Uncovering Novel Data on Myeloma Patients Treated With Proteasome Inhibitors

Researchers uncovered distinct clinical characteristics in a German population of relapsed/refractory multiple myeloma (RRMM) patients selected to receive proteasome inhibitor–based therapy, according to the results of a study (abstract 1953) presented at the American Society of Hematology (ASH) 2018 Annual Meeting & Exposition, held December 1–4 in San Diego.

In patients with RRMM, proteasome inhibitors are a big step forward in treatment. Although three proteasome inhibitors were available in Germany in 2017-including bortezomib, carfilzomib, and ixazomib-little data exist regarding use. In the current study, the researchers, led by H. Tilman Steinmetz of the Center for Hematology and Oncology in Cologne, explored clinical characteristics and treatment experiences for RRMM patients treated with proteasome inhibitors.

Steinmetz and colleagues mined medical charts for patients treated with a minimum of one proteasome inhibitor–based regimen between January and June 2017. They collected the following data until either April 2018 or patient death: patient demographics, disease characteristics, and treatment history at diagnosis and at start of proteasome inhibitor–based treatment. Treatment responses were then analyzed.

In the study, 302 patient charts were assessed, including 219 patients receiving second-line treatment and 83 patients receiving third-line treatment. They found that patients administered novel proteasome inhibitors in the second line were, for the most part, younger and more transplanted vs bortezomib-treated patients, which, according to the researchers, appears to be an important consideration when designing therapies for RRMM. Additionally, the choice between triplet or doublet therapy for carfilzomib-based combinations reflected prior transplant status and overall functional performance of the patients. Finally, data suggest that the use of novel proteasome inhibitors including carfilzomib can yield deeper second-line responses.

According to the authors, the study did have limitations. “The main limitation of the study was the sample size of ixazomib-treated patients, due to open inclusion criteria to select patient charts,” they wrote. “This analysis was not powered to compare between proteasome inhibitors. Hence, results are descriptive of the clinical experience with proteasome inhibitor–based therapy to date and reflect current treatment practices in Germany in 2017.”

Outside experts were intrigued by the results of this study. “It’s very interesting that a large proportion of the carfilzomib patients, who had previously been treated with bortezomib, an agent with a similar mechanism of action, experienced very good partial response/complete response,” said Haris Vikis, PhD, a senior consultant at Kantar Health.

Martin Gramatzki, MD, of the division of stem cell transplantation and immunotherapy at the University Hospital Schleswig-Holstein and University of Kiel, told Cancer Network, “This real-world research is very valuable.”