Therapeutic effects of low‐dose cytosine arabinoside, alpha‐interferon, 1α‐hydroxyvitamin D3 and retinoic acid in acute leukemia and myelodysplastic syndromes

62 evaluable patients with myelodysplastic syndromes (MDS) or acute leukemia were treated with different combinations of low dose ara-C, alpha-interferon (IFN), 1 alpha-hydroxyvitamin D3 (vit D3) and retinoic acid. The aim was to study the efficacy and toxicity of each combination. The overall rate was 44%. Of these, 50% responded favorably to the combination of IFN, vit D3 and retinoic acid (IDR), which was comparable to the response rate of 43% for low-dose ara-C. The results of the IDR treatment may be explained by additive or synergistic effects between the separate drugs in the combination. Ara-C and IDR treatment was generally well-tolerated but interferon gave more side effects than any other drug used in the study. Evaluation of the full combination of ara-C, IFN, vit D3 and retinoic acid was not possible because of toxicity. Marrow hypoplasia was infrequent (5/27 patients) in cases responding favorably to treatment. Complete remissions were not longer than partial remissions or significant responses.