Results from a major new study just revealed at one of the biggest cancer meetings in the world could make an important difference for women who have just been diagnosed with ovarian cancer. The study found that women who took a PARP inhibitor drug called Zejula (also called niraparib) right after their chemotherapy at the beginning of their treatment regimen lived about five and a half months longer without their cancer getting any worse than the women who did not take Zejula. And for women who had a genetic characteristic in their ovarian cancer called “homologous recombination deficiency,” the benefit in progression-free survival was even bigger — about 22 months, compared with about 10 and a half months for those who didn’t take Zejula.
“It is likely that this will become the new standard of care for all women newly diagnosed with ovarian cancers,” Dr. Douglas Levine, a gynecologic oncologist at NYU Langone Health, told SurvivorNet. It’s important to note that the women in this study who benefitted from Zejula were those whose cancers had shown a response to platinum-based chemotherapy.
Read MoreRELATED: PARP Inhibitors Can Be Effective as Part of Initial Treatment for Ovarian Cancer
So, How Do PARP Inhibitors Work?
Poly ADP ribose polymerase (PARP) inhibitor drugs work by preventing cancer cells that have been damagedoften during the course of chemotherapy treatmentfrom naturally healing. To accomplish this, and, in turn, effectively kill the cancer cell, the PARP-inhibitor drug blocks the necessary mechanism of repair, the PARP enzyme, which the cancer cell requires to its broken DNA.
"The use of PARP inhibitors has really kind of exploded in ovarian cancer and it's very exciting," Dr. Ritu Salani, a gynecologic oncologist at Ohio State University Wexner Medical Center, told SurvivorNet in a previous conversation about PARP inhibitors.
The PARP inhibitors currently approved by the U.S. Food and Drug Administration (FDA) include Olaparib (Lynparza), Niraparib (Zejula), and Rucaparib (Rubraca). PARP inhibitors do have very significant side effects, and their ability to benefit women can vary greatly.
RELATED: Differences Between Types of PARP Inhibitors
Why Was the Benefit So Much Bigger for the Women With The Genetic Characteristic
When someone’s ovarian cancer cells have a genetic characteristic called “homologous recombination deficiency,” or “HRD,” that means that the cells already have a difficult time repairing themselves after damage (or at least, they have a more difficult time than cancers without HRD). Because the PARP inhibitors make the repair process even more difficult, cancers with HRD usually respond the best to PARP inhibitors. In this study, people with HRD who took Zejula lived almost double the amount of time without their cancers getting any worse than people who didn’t take Zejula. That’s a major improvement and one that could really change the game for these patients with ovarian cancer.
“PRIMA will clearly change the standard of care and move niraparib [Zejula] up into the front line maintenance setting,” Dr. Michael Birrer, a Professor at the University of Alabama Birmingham O'Neal Comprehensive Cancer Center told SurvivorNet, referring to how these PARP inhibitor drugs will likely become the go-to “maintenance” treatment (meaning after chemo, to keep the cancer from coming back) for women who have just been diagnosed with ovarian cancer.
Side Effects And Considerations With PARP Inhibitors
As more studies like this one continue to expand the group of women with ovarian cancer who can benefit from PARP inhibitors (and the experts say several other big studies are coming out soon), it’s important to pay attention to the side effects and other considerations that go along with these drugs.
“For some women, the toxicity [side effects] will outweigh the benefit,” Dr. Bobbie J. Rimel, an OB/GYN and oncologist at Cedars-Sinai Medical Center, told SurvivorNet, explaining that the fatigue that can come with PARP inhibitors is a serious and common side effect. In some cases, though, experts say the benefits of PARP inhibitors can outweigh the difficult fatigue.
“Despite the fact that some women have increased fatigue — partially, that’s because of the anemia that the drug causes — it is still worth that cost in the survival advantage that women are getting,” Dr. Rebecca Arend of the University of Alabama-Birmingham Comprehensive Cancer Center previously told SurvivorNet.
Dr. Emese Zsiros spoke with SurvivorNet about weighing the benefits of PARP inhibitors
And in a previous conversation about PARP inhibitors, Dr. Emese Zsiros, a gynecologic oncologist at the Roswell Park Cancer Institute told SurvivorNet that a lot of women who take PARP inhibitors experience nausea, vomiting, constipation, or diarrhea. Doctors are getting better at helping women manage these side effects every day, but sometimes they can be severe, making it important to talk to your doctor about whether they outweigh the benefits of the drugs.
RELATED: Side Effects of PARP Inhibitors
“We have to weigh the risk and benefit of prescribing these medications to our patients,” Dr. Zsirors said, adding that they aren’t cheap, either. “There is a significant financial toxicity when we prescribe these medications. I think there is a lot of cost-benefit ratio, and also there is a significant side effect.”
RELATED: Costs and Barriers to Getting PARP Inhibitors
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