Pilot Study of Low Dose Melphalan and Bortezomib for Treatment of Acute Myelogenous Leukemia and High-Risk Myelodysplastic Syndromes.

Elderly patients with AML (>60) have a poor prognosis due to high risk cytogenetics and a high incidence of secondary AML. Comorbid conditions make induction therapy more risky and less effective. There is a need for less toxic and more effective treatment for these patients. The combination of bortezomib (B) and melphalan (M) demonstrate synergistic cytotoxicity in vitro against AML cell lines providing a rationale for this combination in patients with AML. We report the initial results of a pilot study of low-dose M and B for the treatment of patients with AML and high-risk myelodysplastic syndromes. Eligibility requirements included a diagnosis of AML or high-risk MDS and subjects were not candidates for standard induction therapy or had failed therapy. Strata 1 included patients who had received no previous therapy and strata 2 patients with refractory or relapsed disease. Treatment consisted of M (2mg) oral daily dose and B (1.0mg/M2) on day 1, 4, 8 &11 of a 28 day cycle. Ten patients have been enrolled. Median age was 69 (range 54–79), 8 patients w/ AML and 2 w/ refractory MDS. Five patients were previously treated (strata 2); regimens included induction (7(3), auto SCT (1) and azacytadine (2). Cytogenetic abnormalities were present in 70% of patient specimens. To date 25 cycles of treatment have been given (range 1–6). Six patients are evaluable for response. Two patients (both with MDS) were withdrawn after 1 cycle for cytopenias. Two patients with AML achieved CR by bone marrow morphology. One patient, a 78 year old man with multiple cytogenetic abnormalities and no previous treatment achieved remission with normalization of cytogentetics after 4 cycles. A 74 year old man who had failed previous therapy for his AML achieved a morphologic remission with persistent cytogenetic abnormalities after 6 cycles. Three patients required admission for management of febrile episodes in association with neutropenia that were disease related. There were no treatment related admissions or grade 3/4 non hematologic toxicity events. The 74 year old man who achieved a CR with no “in hospital” days while on study had previously failed to respond to two induction attempts which required a 44 day hospitalization. Accrual continues. In summary, the combination of low dose oral melphalan with low dose bortezomib appears to be a novel, active and well tolerated outpatient treatment for elderly patients with high risk MDS and AML.