Abstract 4707: Genetically engineered NY-ESO-1-specific T cells in HLA-A2+ patients with synovial sarcoma

NY-ESO-1 is expressed in ∼70% of synovial sarcomas and not expressed in vital tissues. We report interim results of NCT01343043 evaluating safety and activity of autologous T cells engineered to express an HLA-A2+ restricted, affinity-enhanced T cell receptor (TCR) targeting NY-ESO-1. HLA-A2+ patients with unresectable, metastatic, or recurrent synovial sarcoma were eligible if tumors expressed NY-ESO-1 by IHC. Lymphocytes were activated using anti-CD3/28 microbeads, genetically modified with a lentivector, then cryopreserved. Subjects received fludarabine 30mg/m2/d (D-6 to -2) and cyclophosphamide 1800mg/m2/d (D-3,-2), and infusion of engineered T cells. Systemic IL-2 was not administered. Nine subjects have received NY-ESO-1 cell infusions. Median transduced T cell dose was 3.4 × 109 cells (range 0.4-14.4), 60×106 cells/kg (range 5.7-165.5), and median transduction efficiency was 45.8%. Toxicity likely attributable to the T cells included fever, and grade 1-2 cytokine release syndrome. No autoimmune toxicity has been observed. Circulating engineered NY-ESO-1 cells were detected in all patients, peaking 3-21 days post-infusion. Persistence has been evaluated beyond 3 months in 4 subjects, all of whom had detectable NY-ESO-1 cells at 4 mos, 6 mos+, 12 mos+ and 12 mos+. We identified persisting NY-ESO-1 T cells using dextamer and/or anti-vβ13.1 mAbs, and observed that a high fraction of CD4+ and CD8+ NY-ESO-1 TCR expressing T cells were CD45RA+CCR7+CD95+, consistent with a stem cell memory phenotype. Persisting cells also demonstrate a polyfunctional (IFN-γ and TNF-α) and cytotoxic (CD107a and granzyme B) signature without overexpression of exhaustion markers (PD-1, LAG-3, and TIM-3). Of 8 patients whose follow-up is sufficient to assess response, 4 experienced objective responses (1CR x 9 mos, 1PR x 9 mos, 2PR x 6 mos). Tumor shrinkage could not be attributed to chemotherapy alone as progressive decreases in tumor size were observed over several months following completion of the lymphodepleting regimen. All PR patients (2 upon signs of progression and 1 still responding to therapy) ultimately underwent resection for residual disease and two remain without evidence of disease. Adoptive immunotherapy with NY-ESO-1 engineered T cells shows promising results in synovial sarcoma with acceptable toxicity. High dose IL-2 is not required for therapeutic benefit with this regimen. Citation Format: Melinda S. Merchant, Sandra P. D9Angelo, Hua Zhang, Donna Bernstein, Gwen Binder-Scholl, Tom Holdich, Luca Melchiori, Dan Williams, Marylene Fortin, Yoav Peretz, Jason Howe, Michael Mehler, Bruce A. Hug, Matthew Wright, Stephen Grupp, Paul A. Meyers, William Tap, Bent Jakobsen, Crystal L. Mackall. Genetically engineered NY-ESO-1-specific T cells in HLA-A2+ patients with synovial sarcoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4707. doi:10.1158/1538-7445.AM2015-4707