Characteristics, Treatment Patterns, and Outcomes of Patients with Multiple Myeloma Retreated with Daratumumab in Real-World Clinical Practice in the USA

Background: Daratumumab (DARA) has demonstrated clinical benefit in multiple myeloma (MM) and is approved for the treatment of both newly diagnosed MM (NDMM) and relapsed refractory MM (RRMM). While single-center studies have shown the benefit of DARA retreatment in patients (pts) who are refractory to DARA (D-Ref), there is a lack of real-world data on the characteristics of pts who are retreated with DARA across multiple lines of treatment (LOTs). In this study, we examine DARA retreatment patterns and outcomes among pts who are D-Ref and those who are sensitive to DARA (D-Sens) after the first DARA exposure in the US real-world clinical practice.

Methods: This study used the Flatiron MM Core Registry data to identify pts with MM treated with a DARA-containing regimen in ≥2 separate LOTs between November 1, 2015, and March 31, 2024. The first DARA-based LOT was defined as D1, and the second DARA-based LOT was defined as the retreatment LOT (D2). The following criteria, developed by Janssen Scientific Affairs, were used to classify pts as Dara-retreated: 1) pts treated with the same DARA-containing regimens in consecutive LOTs were classified as Dara-retreated if there was a gap of >90 days between D1 and D2, 2) pts treated with different DARA-containing regimens in consecutive LOTs were classified as Dara-retreated, 3) pts treated with DARA-containing regimens had ≥1 LOTs between D1 and D2 they were classified as Dara-retreated, regardless of whether the regimens were the same or different. Derived disease progression reported in the Flatiron data was used for this analysis. If disease progression was reported during D1, or within 60 days of discontinuing D1, the pt was considered as D-Ref, otherwise, the pt was considered as D-Sens. Kaplan-Meier (KM) analyses were conducted to evaluate duration of D2, proportion of pts not receiving subsequent treatment after D2, and progression-free survival (PFS) rates during D2.

Results: Data for 201 pts retreated with DARA were identified in this analysis, 150 were D-Sens and 51 were D-Ref. In the D-Sens group, the median age at D2 initiation was 71 years, 44.0% of pts were female, 27.3% were ISS stage II and 16.0% were African American. In the D-Ref group, the median age at D2 initiation was 67 years, 45.1% of pts were female, 21.6% were ISS stage II, and 25.5% were African American. At D2 initiation, 64.7% (D-Sens) and 60.8% (D-Ref) of pts were frail, and 56.0% (D-Sens) and 52.9% (D-Ref) of pts had a Quan-Charlson Comorbidity Index of ≥3, indicating a high burden of comorbidities. About 31% of pts in both groups had high cytogenetic risk abnormalities, and about 20% had a 1q21 gain or amplification. The median time from MM diagnosis to start of D1 and to start of D2 was shorter in the D-Sens group (10.8 and 34.9 months) than in the D-Ref group (18.4 and 44.4 months). D-Sens pts were less likely to receive D1 in the third LOT or later compared to D-Ref pts (30.0% vs 45.1%). The median number of LOTs before D2 was three in both groups. The median gap between D1 and D2 was 9.3 months in D-Sens pts and 9.0 months in D-Ref pts, however, more D-Sens pts received D1 and D2 LOTs consecutively compared to D-Ref pts (62.0% vs 51.0%). The most common regimen used in D1 was DARA + lenalidomide + dexamethasone (dex; 18.7%) and DARA + bortezomib + dex (18.7%) among D-Sens pts, and DARA + pomalidomide + dex (23.5%) among D-Ref pts. The most common regimen used in D2 was DARA mono (31.3%) in D-Sens pts, and DARA mono (17.6%) and DARA + carfilzomib + dex (17.6%) in D-Ref pts. Overall, 32.0% of D-Sens and 35.3% of D-Ref pts received agents from the same drug class in D1 and D2. The KM median duration of D2 was 7.4 months (95% CI: 5.5-9.5) among D-Sens pts and 6.4 months (95% CI: 3.8-23.5) among D-Ref pts. The proportion of pts that had not received subsequent treatment after D2 was 38.7% and 29.5% at 12 months in the D-Sens and D-Ref groups, respectively. PFS rates at 12 months after D2 initiation were 77.1% in the D-Sens group and 49.4% in the D-Ref group.

Conclusion: DARA retreatment is utilized frequently and is effective in the real-world, suggesting the ability to use this approach in subsequent LOTs among pts with RRMM. In the absence of other feasible alternatives, this may be a treatment strategy for patient benefit, regardless of whether they are D-Sens or D-Ref. Future studies are needed to definitively investigate the benefit of DARA retreatment in combination with drugs with novel mechanisms of action.