* Revlimid found to interact with P-glycoprotein
* Study urges caution with Revlimid dosing
LOS ANGELES, Aug 8 (Reuters) - An early-stage trial of Celgene Corp’s CELG.O multiple myeloma drug Revlimid has found that it interacts with another protein that affect its dose levels in the body as well as potential side affects, according to researchers.
Revlimid, also known as lenalidomide, was approved by the U.S. Food and Drug Administration in 2005 for treating myelodysplasia syndromes and in 2006 for multiple myeloma.
Celgene is also seeking to win approval of the drug as a maintenance therapy following a stem cell transplant.
Researchers at the Ohio State University Comprehensive Cancer Center found that lenalidomide interacts with P-glycoprotein (Pgp), a molecule that pumps potentially toxic chemicals out of cells and aids in removing them from the body.
The findings, published online in the Journal of Clinical Oncology, could lead to safer dosing of lenalidomide in a variety of diseases, the researchers said in a statement.
The team at Ohio State University conducted a Phase 1 trial of lenalidomide in combination with temsirolimus, which is sold by Pfizer Inc (PFE.N) under the brand name Torisel, in 21 patients with relapsed multiple myeloma, a type of blood cancer that affects more than 20,000 Americans each year.
The study found that lenalidomide levels in patients’ blood were often higher than expected, and some patients experienced increased side effects such as electrolyte imbalances and rashes.
Laboratory experiments showed that lenalidomide was removed from cells by Pgp, and the rate of removal was reduced when temsirolimus, which is known to interact with Pgp, was included in the experiments.
“It is unusual to discover several years after FDA approval that a drug interacts with Pgp,” Dr. Mitch Phelps, assistant professor in Ohio State’s College of Pharmacy, said in a statement.
He said the delay probably occurred because the drug is predominantly excreted by the kidneys into the urine. This had been assumed to be through filtration, which is a passive process independent of Pgp or other transporter proteins.
“Although the kidneys may have the primary job of eliminating lenalidomide, our findings indicate that Pgp and other factors may also significantly contribute,” Dr. Phelps said, adding that more study is needed.
Reporting by Deena Beasley