A Phase II trial of weekly bortezomib and dexamethasone in veterans with newly diagnosed multiple myeloma not eligible for or who deferred autologous stem cell transplantation

Once-weekly administration of bortezomib has reduced bortezomib-induced peripheral neuropathy without affecting response rates, but this has only been demonstrated prospectively in three- and four- drug combinations. We report a phase II trial of alternate dosing and schedule of bortezomib and dexamethasone in newly diagnosed multiple myeloma patients who are not eligible for or refused autologous stem cell transplantation. Bortezomib 1·6 mg/m² intravenously was given once-weekly for six cycles, together with dexamethasone 40 mg on the day of and day after bortezomib. Fifty patients were enrolled; 58% did not require any dose modification. The majority of patients had multiple co-morbidities, including cardiovascular (76%) and renal insufficiency (54%), and the median number of medications prior to enrollment was 13. Of all evaluable patients, the overall response rate was 79% and at least 45% had at least a very good partial response. The median time to first response was 1·3 months (range, 0·25-2·4 months). The progression-free and overall survivals were 8 months and 46·5 months, respectively. Twenty-four percent developed worsening neuropathy. We conclude that alternate dosing and scheduling of bortezomib and dexamethasone is both safe and effective for management of newly diagnosed multiple myeloma in frail patients.