More is Not Better - Reducing Ovarian Cancer Treatment

A common medication for maintenance therapy of ovarian cancer can be reduced without sacrificing effectiveness.

The medication in question is called a PARP inhibitor. PARP inhibitors are a class of drugs that targetcancer cells in people with mutations in genes involved in repairing DNA. This approach is used in a maintenance situation - that is after surgery associated chemotherapy or radiation therapy - for people who have ovarian cancer who also have an inherited mutation in either BRCA1 or BRCA2. However, these PARP inhibitors can be associated with some unintended side effects.

One way to lessen side effects of treatments is to reduce the dose of the treatment medication. Before lowering doses, it is important to understand whether dose reductions decrease the effectiveness of the therapy and to identify the factors that cause dose reductions. One study that examined this situation was the recent SOLO2 trial.

In the SOLO2 trial, researchers looked at whether people who had recurrent ovarian cancer and an inherited BRCA1 or BRCA2 mutation benefited from the PARP inhibitor olaparib. Participants took either the PARP inhibitor olaparib or a placebo after chemotherapy. Researchers then look at how participants were doing 12 and 24 weeks later.

Participants who received olaparib had longer periods before their cancer progressed and better overall survival than those who received a placebo. This meets the primary goal of the SOLO2 trial by showing that olaparib treatment does benefit those with ovarian cancer.

However, almost all participants who received olaparib during SOLO2 experienced adverse effects that resulted in dose interruption, reduction or discontinuation. To understand this impact better, researchers asked whether SOLO2 participants who had reduced doses of olaparib had different outcomes than those without dose changes.

After 24 weeks of treatment, progression or overall survival among those with olaparib dose reductions was similar to those without dose reductions. This initial research is encouraging. However, further follow up is needed to understand if this holds up for longer time after treatment and to better understand the implications of modifying olaparib maintenance therapy to manage side effects.

Read more about the SOLO2 trial in our XRAY review.