Radiotherapy-Poly(ADP-ribose) Polymerase Inhibitor Combinations: Progress to Date

Area of Science:

• Oncology
• Radiation Biology
• Molecular Biology

Background:

• Radiation resistance is a significant clinical challenge in cancer therapy.
• The DNA damage response (DDR) is crucial for cellular survival after radiation exposure and is often dysregulated in cancer.
• Targeting aberrant DDR pathways in tumors may enhance radiotherapy efficacy.

Purpose of the Study:

• To review the role of Poly(ADP-ribose) polymerase (PARP) in the cellular response to ionizing radiation.
• To summarize preclinical studies on PARP inhibitors (PARPi) as radiosensitizers.
• To explore current clinical trials evaluating PARPi in combination with radiotherapy.

Main Methods:

• Review of existing literature on PARP, DDR, and PARPi.
• Analysis of preclinical data on PARPi as radiosensitizers.
• Summary of findings from early-phase clinical trials of PARPi and radiation therapy.

Main Results:

• PARPi inhibit DNA single-strand break repair and may radiosensitize hypoxic cells.
• PARPi can target alternative DNA repair pathways like microhomology-mediated end joining, which are upregulated in cancer.
• Early clinical trials indicate tumor-specific challenges in tolerability, largely consistent with preclinical predictions.

Conclusions:

• PARPi represent a promising strategy to overcome radiation resistance by modulating the DDR.
• Combination therapy with PARPi and radiotherapy has shown potential but requires careful management of treatment-related toxicities.
• Further clinical investigation is warranted to optimize the use of PARPi in cancer radiotherapy.