Immune Checkpoint Blockade via PD-L1 Potentiates More CD28-Based than 4-1BB-Based Anti-Carbonic Anhydrase IX Chimeric...

Area of Science:

• Immunotherapy
• Oncology
• Cellular Therapy

Background:

• Clear cell renal cell carcinoma (ccRCC) is a significant cause of cancer-related mortality.
• Carbonic anhydrase IX (CAIX) is a tumor-associated antigen overexpressed in hypoxic ccRCC.
• Immune checkpoint blockade (ICB) has shown efficacy in advanced ccRCC, but novel therapeutic strategies are needed.

Purpose of the Study:

• To evaluate the efficacy of CD28-based versus 4-1BB-based anti-CAIX chimeric antigen receptor (CAR) T cells engineered to release anti-programmed cell death ligand-1 (PD-L1) antibodies for ccRCC treatment.
• To assess the anti-tumor activity and safety profile of these CAR T cells in vitro and in an in vivo mouse model.
• To investigate the role of T cell exhaustion in CAR T cell efficacy.

Main Methods:

• Development and in vitro testing of CD8α/4-1BB and CD28-based anti-CAIX CAR T cells engineered to secrete anti-PD-L1 IgG4.
• In vivo efficacy studies in an orthotopic NSG mice model of human ccRCC using a dose of approximately 10^7 CAR PBMCs/kg.
• Assessment of tumor volume, weight, metastasis, and T cell exhaustion markers (CD4 and CD8 T cells).

Main Results:

• Anti-CAIX CD28 CAR T cells releasing anti-PD-L1 significantly reduced tumor volume and weight in vivo, while preventing metastasis.
• CD28-based CAR T cells demonstrated superior anti-tumoral activity compared to 4-1BB-based CAR T cells under PD-L1 blockade.
• T cell exhaustion in both CD4 and CD8 peripheral T cells was identified as critical for CAR T cell efficiency.
• No hepatotoxicity or nephrotoxicity was observed at the tested dose of 10^7 CAR PBMCs/kg.

Conclusions:

• CD28-based anti-CAIX CAR T cells secreting anti-PD-L1 antibodies represent a promising therapeutic strategy for ccRCC.
• The combination of CAR T cell therapy and PD-L1 blockade offers enhanced anti-tumor efficacy.
• The safety profile and efficacy observed support the translation of these CAR T cells into clinical trials for refractory ccRCC and other hypoxic tumors.