- Tesaro's PARP inhibitor niraparib showed significantly improved outcomes and extended life expectancy for recurrent ovarian cancer patients, according to its presentation at the European Society for Medical Oncology (ESMO) in Copenhagen over the weekend. PARP (poly ADP ribos polymerase) inhibitors block enzymes in repair DNA, helping to kill cancer cells.
- In the double-blind, placebo-controlled Phase 3 trial involving 553 patients, niraparib achieved not only primary endpoint but prolonged progression-free survival (PFS) compared to control patients. Niraparib also did not show worsening outcomes in a recurrent study of the patients with a BRCA mutation, a damaged gene that can lead to increased risk of cancer.
- As drug companies’ focus increases on PARP inhibitors for cancer treatments, the Massachusetts drug company is in a competitive battle with others, such as Clovis Oncology, AbbVie and Pfizer’s newly acquired Medivation.
Tesaro has been riding a positive wave since it reported reaching primary end points of a Phase 3 trial earlier this month, raising its hope that niraparib would be a new significant treatment for ovarian cancer. About 22,000 women are diagnosed each year in the U.S. with ovarian cancer and more than 65,000 annually in Europe. Ovarian cancer is the fifth most frequent cause of death among women.
Niraparib is directed toward lapses in the disease, which occur between cycles of platinum-based therapy, and prompts a recurrence among 85% of patients. Now with its successful Phase 3 Engot-Ov16/Nova trial reported at ESMO, it seals its plans to move quickly for regulatory approvals in the U.S., anticipated for the fourth quarter this year.
The Phase 3 trial of 553 patients, the company said, achieved its primary endpoint in two areas: it significantly prolonged PFS compared to control with germline BRCA mutation, (gBRCAmut) carriers. It also significantly prolonged PFS compared to control for the patient population with tumors deficient in homologous recombination (HRDpos).
In the primary endpoint results, the median PFS for patients treated with niraparib in the gBRCAmut cohort was 21 months, compared to 5.5 months with control. For the non-gBRCAmut cohort, the median PFS for patients treated with niraparib was 9.3 months, compared to 3.9 months for control. In addition those in the non-gBRCAmut cohort for patients with HRD-positive tumors, the median PRFS was 12.9 months, compared to 3.8 months for control.
"These landmark results are extremely encouraging for the ovarian cancer community," Mansoor Raza Mirza, the principal investigator on the ENGOT-OV16/NOVA trial and medical director of the Nordic Society of Gynecologic Oncology said in a statement. "The effectiveness of platinum-based chemotherapy, diminished over time and PFS and platinum-free intervals generally become shorter after each round of platinum treatment," he said.
The FDA has granted fast track designation for niraparib for the treatment of patients with recurrent platinum-sensitive ovarian fallopian tube or primary peritoneal cancer.
Jefferies analyst Eun K. Yang wrote in a note to investors that it is likely that niraparib will receive FDA approval in 2017, but questioned what kind of approval it may get, whether for broad label to cover all indications, or only for BRCAm. For the drug company, issues ahead may revolve around "statistical significance vs. clinical meaningfulness," Yang said.