Insights from a 30-year journey: function, regulation and therapeutic modulation of PD1

Area of Science:

• Immunology
• Molecular Biology
• Oncology

Background:

• Programmed cell death protein 1 (PD1) was initially identified in 1992, linked to T cell activation-induced cell death.
• Over three decades, PD1's role shifted to preventing excessive T cell death and autoimmunity.
• PD1 inhibition has emerged as a key strategy for activating anti-cancer immunity.

Purpose of the Study:

• To trace the historical trajectory of PD1 research from discovery to its current status in cancer immunotherapy.
• To elucidate the regulatory mechanisms and functional significance of PD1 signaling.
• To explore how PD1's role in setting the T cell activation threshold informs combination therapy development.

Main Methods:

• Review and synthesis of existing literature on PD1 discovery, function, and therapeutic applications.
• Analysis of PD1 signaling pathways and their impact on T cell behavior (proliferation, differentiation, exhaustion, metabolism).
• Examination of T cell metabolism and microbiota interactions in the context of PD1-targeted therapies.

Main Results:

• PD1 plays a central role in modulating the T cell activation threshold, influencing T cell fate and function.
• Understanding PD1 signaling, T cell metabolism, and microbiota modulation offers insights for novel combination therapies.
• Mechanisms of immune-related adverse events associated with PD1-targeted therapy are discussed.

Conclusions:

• PD1 is a pivotal target in cancer immunotherapy, with its inhibition crucial for unleashing anti-cancer immunity.
• A mechanistic understanding of PD1 signaling provides a framework for developing more effective combination treatments.
• Further research into PD1, T cell metabolism, and the microbiome is essential for optimizing cancer therapy and managing side effects.