PARP Inhibitors Effective but Costly for Recurrent Ovarian Cancer

Niraparib is the most effective but most costly of the poly (ADP-ribose) polymerase (PARP) inhibitors currently approved by the US Food and Drug Administration (FDA) for the treatment of recurrent ovarian cancer.

The three current FDA-approved PARP inhibitors for the treatment of recurrent ovarian cancer include niraparib, rucaparib, and olaparib. Unlike approved intravenous therapies, Medicare is under no obligation to cover prescription medicines, noted Juliet Wolford, MD, of the University of California, Irving, at the 2017 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago (abstract 5516).

The researchers obtained individual drug costs and infusion charges from the Center for Medicare Services Drug Payment Table and Physician Fee Schedule, utilizing the direct costs. Billed charges and indirect costs were not included.

Separately, the PARP inhibitors were compared with intravenously administered drugs approved for recurrent ovarian cancers, including platinum and non–platinum-based treatments, and bevacizumab-based regimens. Toxicity and mean progression-free survival (PFS) rates for the different agents were obtained from registration trial data.

Costs of intravenous chemotherapy, managing toxicities, infusions, and supportive care were estimated using 2015 Medicare data. Incremental cost-effectiveness ratios (ICERs) were calculated and survival was reported in quality-adjusted life months.

Platinum-based combinations were the most cost-effective at $1,672/PFS month as compared to non-platinum agents ($6,688/month), bevacizumab-containing regimens ($12,482/month), olaparib ($16,469/month), and rucaparib ($16,781/month). Niraparib was the least cost-effective at $18,157/PFS with BRCA mutation and $18,253/PFS without BRCA mutation. 

Niraparib was the most effective, leading to 29.2 months PFS with mutation and 17.7 months with no mutation. Costs associated with PARP inhibitors were 7.1 to 8.3 times more than platinum combinations.

To better compare the registration trial data to PARP inhibitor data, probability was adjusted to second-line rucaparib, revealing its ICERs’ of per month of life added to be $27,117 for bevacizumab, $34,605 for non-platinum, and $96,930 for platinums. Using the adjusted-to-second-line probabilities for olaparib, exhibited ICERs were $25,562 for bevacizumab, $33,030 for non-platinums, and $88,119 for platinums.

Niraparib was not adjusted to second-line therapy as it was approved in maintenance for those who have had two prior treatments and were in a complete or partial response to the most recent chemotherapy treatment.

In conclusion, Wolford said: “While the data on the PARP inhibitors is promising, the unfortunate nature of new therapies is their inherent associated high costs reflecting the high costs of development. The primary expense of these therapies lie in the high cost of the drug, rather than the complications associated with their use.”

Minimal reductions in cost should have a great benefit in the cost-effectiveness of medications. “These reductions can be achieved through a variety of mechanisms mostly aimed at these therapies being more widely used, prompting an increased awareness and accessibility, and thus affordability of the treatments,” she said.

The high costs of PARP inhibitors were not balanced by costs of infusion and managing toxicities of intravenous drugs typically associated with lower response rates and shorter PFS in the recurrent space. “Balancing incremental clinical benefit with novel therapies remains problematic and could widen disparities among those with limited access to care,” said Wolford.