Zentalis survival data released on October 18, 2026, showed median overall survival of 15.8 months in patients with Cyclin E1-positive platinum-resistant ovarian cancer treated with investigational azenosertib. The interim DENALI Part 1b findings have been published in an ESMO Congress abstract, ahead of a scheduled October 23 presentation.
Key Takeaways
- Median overall survival was 15.8 months in the Cyclin E1-positive subgroup and 7.5 months in the negative subgroup.
- Both subgroups received azenosertib; the comparison does not establish a survival benefit over chemotherapy.
- Azenosertib remains investigational, with further development focused on biomarker-selected patients.
Table of Contents
- Zentalis survival data distinguish two biomarker subgroups
- What the findings establish—and what they do not
- Later-stage trials remain central to the development path
- Conclusion
Zentalis survival data distinguish two biomarker subgroups
The company’s DENALI Part 1b survival announcement reports an interim analysis using a September 2, 2025 data cutoff. Overall survival was a secondary endpoint, while the study’s primary endpoint was objective response rate, a measure of tumor response.
The Cyclin E1-positive analysis included 48 patients, compared with 46 in the Cyclin E1-negative subgroup. Zentalis reported no new safety signals at the cutoff; that finding does not mean the treatment is free of adverse effects.
The study enrolled 102 patients regardless of Cyclin E1 protein expression. Biomarker status was determined retrospectively using immunohistochemistry and a company-defined cutoff, with 94 patients evaluable for that assessment.
| Item | Details |
|---|---|
| Cyclin E1-positive survival uncertainty | 95% confidence interval: 8.7–17.8 months |
| Cyclin E1-negative survival uncertainty | 95% confidence interval: 5.8–12.3 months |
| Prior treatment requirements | One to five previous lines of therapy; prior bevacizumab required |
| Part 1b dosing | 400 mg once daily for five days, followed by two days without azenosertib |
What the findings establish—and what they do not
The survival difference supports Zentalis’s focus on Cyclin E1-positive patients in its development program. However, these are subgroups receiving the same investigational drug, not a randomized comparison of azenosertib against chemotherapy. The figures therefore do not establish how much survival benefit the drug provides over standard treatment.
Zentalis said the abstract compared survival favorably with historical single-agent chemotherapy benchmarks. Such comparisons are not equivalent to a head-to-head trial, and the interim results remain distinct from regulatory approval.
Other study details help define the population and the uncertainty around the survival estimates.
Later-stage trials remain central to the development path
DENALI Part 2 is prospectively enrolling patients with Cyclin E1 protein overexpression. Enrollment in the Part 2b expansion cohort is complete, while Part 2c, which broadens eligibility to patients previously treated with a taxane-containing regimen for platinum-resistant ovarian cancer, is enrolling.
The company says Part 2 is designed to support accelerated approval, subject to positive outcomes and further FDA discussions. That is a development objective, not an approval commitment.
The Phase 3 ASPENOVA confirmatory trial is designed to compare azenosertib with investigators’ choice of single-agent chemotherapy in approximately 420 Cyclin E1-positive patients. Its primary endpoint is progression-free survival, with overall survival among the key secondary endpoints.
Conclusion
The interim findings add survival evidence to Zentalis’s biomarker-focused azenosertib program without resolving comparative efficacy or approval prospects. The next scheduled event is the rapid oral presentation at ESMO Congress in Madrid on October 23, 2026.
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