Bortezomib-Based Therapy Effective for Relapsed/Refractory Myeloma

Relapsed or refractory multiple myeloma patients experience high response rates, overall survival with bortezomib-based therapy.

A group of “real-world” patients with relapsed or refractory multiple myeloma had high response rates and an overall survival (OS) of about 3 years when treated with bortezomib-based therapy, according to results of the electronic Velcade Observational Study (eVOBs).

“While the benefits of bortezomib-based therapy have been exemplified in clinical trials, use of bortezomib for RRMM [relapsed/refractory multiple myeloma] in real-world medical practice has rarely been studied prospectively,” Evangelos Terpos, of the National and Kapodistrian University of Athens School of Medicine, and colleagues, wrote in the European Journal of Haematology. “Robust, real-world evidence is becoming increasingly important as the efficacy and safety of bortezomib in the treatment of RRMM as reported in the highly controlled clinical trial setting may differ from experience in everyday oncology practice.”

The open-label, observational, multicenter study included 873 patients scheduled to receive intravenous bortezomib for relapsed or refractory myeloma. Patients had a median of two lines of therapy prior to initiating bortezomib; 30% of the patients had thalidomide-based treatment, 22% had melphalan-based treatment, and 12% had cyclophosphamide/vincristine/doxorubicin/dexamethasone–based therapy.

Sixty-nine percent of patients responded to treatment, including 37% with a complete or near-complete response. The median time to response was 1.8 months, and the median time to next therapy was 9.7 months. Patients had a median treatment-free interval (TFI) of almost 8 months.

After 22.6 months' follow-up, the median progression-free survival (PFS) was 12 months and the median OS was 36.1 months.

“Survival outcomes in eVOBs appeared more favorable than previous prospective observational studies of bortezomib-based therapy for relapsed refractory multiple myeloma and less favorable than more recent clinical trials,” the researchers wrote. “The more favorable survival outcome in recent trials could be a result of greater diversity of bortezomib-based regimens available, use of bortezomib in earlier lines of therapy, physicians’ increased experience with bortezomib, and possibly better salvage therapies, compared with when eVOBS was conducted.”

Those patients who achieved complete or near-complete response had significantly longer PFS and OS compared with minimal response or worse (P < .0001 for both). In addition, better survival was observed in patients with baseline creatinine clearance level of 60 mg/dL or greater, those aged younger than 65 years, those who received bortezomib in first or second-line treatment, and those with earlier-stage disease.

“Adverse events reported in this study were consistent with the known safety profile of bortezomib in the clinical trial setting, with no new or unexpected safety signals,” the researchers wrote.

The most common grade 3 or worse adverse events were thrombocytopenia (8%) and anemia (6%). The most common serious adverse events were pneumonia (6%), thrombocytopenia (3%), infection (2%), and pyrexia (2%). About one in four (26%) patients discontinued bortezomib due to adverse events.

“Even in the setting of more recently available treatment options, these findings support the continued use of bortezomib-based treatment as a standard-of-care treatment option in the relapsed refractory multiple myeloma setting,” they concluded.