Initial data from a phase I-II trial show that bortezomib, lenalidomide, and dexamethasone produce a very high response rate in patients with newly diagnosed multiple myeloma, according to a presentation at the annual meeting of the American Society of Hematology.

The three-agent regimen of bortezomib, lenalidomide, and dexamethasone achieved an overall response rate of 98 percent in 42 patients evaluated thus far in the trial, said Paul Richardson, MD, of Dana-Farber Cancer Center and the study's principal investigator. He added that 52 percent of patients had high quality responses (very good partial response or better), with 30 percent achieving complete response.

"These may be some of the best response rates we've seen to date with up-front therapies, and although these are preliminary results, they are extremely promising," Richardson said. The patients were previously untreated when they received the trial combination.

Bortezmib is a proteasome inhibitor, which blocks the myeloma cells' waste disposal system, creating an accumulation of toxic compounds that poison the cell. Lenalidomide is a chemical relative of thalidomide that affects several pathways in cancer cells, including immune mechanisms and blood vessel growth to tumors.

The same three-agent combination had already been shown to be effective for multiple myeloma patients who had relapsed following successful treatment or who had not responded to standard therapies.

The responses, he added, appear to be holding up well, with a duration of more than one year for some patients to date. The trial continues to enroll patients, and final results are expected next year.