Response to sequential treatment with lymphoblastoid interferon-α in patients with Ph+ chronic myeloid leukemia unresponsive to recombinant interferon-α (rIFNα2a) and neutralizing-rIFNα2a antibodies negative

Nine Ph+ CML patients in chronic phase who were hematologically and/or karyotypically unresponsive to recombinant-IFNα2a (rIFNα2a) and neutralizing-rIFNα2a Abs negative were shifted from rIFNα2a to lymphoblastoid-IFNα (IFNα-Ly) therapy. After 3 months of IFNa-Ly treatment, the hematologic response was reinduced in 3 out of the 6 pts who were resistant to previous rIFNα2a therapy, and was maintained in 2 out of 3 patients who were hematologically but not karyotypically responsive to rIFNα2a. After 6 and 12 months, the hematologic response was progressively lost, being present only in 3 out of 7 and in 2 out of 3 evaluable patients respectively. None of the hematologically responsive patients achieved a karyotypic response (Ph neg. metaphases = 0%). One patient, who was hematologically responsive, continued being treated with IFNα-ly for 36 months but he did not achieve any karyotypic response. The results of this study suggest that in the unresponsive and neutralizing-rIFNα2a Abs negative CML patients a change in therapy, by using a non cross-reactive type of IFNα, would not be advantageous.