Earlier corticosteroid use for adverse event management in patients receiving axicabtagene ciloleucel for large B-cell lymphoma

Axicabtagene ciloleucel (axi‐cel) is an autologous anti‐CD19 chimeric antigen receptor (CAR) T‐cell therapy approved for relapsed or refractory large B‐cell lymphoma (R/R LBCL). To reduce axi‐cel–related toxicity, several exploratory safety management cohorts were added to ZUMA‐1 (NCT02348216), the pivotal phase 1/2 study of axi‐cel in refractory LBCL. Cohort 4 evaluated the rates and severity of cytokine release syndrome (CRS) and neurologic events (NEs) with earlier corticosteroid and tocilizumab use. Primary endpoints were incidence and severity of CRS and NEs. Patients received 2 × 10⁶ anti‐CD19 CAR T cells/kg after conditioning chemotherapy. Forty‐one patients received axi‐cel. Incidences of any‐grade CRS and NEs were 93% and 61%, respectively (grade ≥ 3, 2% and 17%). There was no grade 4 or 5 CRS or NE. Despite earlier dosing, the cumulative cortisone‐equivalent corticosteroid dose in patients requiring corticosteroid therapy was lower than that reported in the pivotal ZUMA‐1 cohorts. With a median follow‐up of 14·8 months, objective and complete response rates were 73% and 51%, respectively, and 51% of treated patients were in ongoing response. Earlier and measured use of corticosteroids and/or tocilizumab has the potential to reduce the incidence of grade ≥ 3 CRS and NEs in patients with R/R LBCL receiving axi‐cel.

KTE-X19 for relapsed or refractory adult B-cell acute lymphoblastic leukaemia: phase 2 results of the single-arm, open-label, multicentre ZUMA-3 study

BACKGROUND

Despite treatment with novel therapies and allogeneic stem-cell transplant (allo-SCT) consolidation, outcomes in adult patients with relapsed or refractory B-precursor acute lymphoblastic leukaemia remain poor, underlining the need for more effective therapies.

METHODS

We report the pivotal phase 2 results of ZUMA-3, an international, multicentre, single-arm, open-label study evaluating the efficacy and safety of the autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy KTE-X19 in adult patients with relapsed or refractory B-precursor acute lymphoblastic leukaemia. Patients were enrolled at 25 sites in the USA, Canada, and Europe. Eligible patients were aged 18 years or older, with Eastern Cooperative Oncology Group performance status of 0-1, and morphological disease in the bone marrow (>5% blasts). After leukapheresis and conditioning chemotherapy, patients received a single KTE-X19 infusion (1 × 10⁶ CAR T cells per kg bodyweight). The primary endpoint was the rate of overall complete remission or complete remission with incomplete haematological recovery by central assessment. Duration of remission and relapse-free survival, overall survival, minimal residual disease (MRD) negativity rate, and allo-SCT rate were assessed as secondary endpoints. Efficacy and safety analyses were done in the treated population (all patients who received a dose of KTE-X19). This study is registered with ClinicalTrials.gov, NCT02614066.

FINDINGS

Between Oct 1, 2018, and Oct 9, 2019, 71 patients were enrolled and underwent leukapheresis. KTE-X19 was successfully manufactured for 65 (92%) patients and administered to 55 (77%). The median age of treated patients was 40 years (IQR 28-52). At the median follow-up of 16·4 months (13·8-19·6), 39 patients (71%; 95% CI 57-82, p<0·0001) had complete remission or complete remission with incomplete haematological recovery, with 31 (56%) patients reaching complete remission. Median duration of remission was 12·8 months (95% CI 8·7-not estimable), median relapse-free survival was 11·6 months (2·7-15·5), and median overall survival was 18·2 months (15·9-not estimable). Among responders, the median overall survival was not reached, and 38 (97%) patients had MRD negativity. Ten (18%) patients received allo-SCT consolidation after KTE-X19 infusion. The most common adverse events of grade 3 or higher were anaemia (27 [49%] patients) and pyrexia (20 [36%] patients). 14 (25%) patients had infections of grade 3 or higher. Two grade 5 KTE-X19-related events occurred (brain herniation and septic shock). Cytokine release syndrome of grade 3 or higher occurred in 13 (24%) patients and neurological events of grade 3 or higher occurred in 14 (25%) patients.

INTERPRETATION

KTE-X19 showed a high rate of complete remission or complete remission with incomplete haematological recovery in adult patients with relapsed or refractory B-precursor acute lymphoblastic leukaemia, with the median overall survival not reached in responding patients, and a manageable safety profile. These findings indicate that KTE-X19 has the potential to confer long-term clinical benefit to these patients.

FUNDING

Kite, a Gilead Company.

Prophylactic corticosteroid use in patients receiving axicabtagene ciloleucel for large B-cell lymphoma

ZUMA‐1 (NCT02348216) examined the safety and efficacy of axicabtagene ciloleucel (axi‐cel), an autologous CD19‐directed chimaeric antigen receptor (CAR)‐T cell therapy, in refractory large B‐cell lymphoma. To reduce treatment‐related toxicity, several exploratory safety management cohorts were added to ZUMA‐1. Specifically, cohort 6 investigated management of cytokine release syndrome (CRS) and neurologic events (NEs) with prophylactic corticosteroids and earlier corticosteroid and tocilizumab intervention. CRS and NE incidence and severity were primary end‐points. Following leukapheresis, patients could receive optional bridging therapy per investigator discretion. All patients received conditioning chemotherapy (days −5 through −3), 2 × 10⁶ CAR‐T cells/kg (day 0) and once‐daily oral dexamethasone [10 mg, day 0 (before axi‐cel) through day 2]. Forty patients received axi‐cel. CRS occurred in 80% of patients (all grade ≤2). Any grade and grade 3 or higher NEs occurred in 58% and 13% of patients respectively. Sixty‐eight per cent of patients did not experience CRS or NEs within 72 h of axi‐cel. With a median follow‐up of 8·9 months, objective and complete response rates were 95% and 80% respectively. Overall, prophylactic corticosteroids and earlier corticosteroid and/or tocilizumab intervention resulted in no grade 3 or higher CRS, a low rate of grade 3 or higher NEs and high response rates in this study population.

Abstract CT036: Axicabtagene ciloleucel (axi-cel) product attributes and immune biomarkers associated with clinical outcomes in patients (pts) with relapsed/refractory (R/R) indolent non-Hodgkin lymphoma (iNHL) in ZUMA-5

Background: ZUMA-5 is a registrational Phase 2 study of axi-cel anti-CD19 CAR T-cell therapy in pts with R/R iNHL (follicular lymphoma [FL] and marginal zone lymphoma [MZL]). With a 17.5-mo median follow-up (Jacobson et al. ASH 2020. #700), 92% of pts responded (76% complete response [CR] rate). Pts with FL had lower rates of Grade ≥3 neurologic events (NEs; 15%) than pts with MZL (41%). Peak levels of key serum biomarkers were associated with Grade ≥3 NEs in pts with FL. Here we describe axi-cel product attributes and pharmacologic characteristics associated with clinical outcomes in ZUMA-5. Methods: Associations among product attributes, blood levels of CAR T cells and biomarkers, as well as CD19 expression in tumor biopsies at relapse (13 samples evaluable from 21 relapsed pts) were analyzed with methods described in Neelapu et al. New Engl J Med. 2017; Locke et al. Blood Adv. 2020. Pts with FL (n=124) and MZL (n=22) treated with axi-cel were included (median follow-up, 17.5 mo). Results: In pts with FL, ongoing response was positively associated with number of total infused CCR7+CD45RA+ T cells (P=.0044) and peak CAR T-cell levels (P=.0212). The association was maintained for number of CCR7+CD45RA+ T cells (P=.0065) and peak CAR T-cell levels (P=.0184) relative to tumor burden. CR also associated positively with these characteristics relative to tumor burden (P=.0217; P=.0383). In addition, ongoing response positively associated with peak levels of immune-modulating factor IFN-γ, inflammatory markers IL-6, SAA and CRP; homeostatic marker IL-2, and chemokine CXCL10. Relapse post-axi-cel in pts with FL was positively associated with higher pretreatment levels of regulatory T cell-related chemokines CCL22/MDC and CCL17, immune-modulating factors IL-10 and IL-16, and inflammatory markers IL-2Rα and TNF-α. Numbers of total infused CCR7+CD45RA+ T cells and peak CAR T-cell levels positively associated with Grade ≥2 cytokine release syndrome (P=.0398; P&lt;.0001) and Grade ≥3 NEs (P=.0356; P=.0032) in pts with FL. Peak CAR T-cell levels were comparable in pts with FL and MZL. Compared with pts with MZL, pts with FL had numerically higher pretreatment levels of CCL17 and lower posttreatment levels of GM-CSF, IL-6, IL-10, IFN-γ, IL-2, CXCL10, and granzyme B. All evaluable tumor samples from pts with iNHL at relapse (12 FL; 1 MZL) retained CD19 expression. Conclusions: Results suggest that product composition and immune regulatory mechanisms, rather than target-related evasion, may influence the clinical activity of axi-cel in pts with FL. Differences in pre- and post-treatment levels of select disease and axi-cel-related biomarkers may contribute to differences in rates of severe NEs in pts with FL vs MZL.

Citation Format: Vicki Plaks, Justin Chou, Lovely Goyal, Wangshu Zhang, Shruti Salunkhe, Alison R. Sehgal, Julio C. Chavez, Sattva S. Neelapu, Caron A. Jacobson, Mauro P. Avanzi, John M. Rossi, Adrian Bot. Axicabtagene ciloleucel (axi-cel) product attributes and immune biomarkers associated with clinical outcomes in patients (pts) with relapsed/refractory (R/R) indolent non-Hodgkin lymphoma (iNHL) in ZUMA-5 [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 CT036.

Abstract CT166: Pretreatment (PreTx) immune cell phenotypes in peripheral blood associated with the tumor immune contexture, product attributes, and durable clinical efficacy in patients with large B-cell lymphoma (LBCL) treated with axicabtagene ciloleucel (axi-cel)

Background: Conventional prognostic factors for LBCL were not associated with outcomes in the pivotal ZUMA-1 study of axi-cel in relapsed LBCL (Neelapu et al. NEJM. 2017); however, other attributes like chimeric antigen receptor (CAR) T-cell fitness and composition (CCR7+CD45RA+ T cells), reduced preTx tumor burden, and immune tumor microenvironment (TME) with presence of activated CD8+PD-1+LAG-3+/-TIM-3- T cells were associated with efficacy (Locke et al. Blood Adv. 2020; Galon et al. ASCO 2020. #3022). Here, we evaluated preTx immune cell phenotypes in premanufacturing apheresis (premfg aph) material, comprising peripheral blood mononuclear cells, to determine associations with product attributes, immune TME features, and clinical efficacy in ZUMA-1. Methods: Evaluable samples from patients (pts) in Phase (Ph) 1 and Ph2 Cohorts (C) 1-3 were analyzed (NCT02348216; Ph1 and Ph2 C1+2, ≥2-y follow-up; C3, ≥6-mo follow-up). Memory T, myeloid, NK, NKT, and B cells in premfg aph material (n=101, excluding C3) were characterized by flow cytometry (FC). PreTx immune TME was analyzed by multiplex IHC (n=18) and gene expression analysis (n=30) as previously described (Rossi et al. AACR 2018. #LB-016; Galon et al. ASCO 2020. #3022). CAR T-cell fitness was analyzed by doubling time, viability during manufacturing, and product T-cell phenotypes by FC (n=145). Associations between these covariates, and with routine hematology tests, were performed by Spearman rank correlation or Wilcoxon tests. Effects on survival were assessed by Kaplan-Meier with optimized cutpoint selection. Results: The percentage (%) of naive (CCR7+CD45RA+) T helper (Th; CD4+CD127+CD25low) cells coexpressing CD27 and CD28 (median, 1%; range, 0.01%-15.8%; IQR, 0.3%-3.8%) in aph associated positively with axi-cel efficacy. The % of intermediate monocytes (IMs; CD14+CD16+; median, 1.8%; range, 0.003%-16.7%; IQR, 1%-3%) in aph associated negatively with efficacy. The % of circulating CD27+CD28+ naive Th cells associated positively with an enriched preTx immune TME T-cell signature, % CCR7+CD45RA+ product T cells, objective response rate, PFS, and OS. An increased % of IMs associated directly with negative predictive markers (preTx serum levels of LDH, IL-6, and CRP) and inversely with TME T-cell signature, PFS, and OS. The premfg ratio of CD27+CD28+ naive Th cells/IMs associated directly with CAR T-cell expansion and efficacy. Conclusions: This work points to a link between the pre-existing state of the immune system, reflected in premfg aph, and immune TME, as well as product attributes influencing axi-cel efficacy in LBCL. These data bear practical implications towards the development of predictive biomarkers for axi-cel efficacy. [JB and JC contributed equally.]

Citation Format: Justin Budka, Justin Chou, Vicki Plaks, Francesca Milletti, Zixing Wang, Frederick L. Locke, Sattva S. Neelapu, David B. Miklos, Caron A. Jacobson, Lazaros J. Lekakis, Yi Lin, Armin Ghobadi, Zahid Bashir, Nathalie Scholler, Jérôme Galon, John M. Rossi, Adrian Bot. Pretreatment (PreTx) immune cell phenotypes in peripheral blood associated with the tumor immune contexture, product attributes, and durable clinical efficacy in patients with large B-cell lymphoma (LBCL) treated with axicabtagene ciloleucel (axi-cel) [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 CT166.

A phase 1, multicenter study evaluating the safety and efficacy of KITE-585, an autologous anti-BCMA CAR T-cell therapy, in patients with relapsed/refractory multiple myeloma

Despite advances in treatment, most patients with multiple myeloma (MM) will relapse, and long-term survival remains poor. B-cell maturation antigen (BCMA) is an ideal therapeutic target as it is expressed throughout the disease course with normal tissue expression limited to plasma and some B-cell lineages. This phase 1, multicenter, first-in-human study evaluated the safety and efficacy of KITE-585, an autologous anti-BCMA chimeric antigen receptor (CAR) T-cell therapy, in patients with relapsed/refractory MM (RRMM). Key eligibility criteria included measurable MM and progression, defined by the International Myeloma Working Group Consensus Criteria within 60 days of the last treatment. Patients underwent leukapheresis and subsequently received a 3-day conditioning therapy regimen (cyclophosphamide [300 mg/m²/day] and fludarabine [30 mg/m²/day]). Patients then received a flat dose of 3 × 10⁷ to 1 × 10⁹ KITE-585 CAR T cells in a 3+3 dose-escalation design. The primary endpoint was incidence of adverse events (AEs) defined as dose-limiting toxicities (DLTs). Key secondary and exploratory endpoints included efficacy outcomes, incidence of AEs, levels of KITE-585 in blood, serum cytokines, and incidence of anti-BCMA CAR antibodies. Seventeen patients were enrolled, and 14 received KITE-585 with a median follow-up of 12.0 months. The median age of patients was 56 years, 41.2% had an Eastern Cooperative Oncology Group performance status of 1, 92.9% had baseline BCMA expression on plasma cells, and median number of prior therapies was 5.5. No patients experienced a DLT, all patients experienced ≥ 1 grade ≥ 3 treatment-emergent AE (TEAE), and no grade 5 TEAEs were observed. There were no grade ≥ 3 events of cytokine release syndrome, neurologic events, or infections; all were grade 1 or 2, and each occurred in 21.4% of patients. Among all patients infused with KITE-585, 1 patient who received 3 × 10⁷ anti-BCMA CAR T cells experienced a partial response. Median peak CAR T-cell expansion was low (0.98 cells/μL), as were median peak serum levels of CAR-associated cytokines, including interferon-γ (61.45 pg/mL) and interleukin-2 (0.9 pg/mL). KITE-585 demonstrated a manageable safety profile; however, the limited CAR T-cell expansion and associated lack of anti-tumor response in patients with RRMM treated with KITE-585 is consistent with the minimal CAR T-cell activity observed.

Favorable tumor immune microenvironment (TME) and robust chimeric antigen receptor (CAR) T-cell expansion may overcome tumor burden (TB) and promote durable efficacy with axicabtagene ciloleucel (axi-cel) in large B-cell lymphoma (LBCL)

7536

Background: Axi-cel is an autologous anti-CD19 CAR T-cell therapy approved for patients (pts) with relapsed/refractory LBCL after ≥2 prior systemic therapies. In the pivotal ZUMA-1 study, pts with high pretreatment (preTx) TB (estimated by sum of product diameters [SPD]) had lower peak CAR T-cell expansion normalized to TB and less frequent durable response rates vs pts with low TB ( < 30% vs > 60%, respectively; Blood Adv. 2020;4:3268). The number of CD8+ and CCR7+CD45RA+ product T cells infused and favorable immune contexture in preTx TME were also associated with axi-cel response ( Blood Adv. 2020;4:3268; Galon et al. ASCO 2020. #3022). As potential barriers to axi-cel efficacy are not fully elucidated, we systematically analyzed preTx TME characteristics, including myeloid-related biomarkers and product attributes, to identify such challenges in ZUMA-1 pts with high TB. Methods: Samples from evaluable pts in ZUMA-1 Phase (Ph) 1 and Ph2 Cohorts (C) 1–3 were analyzed (NCT02348216; Ph1 and Ph2 C1+2, ≥2-y follow-up; C3, ≥6-mo follow-up). PreTx immune TME was analyzed by multiplex immunohistochemistry (n = 18) and gene expression analysis (n = 30) as previously described (Rossi et al. AACR 2018. #LB-016; Galon et al. ASCO 2020. #3022). CAR T-cell product characteristics and other covariates were evaluated as previously described ( Blood Adv. 2020;4:3268). Correlative analyses of these covariates with clinical outcomes were performed by Wilcoxon or Kruskal-Wallis test. Median TB (by SPD) from ZUMA-1 Ph1 and Ph2 C1+2 was used as a cutoff for high ( > 3721 mm2) vs low (≤3721 mm2) TB. Durable response refers to pts in ongoing response at time of data cutoff. Results: PreTx immune TME features related to suppressive myeloid-related activity, most notably ARG2, TREM2, and IL-8 gene expression, were elevated in pts who failed to respond or relapsed without documented loss of CD19 expression. ARG2 and TREM2 levels in preTx biopsies were negatively associated with CD8+ T-cell density. Pts with high TB who achieved durable response had low preTx ARG2 and TREM2 levels in TME and enhanced CAR T-cell expansion after axi-cel compared to pts with high TB who relapsed. High ratio of T-cell to suppressive myeloid cell markers (T/M ratio) in preTx biopsies associated positively with CAR T-cell expansion (peak and peak normalized to TB) and durable response in pts with high TB. Conclusions: Axi-cel may overcome high TB in pts with a favorable immune TME alongside robust CAR T-cell expansion. Favorable immune TME is characterized by reduced suppressive myeloid cell activity (low ARG2 and TREM2 expression) and increased T/M ratio. These data suggest possible actionable strategies to overcome high TB in the context of CAR T-cell therapy. [JC and VP contributed equally] Clinical trial information: NCT02348216.

A Critical Role for Fas-Mediated Off-Target Tumor Killing in T-cell Immunotherapy

T cell-based therapies have induced cancer remissions, though most tumors ultimately progress, reflecting inherent or acquired resistance including antigen escape. Better understanding of how T cells eliminate tumors will help decipher resistance mechanisms. We used a CRISPR/Cas9 screen and identified a necessary role for Fas-FasL in antigen-specific T-cell killing. We also found that Fas-FasL mediated off-target "bystander" killing of antigen-negative tumor cells. This localized bystander cytotoxicity enhanced clearance of antigen-heterogeneous tumors in vivo, a finding that has not been shown previously. Fas-mediated on-target and bystander killing was reproduced in chimeric antigen receptor (CAR-T) and bispecific antibody T-cell models and was augmented by inhibiting regulators of Fas signaling. Tumoral FAS expression alone predicted survival of CAR-T-treated patients in a large clinical trial (NCT02348216). These data suggest strategies to prevent immune escape by targeting both the antigen expression of most tumor cells and the geography of antigen-loss variants. SIGNIFICANCE: This study demonstrates the first report of in vivo Fas-dependent bystander killing of antigen-negative tumors by T cells, a phenomenon that may be contributing to the high response rates of antigen-directed immunotherapies despite tumoral heterogeneity. Small molecules that target the Fas pathway may potentiate this mechanism to prevent cancer relapse.This article is highlighted in the In This Issue feature, p. 521.

Management of a patient with mantle cell lymphoma who developed severe neurotoxicity after chimeric antigen receptor T-cell therapy in ZUMA-2

Cerebral edema following chimeric antigen receptor (CAR) T-cell therapy can be fatal. ZUMA-2 is a pivotal phase 2, multicenter study evaluating KTE-X19, an autologous anti-CD19 CAR T-cell therapy, in relapsed/refractory mantle cell lymphoma. We describe a 65-year-old patient in ZUMA-2 who developed cerebral edema following CAR T-cell therapy and had complete recovery after multimodality clinical intervention including rabbit antithymocyte globulin (ATG). Biomarker results show early and robust CAR T-cell expansion and related induction of inflammatory cytokines, followed by rapid declines in CAR T-cell and proinflammatory cytokine levels after ATG administration. This clinical profile highlights a potential relevance of ATG in treating severe CAR T-cell-related neurotoxicity.

Abstract CT055: Phase 1/2 primary analysis of ZUMA-6: Axicabtagene ciloleucel (Axi-Cel) in combination With atezolizumab (Atezo) for the treatment of patients (Pts) with refractory diffuse large B cell lymphoma (DLBCL)

Background: Axi-cel is a US and EU-approved autologous anti-CD19 chimeric antigen receptor (CAR) T cell therapy for the treatment of adult relapsed/refractory LBCL after ≥ 2 prior lines of therapy. In ZUMA-1, the objective response rate (ORR) was 83% (58% complete response [CR] rate; Locke et al. Lancet Oncol. 2019). As checkpoint proteins (eg, PD-1, PD-L1) have been shown to be upregulated after CAR T cell infusion (Perez et al. ASH 2015. #2042; Galon et al. ASCO 2017. #3025; Neelapu et al. ASH 2017. #578; Arihara et al. SITC 2019. #P210), ZUMA-6 examined outcomes of axi-cel combined with the anti-PD-L1 antibody atezo (NCT02926833). Methods: Adult pts (≥18 y) with refractory DLBCL who received prior CD20-targeting and anthracycline-containing regimen, had ECOG ≤ 1, and had adequate bone marrow and organ function were eligible. Pts received conditioning (fludarabine 30 mg/m2/d + cyclophosphamide 500 mg/m2/d for 3 days) followed by a targeted 2 × 106 CAR T cells/kg. In Phase 1, atezo was given at 1200 mg every 21 days for 4 doses starting on Day 21, 14, and 1 post-axi-cel infusion for Cohorts 1, 2, and 3, respectively. Given Phase 1 results, pts received the Cohort 3 atezo (Day +1) dosing schedule in Phase 2. The primary endpoint was incidence of dose-limiting toxicities for Phase 1 and CR rate for Phase 2. Secondary endpoints included adverse events (AEs), response, and CAR T cell levels. Pooled data are reported for Phase 1 Cohort 3 and Phase 2 pts. Results: As of 2/21/19, 28 pts received axi-cel and ≥ 1 atezo dose; 18/28 pts received all 4 atezo doses. Median age was 58 y (range, 42 - 71). Most pts (86%) had received ≥ 2 prior therapies (4 had primary refractory disease), and 46% had an IPI score of 3 or 4. All pts experienced ≥ 1 AE (86% Grade [Gr] ≥ 3). There was 1 Gr 5 AE of multiple organ dysfunction syndrome unrelated to axi-cel or atezo. Gr ≥ 3 CRS occurred in 4% of pts, and Gr ≥ 3 neurologic events (NEs) occurred in 29%. With a median follow-up of 10.2 mo, the best ORR was 75% (46% CR rate); 46% of pts were in ongoing response. Median DOR, PFS, and OS were not reached; KM estimated 6-mo rates were 62%, 50%, and 71%, respectively. Median peak CAR T cell levels were similar in ZUMA-6 and ZUMA-1 (ZUMA-6: 37 cells/µL [range, 0.07 - 196]; ZUMA-1: 32 cells/µL [range, 1 - 1513]). Median CAR T cell expansion as measured by area under the curve in the first 28 days was also similar (ZUMA-6: 497 cells/µL × days [range, 0.002 - 2222]; ZUMA-1: 357 cells/µL × days [range, 5 - 11,507]). Levels of key cytokines, including those related to CRS and/or NEs, will be presented. Conclusions: PD-L1 blockade with atezo after axi-cel has a manageable safety profile, consistent with that observed in ZUMA-1, with no significant evidence of increased incidence of AEs. Efficacy outcomes and CAR T cell level results of axi-cel combined with atezo were similar to those of pts treated with axi-cel alone.

Citation Format: Caron A. Jacobson, Jason R. Westin, David B. Miklos, Alex F. Herrera, Jennifer Lee, Judy Seng, John M. Rossi, Jennifer Sun, Jinghui Dong, Zachary J. Roberts, Remus Vezan, Mauro P. Avanzi, Frederick L. Locke. Phase 1/2 primary analysis of ZUMA-6: Axicabtagene ciloleucel (Axi-Cel) in combination With atezolizumab (Atezo) for the treatment of patients (Pts) with refractory diffuse large B cell lymphoma (DLBCL) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT055.

Tumor microenvironment associated with increased pretreatment density of activated PD-1+ LAG-3+/− TIM-3− CD8+ T cells facilitates clinical response to axicabtagene ciloleucel (axi-cel) in patients (pts) with large B-cell lymphoma

3022

Background: Axi-cel is a US and EU-approved autologous anti-CD19 chimeric antigen receptor (CAR) T cell therapy for pts with relapsed/refractory large B cell lymphoma after ≥ 2 prior therapies. In ZUMA-1 (NCT02348216), the objective response rate was 83% (58% complete response rate; Locke et al. Lancet Oncol. 2019). T cell-related biology (Immunosign 21; Immunoscore) measured pretreatment in the tumor microenvironment (TME) was associated with response to axi-cel (Rossi et al. AACR 2018. #LB-016; Rossi et al. AACR 2019. #CT153). This expanded analysis characterized the pretreatment TME immune contexture and examined associations between immune cell subsets and response. Methods: In ZUMA-1, pts received axi-cel at a target dose of 2.0 × 106 CAR T cells/kg. Archival pretreatment tumor biopsy samples were analyzed by multiplex immunohistochemistry (Brightplex). Two panels were developed and applied to assess T cell (CD3, CD8, FoxP3, PD-1, LAG-3, TIM-3) and myeloid cell (CD11b, CD14, CD15, LOX1, S100A9, CD68) subsets (n = 14 total). The association between T cell and myeloid cell subset density, prespecified immune scores (Immunosign 21; Immunoscore), and objective response was evaluated. T test values were based on Brightplex analysis. Results: Pretreatment tumor biopsy samples from 18 pts were analyzed (14 objective responders and 4 nonresponders). The pretreatment TME comprised all major myeloid and T cell subsets, with diverse distribution across samples analyzed. The median TME density of monocytes (CD11b+ CD15− CD14+; 1215 cells/mm2) and macrophages (CD68+; 530 cells/mm2) was greater than that of the total CD8+ T cell subset (312 cells/mm2). The pretreatment Immunosign 21 and Immunoscore scores associated positively with the density of all major T cell subsets and some myeloid subsets. The density of activated CD8+ T cells (PD-1+ LAG-3+/− TIM-3−) was most significantly associated with clinical response versus other T cell subsets. The density of nonactivated CD8+ T cells (PD-1− LAG-3− TIM-3−) and exhausted CD8+ T cells (PD-1+ LAG-3+ TIM-3+) were not significantly associated with response. Additional characterization of the immune contexture and correlative analysis of cell subsets will be presented. Conclusions: These results suggest that a TME associated with increased density of activated PD-1+ LAG-3+/− TIM-3− CD8+ T cells, measurable pretreatment, facilitates clinical response in pts post–axi-cel.

Product characteristics and pharmacological profile of KTE-X19 in patients (pts) with relapsed/refractory (R/R) mantle cell lymphoma (MCL) in the phase II registrational ZUMA-2 trial

3023

Background: ZUMA-2 is a Phase 2 study evaluating KTE-X19, an autologous anti-CD19 CAR T cell therapy, in pts with R/R MCL (1 – 5 prior therapies, including a BTK inhibitor). In the primary efficacy analysis of ZUMA-2 (N = 60), the objective response rate was 93% (67% complete responses) and was generally comparable among high risk pts (Wang et al. ASH 2019 #754). CAR T cell levels in blood were associated with objective response (including minimal residual disease [MRD] negativity) and toxicity. Here, we describe a comparative analysis of KTE-X19 pharmacology profile in higher vs lower risk pts in ZUMA-2. Methods: Product attributes, CAR T cell and serum cytokine levels in blood, and their associations with clinical outcomes, were analyzed using previously described methods (Locke et al. Mol Ther 2017). MRD (10−5 sensitivity) was assessed by next-generation sequencing. Pharmacology data are reported for all 68 pts treated with KTE-X19 (2 × 106 cells/kg). Results: Manufactured KTE-X19 products showed a slight bias to CD8 and effector memory/effector phenotype. Median CD4/CD8 ratio was 0.7 (range, 0.04 – 3.7); T cell phenotypes included naive (median, 24.5%; range, 0.3 – 80.7), central memory (median, 12.8%; range, 2.3 – 51.6), effector memory (median, 24.5% (range, 0.8 – 70.3) and effector (median, 28.7%; range, 2.8 – 65.2). MRD negative (n = 24/29) vs positive pts (n = 5/29) at 1 mo post KTE-X19 had increased median cytokine levels, including IL-15, IL-2, IFN-γ, IL-10, and IL-6, peaking in serum within 7 days post treatment. Pts who were MRD negative by 1 mo post treatment also had increased median peak levels of Granzyme B and soluble PD-L1. Six pts developed Grade 4 neurologic events (NE), including 1 cerebral edema case; 3 had concurrent Grade 4 cytokine release syndrome. These pts had higher peak cytokine levels vs pts without Grade 4 NE, with lack of reversion to baseline by Day 28 of serum IL-6 and sVCAM-1. Peak CAR T cell in blood and serum cytokine levels were generally comparable in higher vs lower risk pts defined as TP53 mutated (n = 6/36) vs unmutated (n = 30/36), or high vs low Ki-67 proliferation index (PI; ≥ 30% [n = 40/49] and < 30% [n = 9/49]), consistent with the comparable clinical efficacy of KTE-X19 in these subgroups. Conclusions: PD profile of KTE-X19 associated with efficacy (MRD status at 1 mo) and treatment-related NE. In contrast to approved therapies, KTE-X19 showed comparable pharmacology and clinical outcomes in pts with higher vs lower risk MCL defined by TP53 mutation or Ki-67 PI. Clinical trial information: NCT02601313 .

Retreatment (reTx) of patients (pts) with refractory large B-cell lymphoma with axicabtagene ciloleucel (axi-cel) in ZUMA-1

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Background: Axi-cel, an autologous anti-CD19 chimeric antigen receptor (CAR) T cell therapy, is approved in the US and EU for pts with relapsed/refractory large B cell lymphoma after ≥ 2 prior therapies. In the ZUMA-1 pivotal study (NCT02348216), the objective response rate (ORR) was 83% (58% complete response [CR] rate; Locke et al. Lancet Oncol. 2019). While axi-cel has demonstrated durable responses in a subset of pts, approximately half of all responders relapsed, and little is known on the viability of reTx with CAR T cell therapy. Here we report outcomes of pts retreated with axi-cel in ZUMA-1. Methods: Pts with progressive disease (PD) were eligible for reTx if there was no evidence of CD19 loss by local review, and if during 1st Tx they did not experience any dose-limiting toxicities, as defined in Phase 1, or comparable toxicities in Phase 2. Pts received the same regimen at reTx as at 1st Tx: 2 × 106 CAR T cells/kg after conditioning chemotherapy. Results: Thirteen pts in Cohorts 1 – 4 received axi-cel reTx. Prior to 1st Tx, most pts (69%) had an IPI score 3-4, 85% had disease stage 3-4, and the median number of prior regimens was 3 (range, 2 – 6). At first Tx, 6 pts achieved a CR, 6 achieved partial response (PR), and 1 pt had stable disease (SD) prior to PD. Median duration of first response was 96 days (range, 56 – 274). There was no Grade ≥ 3 cytokine release syndrome (CRS; 6 pts each had Grade 1 and 2). There were no Grade 4 or 5 neurologic events (NEs; 2 pts had Grade 1, 1 had Grade 2, and 7 had Grade 3). Upon reTx, 54% of pts achieved response (4 CR, 3 PR). Response to reTx was more common among pts who achieved CR at 1st Tx (83%; 4/6 CR, 1 PR, 1 SD) than in pts who achieved PR at 1st Tx (33%; 2/6 PR, 1 SD, 3 PD), and no response was observed in the pt with SD at 1st Tx. Median duration of response at reTx was 81 days (range, 1 – 225+). Response with reTx was longer than that with 1st Tx for 2 pts. One pt remains in response 255 days post-reTx. Comparable rates of CRS were observed with reTx as with 1st Tx. Compared with 1st Tx, fewer pts experienced NEs with reTx, and those that did occur were of lower grade: 23% (3 of 13 pts) had Grade 3; 23% (3 of 13 pts) had Grade 1, and 8% (1 of 13 pts) had Grade 2. Peak CAR T cell expansion was lower upon reTx vs 1st Tx (median, 4.3 vs 66.1 CAR gene-marked cells/µL blood). Conclusions: Based on this limited sample size, reTx with axi-cel may have clinical efficacy, although transient, in some pts, especially those who achieve CR with 1st Tx. CAR T cell expansion and severe CRS and NEs may be attenuated at reTx. Further studies with additional pts are needed to confirm these results. Clinical trial information: NCT02348216 .

KTE-X19 CAR T-Cell Therapy in Relapsed or Refractory Mantle-Cell Lymphoma

BACKGROUND

Patients with relapsed or refractory mantle-cell lymphoma who have disease progression during or after the receipt of Bruton's tyrosine kinase (BTK) inhibitor therapy have a poor prognosis. KTE-X19, an anti-CD19 chimeric antigen receptor (CAR) T-cell therapy, may have benefit in patients with relapsed or refractory mantle-cell lymphoma.

METHODS

In a multicenter, phase 2 trial, we evaluated KTE-X19 in patients with relapsed or refractory mantle-cell lymphoma. Patients had disease that had relapsed or was refractory after the receipt of up to five previous therapies; all patients had to have received BTK inhibitor therapy previously. Patients underwent leukapheresis and optional bridging therapy, followed by conditioning chemotherapy and a single infusion of KTE-X19 at a dose of 2×10⁶ CAR T cells per kilogram of body weight. The primary end point was the percentage of patients with an objective response (complete or partial response) as assessed by an independent radiologic review committee according to the Lugano classification. Per the protocol, the primary efficacy analysis was to be conducted after 60 patients had been treated and followed for 7 months.

RESULTS

A total of 74 patients were enrolled. KTE-X19 was manufactured for 71 patients and administered to 68. The primary efficacy analysis showed that 93% (95% confidence interval [CI], 84 to 98) of the 60 patients in the primary efficacy analysis had an objective response; 67% (95% CI, 53 to 78) had a complete response. In an intention-to-treat analysis involving all 74 patients, 85% had an objective response; 59% had a complete response. At a median follow-up of 12.3 months (range, 7.0 to 32.3), 57% of the 60 patients in the primary efficacy analysis were in remission. At 12 months, the estimated progression-free survival and overall survival were 61% and 83%, respectively. Common adverse events of grade 3 or higher were cytopenias (in 94% of the patients) and infections (in 32%). Grade 3 or higher cytokine release syndrome and neurologic events occurred in 15% and 31% of patients, respectively; none were fatal. Two grade 5 infectious adverse events occurred.

CONCLUSIONS

KTE-X19 induced durable remissions in a majority of patients with relapsed or refractory mantle-cell lymphoma. The therapy led to serious and life-threatening toxic effects that were consistent with those reported with other CAR T-cell therapies. (Funded by Kite, a Gilead company; ZUMA-2 ClinicalTrials.gov number, NCT02601313.).

Application of the Johnson-Cook plasticity model in the finite element simulations of the nanoindentation of the cortical bone

The mechanical behavior of the cortical bone in nanoindentation is a complicated mechanical problem. The finite element analysis has commonly been assumed to be the most appropriate approach to this issue. One significant problem in nanoindentation modeling of the elastic-plastic materials is pile-up deformation, which is not observed in cortical bone nanoindentation testing. This phenomenon depends on the work-hardening of materials; it doesn't occur for work-hardening materials, which suggests that the cortical bone could be considered as a work-hardening material. Furthermore, in a recent study [59], a plastic hardening until failure was observed on the micro-scale of a dry ovine osteonal bone samples subjected to micropillar compression. The purpose of the current study was to apply an isotropic hardening model in the finite element simulations of the nanoindentation of the cortical bone to predict its mechanical behavior. The Johnson-Cook (JC) model was chosen as the constitutive model. The finite element modeling in combination with numerical optimization was used to identify the unknown material constants and then the finite element solutions were compared to the experimental results. A good agreement of the numerical curves with the target loading curves was found and no pile-up was predicted. A Design Of Experiments (DOE) approach was performed to evaluate the linear effects of the material constants on the mechanical response of the material. The strain hardening modulus and the strain hardening exponent were the most influential parameters. While a positive effect was noticed with the Young's modulus, the initial yield stress and the strain hardening modulus, an opposite effect was found with the Poisson's ratio and the strain hardening exponent. Finally, the JC model showed a good capability to describe the elastoplastic behavior of the cortical bone.

Outcomes of patients (pts) ≥ 65 years of age in ZUMA-1, a pivotal phase 1/2 study of axicabtagene ciloleucel (axi-cel) in refractory large B-cell lymphoma (LBCL)

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Background: Axi-cel is a US FDA-approved, autologous anti-CD19 chimeric antigen receptor (CAR) T cell therapy for the treatment of pts with relapsed or refractory LBCL with ≥ 2 prior systemic therapies. In the 2-y follow-up of ZUMA-1, the objective response rate (ORR) was 83% with a complete response (CR) rate of 58%, and 39% of pts were in ongoing response (Locke et al. Lancet Oncol. 2019). Here we report efficacy and safety outcomes by age. Methods: Eligible pts with refractory LBCL underwent leukapheresis and conditioning chemotherapy followed by a target dose of 2 × 106 anti-CD19 CAR T cells/kg. The Phase 2 primary endpoint was investigator-assessed ORR. Additional key endpoints were adverse events (AEs), overall survival (OS), and levels of CAR gene-marked cells in peripheral blood. Efficacy was evaluated for Phase 2 pts; safety was evaluated for all treated pts (Phases 1 and 2). Pts were analyzed by ≥ 65 y vs < 65 y of age. Results: As of 8/11/2018, 108 pts were treated. Pts ≥ 65 y (n = 27) vs < 65 y (n = 81) had a median age of 69 y vs 55 y, respectively, were 81% vs 63% male, 70% vs 36% had an IPI score 3-4, 59% vs 57% had ECOG 1, 67% vs 72% had ≥ 3 prior therapies, and median tumor burdens were 3790 mm2 vs 3574 mm2. Median follow-up was 27.1 mo for Phase 2 pts (n = 101). The ORR for pts ≥ 65 y (n = 24) and < 65 y (n = 77) was 92% and 81% (CR rate 75% and 53%), respectively, with ongoing responses in 42% and 38% of pts (ongoing CR 42% and 35%). The 24-mo OS rate was 54% for pts ≥ 65 y and 49% for pts < 65 y. Most pts experienced Grade ≥ 3 AEs (100% of pts ≥ 65 y; 98% of pts < 65 y), and 4% of each group (1/27 pts ≥ 65 y and 3/81 pts < 65 y) died due to AEs as previously reported. Grade ≥ 3 neurologic events and cytokine release syndrome occurred in 44% vs 28% and 7% vs 12% of pts ≥ 65 y vs < 65 y, respectively. CAR T cell expansion by peak level (43 vs 35 cells/μl) or area under the curve (562 vs 448 d × cells/μl) was similar in pts ≥ 65 y vs < 65 y, respectively. Conclusions: The 2-y follow-up of ZUMA-1 demonstrates that axi-cel can induce high rates of durable responses with a manageable safety profile for pts ≥ and < 65 y. Axi-cel offers substantial clinical benefit for older pts with refractory LBCL who otherwise have limited treatment options. Clinical trial information: NCT02348216.

Long-term safety and activity of axicabtagene ciloleucel in refractory large B-cell lymphoma (ZUMA-1): a single-arm, multicentre, phase 1-2 trial

BACKGROUND

Axicabtagene ciloleucel is an autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy. In the previous analysis of the ZUMA-1 registrational study, with a median follow-up of 15·4 months (IQR 13·7-17·3), 89 (82%) of 108 assessable patients with refractory large B-cell lymphoma treated with axicabtagene ciloleucel achieved an objective response, and complete responses were noted in 63 (58%) patients. Here we report long-term activity and safety outcomes of the ZUMA-1 study.

METHODS

ZUMA-1 is a single-arm, multicentre, registrational trial at 22 sites in the USA and Israel. Eligible patients were aged 18 years or older, and had histologically confirmed large B-cell lymphoma-including diffuse large B-cell lymphoma, primary mediastinal B-cell lymphoma, and transformed follicular lymphoma-according to the 2008 WHO Classification of Tumors of Hematopoietic and Lymphoid Tissue; refractory disease or relapsed after autologous stem-cell transplantation; an Eastern Cooperative Oncology Group performance status of 0 or 1; and had previously received an anti-CD20 monoclonal antibody containing-regimen and an anthracycline-containing chemotherapy. Participants received one dose of axicabtagene ciloleucel on day 0 at a target dose of 2 × 10⁶ CAR T cells per kg of bodyweight after conditioning chemotherapy with intravenous fludarabine (30 mg/m² body-surface area) and cyclophosphamide (500 mg/m² body-surface area) on days -5, -4, and -3. The primary endpoints were safety for phase 1 and the proportion of patients achieving an objective response for phase 2, and key secondary endpoints were overall survival, progression-free survival, and duration of response. Pre-planned activity and safety analyses were done per protocol. ZUMA-1 is registered with ClinicalTrials.gov, number NCT02348216. Although the registrational cohorts are closed, the trial remains open, and recruitment to extension cohorts with alternative endpoints is underway.

FINDINGS

Between May 19, 2015, and Sept 15, 2016, 119 patients were enrolled and 108 received axicabtagene ciloleucel across phases 1 and 2. As of the cutoff date of Aug 11, 2018, 101 patients assessable for activity in phase 2 were followed up for a median of 27·1 months (IQR 25·7-28·8), 84 (83%) had an objective response, and 59 (58%) had a complete response. The median duration of response was 11·1 months (4·2-not estimable). The median overall survival was not reached (12·8-not estimable), and the median progression-free survival was 5·9 months (95% CI 3·3-15·0). 52 (48%) of 108 patients assessable for safety in phases 1 and 2 had grade 3 or worse serious adverse events. Grade 3 or worse cytokine release syndrome occurred in 12 (11%) patients, and grade 3 or worse neurological events in 35 (32%). Since the previous analysis at 1 year, additional serious adverse events were reported in four patients (grade 3 mental status changes, grade 4 myelodysplastic syndrome, grade 3 lung infection, and two episodes of grade 3 bacteraemia), none of which were judged to be treatment related. Two treatment-related deaths (due to haemophagocytic lymphohistiocytosis and cardiac arrest) were previously reported, but no new treatment-related deaths occurred during the additional follow-up.

INTERPRETATION

These 2-year follow-up data from ZUMA-1 suggest that axicabtagene ciloleucel can induce durable responses and a median overall survival of greater than 2 years, and has a manageable long-term safety profile in patients with relapsed or refractory large B-cell lymphoma.

FUNDING

Kite and the Leukemia & Lymphoma Society Therapy Acceleration Program.

Abstract LB-016: Characteristics of the pretreatment tumor microenvironment may influence clinical response in patients with refractory large B cell lymphoma treated with axicabtagene ciloleucel (axi-cel) in the pivotal ZUMA-1

Introduction: Axicabtagene ciloleucel (axi-cel) is an autologous anti-CD19 CAR T cell therapy approved by the US Food and Drug Administration for patients with relapsed or refractory large B cell lymphoma with ≥2 prior systemic therapies. Results from the primary analysis of ZUMA-1 demonstrated an objective response rate of 82%, with 54% complete responses (Neelapu & Locke et al. N Engl J Med. 2017). Grade ≥3 cytokine release syndrome and neurologic events occurred at 13% and 28%, respectively, and were generally reversible. Building on previous reports of CAR treatment-related tumor microenvironment (TME) changes (Galon et al. ASCO 2017. #3025), here, we examine associations between the pretreatment TME and clinical outcomes.

Methods: Patients received axi-cel (target dose, 2.0 × 106 cells/kg) in phases 1 and 2 of ZUMA-1 (NCT02348216). Baseline tumor biopsy samples were analyzed by digital gene expression (NanoStringTM). Prespecified bioinformatics algorithm and cutoffs were applied to immune-mediated tumor regression genes (Immunosign®; Galon et al. Immunity. 2013), which included T cell-specific (effector T cell, Th1) genes, interferon pathway-related genes, chemokines, cytokines, and immune checkpoints. Expression analysis and scoring examined potential associations between TME features and response. A broader, hypothesis-generating analysis was performed using all PanCancer Immune Profiling Panel genes (770 genes) by NanoStringTM. Fisher's exact test and Wilcoxon signed rank test with multiple test correction by false discovery rate (Benjamini-Hochberg) were used.

Results: Tumor samples from all immediate pre-treatment biopsy samples that passed quality control (6 nonresponders; 21 responders) were analyzed. Pretreatment TME Immunosign21 scores were elevated in responders vs nonresponders. Responses were seen in 18/20 patients (90%) with high and 3/7 patients (43%) with low Immunosign21 scores. Immune-related genes from the Immunosign21 or Pan Cancer profile that showed higher expression at baseline in responders included CTLA4, CD3γ, CD3ϵ, CD27, and ICOSL. Genes with lower expression in responders at baseline included MHC class II genes and cancer-testis antigens. Additional correlative analyses between TME characteristics and CAR T cell activity will be presented.

Conclusions: Increased baseline expression of TME genes related to T cell activity, along with decreased expression of MHC class II and cancer testis antigens (CTAs), may be associated with a response to axi-cel. These findings should be validated in ongoing and subsequent studies.

Citation Format: John M. Rossi, Jerome Galon, Sarah Turcan, Corinne Danan, Frederick L. Locke, Sattva S. Neelapu, David B. Miklos, Caron A. Jacobson, Lazaros J. Lekakis, Yi Lin, Armin Ghobadi, William Y. Go, Adrian Bot. Characteristics of the pretreatment tumor microenvironment may influence clinical response in patients with refractory large B cell lymphoma treated with axicabtagene ciloleucel (axi-cel) in the pivotal ZUMA-1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-016.

Phase 1 Results of ZUMA-1: A Multicenter Study of KTE-C19 Anti-CD19 CAR T Cell Therapy in Refractory Aggressive Lymphoma

Outcomes for patients with refractory diffuse large B cell lymphoma (DLBCL) are poor. In the multicenter ZUMA-1 phase 1 study, we evaluated KTE-C19, an autologous CD3ζ/CD28-based chimeric antigen receptor (CAR) T cell therapy, in patients with refractory DLBCL. Patients received low-dose conditioning chemotherapy with concurrent cyclophosphamide (500 mg/m2) and fludarabine (30 mg/m2) for 3 days followed by KTE-C19 at a target dose of 2 × 106 CAR T cells/kg. The incidence of dose-limiting toxicity (DLT) was the primary endpoint. Seven patients were treated with KTE-C19 and one patient experienced a DLT of grade 4 cytokine release syndrome (CRS) and neurotoxicity. Grade ≥3 CRS and neurotoxicity were observed in 14% (n = 1/7) and 57% (n = 4/7) of patients, respectively. All other KTE-C19-related grade ≥3 events resolved within 1 month. The overall response rate was 71% (n = 5/7) and complete response (CR) rate was 57% (n = 4/7). Three patients have ongoing CR (all at 12+ months). CAR T cells demonstrated peak expansion within 2 weeks and continued to be detectable at 12+ months in patients with ongoing CR. This regimen of KTE-C19 was safe for further study in phase 2 and induced durable remissions in patients with refractory DLBCL.

Abstract 2305: Comparative evaluation of peripheral blood T cells and resultant engineered anti-CD19 CAR T cell products from relapsed/refractory non-Hodgkin's lymphoma (NHL) patients

Introduction: Administration of autologous anti-CD19 CAR T cells prepared from peripheral blood mononuclear cells (PBMC) of patients with various B cell malignancies have mediated high rates of objective response (Kochenderfer et al. Blood 2012, J Clin Onc 2014, Mackall et al, Blood 2013). We analyzed characteristics of the starting material (PBMC) and resultant CAR T cells derived from 14 patients with relapsed/refractory NHL at the NCI Surgery Branch.

Methods: After apheresis collection, the T cell-containing PBMC fraction was enriched, activated with anti-CD3 antibody and cultured in serum-free medium for 2 days. Activated T cells were transduced with a retroviral vector encoding the anti-CD19 CAR gene and further expanded with IL-2 to achieve a target dose of CAR T cells. The CAR T cells and starting PBMC population were cryopreserved and analyzed after thawing by flow cytometry. Differences in cell composition between the starting PBMC population and CAR T cells were evaluated with paired t-tests, adjusted for multiplicity.

Results: Biologically active autologous CAR T cells were successfully prepared from all 14 NHL subjects. Each product was comprised of both CD4+ and CD8+ T cells, but showed considerable inter-subject variability. The CD4/CD8 ratio in the PBMC and product CAR T cell population were correlated (Pearson correlation coefficient = 0.74, p = 0.0027). While the starting T cell population generally showed a T cell profile comprised of similar proportions of effector T cells (Teff) ($\bar{x}$ = 20%, std = 16%) and naïve T cells (Tn) ($\bar{x}$ = 20%, std = 14%), there was a shift towards a less differentiated T cells population after CAR T cell production, with a decreased Teff (paired t test p = 0.0151) and elevated Tn (p = 0.0031). The percent of juvenile cells (Tn+Tcm) was higher in the final product ($\bar{x}$ = 64%, std = 21%) than in the starting T cell population ($\bar{x}$ = 43%, std = 20%, p* = 0.0031, *stepdown Bonferonni). These products were active in vitro and in subjects with NHL. Clinical responses occurred regardless of product characteristic differences such as CD4/CD8 T cell ratio and juvenile / differentiated T cells. Additional analyses are ongoing, including evaluation of PD-1 expression,% of myeloid cells and gene expression profile.

Conclusions: CAR T cells were successfully prepared from all subjects enrolled in the study notwithstanding the diverse nature of the subject starting lymphocyte population. The CAR T cells showed a less differentiated profile, compared to the starting lymphocytes. CAR T cell production by essentially the same process described here is currently being utilized in company-sponsored multicenter trials (NCT02348216, NCT02601313).

Citation Format: Timothy Langer, Emily Lowe, Arianne Perez, Steven Rosenberg, Steven A. Feldman, Lily Lu, John M. Rossi, Edmund Chang, Marika Sherman, Marc Better, James N. Kochenderfer, Adrian Bot. Comparative evaluation of peripheral blood T cells and resultant engineered anti-CD19 CAR T cell products from relapsed/refractory non-Hodgkin's lymphoma (NHL) patients. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2305.

Abstract 2308: Manufacturing and characterization of KTE-C19 in a multicenter trial of subjects with refractory aggressive non-Hodgkin's lymphoma (NHL) (ZUMA-1)

Introduction: KTE-C19 is an autologous anti-CD19 CAR T cell product that is being studied in a phase 2 multicenter trial (ZUMA-1, NCT02348216). We developed a robust and efficient manufacturing process to support this trial, and compared the characteristics of the starting lymphocytes to resultant CAR T cells.

Methods: After apheresis and PBMC enrichment, cells were activated with anti-CD3 antibody and cultured in serum free medium. T cells were transduced with a retroviral vector encoding the CAR gene, expanded to achieve a target dose and cryopreserved. The product CAR T cells and the starting PBMCs were evaluated by flow cytometry.

Results: 7 subjects were dosed in the phase 1 portion of the trial. KTE-C19 was successfully manufactured at a dose of 2 × 106/kg (minimum 1 × 106/kg) for all subjects. All lots contained mainly CD3+ T cells (median 97%; 94-99%). While there was inter-subject variability in PBMC and CAR T cell product characteristics, the CD8/CD4 T cell ratios in PBMC and corresponding CAR product were similar (Table 1). T cells in PBMC from patients with NHL contained a majority of effector memory (36%) and effector T cells (27%), however, T cells in KTE-C19 contained a majority of central memory (37%) and effector memory (42%) CAR+ T cells. These CAR T cells were active and objective responses occurred in 5/7 patients.

Conclusions: A KTE-C19 dose was successfully produced for all subjects. The optimized manufacturing process generated clinically active CAR T cells with a less differentiated phenotype than T cells in the starting PBMC population. Less differentiated cells likely confer preferred product characteristics based on preclinical studies. This manufacturing process is robust and well suited for multicenter clinical trials. Table 1.Comparative analysis of T cells from KTE-C19 and PBMC from patients with refractory aggressive NHL.IDSampleNaïve (%)Central Memory (%)Effector Memory (%)Effector (%)CD8/CD4 ratioSubject 1KTE-C1911583014.6PBMC161246272.3Subject 2KTE-C1914473540.37PBMC26303490.27Subject 3KTE-C196345642.3PBMC4536552.9Subject 4KTE-C19111552222.0PBMC1224721.8Subject 5KTE-C1915403871.0PBMC91550261.1Subject 6KTE-C1919344252.3PBMC101359192.0Subject 7KTE-C19152645140.5PBMC121336390.5Median (Range)KTE-C1913 (6-15)37 (15-58)42 (30-56)5 (1-22)1.9 (0.4-4.6)PBMC10 (1-26)13 (2-30)36 (24-59)27 (9-72)1.9 (0.3-2.9)

Citation Format: Marc Better, Vijay Chiruvolu, James Oliver, Maryam Sorkhabi, Jeff S. Aycock, Emily Lowe, Edmund Chang, Arianne Perez, Lynn Navale, John M. Rossi, Adrian Bot. Manufacturing and characterization of KTE-C19 in a multicenter trial of subjects with refractory aggressive non-Hodgkin's lymphoma (NHL) (ZUMA-1). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2308.

Abstract CT135: Updated phase I results from ZUMA-1: a phase I-II multicenter study evaluating the safety and efficacy of KTE-C19 (anti-CD19 CAR T cells) in subjects with refractory aggressive non-Hodgkin lymphoma (NHL)

Introduction: Anti-CD19 CAR T cells with CD3 zeta and CD28 signaling domains showed durable remissions in subjects with relapsed/refractory advanced B cell malignancies at the NCI (Kochenderfer, JCO 2014). KTE-C19 utilizes the same CAR construct as investigated in the NCI study in a 6-8 day manufacturing process (Better, ASCO 2014). Updated results from the phase 1 portion of ZUMA-1 are presented here.

Methods: Subjects received KTE-C19 at a target dose of 2 × 10⁁6 anti-CD19 CAR T cells/kg after a fixed dose conditioning chemo regimen of cyclophosphamide and fludarabine. The primary objective of phase 1 was to evaluate the safety of KTE-C19 as determined by the incidence of dose-limiting toxicities (DLT). Key secondary objectives were ORR, duration of response, and biomarkers. Key inclusion criteria were ? 18 years old, ECOG 0-1, and chemo-refractory disease defined as progressive disease or stable disease as best response to last line of therapy, or disease progression ? 12 months after ASCT.

Results: As of 20 Nov 2015, 7 subjects were dosed. All subjects were evaluable for safety and 6 were evaluable for efficacy with a median follow up time of 13 weeks post KTE-C19 infusion. 1 subject experienced a DLT of grade (gr) 4 encephalopathy and gr 4 cytokine release syndrome (CRS) and died due to an intracranial hemorrhage deemed unrelated to KTE-C19 per the investigator. CRS and neurotoxicity were managed with supportive care, α-IL6R and steroids. 5 of 7 (71%) subjects responded including 4 CRs (57%). CAR T cells peaked within 2 weeks and were detectable 1-3+ months post infusion.

Conclusions: The KTE-C19 regimen evaluated was safe for further study. The predominant toxicities include CRS and neurotoxicity which are generally reversible. CRs and PRs have been observed in subjects with refractory disease. The potentially pivotal phase 2 portion of the study is ongoing (NCT02348216). SubjectSex/Age/ECOGDisease TypeTreatment HistoryGr 3 or Higher KTE-C19-Related Adverse EventsBest Response1M/59/0DLBCLRelapse ≤ 12 mo after ASCTGr 3 encephalopathy (resolved)Partial Response (PR)3M/69/1DLBCLRefractory to 2nd line chemotherapyGr 3 tremor (resolved)Complete Remission* (CR)Gr 3 delirium (resolved)Gr 3 agitation (resolved)Gr 3 restlessness (resolved)Gr 3 somnolence (resolved)4M/69/0DLBCLRefractory to 4th line chemotherapyGr 3 encephalopathy (resolved)Stable DiseaseGr 3 hypophosphataemia (resolved)5M/67/1DLBCLRelapse ≤ 12 mo after ASCTNoneComplete RemissionOngoing 3 mo+6F/34/0DLBCLRelapse ≤ 12 mo after ASCTGr 3 hypoxia (resolved)Complete RemissionOngoing 3 mo+7M/40/0DLBCLRelapse ≤ 12 mo after ASCTNoneComplete RemissionOngoing 3 mo+8F/29/1DLBCLRefractory to 1st, 2nd, 3rd line chemotherapyGr 4 CRSNEGr 4 encephalopathy

This study is supported in part by funding from The Leukemia & Lymphoma Society (LLS) Therapy Acceleration Program®

Citation Format: Armin Ghobadi, Frederick L. Locke, Sattva S. Neelapu, Tanya Siddiqi, Julio C. Chavez, Chitra M. Hosing, Nancy L. Bartlett, Lihua E. Budde, Adrian Bot, John M. Rossi, Marika Sherman, Lynn Navale, Meg Elias, Jeff Wiezorek, William Y. Go. Updated phase I results from ZUMA-1: a phase I-II multicenter study evaluating the safety and efficacy of KTE-C19 (anti-CD19 CAR T cells) in subjects with refractory aggressive non-Hodgkin lymphoma (NHL). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr CT135.

Functional EpoR pathway utilization is not detected in primary tumor cells isolated from human breast, non-small cell lung, colorectal, and ovarian tumor tissues

Several clinical trials in oncology have reported increased mortality or disease progression associated with erythropoiesis-stimulating agents. One hypothesis proposes that erythropoiesis-stimulating agents directly stimulate tumor proliferation and/or survival through cell-surface receptors. To test this hypothesis and examine if human tumors utilize the erythropoietin receptor pathway, the response of tumor cells to human recombinant erythropoietin was investigated in disaggregated tumor cells obtained from 186 patients with colorectal, breast, lung, ovarian, head and neck, and other tumors. A cocktail of well characterized tumor growth factors (EGF, HGF, and IGF-1) were analyzed in parallel as a positive control to determine whether freshly-isolated tumor cells were able to respond to growth factor activation ex vivo. Exposing tumor cells to the growth factor cocktail resulted in stimulation of survival and proliferation pathways as measured by an increase in phosphorylation of the downstream signaling proteins AKT and ERK. In contrast, no activation by human recombinant erythropoietin was observed in isolated tumor cells. Though tumor samples exhibited a broad range of cell-surface expression of EGFR, c-Met, and IGF-1R, no cell-surface erythropoietin receptor was detected in tumor cells from the 186 tumors examined (by flow cytometry or Western blot). Erythropoiesis-stimulating agents did not act directly upon isolated tumor cells to stimulate pathways known to promote proliferation or survival of human tumor cells isolated from primary and metastatic tumor tissues.

Abstract 3320: Functional RANK expression is observed in disaggregated primary human lung tumors

The receptor activator of nuclear factor-κβ (RANK) and its ligand RANKL play a key role in the regulation of bone remodeling. RANK pathway activation has also been implicated in various aspects of lung tumor biology. In mouse models of NSCLC bone metastasis, RANKL inhibition led to decreased skeletal tumor progression and increased survival. By IHC, RANK expression has been reported to occur in approximately 60-70% of NSCLC cases profiled. Expression and function have been observed using human lung cancer cell line models. However, there is a lack of understanding with respect to the role RANK signaling plays in primary human lung tumor cells. To better understand RANK biology in lung cancer a novel platform was employed to measure RANK expression and pathway response to RANKL stimulation in freshly resected human lung tumors.

RANK expression and function were investigated in viable, non-apoptotic disaggregated primary NSCLC samples by flow cytometry using previously described methodology. Cell surface RANK expression was evaluated using a monoclonal antibody (N2B10, Amgen). Evidence of receptor function was investigated by analysis of relevant intracellular signaling pathways using phospho-specific antibodies following ex vivo RANKL stimulation (2.5 pM - 5 µg/mL, 30 minutes). A cocktail of EGF, HGF and IGF1 was also employed as a positive control for functional pathway activation. Molecular profiling of somatic mutations is ongoing to further elucidate the molecular characteristics of tumors that have functional RANK signaling. Table 1 summarizes RANK expression and RANKL response profiles.

This study demonstrates that RANK is expressed and functional in a subset of primary human lung tumors. Data presented here confirms RANK expression on tumor cells of NSCLC and suggests that RANK pathway utilization is restricted to the sub-set of tumors that express detectable RANK.

Table 1SquamousAdenocarcinomaOther# Samples12217RANK Positive373NFκβ p65 Response1pAKT Response1pERK Response2p38 Responsep65 + pAKT Response1p38 + pERK Response1p65 + p38 + pAKT Response1% Responder (Total*)17%19%14%% Responder (RANK positive*)67%57%33%% Responder (EGF/ HGF/ IGF1)75%95%86%Other: large cell (1), carcinoid (1), adenosquamous (3), neuroendocrine (2)*Within Histology subtype

Citation Format: John M. Rossi, Yang Pan, William C. Dougall, Daniel Branstetter, Allison Jacob, Jude Canon, Robert D. Loberg. Functional RANK expression is observed in disaggregated primary human lung tumors. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3320. doi:10.1158/1538-7445.AM2014-3320

Apo2L/TRAIL and the death receptor 5 agonist antibody AMG 655 cooperate to promote receptor clustering and antitumor activity

Death receptor agonist therapies have exhibited limited clinical benefit to date. Investigations into why Apo2L/TRAIL and AMG 655 preclinical data were not predictive of clinical response revealed that coadministration of Apo2L/TRAIL with AMG 655 leads to increased antitumor activity in vitro and in vivo. The combination of Apo2L/TRAIL and AMG 655 results in enhanced signaling and can sensitize Apo2L/TRAIL-resistant cells. Structure determination of the Apo2L/TRAIL-DR5-AMG 655 ternary complex illustrates how higher order clustering of DR5 is achieved when both agents are combined. Enhanced agonism generated by combining Apo2L/TRAIL and AMG 655 provides insight into the limited efficacy observed in previous clinical trials and suggests testable hypotheses to reconsider death receptor agonism as a therapeutic strategy.

Distinct mesodermal signals, including BMPs from the septum transversum mesenchyme, are required in combination for hepatogenesis from the endoderm

Mesodermal signaling is critical for patterning the embryonic endoderm into different tissue domains. Classical tissue transplant experiments in the chick and recent studies in the mouse indicated that interactions with the cardiogenic mesoderm are necessary and sufficient to induce the liver in the ventral foregut endoderm. Using molecular markers and functional assays, we now show that septum transversum mesenchyme cells, a distinct mesoderm cell type, are closely apposed to the ventral endoderm and contribute to hepatic induction. Specifically, using a mouse Bmp4 null mutation and an inhibitor of BMPs, we find that BMP signaling from the septum transversum mesenchyme is necessary to induce liver genes in the endoderm and to exclude a pancreatic fate. BMPs apparently function, in part, by affecting the levels of the GATA4 transcription factor, and work in parallel to FGF signaling from the cardiac mesoderm. BMP signaling also appears critical for morphogenetic growth of the hepatic endoderm into a liver bud. Thus, the endodermal domain for the liver is specified by simultaneous signaling from distinct mesodermal sources.

Phenotypic and molecular analysis of a transgenic insertional allele of the mouse Fused locus

Spontaneous mutations at the mouse Fused (Fu) locus cause dominant skeletal and neurological defects and recessive lethal embryonic defects including neuroectodermal abnormalities and axial duplications. Here, we describe a new allele at the Fu locus caused by a transgenic insertional mutation, H epsilon 46. Embryos homozygous for the H epsilon 46 insertion die at day 9-10 post coitum and display phenotypic defects similar to those associated with Fu alleles. The H epsilon 46 locus was cloned and shown to contain a 20-kb deletion at the site of transgene insertion with no other detectable rearrangements. Genomic probes from the H epsilon 46 locus were mapped to a genetic locus closely linked to Fu on chromosome 17 and were hybridized to a YAC contig covering the FuKi critical region. Compound heterozygotes between H epsilon 46 and FuKi were inviable and displayed abnormalities at the same stage of embryogenesis as do homozygotes for either of the two mutations, demonstrating that these two recessive lethal mutations belong to the same complementation group. A genomic probe from the wild-type H epsilon 46 locus detected a transcript that is disrupted by the transgenic insertion, representing a candidate for the wild-type allele of Fused.

Genetic map of the fused locus on mouse chromosome 17

Fused (Fu) is a dominant mutation in mice resulting in the asymmetry and fusion of tail vertebrae in heterozygotes. Fu/Fu homozygotes are often viable and can exhibit a duplication of the terminal tail vertebrae resulting in bifurcated tails. There are two more severe alleles at Fu, Kinky (FuKi) and Knobbly (FuKb), which die between 9 and 10 days of gestation as homozygotes, exhibiting a duplication of the embryonic axis, leading to incomplete or complete twinning. To define the precise map position of the FuKi mutation on mouse Chromosome 17, a 983-animal (FuKi tf x Mus spretus)F1 x +tf/+tf interspecific backcross was generated and scored for FuKi, another tightly linked visible marker tufted (tf), and five linked molecular loci, D17MIT18, D17Leh54, D17Aus57, Hba-ps4, and Pim1. The order and genetic distances between the markers were determined to be centromere-D17MIT18-5.79 cM-D17Leh54-0.85 cM-D17Pri6-0.12 cM-D17Pri7-0.12 cM-Hba-ps4-1.20 cM-D17Pri8-0.48 cM-tf-2.05 cM-Pim1. The FuKi gene could not be genetically separated from three molecular markers, D17Pri6, D17Pri7, and Hba-ps4. Yeast artificial chromosome clones that contain these tightly linked markers have been isolated to form a contig that contains FuKi. Recombination breakpoints generated through the interspecies backcross were mapped onto the contig and demonstrate that recombination in this region is not random.

The consequences of expressing hsp70 in Drosophila cells at normal temperatures

In Drosophila cells, regulatory mechanisms not only act to provide rapid induction of hsp70 during heat shock but also to prevent expression at normal temperatures. To determine whether expression of hsp70 is detrimental to cells growing at normal temperatures, we used heterologous promoters to force expression of the protein in tissue culture cells and in larval salivary glands. Initially, constitutive expression of hsp70 substantially reduces the rate of cell growth. With continued expression, however, growth rates recover. At the same time, the intracellular distribution of hsp70 changes. Immediately after induction, the protein is diffusely distributed throughout the cell, but as growth resumes it coalesces into discrete points of high concentration, which we term hsp70 granules. hsp70 granules are also observed both in wild-type Drosophila tissue culture cells and in salivary glands after extended periods of recovery from heat shock. The protein in these granules appears to be irreversibly inactivated. It cannot be dispersed with a second heat shock, and cells containing these granules do not show thermotolerance. Only partial overlap between hsp70 granules and lysosomes indicates that the granules form independently of lysosomes. We conclude that expression of hsp70 is detrimental to growth at normal temperatures. We suggest that the change in hsp70 distribution, from diffuse to granular, represents a mechanism for controlling the protein's activity by sequestration.

Genomic analysis using a yeast artificial chromosome library with mouse DNA inserts

A yeast artificial chromosome library with mouse genomic DNA inserts has been constructed. The library encompasses a 2.5-fold coverage of the mouse genome, with an average insert size of 250 kilobases. The screening strategy uses the polymerase chain reaction on pooled DNAs prepared from individually stored clones. The usefulness of the library for chromosome walking was illustrated by constructing a 600-kilobase-long contig of DNA surrounding Hba-ps4, a DNA marker that is tightly linked to the fused (Fu) locus on chromosome 17.

Neurotrophic factor-like activity in Drosophila

The NGF-family of neurotrophic factors are structurally similar peptides with related functional properties. So far, this family of neurotrophic factors has only been identified in the vertebrate nervous system. We have determined that cultured Drosophila embryonic cells produce and secrete into medium, an activity which stimulates neurite outgrowth of embryonic chick sensory ganglia. This Drosophila activity can be blocked by antibodies to mouse NGF, indicating an immunological relationship between the Drosophila factor, mouse NGF and possibly other vertebrate neurotrophic factors. Addition of mouse NGF to Drosophila embryonic cells in culture results in increased cell number and enrichment of the neuronal phenotype, indicating that Drosophila cells have the ability to respond to the vertebrate factor. In addition, poly(A)+RNA extracted from Drosophila contains a single 1.4 Kb band which cross-hybridizes with a mouse NGF cRNA probe. These results indicate that vertebrate neurotrophic factor-like functions may operate in a genetically defined invertebrate species.