Scientists have developed a method using a simple blood test to predict the duration of a prostate cancer patient’s response to the PARP inhibitor drug olaparib. This discovery, published in Cancer Cell, comes from researchers at The Institute of Cancer Research, London.

A strong link was found between the number of “reversion mutations” in a patient’s DNA and their survival time. Reversion mutations restore function to mutated genes involved in DNA repair.
After four months of olaparib treatment, patients with a high number of these mutations had an average survival time of 13.9 months, while those with a lower number lived an average of 21.4 months.
Olaparib works by preventing cancer cells from repairing their DNA.

The research focused on patients with advanced prostate cancer who had mutations in genes responsible for DNA damage repair, and who initially responded well to olaparib. The study found that olaparib treatment can actually cause some tumors to regain the ability to repair DNA, even in tumors missing the BRCA2 gene.
This finding is significant because it explains how resistance to the drug develops, and it may lead to the development of new treatments to prevent this resistance.

Being able to predict when and how patients will develop resistance to olaparib is critical for personalizing treatment strategies. Doctors can use this information to decide when to switch patients to different treatments, and researchers can focus on developing new therapies to target the specific mechanisms of resistance.

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