Low-dose Oral Clofarabine for the Treatment of IPSS INT-1, INT-2 or HIGH Myelodysplastic Syndromes and Chronic Myelomonocytic Leukemia

Study Summary

Study and Dose Rationale The safety profile of clofarabine appears acceptable within the target populations studied to date in the clinical studies summarized in Section 2.3. clofarabine has demonstrated anti-cancer activity through inhibition of DNA synthesis and repair, induction of apoptosis, and possibly through other mechanisms. The effect of clofarabine on DNA methylation has not been determined. Numerous responses have been observed after treatment with clofarabine in heavily pre-treated relapsed/refractory patients with ALL or AML. Recently 2 small studies were conducted at the M.D. Anderson Cancer Center looking at the use of clofarabine in the treatment of MDS.31 The first study randomized patients in a Bayesian fashion to 15 vs. 30 mg/m2 given IV daily for 5 days every 4 to 8 weeks. In the 15 mg/m2 arm 3 of 7 patients had a complete remission according to the International Working Group (IWG)32 criteria for response. In the 30 mg/m2 arm, 2 of 6 patients had a complete remission while 1 patient had hematologic improvement according to IWG criteria. In the second study, patients were treated with oral clofarabine at a dose of 40 mg/m2 daily for 5 days every 4 to 8 weeks. Two of 7 patients had hematologic improvement according to IWG criteria. The main toxicities in both trials were prolonged myelosuppression and liver function abnormalities. Preclinical animal models have shown increased clofarabine activity against multiple different tumors with repetitive daily dosing for prolonged periods of time.33 The use of an oral therapy is advantageous for the treatment of a chronic malignancy such as MDS. Furthermore, based on the pre-clinical data mentioned above daily repetitive dosing over a protracted period may provide increased efficacy. Since most MDS patients are elderly and may not tolerate aggressive therapy, a schedule of administration of low dose oral clofarabine over a protracted period may provide the advantage of increased efficacy without severe

Interventions

• DRUG Clofarabine