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