Need to know:
- Unlike many other chemotherapy drugs, PARP inhibitors are given in pill form, and can be safely administered during the COVID-19 pandemic, since patients can take the drugs in their own homes, limiting their contact with others.
- But the drugs’ side effects, which can include suppressing the immune system, can present risks
PARP inhibitors have become an important treatment for ovarian cancer. This class of drugs works by targeting cancer’s genetic material, preventing the cells from repairing themselves.
Read MoreWho Can Take PARP Inhibitors?
While initially women with a BRCA-1 or BRCA-2 genetic mutation had been shown to respond especially well to PARP inhibitors after recurrence, newer research has shown that women with the BRCA gene mutation (and indeed almost all women), can consider using PARP inhibitors throughout their treatment. The Food and Drug Administration has approved Zejula (niraparib) for almost all women regardless of whether they have the BRCA mutation, as part of an initial course of treatment, or what's called front-line treatment. The PARP inhibitor Lynparza (olaparib) is approved for women newly diagnosed with ovarian cancer and with a germline or somatic mutation in BRCA1/2. Lynparza is also approved in combination with Avastin (bevacizumab) for women with HRD. Avastin is a blood vessel growth inhibitor, which works by starving the tumor of vital nutrients needed to grow.The American Society of Clinical Oncology (ASCO) guidelines recommend PARP inhibitors be offered to women, with or without genetic mutations, who are newly diagnosed with stage III or IV ovarian cancer and have improved with chemotherapy.
However, Dr. Amanika Kumar of the Mayo Clinic who spoke to SurvivorNet, cautioned that women still need to speak with their doctor to evaluate the benefit of taking a PARP inhibitor to extend life, because there are very real side effects due to the toxicity of the drug.
"Patients with HRD (homologous recombination deficiency) have a far better response than those without and those with BRCA mutations even more so. It is on us as clinicians to help patients understand the risks and benefits of treatment. Patients that have no mutation or HRD may choose not to go on maintenance (in fact I recommend they don't) because there is real toxicity to these meds."
Unfortunately, too often, ovarian cancer comes back.
For women with ovarian cancer who have had a recurrence and responded to platinum-based chemotherapy, Lynparza, Zejula and another PARP inhibitor called Rubraca (rucaparib) are FDA approved for use as a maintenance therapy, regardless of whether a woman has a BRCA mutation or HRD.
For some women who have had prior chemotherapy treatments, Rubraca, Zejula or Lynparza may also be options. These uses are based on factors such as number of prior therapies and BRCA mutation or HRD.
Side Effects
PARP inhibitors can cause serious side effects, and these are especially important to consider in the era of COVID-19. “The important thing for patients to understand is that PARP inhibitors can initially cause immunosuppression,” warns Dr. Nick.
This primary immunosuppression can put patients at a greater risk of infection because PARP inhibitors are affecting their blood counts. This relative degree of immunosuppression can be overcome for patients who take PARP inhibitors for a longer period of time since their blood counts begin to stabilize.
However, it is still necessary for them to exercise caution to prevent infections by diseases like COVID-19. Other side effects from PARP inhibitors include neutropenia, anemia, and thrombocytopenia.
Telemedicine
“We are still prescribing PARP inhibitors and doing our best to keep patients distanced from the office,” says Dr. Nick.
It’s important for doctors to be able to monitor their patients’ reactions to PARP inhibitors while also reducing the patient’s risk of infection as much as possible. This is more difficult for cancer patients in the early phase of treatment, when blood counts need to be monitored more frequently. These patients are usually asked to show up in person to get their labs run.
Afterwards, the cancer team can set up a virtual meeting for the patient to go over the results, avoiding another in-person office visit. These distancing measures allow doctors to safely monitor patients and adjust treatments.
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