Three Papers Look at Efficacy of Idelalisib in CLL, iNHL and MCL

Three papers appearing in the journal Blood and pointing towards a regulator-suppressor pill could offer hope to blood cancer patients whose treatment options have dwindled.

The pill in question is idelalisib. Idelalisib is a highly selective targeted treatment compound that hones in on a specific mechanism that fuels cancer growth. Taken orally, idelalisib first targets and then blocks the expression of the delta isoform of the PI3 kinase enzyme, which is critical for the activation and survival of cancerous B cells.

This rather narrow target field makes the drug especially appealing in patients with cancers that have developed along the B-cell pathway, including chronic lymphocytic leukemia, some indolent non-Hodgkin's lymphomas, and mantle cell lymphoma. The FDA is currently reviewing the drug for the treatment of treatment-resistant iNHL.

"Idelalisib is a part of a revolutionary new class of treatments that can hone in on a specific target without causing the wide range of side effects seen with chemotherapy," said study author Jennifer R. Brown, M.D., Ph.D., Director of the Chronic Lymphocytic Leukemia Center at Dana-Farber Cancer Institute in Boston.

The three papers in Blood explore data from a large Phase I study evaluating the safety and efficacy of idelalisib in more than 150 heavily pretreated patients with CLL, iNHL, and MCL. Patients were separated into their own specific disease cohorts and the following response rates (either complete or partial) were recorded:

• CLL patients, 72 percent
• iNHL patients, 47 percent
• MCL patients, 40 percent

Adding to this, patients with MCL experienced very short response duration times, leading researchers to suggest that it was not likely the drug would be approved to treat MCL. That did not however dim the enthusiasm of the research teams.

"Considering the high number of previous therapies that these patients had received, higher than we sometimes see in comparable studies, the efficacy of idelalisib that we observed was remarkable," added study author Ian Flinn, M.D., Ph.D., Director of the Hematologic Malignancies Research Program at Sarah Cannon Research Institute in Nashville. "It was this initial excitement that has inspired further studies of this therapy in patients with treatment-resistant blood cancers."

Source: Science Codex