Acute myeloid leukemia (AML) is associated with poor outcome in older patients and in patients unfit for standard induction therapy. Cytarabine serves as the backbone of treatment for AML for decades, however, standard cytarabine therapy is associated with severe side effects, such as cerebellar toxicity, bone marrow suppression, and infections, leading to high treatment-related mortality rates.
Hence, while the incidence of AML increases with age, advanced age and comorbidities may preclude the administration of intensive induction therapy altogether due to its potential toxicities. The outcome in older patients who are unable to receive intensive chemotherapy remains poor, in spite of recent approvals of new therapeutics.
BST-236 (INN aspacytarabine) is a novel proprietary anti-metabolite. It is composed of cytarabine covalently bound to asparagine, acting as a pro-drug of cytarabine, enabling delivery of high cytarabine doses to leukemia cells with lower systemic exposure to the free drug. Inside the leukemia blasts, BST-236 is cleaved to cytarabine, enabling effective killing of target cells and relative sparing of normal tissues. As such, BST-236 may serve as an ideal therapy for leukemia, particularly for delivering high doses of cytarabine to medically unfit or older adults who otherwise cannot be treated by effective doses of chemotherapy.
Results from a recently completed Phase 1/2a study, presented at the 59th Annual American Society of Hematology meeting in Atlanta, GA, USA, demonstrate that BST-236 treatment of acute leukemia patients is safe and well tolerated, enabling delivery of high doses of cytarabine to older and unfit patients, leading to high response rates and prolonged survival.
A multi-center Phase 2b trial in the US and Israel was recently launched and is currently enrolling newly-diagnosed AML patients who are unfit for standard chemotherapy.
Additional clinical studies in various hematological indications are planned to be initiated in the coming months.