Half of ovarian cancer patients in a small study responded to a combination of Tesaro’s Zejula and Genentech’s Avastin, according to a presentation Tesaro made at the European Society of Medical Oncology (ESMO) 2017 Meeting in Madrid.
It was one of a host of presentations the company delivered on Zejula (niraparib) and another of its ovarian cancer therapies, TSR-042. The conference ran from Sept. 8-12.
Among the highlights were trials exploring combinations of Zejula — approved in the U.S. in March 2017 as a maintenance therapy for women with ovarian cancer — and cancer immunotherapy drugs. Another intriguing presentation was a study suggesting that watchful waiting after a chemotherapy round for ovarian cancer is a bad treatment approach.
“Zejula is the market-leading PARP inhibitor, with unsurpassed efficacy in a broad patient population and convenient, once-daily dosing,” Mary Lynne Hedley, president and chief operating officer of Tesaro, said in a press release.
The drug was the focus of no fewer than six presentations. Several reported data from the Phase 3 NOVA trial (NCT01847274) in which women who had completed chemotherapy received Zejula as a maintenance therapy.
The trial showed that many patients experience residual symptoms after chemotherapy. Zejula did not improve patient-reported outcomes or quality of life, the trial indicated. It did show that the drug is equally safe in younger and older patients, and that the maximum dose of Zejula can be individualized.
Dosing was also the topic of a study in patients with moderately severe kidney or liver disease. Researchers had used data from the NOVA trial and a Phase 1 study of the drug to model how it behaved in the body. Findings suggested that patients with moderate kidney or liver disease can receive the same doses as other patients.
Two studies homed in on combinations. The Phase 1/2 AVANOVA study (NCT02354131) looked at Avastin (bevacizumab) plus Zejula in women who had responded to platinum chemotherapy.
Although preliminary, results of the first part of the study showed a disease control rate of 92 percent, with half of the 12 treated patients responding to the combo. The disease control rate is the percentage of patients who achieve a full response, partial response or stable disease with a treatment.
The combo was also safe, with no surprise side effects caused by combining the two drugs.
The second study — the Phase 1/2 TOPACIO trial (NCT02657889) — combined Merck’s Keytruda (pembrolizumab) with Zejula in a more difficult to treat group: ovarian cancer patients who were resistant to platinum chemotherapy or who had triple negative breast cancer.
In the Phase 1 portion of the study, five of the nine patients responded to the combo, and four achieved a stable disease. The Phase 2 part is continuing. So far, safety evaluations have shown side effects consistent with earlier studies of the two treatments.
Tesaro also presented findings on its investigational checkpoint inhibitor TSR-042, which targets the programmed cell death protein 1, or PD-1. Checkpoint inhibitors release a brake on the immune system, allowing it to attack a tumor.
The Phase 1 part of the study (NCT02715284) covered 21 patients with various solid tumors who had had a number of treatments before TSR-042. Two patients with ovarian cancer or lung cancer had a partial response, and the ovarian or fallopian tube cancer of five others stabilized.
Researchers also looked at outcomes of women placed on watchful waiting — a period without treatment after chemotherapy for ovarian cancer. Results suggested the approach was far from optimal, with 30.1 percent of patients having to be hospitalized and 27.4 percent having to seek emergency care.
“‘Watchful waiting’ is no longer an acceptable option for women living with ovarian cancer,” Hedley said. “We believe combination approaches, including niraparib and anti-PD-1 antibodies, will become increasingly important, and we are executing on our registration strategy for TSR-042, our anti-PD-1 antibody, in MSI-high [microsatellite instability high] cancers.”