Recombinant leukocyte A interferon in B-cell chronic lymphocytic leukemia: in vivo effects on autologous antitumor immunity.

Eight previously treated and four untreated patients with B cell chronic lymphocytic leukemia (CLL) received 20 X 10(6) U/m2 recombinant leukocyte interferon clone A (rIFN-alpha A) intramuscularly three times a week for 8 weeks. None of the eight patients who had received prior chemotherapy exhibited objective evidence of tumor regression. Two of the four previously untreated patients responded with transient (90%) decreases in absolute lymphocyte counts lasting for 2 and 7 months. Toxicity was moderate, with all patients experiencing a flu-like syndrome requiring a 50% dose reduction. Half of the patients exhibited anorexia, weight loss, and a drop in performance status. The two responders had normal serum immunoglobulin levels prior to treatment, whereas 80% of non-responders had depressed levels. Treatment with rIFN-alpha A was associated with a depression of nonspecific and specific humoral immunity in assays employing cryopreserved autologous pretherapy CLL cells. No consistent effects were demonstrable in cytolytic assays with purified peripheral blood T cells as effector cells, including one that utilized autologous CLL target cells. rIFN-alpha A has limited antitumor activity in B cell CLL which is restricted to untreated patients with an early stage of disease. With the assays employed it was not possible to demonstrate that rIFN-alpha A could augment autologous antitumor immunity.