Mahon on the Benefits and Challenges of PARP Inhibitors in Ovarian Cancer Treatment

Lauren Mahon, MSN, FNP-BC

It is important for nurses to understand the importance of genetic testing when determining which patients with ovarian cancer are eligible for treatment with PARP inhibitor, according to Lauren Mahon, MSN, FNP-BC.

“Doing genetic testing is really important,” she told Oncology Nursing News®. “[It is key] for us to identify who is eligible for PARP inhibitors, to increase the progression-free survival [for] our patients.”

Mahon, who is a family nurse practitioner specializing in gynecologic oncology at the University of Rochester, recently presented on this class of agent during the 48th Annual Oncology Nursing Society Congress, in an interview after the presentation, she discussed the potential benefit of oral maintenance therapies with the 3 FDA-approved PARP inhibitors, niraparib (Zejula), olaparib (Lynparza), and rucaparib (Rubraca) and important nursing considerations with these agents.

Oncology Nursing News: What are the advantages of oral treatments, especially in the maintenance setting, and what are some of the disadvantages?

Mahon: PARP inhibitors have given patients more options in the maintenance therapy [setting].

Oral medications, in general, give you more flexibility. Patients have their quality of life back [because] they’re not tied to an IV every 3 to 4 weeks. They can go and travel, they can spend time with their family members—they are able to enjoy those things.

A disadvantage of oral medications, of course, is medication adherence. Some individuals forget to take their oral medications.

Also with oral medications, we need to see patients typically every 4 weeks. Some patients, because they’re on oral treatments, think they do not have to come in. It is important for us to educate our patients—because [these agents] do have significant adverse effects—to make sure that they are coming to their appointments so we can assess for those.

What is the importance of genetic testing?

Genetic testing is very important for PARP inhibitors. To see who is eligible for these PARP inhibitors, we do germline testing where we test the patient’s DNA to see if they have the BRCA1 or BRCA2 gene mutation that makes them eligible for PARP inhibitors. If they do not have those gene mutations with germline testing, we do somatic testing [where] we test the tumor DNA. Homologous repair deficient tumors have the BRCA1 or BRCA2 mutation and those can represent up to 15% of serous ovarian cancers. That’s a significant [percentage of the] population that could be eligible for PARP inhibitors.

Could you discuss some of the different safety profiles for the different approved PARPs? What are the differences that you might need to know in caring for patients who are receiving these different treatments?

PARP inhibitors do have some similar adverse effects as the IV chemotherapy. Fatigue is a big one, [along with] nausea, vomiting, and changes in bowel habits.

They all [can] have hematologic toxicities, but the main PARP inhibitor that causes anemia and thrombocytopenia is niraparib. If your patient struggled with that on IV chemotherapy, niraparib might not be a great option for them. If niraparib is the only 1 they can have, whether for insurance purposes or [another reason], we dose reduce niraparib from the very beginning and we monitor them very closely.

With any PARP inhibitor, we need to do weekly laboratory tests for the first month, just to make sure that these [results] are stable, and the patient can still safely take them. Rucaparib has been shown to increase serum creatinine levels, so it’s important if your patient already has that elevation to really monitor that closely. Olaparib has that [risk] as well. Niraparib has not been shown to increase serum creatinine so in patients with those adverse effects already after IV chemotherapy, it might be a good idea to consider niraparib.

Reference

Mahon L. PARP-inhibitors role in the treatment of ovarian cancer. Poster presented at: 48th Annual Oncology Nursing Society Congress; April 26-30, 2023; San Antonio, TX. Accessed June 20, 2023. https://ons.confex.com/ons/2023/meetingapp.cgi/Paper/12181