With Positive Phase III Data, Junshi's PARP Inhibitor could Challenge Lynparza

Pictured: micrograph of a uterine biopsy/iStock

Pictured: micrograph of a uterine biopsy/iStock

Junshi Biosciences is gearing up to challenge AstraZeneca and Merck in the PARP inhibitor market. The Chinese biotech announced Tuesday that its ovarian cancer candidate, senaparib, met the primary endpoint in a Phase III interim analysis. 

Partnered with IMPACT Therapeutics, senaparib is the first domestically developed PARP inhibitor to prove efficacy in advanced ovarian cancer as a second-line therapy, Jianjun Zou, president of global research and development at Junshi, stated in the press release.

Senaparib was studied as a maintenance treatment following platinum-based chemotherapy in stage III/IV ovarian carcinoma, fallopian tube cancer or primary peritoneal cancer patients who achieved a complete response or partial response.

Interim data from the Phase III study showed senaparib significantly extended progression-free survival of advanced ovarian cancer patients “regardless of the patient’s breast cancer susceptibility gene (BRCA) mutation status,” Zou said.

Junshi and IMPACT plan to discuss a New Drug Application with regulatory authorities in the near future, according to the announcement.

A Troubled Market

Poly adenosine diphosphate-ribose polymerase (PARP) inhibitors are currently approved for types of ovarian, metastatic breast and pancreatic cancer. Blocking PARP can prevent DNA repair in cancer cells, keeping them from multiplying.

AstraZeneca and Merck brought the first PARP inhibitor to the U.S. market in 2014 when the FDA approved Lynparza (olaparib) for patients with BRCA-mutated metastatic ovarian cancer. The drug is estimated to bring in $9.7 billion by 2028.

Clovis Oncology and GSK also have PARP inhibitors on the market for ovarian cancer with Rubraca (rucaparib) and Zejula (niraparib), respectively. 

In 2022, the PARP inhibitor market took a bit of a hit as all three manufacturers withdrew indications for heavily pretreated patients with BRCA-mutated ovarian cancer due to safety concerns.

The FDA had planned an advisory committee meeting for Zejula in November but canceled after GSK complied with the FDA’s request to restrict its use to BRCA-positive patients. Emerging data suggests non-BRCA patients on the drug were at increased risk of death versus control.

Ovarian cancer is often not found until the advanced stages and carries with it a median five-year survival rate of only 40% for the roughly 310,000 patients diagnosed globally each year.

Kate Goodwin is a freelance life science writer based in Des Moines, Iowa. She can be reached at kate.goodwin@biospace.com and on LinkedIn.

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