Clinical efficacy of all-trans retinoic acid for treating adult T cell leukemia

We previously reported that all-trans retinoic acid (ATRA) inhibited growth in human T-cell leukemia virus type I (HTLV-I)-positive T-cell lines and in fresh cells from patients with adult T cell leukemia (ATL). Here, we confirmed the clinical effects of ATRA in 20 patients with ATL. The 20 patients (n = 20) with a median age of 56 (range 35–73) years who were diagnosed with ATL received ATRA orally. The efficacy of treatment was as follows: no complete response (CR), a partial response (PR) in 40% of the patients, no change (NC) in 45% of the patients, and a progressive disease (PD) in 15% of the patients. In seven acute-type ATL patients, a PR was achieved in two (28.5%), NC was observed in two (28.5%), and a PD was observed in three (42.8%). In three lymphoma-type ATL patients, a PR (100%) was achieved. Among four chronic-type ATL patients, a PR was achieved in one (25%) and NC was observed in the remaining three (75%). In six smoldering-type ATL patients, a PR was achieved in two (33.3%) and NC was observed in four (66.6%). The major side effects were headache (n = 5), transient liver dysfunction (n = 2), hyperlipidemia (n = 2), and anorexia (n = 1). These results indicated that ATRA might be a useful agent for the safe treatment of ATL.