Combination checkpoint therapy with anti-PD-1 and anti-BTLA results in a synergistic therapeutic effect against murine glioblastoma

• Published in: Oncoimmunology Vol. 10; no. 1; p. 1956142
• Main Authors: Choi, John, Medikonda, Ravi, Saleh, Laura, Kim, Timothy, Pant, Ayush, Srivastava, Siddhartha, Kim, Young-Hoon, Jackson, Christina, Tong, Luqing, Routkevitch, Denis, Jackson, Christopher, Mathios, Dimitrios, Zhao, Tianna, Cho, Hyerim, Brem, Henry, Lim, Michael
• Format: Journal Article
• Language: English
• Published: Taylor & Francis 01.01.2021; Taylor & Francis Group
• Subjects: anti-BTLA; anti-PD-1; B and T lymphocyte attenuator; glioblastoma; glioblastoma immunotherapy; immune checkpoint inhibitor therapy; Original Research
• ISSN: 2162-402X; 2162-4011; 2162-402X
• DOI: 10.1080/2162402X.2021.1956142

Clinical trials involving anti-programmed cell death protein-1 (anti-PD-1) failed to demonstrate improved overall survival in glioblastoma (GBM) patients. This may be due to the expression of alternative checkpoints such as B- and T- lymphocyte attenuator (BTLA) on several immune cell types including regulatory T cells. Murine GBM models indicate that there is significant upregulation of BTLA in the tumor microenvironment (TME) with associated T cell exhaustion. We investigate the use of antibodies against BTLA and PD-1 on reversing immunosuppression and increasing long-term survival in a murine GBM model. C57BL/6 J mice were implanted with the murine glioma cell line GL261 and randomized into 4 arms: (i) control, (ii) anti-PD-1, (iii) anti-BTLA, and (iv) anti-PD-1 + anti-BTLA. Kaplan-Meier curves were generated for all arms. Flow cytometric analysis of blood and brains were done on days 11 and 16 post-tumor implantation. Tumor-bearing mice treated with a combination of anti-PD-1 and anti-BTLA therapy experienced improved overall long-term survival (60%) compared to anti-PD-1 (20%) or anti-BTLA (0%) alone (P = .003). Compared to monotherapy with anti-PD-1, mice treated with combination therapy also demonstrated increased expression of CD4+ IFN-γ (P < .0001) and CD8+ IFN-γ (P = .0365), as well as decreased levels of CD4+ FoxP3+ regulatory T cells on day 16 in the brain (P = .0136). This is the first preclinical investigation into the effects of combination checkpoint blockade with anti-PD-1 and anti-BTLA treatment in GBM. We also show a direct effect on activated immune cell populations such as CD4+ and CD8 + T cells and immunosuppressive regulatory T cells through this combination therapy.