Abstract CT540: A phase 1 trial of cytokine-induced memory-like (CIML) natural killer (NK) cell therapy with IL-15 superagonist in advanced head and neck cancer: Part 1 results

Purpose: Outcomes for patients with recurrent, incurable or metastatic (R/M) squamous cell carcinoma of the head and neck (SCCHN) refractory to platinum and immunotherapy are poor. Cellular therapies are emerging treatments with potential utility in epithelial cancers. This proof-of-concept trial investigates an allogeneic cytokine-induced, memory-like (CIML) NK cell infusion with IL-15 superagonist (sa) after lymphodepleting (LD) chemotherapy in advanced SCCHN.

Patients and methods: This phase 1 single-center trial enrolled patients (pts) with R/M SCCHN regardless of human papillomavirus (HPV) status who had prior platinum and immunotherapy. Pts received LD fludarabine (25 mg/m2) and cyclophosphamide (60 mg/m2/kg) on days -6 to -2 prior to haploidentical CIML NK cell infusion on day 0 (5-10 x 106 viable cells/kg=dose level 0) followed by N-803 (IL-15sa, 15 mcg/kg subcutaneously) starting on day +1 every 21-days for 4-doses. Part 1 treated 3 pts at dose level 0; <2 DLTs triggered an additional 3 pts. Part 2 will treat an additional 6 pts with lead-in ipilimumab (day -7). Primary objective: safety, maximum tolerated dose of CIML NK cells. Secondary objectives: objective response rate, progression-free survival (PFS), overall survival (OS), and phenotypic expansion and function of adoptively transferred NK cells.

Results: From 9/8/20 to 9/7/21, 6 pts enrolled to Part 1. One DLT was observed at dose level 0. Among 6 pts, median age: 59; 5/6 (83%) were men; 5/6 (83%) had oropharyngeal primaries (4 HPV+) with a median 6 prior lines of therapy for R/M disease (range: 4-8). R/M disease sites: lung, bone, skin, liver. 5/6 (83%) had offspring donors. Grade (G) 3-4 hematologic adverse events were common (6/6, 100%). One patient died of G5 febrile neutropenia and infection. Median days hospitalized: 14 (range: 9-37). Mild cytokine release syndrome was observed in 5/6 (83%) (median peak ferritin: 2248, CRP: 168); 3/5 required anti-IL6 therapy; no neurotoxicity was noted. There were no dose adjustments or discontinuation of therapy. One (17%) partial response (PR) was observed lasting 6.5 months; 4 (67%) pts had stable disease (SD), and 1 (17%) had progression. Tumor regression was observed in 3/6 (50%) pts at day +30. At a median follow-up of 9.5 months, median PFS: 3.4 months (95%CI 2.6-6.5); median OS: 4.7 months (95%CI 3.4-11.8). CIML NK cells showed large expansion in the peripheral blood (PB) at day +7 in all pts; mean increase: 66% (6-fold; standard deviation [SD] 10.5), to constitute 80% (SD 12.1) of PB lymphocytes. In pts with tumor regression at day +30 compared to those without, the % of PB NK cells remained high at day +28 (mean: 78 vs. 11%). PB NK cells remained >50% at day +42 in the pt with a PR.

Conclusion: Allogeneic CIML NK cells can induce tumor regression associated with persistent CIML NK cell expansion among advanced SCCHN pts. In Part 1 we demonstrate safety and feasibility with the expected risks of LD conditioning. These findings have important implications for the development of cellular therapies in solid tumors.

Citation Format: Glenn J. Hanna, Kimberly Coleman, Grace Birch, Robert A. Redd, Alejandro Alonso, Samantha Bednarz, Heather Daley, Diego E. Hernandez Rodriguez, Kit L. Shaw, Robert I. Haddad, Ravindra Uppaluri, Jerome Ritz, Sarah Nikiforow, Robert J. Soiffer, Rizwan Romee. A phase 1 trial of cytokine-induced memory-like (CIML) natural killer (NK) cell therapy with IL-15 superagonist in advanced head and neck cancer: Part 1 results [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 CT540.

Expansion, persistence, and efficacy of donor memory-like NK cells infused for posttransplant relapse

BackgroundResponses to conventional donor lymphocyte infusion for postallogeneic hematopoietic cell transplantation (HCT) relapse are typically poor. Natural killer (NK) cell-based therapy is a promising modality to treat post-HCT relapse.MethodsWe initiated this ongoing phase I trial of adoptively transferred cytokine-induced memory-like (CIML) NK cells in patients with myeloid malignancies who relapsed after haploidentical HCT. All patients received a donor-derived NK cell dose of 5 to 10 million cells/kg after lymphodepleting chemotherapy, followed by systemic IL-2 for 7 doses. High-resolution profiling with mass cytometry and single-cell RNA sequencing characterized the expanding and persistent NK cell subpopulations in a longitudinal manner after infusion.ResultsIn the first 6 enrolled patients on the trial, infusion of CIML NK cells led to a rapid 10- to 50-fold in vivo expansion that was sustained over months. The infusion was well tolerated, with fever and pancytopenia as the most common adverse events. Expansion of NK cells was distinct from IL-2 effects on endogenous post-HCT NK cells, and not dependent on CMV viremia. Immunophenotypic and transcriptional profiling revealed a dynamic evolution of the activated CIML NK cell phenotype, superimposed on the natural variation in donor NK cell repertoires.ConclusionGiven their rapid expansion and long-term persistence in an immune-compatible environment, CIML NK cells serve as a promising platform for the treatment of posttransplant relapse of myeloid disease. Further characterization of their unique in vivo biology and interaction with both T cells and tumor targets will lead to improvements in cell-based immunotherapies.Trial RegistrationClinicalTrials.gov NCT04024761.FundingDunkin' Donuts, NIH/National Cancer Institute, and the Leukemia and Lymphoma Society.

The utility of the novel optimized HLH inflammatory (OHI) index for predicting the risk for mortality and causes of death in lymphoma

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Background: Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening inflammatory syndrome that may complicate hematologic malignancies (HM). We recently developed a simplified diagnostic and prognostic index termed the ‘optimized HLH inflammatory’ (OHI) index comprising the combined elevation of sCD25 ( > 3,900 U/mL) and serum ferritin ( > 1,000 ng/mL), which in HM patients both identifies HLH and predicts mortality more accurately than conventional criteria for HLH. In this study, we examined whether mortality in our cohort is directly related to progressive malignancy vs. HLH-associated causes in OHI+ and OHI- patients. Methods: We performed a multicenter, retrospective study of patients with newly diagnosed lymphoma from Israel, the USA, and Japan for whom sCD25 and ferritin levels were measured either as routine surveillance or during investigation for HLH and classified patients by their OHI status. The International Prognostic Index, International Prognostic Score, and Follicular Lymphoma International Prognostic Index were used to estimate the predicted prognosis of T/B cell non-Hodgkin’s lymphoma (NHL), Hodgkin’s lymphoma, and follicular lymphoma, respectively. Predicted five-year overall survival was calculated based on the relevant prognostic index and was compared between OHI+ and OHI- patients using the unpaired t-test. The actual survival at five years/last follow-up was recorded, as was the cause of death. The odds ratios (ORs) for observed vs. predicted mortality, and for HLH- vs. malignancy-related death were calculated using the Chi-square test. Results: 100 lymphoma patients were studied: 65% with B cell NHL, 18% with natural killer/ T cell lymphoma, 17% with Hodgkin’s lymphoma; 37 were OHI+, and 63 were OHI-. The disease-relevant international prognostic index-predicted five-year survival did not differ between OHI + and OHI- patients (a mean of 58% n OHI+ and 57% in OHI- p = 0.62). However, the observed five-year survival in OHI+ patients was lower (12%) than predicted, reflecting a mortality incidence that was four times higher than predicted by the relevant prognostic score (OR 3.9; CI 1.3-12.1). By contrast, OHI- patients had better survival (79%) than predicted by their prognostic scores (OR 0.15; CI 0.07-0.34). More than half of the OHI+ patients died from non-malignant causes (39% multi-organ dysfunction or HLH, 18% infection), while most OHI- patients (92%) died from progressive malignancy. The likelihood of dying from multi-organ dysfunction or HLH was 26 times higher in OHI+ vs. OHI- patients (OR 26.2; CI 4.1-286.7). Conclusions: OHI index status strongly correlated with mortality in patients with lymphoma within our cohort, and death in OHI+ patients was largely due to causes other than progressive malignancy. The OHI index appears to identify a harmful inflammatory state and deserves further prospective study.

Invasive Yeast Infection After Haploidentical Donor Hematopoietic Cell Transplantation Associated with Cytokine Release Syndrome

BACKGROUND

Use of haploidentical donor hematopoietic cell transplantation (haploHCT) has expanded but recent reports raise concern for increased rates of infectious complications. The incidence and risk factors for invasive fungal disease (IFD) after haploHCT have not been well elucidated.

OBJECTIVE

The objective of this study is to evaluate the incidence and risk factors for IFD after haploHCT. The identification of key risk factors will permit targeted prevention measures and may explain elevated risk for other infectious complications after haploHCT.

STUDY DESIGN

We performed a single-center retrospective study of all adults undergoing haploHCT between May 2011 and May 2021 (n=205). The 30-day and one-year cumulative incidence of proven or probable IFD and one-year non-relapse mortality (NRM) were assessed. Secondary analysis evaluated risk factors for invasive yeast infection (IYI) using univariate and multivariable Cox regression models.

RESULTS

Twenty-nine patients (14%) developed IFD following haploHCT. Nineteen (9.3%) developed IYI in the first year, 13 of which occurred early with a 30-day cumulative incidence of 6.3% (95% CI 2.9 - 9.6%) and increased NRM in patients with IYI (53.9% versus 10.9%). The majority of yeast isolates (17/20; 85%) were fluconazole susceptible. The incidence of IYI in the first 30 days after haploHCT was 10% among the 110 (54%) patients who developed cytokine release syndrome (CRS) and 21% among the 29 (14%) who received tocilizumab. On multivariable analysis, AML (HR 6.24; 1.66 - 23.37; p=0.007) and CRS (HR 4.65; 1.00 - 21.58; p=0.049) were associated with an increased risk of early IYI after haploHCT.

CONCLUSION

CRS after haploHCT is common and is associated with increased risk of early IYI. The identification of CRS as a risk factor for IYI raises questions about its potential association with other infections after haploHCT. Recognition of key risk factors for infection may permit individualized strategies for prevention and intervention and minimize potential side effects.

Phenotypic and functional characterization of the CD6-ALCAM T cell costimulatory pathway after allogeneic cell transplantation

CD6 is a co-stimulatory receptor expressed on T cells that binds activated leukocyte cell adhesion molecule (ALCAM), expressed on antigen presenting cells, epithelial and endothelial tissues. The CD6-ALCAM pathway plays an integral role in modulating T-cell activation, proliferation, and trafficking. In this study we examined expression of CD6 by reconstituting T cells in 95 patients after allogeneic cell transplantation and evaluated the effects of itolizumab, an anti-CD6 monoclonal antibody, on T-cell activation. CD6 T cells reconstituted early after transplant with CD4 regulatory T cells (Treg)-expressing lower levels of CD6 compared to conventional CD4 T cells (Tcon) and CD8 T cells. After onset of acute graft-versus-host disease (aGvHD), CD6 expression was further reduced in Treg and CD8 T cells compared to healthy donors, while no difference was observed for Tcon. ALCAM expression was highest in plasmacytoid dendritic cells (pDC), lowest in myeloid dendritic cells (mDC) and intermediate in monocytes and was generally increased after aGvHD onset. Itolizumab inhibited CD4 and CD8 T-cell activation and proliferation in preGvHD samples, but inhibition was less prominent in samples collected after aGvHD onset, especially for CD8 T cells. Functional studies showed that itolizumab did not mediate direct cytolytic activity or antibody-dependent cytotoxicity in vitro. However, itolizumab efficiently abrogated the costimulatory activity of ALCAM on T-cell proliferation, activation and maturation. Our results identify the CD6-ALCAM pathway as a potential target for aGvHD control and a phase I/II study using itolizumab as first line treatment in combination with steroids for patients with aGvHD is currently ongoing (clinicaltrials gov. Identifier: NCT03763318).

An improved index for diagnosis and mortality prediction in malignancy-associated hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening inflammatory syndrome that may complicate hematologic malignancies (HMs). The appropriateness of current criteria for diagnosing HLH in the context of HMs is unknown because they were developed for children with familial HLH (HLH-2004) or derived from adult patient cohorts in which HMs were underrepresented (HScore). Moreover, many features of these criteria may directly reflect the underlying HM rather than an abnormal inflammatory state. To improve and potentially simplify HLH diagnosis in patients with HMs, we studied an international cohort of 225 adult patients with various HMs both with and without HLH and for whom HLH-2004 criteria were available. Classification and regression tree and receiver-operating curve analyses were used to identify the most useful diagnostic and prognostic parameters and to optimize laboratory cutoff values. Combined elevation of soluble CD25 (>3900 U/mL) and ferritin (>1000 ng/mL) best identified HLH-2004-defining features (sensitivity, 84%; specificity, 81%). Moreover, this combination, which we term the optimized HLH inflammatory (OHI) index, was highly predictive of mortality (hazard ratio, 4.3; 95% confidence interval, 3.0-6.2) across diverse HMs. Furthermore, the OHI index identified a large group of patients with high mortality risk who were not defined as having HLH according to HLH-2004/HScore. Finally, the OHI index shows diagnostic and prognostic value when used for routine surveillance of patients with newly diagnosed HMs as well as those with clinically suspected HLH. Thus, we conclude that the OHI index identifies patients with HM and an inflammatory state associated with a high mortality risk and warrants further prospective validation.

Use of Transcranial Doppler as a Biomarker of CAR T Cell-Related Neurotoxicity

Background and Objectives

To examine the relationship between transcranial Doppler (TCD) mean flow velocity (MFV) and the severity and temporal onset of neurotoxicity after chimeric antigen receptor (CAR) T-cell therapy in patients with relapsed lymphoma.

Methods

We identified a cohort of 165 patients with relapsed or refractory B-cell lymphoma who received CAR T-cell therapy. TCDs were performed at baseline, treatment day 5, and throughout hospitalization based on development of neurologic symptoms. We assessed the percent change in velocity from baseline in each of the 6 major supratentorial arteries and the relationship of these values to development and timing of neurotoxicity.

Results

Our cohort was 30% female with an average age of 60 years. Of patients with TCDs performed, 63% developed neurotoxicity, and 32% had severe neurotoxicity. The median time of neurotoxicity onset was day 7. Higher maximum percent change in MFV across all vessels was significantly associated with likelihood of developing neurotoxicity (p = 0.0002) and associated with severe neurotoxicity (p = 0.0421). We found that with increased percent change in MFV, the strength of correlation between day of TCD velocity change and day of neurotoxicity onset increased. There was no single vessel in which increase in MFV was associated with neurotoxicity.

Discussion

Our study demonstrates an association between increase in TCD MFV and the development of neurotoxicity, as well as timing of neurotoxicity onset. We believe that TCD ultrasound may be used as a bedside functional biomarker in CAR T-cell patients and may guide immunologic interventions to manage toxicity in this complex patient group.

Donor Clonal Hematopoiesis and Recipient Outcomes After Transplantation

PURPOSE

Clonal hematopoiesis (CH) can be transmitted from a donor to a recipient during allogeneic hematopoietic cell transplantation. Exclusion of candidate donors with CH is controversial since its impact on recipient outcomes and graft alloimmune function is uncertain.

PATIENTS AND METHODS

We performed targeted error-corrected sequencing on samples from 1,727 donors age 40 years or older and assessed the effect of donor CH on recipient clinical outcomes. We measured long-term engraftment of 102 donor clones and cytokine levels in 256 recipients at 3 and 12 months after transplant.

RESULTS

CH was present in 22.5% of donors, with DNMT3A (14.6%) and TET2 (5.2%) mutations being most common; 85% of donor clones showed long-term engraftment in recipients after transplantation, including clones with a variant allele fraction < 0.01. DNMT3A-CH with a variant allele fraction ≥ 0.01, but not smaller clones, was associated with improved recipient overall (hazard ratio [HR], 0.79; P = .042) and progression-free survival (HR, 0.72; P = .003) after adjustment for significant clinical variables. In patients who received calcineurin-based graft-versus-host disease prophylaxis, donor DNMT3A-CH was associated with reduced relapse (subdistribution HR, 0.59; P = .014), increased chronic graft-versus-host disease (subdistribution HR, 1.36; P = .042), and higher interleukin-12p70 levels in recipients. No recipient of sole DNMT3A or TET2-CH developed donor cell leukemia (DCL). In seven of eight cases, DCL evolved from donor CH with rare TP53 or splicing factor mutations or from donors carrying germline DDX41 mutations.

CONCLUSION

Donor CH is closely associated with clinical outcomes in transplant recipients, with differential impact on graft alloimmune function and potential for leukemic transformation related to mutated gene and somatic clonal abundance. Donor DNMT3A-CH is associated with improved recipient survival because of reduced relapse risk and with an augmented network of inflammatory cytokines in recipients. Risk of DCL in allogeneic hematopoietic cell transplantation is driven by somatic myelodysplastic syndrome-associated mutations or germline predisposition in donors.

Donor Clonal Hematopoiesis and Recipient Outcomes After Transplantation

PURPOSE

Clonal hematopoiesis (CH) can be transmitted from a donor to a recipient during allogeneic hematopoietic cell transplantation. Exclusion of candidate donors with CH is controversial since its impact on recipient outcomes and graft alloimmune function is uncertain.

PATIENTS AND METHODS

We performed targeted error-corrected sequencing on samples from 1,727 donors age 40 years or older and assessed the effect of donor CH on recipient clinical outcomes. We measured long-term engraftment of 102 donor clones and cytokine levels in 256 recipients at 3 and 12 months after transplant.

RESULTS

CH was present in 22.5% of donors, with DNMT3A (14.6%) and TET2 (5.2%) mutations being most common; 85% of donor clones showed long-term engraftment in recipients after transplantation, including clones with a variant allele fraction < 0.01. DNMT3A-CH with a variant allele fraction ≥ 0.01, but not smaller clones, was associated with improved recipient overall (hazard ratio [HR], 0.79; P = .042) and progression-free survival (HR, 0.72; P = .003) after adjustment for significant clinical variables. In patients who received calcineurin-based graft-versus-host disease prophylaxis, donor DNMT3A-CH was associated with reduced relapse (subdistribution HR, 0.59; P = .014), increased chronic graft-versus-host disease (subdistribution HR, 1.36; P = .042), and higher interleukin-12p70 levels in recipients. No recipient of sole DNMT3A or TET2-CH developed donor cell leukemia (DCL). In seven of eight cases, DCL evolved from donor CH with rare TP53 or splicing factor mutations or from donors carrying germline DDX41 mutations.

CONCLUSION

Donor CH is closely associated with clinical outcomes in transplant recipients, with differential impact on graft alloimmune function and potential for leukemic transformation related to mutated gene and somatic clonal abundance. Donor DNMT3A-CH is associated with improved recipient survival because of reduced relapse risk and with an augmented network of inflammatory cytokines in recipients. Risk of DCL in allogeneic hematopoietic cell transplantation is driven by somatic myelodysplastic syndrome-associated mutations or germline predisposition in donors.

Adding venetoclax to fludarabine/busulfan RIC transplant for high-risk MDS and AML is feasible, safe, and active

Adding the selective BCL-2 inhibitor venetoclax to reduced-intensity conditioning chemotherapy (fludarabine and busulfan [FluBu2]) may enhance antileukemic cytotoxicity and thereby reduce the risk of posttransplant relapse. This phase 1 study investigated the recommended phase 2 dose (RP2D) of venetoclax, a BCL-2 selective inhibitor, when added to FluBu2 in adult patients with high-risk acute myeloid leukemia (AML), myelodysplastic syndromes (MDS), and MDS/myeloproliferative neoplasms (MPN) undergoing transplant. Patients received dose-escalated venetoclax (200-400 mg daily starting day -8 for 6-7 doses) in combination with fludarabine 30 mg/m2 per day for 4 doses and busulfan 0.8 mg/kg twice daily for 8 doses on day -5 to day -2 (FluBu2). Transplant related-toxicity was evaluated from the first venetoclax dose on day -8 to day 28. Twenty-two patients were treated. At study entry, 5 patients with MDS and MDS/MPN had 5% to 10% marrow blasts, and 18 (82%) of 22 had a persistent detectable mutation. Grade 3 adverse events included mucositis, diarrhea, and liver transaminitis (n = 3 each). Neutrophil/platelet recovery and acute/chronic graft-versus-host-disease rates were similar to those of standard FluBu2. No dose-limiting toxicities were observed. The RP2D of venetoclax was 400 mg daily for 7 doses. With a median follow-up of 14.7 months (range, 8.6-24.8 months), median overall survival was not reached, and progression-free survival was 12.2 months (95% confidence interval, 6.0-not estimable). In patients with high-risk AML, MDS, and MDS/MPN, adding venetoclax to FluBu2 was feasible and safe. To further address relapse risk, assessment of maintenance therapy after venetoclax plus FluBu2 transplant is ongoing. This study was registered at clinicaltrials.gov as #NCT03613532.

Abstract LB027: Tracking and decoding the antigen specificity of peripherally derived T cells that infiltrate into solid tumors in patients treated with an autologous T cell therapy, PRIME IL-15 (RPTR-147)

PRIME IL-15 (RPTR-147) is a novel non-genetically modified, autologous, multi-clonal T cell product loaded with an IL-15Fc nanogel. The product is derived from peripheral T cells that are primed and expanded against five tumor associated antigens (TAAs) known to be overexpressed in multiple different tumor types: PRAME, NY-ESO, SSX-2, WT-1 and Survivin.

17 patients with advanced or metastatic solid-tumor cancers were dosed in a Phase I dose escalation study. Where samples were available, we characterized the reactivity and specificity of the cellular product, and tracked its persistence and localization post administration in patients. We report cellular composition of the product, along with phenotype and TAA-specificity of the T cells. Antigen specificity of patient-derived product samples was determined by Repertoire Immune Medicines' proprietary DNA-barcoded pMHC tetramer platform (CIPHERTM), as well as by functional immunological methods including IFNg ELISpot and flow cytometry assessment of activation induced markers (AIM).

The CIPHER platform was used to identify TAA-specific CD8 T cell clonotypes, allowing decoding of T cell receptor (TCR) sequences and their cognate epitope/MHC. Distinct peptides binding from all five TAAs were observed across patients, and were presented across multiple HLA alleles. The phenotype of antigen-specific T cells identified via CIPHER was also assessed via single cell gene expression. Consistent with our previous studies on healthy donors, reactivity via IFNg ELISpot and AIM was also observed to all targeted TAAs.

TCR CDR3 sequences were used as molecular signatures of antigen-specific cells to track the product post administration. Bulk sequencing of TCRVβ was performed on tumors pre- and post-treatment. Several product-derived, TAA-specific CD8+ T cell clonotypes were observed in the post-, but not pre-treatment biopsies. We identified additional CD4+ and CD8+ clones that were enriched in the post-treatment biopsies, and some of these clonotypes were also enriched in the product. To de-orphan these tumor infiltrating lymphocytes (TIL) of interest, we cloned selected TIL TCRs to assess their reactivity using Repertoire Immune Medicines' proprietary MCR epitope screening platform.

In summary, characterization of antigen-specific T cells in the PRIME IL-15 product was performed by a variety of functional and molecular immune-based methods. Antigen specific T cell reactivities and clonotypes were identified in the peripheral repertoire. We confirmed that T cells were successfully expanded against TAAs and that these T cells do infiltrate the tumors as evidenced by bulk TCR sequencing of post-treatment tumor biopsies.

Citation Format: John David Pajerowski, William Gordon, Phil Bardwell, Christine McInnis, Ji Young Hwang, Tabasum Huseni, Parul Agnihotri, Josh Francis, Christina Tarr, Florian Renoux, Sebastian Heer, Nastassja Cerreghetti-Terraneo, Marisa Loi, Erika Hamilton, Sarah Nikiforow, George Blumenschein, Mihaela Christea, Keren Osman, Anthony Shields, Harriet Kluger, Franz-Josef Obermair, Daniel Pregibon, Jan Kisielow, Anthony Coyle, Mojca Skoberne. Tracking and decoding the antigen specificity of peripherally derived T cells that infiltrate into solid tumors in patients treated with an autologous T cell therapy, PRIME IL-15 (RPTR-147) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB027.

Clinical Predictors of Neurotoxicity After Chimeric Antigen Receptor T-Cell Therapy

Importance

Chimeric antigen receptor (CAR) T-cell therapy for relapsed or refractory hematologic malignant neoplasm causes severe neurologic adverse events ranging from encephalopathy and aphasia to cerebral edema and death. The cause of neurotoxicity is incompletely understood, and its unpredictability is a reason for prolonged hospitalization after CAR T-cell infusion.

Objective

To identify clinical and laboratory parameters predictive of neurotoxicity and to develop a prognostic score associated with its risk.

Design, Setting, and Participants

This single-center diagnostic/prognostic accuracy study was conducted at Brigham and Women's Hospital/Dana Farber Cancer Institute from April 2015 to February 2020. A consecutive sample of all patients undergoing CAR T-cell therapy with axicabtagene ciloleucel for relapsed or refractory lymphoma were assessed for inclusion (n = 213). Patients who had previously received CAR T cells or who were treated for mantle cell lymphoma were excluded (n = 9). Patients were followed up for a minimum of 30 days from the date of CAR T-cell infusion.

Main Outcomes and Measures

The primary outcomes were measures of performance (accuracy, sensitivity, specificity, area under the curve) of a diagnostic tool to predict the occurrence of CAR-associated neurotoxicity, as graded by the Common Terminology Criteria for Adverse Events criteria.

Results

Two hundred four patients (127 men [62.2%]; mean [SD] age, 60.0 [12.1] years) were included in the analysis, of which 126 (61.8%) comprised a derivation cohort and 78 (38.2%), an internal validation cohort. Seventy-three patients (57.9%) in the derivation cohort and 45 patients (57.7%) in the validation cohort experienced neurotoxicity. Clinical and laboratory values obtained early in admission were used to develop a multivariable score that can predict the subsequent development of neurotoxicity; when tested on an internal validation cohort, this score had an area under the curve of 74%, an accuracy of 77%, a sensitivity of 82%, and a specificity of 70% (positive:negative likelihood ratio, 2.71:0.26).

Conclusions and Relevance

The score developed in this study may help predict which patients are likely to experience CAR T-cell-associated neurotoxicity. The score can be used for triaging and resource allocation and may allow a large proportion of patients to be discharged from the hospital early.

Molecular and cellular features of CTLA-4 blockade for relapsed myeloid malignancies after transplantation

Relapsed myeloid disease after allogeneic stem cell transplantation (HSCT) remains largely incurable. We previously demonstrated the potent activity of immune checkpoint blockade in this clinical setting with ipilimumab or nivolumab. To define the molecular and cellular pathways by which CTLA-4 blockade with ipilimumab can reinvigorate an effective graft-versus-leukemia (GVL) response, we integrated transcriptomic analysis of leukemic biopsies with immunophenotypic profiling of matched peripheral blood samples collected from patients treated with ipilimumab following HSCT on the Experimental Therapeutics Clinical Trials Network 9204 trial. Response to ipilimumab was associated with transcriptomic evidence of increased local CD8+ T-cell infiltration and activation. Systemically, ipilimumab decreased naïve and increased memory T-cell populations and increased expression of markers of T-cell activation and costimulation such as PD-1, HLA-DR, and ICOS, irrespective of response. However, responding patients were characterized by higher turnover of T-cell receptor sequences in peripheral blood and showed increased expression of proinflammatory chemokines in plasma that was further amplified by ipilimumab. Altogether, these data highlight the compositional T-cell shifts and inflammatory pathways induced by ipilimumab both locally and systemically that associate with successful GVL outcomes. This trial was registered at www.clinicaltrials.gov as #NCT01822509.

A novel index using inflammatory markers improves the diagnosis of hemophagocytic lymphohistiocytosis in patients with hematologic malignancies

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Background: Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening inflammatory syndrome that may accompany hematologic malignancies (HM). The diagnosis of HLH in patients with HM (HM-HLH) is confounded by a number of factors: the most commonly used HLH-2004 diagnostic criteria are derived from studies in infants while the Hscore used in adults is not specific for HMs; moreover, most parameters in these scoring systems may reflect features of the underlying HM rather than HLH associated inflammation; and finally specific diagnostic cutoff values for laboratory abnormalities in HM-HLH have not been defined. We therefore conducted a study to optimize the HLH-2004 laboratory thresholds for the diagnosis of HM-HLH. Methods: A multi-center retrospective study in adult patients with HM in whom testing for HLH was performed. HM-HLH was defined as fulfillment of 5/8 HLH-2004 diagnostic criteria. We established the optimal diagnostic cutoff levels for HLH-2004 laboratory parameters using receiver operating curves (ROC) and combined the best performing parameters into a combined index, using binary logistic regression. We then created a clinical decision tree using a Classification and Regression Tree (CART) analysis with all available parameters, using cross validation. We also determined the prognostic value of our combined diagnostic tool. Results: 225 adults were analyzed (112 with HM-HLH per HLH-2004 and 113 with HM only). 35% of patients were evaluated for HLH routinely upon HM diagnosis. Soluble CD25 (sCD25) and ferritin best discriminated HM-HLH from HM, with an area under the curve (AUC) of 0.83 for each. ROC analysis demonstrated an optimal cutoff of > 4190 U/mL for sCD25 (sensitivity/specificity 91%/69%) and an optimal cutoff of > 2636 ng/ml for ferritin (sensitivity/specificity 64%/86%) for HM-HLH. We term the combination of elevated sCD25 and ferritin using optimized cutoff levels the ‘optimized HLH inflammatory’ (OHI) index. This OHI index was highly specific for the diagnosis of HM-HLH (specificity of 92%, sensitivity 79%). CART analysis demonstrated that OHI index positivity was sufficient to diagnose HM-HLH. In patients without a positive OHI index an Hscore > 168 and either splenomegaly or triglycerides > 279 ng/dL can still diagnose HM-HLH. By following this decision pathway, approximately 92% of patients were accurately classified based on HLH-2004. Furthermore, the OHI was better (odds ratio (OR) 7.9; 95% confidence interval (CI) 4.2-14.6) than Hscore >169 (OR 5.5; CI 3.9-9.6) and > 5/8 HLH-2004 (OR 5.3; CI 3-9.3) at predicting mortality at 1 year. Conclusions: The OHI index derived here is a simple tool that can accurately diagnose HLH and predict mortality in patients with hematologic malignancies. Some patients may not need full HLH workup before intervening with therapy that is HLH directed and not only malignancy directed.

Real-world evidence of axicabtagene ciloleucel (Axi-cel) for the treatment of large B-cell lymphoma (LBCL) in the United States (US)

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Background: Axi-cel is approved in the US for the treatment of adult patients with relapsed or refractory LBCL after 2 or more lines of systemic therapy. Post-market long term follow up study of commercial Axi-cel recipients using the Center for International Blood and Marrow Transplant Research was recently completed. Methods: From October 2017 to August 2020, 1,500 Axi-cel recipients from 79 centers were enrolled. Of these, 1001 patients with at least 6 months of follow-up were included in this analysis. Outcomes include complete and overall responses rates (CR and ORR), duration of response (DOR), progression-free and overall survival (PFS and OS), cytokine release syndrome (CRS) (Lee D 2014 and American Society for Transplantation and Cellular Therapy [ASTCT]), immune effector cell associated neurotoxicity syndrome (ICANS), hematologic recovery and subsequent neoplasm (SN). Subgroup analysis by sensitivity to therapy, defined as responsive to the last line of therapy prior to Axi-cel. Median follow-up was 12 months (range, 6-28 months). Results: The median age overall was 62 years, 37% were ≥ 65 years, 83% with Eastern Cooperative Oncology Group (ECOG) performance score 0-1, 28% with transformed lymphoma, 14% with high grade lymphoma, 29% with prior autologous transplant, and 66% with chemotherapy-resistant disease prior to Axi-cel. The median time from diagnosis to Axi-cel infusion was 15 months. Best ORR was 70% (CR 53%). Landmark analysis of patients in CR at 6 months post Axi-cel demonstrates a low number of subsequent progression/death events. With respect to outcomes for chemotherapy-sensitive disease versus resistant disease, the ORR, CR, 12-month PFS and OS were 78% vs. 66%, 60% vs. 48%, 55% (95% CI, 48-62%) vs. 40% (95% CI, 37-44%), and 70% (95% CI, 63-76%) vs. 54% (95% CI, 50-58%), respectively. CRS of any grade was reported in 83% of patients. Incidence of Grades ≥ 3 CRS was 10% according to Lee et al 2014, and 13% according to ASTCT Consensus Grading. Median time to any grade CRS was 4 days (range, 1-28 days), and 93% of CRS cases resolved with a median duration of 7 days (range, 1-121 days). ICANS were reported in 576 (57%) patients, grade >3 was 26%. The median time to onset of ICANS was 7 days (range, 1-82 days), and 86% resolved with a median duration of 9 days (range, 1 to 115 days). Twenty-nine patients (2.9%) reported SN: hematologic (N = 17), solid tumors (N = 12). Conclusions: This is the largest report on Axi-cel in the real-world setting and demonstrates consistent efficacy outcomes and further characterizes safety outcomes. Patients in CR at 6 months have sustained disease control with low number of relapse events. Although patients with therapy-sensitive disease experience better outcomes than patients with therapy-resistant, the overall outcomes on both groups of patients are favorable.

Phase 1 Study of CART-ddBCMA, a CAR-T therapy utilizing a novel synthetic binding domain, for the treatment of subjects with relapsed and refractory multiple myeloma

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Background: CART-ddBCMA is an autologous CAR-T cell therapy encoding a novel non-scFv synthetic binding domain targeting BCMA with a 4-1BB costimulatory motif and CD3-zeta T-cell activation domain. The novel binding domain is based on a computationally-derived triple-helix protein scaffold that is small (73 amino acids), stable, engineered to reduce immunogenicity, and can be modified to bind alternative targets. Methods: ARC-101 (NCT04155749), ARM 1 (CART-ddBCMA) is a Phase 1, multi-center, open-label, dose escalation trial enrolling subjects who have received ≥3 prior regimens, including proteasome inhibitor(s), immuno-modulatory agent(s), and anti-CD38 antibody, or are triple-refractory. Subjects undergo lymphodepletion with fludarabine and cyclophosphamide, then receive CART-ddBCMA as a single infusion. Planned dose levels are 100, 300, and up to 900 x 106 CAR+ T cells. The primary endpoint is incidence of adverse events (AEs), including dose-limiting toxicities (DLTs). Secondary endpoints include clinical response per IMWG criteria, MRD, DOR, PFS, OS, and CAR-T cell kinetics. Results: As of 29 Jan 2021, 10 subjects received CART-ddBCMA, 9 subjects were evaluable, and 1 subject was pending assessment. Median age was 66 years [min:max 54 to 75]. 6 subjects received 100 x 106 CAR+ T cells, and 4 subjects received 300 x 106 CAR+ T cells. Median CAR+ expression was 74.5% (min:max 61-87%) of total T cells. Of the evaluable subjects, median follow-up after cell infusion was 208 days (min:max 45 to 355+ days), 9/9 subjects were penta-refractory, 1 subject was also refractory to BCMA-directed ADC. 8/9 had high-risk cytogenetics (1 subject’s sample not evaluable), and 6/9 subjects had extramedullary disease. No DLTs were reported. Per ASTCT Consensus Grading (Lee et al, 2019), 8 subjects developed G1/2 CRS, 1 subject in the higher dose cohort developed G3 CRS that rapidly resolved with tocilizumab. 1 subject developed G2 ICANS which rapidly resolved with intervention. 7 subjects received tocilizumab; 3 received dexamethasone. ORR was 100% (9/9) per IMWG criteria including 4 sCR, 1 VGPR, and 4 PR. 1 subject with PR relapsed and was retreated. All other subjects have ongoing responses; observations included sFLC normalization and elimination of detectable bone marrow disease by Month 1. Ongoing responses for subjects not yet achieving CR continue to deepen. 7 subjects were evaluable by MRD of which 5 are MRD-negative, and 2 are pending results. CAR-T cell expansion, as measured by vector transgene copies per microgram genomic DNA was observed in all patients. Conclusions: Early efficacy results are encouraging, with 9/9 (100%) ORR and manageable toxicities. 8/9 responses are ongoing and responses continue to deepen. These data are encouraging in high-risk subjects with penta-refractory myeloma. Subjects continue to be enrolled and treated. Clinical trial information: NCT04155749.

Global Perspective on the Development of Genetically Modified Immune Cells for Cancer Therapy

Since the first genetically-engineered clinical trial was posted to clinicaltrials.gov in 2003 (NCT00019136), chimeric antigen receptor (CAR) and T-cell receptor (TCR) therapies have exhibited unprecedented growth. USA, China, and Europe have emerged as major sites of investigation as many new biotechnology and established pharmaceutical companies invest in this rapidly evolving field. Although initial studies focused primarily on CD19 as a target antigen, many novel targets are now being evaluated. Next-generation genetic constructs, starting materials, and manufacturing strategies are also being applied to enhance efficacy and safety and to treat solid tumors as well as hematologic malignancies. Fueled by dramatic clinical efficacy and recent regulatory approvals of CD19-targeted CAR cell therapies, the field of engineered cell therapeutics continues to expand. Here, we review all 745 genetically modified CAR and TCR clinical trials with anticipated accrual of over 28,000 patients posted to clinicaltrials.gov until 31st of December 2019. We analyze projected patient enrollment, geographic distribution and phase of studies, target antigens and diseases, current strategies for optimizing efficacy and safety, and trials expected to yield important clinical data in the coming 6-12 months.

COVID-19 and hematopoietic stem cell transplantation and immune effector cell therapy: a US cancer center experience

The novel coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), identified in late 2019 as the causative agent of COVID-19, was declared a pandemic by the World Health Organization on 11 March 2020. Widespread community transmission in the United States triggered a nationwide shutdown, raising major challenges for administration of hematopoietic stem cell transplant (HSCT) and chimeric antigen receptor (CAR)-T cell therapies, leading many centers to delay or cancel operations. We sought to assess the impact of the COVID-19 pandemic on operations and clinical outcomes for HSCT and CAR-T cellular therapies at the Dana-Farber Cancer Institute by reviewing administration and outcomes in 127 cell therapy patients treated during the initial COVID-19 surge: 62 adult allogeneic HSCT (allo-HSCT), 38 autologous HSCT (auto-HSCT), and 27 CAR-T patients. Outcomes were compared with 66 allo-HSCT, 43 auto-HSCT, and 33 CAR-T patients treated prior to the pandemic. A second control cohort was evaluated for HSCT groups to reflect seasonal variation in infections. Although there were changes in donor selection and screening as well as cryopreservation patterns of donor products, no differences were observed across groups in 100-day overall survival, progression-free survival, rates of non-COVID-19 infections, including hospital length of stay, neutrophil engraftment, graft failure, acute graft-versus-host disease in allo-HSCT patients, or cytokine release syndrome and neurotoxicity in CAR-T patients. No HSCT patients contracted COVID-19 between days 0 and 100. One CAR-T patient contracted COVID-19 at day +51 and died of the disease. Altogether, our data indicate that cellular therapies can be safely administered throughout the ongoing COVID-19 pandemic with appropriate safeguards.