By Bill Berkrot
(Reuters) - Most newly diagnosed patients with the blood cancer multiple myeloma had a very strong response to an experimental oral drug being developed by Takeda Pharmaceutical Co when given in combination with standard treatments, according to data from a study presented on Monday.
Overall, 94 percent of the 62 patients in the Phase I/II trial had their cancer respond to Takeda's MLN9708 taken twice a week in combination with Celgene Corp's Revlimid and the corticosteroid dexamethasone.
The rate of those who had either a complete response or very good partial response was an impressive 76 percent, researchers said. Complete response was defined as no detectable disease in the blood or bone marrow, while a partial response was considered very good if a particular protein the cancer cells produce was reduced by at least 90 percent.
"We're very excited about the data around MLN9708," Dr. Paul Richardson, the study's lead investigator from the Dana-Farber Cancer Institute in Boston, said in a telephone interview.
"It basically demonstrates that when you combine it with the new gold standard, which is Revlimid and dexamethasone, we see very high quality of responses," said Richardson, who presented the data at the American Society of Hematology meeting in New Orleans. "And the quality of the responses gets better over time."
Of the patients who experienced a complete response to the three-drug regimen, three quarters had what researches termed a stringent complete response. That is a newer method of disease detection in which researchers can go into the bone marrow and assess plasma cells to make sure there is no evidence of any cancer cells left behind, Richardson explained.
Patients in the study received the three-drug combination for up to 16, 21-day cycles followed by maintenance with the Takeda drug until the disease progressed or there was evidence of unacceptable toxicity.
About 15 percent of patients discontinued treatment due to adverse side effects - a rate Richardson called relatively low.
Major side effects were mild to moderate, he said, noting that common adverse reactions, such as rash and gastrointestinal toxicity, such as nausea, were manageable.
"I think the tolerability profile is excellent," Richardson said.
MLN9708 belongs to a class of medicines called proteasome inhibitors of which several companies are developing oral versions. Takeda's is currently the farthest along with Phase III studies underway testing once a week dosing in previously untreated patients and those who have relapsed or failed to respond to prior therapies, the Japanese drugmaker said.
Asked how 9708 compares with Takeda's widely used injectable medicine Velcade, Richardson said the new oral drug is more widely distributed throughout the body, rather than more of a bone marrow based response.
"It appears to partner well with other drugs that are effective, and most importantly, we are seeing response rates and quality of responses that are comparable to our most effective IV regimens," Richardson said.
"I'm very excited about all these new oral proteasome inhibitors," he said. "All oral is remarkably convenient. The patients will love it."
(Reporting by Bill Berkrot; Editing by Bernard Orr)