Cyclacel
Research & Development

Sapacitabine (CYC682)

Both sapacitabine and CNDAC, its major metabolite, have demonstrated potent anti-tumor activity in preclinical studies. Sapacitabine is an orally-available prodrug of CNDAC, which is a novel nucleoside analog, or a compound with a structure similar to a nucleoside. A prodrug is a compound that has a therapeutic effect after it is metabolized within the body. CNDAC has a significantly longer residence time in the blood when it is produced in the body through metabolism of sapacitabine than when it is given directly.

Sapacitabine acts through a novel mechanism whereby the compound interferes with DNA synthesis through the incorporation of CNDAC into DNA during replication or repair, triggering a beta-elimination reaction and leading to the formation of single-strand DNA breaks, or SSBs. During subsequent rounds of replication, SSBs are converted to double-strand breaks, or DSBs; these can be repaired by the homologous recombination repair, or HRR, pathway, or, if unrepaired, result in cell death. Both sapacitabine and its major metabolite, CNDAC, have demonstrated potent anti-tumor activity in preclinical studies.

Sapacitabine has been evaluated in SEAMLESS, a Phase 3 study in acute myeloid leukemia, or AML, in the elderly, in an alternating schedule with decitabine. The study did not reach statistically significant superiority in overall survival (OS), although an improvement in complete remission rate was observed. In the stratified subgroup of patients with low baseline peripheral white blood cell count, comprising approximately two-thirds of the study's population, an improvement in OS was observed for the experimental arm. The Company is currently analyzing stratified and exploratory subgroups to identify patients who are most likely to benefit from treatment with the experimental arm. Depending on this analysis the Company may initiate discussions with European and U.S. regulators to determine a potential regulatory pathway.

Sapacitabine has been evaluated in both hematological cancers and solid tumors. Over 1,000 patients have received sapacitabine in Phase 1, 2 and 3 studies.

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Research & Development