Clinical Efficacy Analysis Report of Zenitar Biosciences' Puyistat Mesylate (PM) for Relapsed/Refractory Diffuse Large B-Cell Lymphoma (R/R DLBCL)

Based on the latest information I have collected, I will conduct a systematic and comprehensive analysis for you regarding the objective response rate (ORR) data and clinical endpoint achievement of Zenitar Biosciences’ Puyistat Mesylate (PM) as monotherapy for relapsed/refractory diffuse large B-cell lymphoma (R/R DLBCL):

According to academic literature reports, in the Phase I clinical trial,

[1]. This data demonstrates strong anti-tumor activity in the HDAC inhibitor field.

In the pivotal Phase IIa multicenter clinical trial,

among the full population, with an ORR of 50% in double-expressor lymphoma (DEL) patients[1]. Notably, one DEL patient maintained a response for over 23 months during an extended dosing period, demonstrating durable efficacy.

The Phase IIb clinical trial is being conducted at multiple centers nationwide to further verify the efficacy and safety of PM in a broader patient population[1].

• Mosunetuzumab monotherapy
  : Demonstrates promising efficacy in patients with R/R B-NHL
• Glofitamab combined with Polatuzumab Vedotin (Pola) regimen
  : ORR of 79.6% and CR rate of 51%
• Efficacy of Epcoritamab in DLBCL
  : ORR of 69% and CR rate of 39%

• Polatuzumab Vedotin (Pola) monotherapy
  : ORR of 56%
• Loncastuximab tesirine (Lonca) monotherapy
  : ORR of 48.3%
• Pola-BR combination regimen
  : ORR of 70%

[2]. This comparison demonstrates the competitive advantage of PM as a monotherapy, especially in the field of relapsed/refractory DLBCL where treatment options are limited.

• Phase IIa ORR of 69.0%
  : Significantly higher than historical control data (e.g., 48.3% for Lonca monotherapy)
• Prominent efficacy in the DEL patient subgroup
  : ORR of 50%, while DEL typically has a poor prognosis
• CR rate of 45.5%
  (Phase I data): A relatively high level among HDAC inhibitors
• Durable response
  : Some patients maintained a response for over 23 months

• Included in the conditional marketing review pathway by CDE
  : Indicates that the Center for Drug Evaluation (CDE) of the National Medical Products Administration (NMPA) recognizes the preliminary efficacy data of PM[2]
• Selected for ASCO poster presentation for two consecutive years
  : Gained attention and recognition from the international academic community

According to the general principles of drug clinical trials:

• Phase III clinical trials are the key stage for confirming efficacy
• Requires statistical support from a sufficient sample size (typically α=0.05, power ≥80%)
• Primary endpoints are usually ORR or progression-free survival (PFS), which require pre-specified statistical significance criteria

• Phase IIa data is exploratory/concept validation in nature
• Phase III clinical trial is ongoing
  (the first subjects in the experimental and control groups were enrolled in September 2025)
• Planned to complete conditional registration and submit a new drug application (NDA) in 2027

• Successful concept validation
  : Initially confirmed the efficacy of PM in R/R DLBCL
• Differentiated advantage
  : As a highly selective HDAC I/IIb inhibitor, its safety profile may be superior to pan-HDAC inhibitors
• Fills a treatment gap
  : Provides a new treatment option for patients with relapsed/refractory DLBCL

• Long-term survival benefits
  : Overall survival (OS) and progression-free survival (PFS) data need further verification in the Phase III trial
• Confirmatory efficacy
  : The results of the Phase III trial will provide the final statistical conclusion
• Safety profile
  : Safety data from a larger sample size

• The pivotal Phase III clinical trial
  is led by Professor Niu Ting from the Department of Hematology, West China Hospital of Sichuan University, and Professor Zhao Weili from Shanghai Ruijin Hospital
• Adopts a randomized controlled design
  (experimental group vs. control group)

• July 2025
  : Initiated the Phase III registrational clinical trial in China
• 2027
  : Complete conditional registration and submit a new drug application (NDA)
• 2028
  : Obtain conditional approval and achieve commercial launch

• Potential market size exceeds RMB 10 billion
• If approved, it will become
  the world’s first highly selective HDAC inhibitor for monotherapy of R/R DLBCL

Based on existing data,

(ORR of 69.0%), and the regulatory authority (CDE) has included it in the conditional marketing review pathway accordingly. However, in accordance with strict drug development standards, “achieving clinical endpoints” typically requires the results of a Phase III confirmatory clinical trial for final confirmation.

• Phase IIa data supports the continued advancement of the Phase III trial
• Efficacy data has advantages in competition within the same field
• Need to pay attention to the final results of the Phase III trial, especially PFS and OS data

• Uncertainty exists regarding the results of the Phase III trial
• Different safety signals may emerge with expanded sample size
• Changes in the market competition landscape may affect commercial prospects

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[1] Zenitar Biosciences Official Website - Puyistat Mesylate - Pivotal Phase III Clinical Study for Relapsed/Refractory Diffuse Large B-Cell Lymphoma (R/R DLBCL) (http://www.zenitar.com.cn/info.aspx?t=20&cid=208)

[2] Sina Finance - Tencent-backed Zenitar Biosciences Submits Listing Application to HKEX: Valuation Grew Nearly 4x in 5 Years with No Products on the Market Yet (https://finance.sina.com.cn/roll/2026-01-14/doc-inhhhnwp8305370.shtml)

[3] Academic Paper - Exploration of Treatment for Double-Expressor Diffuse Large B-Cell Lymphoma in the New Drug Era (https://lcxyen.whuhzzs.com/data/article/lcxy/preview/pdf/lcxyxzz-37-9-612.pdf)

[4] Chinese Experts’ Consensus on Antibody-Drug Conjugates for the Treatment of Hematologic Malignancies (2025 Edition) (https://www.zhongliujie.com/index.php/news/show/id/1097.shtml)