ATLANTA ( TheStreet) -- A new version of Takeda's multiple myeloma injection Velcade, re-engineered as a once-weekly pill, may be more effective and better tolerated, according to data presented Sunday from a mid-stage study. In the phase II study, patients with newly diagnosed multiple myeloma were treated with a combination of oral drugs consisting of Takeda's MLN9708, Celgene's ( CELG) Revlimid and the steroid dexamathesone. The overall response rate was 90%, including complete response rate of 23% and a "very good partial response" rate of 58%. The study continues and response rates are increasing along with the number of treatment cycles. "These results are similar to what we see with the Velcade combination regimen," said study investigator Dr. Shaji Kumar of the Mayo Clinic, referring to the combination of Velcade, Revlimid and dexamethasone used commonly today in the U.S. to treat multiple myeloma patients. Kumar cautioned, however, that the MLN9708 study is only halfway completed. Patients will need to be treated longer and survival data will need to be collected and analyzed before more definitive comparisons between MLN9078 and Velcade can be made. Kumar is presenting results from the MLN9708 phase II study at the American Society of Hematology (ASH) annual meeting taking place in Atlanta. Multiple myeloma causes plasma cells found in the bone marrow to grow unchecked and form tumors. MLN9708 is being developed to improve upon the efficacy and safety of injectable Velcade, with the convenience of a pill formulation as an added bonus, said Dixie Esseltine, vice president of global medical affairs at Millennium Pharmaceuticals, the U.S.-based oncology arm of Takeda. Millennium developed Velcade and got the drug approved to treat multiple myeloma in 2003. Takeda acquired Millennium in 2008. U.S. sales of Velcade U.S. totaled $744 million in 2011. Velcade works by blocking the function of proteasomes, cell structures that play a role in cell function and growth. Inhibiting proteasome activity retards certain proteins that help myeloma cells survive. MLN9708 is also a proteasome inhibitor but was engineered with a different structure that makes it both oral and potentially superior to Velcade, Esseltine said.
The most significant safety drawback of Velcade is peripheral neuropathy, or nerve damage to that causes numbness and pain. In the phase II study of MLN9708, 32% of patients reported peripheral neuropathy, although most cases were minor. Two patients in the study, or 3%, reported more serious "grade 3" peripheral neuropathy. Kumar called the relatively low incidence of serious peripheral neuropathy in the MLN9708 study "encouraging" and suggests that the drug's better tolerability profile could lead to longer treatment duration and better response rates. The most common adverse events associated with MLN9708 were vomiting, diarrhea and rash occurring in about 40% of patients. Takeda is conducting two phase III studies of MLN9708 in relapsed refractory multiple myeloma and amyloidosis, respectively. A third phase III study of MLN9708 in newly diagnosed multiple myeloma will begin next year. Onyx Pharmaceuticals ( ONXX) is developing its own oral proteasome inhibitor, known as oprozomib, and early stage data is being presented at this week's ASH meeting as well. Onyx's first proteasome inhibitor Kyprolis, which like Velcade is given via injection, was recently approved for the treatment of multiple myeloma and early sales have been strong. -- Reported by Adam Feuerstein in Boston. Follow @AdamFeuerstein