On August 6, 2025 Dizal (SSE:688192), a biopharmaceutical company committed to developing novel medicines for the treatment of cancer and immunological diseases, reported that the U.S. Food and Drug Administration (FDA) has granted Fast Track Designation to its Birelentinib (DZD8586) for the treatment of adult patients with relapsed/refractory chronic lymphocytic leukemia or small lymphocytic lymphoma (CLL/SLL) who have received at least two prior lines of therapy, including a BTK inhibitor and a BCL-2 inhibitor (Press release, Dizal Pharma, AUG 6, 2025, View Source [SID1234654887]).
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Patients with CLL/SLL treated with a BTK inhibitor or a BCL-2 inhibitor often relapse or progress due to two major resistance mechanisms: BTK C481X mutations and BTK-independent activation of BCR signaling pathway. No targeted therapy currently addresses both mechanisms, posing an urgent clinical challenge. Although BTK degraders have shown encouraging anti-tumor activity in early CLL/SLL clinical studies, mutation-mediated resistance has already been reported, and degrader-associated toxicities may limit their long-term clinical application.
Birelentinib is a first-in-class, non-covalent, LYN/BTK dual inhibitor with full blood-brain barrier (BBB) penetration. It has high selectivity against other TEC family kinases (TEC, ITK, TXK and BMX). By targeting both BTK and LYN, it blocks both BTK-dependent and -independent BCR-signaling pathways, effectively inhibiting tumor growth of B-cell non-Hodgkin lymphomas (B-NHLs).
The Fast Track Designation is supported by data from a pooled analysis of two phase I/II studies of birelentinib in CLL/SLL patients previously treated with covalent/non-covalent BTK inhibitors and BTK degraders. The results were presented at 2025 European Hematology Association (EHA) (Free EHA Whitepaper) Annual Congress and featured in oral presentations at both the 2025 American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting and the 18th International Conference on Malignant Lymphoma (ICML).
Birelentinib demonstrated significant anti-tumor efficacy in heavily pretreated CLL/SLL patients with an objective response rate (ORR) of 84.2%, with a good safety profile. Tumor responses were observed irrespective of prior treatment with covalent/non-covalent BTK inhibitors, BTK degraders, or BCL-2 inhibitors, including in patients harboring classic BTK resistance mutations (C481X) as well as other BTK mutations, such as kinase-dead mutations. Responses were durable, with an estimated 9-month duration of response (DOR) rate of 83.3%.
"The granting of Fast Track Designation underscores the U.S. FDA’s recognition of birelentinib’s potential to address an unmet medical need in patients with CLL/SLL," said Dr. Xiaolin Zhang, CEO of Dizal. "We look forward to working closely with the FDA to accelerate the global clinical development of birelentinib and bring this treatment option to patients as quickly as possible."
Fast Track Designation is an FDA program designed to facilitate the development and expedite the review of drugs for serious conditions that address unmet medical needs. The designation enables for frequent FDA interactions and may allow for rolling revie, priority review, or accelerated approval if criteria are met.
About Birelentinib (DZD8586)
Birelentinib is a first-in-class, non-covalent, LYN/BTK dual inhibitor with full blood-brain barrier (BBB) penetration, designed as a potential treatment option for B-cell non-Hodgkin lymphoma (B-NHL).
While Bruton’s Tyrosine Kinase (BTK) inhibitors have been approved for the treatment of B-NHL, resistance can arise through two major mechanisms: the BTK C481X mutation and BTK-independent BCR signaling pathway activation. Currently, there is no targeted therapy available to address both resistance mechanisms, posing an urgent clinical challenge. Although BTK degraders have shown encouraging efficacy in early clinical studies, mutation-related resistance has been reported, and degrader-related toxicities may affect long-term clinical application.
Birelentinib has high selectivity against other TEC family kinases (TEC, ITK, TXK and BMX). By targeting BTK and LYN, it blocks both BTK-dependent and -independent BCR-signaling pathways, effectively inhibiting tumor growth of B-NHLs in cell lines and in animal models. In clinical studies, birelentinib exhibits favorable PK properties, good central nervous system (CNS) permeability, complete blockade of BCR signaling, and encouraging anti-tumor efficacy with good safety and tolerability in patients with B-NHL.
In August 2025, birelentinib was granted Fast Track Designation by the U.S. FDA for the treatment of adult patients with relapsed/refractory chronic lymphocytic leukemia or small lymphocytic lymphoma (CLL/SLL) who have received at least two prior lines of therapy, including a BTK inhibitor and a BCL-2 inhibitor.