US-based biotechnology firm Gilead Sciences has released interim results of a single-arm, open-label Phase II study of its investigational oral inhibitor of spleen tyrosine kinase (Syk) GS-9973 for treatment of patients with relapsed or refractory haematologic malignancies.
The results demonstrate that 97% (n=28/29) of patients with chronic lymphocytic leukaemia (CLL) who were administered at least eight weeks of GS-9973 monotherapy experienced a reduction in lymph node size.
The primary endpoint of the ongoing trial is progression-free survival and the median age of the patients included in the safety analysis was 72 years.
Willamette Valley Cancer Institute and Research Center director of research Jeff Sharman said most patients with CLL eventually develop resistance to currently available therapies.
"This underscores the importance of identifying new treatments for patients with CLL," Sharman said.
"The B cell receptor signalling pathway is a novel area of focus for investigational therapies in CLL. GS-9973 targets the Syk protein, which initiates most signalling from the B cell receptor.
"Response rates observed in this interim analysis support that GS-9973 has promising clinical activity in CLL to be further explored and developed."
Out of the 29 CLL patients involved in the trial, 20 people (69%) achieved greater than 50% tumour shrinkage, including four of seven patients with a chromosome 17p deletion and/or a mutation in the TP53 gene, genetic abnormalities that have been linked to poor prognosis.
In the trial, the safety of GS-9973 was also evaluated in 78 patients with CLL or non-Hodgkin's lymphoma (NHL) who had received at least four weeks of therapy.
According to the company, at the time of the data cut-off, 50 patients (64%) were continuing with GS-9973 treatment, with a median exposure of ten weeks.
Image: High-magnification micrograph of B-cell chronic lymphocytic leukemia. Photo: courtesy of Nephron.