Recombinant interferon alpha-C for advanced hairy cell leukemia. An Israeli multicenter study

Malignancy: Current Clinical Practice: Treatment of Hairy Cell Leukemia at the Close of the 20th Century

In the last half of this century, hairy cell leukemia was recognized as a distinct B-cell malignancy, accounting for 2% of all leukemias. Characteristics include splenomegaly, pancytopenia, a usually indolent course, and responsiveness to both interferon and purine analog therapy. Accurate diagnosis requires the demonstration of malignant cells in the bone marrow and peripheral blood which contain cytoplasmic projections and characteristic surface antigens. Splenectomy was identified early as a palliative therapy, and in 1984 systemic treatment with interferon alpha was first reported to induce complete remissions. Soon thereafter, the purine analog deoxycoformycin was found to induce more durable complete remissions in a higher percentage of patients. In 1990, 2-Chlorodeoxyadenosine, a new purine analog therapy, was reported to be capable of inducing long-term durable responses in most patients after a single cycle. Current challenges include identifying which purine analog is the least toxic since both appear similarly effective, and neither appear to add to the already increased rate of second malignancies occurring in these patients. Moreover, up to 25% of patients with hairy cell leukemia fail initially or eventually to respond to standard therapy, making the development of new approaches necessary. The characteristic bright expression of several B-cell antigens on the malignant cells, including CD20, CD22 and CD25, has led to the development of targeted biotherapeutic approaches. A recombinant immunotoxin targeting CD25 has recently been reported to induce major responses and it is likely that other successful targeted approaches will be reported early in the new century.

Splenectomy vs. alpha interferon: a randomized study in patients with previously untreated hairy cell leukemia

Twenty patients with previously untreated hairy cell leukemia were randomized to undergo either splenectomy or to receive interferon alfa-N1, a highly purified natural alpha interferon, as primary therapy. A response in the peripheral blood elements to a hemoglobin greater than 110 gm/l, a granulocyte count greater than 1 x 10(9)/l, and a platelet count greater than 100 x 10(9)/l (Catovsky criteria) was noted in all ten patients receiving alpha interferon but in only three of the patients undergoing splenectomy (P = less than .01). Median time to response was longer in the ten interferon patients (153 days) than in the three splenectomy responders (20 days). Median time to treatment failure was significantly greater in the alpha interferon patients (greater than 18 months) than in the splenectomy patients (less than 1 month). Survival was no different since patients relapsing following splenectomy subsequently responded to alpha interferon. A significant decrease in leukemic bone marrow infiltration was observed in seven of ten patients receiving alpha interferon and in none of the patients undergoing splenectomy. Side effects, primarily infections, were more frequent in patients receiving interferon. Alpha interferon is preferable to splenectomy as initial treatment for hairy cell leukemia.

Interferon-beta induced remission in a hairy cell leukemia patient resistant to interferon-alpha

Two patients with advanced hairy cell leukemia and pancytopenia responded successfully to intramuscular injections of recombinant interferon-beta, with normalisation of blood counts. One of the patients had developed resistance to interferon-alpha. The in-vivo response was predicted by in-vitro studies showing a beneficial effect of IFN-beta on erythropoiesis in cell cultures derived from these patients.