ASCO--Both forms of recombinant human platelet growth factor currently
under study have been shown to enhance platelet recovery after
myelosup-pressive chemotherapy without serious side effects. The
first four clinical trials of the two products--pegylated megakaryocyte
growth and development factor (MGDF, Amgen), which is linked to
polyethylene glycol to improve its stability and half-life; and
thrombopoietin (rhTPO, Genentech)--were presented at an ASCO scientific
Two randomized, double-blind, placebo-controlled phase I/II trials,
one in the United States and one in Australia, showed the safety
and efficacy of MGDF. In the US trial, conducted at Emory, UCLA,
and Duke, MGDF (at six dose levels ranging from .03 to 5 mcg/kg/day)
proved safe and well tolerated when given after carboplatin (Paraplatin)
and paclitaxel (Taxol) therapy. The 53 patients had previously
untreated stage III or IV non-small-cell lung cancer.
Administration of multiple injections of MGDF after chemotherapy
resulted in significantly faster recovery of platelet counts (median,
14 days vs more than 21 days with placebo), said Michael Fanucchi,
MD, associate professor of medicine, Emory University.
Post-chemotherapy platelet nadirs also were 70% higher in patients
treated with MGDF than in those given placebo (median, 189,000
In the Australian trial, patients with previously treated advanced
cancers were given placebo or MGDF together with G-CSF (Neupogen)
either before (17 patients) or after (41 patients) therapy with
carboplatin plus cyclophosphamide.
MGDF enhanced platelet recovery in a dose-dependent manner, said
Dr. G. Begley, of the Centre for Developmental Cancer Therapeutics,
Parkville, Victoria. Platelet counts also nadired earlier with
MGDF than with placebo. Importantly, MGDF, in doses up to 5 mcg/kg/day,
was well tolerated when given with G-CSF.