Citations

Primary effusion lymphoma (PEL) is a rare, aggressive B-cell lymphoma that usually localizes to serous body cavities to subsequently form effusions in the absence of a discrete mass. Although some tumors can develop in extracavitary locations, the areas most often affected include the peritoneum, pleural space, and the pericardium. PEL is associated with the presence of human herpesvirus 8 (HHV8), also called the Kaposi sarcoma-associated herpesvirus (KSHV), with some variability in transformation potential suggested by frequent coinfection with the Epstein-Barr virus (EBV) (~80%), although the nature of the oncogenesis is unclear. Most patients suffering with this disease are to some degree immunocompromised (e.g., Human immunodeficiency virus (HIV) infection or post-solid organ transplantation) and, even with aggressive treatment, prognosis remains poor. There is no definitive guideline for the treatment of PEL, although CHOP-like regimens (cyclophosphamide, doxorubicin, vincristine, and prednisone) are frequently prescribed and, given the rarity of this disease, therapeutic focus is being redirected to personalized and targeted approaches in the experimental realm. Current clinical trials include the combination of lenalidomide and rituximab into the EPOCH regimen and the treatment of individuals with relapsed/refractory EBV-associated disease with tabelecleucel.

Abstract Introduction. About 60% of patients with large B-cell lymphoma (LBCL) relapse after standard of care (SOC) anti-CD19 autologous chimeric antigen receptor (CAR) T-cell therapy, CD19 downregulation representing a major mechanism of resistance. Therefore, agents able to target B-cell antigens other than CD19 could be clinically effective for these patients. Polatuzumab vedotin (PV) is an antibody-drug conjugate targeting CD79b, and approved by the FDA in combination with bendamustine and rituximab for patients with relapsed or refractory (r/r) LBCL. Patients who relapsed after CAR T-cell therapy were not included in the registration study, and reports of PV use after CAR T-cells in real world practice are very limited. Methods. This is a multi-center retrospective analysis of patients with LBCL who relapsed after SOC CAR T-cell therapy and subsequently received SOC PV with or without rituximab and bendamustine between 07/2019 and 04/2021. PV was given at the standard dose of 1.8 mg/kg IV every 3 weeks in all patients (except for one patient, who received 1.4 mg/Kg). Response to treatment and progression were defined according to 2014 Lugano criteria. Survival curves were calculated using Kaplan-Meier estimates, and were compared between subgroups using the log-rank test. Cox regression was used for multivariate analysis (MVA). Results. Fifty-four patients were included in the study: median age was 59 (range, 22-79 years), 38 (70%) were male, and 30 (56%) had an internal prognostic index score > 3. Median number of systemic therapies before CAR T-cell therapy was 2 (range, 2-6), 16 (30%) patients previously had autologous stem cell transplant (SCT), and 2 (4%) had allogeneic SCT. Sixteen (30%) patients were primary refractory to CAR T-cell therapy, and median time from CAR T-cell therapy to PV was 5 months (range, 1-40 months). CD19 status at time of relapse after CAR T-cell therapy was assessed by immunohistochemistry and/or flow cytometry in 41 patients, and positive in 34 (83%); CD79b status was assessed in 14 patients, and positive in all cases (100%). Thirty-two (59%) patients received PV-based therapy immediately after CAR T cell therapy, while 22 (41%) had intervening treatments (median 1, range 1-5). At time of PV initiation, median absolute neutrophil count was 2.9 (range 0.5-19 X10 9/L), median platelet count was 87 X10 9/L (range 15-437 X10 9/L), median serum creatinine was 0.9 mg/dL (range 0.4-22 mg/dL), and 44 (81%) patients had elevated serum lactate dehydrogenase (LDH). The median number of PV cycles was 2 (range, 1-16): PV was combined with rituximab in 51 (94%) patients, and administered with bendamustine in 33 (61%). A response was achieved in 24 (45%) patients, including complete remission (CR) in 8 (14%) patients and partial remission in 16 (30%)(Figure A), with a median duration of response of 11 weeks (95%CI, 5-17 weeks). No significant association between baseline characteristics and response was observed. To date, 49 (91%) patients stopped PV: 38 (70%) due to progression, 7 (13%) because of CR/patient decision, 3 (6%) to proceed to allogeneic SCT, and 1 (2%) to proceed to an immunotherapy clinical trial (despite absence of progression). No patients stopped therapy because of toxicity. After a median follow up of 45 weeks (95% CI, 20-70 weeks), 44 (81%) patients progressed/died, and median PFS was 9 weeks (95% CI, 4-14 weeks). To date, 34 (63%) died, and median OS was 16 weeks (95% CI, 13-19 weeks)(Figure B). Causes of death included progression in 31 patients and transplant-related complications in 3. On univariate analysis, a shorter median progression-free survival (PFS) was observed for patients with bone marrow (BM) involvement (3 vs 10 weeks, p=0.002), prior central nervous system involvement (4 vs 10 weeks, p=0.02), and elevated LDH (6 months vs not reached, p=0.004). On MVA, the association was maintained only for BM involvement (hazard ratio [HR] 4.8; 95% confidence interval [CI] 1.6-12.5, p=0.004) and elevated LDH (HR 5; 1.4-16.7, p=0.01)(Figure C). Discussion. PV is safe and effective, but has short duration of response in r/r LBCL after anti-CD19 CAR T-cell therapy, except for patients with normal LDH. Studies aimed at better characterizing intrinsic mechanism of resistance, including upregulation of BCL2 family proteins, to favor the development of more effective PV-based combination strategies for these patients, are warranted. Figure 1 Figure 1. Disclosures Crombie: Roche: Research Funding; Merck: Research Funding; Abbvie: Research Funding; Bayer: Research Funding; Karyopharm: Consultancy; Incyte: Consultancy. Kamdar: Celgene (BMS): Consultancy; Adaptive Biotechnologies: Consultancy; Genentech: Research Funding; Kite: Consultancy; AstraZeneca: Consultancy; ADC Therapeutics: Consultancy; Genetech: Other; TG Therapeutics: Research Funding; SeaGen: Speakers Bureau; Celgene: Other; KaryoPharm: Consultancy; AbbVie: Consultancy. Hess: ADC Therapeutics: Consultancy; BMS: Speakers Bureau. Neelapu: Takeda Pharmaceuticals and related to cell therapy: Patents & Royalties; Kite, a Gilead Company, Bristol Myers Squibb, Merck, Poseida, Cellectis, Celgene, Karus Therapeutics, Unum Therapeutics (Cogent Biosciences), Allogene, Precision BioSciences, Acerta and Adicet Bio: Research Funding; Kite, a Gilead Company, Merck, Bristol Myers Squibb, Novartis, Celgene, Pfizer, Allogene Therapeutics, Cell Medica/Kuur, Incyte, Precision Biosciences, Legend Biotech, Adicet Bio, Calibr, Unum Therapeutics and Bluebird Bio: Honoraria; Kite, a Gilead Company, Merck, Bristol Myers Squibb, Novartis, Celgene, Pfizer, Allogene, Kuur, Incyte, Precision BioSciences, Legend, Adicet Bio, Calibr, and Unum Therapeutics: Other: personal fees. Lin: Novartis: Consultancy; Bluebird Bio: Consultancy, Research Funding; Juno: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Gamida Cell: Consultancy; Sorrento: Consultancy; Legend: Consultancy; Takeda: Research Funding; Merck: Research Funding; Vineti: Consultancy. Strati: Astrazeneca-Acerta: Research Funding; Roche-Genentech: Consultancy.

Abstract BACKGROUND: Mantle cell lymphoma (MCL) is a B-cell non-Hodgkin lymphoma with variable clinical outcomes. Commonly used risk stratification tools (Ki67 IHC, MIPI) in newly diagnosed MCL are not frequently used when selecting therapy, resulting in treatment choice being dictated by age and co-morbidities rather than disease biology. The MCL35 risk score was developed as a more reliable measure of proliferation and has been shown to be prognostic and can risk stratify younger transplant eligible MCL patients into three groups with significantly different overall survival (OS; Scott et al. 2017; Holte et al. 2018) but has not been evaluated in older transplant ineligible patients. We report results evaluating the prognostic value of the MCL35 assay in older MCL patients (≥65) treated with frontline bendamustine/rituximab (BR). METHODS: Archived tissue samples from 119 patients age ≥65 years treated with BR from collaborating Lymphoma/Leukemia Molecular Profiling Project (LLMPP) sites and the LEO/MER cohort were collected and analyzed using the MCL35 assay and stratified into three distinct risk groups (low, standard, and high risk). Association between MCL35 proliferation scores and OS were estimated by the Kaplan-Meier method and hazard ratios were calculated. Associations between Ki67, s-MIPI, p53 IHC status, morphology and OS were also evaluated. RESULTS: The MCL35 assay was run on tissue samples from 119 patients. Median patient age was 74 (range 65-93) and 69.5% were male. Ki67 was <30% in 29 patients (24%) and ≥30% in 90 patients (76%). Simplified MIPI (s-MIPI) score was 0-3 in 21 patients (24%), 4-5 in 42 patients (48%) and ≥6 in 25 patients (28%). Thirty-one did not have sufficient data to calculate a s-MIPI score. MCL35 was low risk in 51 patients (43%), standard risk in 39 patients (33%) and high risk in 29 patients (24%). Eleven patients had blastic morphology, 7 had pleomorphic morphology and the remainder were classic morphology (n=56). Of 57 samples with p53 IHC staining 7 (12.3%) were positive. At a median follow up of 33.4 months, 82 patients were alive and 35 had died. Patients with high risk MCL35 score had inferior OS compared to low risk (HR 2.27, 95% CI: 1.03-5.00; p=0.042) while standard risk was not statistically significant compared to low risk (HR 0.87, 95% CI: 0.37-2.0; p=0.740)(Figure 1). Ki67 IHC using a cutoff of ≥ 30% and 10%-29% was not significantly associated with OS compared to Ki67 <10% ( Ki67 ≥ 30% vs. Ki67 < 10%, HR 0.87, 95% CI: 0.12-6.41; p=0.892, Ki67 ≥ 10%-29% vs. Ki67 < 10%, HR 0.32, 95% CI: 0.04-2.83; p=0.303), however high s-MIPI score (≥6) (s-MIPI ≥6 vs. s-MIPI 0-3, HR 3.86, 95% CI 1.20-12.5; p=0.024) and positive p53 IHC (HR: 9.51, 3.26-27.7; p <0.001) were both associated with poor OS. Eighteen cases were blastic/pleomorphic by morphology, 12 of which were in the high-risk group by MCL35, and this subset also had worse survival than classic MCL (p=0.0052). CONCLUSIONS: These results suggest high risk MCL35 score is a prognostic biomarker of poor OS in patients >65 with MCL treated with BR. Conversely, Ki67 was not significantly associated with OS in these patients. Additional clinical validation using a larger sample size from the E1411 study is planned. If similar results are found, the MCL35 assay in combination with s-MIPI and p53 status may have utility in stratifying patients into risk adapted treatment arms in future prospective clinical trial designs. Figure 1 Figure 1. Disclosures Maurer: BMS: Research Funding; Genentech: Research Funding; Morphosys: Membership on an entity's Board of Directors or advisory committees, Research Funding; Kite Pharma: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Nanostring: Research Funding. Villa: Janssen: Honoraria; Gilead: Honoraria; AstraZeneca: Honoraria; AbbVie: Honoraria; Seattle Genetics: Honoraria; Celgene: Honoraria; Lundbeck: Honoraria; Roche: Honoraria; NanoString Technologies: Honoraria. Habermann: Seagen: Other: Data Monitoring Committee; Incyte: Other: Scientific Advisory Board; Tess Therapeutics: Other: Data Monitoring Committee; Morphosys: Other: Scientific Advisory Board; Loxo Oncology: Other: Scientific Advisory Board; Eli Lilly & Co.,: Other: Scientific Advisor. Cohen: Janssen, Adicet, Astra Zeneca, Genentech, Aptitude Health, Cellectar, Kite/Gilead, Loxo, BeiGene, Adaptive: Consultancy; Genentech, BMS/Celgene, LAM, BioINvent, LOXO, Astra Zeneca, Novartis, M2Gen, Takeda: Research Funding. Hill: Celgene (BMS): Consultancy, Honoraria, Research Funding; Epizyme: Consultancy, Honoraria; Gentenech: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria; Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel Support, Research Funding; Karyopharm: Consultancy, Honoraria, Research Funding; AstraZenica: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Beigene: Consultancy, Honoraria, Research Funding; Incyte/Morphysis: Consultancy, Honoraria, Research Funding. Raess: Scopio Labs: Research Funding. Scott: Celgene: Consultancy; NanoString Technologies: Patents & Royalties: Patent describing measuring the proliferation signature in MCL using gene expression profiling.; BC Cancer: Patents & Royalties: Patent describing assigning DLBCL COO by gene expression profiling--licensed to NanoString Technologies. Patent describing measuring the proliferation signature in MCL using gene expression profiling. ; Rich/Genentech: Research Funding; Janssen: Consultancy, Research Funding; Incyte: Consultancy; Abbvie: Consultancy; AstraZeneca: Consultancy. Rimsza: NanoString Technologies: Other: Fee-for-service contract.

Abstract Introduction: Novel genetic classifications of diffuse large B-cell lymphoma (DLBCL) highlight the molecular complexity beyond cell of origin and provide new therapeutic implications. Next generation trials may incorporate novel agents for different genetic subtypes based on the pathogenesis mechanisms. For example, with the LymphGen classification, the MCD, BN2, ST2, and EZB subtypes are predicted to be susceptive to PI3K/mTOR targeting (Wright 2020). However, PI3K inhibitors have not been tested in the frontline, although data on the mTOR inhibitor everolimus were encouraging (Alliance 1085). We launched a phase 1/1b trial (NCT04323956) to investigate the feasibility of combining a novel PI3K inhibitor parsaclisib with standard R-CHOP immunochemotherapy and to seek an efficacy signal. Methods: Adult patients with newly diagnosed DLBCL were eligible if any of the following was present: 1) non-GCB subtype per the Hans algorithm; 2) expression of either Myc (≥40%) or Bcl2 (≥50%) by immunohistochemistry; or 3) MYC rearrangement by FISH. High grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements, regardless of morphology, was also eligible. All patients received parsaclisib plus R-CHOP. Phase 1 followed a 3+3 design and the primary endpoint was maximum tolerated dose (MTD) of parsaclisib. Dose levels tested were level 1 (20 mg QD, d1-10; starting level) and level 2 (20 mg QD, d1-14). MTD was defined as the dose level below the lowest dose that induced dose limiting toxicity (DLT) in at least one-third of patients. The primary endpoint in phase 1b is complete response (CR) rate by PET. Results: From July 2020 to June 2021, 15 patients were enrolled, 9 in phase 1 and 6 in phase 1b. The median age at diagnosis was 56 years (range 20-79), and 7 (47%) were female. One patient (7%) had ECOG PS ≥2, 7 (47%) had elevated LDH, 7 (47%) had >1 extranodal site, 13 (87%) had stage III/IV, and 7 (47%) had high-intermediate or high risk International Prognostic Index. Pathology was DLBCL in 13 patients (2 with concurrent follicular lymphoma) and high grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements in 2 patients. Four (27%) had non-GCB subtype, 7 (47%) had Myc or Bcl2 single expression, 8 (53%) had Myc/Bcl2 double expression, and 5 (33%) had MYC rearrangement (2 with concurrent BCL2 and/or BCL6 rearrangements). In phase 1, 3 patients were enrolled at dose level 1 and 6 patients were enrolled at dose level 2. No DLT was observed. Therefore, MTD was not reached, and dose level 2 was selected for phase 1b dose expansion. Six patients were enrolled in phase 1b to date. At the data cutoff date of 7/22/2021, 8 patients completed all 6 cycles of treatment, 1 competed 5 cycles, 3 completed 3 cycles, 2 completed 2 cycles, and 1 completed 1 cycle. Treatment-related adverse events (AE) are summarized in Table 1. The most common hematological AE included lymphopenia (60%), anemia (53%), neutropenia (53%), and thrombocytopenia (27%), and the most common non-hematological AE included nausea (67%), alopecia (40%), constipation (33%), fatigue (33%), dyspepsia (20%), and peripheral sensory neuropathy (20%). The most common grade 3 or 4 AE included lymphopenia (47%), neutropenia (33%), and anemia (13%). One 80-year-old female required parsaclisib dose reduction in cycle 3 and subsequent parsaclisib discontinuation as well as cyclophosphamide and doxorubicin dose reductions due to febrile neutropenia (no source of infection was identified). No other patients required dose reductions. The median follow-up was 3.7 months (range 0.8-10.7). Thirteen patients were evaluable for interim response by PET. The objective response rate was 92%, with 8 (62%) CR and 4 (31%) partial response (PR). One (8%) patient progressed before cycle 2 following a transient clinical response (shrinking palpable mass). Among those who achieved an objective response at interim, 7 patients were evaluable for end of treatment response and all 7 maintained a response, with 6 (86%) CR and 1 (14%) PR. Conclusions: Parsaclisib and R-CHOP combination therapy was generally well tolerated, with no DLT observed in phase 1 and no major safety concerns in both phase 1 and the ongoing phase 1b expansion. The preliminary efficacy signal of objective response appears encouraging in a small cohort of high risk patients. Parsaclisib plus R-CHOP can be an experimental arm for future frontline DLBCL trials investigating genetic subtype-driven novel therapies. Figure 1 Figure 1. Disclosures Wang: Incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding; InnoCare: Research Funding; LOXO Oncology: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; Genentech: Research Funding; MorphoSys: Research Funding; Eli Lilly: Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees. King: Celgene/BMS: Research Funding. Ansell: Bristol Myers Squibb, ADC Therapeutics, Seattle Genetics, Regeneron, Affimed, AI Therapeutics, Pfizer, Trillium and Takeda: Research Funding. Tun: Gossamer Bio, Acrotech: Consultancy; Mundipharma, Celgene, BMS, Acrotech, TG therapeutics, Curis, DTRM: Research Funding. Habermann: Seagen: Other: Data Monitoring Committee; Incyte: Other: Scientific Advisory Board; Tess Therapeutics: Other: Data Monitoring Committee; Morphosys: Other: Scientific Advisory Board; Loxo Oncology: Other: Scientific Advisory Board; Eli Lilly & Co.,: Other: Scientific Advisor. Witzig: Karyopharm Therapeutics, Celgene/BMS, Incyte, Epizyme: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene/BMS, Acerta Pharma, Kura Oncology, Acrotech Biopharma, Karyopharm Therapeutics: Research Funding. Nowakowski: Celgene, NanoString Technologies, MorphoSys: Research Funding; Celgene, MorphoSys, Genentech, Selvita, Debiopharm Group, Kite/Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees. OffLabel Disclosure: Parsaclisib is an investigational agent used in this clinical trial.

Abstract Introduction: Novel therapeutic agents such as immune checkpoint inhibitor (ICI) and brentuximab vedotin (BV) are active in classic Hodgkin lymphoma (cHL), including in patients that relapse after autologous stem cell transplant (ASCT). However, optimal management strategy is unclear for patients with relapsed or refractory (RR) cHL post-ASCT. The aim of the study is to determine the impact of novel agents relative to conventional therapy and allogeneic stem cell transplant (allo-SCT) on survival outcomes of patients with cHL who relapsed after ASCT. Methods: Patients with RR cHL who underwent ASCT between 06/1993 and 10/2017 at 3 Mayo Clinic sites were included. Clinical characteristics, treatment information, and outcome data were abstracted. For patients who relapsed after ASCT, the post-relapse progression free survival (PFS) and overall survival (OS) were analyzed using the Kaplan-Meier method and Cox proportional hazards models. Statistical analyses were done in JMP v15.2.1 and EZR v1.54. Results: A total of 332 patients with RR cHL who underwent salvage therapy and ASCT were identified. After a median post-ASCT follow-up of 8.6 years (range 6.8-9.7), 136 (41%) patients had a relapse or disease progression after ASCT. Patient characteristics of the 136 cases are summarized in the Table. The median age at post-ASCT relapse was 34 years (range 20-73), and 77 (57%) were male. 59 (43%) relapsed within 6 months and 77 (57%) relapsed after 6 months following ASCT. 59 (45%) had an extranodal site involvement at relapse. 14 (10%) had therapy with ICI or BV as salvage therapy prior to ASCT or maintenance therapy post-ASCT. The median post-relapse PFS and OS was 0.8 (95% CI 0.6-1.1) and 3.2 years (95% CI 2.2-5.5) years, respectively. Compared to patients who relapse after 6 months, patients who relapsed within 6 months of ASCT had worse post-relapse PFS (median 0.5 [0.3-0.7] vs 1.3 [0.9-1.9] years, p=0.0003) and OS (median 1.3 [0.5-2.2] vs 6.4 [3.7-10.4] years, p=0.0003). Extranodal site involvement at relapse was not associated with post-relapse PFS (median 0.7 [0.5-1.2] vs 0.9 [0.6-1.3] years, p=0.28) but was associated with worse post-relapse OS (median 2.7 [1.5-4.2] vs 6.4 [2.6-NA] years, p=0.006). Prior therapy with ICI or BV was not associated with post-relapse PFS (median 0.6 [0.3-NA] vs 0.8 [0.6-1.1] year, p=0.8) and OS (median NR [1.0-NA] vs 3.2 [2.2-5.5] years, p=0.5). After post-ASCT relapse, the median lines of subsequent therapy were 2 (range 1-12). For first post-ASCT salvage therapy, novel agents (ICI or BV), compared to other therapies, were associated with superior post-relapse PFS (median 1.7 [0.7-3.6] vs 0.7 [0.5-1.0] years, p=0.004) and OS (median 7.6 [4.7-NA] vs 3.2 [2.2-5.6], p=0.02). Allo-SCT following first post-ASCT relapse (n=9) was not associated with improvement in post-relapse PFS (median 2.2 years [0.3-NA] vs 0.8 [0.6-1.1] years, p=0.1) or OS (median NR [0.5-NA] vs 5.1 [3.2-7.3] years, p=0.7). Patients who received ICI or BV at any point post-ASCT relapse had significantly better post-relapse OS (median 7.6 [4.3-16.7] vs 2.2 [1.4-3.7] years, p=0.004) compared to those who never received any novel agent (Figure 1A). In contrast, allo-SCT at any point post-ASCT relapse (n=27) did not improve post-relapse OS (median 5.6 [2.7-NA] vs 4.7 [2.7-7.3] years, p=0.3) (Figure 1B). In multivariate Cox regression models adjusted for age and sex, exposure to ICI and/or BV was associated with superior post-relapse OS (HR 0.5, 95% CI 0.3-0.8, p=0.007); however, allo-SCT was not associated with improvement in post-relapse OS (HR 0.8, 95% CI 0.4-1.5, p=0.5). Conclusions: Patients relapsing within 6 months of ASCT and those with extranodal involvement at relapse had inferior OS after post-ASCT relapse. Prior therapy with novel agents did not impact post-relapse survival outcomes. In the setting of post-ASCT relapse, novel therapeutic agents significantly improved survival outcomes while allo-SCT did not. Future multicenter studies are needed to explore the role of novel agents and allo-SCT in patients with RR cHL post-ASCT relapse. Figure 1 Figure 1. Disclosures Wang: Eli Lilly: Membership on an entity's Board of Directors or advisory committees; InnoCare: Research Funding; MorphoSys: Research Funding; Genentech: Research Funding; Novartis: Research Funding; LOXO Oncology: Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees. Paludo: Karyopharm: Research Funding. Tun: Gossamer Bio, Acrotech: Consultancy; Mundipharma, Celgene, BMS, Acrotech, TG therapeutics, Curis, DTRM: Research Funding. Cerhan: Regeneron Genetics Center: Other: Research Collaboration; Genentech: Research Funding; Celgene/BMS: Other: Connect Lymphoma Scientific Steering Committee, Research Funding; NanoString: Research Funding. Habermann: Tess Therapeutics: Other: Data Monitoring Committee; Morphosys: Other: Scientific Advisory Board; Incyte: Other: Scientific Advisory Board; Seagen: Other: Data Monitoring Committee; Loxo Oncology: Other: Scientific Advisory Board; Eli Lilly & Co.,: Other: Scientific Advisor. Witzig: Karyopharm Therapeutics, Celgene/BMS, Incyte, Epizyme: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene/BMS, Acerta Pharma, Kura Oncology, Acrotech Biopharma, Karyopharm Therapeutics: Research Funding. Nowakowski: Celgene, MorphoSys, Genentech, Selvita, Debiopharm Group, Kite/Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene, NanoString Technologies, MorphoSys: Research Funding. Ansell: Bristol Myers Squibb, ADC Therapeutics, Seattle Genetics, Regeneron, Affimed, AI Therapeutics, Pfizer, Trillium and Takeda: Research Funding.

Abstract Background :COVID-19 adversely affects individuals with cancer. Several studies have found that seroconversion rates among patients with hematologic malignancies are suboptimal when compared to patients without cancer. Among patients with hematologic malignancies, seroconversion rates also appear to be influenced by recent treatment and the type of treatment they have received. Patients with non-Hodgkin lymphoma (NHL) and multiple myeloma (MM) are immunocompromised due to impaired humoral and cellular immunity in addition to prescribed immunosuppressive therapy. Chimeric antigen receptor T-cell (CAR T) therapy is now widely used for NHL and MM, but little is known about seroconversion rates after COVID-19 vaccination among these populations. Current national guidelines recommend COVID-19 vaccination to be offered to CAR T recipients as early as three months thereafter. We retrospectively evaluated SARS-CoV-2 spike-binding IgG antibody levels following COVID-19 vaccination among NHL and MM CAR T therapy recipients. Methods:This retrospective study was conducted at three Mayo Clinic sites on NHL and MM patients that received CAR T infusions from Sept 2016 to June 2021. Baseline characteristics were ascertained from medical records. All NHL and MM patients who had received CAR T at any point and were alive at the time that the COVID-19 vaccine first became available were eligible for inclusion for antibody response evaluation. For antibody response to vaccination, antibody spike values > 0.80 U/mL were considered positive. Results: Out of 104 CAR T infusions, 73 patients are alive at the time of this submission. We have had 7 patients with known COVID-19 pre-CAR T and all 7 are currently alive (5 have antibody titers and 2 have not been tested yet). Nineteen patients developed known COVID infection post-CAR T (13 alive and 6 deceased). The mortality of COVID post-CAR T in our sample was 31.5%. Furthermore, of the 13 patients that survived COVID-19, they received CAR T an average of 416 days prior to COVID-19 infection (median = 337, range = 54 - 1406); the 6 patients who died from COVID-19 had received CAR T an average of 250 days prior to COVID-19 infection (median = 164, range = 7 - 846). All 6 deceased patients did not receive COVID-19 vaccination pre-CAR T. Out of 17 CAR T patients tested for antibody spike titers post COVID-19 vaccination, 76.4% were able to mount an antibody response. More patients with MM had a higher titer response to the vaccine (>250 U/mL) compared to the NHL counterparts (0.80-249 U/mL). All patients that received the vaccine, regardless of antibody response, were alive at the time of this submission. Conclusions:The majority of CAR T recipients with NHL and MM are able to mount an antibody response following COVID-19 vaccination in our relatively small sample. The frequency of seroconversion among CAR T recipients seems to be similar to patients with hematologic malignancy who had received a hematopoietic cell transplant reported elsewhere. These findings are limited by our small sample size and may be influenced by the timing of vaccination relative to CAR T. Furthermore, almost half of our patients received IVIG post CAR T which could potentially cause false positive antibody results as pooled immunoglobulin preparations may contain COVID-19 antibodies from vaccinated healthy donors. To better understand the characteristics of the immunologic response against SARS-CoV-2 in patients post-CAR T, larger multicenter studies exploring both humoral and cellular immunity will be needed. JEWN, MI and JM are co-first authors and PV, HM and AR are co-senior authors. Figure 1 Figure 1. Disclosures Munoz: Physicians' Education Resource: Honoraria; Seattle Genetics: Honoraria; Bayer: Research Funding; Gilead/Kite Pharma: Research Funding; Celgene: Research Funding; Merck: Research Funding; Portola: Research Funding; Incyte: Research Funding; Genentech: Research Funding; Pharmacyclics: Research Funding; Seattle Genetics: Research Funding; Janssen: Research Funding; Millennium: Research Funding; Gilead/Kite Pharma, Kyowa, Bayer, Pharmacyclics/Janssen, Seattle Genetics, Acrotech/Aurobindo, Beigene, Verastem, AstraZeneca, Celgene/BMS, Genentech/Roche.: Speakers Bureau; Pharmacyclics/Abbvie, Bayer, Gilead/Kite Pharma, Pfizer, Janssen, Juno/Celgene, BMS, Kyowa, Alexion, Beigene, Fosunkite, Innovent, Seattle Genetics, Debiopharm, Karyopharm, Genmab, ADC Therapeutics, Epizyme, Beigene, Servier: Consultancy; Targeted Oncology: Honoraria; OncView: Honoraria; Kyowa: Honoraria. Bergsagel: Oncopeptides: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Patents & Royalties: human CRBN mouse; Pfizer: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Genetech: Consultancy, Honoraria; GSK: Consultancy, Honoraria. Wang: Incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding; LOXO Oncology: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Research Funding; InnoCare: Research Funding; Novartis: Research Funding; MorphoSys: Research Funding; Eli Lilly: Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees. Fonseca: Juno: Consultancy; Kite: Consultancy; Aduro: Consultancy; OncoTracker: Consultancy, Membership on an entity's Board of Directors or advisory committees; GSK: Consultancy; AbbVie: Consultancy; Patent: Prognosticaton of myeloma via FISH: Patents & Royalties; Caris Life Sciences: Membership on an entity's Board of Directors or advisory committees; Scientific Advisory Board: Adaptive Biotechnologies: Membership on an entity's Board of Directors or advisory committees; BMS: Consultancy; Amgen: Consultancy; Sanofi: Consultancy; Merck: Consultancy; Mayo Clinic in Arizona: Current Employment; Celgene: Consultancy; Takeda: Consultancy; Bayer: Consultancy; Janssen: Consultancy; Novartis: Consultancy; Pharmacyclics: Consultancy. Palmer: Sierra Oncology: Consultancy, Research Funding; CTI BioPharma: Consultancy, Research Funding; Protagonist: Consultancy, Research Funding; Incyte: Research Funding; PharmaEssentia: Research Funding. Dingli: Novartis: Research Funding; GSK: Consultancy; Apellis: Consultancy; Alexion: Consultancy; Sanofi: Consultancy; Janssen: Consultancy. Kapoor: Sanofi: Research Funding; AbbVie: Research Funding; Takeda: Research Funding; Karyopharm: Consultancy; Cellectar: Consultancy; BeiGene: Consultancy; Pharmacyclics: Consultancy; Sanofi: Consultancy; Amgen: Research Funding; Ichnos Sciences: Research Funding; Regeneron Pharmaceuticals: Research Funding; Glaxo SmithKline: Research Funding; Karyopharm: Research Funding. Kumar: Roche-Genentech: Consultancy, Research Funding; Oncopeptides: Consultancy; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Consultancy, Research Funding; Beigene: Consultancy; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; Adaptive: Membership on an entity's Board of Directors or advisory committees, Research Funding; Astra-Zeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Tenebio: Research Funding; Merck: Research Funding; Carsgen: Research Funding; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Research Funding; Bluebird Bio: Consultancy; Antengene: Consultancy, Honoraria; Sanofi: Research Funding. Paludo: Karyopharm: Research Funding. Bennani: Kymera: Other: Advisory Board; Vividion: Other: Advisory Board; Kyowa Kirin: Other: Advisory Board; Daichii Sankyo Inc: Other: Advisory Board; Purdue Pharma: Other: Advisory Board; Verastem: Other: Advisory Board. Ansell: Bristol Myers Squibb, ADC Therapeutics, Seattle Genetics, Regeneron, Affimed, AI Therapeutics, Pfizer, Trillium and Takeda: Research Funding. Lin: Kite, a Gilead Company: Consultancy, Research Funding; Merck: Research Funding; Gamida Cell: Consultancy; Takeda: Research Funding; Juno: Consultancy; Bluebird Bio: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy; Janssen: Consultancy, Research Funding; Sorrento: Consultancy; Legend: Consultancy; Vineti: Consultancy. Murthy: CRISPR Therapeutics: Research Funding.

Abstract Introduction: Acquired thrombotic thrombocytopenic purpura (aTTP) due to an acquired deficiency in the enzyme ADAMTS13 leads to ultra-large von Willebrand multimers, thrombocytopenia and microangiopathic hemolytic anemia. Complications include microvascular and macrovascular thrombosis. We present an unusual case of a patient with a history of refractory aTTP who experienced relapsed aTTP following COVID-19 vaccine. Case Description: A 57-year-old African-American male with a history of refractory aTTP experienced a relapse following 3 years of remission after receiving COVID-19 vaccination. The patient was initially diagnosed with aTTP in 2016, after presenting with symptoms of dark urine, mild headaches and transient episodes of aphasia and paresthesia. Due to symptoms and persistently low ADAMTS13 levels, he required prolonged and extensive treatment including over 5 weeks of daily therapeutic plasma exchange (TPE), followed by gradual reduction in frequency of TPE sessions, as well as trials of rituximab, eculizumab, steroids, mycophenolate mofetil and bortezomib. Ultimately, he achieved remission after 9 months of intermittent TPE, 3 months of weekly bortezomib 1 mg/m 2, mycophenolate mofetil up-titrated to 1,750 mg twice daily, and then slowly tapered off over a 2-year period. The patient was doing well for 3 years without manifestations of aTTP (2 years off all therapeutics), until he developed a petechial rash 7 weeks after receiving the second dose of the Moderna COVID-19 vaccine. He was found to have acute thrombocytopenia with platelets of 38 x 10 9/L (normal range 135-317 x 109/L), from a baseline of 200-300 x 10 9/L. He was referred to the emergency department, where additional labs were notable for mildly elevated LDH of 508 U/L (normal range 122-222 U/L), hemoglobin of 12.4 g/dL (normal range 13.2-16.6 g/dL), creatinine at baseline, and peripheral blood smear showing 1-3 schistocytes per high-powered field. ADAMTS13 activity level was t <5% (normal >/= 70%), with positive ADAMTS13 inhibitor screen and titer of 1.5 (normal <0.4), consistent with relapsed aTTP. The patient was admitted to the hospital, and initiated on daily TPE, with steroids and diphenhydramine prior to each TPE session. He quickly improved with TPE alone , but given his history of refractory aTTP, he was discharged on weekly rituximab for 4 weeks and caplacizumab 11 mg daily for 30 days. His platelets remained stable within the upper limit of normal during his 30 day course of caplacizumab. However, 3 weeks after completion of caplacizumab, he had an acute drop in his platelets to 23 x 10 9/L. His ADAMTS13 level was again found to be <5%, and inhibitor level was the highest that it had ever been at 11.4. He was again hospitalized and underwent 8 sessions of daily TPE, as well as re-initiation of caplacizumab, mycophenolate mofetil 500 mg bid (with increasing taper), and a prednisone taper. Intravenous Cyclophosphamide 750 mg/m 2 was also added every 3 weeks. With this regimen, patient's platelet count normalized and remain stable, and his ADAMTS13 activity level has reached 52-59%. Discussion: Cases of vaccine-induced immune thrombotic thrombocytopenia (VITT) have been described as a complication following vaccination with formulations containing replication-defective adenoviral vectors (AstraZeneca-Oxford and Johnson&Johnson COVID-19 vaccines)(Arepally and Ortel 2021, Simpson, Shi et al. 2021). VITT and aTTP are both immune-mediated, however, VITT is distinct and pathogenically linked to autoimmune heparin-induced thrombocytopenia (HIT), given the presence of anti-platelet factor 4 antibodies in these patients, whereas aTTP is due to reduction in ADAMTS13 level, secondary to an antibody inhibitor of ADAMTS13 (Arepally and Ortel 2021). Recently, cases have been reported of de novo aTTP developing shortly after COVID-19 vaccination with all available vaccines, except the Moderna (mRNA-1273) vaccine (Al-Ahmad, Al-Rasheed et al. 2021, de Bruijn, Maes et al. 2021, Maayan, Kirgner et al. 2021, Ruhe, Schnetzke et al. 2021, Waqar, Khan et al. 2021, Yocum and Simon 2021). Additionally, cases of relapsed aTTP have been described following only the BNT162B2 (Pfizer-BioNTech) vaccine (Maayan, Kirgner et al. 2021, Sissa, Al-Khaffaf et al. 2021). This is the first case, to our knowledge, reported in the literature of aTTP following vaccination with Moderna's mRNA-1273 vaccine. Disclosures No relevant conflicts of interest to declare.

Abstract Objectives: We identified a case of follicular lymphoma (FL) that transformed into a morphologic diffuse large B-cell lymphoma (DLBCL), which by gene expression profiling showed a primary mediastinal (PMBL)-like gene expression profile (GEP) (Lymph3Cx; Blood 2018;132:2401-5). A search identified 4 additional transformed FL (tFL) cases with a PMBL-like GEP, which we further studied to determine how similar these tFLs were to classic cases of PMBL. Methods: The morphology and previously reported immunophenotype were reviewed, and CD30, CD23, MAL, CD273/PDL2, and CD200 immunohistochemical stains (IHC) were performed. Whole exome sequencing (WES) and copy number analysis (CNA) to evaluate genes typically altered in FL and PMBL were performed. Results: None of the tFLs arose in the mediastinum or had a previous history of mediastinal disease. All cases showed typical centroblastic DLBCL cytology, with fine sclerosis typical of PMBL. 3/3 were GCB by the Hans IHC algorithm, 1/3 were MYC+, 3/3 BCL2+, 1/5 CD30+, 3/5 CD23+, 4/5 MAL+, 0/5 CD273/PDL2+, 1/5 CD200+, and 0/2 EBER+. Rearrangements of MYC, BCL2, or BCL6 were identified by FISH in 0/3, 1/3, and 2/3 cases, respectively. WES demonstrated sequence variants in genes associated with both FL (CREBBP [60%], KMT2D [40%], and TNFRSF14 [40%]) and PMBL (JAK-STAT pathway genes [80%], B2M [20%], and CD58 [20%]). 2 of the mutations identified in the tFLs have previously been shown to result in JAK-STAT activation (STAT6 p.E372K [PNAS 2016;113:13015-20] and SOCS1 p.F101L [Oncogene 2002;21:4351-62] identified in 1/5 cases each). CNA showed gains/amplification of REL in 3/5 cases, gains/amplification of STAT6 in 2/5, gains of large sections of chromosome 16, including IL4R, in 2/5, and both deletions and gains of 11q in 1/5. See Figure demonstrating the 5 cases on the Y-axis and the chromosomes on the X-axis. Conclusions: The tFLs in this small series seem to represent PMBL-like DLBCLs, rather than classic PMBLs, and have a blended pattern of immunophenotypic and genomic features between FL/DLBCL and PMBL. Although the cases express some PMBL-associated markers (CD23 and MAL), there is less frequent staining for others (CD30, CD273/PDL2, and CD200). The cases harbor both FL-associated and PMBL-associated sequence variants, including 40% with mutations known to activate the JAK-STAT pathway. This frequency of mutations in JAK-STAT pathway genes is higher than that seen in typical FL/DLBCL, but perhaps lower than in classic PMBL (Blood 2019;134:802-13). PMBL also frequently has gains/amplifications of 9p24.1, which was not seen in our cohort. However, gains/amplification of REL/2p, which is seen in approximately 50% of PMBL, was identified in 60% of the tFLs. The 11q aberration identified in 1 case would be unusual for PMBL, and is instead more commonly associated with a subset of aggressive lymphomas with Burkitt-like features (Haematologica 2019;104:1822-9). Recently, lymphomas with similar blended features between DLBCL and PMBL, which were not arising in the setting of tFL, have been reported (Duns G, et al. Blood 2021). Our study extends the types of biological transformations, in addition to more classic DLBCL, that can be seen in FL. These tFLs with blended PMBL-DLBCL biology may have implications for therapeutic decision making including targeted therapies used in PMBL. Figure 1 Figure 1. Disclosures Rimsza: NanoString Technologies: Other: Fee-for-service contract. Steidl: Curis Inc.: Consultancy; Trillium Therapeutics: Research Funding; Bayer: Consultancy; Epizyme: Research Funding; Seattle Genetics: Consultancy; AbbVie: Consultancy; Bristol-Myers Squibb: Research Funding.

Abstract Background Patients (pts) with aggressive B-cell non-Hodgkin lymphoma (NHL) progressing after anti-CD19 chimeric antigen receptor T (CART) cell therapy have poor prognosis and may benefit from new therapy options through clinical trials. However, in a single center report, only 12% of such pts were treated in trials (Chow et al. Am J Hematol, 2019). Identifying the reasons for this low enrollment is needed to design future studies for this population. Here, we evaluated the eligibility criteria for recent landmark trials for relapsed/refractory aggressive B-cell NHL to learn what eligibility barriers are present. Methods Pts with aggressive B-cell NHL who received FDA-approved CART cell therapy at Mayo Clinic (Rochester, Arizona, Florida) since 2018 and progressed after CART cell therapy were identified. The potential eligibility for the following key trials was evaluated: a) polatuzumab + bendamustine + rituximab, b) tafasitamab + lenalidomide, c) selinexor and d) loncastuximab. The eligibility for each trial was retrospectively assessed at the time of disease progression after CART cell therapy based on hemoglobin (Hb), absolute neutrophils count (ANC), platelet count (Plt), renal and liver function tests, ECOG performance status (PS), and central nervous system (CNS) involvement. Results Seventy-five pts had disease progression to axicabtagene ciloleucel (N=73, 97%) or tisagenlecleucel (N=2, 3%) and are included in this analysis. Median time to progression after CART was 2.1 months (IQR: 1.0 - 3.1). Thirteen (17%) pts were treated in clinical trials after progression following CART cell therapy, while 46 (61%) were treated off trials, and 16 (22%) pts never received any treatment after progression. At a median follow-up of 13.6 months (IQR: 9.1 - 26.7) from CART progression, the median overall survival (mOS) from CART progression was 5.8 months (95% CI 3.5 - 10.1) and 53 (71%) pts died. Thirty-eight pts (51%) did not meet eligibility criteria for any of the 4 recent landmark trials. Hematologic impairment was the most common barrier to inclusion of these patients in clinical trials: Hb < 9 g/dL n=23 (31%) or Hb < 10 g/dL n=36 (48%), ANC < 1.0 x 10 9/L n=19 (25%) or ANC < 1.5 x 10 9/L n=32 (43%), and Plt < 75 x 10 9/L n=30 (40%) or Plt < 90 x 10 9/L n=34 (45%). Renal (n=11, 15%) or liver dysfunction (n=5, 7%), CNS involvement (n=8, 11%) and ECOG PS > 2 (n=3, 4%) were less common reasons leading to exclusion from trials. Post CART trial ineligible pts had significantly shorter time to progression (median 1.7 months, IQR: 1.0 - 2.6 vs. 3.0 months IQR: 1.9 - 3.4, p < 0.01) and inferior overall response to CART (45% vs 67%, p = 0.06) compared to pts who met trial eligibility post CART. Baseline Hb (median Hb 9.5 g/dL, IQR: 8.5 - 10.5 vs. 10.9 g/dL, IQR: 9.7 - 12.2, p < 0.01) and Plt (median Plt 106 x 10 9/L IQR: 54 - 165 vs. 201 x 10 9/L IQR: 141 - 243, p < 0.01) were also significantly lower in pts ineligible for trials post CART. There were no significant differences between pts eligible or ineligible for trials with regards to age (median 59 vs. 60 years), number of prior therapies (median 3 vs. 3), prior autologous stem cell transplant (41% vs. 37%), bridging therapy (65% vs. 63%), baseline ANC (median 4,1 vs. 3,0 x10 9/L), or high-grade (grade ≥ 2) cytokine release syndrome (19% vs. 21%) or neurotoxicity (32%, vs. 42%), respectively. Survival after CART progression was significantly shorter (mOS 2.5 months, 95% CI: 1.6 - 5.1) for the 38 pts ineligible for trials compared to pts eligible for trials (mOS 10.6 months, 95% CI: 8.9 - NA), (p < 0.01). In the 59 pts who received therapy post CART progression, the mOS of pts treated on (n = 13) or off (n = 46) trials was 13.8 months (95% CI: 9.2 - NA) vs. 6.6 months (4.9 - 10.7), respectively (p = 0.047). Conclusion Approximately half of the pts (51%) with aggressive B-cell NHL progressing after CART cell therapy would have be excluded from landmark clinical trials. The current hematologic exclusion criteria are a major barrier to enrollment in clinical trials, which would exclude many pts who have disease progression within 3 months of CART cell therapy (ie, primary refractory disease), in whom cytopenia as a toxicity from therapy is prevalent. Given the known delayed hematologic recovery after CART cell therapy and the unmet need of pts progressing to CART cell therapy, the hematologic exclusion criteria should be adjusted to increase trial participation of this population, especially of those with primary refractory disease. Figure 1 Figure 1. Disclosures Munoz: Gilead/Kite Pharma, Kyowa, Bayer, Pharmacyclics/Janssen, Seattle Genetics, Acrotech/Aurobindo, Beigene, Verastem, AstraZeneca, Celgene/BMS, Genentech/Roche.: Speakers Bureau; Janssen: Research Funding; Pharmacyclics/Abbvie, Bayer, Gilead/Kite Pharma, Pfizer, Janssen, Juno/Celgene, BMS, Kyowa, Alexion, Beigene, Fosunkite, Innovent, Seattle Genetics, Debiopharm, Karyopharm, Genmab, ADC Therapeutics, Epizyme, Beigene, Servier: Consultancy; Seattle Genetics: Research Funding; Millennium: Research Funding; Pharmacyclics: Research Funding; Genentech: Research Funding; Incyte: Research Funding; Portola: Research Funding; Merck: Research Funding; Celgene: Research Funding; Gilead/Kite Pharma: Research Funding; Bayer: Research Funding; Seattle Genetics: Honoraria; Physicians' Education Resource: Honoraria; Targeted Oncology: Honoraria; OncView: Honoraria; Kyowa: Honoraria. Murthy: CRISPR Therapeutics: Research Funding. Maurer: Morphosys: Membership on an entity's Board of Directors or advisory committees, Research Funding; Nanostring: Research Funding; Kite Pharma: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; Genentech: Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees. Bennani: Purdue Pharma: Other: Advisory Board; Daichii Sankyo Inc: Other: Advisory Board; Kyowa Kirin: Other: Advisory Board; Vividion: Other: Advisory Board; Kymera: Other: Advisory Board; Verastem: Other: Advisory Board. Paludo: Karyopharm: Research Funding. Wang: Genentech: Research Funding; Incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding; MorphoSys: Research Funding; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees; Eli Lilly: Membership on an entity's Board of Directors or advisory committees; LOXO Oncology: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; InnoCare: Research Funding. Ansell: Bristol Myers Squibb, ADC Therapeutics, Seattle Genetics, Regeneron, Affimed, AI Therapeutics, Pfizer, Trillium and Takeda: Research Funding. Witzig: Karyopharm Therapeutics, Celgene/BMS, Incyte, Epizyme: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene/BMS, Acerta Pharma, Kura Oncology, Acrotech Biopharma, Karyopharm Therapeutics: Research Funding. Nowakowski: Celgene, NanoString Technologies, MorphoSys: Research Funding; Celgene, MorphoSys, Genentech, Selvita, Debiopharm Group, Kite/Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees. Lin: Vineti: Consultancy; Takeda: Research Funding; Sorrento: Consultancy; Novartis: Consultancy; Juno: Consultancy; Legend: Consultancy; Janssen: Consultancy, Research Funding; Bluebird Bio: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Merck: Research Funding; Gamida Cell: Consultancy; Kite, a Gilead Company: Consultancy, Research Funding.

Objective/background: Despite the success of chimeric antigen receptor (CAR) T-cell therapy in patients with aggressive non-Hodgkin lymphoma (aNHL), some patients still fail treatment, and their prognosis is dismal. Methods: We performed a retrospective study of aNHL patients treated with axicabtagene ciloleucel (axi-cel) at two Mayo Clinic centers between 2018 and 2020. We evaluated predictive factors, toxicities, and responses to salvage regimens after CAR T-cell therapy. Results: Thirty-four patients received axi-cel with a median length of hospitalization of 14 days. Cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome of any grade occurred in 91% and 41% of patients, respectively. Furthermore, 71% of patients responded to therapy, with 53% achieving a complete response (CR). The CRS grade and absolute lymphocyte count at leukapheresis (ALC Leuk ) correlated with CR and overall survival (OS), respectively. After a median follow-up of 6.8 months (interquartile range [IQR] 4.6–14.9), 15 patients (44%) showed progressive disease (PD). Most patients (60%) progressed during the first 3 months and had persistent CD19 tumor expression. Elevated C-reactive protein at baseline increased the risk of PD, whereas elevated ferritin increased PD and mortality risk. Twelve patients received salvage therapy, but only three responded. Median OS of relapsed/refractory patients to axi-cel was 3 months (IQR 1.3–5.1). Conclusion: The grade of CRS and ALC Leuk correlated with better outcomes to axi-cel therapy. In addition, elevated inflammatory markers at baseline were associated with PD and shorter survival. Relapses after treatment frequently occur within months after axi-cel infusion; they confer a poor prognosis and create an urgent need for novel and effective treatment options in this patient population.