Phase I Study Results for Thrombopoietin, A New Cytokine
Saroj Vadhan-Raj, M.D., associate professor and director, Regulation of Hematopoiesis, Bioimmunotherapy Department, M.D. Anderson Cancer Center (Houston, Texas), presented interim results of two Phase I studies of single-dose recombinant human thrombopoietin (rhTPO) therapy given to patients receiving chemotherapy.
Patients who undergo intensive chemotherapy and radiation may experience thrombocytopenia, a sharp reduction in platelets, which can lead to bleeding complications. Researchers have been studying whether rhTPO can stimulate more rapid production of platelets following anticancer treatment. Interim results from two Phase I clinical studies indicate that rhTPO appears safe and well tolerated and that higher doses of the drug result in increased platelet production. This may be helpful in treating cancer patients so they can avoid the side effects of chmotherapy and radiation, and possibly tolerate higher doses of anticancer treatment.
According to Dr. Vadhan-Raj, single doses of rhTPO were administered to 14 cancer patients receiving chemotherapy. Both studies began with "Cycle 0," a 21-day pre-chemotherapy period, to determine the safety of rhTPO and platelet production levels in response to three different single doses of rhTPO. Patients then receive the same dose of rhTPO after chemotherapy in subsequent cycles.
Fourteen patients had been treated upon submission of Dr. Vadhan-Raj's abstract. In Cycle 0, the lowest dose of rhTPO was minimally active, but increased platelet production occurred at higher doses. At the highest dose level tested (1.2 mcg/kg), the median platelet count increase was 158%.
"Thrombocytopenia is a serious problem for patients undergoing chemotherapy which predisposes patients to serious bleeding complications. Until now, we have not had optimal treatment," Lynn Mara Schuchter, M.D., assistant professor of medicine, University of Pennsylvania Cancer Center (Philadelphia, PA), said at a press briefing today. "These preliminary results with rhTPO are encouraging, but further investigation will be needed to confirm both its efficacy and safety.