One of the study’s primary endpoints was overall response rate, which was 37.1% in the IV arm and 41.1% in the SC arm (relative risk, 1.11; 95% CI, 0.89-1.37; P less than .0001). This met the criteria for noninferiority, and overall response rates were comparable across all patient subgroups, Dr. Mateos noted.
The rates of complete response or stringent complete response were also comparable at 2.7% in the IV arm and 1.9% in the SC arm. Rates of very good partial response were 17.0% and 19.0%, respectively. The study’s other primary endpoint was maximum Ctrough predose on day 1 of cycle 3. The ratio of maximum Ctrough for daratumumab SC over IV was 107.93% (90% CI, 95.74%-121.67%), which met the noninferiority criterion.
Survival outcomes were also similar between the IV and SC arms. The median progression-free survival was 6.1 months and 5.6 months, respectively (P = .9258). The rate of overall survival at 6 months was 83.0% and 87.5%, respectively (P = .6032).
Considering these results together, Dr. Mateos and colleagues concluded that SC daratumumab is noninferior to IV daratumumab.
“[SC daratumumab] has a reduced treatment burden due to a considerably shorter administration duration, and patients treated with [SC daratumumab] reported higher satisfaction with therapy,” Dr. Mateos said.
The results support the use of flat-dose 1,800-mg SC daratumumab, which is comparable with the IV formulation, she said.
The COLUMBA trial was sponsored by Janssen Research & Development. Dr. Mateos reported relationships with Amgen, Celgene, Janssen-Cilag, and Takeda.
SOURCE: Mateos MV et al. ASCO 2019,