Treating acute myeloid leukemia with VALOR – vosaroxin in combination with cytarabine

Farhad Ravandi, MD from the University of Texas MD Anderson Cancer Center, Houston, TX, explains results from the VALOR trial of vosaroxin in refractory and relapsed acute myeloid leukemia (AML) at the American Society of Hematology (ASH) Congress 2016 in San Diego, CA. He explains that treatment outcomes for relapsed and primary refractory AML are generally poor. Despite the large amount of progress made in understanding the biology of leukemogenesis, there have been no new drug approvals for AML as a whole. He is hopefully that this will change in the near future with positive trials of compounds which are awaiting regulatory approval. In the overall AML population, there is still a high dependency on cytotoxic chemotherapy for treating patients, and even when the new compounds are approved and available these are likely to be combined with traditional chemotherapy. Vosaroxin, a general anti-cancer quinolone derivative with topoisomerase II inhibition activity, is of great interest in leukemia treatment. In addition, it has limited non-bone marrow-related toxicity as it produces less reactive oxygen species (ROS) and is therefore less cardiotoxic. Particularly in relapsed AML, where patients have already received anthracycline-based induction and consolidation therapy, this may be a good option. Prof. Ravandi discusses data from the Phase III VALOR trial (NCT01191801), which aimed to investigate whether the addition of vosaroxin to higher dosed cytarabine (Ara C) is superior to cytarabine alone in primary refractory or first relapse AML. Cytarabine was chosen as this is the best currently available anti-AML agent. 711 patients were stratified based on age and duration of first remission, and were randomized to receive cytarabine together with vosaroxin or placebo. Primary analysis was reported at ASH 2014, with unstratified analysis showing that overall survival (OS) was not superior in the vosaroxin-treated group, while stratified analysis showed an advantage, which was confined to the older patient population over 60 years of age. These patients showed an improvement in response and survival when treated with vosaroxin compared to placebo. He highlights that follow-up data have now been presented at ASH 2016, with results showing that specifically in the older age group the advantage of vosaroxin is stable over time, with improved overall survival (OS) seen in this group. Additionally, the early treatment toxicity at 60 and 90 days is comparable between vosaroxin and placebo treated patients, despite the fact that vosaroxin is cytotoxic.

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