Recent approvals for Corcept Therapeutics and Merck have injected momentum into the space, where GSK, Allarity Therapeutics, OSE Immunotherapies and others are advancing their own candidates.
The market for drugs designed to treat the deadliest gynecological malignancy—ovarian cancer—is gaining steam, thanks to two recent approvals and a crop of novel candidates in earlier-stage trials.
In February, Merck secured an FDA approval for Keytruda and subcutaneous injection Keytruda Qlex with paclitaxel for patients with platinum-resistant ovarian cancers (PROC). The addition of the blockbuster immunotherapy led to a 24% reduction in the risk of death, according to Phase 3 trial data. The agency then approved Corcept Therapeutics’ glucocorticoid blocker Lifyorli in PROC in March, with recent data showing a 35% reduction in the risk of death in combination with nab-paclitaxel compared to chemotherapy alone.
Both approvals were huge wins, particularly for platinum-resistant ovarian cancer, where treatment options are limited, said Premal Thaker, the WashU Medicine director of gynecological oncology clinical research at Siteman Cancer Center.
Thaker is the principal investigator on the Phase 3 OVATION-3 trial, which is evaluating a gene therapy from Imunon called IMNN-001 that is designed to boost levels of IL-12 and change the tumor microenvironment, alongside chemotherapy. Phase 2 data reported in March showed a 14.7-month increase in overall survival compared to standard of care chemotherapy.
IMNN-001 is one of several candidates bringing new interest to a stubborn disease with a relative 5-year survival rate of 52% and limited treatment options. “A lot of drugs have gone into trials for many, many decades, and we just haven’t had the same success that we’re seeing right now,” Thaker told BioSpace. “It’s smarter drugs and medications.”
Here are four candidates, each with a different mechanism of action, that the field is watching.
Make way for GSK’s Mo-Rez and the ADCs
The biggest frontrunners poised to make a dent in ovarian cancer are antibody-drug conjugates (ADCs), where AbbVie’s folate receptor antagonist Elahere is first-in-class.
Another candidate with recent data is GSK’s mocertatug rezetecan, or Mo-Rez, a novel ADC that targets an antigen called B7-H4 and carries a topoisomerase inhibitor payload. In its Phase 1 dose-escalation trial, BEHOLD-1, Mo-Rez had a confirmed objective response rate (cORR) of 62% in patients with PROC and 67% in those with endometrial cancer, according to data presented at the Society for Gynecological Oncology’s annual meeting in April.
“We were pretty happy with that,” Eric Richards, senior vice president and head of medicine development leaders for oncology at GSK, told BioSpace. “What we’re seeing is not only a high level of clinical activity but initial signs of pretty good durability.”
Richards added that the immune checkpoint protein B7-H4 is overexpressed in the vast majority of ovarian cancer cells, making it an attractive target. GSK is launching five Phase 3 trials evaluating Mo-Rez this year across ovarian and endometrial cancers, including BEHOLD-Ovarian01 in PROC and BEHOLD-Ovarian02 in platinum-sensitive ovarian cancer.
Elsewhere, German biotech Tubulis, recently acquired by Gilead, also recently reported positive results from a Phase 1 trial evaluating its ADC, TUB-040, in PROC. And Daiichi Sankyo and Merck are progressing their candidate raludotatug deruxtecan (R-Dxd) in a Phase 2/3 trial.
It’s too early to say which candidates look most promising, Thaker said, adding that many of them carry the same topoisomerase payload.
Their side effects will likely be a differentiating factor, she said. “It’s a little bit of a scientific conundrum right now—how are we going to sequence these? Because they all look very exciting.”
Zentalis chases a new target in WEE1
Zentalis Pharmaceuticals, meanwhile, is enrolling a Phase 3 global trial evaluating its novel inhibitor azenosertib in patients with cyclin E1–positive PROC against standard single-agent chemotherapy, according to a May press release.
Azenosertib is designed to inhibit the protein kinase WEE1, a master regulator of cell cycle checkpoints. At the 2026 American Society of Clinical Oncology annual meeting, data from the Phase 1b MUIR trial showed that azenosertib plus paclitaxel resulted in an ORR of 39% and a median progression-free survival (PFS) of 7.3 months in an all-comer PROC population. Both the cyclin E1-positive and negative groups had similar responses, the trial found.
The FDA granted Fast Track designation to the drug in January 2025 for patients who are positive for the cyclin E1 protein, which is overexpressed in around half of PROC patients. Ovarian cancer tumors positive for cyclin E1 are often especially hard to treat, Thaker noted.
“It’s nice that we’re developing a medication that can help overcome that,” Thaker—who is also involved in the research—said. Plus, she added, the azenosertib pill might be easier to take than some of the ADCs, which are delivered via infusions.
OSE’s proof-of-concept for cancer vaccines
More positive ovarian cancer data at ASCO 2026 came from OSE Immunotherapeutics, which reported Phase 2 results for its off-the-shelf vaccine Tedopi (OSE2101), designed to stimulate a patient’s T cells and target five different tumor-linked antigens.
In the TEDOVA trial, some 185 patients with platinum-sensitive recurrent ovarian cancer (PSOC) were randomized to Tedopi, Tedopi plus pembrolizumab or best supportive care as maintenance treatment after chemo. Patients in the trial were also required to be HLA-A2 positive, which shrinks the number of potentially eligible patients, Thaker said. “We have to be mindful when we look at some of these targets, we have to cut the pie a little bit more.”
With a median follow-up of 22 months, patients on Tedopi and pembrolizumab experienced a median PFS of 4.1 months, compared to 2.8 months for those getting the best supportive care. The addition of pembrolizumab to Tedopi led to a 28% reduction in the risk of progression or death, compared to Tedopi alone, the trial found, though that result missed the mark for statistical significance.
The results are the first proof of concept for a therapeutic vaccine in ovarian cancer and the first positive trial for PSOC in years, Alexandra Leary, deputy head of the department of medical oncology at Gustave Roussy in France and lead investigator on the trial, said in a press release.
Allarity’s next generation PARP inhibitor
Allarity Therapeutics’ stenoparib is another candidate with FDA Fast Track designation.
The drug is a dual-target inhibitor that homes in on PARP 1/2 and tankyrase 1/2, differentiating it from earlier PARP inhibitors such as AstraZeneca and Merck’s Lynparza and GSK’s Zejula.
Inhibiting tankyrase can disrupt signaling in the WNT pathway, which has been implicated in multiple cancers, Jeremy R. Graff, president and chief developmental officer at Allarity, told BioSpace. “It really seems to be particularly highly activated in really advanced, chemo- and radio-resistant cancers.”
Allarity licensed stenoparib in 2017 from Eisai based on the drug’s Phase 1 data. In Phase 2 data reported in September 2025, the median overall survival had not been reached at 25 months for patients with platinum-resistant and refractory ovarian cancer. The drug appeared to benefit patients regardless of their BRCA status, Graff added.
The company is expanding its Phase 2 trial for patients with PROC and has amended its trial protocol to focus on advanced, recurrent, platinum-resistant or platinum-ineligible ovarian cancer. Like with Zentalis’s azenosertib, the pill will likely be easier to take with milder toxicities than the ADCs, Graff said, which could be particularly helpful for older women.
Ovarian cancer hasn’t historically garnered as much attention as cancers with the biggest patient pools, including breast or prostate cancer, Graff said. But the hard-to-treat disease is now capturing more interest.
“It’s a huge unmet medical need,” Graff said. “We’d love to, with the era of targeted therapies, go beyond just poisoning people with chemotherapy.”
