Zentalis Pharmaceuticals reports 15.8‑month survival in ovarian cancer subgroup
The uncontrolled Phase 2 analysis used a September 2025 cutoff; Zentalis will present the survival data at ESMO on Oct. 23.
Adrian Kessler
Median survival reached 15.8 months among Cyclin E1-positive ovarian cancer patients as Zentalis Pharmaceuticals, Inc. NASDAQZNTL reported Phase 2 azenosertib data on Sunday. The 48-patient subgroup had platinum-resistant disease and received the investigational drug without a chemotherapy control.
The interim analysis used a Sept. 2, 2025 data cutoff, and the release does not give median follow-up. The survival estimate's 95 per cent confidence interval spanned 8.7 to 17.8 months.
Zentalis is a small San Diego oncology developer advancing an oral medicine that blocks a protein involved in cancer-cell division.
Shares fell 4.91 per cent to US$2.13 at Friday's 4:00 p.m. EDT Nasdaq close, according to NASDAQZNTL. That close preceded Sunday's release; the next clinical presentation is scheduled for Oct. 23.
The Survival Analysis Had No Chemotherapy Control
DENALI Part 1b enrolled 102 patients regardless of Cyclin E1 expression, after one to five prior treatment lines and prior bevacizumab. All received 400 milligrams of azenosertib once daily for five days followed by two days off.
Overall survival was a secondary endpoint; the primary endpoint was objective response rate, measuring tumour shrinkage. Sunday's release focuses on survival and provides no new primary-endpoint response figure.
Cyclin E1 status was determined retrospectively using Zentalis's proprietary tissue-test cutoff, with 94 patients evaluable. Median survival was 7.5 months among 46 Cyclin E1-negative patients. That estimate's 95 per cent confidence interval ran from 5.8 to 12.3 months.
Both biomarker groups received azenosertib, so the survival difference cannot establish an advantage over chemotherapy. The release's favourable comparison with historical chemotherapy benchmarks also lacks a concurrent control group.
No new safety signals were observed, according to Zentalis, although Sunday's release provides no adverse-event rates for this survival update.
The subsequent DENALI Part 2 prospectively selects patients for Cyclin E1 overexpression. Its expansion cohort has completed enrollment, while another cohort is enrolling patients previously treated with a taxane-containing regimen for platinum-resistant disease.
In its Aug. 6 regulatory update, Zentalis said the FDA had no objection to continued study of the selected dose. The agency acknowledged that the Part 2 population could potentially support accelerated approval, subject to the data's strength and the approved-treatment landscape when it acts.
"We expect to provide the topline readout of DENALI Part 2 in 1H 2027," Zentalis chief executive Julie Eastland said in the August release.
Zentalis held US$174.6 million in cash, cash equivalents and marketable securities at June 30. Management said that balance could fund operating expenses and capital expenditures into late 2027.
Randomized Trials Will Test Treatment Benefit
AbbVie NYSEABBV provides a randomized survival benchmark in a different biomarker-defined ovarian cancer population. Its March 15, 2025 MIRASOL update reported median survival of 16.85 months with Elahere versus 13.34 months with chemotherapy.
That analysis followed patients for a median 30.5 months and selected tumours expressing high levels of folate receptor alpha. Its eligibility rules differ from DENALI's, preventing a direct efficacy ranking from the survival medians.
Genmab A/S NASDAQGMAB reported on Oct. 3 that Rina-S produced a 45.9 per cent response rate in platinum-resistant ovarian cancer. That uncontrolled cohort treated 109 patients, with responses lasting a median 12.1 months among responders.
Read more: Genmab A/S reports 45.9 per cent Rina-S response in ovarian cancer trial
Zentalis's randomized Phase 3 ASPENOVA trial plans to enroll about 420 patients, comparing azenosertib with investigator-selected single-agent chemotherapy. Progression-free survival is its primary endpoint; overall survival is a key secondary measure.
The first-half 2027 Part 2 readout is intended to support accelerated approval if the data and regulatory discussions permit. Before that, the Oct. 23 ESMO rapid oral presentation will put DENALI's survival analysis before the congress.
