Abstract: Abstract 203 Background: Oprozomib (OPZ, formerly ONX 0912), a structural analog of carfilzomib (CFZ), is an orally bioavailable, next-generation proteasome inhibitor being evaluated in hematologic malignancies and solid tumors. Similar to CFZ, OPZ is a potent, selective, and irreversible proteasome inhibitor. In an earlier dose-escalation study of once-daily (QD) OPZ in patients with advanced refractory solid tumors, the maximum tolerated dose (MTD) was 150 mg QD, leading to exploration of a split-dose schedule with the drug administered twice daily (BID). The present phase 1 study (NCT01416428) is evaluating OPZ administered using the split-dose schedule in patients with hematologic malignancies. Methods: This is an ongoing, phase 1b, open-label, dose-escalation study of OPZ in patients with hematologic malignancies. The primary objectives are to evaluate safety and tolerability and to determine the MTD. Secondary objectives of the study include pharmacokinetic and pharmacodynamic analyses. OPZ is administered PO on days 1–5 of a 14-day cycle using a standard 3 + 3 dose-escalation scheme. Treatment was initiated at 120 mg (60 mg BID), with an interval of 4–6 h between doses, with escalation in 30-mg increments in successive cohorts until MTD is determined. Tumor response is assessed by investigator. Results: As of June 15, 2012, 9 patients have been enrolled in the study, 3 in each of the 120-mg, 150-mg, and 180-mg dosing cohorts. No dose-limiting toxicities have been observed. Enrollment is ongoing at 210 mg/day. The median age of all patients is 67 years (range 53−81) and prior therapies included a median of 4 chemotherapy regimens (range 2−8). Patients have received a median of 5 cycles of treatment with OPZ, including 4 patients who have received ≥6 cycles. Dose reduction was required by only 1 patient in the 180-mg (90 mg BID) group for Grade 3 diarrhea and abdominal pain. Gastrointestinal (GI) AEs predominantly of Grade 1/2 in severity were the most common, with diarrhea and nausea each occurring in 7 patients, and vomiting occurring in 6 patients. The majority of GI AEs improved or resolved with concomitant medications. Thrombocytopenia was the only Grade 3/4 AE reported in more than 1 patient, occurring in 3 patients (1 at each dose level). Notably, no events of peripheral neuropathy were noted in patients in the first 3 dosing cohorts. AEs led to discontinuation in 2 patients at the 180-mg dose level, and no deaths have been reported. OPZ showed dose-dependent exposure across the 120- to 180-mg dose levels. Patients receiving split dosing had similar total exposure and lower Cmax than patients receiving QD dosing of the same total daily dose, although there was high inter-patient variability. Dose-dependent proteasome inhibition was observed in whole blood and increased from the first to the second of the split daily doses. Proteasome inhibition levels were similar to those achieved with single-dose equivalents and were 〉 80% at the 180-mg dose level. Eight of 9 patients are evaluable for efficacy. There was preliminary evidence of anti-tumor activity of ≥SD across all doses, including 1 patient with chronic lymphocytic leukemia who attained a PR after prior exposure to 3 lines of therapy, and 1 PR and 1 MR in patients with multiple myeloma. Conclusions: Oral OPZ was generally well tolerated using a split-dose schedule in this phase 1 trial in patients with hematologic malignancies. AEs were generally mild and manageable. An MTD has not been reached at cumulative doses up to 180 mg/d (90 mg BID). Dose-dependent proteasome inhibition was observed, with 〉 80% inhibition at the highest dose tested. OPZ also demonstrated encouraging clinical activity across the first 3 dose levels in heavily pretreated patients. Dose escalation will continue until the MTD is reached, with planned phase 2 expansion at the MTD in patients with hematologic malignancies. Disclosures: Off Label Use: Oprozomib is in Phase 1 clinical trials for hematologic malignancies and is not approved by the FDA for any use. Lee:Onyx Pharmaceuticals: Employment. Wong:Onyx Pharmaceuticals: Employment. Lee:Onyx Pharmaceuticals: Employment. Gillenwater:Onyx Pharmaceuticals: Employment. Siegel:Onyx: Advisory Board, Advisory Board Other, Honoraria, Speakers Bureau; Millennium Pharma: Advisory Board, Advisory Board Other, Honoraria, Speakers Bureau; Celgene: Advisory Board Other, Honoraria, Speakers Bureau; Merck: Advisory Board, Advisory Board Other, Honoraria, Speakers Bureau.

Abstract: Abstract 5068 Proteasome inhibition has been validated as a therapeutic approach for multiple myeloma (MM) and mantle cell lymphoma, however the contributions of inhibiting individual active-site subunits of the constitutive proteasome (c20S) and the immunoproteasome (i20S) has not been fully explored due the lack of effective tools. A novel assay was developed, validated, and used to quantitatively measure the levels of individual proteasome active site subunits in vitro and in tissue samples from patients exposed to the proteasome inhibitor (PI) carfilzomib from 5 clinical trials, PX-171-003, PX-171-004, PX-171-005, PX-171-006 & PX-171-007. This assay, called ProCISE (proteasome constitutive/immune subunit ELISA), was shown to have good analytical recovery without interfering matrix effects and was used to measure the activity of c20S subunits (b5, b2 and b1) and i20S subunits (LMP7, MECL1 and LMP2) using subunit-specific antibodies in whole blood, PBMC, and bone marrow derived CD138+ MM cells. Following an initial dose of carfilzomib across doses of 15 – 45 mg/m2, ≥80% inhibition of the chymotrypsin-like (CT-L) active sites b5 and LMP7 as well as dose-dependent inhibition of MECL1 and LMP2 was observed. Additionally, neither renal function nor co-administration of the commonly used MM agents, lenalidomide or dexamethasone, had an effect on the pharmacodynamics of carfilzomib. Carfilzomib inhibited 63% of all active sites of the immunoproteasome at 45 mg/m2 and 78% at 56mg/m2. In tumor cells, which express a mixture of both proteasome types, inhibition of CT-L activity correlated with levels of inhibition in whole blood. Proteasome inhibition with carfilzomib was prolonged in both whole blood and PBMC. Cumulative and sustained proteasome inhibition was seen in whole blood while complete or near complete recovery was noted in PBMC by the start of a second cycle of administration. The depth and duration of proteasome inhibition with carfilzomib is greater than what has been reported with the reversible inhibitor bortezomib. In a limited analysis of MM patients, stratified by best response to carfilzomib, we did not detect a difference in the full proteasome inhibition profile in patients achieving an objective response and those that did not achieve clinical benefit. While these data do not currently demonstrate that proteasome inhibition alone is a predictive marker of clinical response, with larger sample sizes and further investigation regarding subunit-specific inhibition of the proteasome, we hope to be able to demonstrate a correlation between proteasome inhibition and patient response. Disclosures: Lee: Onyx Pharmaceuticals: Employment, Equity Ownership. Woo:Onyx Pharmaceuticals: Employment, Equity Ownership. Arastu-Kapur:Onyx Pharmaceuticals: Employment, Equity Ownership. Wong:Onyx Pharmaceuticals: Employment, Equity Ownership. Renau:Onyx Pharmaceuticals: Employment, Equity Ownership. Kirk:Onyx Pharmaceuticals: Employment, Equity Ownership.

Abstract: Carfilzomib is a proteasome inhibitor in clinical development that primarily targets the chymotrypsin-like (CT-L) subunits in both the constitutive proteasome (c20S) and the immunoproteasome (i20S). To investigate the impact of inhibiting the CT-L activity with carfilzomib, we set out to quantitate the levels of CT-L subunits β5 from the c20S and LMP7 from the i20S in normal and malignant hematopoietic cells. We found that the i20S is a major form of the proteasome expressed in cells of hematopoietic origin, including multiple myeloma (MM) CD138+ tumor cells. Although specific inhibition of either LMP7 or β5 alone was insufficient to produce an antitumor response, inhibition of all proteasome subunits was cytotoxic to both hematologic tumor cells and peripheral blood mononuclear cells. However, selective inhibition of both β5 and LMP7 was sufficient to induce an antitumor effect in MM, non-Hodgkin lymphoma, and leukemia cells while minimizing the toxicity toward nontransformed cells. In MM tumor cells, CT-L inhibition alone was sufficient to induce proapoptotic sequelae, including proteasome substrate accumulation, Noxa and caspase 3/7 induction, and phospho-eIF2α suppression. These data support a hypothesis that hematologic tumor cells are uniquely sensitive to CT-L inhibition and provide a mechanistic understanding of the clinical safety profile and antitumor activity of proteasome inhibitors.

Abstract: Background: Autologous CD19-targeting chimeric antigen receptor T cell (CAR-T) products are approved as standard treatment options for patients (pts) with relapsed diffuse large cell lymphoma (DLBCL), mantle cell lymphoma (MCL), and follicular lymphoma (FL). Their long-term efficacy for DLBCL is ~40% and is unknown for other histologies. Additionally, associated toxicities including cytokine-release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) remain a challenge. CD20 is a proven target for treatment of B-NHLs/CLL with demonstrated high clinical efficacy of unmodified, radiolabeled, and bispecific antibodies. Therefore, CD20-targeted CAR-T represents a promising adoptive immunotherapy option that could be utilized to treat relapsed/refractory (R/R) B-NHLs and CLL. MB-106 is a fully human 3rd-generation CD20-targeted CAR-T product with both 4-1BB and CD28 costimulatory domains. We present results of our ongoing phase I/II clinical trial investigating safety and efficacy of CD20 CAR-T for high-risk B-NHLs and CLL (NCT03277729). Methods: Pts with R/R CD20+ B-cell malignancies are eligible, including but not limited to DLBCL, FL, MCL, and CLL. Prior treatment with CD19 CAR-T is permitted. Lymphodepletion (LD) consists of cyclophosphamide (Cy) ± fludarabine (Flu). CAR-T cells are administered at one of 4 dose levels (DL): DL1: 3.3x10 5, DL2: 1x10 6, DL3: 3.3x10 6, DL4: 1x10 7 CAR T cells/kg. A continual reassessment method dose escalation design was used to find the maximally tolerated dose. CAR-T is infused in the outpatient setting except for the first pt of each dose cohort (overnight observation). Treatment response is assessed on day 28. CRS and ICANS are graded per ASTCT consensus grading. The study underwent a major cell manufacturing modification after treating 7 pts with no objective responses as previously reported (Shadman, ASH 2020, #1443). This abstract includes pts who were treated under the modified process. Results: Between Dec 2019 and July 2021, 16 pts (12 FL, 2 MCL, 1 CLL, 1 DLBCL) were treated after LD with Cy-Flu and had day 28 assessment. All DLs were reached (see table), with no dose-limiting toxicities to date. CRS occurred in 7 pts (44%): 4 pts with grade (Gr) 1 and 3 with Gr 2. ICANS was observed in 1 pt (6.2%) at Gr 2. There were no Gr 3 or Gr 4 CRS or ICANS. Median time to CRS was 6.5 days (range, 0-12); the 1 ICANS event occurred on day 12. One pt (CLL) developed Gr 3 temporary neuropathic pain which, in the absence of other explanation, was attributed to the CAR-T. No pts had tumor lysis syndrome or Gr 3-4 infections. Thrombocytopenia (Gr 3-4: 19%) and neutropenia (Gr 3-4: 94%) were common but there were no bleeding complications, and the rate of febrile neutropenia was 19%. Overall response (ORR) was 94% (15/16) with complete response (CR) rate of 62% (10/16). In FL pts (n =12), ORR was 92% (11/12) and CR rate was 75% (9/12). Among FL pts who received DL 3 or 4, the CR rate was 86%. The CLL pt had a PET-negative CR and undetectable measurable residual disease in peripheral blood and bone marrow by flow cytometry (10 -4) (uMRD4) on day 28. The pt with DLBCL achieved a partial response (PR) on day 28 and a repeat PET on day ~ 90 showed continued improvement but still indicating a PR. Among pts who achieved a CR, only one pt (FL) relapsed after 9 months. All other CRs are ongoing (range: 3-18 months). CAR-T persistence was lost at day 95 in 1 pt who had progression and proceeded to other anti-lymphoma treatment; 2 other patients lost CAR-T engraftment by day 181 and 201 with B cell recovery. All other patients continue to have detectable CAR-T cells as of last follow-up (max 13 months post-infusion). Conclusion: Treatment with MB-106 shows a favorable safety profile with no Gr 3 or Gr 4 CRS or ICANS. In addition, we observed a high rate of ORR and CR with ongoing CRs and high rate of CAR-T persistence. Enrollment is currently ongoing; data will be updated at the time of presentation. Figure 1 Figure 1. Disclosures Shadman: Mustang Bio, Celgene, Bristol Myers Squibb, Pharmacyclics, Gilead, Genentech, Abbvie, TG Therapeutics, Beigene, AstraZeneca, Sunesis, Atara Biotherapeutics, GenMab: Research Funding; Abbvie, Genentech, AstraZeneca, Sound Biologics, Pharmacyclics, Beigene, Bristol Myers Squibb, Morphosys, TG Therapeutics, Innate Pharma, Kite Pharma, Adaptive Biotechnologies, Epizyme, Eli Lilly, Adaptimmune , Mustang Bio and Atara Biotherapeutics: Consultancy. Yeung: Merck,Celgene: Consultancy. Ujjani: ACDT: Honoraria; Gilead: Honoraria; TG Therapeutics: Honoraria; Janssen: Consultancy; Epizyme: Consultancy, Membership on an entity's Board of Directors or advisory committees; Atara Bio: Consultancy; Loxo: Research Funding; Adaptive Biotechnologies: Research Funding; Kite, a Gilead Company: Honoraria; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding. Dezube: Mustang Bio: Current Employment, Current holder of individual stocks in a privately-held company. Poh: Acrotech: Honoraria; Incyte: Research Funding; Morphosys: Consultancy. Chapuis: Karkinos Therapeutics: Other: Ownership; Lonza: Other: Intellectual Property; Cullian: Other: Intellectual Property; TScan Therapeutics, Inc.: Consultancy, Other: Ownership; SignalOne Bio: Consultancy, Other: Ownership; Bluebird bio: Other: Intellectual Property; Juno therapeutics: Other: Intellectual Property; Adapyive Biotechnologies Corporation: Other: Ownership/Intellectual Property; Pfizer: Other: Intellectual Property; Affini-T: Other: Ownership; Ridgeline: Consultancy; BioNTech: Consultancy. Green: Seagen Inc.: Research Funding; bristol myers squibb: Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; Cellectar Biosciences: Research Funding; GSK: Membership on an entity's Board of Directors or advisory committees; Janssen Biotech: Membership on an entity's Board of Directors or advisory committees, Research Funding; Juno Therapeutics: Patents & Royalties, Research Funding; Legend Biotech: Consultancy; Neoleukin Therapeutics: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; SpringWorks Therapeutics: Research Funding. Cowan: Abbvie: Consultancy, Research Funding; Harpoon: Research Funding; Janssen: Consultancy, Research Funding; Sanofi Aventis: Consultancy, Research Funding; Bristol Myers Squibb: Research Funding; Nektar: Research Funding; GSK: Consultancy; Secura Bio: Consultancy; Cellectar: Consultancy. Cassaday: Amgen: Consultancy, Research Funding; Servier: Research Funding; Vanda Pharmaceuticals: Research Funding; Pfizer: Consultancy, Research Funding; Kite/Gilead: Consultancy, Honoraria, Research Funding; Pepromene Bio: Membership on an entity's Board of Directors or advisory committees; Merck: Research Funding. Kiem: Homology Medicines: Consultancy; VOR Biopharma: Consultancy; Ensoma Inc.: Consultancy, Current holder of individual stocks in a privately-held company. Gauthier: Janssen: Membership on an entity's Board of Directors or advisory committees; Multerra Bio: Consultancy; Legend Biotech: Membership on an entity's Board of Directors or advisory committees; Larvol: Consultancy; JMP: Consultancy; Eusapharma: Consultancy. Turtle: T-CURX: Other: Scientific Advisory Board; Century Therapeutics: Consultancy, Other: Scientific Advisory Board; Arsenal Bio: Current holder of stock options in a privately-held company, Other: Scientific Advisory Board; Eureka Therapeutics: Current holder of stock options in a privately-held company, Other: Scientific Advisory Board; Nektar Therapeutics: Consultancy, Research Funding; Precision Biosciences: Current holder of stock options in a privately-held company, Other: Scientific Advisory Board; Caribou Biosciences: Consultancy, Current holder of stock options in a privately-held company, Other: Scientific Advisory Board; Juno Therapeutics/BMS: Patents & Royalties: Right to receive royalties from Fred Hutch for patents licensed to Juno Therapeutics, Research Funding; AstraZeneca: Consultancy, Research Funding; Myeloid Therapeutics: Current holder of stock options in a privately-held company, Other: Scientific Advisory Board; Asher Bio: Consultancy; Amgen: Consultancy; PACT Pharma: Consultancy; TCR2 Therapeutics: Research Funding; Allogene: Consultancy. Lynch: TG Therapeutics: Research Funding; Bayer: Research Funding; Incyte: Research Funding; Juno Therapetics: Research Funding; Morphosys: Consultancy; Genentech: Research Funding; SeaGen: Research Funding; Cyteir: Research Funding. Smith: Portola Pharmaceuticals: Research Funding; Acerta Pharma BV: Research Funding; ADC Therapeutics: Consultancy; Incyte Corporation: Research Funding; AstraZeneca: Consultancy, Research Funding; Incyte: Consultancy; Ayala (spouse): Research Funding; Merck Sharp & Dohme Corp: Research Funding; Bristol Myers Squibb (spouse): Research Funding; De Novo Biopharma: Research Funding; Ignyta (spouse): Research Funding; KITE pharm: Consultancy; Millenium/Takeda: Consultancy; Bayer: Research Funding; Karyopharm: Consultancy; Beigene: Consultancy, Research Funding; Genentech: Research Funding. Gopal: Gilead: Consultancy, Honoraria, Research Funding; Genetech: Consultancy, Honoraria, Research Funding; SeaGen: Consultancy, Honoraria, Research Funding; Astra-Zeneca: Research Funding; Bristol Meyers Squibb: Research Funding; Agios: Research Funding; MorphoSys: Honoraria; IGM Biosciences: Research Funding; ADC Therapeutics: Consultancy, Honoraria; Acrotech: Consultancy, Honoraria; Karyopharm: Consultancy, Honoraria; Merck: Consultancy, Honoraria, Research Funding; Kite: Consultancy, Honoraria; Servier: Consultancy, Honoraria; Nurix Inc: Consultancy, Honoraria; Takeda: Research Funding; Teva: Research Funding; I-Mab bio: Consultancy, Honoraria, Research Funding; Epizyme: Consultancy, Honoraria; Incyte: Honoraria; Beigene: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Research Funding; Cellectar: Consultancy, Honoraria. Maloney: BioLineRx, Juno, Celgene, Kite, a Gilead Company, Gilead, Novartis, and Pharmacyclics: Honoraria; A2 Biotherapeutics: Consultancy; Kite, a Gilead Company, Juno, and Celgene: Research Funding; Juno: Patents & Royalties; A2 Biotherapeutics: Divested equity in a private or publicly-traded company in the past 24 months. Till: Mustang Bio: Consultancy, Patents & Royalties, Research Funding.

Abstract: Transcranial Doppler (TCD) screening in children with sickle cell anemia (SCA) identifies abnormally elevated cerebral artery flow velocities that confer an elevated risk for primary stroke. Chronic transfusions offer effective stroke prophylaxis in this setting, but must be continued indefinitely and lead to transfusional iron overload. An alternative treatment strategy that offers similar effective protection against primary stroke, and provides control of iron overload, is needed. TCD With Transfusions Changing to Hydroxyurea (TWiTCH, NCT01425307) was an NHLBI-funded Phase III multicenter randomized clinical trial comparing 24-months of standard treatment (transfusions) to alternative treatment (hydroxyurea) in children with SCA and abnormal TCD velocities. All eligible children had received at least 12 months of transfusions. TWiTCH had a non-inferiority trial design; the primary study endpoint was the 24-month TCD velocity obtained from a linear mixed model, controlling for baseline (enrollment) values, with a non-inferiority margin of 15 cm/sec. The transfusion arm maintained children at HbS 〈 30%; an elevated liver iron concentration (LIC) identified by R2 MRI FerriScan® was managed with chelation. The hydroxyurea arm included an overlap period with transfusions until a stable maximum tolerated dose (MTD) of hydroxyurea was reached; transfusions were then replaced by serial phlebotomy to reduce iron overload. In both arms, TCD velocities were obtained every 12 weeks and reviewed centrally, with local investigators masked to the results. A centralized TCD alert algorithm monitored changes from enrollment velocities. A total of 159 children were enrolled but 38 failed screening due primarily to severe vasculopathy on brain MRA or inadequate TCD exams; 121 children were randomized (61 to transfusions, 60 to hydroxyurea) with balanced characteristics including enrollment maximum TCD velocities (145 ± 21 versus 145 ± 26 cm/sec), age, duration of transfusions, serum ferritin, and LIC. Study participants randomized to transfusions maintained an average HbS 〈 30% throughout the study, while those on hydroxyurea reached MTD after 7 ± 2 months at an average dose of 27 mg/kg/day, with expected hematological changes including HbF ~25% throughout the treatment period. After 37% of the participants exited the study, a scheduled interim analysis suggested the primary study endpoint was likely to be achieved. NHLBI allowed the study to continue until 50% of the children exited, at which time the statistical analysis was confirmed and the study was terminated; all remaining participants moved to the exit phase. The final analysis included 42 on the transfusion arm who completed all treatment, 11 with truncated treatment, and 8 withdrawn; the hydroxyurea arm included 41 who completed all treatment, 13 with truncated treatment, and 6 withdrawn. The final calculated TCD velocities (mean ± standard error) in the transfusion and hydroxyurea arms were 143 ± 1.6 and 138 ± 1.6 cm/sec, respectively; by intention-to-treat analysis, the p-value for non-inferiority = 8.82 x 10-16 and by post-hoc analysis the p-value for superiority = 0.046. Among 29 new neurological events, all centrally adjudicated by masked reviewers, there were no strokes but 6 transient ischemic attacks (3 in each arm). One child (transfusion arm) was withdrawn per the TCD alert algorithm after developing on-study TCD velocities 〉 240 cm/sec. Exit brain MRI/MRA exams documented no new parenchymal abnormalities but one child (transfusion arm) developed new vasculopathy. Sickle cell related serious adverse events were more common in the hydroxyurea arm than the transfusion arm (23 to 15), but none was related to study treatment or study procedures. Iron overload improved more in the hydroxyurea arm than in the transfusion arm, with a greater average change in serum ferritin (-1085 compared to -38 ng/mL, p 〈 0.001) and LIC (average -1.9 compared to +2.4 mg/g dry weight liver, p=0.001). In the multicenter Phase III TWiTCH trial, which treated children with SCA and abnormal TCD velocities but without severe MRA vasculopathy, hydroxyurea at MTD was non-inferior and possibly superior to chronic transfusions for maintaining TCD velocities. Serial phlebotomy effectively managed iron overload. Hydroxyurea may represent an effective alternative to indefinite transfusions for the prevention of primary stroke in this high risk population. Disclosures Ware: Eli Lilly: Other: DSMB membership; Bayer Pharmaceuticals: Consultancy; Bristol Myers Squibb: Research Funding; Biomedomics: Research Funding. Off Label Use: Hydroxyurea for children with SCA. Owen:Novartis: Speakers Bureau. Rogers:BioRad Labs: Consultancy; Apopharma: Consultancy; Baxter: Consultancy; Glaxo Smith Kline: Consultancy. Kwiatkowski:Shire Pharmaceuticals and Sideris Pharmaceuticals: Consultancy; Sideris Pharmaceuticals: Consultancy; Novartis: Research Funding; ISIS: Membership on an entity's Board of Directors or advisory committees. Heeney:Sancillio: Consultancy; Eli Lilly: Research Funding. Nottage:Janssen Pharmaceuticals: Employment. Cohen:Novartis: Consultancy; ApoPharma: Other: DSMB member.

Abstract: Background: Chimeric antigen receptor T-cell (CAR-T) therapy is an effective strategy for patients (pts) with B-cell non-Hodgkin lymphomas (B-NHLs). However, long-term remissions are only observed in ~40% of pts with large cell lymphomas (LCL) treated with FDA-approved CD19-targeted products and there is currently no approved CAR-T for other histologies other than mantle cell lymphoma (MCL). CD20 is a proven therapeutic target for B-NHL, supported by previously approved naked and radiolabeled anti-CD20 antibodies and promising results from bispecific antibodies. CD20-targeted CAR-T is another potential adoptive immunotherapy option that could be utilized in combination or in sequence with CD19 CAR-T. We present interim results of our ongoing phase I/II clinical trial investigating safety and efficacy CD20 CAR-T for high-risk B-NHLs (NCT03277729). Methods: MB-106 is a fully human third-generation CD20-targeted CAR-T with both 4-1BB and CD28 costimulatory domains. We use a continuous reassessment method dose escalation design to find the maximally tolerated dose. Lymphodepletion (LD) consists of cyclophosphamide (Cy) ± fludarabine (Flu). CAR-T cells are administered at one of 4 dose levels (DL): DL1: 3.3 x 105, DL2: 1 x106, DL3: 3.3x106, DL4: 1x107 CAR T cells/kg. CAR-T is infused in the outpatient setting except for the first pts of each dose cohort (overnight observation). Pts with CD20+ B-NHL are eligible, including but not limited to LCL, follicular lymphoma (FL)/indolent histologies and MCL. Prior treatment with CD19 CAR-T is permitted. Treatment response is assessed on day 28 using 2014 Lugano criteria. Cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) were graded per 2014 Lee criteria and the ASTCT consensus grading, respectively. Results: Between 2018-2020, 12 pts underwent leukapheresis (LA) and 11 (92%) were treated on the protocol. The first 7 pts (3 FL, 3 MCL, 1 hairy cell variant) were treated using the original cell manufacturing method with separate culturing of CD4+ and CD8+ cells ("original process"). First 4 of those 7 pts (2 treated at DL1 and 2 at DL2) only received Cy for LD and the other 3 (all at DL1) were treated after LD with Cy-Flu. There was no evidence of ICANS in those 7 pts and only 1 pt developed CRS (grade 3 - unexplained elevated alkaline phosphatase (ALP) in the setting of fever). Responses at 4 weeks for pts treated with the "original process" included stable disease (SD) in 4 and progressive disease (PD) in 3 pts. Given the challenges in meeting the protocol requirements for CD4+ and CD8+ specific doses, poor CAR-T expansion, and lack of clinical responses, enrollment was placed on a hold and cell manufacturing process underwent a major revision which included changing to a combined culture of CD4+ and CD8+ cells, among other modifications ("modified process"). Since December 2019 enrollment was reinitiated at DL1 under the "modified process." Four pts were treated after LD with Cy-Flu at DL1 (2 FL) and dose level 2 (1 FL and 1 MCL) (details in Table 1). Target cell doses were achieved in all 4 patients and treatment was tolerated with no occurrence of CRS (any grade) or ICANS (any grade). Responses were observed at both dose levels and included complete remissions (CRs) in 2 FL pts (1 treated at DL1 and 1 at DL2), partial remission (PR) in a MCL pt treated at DL2 and PD in a FL pt who was treated at DL1. Robust CAR-T expansion was seen in 3 of the 4 patients, with peak blood levels of CAR+ T cells of 161, 5.5, and 401 CAR+ cells/µl, corresponding to 80%, 23%, and 72% of all CD8+ cells. Combining all 11 pts treated under the "original" and "modified" processes, no dose-limiting toxicity (DLT) was observed. Grade ≥ 3 toxicities included: anemia (n=4, 36%), lymphopenia (n=3,27%), febrile neutropenia (n=2, 18%), hypertension (n=1, 9%) , hypotension (n=1, 9%), thromboembolic event (n=1, 9%), neutropenia (n=1, 9%), elevated ALP (n=1, 9%), pneumonia (n=1, 9%), bacteremia (n=1, 9%), hyperglycemia (n=1, 9%), pleural effusion (n=1, 9%) and generalized pain (n=1, 9%). Conclusion: Early results of our ongoing study of CD20 CAR-T for high-risk NHLs suggests an extremely favorable safety profile (no CRS or ICANS of any grades) with the modified manufacturing process. There is also evidence of clinical activity even at low dose levels with observed CRs at DLs 1 and 2. Enrollment at higher DLs is currently ongoing and the data will be updated at the time of presentation. Disclosures Shadman: Abbvie, Genentech, Astra Zeneca, Sound Biologics , Pharmacyclics, Verastem, ADC therapeutics, Beigene, Cellectar, BMS, Morphosys and Atara Biotherapeutics: Consultancy; Mustang Bio, Celgene, Pharmacyclics, Gilead, Genentech, Abbvie, TG therapeutics, Beigene, Astra Zeneca, Sunesis, Beigene: Research Funding. Yeung:OBI;Pfizer: Research Funding; Adaptive Biotechnology;Eli Lilly;Merck: Consultancy. Ramachandran:Mustang Bio: Current Employment. Graf:TG Therapeutics: Research Funding; BeiGene: Research Funding; MorphoSys: Consultancy; Acerta Pharma: Research Funding. Gopal:IgM bio, BMS, merck: Research Funding; Seattle Genetics; Janssen; IMab Bio; TG Therapeutics; Astra Zeneca; Merck; Gilead; ADC Therapeutics; Nurix; TG therapeutics, Cellectar; Actinium: Consultancy; imab bio, takeda,astrazeneca,gilead: Research Funding; Seattle Genetics; Janssen; Takeda; IgM Bio; IMab Bio; BMS; Astra Zeneca; Merck; Gilead: Research Funding. Gauthier:JMP, Eusapharma, Multerra Bio: Honoraria. Cassaday:Pfizer: Honoraria, Research Funding; Seattle Genetics: Current Employment, Current equity holder in publicly-traded company; Vanda Pharmaceuticals: Research Funding; Kite/Gilead: Consultancy, Research Funding; Merck: Research Funding; Amgen: Consultancy, Research Funding. Kiem:Magenta Therapeutics, CSL,Homology Medicines, Vor Biopharma , Enochian, Umoja, Rocket Pharma: Consultancy. Turtle:Novartis: Consultancy; Myeloid Therapeutics: Current equity holder in private company, Honoraria, Membership on an entity's Board of Directors or advisory committees; Allogene: Consultancy; PACT Pharma: Consultancy; Arsenal Bio: Current equity holder in private company, Honoraria, Membership on an entity's Board of Directors or advisory committees; Caribou Biosciences: Current equity holder in private company, Honoraria, Membership on an entity's Board of Directors or advisory committees; Eureka Therapeutics: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; Precision Biosciences: Current equity holder in publicly-traded company, Honoraria, Membership on an entity's Board of Directors or advisory committees; Physician Education Resource: Consultancy; AstraZeneca: Consultancy, Research Funding; Nektar Therapeutics: Consultancy, Research Funding; Juno/BMS: Patents & Royalties, Research Funding; Century Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; T-CURX: Membership on an entity's Board of Directors or advisory committees; Humanigen: Consultancy; Kite/Gilead: Consultancy. Maloney:Pharmacyclics: Consultancy, Honoraria; Juno Therapeutics: Consultancy, Honoraria, Patents & Royalties: Patents are pending, but not issued, licensed, no royalties, no licensees., Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Kite, a Gilead Company: Consultancy, Honoraria, Research Funding; Gilead Sciences: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; MorphoSys: Consultancy, Honoraria; Bioline Rx: Consultancy, Honoraria; A2 Biotherapeutics: Consultancy, Current equity holder in publicly-traded company, Honoraria; Genentech: Consultancy, Honoraria. Till:Mustang: Patents & Royalties, Research Funding.

Abstract: Relapse following chimeric antigen receptor (CAR) T-cell therapy directed against CD19 for relapsed/refractory B-acute lymphoblastic leukemia (r/r B-ALL) remains a significant challenge. Three main patterns of relapse predominate: CD19 positive (CD19pos) relapse, CD19 negative (CD19neg) relapse, and lineage switch (LS). Development and validation of risk factors that predict relapse phenotype could help define potential pre- or post-CAR T-cell infusion interventions aimed at decreasing relapse. Our group sought to extensively characterize preinfusion risk factors associated with the development of each relapse pattern via a multicenter, retrospective review of children and young adults with r/r B-ALL treated with a murine-based CD19-CAR construct. Of 420 patients treated with CAR, 166 (39.5%) relapsed, including 83 (50%) CD19pos, 68 (41%) CD19neg, and 12 (7.2%) LS relapses. A greater cumulative number of prior complete remissions was associated with CD19pos relapses, whereas high preinfusion disease burden, prior blinatumomab nonresponse, older age, and 4-1BB CAR construct were associated with CD19neg relapses. The presence of a KMT2A rearrangement was the only preinfusion risk factor associated with LS. The median overall survival following a post-CAR relapse was 11.9 months (95% CI, 9-17) and was particularly dismal in patients experiencing an LS, with no long-term survivors following this pattern of relapse. Given the poor outcomes for those with post-CAR relapse, study of relapse prevention strategies, such as consolidative hematopoietic stem cell transplantation, is critical and warrants further investigation on prospective clinical trials.

Abstract: Purpose: Previous studies of patient-physician communication have noted that patients (pts) want to know “as much information as possible” about their diseases, but very little is known about successful ways to communicate this information. Patients and Methods: We report interim results of an ongoing, longitudinal study of patient-physician communication among people with hematologic malignancies. 83 pts seeing 15 physicians were studied at the Dana-Farber Cancer Institute (DFCI), Boston, MA between 9/02-9/03. After informed consent, subjects were interviewed qualitatively and quantitatively prior to their consultations, the consultation was audiotaped, and pts were interviewed between 1–10 days after their consultations. 83/176 (47%) of invited patients participated. Results: Interim results from the pre-consultation and post-consultation interviews for evaluable pts (n=72) are presented. Overall, the population was well-educated (53% college graduates), married (74%), White (81%), and reported high social support and relatively little anxiety and depression. The median age was 58 yrs (range 20–80 yrs), 46% were female, and the median time from diagnosis to study was 69 days (range 7–1512 d). The primary diagnoses were non-Hodgkin’s lymphoma (n=22, 31%) and multiple myeloma (n=21, 29%). Most wanted to be an equal partner in decision making (41%) or take primary responsibility for the decision (36%). Almost everyone wanted to discuss treatment options, treatment goals, and physician treatment recommendations (96–100%), but fewer wanted to discuss average patient survival (86%), likelihood of treatment success (70%), likelihood of cure (60%) or clinical trials (49%). 70% wanted prognostic information in percentages and 64% wanted to hear about previous pts, while fewer desired fractions (43%) or qualitative expressions of probability (44%). When asked to estimate prognosis (chance of cure and life expectancy) before the consultation, pts were much more optimistic compared to their physicians. After the consultation, most pts’ prognostic estimates were unchanged although a few (14–24%) became more optimistic and 7–19% became less optimistic. Most pts were satisfied with their consultations and “very likely” to recommend their physicians to other pts (88%). Pts were completely (69%) or somewhat (28%) satisfied with the amount of information they were given. Most reported the same or improved depression, anxiety and hope after their consultations. Conclusions: Patients in our study are interested in most but not all information about their diseases. In particular, they want information about treatment options and recommendations, but less information about the likely course of the disease. While physicians appear to be communicating with patients in ways that result in high degrees of satisfaction, maintain hope, and do not diminish patients’ sense of depression or anxiety, patients are retaining their overoptimistic prognostic expectations after their consultations.

Abstract: Physician-patient communication encompasses the verbal and nonverbal interactions that form the basis for the doctor-patient relationship. A growing body of research and guidelines development acknowledges that physicians do not have to be born with excellent communication skills, but rather can learn them as they practice the other aspects of medicine. Improvement in physician-patient communication can result in better patient care and help patients adapt to illness and treatment. In addition, knowledge of communication strategies may decrease stress on physicians because delivering bad news, dealing with patients’ emotions, and sharing decision making, particularly around issues of informed consent or when medical information is extremely complex, have been recognized by physicians as communication challenges. This paper will provide an overview of research aimed at improving patient outcome through better physician-patient communication and discuss guidelines and practical suggestions immediately applicable to clinical practice.