Phase I study of autologous transgenic T cells expressing high affinity mesothelin-specific T-cell receptor (TCR; FH-TCR TMSLN) in patients with metastatic pancreatic ductal adenocarcinoma (mPDA)

TPS779

Background: PDA has a low tumor mutational burden and an immunosuppressive microenvironment. Targeting overexpressed self-antigens with adoptive, genetically engineered, high affinity T cells may overcome immunosuppression (Stromnes I, Immunol Rev 2014). We previously engineered murine CD8+ T cells to express a high affinity MSLN-specific TCR in the KrasLSL-G12D/+; Trp53LSL-R172H/+; p48Cre/+ ( KPC) mouse model, with highest efficacy observed following serial infusions (Stromnes I, Cancer Cell 2015). We developed an autologous TCR-T cell therapy targeting MSLN, which is overexpressed by 80% of PDAs. In this first-in-human phase I trial, we seek to determine the safety, preliminary efficacy, as well as the persistence, activation, localization, and functional capacity of FH-TCR TMSLN in chemotherapy refractory, MSLN+ mPDA. Methods: Eligible pts have ECOG PS 0-1, ≥ 1 prior therapy for mPDA, life expectancy ≥ 12 wks, able/willing to undergo biopsies (at baseline, and after 3 and 6 wks of treatment), MSLN 2+ expression in ≥ 30% tumor cells by IHC, HLA-A*02:01, no HLA-B*13:02. Patients undergo leukapheresis, and approximately 3-4 weeks later, receive the first TCR-TMSLN cell infusion. Three TCR-TMSLN cell infusions given q21 days (d) are planned to be administered to each patient. Patients are enrolled in 4 cohorts by dose level (cohort 1: 1 x 109; cohort 2: 3.3 x 109; cohorts 3 and 4: 10 x 109 T cells), with a 3+3 design. Dose limiting toxicities (DLTs) are assessed during 21d after each TCR-TMSLN cells infusion. Lymphodepleting chemotherapy with fludarabine/cyclophosphamide is administered prior to the third TCR-TMSLN infusion (cohorts 1-3) or prior to the first TCR-TMSLN infusion (cohort 4). Primary endpoint is safety and DLTs. Secondary endpoints are ORR, PFS, OS. Exploratory endpoints are translational tumor and blood TCR-TMSLN cells biomarkers. Safety is assessed by CTCAE v5.0, with a goal of grade ≥ 3 TCR-TMSLN cells unexpected toxicity rate <35%; stopping rate if toxicity is ≥20% is 0.06. Response is assessed by RECIST 1.1. Enrollment of 15 patients allows >80% power to observe a statistically significant (one-sided alpha level 0.05), meaningful efficacy signal of ORR 20%. Secondary and exploratory endpoints will be descriptive and hypothesis generating. The study was activated in December 2021 and is open to accrual; 4 patients have been enrolled as of 24 Sept 2022. Clinical trial information: NCT04809766 .

Attamage-A1: Phase I/II study of autologous CD8+ and CD4+ transgenic t cells expressing high affinity MAGE-A1-specific T-cell receptor (TCR) combined with anti-PD(L)1 in patients with metastatic MAGE-A1 expressing cancer

TPS592

Background: Adoptive cellular therapies can lead to durable responses in treatment refractory leukemias and lymphomas; however, these approaches are still in early stage development for metastatic solid tumors. FH-MagIC TCR-T is an autologous CD8+ and CD4+ T cell product transduced with a transgenic T cell receptor (TCR) targeting MAGE-A1. MAGE-A proteins are classified within the “testis restricted” cancer testis antigens and are broadly expressed in a wide range of malignancies, including urothelial carcinomas, triple negative breast cancers (TNBCs) and non-small cell lung cancers (NSCLCs). Importantly, MAGE-A1 is undetectable in most normal tissues exclusive of the immune privileged testes, thereby making MAGE-A1 an ideal target for T cell immunotherapy approaches. Of note, FH-MagIC TCR-T is specific to the Class I HLA A*02:01-restricted MAGE-A1 epitope. Based on preclinical studies testing FH-MagIC-T in MAGE-A1 expressing tumor models, we have launched a Phase I/II study evaluating this autologous transgenic TCR therapy. Methods: This is a Phase I/II study testing FH-MagIC TCR-T cells in patients with metastatic urothelial carcinoma, TNBC or NSCLC. Eligible patients must have HLA type HLA-A*02:01 and demonstrate expression of MAGE-A1 on archival tumor tissue (≥1+ by immunohistochemistry). Patients must have been offered or received: i) anti-PD(L)1 therapy; ii) enfortumab vedotin (urothelial carcinoma patients); and iii) FDA-approved targeted therapies (e.g. NSCLC patients with actionable mutations in EGFR, ROS1, etc.). For each dose level (DL) in the Phase 1 portion, 1 patient will be treated without lymphodepletion (LD). If no dose limiting toxicities (DLT) are observed, the next 3 patients will receive LD with cyclophosphamide 300mg/m2 and fludarabine 30mg/m2 IV days -4 to -2 before T cell infusion. The first 4 patients will be treated at DL1: 1 x 109 cells. If no DLTs are observed, the next 4 patients will be treated at DL2: 5 x 109 cells. Otherwise, if a DLT is observed at DL1, the next 4 patients will be treated at DL-1: 5 x 108 cells. The Phase 2 portion of the trial will test FH-MagIC-TCR T cell product at the RP2D with the addition of standard of care anti-PD(L)1 therapy. Primary objectives are to assess safety (Phase 1) and radiographic response rate (Phase 2) per RECIST v1.1. Secondary objectives will evaluate progression free survival, overall survival, persistence of transgenic T cells in peripheral blood and migration into tumor tissue. For the Phase 2 portion, we assume a 5% null response rate (H0). If the true response rate with TCR-transduced cells is 25% (H1), 15 patients will yield 84% power at a one-sided alpha =.05. Clinical trial information: NCT04639245.