A Pilot Phase II Study of the Feasibility and Efficacy of Vincristine Sulfate Liposome Injection in Patients With Relapsed or Refractory Acute Myeloid Leukemia

BACKGROUND: Resistance to therapy and a poor outcome characterize relapsed or refractory acute myeloid leukemia (AML). There is a clear need for additional palliative approaches with acceptable toxicities. Vincristine sulfate liposome injection (VSLI) confers enhanced pharmacokinetics and activity when compared to the parent compound. It is effective and well tolerated in heavily pretreated acute lymphoblastic leukemia (ALL) patients. Preclinically VSLI has activity in vincristine-resistant cancers. As relapsed or refractory AML patients would have minimal exposure to vincristine it was hypothesized that VSLI would be well tolerated and may have activity. METHODS: A pilot phase II clinical trial was conducted. Five patients with relapsed or refractory disease were treated using the Food and Drug Administration (FDA)-approved dose and schedule. RESULTS: Of the five patients treated none completed more than one cycle; there were no responses and two patients did not complete one cycle of therapy. Surprisingly, three of the five patients had treatment-related constipation, and two had neuropathy consistent with the known toxicities of VSLI. Given the toxicity and lack of response, the trial was terminated early. CONCLUSIONS: VSLI had no activity against relapsed or refractory AML in this limited, single institution dataset.