A combination trial of human lymphoblastoid interferon and bestrabucil (KM2210) for adult T‐cell leukemia–lymphoma

Both human lymphoblastoid interferon (HLBI) and bestrabucil, the conjugate of chlorambucil and β‐estradiol, have antitumor activity against adult T‐cell leukemia‐lymphoma (ATLL). Because an in vitro study showed that these two agents combined had a synergistic antiproliferative effect on MOLT‐4 and WI‐38VA13 cell lines, the authors evaluated the clinical efficacy of this combination in a pilot study with a poor‐risk group of ATLL patients. The patients were treated daily with 6 × 106 IU of HLBI subcutaneously and 100 mg of bestrabucil orally. In patients with lymphoma‐type ATLL or hypercalcemia, prednisolone also was given daily. Of 12 patients suitable for evaluation, nine had partial responses, one had a minor response, and two had no response. All five patients with skin infiltration and both patients with hypercalcemia responded. A history of prior chemotherapy did not affect the response rate. The time to clinical response was 3 to 16 days (median, 11 days) after initiation of treatment. The response duration was 4 to 108+ weeks (median, 9 weeks), but all patients except one relapsed, even during continuing treatment. No serious side effects were observed. Although the response rate with this combination treatment was high, the response duration was short, and other treatments would have to be added to achieve control of this aggressive disease.