Thymopentin Enhances Antitumor Immunity Through Thymic Rejuvenation and T Cell Functional Reprogramming.

Background/

Objectives

T cell dysfunction represents a fundamental barrier to effective cancer immunotherapy. Although immune checkpoint blockades and adoptive cell transfer have achieved clinical success, therapeutic resistance remains prevalent across cancer types. Thymopentin (TP5), a synthetic immunomodulatory pentapeptide (Arg-Lys-Asp-Val-Tyr), has demonstrated immunostimulatory properties, yet its anticancer potential remains unexplored. The aim of this study was to investigate TP5's antitumor efficacy and underlying immunological mechanisms.

Methods

We evaluated TP5's therapeutic effects in multiple murine tumor models, including B16-F10 melanoma, MC38 colorectal carcinoma, Hepa 1-6, and LM3 hepatocellular carcinoma. Immune cell populations and functional states were characterized using flow cytometry, ELISAs, and immunofluorescence analyses. The potential of TP5 as an adjuvant for T cell-based therapies was also systematically assessed.

Results

The TP5 treatment markedly suppressed tumor growth across caner models through strictly T cell-dependent mechanisms. Critically, TP5 promoted thymic rejuvenation under immunocompromised conditions, restoring the thymus-tumor immunological balance and revitalizing peripheral T cell immunity. TP5 functionally reprogrammed T cell states, preserving effector function while ameliorating exhaustion. Furthermore, TP5 demonstrated synergistic efficacy when combined with adoptive T cell therapies, enhancing both proliferation and effector functions.

Conclusions

TP5 represents a promising immunomodulator that addresses fundamental limitations of current T cell therapies by simultaneously enhancing T cell function and reversing thymic involution under immunocompromised conditions. Our findings provide compelling evidence for TP5's clinical translation in cancer treatment.