CRISPR-engineered T cells in patients with refractory cancer

CRISPR-Cas9 gene editing provides a powerful tool to enhance the natural ability of human T cells to fight cancer. We report a first-in-human phase 1 clinical trial to test the safety and feasibility of multiplex CRISPR-Cas9 editing to engineer T cells in three patients with refractory cancer. Two genes encoding the endogenous T cell receptor (TCR) chains, TCRα (TRAC) and TCRβ (TRBC), were deleted in T cells to reduce TCR mispairing and to enhance the expression of a synthetic, cancer-specific TCR transgene (NY-ESO-1). Removal of a third gene encoding programmed cell death protein 1 (PD-1; PDCD1), was performed to improve antitumor immunity. Adoptive transfer of engineered T cells into patients resulted in durable engraftment with edits at all three genomic loci. Although chromosomal translocations were detected, the frequency decreased over time. Modified T cells persisted for up to 9 months, suggesting that immunogenicity is minimal under these conditions and demonstrating the feasibility of CRISPR gene editing for cancer immunotherapy.

Phase I Trial of Autologous RNA-electroporated cMET-directed CAR T Cells Administered Intravenously in Patients with Melanoma and Breast Carcinoma

Purpose

Treatments are limited for metastatic melanoma and metastatic triple-negative breast cancer (mTNBC). This pilot phase I trial (NCT03060356) examined the safety and feasibility of intravenous RNA-electroporated chimeric antigen receptor (CAR) T cells targeting the cell-surface antigen cMET.

Experimental Design

Metastatic melanoma or mTNBC subjects had at least 30% tumor expression of cMET, measurable disease and progression on prior therapy. Patients received up to six infusions (1 × 10e8 T cells/dose) of CAR T cells without lymphodepleting chemotherapy. Forty-eight percent of prescreened subjects met the cMET expression threshold. Seven (3 metastatic melanoma, 4 mTNBC) were treated.

Results

Mean age was 50 years (35-64); median Eastern Cooperative Oncology Group 0 (0-1); median prior lines of chemotherapy/immunotherapy were 4/0 for TNBC and 1/3 for melanoma subjects. Six patients experienced grade 1 or 2 toxicity. Toxicities in at least 1 patient included anemia, fatigue, and malaise. One subject had grade 1 cytokine release syndrome. No grade 3 or higher toxicity, neurotoxicity, or treatment discontinuation occurred. Best response was stable disease in 4 and disease progression in 3 subjects. mRNA signals corresponding to CAR T cells were detected by RT-PCR in all patients' blood including in 3 subjects on day +1 (no infusion administered on this day). Five subjects underwent postinfusion biopsy with no CAR T-cell signals seen in tumor. Three subjects had paired tumor tissue; IHC showed increases in CD8 and CD3 and decreases in pS6 and Ki67.

Conclusions

Intravenous administration of RNA-electroporated cMET-directed CAR T cells is safe and feasible.

Significance

Data evaluating CAR T therapy in patients with solid tumors are limited. This pilot clinical trial demonstrates that intravenous cMET-directed CAR T-cell therapy is safe and feasible in patients with metastatic melanoma and metastatic breast cancer, supporting the continued evaluation of cellular therapy for patients with these malignancies.

Phase I trial of autologous cMET-directed CAR-t cells administered intravenously in patients with melanoma & breast carcinoma

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Background: Advanced relapsed/refractory melanoma and metastatic triple-negative breast cancer are lethal diseases for which effective therapies are limited. We conducted a pilot phase I clinical trial (NCT03060356) to establish the safety and feasibility of intravenous autologous chimeric antigen receptor (CAR) T cell immunotherapy targeting cMET, a cell-surface antigen that is highly expressed in these cancers. Methods: Subjects had metastatic or unresectable melanoma (Mel) or triple-negative breast cancer (BC) with ≥30% expression of cMET on archival tissue or screening biopsy. Eligible subjects had measurable disease and progression on at least 1 prior therapy. Patients (pts) received up to 6 doses (1x108 total T-cells per dose) of RNA electroporated anti-cMET CAR T cells over a 2-week period without antecedent lymphodepleting chemotherapy. Subjects underwent pre- and post-infusion biopsies. The primary objective was to determine feasibility and safety of treatment. Results: 77 subjects (39 mel, 38 BC) were prescreened for tumor cMET expression and 37 (17 mel, 20 BC) met the eligibility threshold. Seven pts (4 BC, 3 Mel) received cMET-directed CAR T infusions on study. Mean age was 50 years (35-64); median (M) ECOG 0 (0-1); M prior lines of chemotherapy/immunotherapy were 4/0 for BC pts and 1/3 for Mel pts. 6 of 7 pts received all planned CAR T cell infusions, and 1 received 5 infusions. 5 pts experienced grade (G) 1 or G 2 toxicity that was possibly or definitely related to study. Toxicities occurring in ≥1 pt included: anemia (n = 3), fatigue (n = 2), and malaise (n = 2). No G ≥3 toxicities or cytokine release syndrome were observed. No pts discontinued therapy due to toxicity. Best response was stable disease in 4 pts (2 BC, 2 Mel) and PD in 3 pts (2 BC, 1 Mel). Messenger RNA signals corresponding to CAR T cells were detected by RT-PCR in the peripheral blood of all pts during the infusion period and in 2 pts after the infusion period. 6 pts underwent baseline biopsy and 4 pts underwent post-infusion biopsy. Immunohistochemical stains of CD3, CD4, CD8, CD163, L26, PD1, PDL1, Foxp3, Ki67, Granzyme B and Phospho-S6 were performed on pre- and post-treatment tissue biopsies and are being evaluated. Conclusions: Intravenous administration of RNA-electroporated cMET-directed CAR T cells was safe and feasible. Future directions include examination of this target using a lentiviral construct in combination with lymphodepleting chemotherapy. Clinical trial information: NCT03060356.

431 First-in-human phase I clinical trial evaluating intraperitoneal administration of MOv19-BBz CAR T cells in patients with alpha folate receptor-expressing recurrent high grade serous ovarian cancer

Background

Most women with epithelial ovarian cancer develop uniformly incurable disease recurrence. Chimeric antigen receptor (CAR) T cells pair the MHC-independent tumor-recognition capabilities of monoclonal antibodies with the cytotoxicity of effector T cells. The success of CAR T cell therapy in solid tumors has been hindered by (1) difficulty identifying highly expressed, tumor-specific, cell surface target antigens; (2) limited trafficking and infiltration; and (3) suboptimal cytotoxic activity. Alpha folate receptor (FRα) is a transmembrane protein involved in cellular folate transport; expression has been reported in 80% of ovarian cancer, with limited physiologic expression on epithelial cells including bronchial, renal, and intestinal tissue. We hypothesize that intraperitoneal administration of alpha folate receptor (FRα) directed CAR T cells with dual 4-1BB and TCRzeta signaling domains will circumvent the above challenges and be safe, feasible, and elicit anti-tumor responses.

Methods

We initiated a first-in-human phase I clinical trial to evaluate the feasibility, safety and preliminary efficacy of intraperitoneal administration of FRα directed CAR T cells with and without antecedent lymphodepleting chemotherapy (LDC) in women with recurrent high grade serous ovarian cancer. The lentivirally-transduced CAR is composed of a MOv19 anti-FRα-specific single chain variable fragment fused to 4-1BB and TCRzeta signaling domains. Eligible patients have persistent or recurrent high grade serous epithelial ovarian, fallopian tube, or primary peritoneal carcinoma that is not platinum refractory and expresses ≥2+ FRα staining in ≥70% of tumor cells. Subjects must have an ECOG performance status 0–1, measurable disease, adequate hematologic and organ function, and must have progressed on at least two prior chemotherapy regimens for advanced disease. Patients undergo biopsy pre-infusion and Day +14 after infusion. After same-day placement of an intraperitoneal catheter by Interventional Radiology, CAR T cells are administered via a single infusion on three dose cohorts: Cohort 1 (starting cohort), 1–3x107/m2 cells without LDC; Cohort 2, 1–3x107/m2 CAR T cells after LDC; Cohort 3, 1–3x108/m2 cells after LDC. Catheter is removed after infusion. A 3+3 dose escalation design to determine maximum tolerated dose (MTD) yields approximately 9 to 18 subjects. The primary objective is safety and feasibility, and secondary objectives are anti-tumor response (endpoints: overall response rate based on RECIST v 1.1 and irRECIST when feasible, progression-free survival and overall survival). Correlative endpoints include CAR T cell engraftment and persistence in peripheral blood and body fluids examined via quantitative PCR of CAR T DNA, and bioactivity of CAR T cells. Enrollment is ongoing.

Trial Registration

This trial is registered at ClinicalTrials.gov (NCT03585764).

Ethics Approval

This study was approved by the Institutional Review Board at the University of Pennsylvania (IRB 830111). All subjects provided written informed consent prior to any study-related procedures.