Biosight Reports Final Primary Endpoint Data from Phase 2b Study of Aspacytarabine (BST-236) for First-Line Acute Myeloid Leukemia Therapy

Complete remission rate of 37%, of which 50% were minimal residual disease negative

Single-agent activity and favorable safety demonstrated in most challenging AML patient populations

Study results presented at the 2021 ASH Annual Meeting

AIRPORT CITY, Israel, Jan. 06, 2022 (GLOBE NEWSWIRE) --  Biosight Ltd., a pharmaceutical development company developing innovative therapeutics for hematological malignancies and disorders, today announced final results for the primary study endpoint, complete remission (CR), from the Company’s Phase 2b clinical trial evaluating single-agent aspacytarabine (BST-236) as a first-line acute myeloid leukemia (AML) therapy for patients unfit for standard induction chemotherapy. These results, presented at the 2021 American Society of Hematology (ASH) Annual Meeting held in December, 2021, demonstrated efficacy, safety, and tolerability of BST-236 as a monotherapy in treatment of newly-diagnosed AML patients unfit for standard induction therapy.

“These final complete remission data are extremely encouraging and strengthen our conviction in the potential of aspacytarabine as a potential standard-of-care treatment option for AML patients,” said Jessica Altman M.D., Professor, Medicine, Hematology Oncology Division, Feinberg School of Medicine, Robert H. Lurie Comprehensive Cancer Center of Northwestern University and Lead Study Investigator. “Notably, a complete remission rate of 37% was achieved in a challenging patient population, including patients with secondary AML, prior hypomethylating agent treatment, and older age. While follow-up is still ongoing, the efficacy data across key measures, including duration of response and overall survival, combined with a favorable safety profile and a time-limited treatment of up to 4 courses, all form the basis for my confidence in aspacytarabine as a novel therapy for the treatment of patients with AML.”

Key highlights from the poster presentation titled, “Aspacytarabine (BST-236) as Monotherapy is Safe, Well-tolerated and Effective for the Treatment of Adults with Newly Diagnosed Acute Myeloid Leukemia Unfit for Intensive Therapy. Results of a Phase 2 Study (NCT03435848) presented by Dr. Altman include:

  • As of the data cutoff date of December, 2021, 65 AML patients from the Phase 2b study were evaluable for safety and efficacy analysis
  • All patients were unfit for standard induction chemotherapy; baseline patient characteristics include a median age of 75 years, 38% of patients (n=25) with ECOG PS 2, 40% of patients (n=26) with secondary AML, 17% with prior hypomethylating agents (HMAs) ± venetoclax treatment (n=11) and 52% (n=34) with adverse European LeukemiaNet (ELN) scores
  • Patients were treated with up to four 6-day courses of aspacytarabine at a dose of 4.5 g/m2/d; aspacytarabine was well-tolerated, CR rates were 37% across all evaluable patients (n=65), 27% in patients with prior HMA ± venetoclax therapy (n=11), 44% in de novo AML patients (n=39), 27% in secondary AML patients (n=26), 35% in patients ≥ 75 years old (n=34), and 32% in patients with adverse ELN risk scores (n=34)
  • Rapid complete hematological recovery was observed in all patients who achieved a complete bone marrow response, with a median time of 25 days (range 11-39) for complete neutrophil recovery and 26 days (range 18-40) for complete platelet recovery
  • 50% of evaluable CRs were minimal residual disease negative (MRD(-))
  • Median duration of response (DOR) and median overall survival (OS) follow up is ongoing

Ruth Ben Yakar, Ph.D., Chief Executive Officer of Biosight, said, “We continue to be very encouraged by the promising results of this larger data set, reinforcing our belief that aspacytarabine has the potential to become standard of care in patients with AML and may address a significant unmet need for those unfit for intensive chemotherapy. These results strongly support the continued progression of our aspacytarabine clinical trial program, with the recently announced expansion into additional Phase 2 studies in patients with relapsed or refractory AML and myelodysplastic syndrome (MDS).”  

About Aspacytarabine (BST-236)

Aspacytarabine is a novel proprietary anti-metabolite. It is composed of cytarabine covalently bound to asparagine, acting as a prodrug of cytarabine. Cytarabine has served as the backbone of AML therapy for over 45 years due to its superior efficacy; however, it is associated with severe bone marrow, gastrointestinal, and neurological toxicities, which significantly limit its use, especially in older and medically compromised patients. Due to its unique pharmacokinetics and metabolism, aspacytarabine enables high-dose therapy with lower systemic exposure to free cytarabine and relative sparing of normal tissues. As such, aspacytarabine may serve as a superior therapy for AML and other hematological malignancies and disorders, including for older adults who are unfit to receive intensive therapy.

Aspacytarabine was granted FDA Fast Track Designation for the first-line treatment of AML patients unfit for standard chemotherapy, and Orphan Drug Designations by the FDA and EMA, which entitle Biosight to 7 and 10 years of market exclusivity in the US and Europe, respectively, upon marketing approval of aspacytarabine for the treatment of AML in each territory.

Final primary endpoint analysis from a Phase 2b study recently completed enrollment, evaluating single-agent aspacytarabine as a first-line AML therapy have demonstrated safety and single-agent activity, and additional studies are ongoing to evaluate aspacytarabine as a second-line treatment for patients with relapsed or refractory MDS or AML. For more information regarding the Phase 2b clinical study of BST-236, please visit

About Biosight Ltd.

Biosight is a private Phase 2 clinical stage biotech company developing innovative therapeutics for hematological malignancies and disorders. Biosight’s lead product, aspacytarabine (BST-236), is an innovative proprietary anti-metabolite which addresses unmet medical needs by enabling high-dose chemotherapy with reduced systemic toxicity. Aspacytarabine is currently being investigated as a single agent in a Phase 2b clinical trial, which recently completed enrollment and primary endpoint analysis, for the first-line treatment of AML. Results demonstrate tolerability with promising efficacy in the challenging population of AML patients unfit for intensive standard-of-care chemotherapy. Additional Phase 2 studies are ongoing in patients with relapsed/refractory AML and MDS, including a study in collaboration with the European cooperative group, Groupe Francophone des Myélodysplasies (GFM). For additional information, please visit

Chuck Padala
LifeSci Advisors, LLC