Phase 2 study of the efficacy and safety of the combination of arsenic trioxide, interferon alpha, and zidovudine in newly diagnosed chronic adult T-cell leukemia/lymphoma (ATL).

Adult T-cell leukemia/lymphoma (ATL) is resistant to chemotherapy and carries a dismal prognosis particularly for the acute and lymphoma subtypes. Promising results were obtained with the combination of zidovudine and interferon-alpha. Chronic ATL has a relatively better outcome, but poor long-term survival is noted when patients are managed with a watchful-waiting policy or with chemotherapy. In ATL cell lines, arsenic trioxide shuts off constitutive NF-kappaB activation and potentiates interferon-alpha apoptotic effects through proteasomal degradation of Tax. Clinically, arsenic/interferon therapy exhibits some efficacy in refractory aggressive ATL patients. These results prompted us to investigate the efficacy and safety of the combination of arsenic, interferon-alpha, and zidovudine in 10 newly diagnosed chronic ATL patients. An impressive 100% response rate was observed including 7 complete remissions, 2 complete remissions but with more than 5% circulating atypical lymphocytes, and 1 partial response. Responses were rapid and no relapse was noted. Side effects were moderate and mostly hematologic. In conclusion, treatment of chronic ATL with arsenic, interferon-alpha, and zidovudine is feasible and exhibits an impressive response rate with moderate toxicity. Long-term follow up will clarify whether this will translate to disease cure. Overall, these clinical results strengthen the concept of oncogene-targeted cancer therapy.