Immunotherapy with T cells expressing the chimeric antigen receptor (CAR) specific for the CD19 antigen (CD19.CAR-Ts) is a very effective treatment in B cell lymphoid malignancies. However, B cell aplasia and cytokine release syndrome (CRS) secondary to the infusion of CD19.CAR-Ts remain significant drawbacks. The inclusion of safety switches into the vector encoding the CAR is seen as the safest method to terminate the effects of CD19.CAR-Ts in case of severe toxicities or after achieving long-term sustained remissions. By contrast, the complete elimination of CD19.CAR-Ts when CRS occurs may jeopardize clinical responses as CRS and antitumor activity seem to concur. We have demonstrated, in a humanized mouse model, that the inducible caspase-9 (iC9) safety switch can eliminate CD19.CAR-Ts in a dose-dependent manner, allowing either a selective containment of CD19.CAR-T expansion in case of CRS or complete deletion on demand granting normal B cell reconstitution.
Adoptive immunotherapy for HL associated with EBV infection has had considerable success, inducing >50% complete and sustained remission rates in patients (pts) with relapsed/resistant disease. However, only 40% of HL pts express EBV-associated antigens. By contrast, almost all HL and some NHL (e.g., anaplastic large cell lymphoma – ALCL) express the CD30 antigen, and monoclonal antibodies (mAb) targeting CD30 produce objective antitumor responses. mAb, however, have restricted bio-distribution, and their effects may be limited in duration. We therefore expressed the antigen binding domain of a CD30 mAb as part of a chimeric antigen receptor (CAR) on T cells, coupled to the CD28 and ζ chain endodomains, in an effort to ensure prolonged persistence, active penetration of tumors, and activation of multiple lytic components of the immune system. We report here a preliminary analysis of our phase 1 dose escalation study of activated autologous CD30.CAR-T cells (CD30.CARTs) infused in pts with relapsed/refractory EBV-negative CD30+HL or NHL. We manufactured CD30.CARTs for 18 pts using retroviral transduction. Starting from a median of 2.4×107 PBMCs (range 3.6×106 to 4.9×107), we obtained 9.0×108 CD30.CARTs (range 2.8×108 to 2.9×109) in 15±3 days of culture, with a transduction efficiency of 89±1%. The cell products comprised >99% T cells and phenotypic analysis showed 58±29% CD8+ T cells, with a majority being effector T cells (94±7% CD45RO+ cells). 51Cr-release cytotoxicity assays confirmed that patients' CD30.CARTs lysed a CD30+ tumor line, HDLM-2 (60±13% killing at a 20:1 effector:target ratio), with negligible effects on CD30− target cells (<5% killing). Nine pts (7 with HL and 2 ALCL) have received CD30.CARTs: 8 had relapsed or progressed after treatment with the CD30 mAb brentuximab; 2 pts were treated on dose level (DL) 1 (2×107 CD30.CAR+ T cells/m2), 2 on DL2 (1×108), and 5 on DL3 (2×108). No pt received conditioning before CART infusion. No attributable adverse events were seen; in particular, no pt had evidence of cytokine release syndrome. As CD30 can be transiently expressed by activated T cells (e.g., during infection with viruses), we monitored antiviral immunity in CART recipients. The frequency of T cells responding to CMV, adenovirus, influenza virus and EBV remained unchanged by treatment. The molecular signal from CARTs, assessed by Q-PCR in peripheral blood, was dose dependent and peaked at 1 wk following infusion (mean of 7020 copies/mg DNA for DL3 vs. 60 copies/mg for DL1), but decreased to near background by 4 wk. At 6 wk after treatment, 1 pt had a CR, 1 pt had a very good PR, and 4 pts had stable disease persisting for 1½ to 8 months, while 3 pts had disease progression. Having found that DL3 is safe and associated with significant in vivo expansion and response, we will now explore the use of these cells after conditioning chemotherapy or autologous stem cell transplantation.
Targeting CD30 with monoclonal antibodies in Hodgkin lymphoma (HL) and anaplastic large cell lymphoma (ALCL) has had profound clinical success. However, adverse events, mainly mediated by the toxin component of the conjugated antibodies, cause treatment discontinuation in many patients. Targeting CD30 with T cells expressing a CD30-specific chimeric antigen receptor (CAR) may reduce the side effects and augment antitumor activity.We conducted a phase I dose escalation study in which 9 patients with relapsed/refractory HL or ALCL were infused with autologous T cells that were gene-modified with a retroviral vector to express the CD30-specific CAR (CD30.CAR-Ts) encoding the CD28 costimulatory endodomain. Three dose levels, from 0.2 × 108 to 2 × 108 CD30.CAR-Ts/m2, were infused without a conditioning regimen. All other therapy for malignancy was discontinued at least 4 weeks before CD30.CAR-T infusion. Seven patients had previously experienced disease progression while being treated with brentuximab.No toxicities attributable to CD30.CAR-Ts were observed. Of 7 patients with relapsed HL, 1 entered complete response (CR) lasting more than 2.5 years after the second infusion of CD30.CAR-Ts, 1 remained in continued CR for almost 2 years, and 3 had transient stable disease. Of 2 patients with ALCL, 1 had a CR that persisted 9 months after the fourth infusion of CD30.CAR-Ts. CD30.CAR-T expansion in peripheral blood peaked 1 week after infusion, and CD30.CAR-Ts remained detectable for over 6 weeks. Although CD30 may also be expressed by normal activated T cells, no patients developed impaired virus-specific immunity.CD30.CAR-Ts are safe and can lead to clinical responses in patients with HL and ALCL, indicating that further assessment of this therapy is warranted.ClinicalTrials.gov NCT01316146.National Cancer Institute (3P50CA126752, R01CA131027 and P30CA125123), National Heart, Lung, and Blood Institute (R01HL114564), and Leukemia and Lymphoma Society (LLSTR 6227-08).
283 Background: PSCA, a cell surface protein, is upregulated in many solid tumors and correlates with disease stage. BPX601 is an autologous, T-cell product engineered to contain a PSCA-CD3ζ CAR plus the small molecule rimiducid (Rim)-inducible MyD88/CD40 costimulatory domain. BPX601 is optimized for antigen-directed and independent T cell activation, proliferation and persistence, potentially enhancing efficacy in solid tumors versus traditional CARs. This first-in-human study assesses the safety, biological and clinical activity of BPX601 plus Rim in select PSCA-positive cancers. Methods: NCT02744287 is a two-part, open-label trial. Part 1 is an ongoing 3+3 cell dose escalation to identify the recommended BPX601 cell dose (Day 0) given in combination with a fixed, single Rim dose (0.4 mg/kg; Day 7). Eligibility criteria include previously treated metastatic pancreatic cancer (mPDAC) with measurable disease & positive PSCA expression. Results: Patients received only cyclophosphamide (CTX) for lymphodepletion (LD) within three days before BPX601 infusion. Nine adults have been treated across three cell dose levels (cells/kg): 1.25x10 6 (cells only), 1.25x10 6 +Rim, 2.5x10 6 +Rim. All had mPDAC with ≥ two prior therapies. Common AEs were fatigue and nausea. No DLTs, related SAEs, neurotoxicity or CRS events were reported. Rapid cell engraftment by Day 4 was observed in all patients. No evidence of LD with CTX was seen. Of six patients that received Rim: two had cell expansion 10- to 20-fold within seven days; two had cell persistence > three weeks; all had elevated serum cytokines (IP-10, TNFα) correlated with cell expansion. Best response after ≥ one scan was 4 SD ≥ eight weeks with two minor responses (not confirmed; one patient had matched CA19-9 decrease) and 2 PD. Disease control without new therapy was 16 and > 11 weeks (ongoing) in one and two patients, respectively. Conclusions: BPX601 with single-dose Rim was well-tolerated and resulted in enhanced T cell expansion and prolonged persistence in some patients despite lack of LD. Evidence of clinical benefit in this heavily pretreated mPDAC population was seen. Part 2 is planned to open soon and will include CTX/fludarabine LD to maximize engraftment as well as gastric and prostate cancers. Clinical trial information: NCT02744287.
734 Background: PSCA is a cell surface protein overexpressed in approximately 60% of pancreatic cancers. BPX-601 is an autologous GOCAR-T cell therapy engineered to express a PSCA-CD3ζ CAR and the MyD88/CD40 (iMC) costimulatory domain activated by rimiducid (Rim), designed to boost CAR-T performance in solid tumors. The safety and activity of BPX-601 activated with Rim in PSCA + metastatic pancreatic cancer is being assessed in a Phase 1/2 clinical trial, BP-012 (NCT02744287). Methods: Phase 1 of BP-012 is a 3+3 dose escalation of BPX-601 (1.25-5 x10 6 /kg) administered on Day 0 with a single, fixed-dose of Rim (0.4 mg/kg) on Day 7 in subjects with previously treated PSCA + metastatic pancreatic cancer. All 5 subjects in cohort 5B received Flu/Cy lymphodepletion followed by BPX-601 (5 x10 6 /kg) and Rim. BPX-601 kinetics, PBMC phenotype, and serum cytokines were assayed by qPCR, flow cytometry, and cytokine multiplex, respectively. Baseline and on-treatment biopsies were evaluated by RNAscope in situ hybridization. Results: BPX-601 cells expanded in all subjects and persisted up to 9 months (median 42 days). Transient reduction in BPX-601 vector copy number and total T cell count concurrent with Rim infusion, supports margination of activated BPX-601 cells. Increased serum cytokines, such as IFN-γ and GM-CSF, were observed following BPX-601 infusion with further elevation after Rim activation. All subjects with evaluable on-treatment biopsies had infiltration of BPX-601 cells (n = 3) proximal to tumor cells 7-15 days after Rim, but not in an end of treatment biopsy > 200 days after Rim (n = 1). Stratification by best response (RECIST 1.1) revealed stable disease in 3 subjects and progressive disease in 2 subjects was potentially associated with distinct cytokine signatures. Conclusions: BPX-601 GOCAR-T cells expand and persist in patients with PSCA + metastatic pancreatic cancer and infiltrate metastatic lesions. A peripheral cytokine signature was observed following BPX-601 infusion. Select cytokines were enhanced after GOCAR-T cell activation and may correlate with clinical response. A cohort of subjects exploring serial administration of Rim is open for enrollment. Clinical trial information: NCT02744287.
