Clinical Advantage Analysis of Purinostat Mesylate in T-Cell Lymphoma

Based on the collected professional information, I will provide you with a comprehensive analysis report on the clinical advantages of Zenitar Biotech’s HDAC inhibitor in T-cell lymphoma.

Purinostat Mesylate (PM), a next-generation

[0], is independently developed by Chengdu Zenitar Biotech. This drug has the following unique advantages:

1. Uniqueness Advantage
   : It is currently the
   only HDAC inhibitor approved by regulatory authorities for the treatment of B-cell lymphoma, T-cell lymphoma, and solid tumors simultaneously
   [0], a feature that enables broader indication coverage in clinical applications.

2. Innovative Structural Design
   : It features an innovative
   non-linear large triangular cap structure
   , which greatly enhances the binding affinity with HDAC I/IIb[0].

Purinostat Mesylate has dual advantages in its mechanism of action[0]:

1. Precise Epigenetic Regulation
   : Achieves precise anti-tumor effects by inhibiting key genes and signaling pathways associated with tumor cell survival
2. Immune Activation Effect
   : Can activate the immune system and induce immune memory, thereby achieving a synergistic anti-tumor effect
3. Resistance Overcoming
   : Exhibits excellent anti-tumor activity in various DLBCL cell lines and PDX models, and can overcome drug resistance to multiple targeted therapies

Compared with approved HDAC inhibitors, Purinostat Mesylate has a significant selectivity advantage[0]:

1. Highly Selective Inhibition
   : Molecular design focuses on selectivity and safety, avoiding cardiovascular toxicity and immunosuppression-related adverse reactions common in broad-spectrum HDAC inhibitors

2. Reduced Toxicity Risk
   :
   • The role of HDAC Class IIa and IV in tumorigenesis remains controversial
   • A growing body of evidence shows that inhibiting HDAC Class IIa and IV may trigger more cardiovascular toxicity and immunosuppression-related adverse reactions
   • Purinostat Mesylate effectively reduces the above risks by precisely inhibiting HDAC Class I and IIb

1. Phase IIa Clinical Study
   :
   • A Phase IIa clinical study for the treatment of relapsed/refractory peripheral T-cell lymphoma (PTCL) and cutaneous T-cell lymphoma (CTCL) was initiated in April 2024[1]
   • Led by Professor Zhao Weili from Ruijin Hospital, Shanghai, and Professor Niu Ting from the Department of Hematology, West China Hospital, Sichuan University[1]
   • Phase I clinical study has demonstrated
     favorable efficacy and safety
     in this patient population[1]

2. Efficacy Reference from B-Cell Lymphoma
   :
   • In the Phase IIa study of relapsed/refractory diffuse large B-cell lymphoma (R/R DLBCL), the
     objective response rate (ORR) reached 69.0%
     [0]
   • The complete response (CR) rate reached 45.5%[0]
   • This efficacy is
     non-inferior or superior to the combined treatment effect of bispecific antibodies and ADC drugs
     (ORR of approximately 50%-65%)[0]

Drug	ORR	CR Rate	Remarks
Purinostat Mesylate	69.0%	45.5%	Highly selective Class I/IIb inhibitor
Chidamide	27.8%	13.9%	Class I selective inhibitor
Romidepsin	29.3%	14.6%	Broad-spectrum HDAC inhibitor
Belinostat	25.8%	10.8%	Broad-spectrum HDAC inhibitor

1. Regulatory Recognition
   :
   • The product has successfully entered pivotal Phase III clinical trials[0]
   • Has been
     included in the conditional marketing review pathway
     by the Center for Drug Evaluation (CDE) of the National Medical Products Administration (NMPA)[0]
   • Selected for ASCO poster presentation for two consecutive years[0]

2. Market Potential
   :
   • The Phase III clinical study plans to complete conditional registration and file for marketing in 2027[0]
   • Expected to become the
     world’s first highly selective HDAC inhibitor for single-agent treatment of r/r DLBCL
     [0]
   • The corresponding potential market exceeds RMB 10 billion[0]

3. Global Layout
   :
   • Obtained FDA clinical trial approval in May 2025[0]
   • Accelerates global strategic layout

Zenitar Biotech is a

dedicated to integrating structural biology, artificial intelligence, and clinical-related disease models to develop highly differentiated small-molecule therapies with first-in-class or best-in-class potential[0].

The company’s pipeline includes[0]:

• Two core products
  : Flunitinib Maleate and Purinostat Mesylate for injection
• Two clinical-stage drug candidates
  : ZL-82 and ZL-85
• Four preclinical-stage drug candidates
  : ZL-65, ZL-69, ZL-59, and ZL-89

Purinostat Mesylate demonstrates the following core clinical advantages in the treatment of T-cell lymphoma:

1. Significant Efficacy
   : Phase IIa study shows favorable anti-tumor activity
2. Superior Safety
   : High-selectivity design reduces the toxicity risks of traditional HDAC inhibitors
3. Unique Mechanism
   : Dual mechanism of action (epigenetic regulation + immune activation) achieves synergistic anti-tumor effect
4. Broad Indications
   : The only HDAC inhibitor covering B-cell lymphoma, T-cell lymphoma, and solid tumors simultaneously
5. Promising Prospects
   : Included in the conditional marketing review pathway, with expected commercialization in 2027

With the advancement of clinical trials, Purinostat Mesylate is expected to provide a new treatment option for patients with relapsed/refractory T-cell lymphoma.

[0] Zenitar Biotech Official Website - Clinical Research Progress of Purinostat Mesylate (http://www.zenitar.com.cn/info.aspx?t=20&cid=208)

[1] Zenitar Biotech Official Website - First Patient Enrolled in Phase IIa Clinical Study of Relapsed/Refractory T-Cell Lymphoma (http://www.zenitar.com.cn/info.aspx?cid=142&t=19)