Abstract CT215: LB1901: A phase 1, open-label, multicenter, multicohort study of CD4-targeted chimeric antigen receptor T cells (CD4-CAR-T) in relapsed or refractory T-cell lymphoma (TCL)

Background: Disease relapse is common with peripheral T-cell lymphomas (PTCL) or cutaneous T-cell lymphomas (CTCL). Adoptive immunotherapy with CD19 directed CAR-T cells is a standard option for B cell lymphoid malignancies in the relapsed setting. This study assesses the safety and preliminary efficacy of CD4 targeting autologous CAR-T, LB1901, in patients (pts) with CD4+ relapsed or refractory (R/R) TCL. A pre-clinical study showed LB1901 exhibited potent anti-tumor activity without off-target effects (Zeng 2021).

Methods: This is a phase 1, open-label, multicenter, multicohort study of LB1901 (NCT04712864; currently enrolling). Eligible pts are ≥18 years with histologically confirmed CD4+ PTCL-NOS (not otherwise specified); or CD4+ AITL (angioimmunoblastic T-cell lymphoma); or CD4+ CTCL (either MF [mycosis fungoides] or SS [Sézary syndrome]). In Part A (dose escalation), pts with SS must have ≤2,000 circulating Sézary cells/µL to ensure safety of pts with higher disease burden. In Part B, pts with >2,000 Sézary cells/µL is allowed. CD4 expressed on tumor cells must be confirmed within 3 months prior to apheresis. Other inclusion criteria include: R/R disease with ≥2 prior lines of systemic antineoplastic therapy; for pts with PTCL-NOS or AITL, ≥1 measurable lesion according to IWG Response Criteria (Cheson 2014) and for pts with CTCL, ≥stage IIB on TNMB-ISLC/EORTC staging system; identified HSCT donor available prior to enrollment (in the event of severe recurrent infections and prolonged lymphopenia for which pt may need an allogeneic HSCT as a safety rescue); and ECOG status of 0 or 1. Response will be evaluated based on IWG response criteria for PTCL and Global Composite Response for CTCL (Olsen 2007). The study will be conducted in 2 parts (Part A: dose escalation and Part B: dose expansion). Three dose levels (0.3 X 106, 1.0 X 106, and 3.0 X 106 CAR+ viable T cells/kg) will be evaluated (N=3-6 for each dose level) with an optional dose level minus 1 (0.1 X 106 CAR+ viable T cells/kg). Part B will include 2 cohorts, PTCL and CTCL (N=12-20 for each), after the recommended dose for expansion (RDE) has been identified in Part A. Enrolled pts will undergo apheresis for PBMC collection. LB1901 will be manufactured from autologous CD8+ T cells. Pts may receive optional bridging therapy and receive lymphodepleting chemotherapy with fludarabine 30mg/m2/day and cyclophosphamide 300mg/m2/day (Flu-Cy), for 3 days followed by LB1901. Primary endpoints are incidence, duration, and severity of AEs and laboratory abnormalities (Parts A and B) and DLT at each dose level (Part A). Secondary endpoints include overall response rate; duration of response; CAR-positive T cell counts and CAR transgene level in blood; and presence of anti-CAR antibody response. Exploratory endpoints include preliminary efficacy, pharmacokinetics, and CD4+ T cell counts.

Citation Format: Swaminathan P. lyer, David G. Maloney, Nora Bennani, Auris Huen, Muhammad Akram, Soo Kim, Chuan Wang, Zhiyin Liang, Henry Castro, Lida Pacaud, Mehdi Hamadani. LB1901: A phase 1, open-label, multicenter, multicohort study of CD4-targeted chimeric antigen receptor T cells (CD4-CAR-T) in relapsed or refractory T-cell lymphoma (TCL) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT215.

BASECAMP-1: Leveraging human leukocyte antigen (HLA) loss of heterozygosity (LOH) in solid tumors by next-generation sequencing (NGS) to identify patients with relapsed solid tumor for future logic-gated Tmod CAR T-cell therapy

TPS2676

Background: Solid tumors comprise > 90% of cancers. Metastatic colorectal cancer, non-small cell lung cancer, and pancreatic cancer are among the leading causes of cancer-related mortality (5-year overall survival: 14%, 6%, and 3%, respectively) (ACS. 2021). Chimeric antigen receptor (CAR) T-cell therapy has demonstrated clinical efficacy in hematologic malignancies (Neelapu S. et al. N Engl J Med. 2017). Translating engineered T-cell therapies to solid tumors has proven to be challenging due to a lack of tumor-specific targets that can discriminate cancer cells from normal cells. Previous studies using carcinoembryonic antigen (CEA) T-cell receptors and mesothelin (MSLN) CARs resulted in dose-limiting on-target, off-tumor toxicities (Parkhurst M, et al. Mol Ther. 2011; Tanyi J. Cellicon Valley '21). To create a therapeutic safety window, Tmod CAR T-cell therapy utilizes dual-signaling receptors to create a robust NOT logic gate capable of killing tumor cells, while leaving healthy cells intact (Hamburger A, et al. Mol Immunol. 2020). The 2 receptors in Tmod CAR T-cell therapy comprise an activator that recognizes an antigen on the surface of tumor cells that may also be present on normal cells, such as CEA and MSLN, and a blocker that recognizes a second surface antigen from an allele lost only in tumor cells. The frequency of HLA LOH among advanced GI solid tumor cancers in the Tempus real-world dataset is 16.3% with a range of 15.6%-20.8% between colorectal, pancreatic, and gastroesophageal tumors (Hecht R. et al. ASCO-GI 2022. Abstract #190). As such, HLA LOH offers a definitive tumor versus normal discriminator target for CAR T-cell therapy. Different activator/blocker combinations can be engineered with the Tmod platform technology and may be applied to T cells and natural killer cells in autologous and allogeneic settings. BASECAMP-1 is a currently enrolling observational study with key objectives of 1) To identify patients with somatic HLA LOH eligible for Tmod CAR T-cell therapy, and 2) To obtain leukapheresis and feasibility for the future EVEREST Tmod CAR T-cell trial. Methods: BASECAMP-1 (NCT04981119) patient eligibility has 2 parts: 1) Patients will be initially screened to identify germline HLA-A*02 heterozygosity by central NGS. If HLA-A*02 heterozygosity is confirmed, primary archival tumor tissue will be analyzed for somatic mutations by xT-Onco NGS testing. 2) If the tumor demonstrates HLA-A*02 LOH and the patient is eligible after screening, the patient will undergo leukapheresis. Banked T cells will be available for the autologous EVEREST Tmod CAR T-cell therapy interventional study to reduce waiting time at relapse. Clinical trial information: NCT04981119.

Health State Utilities for Adverse Events Associated with Chimeric Antigen Receptor T-Cell Therapy in Large B-Cell Lymphoma

BACKGROUND

Chimeric antigen receptor (CAR) T-cell therapy provides effective treatment for large B-cell lymphoma (LBCL). Cost-utility analyses examining and comparing the value of these treatments require health state utilities representing key characteristics to differentiate among therapies. This study estimated utilities for adverse events (AEs) associated with CAR T-cell therapy, including cytokine release syndrome (CRS) and neurological events (NEs).

METHODS

Health state vignettes were drafted based on literature review, AE reports from a trial of CAR T-cell therapy, and clinician input. Health states were valued in time trade-off interviews with general population participants in the UK. The first vignette described relapsed/refractory LBCL treated with CAR T-cell therapy without AEs. Five other vignettes had the same LBCL and treatment description, with the addition of an AE. Disutilities (i.e., utility decrease) associated with these AEs were calculated by subtracting the utility of the health state without AEs from those of the other health states.

RESULTS

Interviews were completed with 218 participants (50% male; mean age 49 years). Mean (standard deviation [SD]) utility for CAR T-cell therapy without AEs was 0.73 (0.30). Mean (SD) disutilities associated with CRS were -0.01 (0.04) for grade 1, -0.05 (0.09) for grade 2, and -0.23 (0.24) for grade 3/4. Mean (SD) disutilities associated with NEs were -0.04 (0.07) for grade 1/2 and -0.18 (0.22) for grade 3/4.

CONCLUSIONS

More severe AEs were associated with greater disutilities. Health state utilities estimated in this study may be useful in cost-effectiveness models examining the value of CAR T-cell therapy in patients with LBCL.

Severe cytokine release syndrome is associated with hematologic toxicity following CD19 CAR T-cell therapy

CD19-targeted chimeric antigen receptor (CAR) T-cell therapy has demonstrated remarkable efficacy in patients with relapsed/refractory B-cell malignancies; however, it is associated with toxicities including cytokine release syndrome (CRS), neurotoxicity, and impaired hematopoietic recovery. The latter is associated with high-grade cytopenias requiring extended growth factor or transfusional support, potentially leading to additional complications such as infection or hemorrhage. To date, the factors independently associated with hematologic toxicity have not been well characterized. To address this deficit, we retrospectively analyzed 173 patients who received defined-composition CD19 CAR T-cell therapy in a phase 1/2 clinical trial (https://clinicaltrials.gov; NCT01865617), with primary end points of absolute neutrophil count and platelet count at day-28 after CAR T-cell infusion. We observed cumulative incidences of neutrophil and platelet recovery of 81% and 75%, respectively, at 28 days after infusion. Hematologic toxicity was noted in a significant subset of patients, with persistent neutropenia in 9% and thrombocytopenia in 14% at last follow-up. Using debiased least absolute shrinkage selector and operator regression analysis for high-dimensional modeling and considering patient-, disease-, and treatment-related variables, we identified increased CRS severity as an independent predictor for decreased platelet count and lower prelymphodepletion platelet count as an independent predictor of both decreased neutrophil and platelet counts after CD19 CAR T-cell infusion. Furthermore, multivariable models including CRS-related cytokines identified associations between higher peak serum concentrations of interleukin-6 and lower day-28 cell counts; in contrast, higher serum concentrations of transforming growth factor-β1 were associated with higher counts. Our findings suggest that patient selection and improved CRS management may improve hematopoietic recovery after CD19 CAR T-cell therapy.

Matching-adjusted indirect treatment comparison of chimeric antigen receptor T-cell therapies for third-line or later treatment of relapsed or refractory large B-cell lymphoma: lisocabtagene maraleucel versus tisagenlecleucel

Background

There are no head-to-head clinical studies comparing chimeric antigen receptor (CAR) T-cell therapies for the treatment of relapsed or refractory aggressive large B-cell lymphomas. Naive, indirect comparisons may be inappropriate, as the study designs and patient populations could differ substantially. Matching-adjusted indirect comparisons (MAIC) can reduce many biases associated with indirect comparisons between studies. To determine the comparative efficacy and safety of lisocabtagene maraleucel (liso-cel) to tisagenlecleucel, we describe an unanchored MAIC of the pivotal studies TRANSCEND NHL 001 (TRANSCEND; NCT02631044; liso-cel) and JULIET (NCT02445248; tisagenlecleucel).

Methods

Individual patient data (IPD) from TRANSCEND were available to the authors; for the JULIET pivotal study, summary-level data from the published study were used. To balance the populations between two studies, IPD from TRANSCEND were adjusted to match the marginal distribution (e.g., mean, variance) of clinical factors among patients from JULIET.

Results

Results from the primary MAIC showed liso-cel had statistically significant greater efficacy than tisagenlecleucel (objective response rate: odds ratio [OR] = 2.78, 95% confidence interval [CI]: 1.63‒4.74; complete response rate: OR = 2.01, 95% CI: 1.22‒3.30; progression-free survival: hazard ratio [HR] = 0.65, 95% CI: 0.47‒0.91; overall survival: HR = 0.67, 95% CI: 0.47‒0.95). MAIC of safety outcomes showed lower ORs for all-grade and grade ≥ 3 cytokine release syndrome, and grade ≥ 3 prolonged cytopenia for liso-cel when compared with tisagenlecleucel; there were no statistically significant differences detected for other safety outcomes.

Conclusions

Overall, this MAIC of two CAR T-cell therapies indicates liso-cel had favorable efficacy and a comparable or better safety profile relative to tisagenlecleucel.

Clinical trial registration: ClinicalTrials.gov identifiers: NCT02631044 and NCT02445248.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40164-022-00268-z.

Next generation sequencing (NGS) to identify relapsed gastrointestinal (GI) solid tumor patients with human leukocyte antigen (HLA) loss of heterozygosity (LOH) for future logic-gated CAR T therapy to reduce on target off tumor toxicity

190

Background: Metastatic colorectal (CRC), pancreatic (PANC), and gastroesophageal (GE) cancers are the leading causes of GI cancer–related mortality (5-yr survival rate, 14%, 3% and ̃5-6%, respectively). T-cell immunotherapy targeting GI-associated tumor antigens has been attempted, but efficacy has been constrained by on-target off-tumor toxicity, limiting the therapeutic window. The Tmod (TM) platform is an AND-NOT logic-gated CAR T modular system, versions of which have a CEA- or MSLN-targeting CAR activator and a separate HLA-A*02-targeting blocker receptor to protect normal cells. Tmod CAR T exploits HLA LOH, common in GI malignancies (10-33% in primary solid tumors [TCGA]) and can kill tumor cells without harming healthy cells in vitro and in vivo. However, the prevalence of HLA LOH across GI tumors is unknown in the real-world setting. We utilized the Tempus xT oncology NGS database of patients with multiple GI tumors. From a standard-of-care NGS assay, GI cancer patients can be readily identified for HLA LOH and future treatment with Tmod CAR T therapy. Methods: The occurrence of HLA LOH in GI tumors of 1439 patients was assessed using paired germline and somatic DNA sequencing using a research assay [6]. CRC, PANC and GE patients with ≥ stage 3 were then extracted, and rates of HLA LOH were identified (ie, whether loss occurred across high-frequency HLA-A alleles). In addition, mutations in KRAS and BRAF, as well as MSI status were stratified to determine any association with HLA-A LOH. Results: HLA-A LOH was detected in 830 (17.3%) of all solid tumor records, and a similar proportion when all GI cancer records were analyzed (17.0%). For GI subtypes, these values ranged from 13.5% to 23.1% (Table). No high-frequency HLA-A allele (A*01, A*02, A*03, A*11) was more likely to be lost. Clinical biomarkers ( KRAS, BRAF and MSI status) were not associated with HLA-LOH. Conclusions: The frequency of HLA LOH among advanced solid tumor cancers in this dataset is 17.3%, with a range of 13.5-23% between CRC, PANC and GE. The HLA LOH frequency observed in these GI tumors is consistent with that in primary tumors from TCGA, which also used germline-matched and tumor samples. Clinical biomarkers were not associated with HLA LOH. Tempus NGS was able to identify HLA LOH, which can be used for Tmod CAR T therapy to an enhanced therapeutic window. Identification of these patients in BASECAMP-1 (NCT04981119) will enable novel Tmod CAR T therapy. [Table: see text]

Megadose 90Y-ibritumomab tiuxetan prior to allogeneic transplantation is effective for aggressive large B-cell lymphoma

Allogeneic hematopoietic cell transplantation (allo-HCT) can be curative for relapsed or refractory B-cell lymphomas (BCLs), although outcomes are worse in aggressive disease, and most patients will still experience relapse. Radioimmunotherapy using 90Y-ibritumomab tiuxetan can induce disease control across lymphoma subtypes in a dose-dependent fashion. We hypothesized that megadoses of 90Y-ibritumomab tiuxetan with reduced-intensity conditioning could safely produce deeper remissions in aggressive BCL further maintained with the immunologic effect of allo-HCT. In this phase 2 study, CD20+ BCL patients received outpatient 90Y-ibritumomab tiuxetan (1.5 mCi/kg; maximum, 120 mCi), fludarabine, and then 2 Gy total body irradiation before HLA-matched allo-HCT. Twenty patients were enrolled after a median of 4.5 prior lines of therapy, including 14 with prior autologous transplant and 4 with prior anti-CD19 chimeric T-cellular therapy. A median 90Y-ibritumomab tiuxetan activity of 113.6 mCi (range, 71.2-129.2 mCi) was administered, delivering a median of 552 cGy to the liver (range, 499-2411 cGy). The estimated 1- and 5-year progression-free survival was 55% (95% confidence interval [CI], 31-73) and 50% (95% CI, 27-69) with a median progression-free survival of 1.57 years. The estimated 1- and 5-year overall survival was 80% (95% CI, 54-92) and 63% (95% CI, 38-81) with a median overall survival of 6.45 years. Sixteen patients (80%) experienced grade 3 or higher toxicities, although nonrelapse mortality was 10% at 1 year. No patients developed secondary acute myeloid leukemia/myelodysplastic syndrome. Megadose 90Y-ibritumomab tiuxetan, fludarabine, and low-dose total body irradiation followed by an HLA-matched allo-HCT was feasible, safe, and effective in treating aggressive BCL, exceeding the prespecified end point while producing nonhematologic toxicities comparable to those of standard reduced-intensity conditioning regimens.

Humoral immunogenicity of the seasonal influenza vaccine before and after CAR-T-cell therapy: a prospective observational study

Recipients of chimeric antigen receptor-modified T (CAR-T) cell therapies for B cell malignancies have profound and prolonged immunodeficiencies and are at risk for serious infections, including respiratory virus infections. Vaccination may be important for infection prevention, but there are limited data on vaccine immunogenicity in this population. We conducted a prospective observational study of the humoral immunogenicity of commercially available 2019-2020 inactivated influenza vaccines in adults immediately prior to or while in durable remission after CD19-, CD20-, or B cell maturation antigen-targeted CAR-T-cell therapy, as well as controls. We tested for antibodies to all four vaccine strains using neutralization and hemagglutination inhibition (HAI) assays. Antibody responses were defined as at least fourfold titer increases from baseline. Seroprotection was defined as a HAI titer ≥40. Enrolled CAR-T-cell recipients were vaccinated 14-29 days prior to (n=5) or 13-57 months following therapy (n=13), and the majority had hypogammaglobulinemia and cellular immunodeficiencies prevaccination. Eight non-immunocompromised adults served as controls. Antibody responses to ≥1 vaccine strain occurred in 2 (40%) individuals before CAR-T-cell therapy and in 4 (31%) individuals vaccinated after CAR-T-cell therapy. An additional 1 (20%) and 6 (46%) individuals had at least twofold increases, respectively. One individual vaccinated prior to CAR-T-cell therapy maintained a response for >3 months following therapy. Across all tested vaccine strains, seroprotection was less frequent in CAR-T-cell recipients than in controls. There was evidence of immunogenicity even among individuals with low immunoglobulin, CD19⁺ B cell, and CD4⁺ T-cell counts. These data support consideration for vaccination before and after CAR-T-cell therapy for influenza and other relevant pathogens such as SARS-CoV-2, irrespective of hypogammaglobulinemia or B cell aplasia. However, relatively impaired humoral vaccine immunogenicity indicates the need for additional infection-prevention strategies. Larger studies are needed to refine our understanding of potential correlates of vaccine immunogenicity, and durability of immune responses, in CAR-T-cell therapy recipients.

Matching-adjusted indirect treatment comparison of liso-cel versus axi-cel in relapsed or refractory large B cell lymphoma

Background

In the absence of randomized studies directly comparing chimeric antigen receptor T cell therapies, this study used matching-adjusted indirect comparisons (MAIC) to evaluate the comparative efficacy and safety of lisocabtagene maraleucel (liso-cel) versus axicabtagene ciloleucel (axi-cel) in patients with relapsed or refractory large B cell lymphoma (LBCL).

Methods

Primary data sources included individual patient data from the TRANSCEND NHL 001 study (TRANSCEND [NCT02631044]; N = 256 for efficacy set, N = 269 for safety set) for liso-cel and summary-level data from the ZUMA-1 study (NCT02348216; N = 101 for efficacy set, N = 108 for safety set) for axi-cel. Inter-study differences in design, eligibility criteria, baseline characteristics, and outcomes were assessed and aligned to the extent feasible. Clinically relevant prognostic factors were adjusted in a stepwise fashion by ranked order. Since bridging therapy was allowed in TRANSCEND but not ZUMA-1, the initial efficacy and safety analyses included bridging therapy use as a matching factor (TRANSCEND patients who received bridging therapy were removed). Subsequent sensitivity analyses excluded this matching factor.

Results

The initial analysis showed similar MAIC-weighted efficacy outcomes between TRANSCEND and ZUMA-1 for overall and complete response rates (odds ratio [95% confidence interval (CI)], 1.40 [0.56–3.49] and 1.21 [0.56–2.64], respectively) and for overall survival and progression-free survival (hazard ratio [95% CI], 0.81 [0.44–1.49] and 0.95 [0.58–1.57], respectively). MAIC-weighted safety outcomes favored liso-cel, with significantly lower odds of all-grade and grade ≥ 3 cytokine release syndrome (odds ratio [95% CI], 0.03 [0.01–0.07] and 0.08 [0.01–0.67], respectively) and study-specific neurological events (0.16 [0.08–0.33] and 0.05 [0.02–0.15], respectively). Efficacy and safety outcomes remained similar in sensitivity analyses, which did not include use of bridging therapy as a matching factor.

Conclusions

After matching and adjusting for clinically relevant prognostic factors, liso-cel demonstrated comparable efficacy and a more favorable safety profile compared with axi-cel in patients with third- or later-line relapsed or refractory LBCL.

Trial registration: NCT02631044 and NCT02348216

Supplementary Information

The online version contains supplementary material available at 10.1186/s13045-021-01144-9.

Antibodies against vaccine-preventable infections after CAR-T cell therapy for B cell malignancies

BACKGROUND

Little is known about pathogen-specific humoral immunity after chimeric antigen receptor–modified T (CAR-T) cell therapy for B cell malignancies.

METHODS

We conducted a prospective cross-sectional study of CD19-targeted or B cell maturation antigen–targeted (BCMA-targeted) CAR-T cell therapy recipients at least 6 months posttreatment and in remission. We measured pathogen-specific IgG against 12 vaccine-preventable infections and the number of viral and bacterial epitopes to which IgG was detected (“epitope hits”) using a serological profiling assay. The primary outcome was the proportion of participants with IgG levels above a threshold correlated with seroprotection for vaccine-preventable infections.

RESULTS

We enrolled 65 children and adults a median of 20 months after CD19- (n = 54) or BCMA- (n = 11) CAR-T cell therapy. Among 30 adults without IgG replacement therapy (IGRT) in the prior 16 weeks, 27 (90%) had hypogammaglobulinemia. These individuals had seroprotection to a median of 67% (IQR, 59%–73%) of tested infections. Proportions of participants with seroprotection per pathogen were comparable to population-based studies, but most individuals lacked seroprotection to specific pathogens. Compared with CD19-CAR-T cell recipients, BCMA-CAR-T cell recipients were half as likely to have seroprotection (prevalence ratio, 0.47; 95% CI, 0.18–1.25) and had fewer pathogen-specific epitope hits (mean difference, –90 epitope hits; 95% CI, –157 to –22).

CONCLUSION

Seroprotection for vaccine-preventable infections in adult CD19-CAR-T cell recipients was comparable to the general population. BCMA-CAR-T cell recipients had fewer pathogen-specific antibodies. Deficits in both groups support the need for vaccine and immunoglobulin replacement therapy studies.

FUNDING

Swiss National Science Foundation (Early Postdoc Mobility grant P2BSP3_188162), NIH/National Cancer Institute (NIH/NCI) (U01CA247548 and P01CA018029), NIH/NCI Cancer Center Support Grants (P30CA0087-48 and P30CA015704-44), American Society for Transplantation and Cellular Therapy, and Juno Therapeutics/BMS.

In this prospective study, we investigated antibodies against vaccine-preventable infections and other pathogen-specific antibodies in individuals with remission after CAR-T cell therapy for B lineage malignancies.

Allogeneic hematopoietic cell transplantation with non-myeloablative conditioning for patients with hematologic malignancies: Improved outcomes over two decades

We have used a non-myeloablative conditioning regimen for allogeneic hematopoietic cell transplantation for the past twenty years. During that period, changes in clinical practice have been aimed at reducing morbidity and mortality from infections, organ toxicity, and graft-versus-host disease. We hypothesized that improvements in clinical practice led to better transplantation outcomes over time. From 1997-2017, 1,720 patients with hematologic malignancies received low-dose total body irradiation +/- fludarabine or clofarabine before transplantation from HLA-matched sibling or unrelated donors, followed by mycophenolate mofetil and a calcineurin inhibitor ± sirolimus. We compared outcomes in three cohorts by year of transplantation: 1997 +/- 2003 (n=562), 2004 +/- 2009 (n=594), and 2010 +/- 2017 (n=564). The proportion of patients ≥60 years old increased from 27% in 1997 +/- 2003 to 56% in 2010-2017, and with scores from the Hematopoietic Cell Transplantation Comborbidity Index of ≥3 increased from 25% in 1997 +/- 2003 to 45% in 2010 +/- 2017. Use of unrelated donors increased from 34% in 1997 +/- 2003 to 65% in 2010-2017. When outcomes from 2004 +/- 2009 and 2010-2017 were compared to 1997 +/- 2003, improvements were noted in overall survival (P=.0001 for 2004-2009 and P <.0001 for 2010-2017), profression-free survival (P=.002 for 2004-2009 and P <.0001 for 2010 +/- 2017), non-relapse mortality (P<.0001 for 2004 +/- 2009 and P <.0001 for 2010 +/- 2017), and in rates of grades 2 +/- 4 acute and chronic graft-vs.-host disease. For patients with hematologic malignancies who underwent transplantation with non-myeloablative conditioning, outcomes have improved during the past two decades. Trials reported are registered under ClinicalTrials.gov identifiers: NCT00003145, NCT00003196, NCT00003954, NCT00005799, NCT00005801, NCT00005803, NCT00006251, NCT00014235, NCT00027820, NCT00031655, NCT00036738, NCT00045435, NCT00052546, NCT00060424, NCT00075478, NCT00078858, NCT00089011, NCT00104858, NCT00105001, NCT00110058, NCT00397813, NCT00793572, NCT01231412, NCT01252667, NCT01527045.

Updated outcomes with axicabtagene ciloleucel (axi-cel) retreatment (reTx) in patients (pts) with relapsed/refractory (R/R) indolent non-Hodgkin lymphoma (iNHL) in ZUMA-5

7548

Background: ZUMA-5 is a Phase 2 study of axi-cel anti-CD19 CAR T-cell therapy in pts with R/R iNHL (follicular lymphoma [FL]; marginal zone lymphoma [MZL]). In the primary analysis, 11 pts (9 FL; 2 MZL) were retreated with axi-cel, achieving an overall response rate (ORR) of 100% (91% complete response [CR] rate) at a median follow-up of 2.3 mo post-reTx, with no Grade ≥3 cytokine release syndrome (CRS) or neurologic events (NEs; Chavez et al. ASH 2020. #2036). Here, we report updated clinical and translational outcomes with longer follow-up in pts retreated with axi-cel in ZUMA-5. Methods: Eligible pts with FL or MZL had R/R disease after ≥2 lines of therapy. Pts were considered for reTx if they progressed after a response at mo 3, had no evidence of CD19-negative relapse in biopsy, had no axi-cel neutralizing antibodies, and had no Grade 4 CRS or NEs with 1st Tx. Retreatment was per investigator discretion. At both Txs, pts received axi-cel (2×106 CAR T cells/kg) after conditioning chemotherapy. Results: As of 9/14/2020, 13 pts with iNHL (11 FL; 2 MZL) received axi-cel reTx, with 2 pts retreated after the primary analysis. Before their 1st Tx, pts had median 4 prior lines of therapy; 85% had stage 3–4 disease; 82% had FLIPI of ≥3; 46% were POD24; 77% had refractory disease. Among the 13 retreated pts, 85% had a CR to 1st Tx. Median 1st duration of response (DOR) was 8.2 mo. Detectable CD19 was confirmed in all evaluable biopsies from retreated pts at relapse, and median time from 1st Tx to reTx was 10.6 mo. Following reTx, the ORR was 100% (77% CR rate). After a median follow-up of 11.4 mo, the median DOR had not yet been reached; 46% of retreated pts had ongoing responses at data cutoff. At 1st Tx, CRS occurred in 9 pts (5 Grade 1, 4 Grade 2); NEs occurred in 5 (3 Grade 1, 1 Grade 2, 1 Grade 3). At reTx, CRS occurred in 8 pts (6 Grade 1, 2 Grade 2); NEs occurred in 4 (3 Grade 1, 1 Grade 2). Median peak levels of biomarkers typically associated with severe CRS and NEs were similar at reTx and 1st Tx (IL-6, 7.7 vs 5.7 pg/mL; IL-2, 1.8 vs 0.9 pg/mL; IFN-γ, 62.9 vs 64.2 pg/mL). In the 11 retreated pts with FL, tumor burden (median sum of product diameters [SPD]) was lower before reTx vs 1st Tx (1416 vs 4770 mm2). Engraftment index (CAR T-cell expansion relative to SPD) is an indirect proxy for effector:target ratio and a key covariate of response to axi-cel (Locke et al. Blood Adv. 2020). Though median peak CAR T-cell levels appeared lower at reTx vs 1st Tx (5.2 vs 14.3 CAR+ cells/µL blood), engraftment index was similar (0.003 vs 0.005 cells/µL×mm2). Conclusions: Axi-cel reTx achieved deep and durable responses, with an acceptable safety profile. Tumor CD19 positivity was maintained at relapse, and engraftment index was similar at both Txs, comparing favorably to previous reports in aggressive lymphomas (Locke et al. ASCO 2020. #8012). These data suggest axi-cel reTx is a promising option for pts with R/R iNHL. Clinical trial information: NCT03105336.

CD19 CAR T-cell product type independently impacts CRS and ICANS severity in patients with aggressive NHL

7532

Background: CD19-targeted chimeric antigen receptor-engineered (CD19 CAR) T cells achieve high response rates in patients (pts) with relapsed or refractory (R/R) aggressive B-cell non-Hodgkin lymphoma (NHL), but are limited by cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS). Pivotal trial data suggested distinct toxicity risks across CD19 CAR T-cell products, but differences in pt and disease characteristics may have confounded these observations. Thus, we assessed the independent impact of 3 CD19 CAR T-cell products (axicabtagene ciloleucel[axicel], tisagenlecleucel [tisacel], and JCAR014) on CRS and ICANS severity in 136 pts with R/R aggressive NHL. Methods: We retrospectively analyzed aggressive NHL pts treated at our institutions with cyclophosphamide and fludarabine lymphodepletion (LD) followed by CD19 CAR T-cell therapy. Axicel and tisacel pts were treated off trial using commercial products. JCAR014 (defined-composition 4-1BB-costimulated CD19 CAR T cells) was administered in all pts at the dose of 2x106/kg on a phase I/II clinical trial (NCT01865617). CRS and ICANS were graded according to the ASTCT criteria and CTCAE 4.03, respectively. We used multivariable proportional odds logistic regression to model CRS and ICANS grade. Results: The CAR T-cell product was axicel, tisacel, or JCAR014 in 50%, 28%, and 22% of pts, respectively. Compared to axicel pts, we observed higher preLD LDH levels in tisacel and JCAR014 pts, and lower preLD albumin with tisacel (p < 0.001) with comparable age and hematopoietic cell transplantation comorbidity (HCT-CI) indexes across CAR T-cell products. Higher day-28 overall response rate by Lugano criteria was observed after axicel (71%) compared to tisacel (56%) and JCAR014 (53%). Adjusting for age, HCT-CI, preLD LDH, preLD albumin, CAR T-cell product type was associated with CRS severity (tisacel versus [vs] axicel, OR = 0.45, p = 0.05; JCAR014 vs axicel, OR = 0.29, p = 0.005;). Age had limited or no impact on CRS severity (OR 95%CI, 0.97-1.02), while the effect of HCT-CI was undetermined (OR 95%CI, 0.85-1.27). In a multivariable model including the same covariates as above, CAR T-cell product type (tisacel vs axicel, OR =.14, p <.001; JCAR014 vs axicel, OR = 0.31, p = 0.009), preLD LDH (OR, 3.96 per log10 increase; p = 0.04) and age (OR per 10-year increase, 1.32; p =.06) were associated with ICANS severity. Interaction effect testing suggested effect modification of age by the CAR T-cell product type (tisacel/JCAR014 versus axicel, p = 0.06); using a multivariable model including this interaction term, the predicted probabilities of grade ≥3 ICANS in a 70 year-old after axicel, tisacel, and JCAR014 were 40%, 6%, and 8%, respectively. Conclusions: CAR T-cell product type independently impacts CRS and ICANS severity in NHL pts. Our findings provide key insights to guide patient and CAR T-cell product selection.

Phase I study of adoptive immunotherapy for advanced MUC1* positive breast cancer with autologous T cells engineered to express a chimeric antigen receptor, huMNC2-CAR44 specific for a cleaved form of MUC1 (MUC1*)

TPS2663

Background: Chimeric antigen receptor (CAR) T cell therapy targeting CD19 results in marked tumor regression for patients with CD19+ malignancies. It would be ideal to extend the success of CAR-T cell therapy to epithelial cancers. MUC1* is a post-translationally modified/cleaved form of mucin 1 (MUC1) that is frequently expressed on breast tumors, functions as a growth factor receptor, and a promising antigen for CAR-T cell therapy. Minerva Biotechnologies developed a CAR (huMNC2-CAR44) which recognizes MUC1* and does not bind to full-length or MUC1* negative cells. huMNC2-CAR44 product consists of autologous T cells transduced with a lentiviral vector encoding humanized MNC2-scFv (MUC1* targeting head), sequences from CD8 𝛼 leader, hinge and transmembrane domains, 4-1BB and CD3ζ domains. Methods: NCT04020575 is a phase I study evaluating the safety of adoptively transferred autologous T cells genetically modified to express huMNC2-CAR44 in patients with metastatic MUC1* positive breast cancer. After screening, leukapheresis is performed, CD8+ and CD4+ T cells are selected, transduced with huMNC2-CAR44, expanded, and antigen stimulated in vitro. Lymphodepletion with cyclophosphamide and fludarabine is followed by infusion of huMNC2-CAR44 CAR-T cells in escalating doses (3.3 x 105 CAR+ T cells/kg – 1 x 107 CAR+ T cells/kg). Key inclusion criteria include metastatic breast cancer of known ER, PR and HER2 status, MUC1* membrane expression > or = 30% with 2+ staining by IHC, measurable or evaluable disease, receipt of standard systemic therapies known to confer benefit, age > 18, informed consent, adequate organ function, and KPS > or = 60%. Patients with active autoimmune disease, uncontrolled infection, anticipated survival < 3 months, and/or untreated CNS metastases are not eligible. The primary objective is to identify the maximum tolerated (MTD) dose of huMNC2-CAR44 T cells by CTCAE v5 and Lee criteria. Secondary objectives include persistence and phenotype of adoptively transferred huMNC2-CAR44 T cells and preliminary antitumor activity. Exploratory objectives include trafficking of huMNC2-CAR44 T cells to tumor sites, effector function of huMNC2-CAR44 T cells in vivo, association between tumor MUC1* expression and huMNC2-CAR44 T cell persistence and response, change in tumor immune microenvironment by multiplex IHC in pre- and post-treatment tumor biopsies. Dose escalation is completed using a "3+3" design. Once the MTD has been determined, up to 15 more patients will be enrolled in each of 3 expansion cohorts (Luminal, HER2 positive, and TNBC) to inform future huMNC2-CAR44 T cell trials. Study is open to screening and enrollment in dose escalation. Up to 69 patients may be enrolled in dose escalation and expansion phases. Clinical trial information: NCT04020575.

Outcomes in ZUMA-5 with axicabtagene ciloleucel (axi-cel) in patients (pts) with relapsed/refractory (R/R) indolent non-Hodgkin lymphoma (iNHL) who had the high-risk feature of progression within 24 months from initiation of first anti-CD20–containing chemoimmunotherapy (POD24)

7515

Background: POD24 is an indicator of poor survival in iNHL (Casulo & Barr. Blood. 2019). In the ZUMA-5 Phase 2 study of axi-cel anti-CD19 CAR T-cell therapy in pts with R/R iNHL, overall response rates (ORR) after 17.5 months median follow-up were similarly high in those with and without POD24 (93% and 92%; Jacobson et al. ASH 2020. #700). Here, we report updated outcomes with longer follow-up in pts with POD24 in ZUMA-5. Methods: Adults with R/R follicular lymphoma (FL) or marginal zone lymphoma (MZL) after ≥2 lines of therapy underwent leukapheresis followed by conditioning therapy and axi-cel infusion (2×106 CAR T cells/kg). Axi-cel–treated pts with available data on progression after an anti-CD20 mAb + alkylating agent were included. The updated efficacy analysis occurred when ≥80 treated pts with FL had ≥18 months follow-up. Results: Of 129 pts at baseline, 81 pts (63%; 68 FL, 13 MZL) had POD24 and 48 pts (37%; 40 FL, 8 MZL) did not have POD24. Median prior lines of therapy in pts with and without POD24 were 3 and 3.5, respectively. High-risk characteristics of pts with and without POD24 included stage III/IV disease, 83% and 94%; ≥3 FLIPI, 44% and 43%; high tumor bulk (GELF), 51% and 44%; and refractory disease, 77% and 63%, respectively. With 23.3 months median follow-up, ORR among efficacy-evaluable pts with POD24 (n = 61) and without POD24 (n = 37) was 92% each (complete response rates, 75% and 86%). At data cutoff, 52% of pts with POD24 and 70% without POD24 had ongoing responses. Median duration of response, progression-free survival, and overall survival were not reached in pts with and without POD24; 18-month estimated rates were 60% and 78%, 55% and 84%, and 85% and 94%, respectively. Incidences of Grade ≥3 adverse events were similar in pts with and without POD24 (84% and 88%), including cytopenias (69% and 65%) and infections (15% and 21%). Grade ≥3 cytokine release syndrome (CRS) occurred in 9% and 2% of pts with and without POD24, respectively; Grade ≥3 neurologic events (NEs) occurred in 17% of pts each. Median times to onset were similar in pts with and without POD24 for CRS (4 days each) and NEs (8 days and 7 days); median durations of CRS (7 days and 5 days) and NEs (11 days and 13 days) were also similar between groups. In efficacy-evaluable pts with FL, median peak CAR T-cell levels were similar in pts with and without POD24 (35.8 cells/μL and 34.5 cells/μL). Peak levels of key inflammatory biomarkers and axi-cel product attributes were generally similar in pts with and without POD24. Conclusions: Axi-cel showed a high rate of durable responses in pts with POD24 iNHL, a population with high-risk disease. Efficacy results, as well as safety and pharmacological profiles, appeared largely comparable between groups, with the exception of PFS rates. Clinical trial information: NCT03105336.

Humoral immunogenicity of the seasonal influenza vaccine before and after CAR-T-cell therapy

Recipients of chimeric antigen receptor-modified T (CAR-T) cell therapies for B-cell malignancies are immunocompromised and at risk for serious infections. Vaccine immunogenicity is unknown in this population. We conducted a prospective observational study of the humoral immunogenicity of 2019-2020 inactivated influenza vaccines (IIV) in children and adults immediately prior to (n=7) or 13-57 months after (n=15) CD19-, CD20-, or BCMA-targeted CAR-T-cell therapy, as well as controls (n=8). Individuals post-CAR-T-cell therapy were in remission. We tested for antibodies to 4 vaccine strains at baseline and ≥1 time point after IIV using neutralization and hemagglutination inhibition assays. An antibody response was defined as a ≥4-fold titer increase from baseline at the first post-vaccine time point. Baseline A(H1N1) titers in the CAR-T cohorts were significantly lower compared to controls. Antibody responses to ≥1 vaccine strain occurred in 2 (29%) individuals before CAR-T-cell therapy; one individual maintained a response for >3 months post-CAR-T-cell therapy. Antibody responses to ≥1 vaccine strain occurred in 6 (40%) individuals vaccinated after CAR-T-cell therapy. An additional 2 (29%) and 6 (40%) individuals had ≥2-fold increases (at any time) in the pre- and post-CAR-T cohorts, respectively. There were no identified clinical or immunologic predictors of antibody responses. Neither severe hypogammaglobulinemia nor B-cell aplasia precluded antibody responses. These data support consideration for vaccination before and after CAR-T-cell therapy for influenza and other relevant pathogens such as SARS-CoV-2, irrespective of hypogammaglobulinemia or B-cell aplasia. Larger studies are needed to determine correlates of vaccine immunogenicity and durability in CAR-T-cell therapy recipients.

Key Points

Influenza vaccination was immunogenic pre- and post-CAR-T-cell therapy, despite hypogammaglobulinemia and B-cell aplasia.Vaccination with inactivated vaccines can be considered before CAR-T-cell therapy and in individuals with remission after therapy.