Phase I Study Results for Pegylated Megakaryocyte Growth And Development Factor, A New Platelet Growth Factor
Results of the first trial of pegylated megakaryocyte growth and development factor (PEG_rHuMGDF), a novel platelet growth factor, in human beings were presented at the ASCO Annual Meeting by Michael Fanucchi, M.D., associate professor of medicine, Winship Cancer Center, Emory University (Atlanta, GA).
Decreased platelet production, which can be cause by chemotherapeutic agents, is a serious problem for cancer patients. Low platelet counts can leave a patient at risk for excessive bruising, internal bleeding, and even intracerebral hemorrhaging. Previous studies of PEG-rHuMGDF in animals have shown that the compound is effective in restoring platelet levels to normal. The substance that drives platelet production, thrombopoietin, was identified only recently. PEG-rHuMGDF, a recombinant form, was developped for therapeutic use in larger quantities than is normally produced in the body.
Fifty patients with lung cancer Stage III (extensive tumors within the chest cavity) or IV (tumors that have spread outside the chest cavity) who had not been treated previously with chemotherapy were randomized to treatment with carboplatin and paclitaxel with or without PEG-rHuMGDF.
The most significant results were the rapid return to baseline platelet count and the higher platelet nadir (lowest count) for patients in the MGDF-treated groups. After chemotherapy, the median return time to baseline platelet count in the MGDF-treated patients was 13 days; the platelet count of the placebo group did not recover to baseline before the next cycle of chemotherapy. Also, post-chemotherapy the median platelet nadir for all the MGDF patients was 189,000 per cubic millimeter of blood (cmm), which was 70% higher than the placebo group whose platelet count dropped to 111,000/cmm. Pre-chemotherapy platelet counts of both groups were the same. Normal platelet counts range between 150,000/cmm and 450,000/cmm.
"The ability to replenish platelets is a big step forward in the treatment of cancer," Lynn Mara Schuchter, M.D., assistant professor of medicine, University of Pennsylvania Cancer Center (Philadelphia, PA), said at a press briefing today. "Additional studies are required to confirm these promising early data."