Triple-agent bortezomib-based regimens yielded no survival or other advantages over a double-agent regimen in a phase-III clinical trial involving transplant-ineligible patients with multiple myeloma. The study was published online June 8 in the Journal of Clinical Oncology.

As the optimal therapy for transplant-ineligible patients has not yet been determined, researchers performed what they described as the first randomized trial comparing several bortezomib-based regimens. For this study, the researchers wanted to assess the regimens in more typical patients: elderly men and women of diverse ethnic and economic backgrounds who have common comorbidities and are treated in community oncology practices.

The 502 participants (mean age, 73 years) in this industry-sponsored study were treated at 159 oncology practices across the country during a 3-year period and followed up for a median of 43 months. Half had serious comorbidities such as diabetes, renal disease, and chronic pulmonary disease. They were randomly assigned to receive eight 21-day cycles of bortezomib-dexamethasone, bortezomib-thalidomide-dexamethasone, or bortezomib-melphalan-prednisone combination induction therapy, followed by five 35-day cycles of maintenance bortezomib, said Dr. Ruben Niesvizky of the myeloma center at New York Presbyterian Hospital and his associates.

The primary efficacy outcome – progression-free survival – was not significantly different among the three study groups at 14.7 months, 15.4 months, and 17.3 months, respectively. Overall response rates were 73%, 80%, and 70%, respectively; complete response rates were 3%, 4%, and 4%, respectively. Also not significantly different between the three groups were duration of response (18.3 months, 22.4 months, and 19.8 months) and median overall survival (49.8 months, 51.5 months, and 53.1 months), the researchers said (J. Clin. Oncol. 2015 June 8 [doi:10.1200/JCO.2014.58.7618]).

Peripheral neuropathy was the most common adverse effect in all three regimens and the most common reason for discontinuing therapy. Both the rates of adverse events and discontinuations due to adverse events were higher for bortezomib-thalidomide-dexamethasone treatment than for the other two regimens. Because of toxicity, only 30% of the total study population completed the full 13 cycles of treatment and only 40% received bortezomib maintenance therapy.

“Our results indicate that the type and number of agents(s) included in combination therapy for elderly persons are important, and offer caution to the current trend of incorporating 3 or even 4 agents into anti-multiple myeloma regimens to boost efficacy without confirmatory randomized studies,” Dr. Niesvizky and his associates noted.


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