Phase II study on combination therapy with CHOP-Zenapax for HTLV-I associated adult T-cell leukaemia/lymphoma (ATLL)

Adult T-cell leukaemia lymphoma (ATLL) is an aggressive T-cell malignancy caused by the human T-lymphotropic virus type-1 (HTLV-1) and is associated with a very poor prognosis. Combination chemotherapy has had little impact on the long term survival of these patients. ATLL cells are characterised by the expression of CD25 (IL-2R alpha), which is not expressed in normal resting T-cells. Daclizumab (Zenapax (R)) is a humanised murine anti-CD25 monoclonal antibody, which contains 10% murine CDR sequences. In this prospective trial 15 patients with aggressive ATLL were treated with CHOP-Zenapax (CHOP-Z) to determine the tolerability and feasibility of this novel regimen as well as evaluate its efficacy. Eleven patients had acute ATLL and four had the lymphoma subtype. The main presenting features were elevated LDH (100%), lymphocytosis (73%), lymphadenopathy (67%), skin lesions (40%), hypercalcaemia (53%), and hepato-splenomegaly (27%). Ten (67%) patients received the six scheduled cycles. Complete response (CR) lasting for two months or more was seen in 5 (33%), partial response in 3 (20%), minor response in 1 (7%), and no response in 6 (40%) patients. The median overall survival was 10 months (95% CI: 0.05-20.88) but this was significantly longer among responders (18 months) compared to non responders (3 months) (P = 0.019). For patients who achieved CR the disease free survival (DFS) was 15 months while the event-free survival (EFS) was 5 months. In conclusion CHOP-Z is safe and in those who achieve a complete response it was associated with prolonged overall survival.