CARPE DIEM CAR-T cells anti-hPSMA endowed with dominant negative truncated high-affinity PD-1 molecule: a new immunostrategy

Prostate cancer is one of the leading causes of malignancy-related death among males, and relapse or refractory tumors are still unmet clinical needs for current treatment options. This research project aims to generate a strategy to improve the current Adoptive Cell Therapy (ACT) research against prostate cancer, by empowering anti-human Prostate Specific Membrane Antigen (hPSMA) Chimeric Antigen Receptor (CAR)-engineered T cells with a novel genetic weapon, able to interfere with the PD-1/PD-L1 immune checkpoint pathway, endorsed by the membrane expression of a truncated high-affinity PD-1 molecule (haPD-1). The CAR-haPD-1 cassette expression was already detectable 72 hours post-transduction, and the phenotypic profile was comprehensively analyzed by flow cytometry. Co-incubation experiments aimed at functionally examining the cytotoxicity as well as cytokine release ability specifically in the presence of the target antigen and correlation to the levels of PD-L1-induced inhibition caused by tumor cells. The therapeutic effect was then further evaluated in prostate tumor mouse models. The T cell population expressing anti-hPSMA CAR/haPD-1 displayed effector function, proficiently identifying and managing hPSMA-expressing tumor cells in both in vitro and in vivo settings. Notably, this strategy showcased efficacy in mitigating anergic states, leading to a reduction in tumor growth and progression. Unfortunately, due to the incomplete replication of human stromal and tumor microenvironment in in vivo conditions, attributed to the absence of certain critical components, the stimulation of PD-L1 expression within the tumor mass mimics a hostile microenvironment. Remarkably, even with the administration of a limited number of cells, the anti-hPSMA CAR in combination with the haPD-1 demonstrated the capacity to overcome the inhibitory actions imposed by the tumor, exhibiting superior control over tumor growth compared to other CAR treatment conditions. Overall, this new approach is able to recognize and eradicate specifically tumors expressing the hPSMA, and simultaneously control the in vivo tumor progression of PD-L1 expressing tumors, paving the way to a more comprehensive ‘one-shot’ therapeutic approach. In conclusion, the integration of the anti-hPSMA CAR with haPD-1 presents a promising strategy for enhancing the precision and power of ACT against prostate cancer. This approach not only targets hPSMA-expressing tumors but also demonstrates versatility in controlling diverse tumor types, presenting an innovative therapeutic solution for prostate cancer management.