---
title: "Zentalis to Present Phase 1b MUIR Data: 39% ORR, 7.3‑month PFS; 50% ORR at 250 mg Cohort"
type: "News"
locale: "en"
url: "https://longbridge.com/en/news/287276070.md"
description: "Zentalis reported Phase 1b MUIR data showing a 39.1% overall response rate (ORR) and a 7.3-month median progression-free survival (PFS) for azenosertib plus paclitaxel in platinum-resistant ovarian cancer. The 250 mg cohort demonstrated a 50% ORR. Safety was manageable with common adverse events including fatigue and anemia. Results will be presented at ASCO 2026."
datetime: "2026-05-21T21:33:00.000Z"
locales:
  - [zh-CN](https://longbridge.com/zh-CN/news/287276070.md)
  - [en](https://longbridge.com/en/news/287276070.md)
  - [zh-HK](https://longbridge.com/zh-HK/news/287276070.md)
generator: "portal-rs"
---

# Zentalis to Present Phase 1b MUIR Data: 39% ORR, 7.3‑month PFS; 50% ORR at 250 mg Cohort

**Zentalis reported Phase 1b MUIR data showing 39.1% ORR and a 7.3‑month median PFS for azenosertib plus paclitaxel in platinum‑resistant ovarian cancer.**

**Key Highlights:**

-   Data from Part 1 (n=46, cutoff Dec 1, 2025) to be presented at ASCO 2026; paclitaxel arm poster on June 1.
-   All‑comer PROC results: ORR 39.1% (95% CI 25.1–54.6), CBR 58.7%, median PFS 7.3 months.
-   250 mg intermittent (5:2) cohort (n=12) showed ORR 50.0% (one CR) and median DOR 9.2 months.
-   Manageable safety across cohorts: common TRAEs fatigue, anemia, nausea, neutropenia; Grade ≥3 neutropenia 30.4%.
-   Clinical activity similar in Cyclin E1‑positive and ‑negative tumors, suggesting biomarker may not be required in combination setting.

Original SEC Filing: Zentalis Pharmaceuticals, Inc. \[ ZNTL \] - 8-K - May. 21, 2026

**Disclaimer**

This is an AI-powered summary. It may contain inaccuracies. Consider verifying important information with the source. Please note this summary is solely based on documents filed with the SEC.

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---
> **Disclaimer: This article is for reference only and does not constitute any investment advice.**