CSPG4-specific CAR.CIK lymphocytes as a novel therapy for the treatment of multiple soft tissue sarcoma histotypes

CSPG4-specific CAR.CIK lymphocytes as a novel therapy for the treatment of multiple soft tissue sarcoma histotypes:

Purpose: No effective therapy is available for unresectable soft tissue sarcomas (STS). This unmet clinical need has prompted us to test whether chondroitin sulfate proteoglycan 4 (CSPG4)-specific CAR-redirected cytokine-induced killer lymphocytes (CAR.CIK) are effective in eliminating tumor cells derived from multiple STS histotypes in vitro and in immunodeficient mice. Experimental Design: The experimental platform included patient-derived CAR.CIK and cell lines established from multiple STS histotypes. CAR.CIK were transduced with a retroviral vector encoding 2^nd-generation CSPG4-specific CAR (CSPG4-CAR) with 4-1BB co-stimulation. The functional activity of CSPG4-CAR.CIK was explored in vitro, in 2D and 3D STS cultures, and in three in vivo STS xenograft models. Results: CSPG4-CAR.CIK were efficiently generated from STS patients. CSPG4 was highly expressed in multiple STS histotypes by in silico analysis and on all the 16 STS cell lines tested by flow cytometry. CSPG4-CAR.CIK displayed superior in vitro cytolytic activity against multiple STS histotypes as compared to paired unmodified control CIK. CSPG4-CAR.CIK also showed strong anti-tumor activity against STS spheroids; this effect was associated with tumor recruitment, infiltration, and matrix penetration. CSPG4-CAR.CIK significantly delayed or reversed tumor growth in vivo in three STS xenograft models (Leiomyosarcoma, UPS and Fibrosarcoma). Tumor growth inhibition persisted for up to 2 weeks following the last administration of CSPG4-CAR.CIK. Conclusions: This study has shown that CSPG4-specific CAR-redirected CIK effectively target multiple STS histotypes in vitro and in immunodeficient mice. These results provide a strong rationale to translate the novel strategy we have developed in to a clinical setting.