Clinical Trial Committees; Geron: Other: Clinical Trial Committees; Astellas: Consultancy; ADC Therapeutics: Research Funding; Agios: Consultancy; Jazz: Consultancy; Pfizer: Other: Travel support, Research Funding; AbbVie: Consultancy, Other: Clinical Trial Committees, Research Funding. Radich: Amgen: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Genentech: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees. Bhatt: National Marrow Donor Program: Research Funding; Tolero Pharmaceuticals, Inc: Research Funding; Pfizer: Research Funding; Incyte: Consultancy, Research Funding; Jazz: Research Funding; Abbvie: Consultancy, Research Funding; Partnership for health analytic research, LLC: Consultancy; Servier Pharmaceuticals LLC: Consultancy; Rigel: Consultancy; Abbvie: Consultancy, Research Funding; Genentech: Consultancy. Luger: Syros: Honoraria; Agios: Honoraria; Daiichi Sankyo: Honoraria; Jazz Pharmaceuticals: Honoraria; Brystol Myers Squibb: Honoraria; Acceleron: Honoraria; Astellas: Honoraria; Pfizer: Honoraria; Onconova: Research Funding; Celgene: Research Funding; Biosight: Research Funding; Hoffman LaRoche: Research Funding; Kura: Research Funding. Litzow: Omeros: Other: Advisory Board; Astellas: Research Funding; Jazz: Other: Advisory Board; Amgen: Research Funding; Pluristem: Research Funding; Biosight: Other: Data monitoring committee; Actinium: Research Funding; AbbVie: Research Funding. OffLabel Disclosure: Pembrolizumab has not been approved for the treatment of CML

Study Background: Survival outcomes of older patients with AML are dismal with a 3-year survival of < 10%. The combination of hypomethylating agents (HMA) with venetoclax has emerged as the new standard of care for older unfit patients with AML, but median survival remains less than 15 months. Patients with undetectable MRD after this regimen seem to have the best long-term clinical outcomes. In this randomized phase 2 trial, the goal with combining pembrolizumab is to facilitate a more effective CTL mediated destruction of leukemic blasts resulting in improved rates of CR without MRD, which would hopefully increase duration of response and lower relapse rates. Here we report on the design of the first randomized multi-center clinical trial of HMA+venetoclax +/- ICPI in unfit AML patients. Methods: The primary objective of this Cancer Therapy Evaluation Program-approved multi-institutional, randomized phase II study (NCT04284787) is to assess the percentage of patients with MRD negative CR (MRD- CR) as measured by flow cytometry with chemotherapy + pembrolizumab during the first 6 cycles and compare between the two study arms (See study Schema). Secondary objectives include rates of CR / complete remission with incomplete count recovery (CRi), complete remission with partial recovery count (CRh) and Hematologic improvement (HI) to red blood cells and platelets, MRD negativity at Day 14, MRD-negative CR at end of induction therapy and MRD negative CR after last consolidation cycle, event free survival (EFS), relapse free survival (RFS), duration of response (DOR), and overall survival (OS), and proportion of patients who develop severe toxicity. Important exploratory objectives include MRD assessment by duplex sequencing (DS), and comparing DS and multiparameter flow cytometry for MRD detection. A total of 76 patients will be included (38 patients in the intervention arm and 38 patients in the control arm). Planned stratification factors include 1) cytogenetics (intermediate/unknown vs. adverse karyotype) 2) antecedent hematologic disorder defined as prior MDS, MPN, or aplastic anemia (present vs. absent); and 3) reason to not receive intensive chemotherapy (ineligibility vs refusal). All patients will receive azacitidine at 75 mg/m2 IV over 10-40 minutes or SQ x 7 days on Days 1-7 or Days 5-2 (to avoid weekend administration) and, including a ramp-up phase to 400 mg /day venetoclax on Days 1-4. Venetoclax will be administered at 400 mg/day on the remaining days of the cycle for the first cycle and on Days 1-21 or 1-28 for subsequent cycles (depending on count recovery). Half of the patients will receive pembrolizumab intravenously starting on Day 8 of the first cycle and then q 3 weeks in cycles 2-6 (intervention arm), up to 2 years of maintenance. The other half will not receive pembrolizumab (control arm). After 15 efficacy-evaluable patients in each of the two study arms have had their primary endpoint results available, a formal futility and toxicity analysis will be conducted. Follow up will continue up to 2 years after the last patient is randomized Eligible patients are aged ≥60 years with newly diagnosed and pathologically-confirmed AML, including secondary AML arising from prior MDS and therapy-related AML, who are deemed ineligible for intensive chemotherapy according to treating physician's assessment or who refuse intensive chemotherapy. Candidates with high risk MDS and secondary AML arising from myeloproliferative neoplasm or other hematologic disorders are not allowed. Additional exclusion criteria include CBF-AML, prior allogeneic stem cell transplant, receipt of prior hypomethylating therapy for antecedent MDS, active infection requiring systemic therapy, and use of corticosteroids. Responses in AML patients will be assessed using European Leukemia Net 2017 response criteria. EFS will be calculated as the time from initial treatment to either disease relapse or death. OS will be calculated from time from initial treatment to death. Biomarker analyses will include an extensive array of immunologic and correlative studies that will evaluate PD-1 and PD-L1 expression, immune cell subset analysis, leukemia specific T-cell response, cytokine level, T-cell receptor (TCR) repertoire, as well as RNA-seq, gut microbiome characterization and metabolomics, and whole exome sequencing for tumor and germline DNA. Disclosures Zeidan: Abbvie: Consultancy, Honoraria, Research Funding; MedImmune/Astrazeneca: Research Funding; Incyte: Consultancy, Honoraria, Research Funding; Jazz: Consultancy, Honoraria; Celgene / BMS: Consultancy, Honoraria, Research Funding; Trovagene: Consultancy, Honoraria, Research Funding; Agios: Consultancy, Honoraria; Boehringer-Ingelheim: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Acceleron: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; BeyondSpring: Consultancy, Honoraria; Cardiff Oncology: Consultancy, Honoraria, Other; Takeda: Consultancy, Honoraria, Research Funding; Ionis: Consultancy, Honoraria; Epizyme: Consultancy, Honoraria; Leukemia and Lymphoma Society: Other; CCITLA: Other; Astex: Research Funding; Aprea: Research Funding; ADC Therapeutics: Research Funding; Taiho: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; Daiichi Sankyo: Consultancy, Honoraria; Cardinal Health: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria, Research Funding; Otsuka: Consultancy, Honoraria. Radich:Amgen: Consultancy; Bristol-Myers Squibb: Consultancy; Jazz: Consultancy; Novartis Pharmaceuticals Corporation: Consultancy, Research Funding.

Study Background: The presence of minimal residual disease (MRD) after IC in AML patients is often a harbinger of relapse, and therapeutic targeting of MRD has emerged as an important strategy to improve long-term outcomes. The importance of the PD-1/PD-L1 pathway in immune evasion of AML has been demonstrated in murine AML models whereby PD-L1 and PD-1 were upregulated in leukemia cells, and PD-1 blockade suppresses invivo leukemia cell proliferation and improved survival in AML bearing mice (Zhang et al., 2009; Zhou et al., 2010). Combining IC with immune checkpoint inhibition (ICPI) has resulted in a significant clinical activity in some advanced solid malignancies including non-small-cell lung cancer. A recent single-arm phase 2 study combining IC with nivolumab showed the combination was feasible and resulted in undetectable MRD in 53% of patients with Complete response (CR)/CR with incomplete count recovery (CRi) (Ravandi et al, 2019). Here we report on the design of the first randomized multi-center clinical trial of IC+ICPI in fit AML patients. Methods: The primary objective of this investigator-initiated Cancer Therapy Evaluation Program (CTEP)-sponsored multi-institutional, randomized phase II study (NCT04214249) is to assess the percentage of patients with MRD negative CR (MRD- CR) as measured by flow cytometry at the end of first cycle of consolidation therapy with IC+ pembrolizumab and compare between the two study arms (Figure 1). Secondary objectives include rates of CR/CRi, complete remission with partial recovery count (CRh) and hematologic improvement (HI) to red blood cells and platelets, MRD negativity at Day 14, MRD-negative CR at end of induction therapy and MRD negative CR after last consolidation cycle, event free survival (EFS), relapse free survival (RFS), duration of response (DOR), and overall survival (OS), and proportion of patients who develop severe toxicity. Important exploratory objectives include MRD assessment by duplex sequencing (DS) and comparing DS and multiparameter flow cytometry for MRD detection. The study will consist of an induction, consolidation, and maintenance phase of therapy. A total of 124 patients will be included (62 patients in the intervention arm and 62 patients in the control arm). Planned stratification factors include 1) age (younger than 65 vs. 65 and older), 2) cytogenetics by FISH or metaphase karyotype (presence vs. absence of core binding factor inversions and translocations), and 3) t-AML or AML arising from prior/antecedent MDS. All patients will receive cytarabine at 100 mg/m2/day continuous infusion on Days 1-7 and either idarubicin 12 mg/m2/day IV on Days 1-3 or daunorubicin 60 mg/m2/day IV on Days 1-3. on Day 8 of the induction chemotherapy, half of the patients will receive pembrolizumab IV (intervention arm), and continue Q3 weeks throughout Induction/Consolidation, and thereafter for up to 2 years from the start of maintenance. The other half will not receive pembrolizumab (control arm). After 31 efficacy-evaluable patients (patients who had a bone marrow biopsy done after the first consolidation cycle) in each of the two study arms have had their primary endpoint results available, a formal futility and toxicity analysis will be conducted. Follow up will continue up to 2 years after the last patient is randomized. Eligible patients are aged ≥18 and ≤75 years with newly diagnosed and pathologically-confirmed AML, including secondary AML arising from prior MDS and therapy-related AML. Patients with FLT3-mutated AML are excluded as well as those with prior allogeneic stem cell transplant, active infection requiring systemic therapy, and requiring use of high dose corticosteroids. Responses in AML patients will be assessed using European Leukemia Net 2017 response criteria. EFS will be calculated as the time from initial treatment to either disease relapse or death. OS will be calculated from time from initial treatment to death. Biomarker analyses will include an extensive array of immunologic and correlative studies that will evaluate PD-1 and PD-L1 expression, immune cell subset analysis, leukemia specific T-cell response, cytokine level, T-cell receptor (TCR) repertoire, as well as RNA-seq, gut microbiome characterization and metabolomics, and whole exome sequencing for tumor and germline DNA. Figure 1 Disclosures Zeidan: Epizyme: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; Daiichi Sankyo: Consultancy, Honoraria; Cardinal Health: Consultancy, Honoraria; Acceleron: Consultancy, Honoraria; Leukemia and Lymphoma Society: Other; Jazz: Consultancy, Honoraria; Celgene / BMS: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Research Funding; Otsuka: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria; BeyondSpring: Consultancy, Honoraria; Cardiff Oncology: Consultancy, Honoraria, Other; Takeda: Consultancy, Honoraria, Research Funding; Ionis: Consultancy, Honoraria; MedImmune/Astrazeneca: Research Funding; Trovagene: Consultancy, Honoraria, Research Funding; Aprea: Research Funding; ADC Therapeutics: Research Funding; Astex: Research Funding; Incyte: Consultancy, Honoraria, Research Funding; Taiho: Consultancy, Honoraria; CCITLA: Other; Novartis: Consultancy, Honoraria, Research Funding; Boehringer-Ingelheim: Consultancy, Honoraria, Research Funding; Agios: Consultancy, Honoraria. Radich:Amgen: Consultancy; Bristol-Myers Squibb: Consultancy; Jazz: Consultancy; Novartis Pharmaceuticals Corporation: Consultancy, Research Funding.

Background: Chronic myeloid leukemia (CML) is driven by the activity of the oncogenic BCR-ABL tyrosine kinase, which can be effectively inhibited by tyrosine kinase inhibitors (TKIs) leading to prolonged overall and disease-free survival. Despite their effectiveness, disease can progress on TKI therapy, and lifelong treatment with TKI can have substantial negative effects on quality of life and financial health. Studies assessing the safety of TKI discontinuation in CML patients in molecular remission showed that TKIs can be discontinued in up to 45% of patients without disease recurrence. Programmed death receptor-1 (PD-1) is an inhibitory immune checkpoint receptor expressed by T-cells that can be inhibited by the anti-PD-1 monoclonal antibody pembrolizumab. Preclinical data have shown that PD-1 is highly expressed on CML-specific cytotoxic T-cells and PD-1 ligand (PD-L1) is present on CML cells. In murine CML models, the administration of anti-PD-L1 antibodies prolonged survival. As these studies suggest that disease relapse might be due to PD-1/PD-L1 mediated immune escape by CML cells, we designed the BLAST MRD CML 1 trial to study whether adding pembrolizumab to TKI is safe, increases the rate of conversion to undetectable minimal residual disease (UMRD) and allows a higher rate of TKI discontinuation. Methods: The primary endpoint of this ongoing national, ECOG-sponsored, single-arm pilot phase II clinical trial is to assess the proportion of CML patients on stable-dose TKI who convert to UMRD during or within 2 years of initiating pembrolizumab therapy (NCT#03516279). Secondary endpoints are (I) the proportion of CML patients who maintain UMRD for 6 months and 12 months, (II) the proportion of CML patients who discontinue TKI after achieving UMRD, (III) the proportion of patients who maintain UMRD off TKI at 2 years after first determined UMRD, and (IV) the incidence of grade 3 or 4 immune related adverse events related to pembrolizumab treatment during the first 2 years after registration. UMRD state is defined as an undetectable BCR-ABL using the central RQ-PCR assay with a sensitivity of 4.5 [MR4.5] on 2 consecutive occasions separated by at least 4 weeks with the date of achievement of UMRD constituting the date of first test. Immune related and other adverse events will be assessed according to CTCAE v 5.0 terminology and grading. Adult (≥18 years) patients with pathologically-confirmed CML and who have achieved major molecular response (MR3) but not UMRD at time of screening are eligible. Eligibility was recently expanded to allow third line TKI. Therefore, currently eligible patients must have been on first, second, or third line TKI therapy with either dasatinib, imatinib, nilotinib, or bosutinib for at least 2 years prior to enrolment. Patients with accelerated or blast phase CML or who have received prior allogeneic hematopoietic stem cell transplant or anti-PD-1/PD-L1 therapy are excluded. Patients will continue a standard dose of TKI therapy and receive pembrolizumab at 200 mg IV every 21 days (Figure 1). MRD status will be assessed centrally every 4 cycles. Patients who achieve UMRD at or prior to cycle 17 will discontinue TKI and pembrolizumab. If MRD remains positive prior to cycle 17, TKI and pembrolizumab will be continued for an additional 18 cycles. If MRD is still detectable after the second year of combined therapy, patients will come off study. If patients are in an UMRD state by the end of year 1 or 2 of pembrolizumab therapy, pembrolizumab will be discontinued. Patients who remain in UMRD status for one year after the first UMRD result will discontinue TKI therapy. Once TKI is discontinued, BCR-ABL will monitored q4 weeks for the first six months post TKI discontinuation, then q8 weeks for the subsequent six months, then q12 weeks for another year. Assuming that the addition of pembrolizumab to TKI will increase the conversion rate to UMRD from 20% to 40%, enrollment of 36 patients (40 patients to allow for 10% drop-out) would give this trial 91% power with a one-sided type-I error of 0.089. The combination therapy will be considered promising if 11 or more patients meet the criteria for TKI discontinuation. Toxicity will be monitored and reviewed every six months. Disclosures Zeidan: Incyte: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Cardinal Health: Consultancy, Honoraria; Leukemia and Lymphoma Society: Other; Epizyme: Consultancy, Honoraria; Ionis: Consultancy, Honoraria; Jazz: Consultancy, Honoraria; Celgene / BMS: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Otsuka: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria, Research Funding; Agios: Consultancy, Honoraria; Boehringer-Ingelheim: Consultancy, Honoraria, Research Funding; Cardiff Oncology: Consultancy, Honoraria, Other; Taiho: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Astellas: Consultancy, Honoraria; Daiichi Sankyo: Consultancy, Honoraria; Acceleron: Consultancy, Honoraria; CCITLA: Other; Astex: Research Funding; MedImmune/Astrazeneca: Research Funding; Trovagene: Consultancy, Honoraria, Research Funding; Aprea: Research Funding; Seattle Genetics: Consultancy, Honoraria; BeyondSpring: Consultancy, Honoraria; ADC Therapeutics: Research Funding. Radich:Amgen: Consultancy; Bristol-Myers Squibb: Consultancy; Jazz: Consultancy; Novartis Pharmaceuticals Corporation: Consultancy, Research Funding. Bhatt:Incyte: Consultancy, Research Funding; Takeda: Consultancy; Omeros: Consultancy; Agios: Consultancy; Rigel: Consultancy; Tolero: Research Funding; Abbvie: Consultancy, Research Funding; Pfizer: Research Funding; Partnership for health analytic research: Consultancy; Jazz: Research Funding; National Marrow Donor Program: Research Funding; Oncoceutics: Other. Gore:Abbvie: Consultancy, Honoraria, Research Funding. Luger:Daiichi-Sankyo: Honoraria; Pfizer: Honoraria; Bristol-Myers Squibb: Honoraria; Acceleron: Honoraria; Agios: Honoraria; Loxo Oncology: Honoraria; Onconova: Research Funding; Kura: Research Funding; Hoffman La Roche: Research Funding; Ariad: Research Funding; Biosight: Research Funding.

First relapse of B-ALL in children and AYAs is a vexing clinical problem with high rates of subsequent relapse and death using conventional treatment approaches. This is especially true in patients with early relapse [high risk (HR), defined as marrow relapse A total of 208 HR/IR patients were randomized (Arm A: 103, Arm B: 105). Baseline characteristics were comparable between arms (Table 1). With median follow up of 1.4 years, the intent-to-treat (ITT) 2-year DFS (% ± standard error) was 41.0 ± 6.2% for Arm A vs. 59.3 ± 5.4% for Arm B (p=0.05, 1-sided per pre-specified statistical plan)(Figure 1A). The ITT 2-year OS was 59.2 ± 6.0% for Arm A vs. 79.4 ± 4.5% for Arm B (p=0.005, 1-sided)(Figure 1B). Among patients with detectable MRD (≥0.01%) at the completion of Block 1 chemotherapy, the proportion that achieved undetectable MRD ( In conclusion, for children and AYA patients with HR/IR first relapse of B-ALL, blinatumomab is superior to standard chemotherapy as post-reinduction consolidation prior to HSCT, resulting in fewer and less severe toxicities, higher rates of MRD response, greater likelihood of proceeding to HSCT and improved disease-free and overall survival. Patients remain in follow up, and prospectively defined analyses of longer-term outcomes will be forthcoming. Disclosures Brown: Jazz: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Borowitz:Beckman Coulter: Honoraria. Raetz:Pfizer: Research Funding. Zugmaier:Amgen: Employment, Other: holds stock, Patents & Royalties: & other intellectual property. Gore:Amgen: Consultancy, Equity Ownership, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel expenses; Novartis: Consultancy, Other: Service on Data Safety Monitoring Committee; travel, accommodations, expenses; Roche/Genentech: Consultancy, Honoraria, Other: travel expenses; Anchiano: Equity Ownership, Other: spouse employment and company leadership; Blueprint Medicines: Equity Ownership; Celgene: Equity Ownership, Other: DSMC member; Clovis: Equity Ownership; Mirati: Equity Ownership; Sanofi Paris: Equity Ownership. Pulsipher:Medac: Honoraria; Miltenyi: Research Funding; Bellicum: Consultancy; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz: Other: Education for employees; Adaptive: Membership on an entity's Board of Directors or advisory committees, Research Funding; CSL Behring: Membership on an entity's Board of Directors or advisory committees; Amgen: Other: Lecture. Hunger:Amgen: Consultancy, Equity Ownership; Bristol Myers Squibb: Consultancy; Jazz: Honoraria; Novartis: Consultancy. Loh:Medisix Therapeutics, Inc.: Membership on an entity's Board of Directors or advisory committees. OffLabel Disclosure: Investigational use of blinatumomab

Background: The DIAL study is testing the efficacy of dual immunomodulation in patients with advanced aggressive B cell non-Hodgkin lymphoma (B-NHL). Sponsored by the Cancer Therapy Evaluation Program (CTEP), the trial combines the use of a programmed cell death protein 1 (PD-1) inhibitor (nivolumab) with an agonist of the CD27 receptor (varlilumab) in a randomized phase 2 design. CD27, a co-stimulatory receptor, regulates T cell activation in the context of T cell receptor (TCR) engagement through interaction with CD70. T cell exhaustion plays a major role in immune evasion in B-NHL. Varlilumab is an agonistic IgG1 monoclonal antibody that recognizes CD27 leading to prevention or reversal of exhaustion in pre-clinical models. Varlilumab also demonstrates direct anti-tumoral activity in xenograft models of human lymphoma cell lines via antibody-dependent cell-mediated cytotoxicity. Phase 1 data supports the safety and tolerability of single-agent varlilumab in advanced hematologic malignancies (NCT01460134). We hypothesize that CD27 activation synergizes with PD-1 inhibition resulting in a superior anti-lymphoma effect compared to PD-1 blockade alone. The study will also evaluate the effect of these agents on tumor and immune cells using immunohistochemistry (IHC), mass cytometry (CyTOF), multiplex ELISA, imaging mass cytometry (IMC), and whole exome sequencing. Methods: The trial is enrolling patients with advanced aggressive B-NHL. Standard inclusion criteria and prior treatment with at least 2 lines of standard therapy are required. Prior autologous stem cell transplant and/or chimeric antigen receptor (CAR) T cell therapy is allowed. Patients with active CNS disease are excluded. Eligible patients are randomized to treatment with single-agent nivolumab (group 1) or dual immunotherapy with nivolumab and varlilumab. Group 1 is allowed to cross-over at the time of progression. Nivolumab will be administered intravenously (IV) every 2 weeks (240 mg) for 4 months followed by monthly dosing thereafter (480 mg). Varlilumab will be given IV every 4 weeks (3 mg/kg). Response assessment will be done by PET-CT scan every 12 weeks. Primary outcome is overall response rate (ORR) according to the LYRIC criteria. The trial will enroll 48 patients per arm, allowing 80% power to detect at least 20% increase in ORR in the experimental arm (group 2) assuming a 25% ORR in the control arm (group 1). The trial is registered (NCT03038672) and open to participation to members of the Experimental Therapeutics Clinical Trials Network (ETCTN) and Early Drug Development Opportunity Program (EDDOP). Figure Disclosures Tun: BMS: Research Funding; Celgene: Research Funding; Curis: Research Funding; TG Therapeutics: Research Funding; Mundi-pharma: Research Funding; DTRM Biopharma: Research Funding. Bartlett:Pharmacyclics: Research Funding; Merck: Research Funding; Incyte: Research Funding; ADC Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Research Funding; Millennium: Research Funding; Kite Pharma: Research Funding; Janssen: Research Funding; Immune Design: Research Funding; Affimed: Research Funding; Autolus: Research Funding; Bristol-Myers Squibb: Research Funding; Celgene: Research Funding; Forty Seven: Research Funding; Genentech, Inc.: Research Funding; Gilead: Research Funding. Kline:Merck: Honoraria; Merck: Research Funding. Awan:Janssen: Consultancy; Gilead: Consultancy; Sunesis: Consultancy; Genentech: Consultancy; Abbvie: Consultancy, Speakers Bureau; Pharmacyclics: Consultancy, Research Funding; AstraZeneca: Consultancy, Speakers Bureau. Lazaryan:Kadmon: Consultancy. Ansell:Affimed: Research Funding; Affimed: Research Funding; Bristol-Myers Squibb: Research Funding; Mayo Clinic Rochester: Employment; Affimed: Research Funding; Bristol-Myers Squibb: Research Funding; Bristol-Myers Squibb: Research Funding; Affimed: Research Funding; Affimed: Research Funding; Affimed: Research Funding; LAM Therapeutics: Research Funding; Mayo Clinic Rochester: Employment; LAM Therapeutics: Research Funding; LAM Therapeutics: Research Funding; Seattle Genetics: Research Funding; LAM Therapeutics: Research Funding; Affimed: Research Funding; Bristol-Myers Squibb: Research Funding; LAM Therapeutics: Research Funding; Trillium: Research Funding; Regeneron: Research Funding; Regeneron: Research Funding; Regeneron: Research Funding; Regeneron: Research Funding; Bristol-Myers Squibb: Research Funding; Mayo Clinic Rochester: Employment; Seattle Genetics: Research Funding; Seattle Genetics: Research Funding; Regeneron: Research Funding; Seattle Genetics: Research Funding; LAM Therapeutics: Research Funding; Seattle Genetics: Research Funding; Affimed: Research Funding; Trillium: Research Funding; Trillium: Research Funding; LAM Therapeutics: Research Funding; Trillium: Research Funding; Trillium: Research Funding; Seattle Genetics: Research Funding; Mayo Clinic Rochester: Employment; Regeneron: Research Funding; Mayo Clinic Rochester: Employment; Regeneron: Research Funding; Bristol-Myers Squibb: Research Funding; Mayo Clinic Rochester: Employment; Mayo Clinic Rochester: Employment; Trillium: Research Funding; Seattle Genetics: Research Funding; Seattle Genetics: Research Funding; Mayo Clinic Rochester: Employment; Trillium: Research Funding; Mayo Clinic Rochester: Employment; LAM Therapeutics: Research Funding; Trillium: Research Funding; Seattle Genetics: Research Funding; Bristol-Myers Squibb: Research Funding; Affimed: Research Funding; Bristol-Myers Squibb: Research Funding; Regeneron: Research Funding; Bristol-Myers Squibb: Research Funding; LAM Therapeutics: Research Funding; Regeneron: Research Funding; Trillium: Research Funding. Diefenbach:Bristol-Myers Squibb: Consultancy, Research Funding; Denovo: Research Funding; Genentech: Consultancy, Research Funding; Incyte: Research Funding; LAM Therapeutics: Research Funding; MEI: Research Funding; Merck: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Millenium/Takeda: Research Funding; Trillium: Research Funding.

Introduction: Patients (pts) with HIV have a 6-fold increased risk of developing classic Hodgkin lymphoma (cHL) over the general population. The outcome of frontline therapy for HIV-associated cHL (HIV-cHL) using doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) is similar to the non-HIV population. However, pts with advanced stage cHL continue to have a 30% chance of refractory/relapsed disease with ABVD. Brentuximab vedotin (BV) is an anti-CD30 antibody drug conjugate that selectively induces apoptosis of CD30+ cells. The FDA approved BV with AVD (BV-AVD) after the Echelon-1 (E1) study for advanced stage disease demonstrated improved modified progression free survival (mPFS) at 2 years compared with standard ABVD: 82% vs. 77%. Pts with HIV were excluded from both relapsed/refractory and frontline BV trials. Here we present the final results of the phase 2 trial of BV-AVD in previously untreated HIV-associated cHL, an AIDS Malignancy Consortium/LYSA collaboration (ClinicalTrials.gov ID: NCT01771107). Methods: Forty-one pts were treated on days 1 and 15 of 6, 28 day cycles, with 1.2mgs/kg of BV in combination with doxorubicin 25 mg/m2, vinblastine 6 mg/m2, and dacarbazine 375 mg/m2 (AVD). Eligibility criteria included untreated cHL stage II-IV, CD4 + T-cell counts ≥50 cells/mm3, and initiation of combined antiretroviral therapy (cART) at least 1 week prior to therapy. Ritonavir, zidovidine, cobisistat, and other strong CYP3A4 or P-glycoprotein inhibitors were excluded with a washout of at least 1 week being required. Hematopoietic growth factor was mandated. The primary objective was 2 year PFS. The sample size was based on providing an estimate of the PFS with a 95% CI +/- 10% under the assumption of a 2 year progression free survival (PFS) estimate of 85%. Secondary objectives included toxicity, effects on CD4/CD8 + T-cells, HIV-1 viral load, prognostic significance of post C2 and end of treatment PET-CT. Results: Forty-one pts (93% men) were treated with a median age of 48y (range 24-67). Pts presented with stage II (17%), III (27%), and IV (56%) disease. Two year PFS estimate in the overall population (N=41) was 86% (95% CI: .74, .98). The 2-year overall survival (OS) estimate was 92% (95% CI: 0.83, 1.0) with 3 deaths at the time of analysis, including 1 which was a treatment related death (Figure 1A). For pts with advanced disease (N=34), the 2-year PFS estimate was 87% (95% CI: 0.76, 0.99) with an OS estimate of 90% (95% CI: 0.8, 1.00) (Figure 1B). Safety profiles were quite similar to the BV-AVD arm in the E1 study of the pts who received growth factor. Neuropathy was higher in our study compared to E1, (49% vs. 29% for any grade, P=0.01; 9.8% vs. 5% for G3/4, p=0.06). G3 Neutropenia was greater in AMC 085 compared to E1 BV-AVD arm with growth factor: 57% vs. 29% (p Conclusions: BV-AVD in stage II-IV HIV-cHL was efficacious although neutropenia and neuropathy were increased compared to the non-HIV population. The 2-year PFS estimate was 86% for the entire cohort and 87% for advanced stage HIV-cHL. Major interactions with strong CYP3A4 inhibitors lead to toxicity and must be avoided. The etiology of the CD4 increase is under investigation and may have implications for future therapy. Disclosures Rudek: Cullinan Apollo: Research Funding; Taiho: Research Funding; RenovoRX: Research Funding; Celgene: Research Funding. Barta:Mundipharma: Honoraria; Celgene: Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees; Takeda: Research Funding; Seattle Genetics: Honoraria, Research Funding; Bayer: Consultancy, Research Funding; Mundipharma: Honoraria; Merck: Research Funding; Celgene: Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees. Noy:Medscape: Honoraria; Janssen: Consultancy; Prime Oncology: Honoraria; NIH: Research Funding; Pharamcyclics: Research Funding; Raphael Pharma: Research Funding. OffLabel Disclosure: Brentuximab Vedotin has been approved for the upfront treatment of advanced stage cHL in combination with AVD though not specifically approved for use in patients infected with HIV or stage 2 cHL.

Background: Blinatumomab, a CD19/CD3 bispecific T cell engager antibody construct, leads to improved outcomes in patients with R/R CD19+ ALL compared to standard chemotherapy. However, most adults fail to achieve complete remission (CR) with blinatumomab, and the median duration of remission is only 7.3 months. Preclinical studies have shown significantly increased PD-L1 expression on leukemic blasts in patients who are refractory to or relapse after response to blinatumomab. Additionally, expression of the exhaustion markers PD-1 and TIM-3 on bone marrow (BM) CD3+ T cells is significantly higher among ALL patients than controls. The addition of PD-1 blockade +/- CTLA-4 blockade to blinatumomab and ALL blasts in vitro leads to increased T cell proliferation and enhanced blinatumomab-mediated cytotoxicity (Feucht et al, Oncotarget 2016). Thus, blockade of co-inhibitory pathways represents a viable strategy to enhance blinatumomab efficacy. We describe early results of a multi-center phase I study combining blinatumomab with monoclonal antibodies targeting PD-1 (nivolumab) +/- CTLA-4 (ipilimumab) in R/R CD19+ ALL. Methods: This phase I dose-escalation study evaluates the safety and tolerability (MTD) of blinatumomab in combination with nivolumab +/- ipilimumab using a 3+3 design. Patients ≥16 years-old with R/R CD19+ Pre-B ALL or MPAL are eligible including those with prior blinatumomab and/or prior allogeneic transplant (allo-SCT). Patients ≥60 years may be untreated and those 16-21 must be R/R to ³2 lines of therapy. The trial started at dose level (DL) A1 (Fig. 1). Upon determining the MTD for the combination of blinatumomab and nivolumab, dose escalation will add ipilimumab (DLB1). Patients may receive up to 5 cycles of blinatumomab and 1 year of nivolumab/ipilimumab. Patients achieving CR may proceed to allo-SCT. Patients removed from the study during the blinatumomab lead-in (days 1-10) will be replaced. Results: As of July 31, 2018, 8 adults (4 males/4 females) had enrolled at DLA1. The median age was 55 (range, 25-75) and baseline BM blast percentage was 73% (range, 8-98%). Baseline characteristics are presented in Figure 2. Seven patients received cytoreduction before treatment (6 steroids only and 1 steroids + Cytoxan). Two patients previously treated with blinatumomab were withdrawn from the study during the blinatumomab lead-in (1 for G3 pericardial effusion 2/2 disease progression and 1 for G3 hyperbilirubinemia). Among the 5 patients who received nivolumab to date, drug-related non-hematologic AEs of grade ≥3 included elevated AST (20%), ALT (20%), amylase (20%), and lipase (G4, 20%); hypophosphatemia (20%); rash (20%); infusion-related reaction (G4, 20%); and hypotension (20%). The elevated AST, ALT, amylase and lipase occurred prior to nivolumab dosing and resolved. One patient was removed from the study for a G4 infusion-related reaction following the 2nd dose of nivolumab that was considered a DLT. One patient in CR developed G4 neutropenia in cycles 2 + 3 but recovered spontaneously. Among the 5 evaluable patients, 4 (80%) achieved CR without MRD (2 after 1 cycle and 2 after 2 cycles of blinatumomab) with 3 ongoing remissions (median f/u 5 months) and 1 extramedullary relapse at day 125. Data on biomarkers including changes in T cell subpopulations in both BM and PB, and co-signaling molecule expression will be presented. Conclusions: Combination therapy with blinatumomab and nivolumab in R/R ALL with is feasible with acceptable toxicity. The MRD-negative CR rate was (80%) despite heavily pre-treated patients with significant baseline disease burden. The last patient treated at DLA1 is undergoing treatment before dose escalation to include ipilimumab. Disclosures DeAngelo: Shire: Honoraria; ARIAD: Consultancy, Research Funding; Takeda: Honoraria; BMS: Consultancy; Amgen: Consultancy; Blueprint Medicines: Honoraria, Research Funding; Pfizer Inc: Consultancy, Honoraria; Glycomimetics: Research Funding; Novartis Pharmaceuticals Corporation: Consultancy, Honoraria; Incyte: Consultancy, Honoraria. Luznik:WIndMIL Therapeutics: Equity Ownership, Patents & Royalties. Gojo:Amgen: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; Merck inc: Research Funding; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees.

Background: Current treatment of advanced stage Mycosis fungoides (MF) and Sézary syndrome (SS) remains unsatisfactory. Complete responses (CR) are typically Methods: This single-arm, multicenter study by the Cancer Immunotherapy Trials Network (CITN) enrolled 24 patients with MF/SS stages IB-IV, with at least one prior systemic therapy. Pembrolizumab was administered at 2 mg/kg every 3 weeks for up to two years. The primary endpoint was overall response rate (ORR) using global response criteria according to the ISCL/EORTC consensus guidelines. Skin responses were measured by mSWAT. Secondary endpoints were safety/tolerability, time to response (TTR), duration of response (DOR) and progression-free survival (PFS). Correlative studies included immunohistochemistry (IHC), mass cytometry, whole exome sequencing, gene expression profiling, and serum cytokine analysis. Results: Patients had advanced stage disease (23/24 with stage IIB-IV MF/SS), and were heavily pretreated (median of 4 prior systemic therapies). The ORR was 38% with 2 CR and 7 PR. Of the 9 responding patients, 6 had ≥90% improvement in skin disease by mSWAT. The median TTR was 11 weeks. Responses were durable, with 8 of 9 responses ongoing at last follow up (median DOR 64 weeks, range 32-153 weeks). One responding patient progressed 2 months after discontinuing treatment due to an adverse event (AE). The median PFS was not reached. Overall, the toxicity profile was similar to prior studies of pembrolizumab. Four patients discontinued treatment due to treatment related serious AEs of duodenitis, pneumonitis, hepatitis, and corneal ulcer. Skin flare reactions were observed early in the treatment course in 40% of patients with SS, but none with MF. The skin flare reactions did not result in any treatment discontinuation, and did not correlate with subsequent response to treatment. There was no significant association between response and clinical characteristics including stage, disease type (MF vs. SS), or number of prior therapies. IHC assessment of PD-1, PD-L1, and PD-L2 did not predict response. Treatment resulted in an increase of PD-L1 expression by both IHC and nanoString analysis. A nanoString18 gene signature of tumor inflammation that is predictive of response to pembrolizumab in other tumor types was not predictive in this cohort. High dimensional mass cytometry enabled precise identification and phenotyping of malignant T cells. There was a positive correlation between PD-1 expression on the malignant T cells and development of the skin flare reaction. Whole exome sequencing revealed genomic disruptions of PD-1 signaling including copy loss of PD-1. No associations were found between outcomes and genomic events involving the PD1/PD-L1 axis, total mutation number, or neoantigen numbers. Conclusions: The 38% ORR rate in this heavily pretreated population was 38% with a highly encouraging DOR of 64 weeks. No predictive biomarkers have emerged thus far, but additional studies are ongoing. Additional combination studies with pembrolizumab are warranted to improve response rates. Figure. Figure. Disclosures Khodadoust: Innate Pharma: Research Funding. Porcu:Innate Pharma: Consultancy. Foss:Miragen: Consultancy, Speakers Bureau; Seattle genetics: Consultancy; Spectrum: Consultancy; Mallinkrodt: Consultancy. Moskowitz:Bristol Myers-Squibb: Consultancy, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Incyte: Research Funding; Merck: Research Funding; Takeda: Honoraria; ADC Therapeutics: Research Funding. Shustov:Seattle Genetics: Research Funding. Sokol:Seattle Genetics: Consultancy; Mallinckrodt Pharmaceuticals: Consultancy; Spectrum Pharmaceuticals: Consultancy. Yearley:Merck: Employment. Horwitz:Mundipharma: Consultancy; Celgene: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; ADC Therapeutics: Consultancy, Research Funding; Kyowa-Hakka-Kirin: Consultancy, Research Funding; Forty Seven: Consultancy, Research Funding; Millennium/Takeda: Consultancy, Research Funding; Infinity/Verastem: Consultancy, Research Funding; Aileron Therapeutics: Consultancy, Research Funding; Portola: Consultancy; Trillium: Consultancy; Innate Pharma: Consultancy; Spectrum: Research Funding; Corvus: Consultancy. Kim:miRagen: Research Funding; Horizon Pharma: Consultancy, Research Funding; Neumedicine: Consultancy, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Galderma: Research Funding; Soligenix: Research Funding; Eisai: Membership on an entity's Board of Directors or advisory committees, Research Funding; Tetralogic: Research Funding; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees; Portola: Research Funding; Merck: Research Funding; Medivir: Membership on an entity's Board of Directors or advisory committees; Kyowa-Kirin-Pharma: Membership on an entity's Board of Directors or advisory committees, Research Funding; Innate Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Forty Seven Inc: Research Funding.

Background:PD-1 and PD-L1/PD-L2 are expressed by malignant T-cells in mycosis fungoides (MF) and Sézary syndrome (SS). PD-1 is additionally expressed by tumor-infiltrating cytotoxic T-cells and PD-L1 is expressed by macrophages and other stromal components of the tumor microenvironment in these diseases. Moreover, reports of 9p24.1/PD-L2 translocation and CTLA4-CD28 fusion events in MF/SS support a genomic basis for immune evasion. Here, we explore the clinical activity of pembrolizumab, an immune checkpoint inhibitor of the PD-1/PD-L1 axis, in MF/SS. Methods:Patients (pts) with MF/SS stages IB-IV treated with at least 1 prior systemic therapy were enrolled in this phase 2, single-arm study coordinated by the Cancer Immunotherapy Trials Network (CITN). A Simon two-stage design was applied where stage 2 is initiated if 1 of 9 pts had an objective response. An additional 15 pts were planned in stage 2. Pembrolizumab was administered at 2 mg/kg every 3 weeks and treatment was allowed up to 2 years. The primary endpoint was overall response rate (ORR) as determined by the consensus global response criteria. Secondary endpoints were safety/tolerability, time to response (TTR), duration of response (DOR) and progression-free survival (PFS). Correlative biomarker studies included immunohistochemistry (IHC) staining for PD-L1, PD-L2, and multiple immune subsets as well as serum analysis of 62 cytokines and chemokines. Phenotypic and functional profiling of malignant and non-malignant immune cells will be performed by flow cytometry and mass cytometry (CyTOF). Results: The study completed enrollment and all 24 patients received at least one dose of pembrolizumab. Median age was 67 (range 44-85); 18 were male. Patients were advanced stage with 23 patients (96%) stage IIB or higher, including 15 patients (63%) with stage IVA SS. Most pts were heavily treated with a median of 4 prior systemic therapies (range 1-11). The median follow-up time was 40 weeks (range 9-60 weeks). The objective response rate (ORR) was 38% with 1 complete response (CR) and 8 partial responses (PR). Of the responding pts, 6 pts had 90% or greater improvement in skin disease as measured by mSWAT. An additional 9 pts (38%) had stable disease (SD). The median TTR was 11 weeks (range 8-41 weeks). Responses were durable with 8 of 9 (89%) responses currently ongoing at a median of 32 weeks of duration (4-46). The median PFS has not yet been reached, and the one-year PFS was 69%. There was no significant association between response and clinical characteristics including stage, disease type (MF vs. SS), and number of prior therapies, nor with skin tissue expression of PD-1, PD-L1, PD-L2, or infiltrating CD8+ T-cells as determined by IHC. Planned additional correlatives including CyTOF profiling, gene expression profiling, T cell receptor high throughput sequencing, multiplexed ion beam imaging (MIBI), and whole exome sequencing will explore potential predictive biomarkers of response. Adverse events (AE) were consistent with those seen in prior studies of pembrolizumab with the exception of an immune-mediated skin flare reaction seen in 6 pts (2 grade 2 and 4 grade 3). Skin flares occurred exclusively in patients with SS (6/15; 40%) and were associated with lower serum levels of the cytokines IL-7 and SCF prior to pembrolizumab treatment (p=0.01 and p=0.02 respectively, n.s. by Bonferroni correction). Pts with the skin flare reaction experienced increases in serum IFN-gamma, IL-12p40, IL-15, LIF, G-CSF, and CCL4 following treatment. There were two treatment related serious adverse events (SAE), both immune related. One pt experienced grade 2 pneumonitis which resolved with systemic corticosteroids. Another patient experienced grade 3 diarrhea secondary to steroid-refractory duodenitis. Conclusions: Pembrolizumab has significant clinical activity in pts with previously treated MF/SS. Responses were durable and were not associated with any identifiable clinical or pathologic characteristics. Treatment was well tolerated with a toxicity profile consistent with prior pembrolizumab studies, though 40% of pts with SS developed a notable skin flare reaction. These findings support further study of PD-1 blockade in the treatment of MF and SS. A phase 2 trial of pembrolizumab in combination with interferon-gamma is being developed based on these results. Disclosures Porcu: Millenium: Other: investigator in a clinical trial; miRagen: Other: Investigator in a clinical trial; celgene: Other: Investigator in a clinical trial; Innate Pharma: Other: Investigator in a clinical trial. Foss:Celgene: Consultancy, Research Funding, Speakers Bureau; Eisai: Consultancy; Seattle Genetics: Consultancy, Speakers Bureau; Spectrum Pharmaceuticals: Consultancy. Moskowitz:Bristol Myers Squibb: Honoraria; Merck: Honoraria; Seattle Genetics: Honoraria, Research Funding. Sokol:Seattle Genetics: Consultancy; Spectrum: Consultancy. Yearley:Merck: Employment. Chartash:Merck: Employment. Townson:Merck: Employment. Horwitz:Spectrum: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy; Huya: Consultancy; Infinity: Consultancy, Research Funding; Kyowa Hakka Kirin: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Seattle Genetics: Consultancy, Research Funding; Celgene: Consultancy; ADCT Therapeutics: Research Funding. Kim:Seattle Genetics: Consultancy, Other: Investigator in a clinical trial; Merck: Other: Investigator in a clinical trial; Neumedicine: Consultancy; Soligenix: Consultancy; Galderma: Consultancy; Genentech: Other: Investigator in a clinical trial; Innate Pharma: Other: Investigator in a clinical trial; Kyowa Hakko Kirin: Consultancy, Honoraria, Other, Research Funding; Millenium: Consultancy, Other: Investigator in a clinical trial; Eisai: Consultancy, Other: Investigator in a clinical trial; Actelion: Consultancy, Other: Investigator in a clinical trial; Celgene: Consultancy; MiRagen: Consultancy; Horizon: Consultancy.

Introduction: Patients (pts) infected with HIV have a 6-8 fold increased risk of classic Hodgkin lymphoma (cHL). Incidence may have increased with the implementation of combined anti-retroviral therapy (cART) in the mid 1990s. Frontline therapy for HIV-associated cHL (HIV-cHL) using, doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) in the pre-cART era showed a 2 year overall survival (OS) of 48%, but outcomes are currently similar to the non-HIV population. Pts with advanced disease have a 30% chance of relapse with ABVD. Brentuximab vedotin (BV), an anti-CD30 an antibody drug conjugate that selectively induces apoptosis of CD30+ cells with a complete response of 34% in patients with relapsed/refractory cHL. An international trial of BV with doxorubicin, vinblastine, and dacarbazine (AVD) vs. ABVD is ongoing. Here we present the phase I portion of the first trial using BV with AVD in the upfront treatment of HIV-cHL. The Phase II portion is actively accruing in both the United States and France as part of an AIDS Malignancy Consortium (AMC)/Lymphoma Study Association (LYSA) collaboration. Methods: The Phase I was a 3+3 dose de-escalation design evaluating 3 dose levels of BV (1.2 mg/kg, 0.9 mg/kg, and 0.6 mg/kg) every 2 weeks combined with standard, fixed doses of doxorubicin 25 mg/m2, vinblastine 6 mg/m2, and dacarbazine 375 mg/m2 (AVD) in a 28 day cycle. Eligibility: HIV+ pts diagnosed with untreated cHL stage II-IV with CD4 counts ≥50 cells/mm3 were required to take cART regimens for at least 1 week before treatment. Ritonavir, zidovidine, and cobisistat were excluded. Baseline, cycle 2, and post treatment PET/CT scans were required. Dose limiting toxicities (DLTs) were defined during cycle 1. Results: Sixpts (5 men and 1 woman) were treated in the phase I portion from 3/2013-5/2015. Staging: II (n=1), III (n=1) IV (n=4). Pathology: mixed cellularity (n=2), nodular sclerosis (n=3), and lymphocyte depleted/mixed cellularity (n=1) HIV-cHL. The median CD4 T cell count at lymphoma diagnosis was 499 cells/mm3 (range 86-784) and the median viral load was 44 copies/ml (range 20-77). No cycle 1 DLTs were identified in the first 6 eligible patients and only 3 grade 3 adverse events in later cycles were noted, pneumonia, n=1, and neuropathy n=2, and neutropenia, n=1. In 2 pts, toxicity required delays in therapy of over 3 weeks (after c5d1 and after c6d1) resulting in subject removal from further protocol therapy. One pt had a decrease in the diffusion lung capacity for carbon monoxide (DLCO) to 65% after cycle 2, and BV was withheld while AVD continued as per protocol. Two pts were later deemed ineligible, and excluded from any analysis, due to the concomitant use of ritonavir-based cART at enrollment. Both developed febrile neutropenia and one developed a grade 3 pancreatitis during cycle 1, emphasizing the importance of not treating patients with BV + AVD with concurrent CYP3A4 inhibitors. Five of the 6 pts achieved cycle 2 PET/CT negativity as defined by a Deauville score 1-3. The PET/CT positive patient ultimately had a negative post-therapy scan. The 5 pts who completed therapy achieved CR post-therapy, and one patient has yet to complete treatment. Phase II is enrolling at BV 1.2 mg/kg in combination with AVD. Conclusions: AVD-BV in stage II-IV HIV-cHL was well-tolerated therapy as no DLT were identified. Five of the 6 patients achieved a negative C2 PET/CT and 5/5 of the patients who completed therapy thus far achieved a CR. The recommended Phase II dose is 1.2 mg/kg +AVD every other week. The phase II portion (51 subjects) is actively accruing in both the USA and France, in an AMC/LYSA collaboration, clinicaltrials.gov NCT01771107. Disclosures No relevant conflicts of interest to declare.