The highlight of the upcoming ESMO 2019, a cancer meeting in Europe, will be heated competition among PARP inhibitors -- pharmacological inhibitors of the enzyme poly ADP-ribose polymerase (PARP) -- in the ovarian cancer treatment.

European Society for Medical Oncology (ESMO) will hold an annual meeting from Sept. 27 to Oct. 1 in Barcelona, Spain, where pharmaceutical firms will announce the results of trials on PARP inhibitors in first-line maintenance treatment for metastatic ovarian cancer.

The PAOLA-1 study of AstraZeneca’s Lynparza (ingredient: olaparib) is drawing the most attention from the pharmaceutical industry. Lynparza is the first PARP inhibitor, dominating the PARP inhibitor market with the broadest scope of indication.

However, Takeda’s Zejula (niraparib) with sales rights owned by GSK has become a dark horse for rival products, including Lynparza. While only 15 percent of ovarian cancer patients have BRCA mutations, Lynparza and other PARP inhibitors work only for patients with BRCA mutation. In contrast, Zejula can be used not only for the 15 percent of patients but the rest 85 percent of non-BRCA patients.

Takeda recently disclosed topline results of the PRIMA study of Zejula, saying it showed meaningful therapeutic effect in the first-line maintenance treatment in metastatic ovarian cancer. The study on Zejula pressured Lynparza, but AstraZeneca hit back, saying the PAOLA-1 study on Lynparza also showed efficacy regardless of BRCA mutation.

While the PRIMA trial compared Zejula with placebo in first-line maintenance treatment in metastatic ovarian cancer, the PAOLA-1 study compared a combination therapy of Lynparza and Avastin (bevacizumab) to Avastin alone.

In Korea, Lynparza has an upper edge because Avastin is reimbursable.

However, in the U.S., the world’s largest pharmaceutical market, only 25 percent of ovarian cancer patients use Avastin as first-line maintenance therapy. Considering the issue of toxicity and additional costs of Lynparza and Avastin combo, Zejula could be more beneficial, some experts said.

Detailed data to be read out at the upcoming Europe meeting will be the key to predict which drug will perform better in the ovarian treatment market.

AbbVie also plans to release data of its PARP inhibitor. The company has failed to prove veliparib’s efficacy in non-small cell lung cancer and triple-negative breast cancer. However, the company said in July that its Velia study on veliparib plus chemotherapy was positive in improving progression-free survival.

All of these data are scheduled to be revealed on Sept. 28, the second day of the meeting, drawing keen attention.

Takeda’s Zejula received approval here as a second-line maintenance treatment for metastatic ovarian cancer in March. The Health Insurance Review and Assessment Service’s Drug Reimbursement Evaluation Committee recently ruled that the drug could get insurance benefit. The company is negotiating a drug price with HIRA.

Although Zejula can be used regardless of BRCA mutation, the health authorities are reportedly to grant reimbursement for BRCA patients only, just like Lynparza.

“The authorities are indeed likely to limit the scope of reimbursement for Zejula to patients with BRCA mutation only,” said Takeda Pharmaceutical Korea CEO Moon Hee-seok. “We feel somewhat sorry, but once we get the benefit, we will try to expand the scope of reimbursement next year.”

kym@docdocdoc.co.kr

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