873eP Real-world characteristics and outcomes of patients with third-line or later metastatic colorectal cancer: Magnetic-101 study results

Magnetic-101 was an observational, retrospective cohort study of pts with mCRC in the US that utilized ConcertAI Patient360™ database (Jan 2017–Oct 2024). Adult pts with unresectable mCRC who received ≥3 lines of therapy (LoT) were included; pts with multiple primary cancers or treated in clinical trials were excluded. The study evaluated pt demographics, clinical characteristics, and treatment regimens in 3L+ settings. In the microsatellite stable (MSS) subgroup, defined based on receipt of immunotherapies, real-world (RW) clinical outcomes by LoT, including time to next treatment or death (rwTTNT-D), overall survival (rwOS), and progression-free survival (rwPFS) were explored via Kaplan–Meier methodology.

Overall, 524 pts met eligibility criteria and received 3L+ treatment; 46% were female, 71% White, and 80% were treated in community settings. Median (range) age at initial diagnosis was 61 years (24–78). At 3L initiation, 70% had an ECOG score of 0 or 1. Among 524 3L+ pts, 229 (44%) received 4L and 140 (27%) received 5L+ (including 99 who received 5L). Trifluridine/tipiracil-based treatment was the most commonly used regimen in 3L pts [129 (25%)] and 4L [88 (38%)], and both trifluridine/tipiracil- and regorafenib-based in 5L pts [24 (24%) for each]. In the MSS subgroup (n=473), clinical outcomes were poor (Table); the survival probability of rwOS and rwPFS for 3L, 4L, and 5L+ pts at 4 months was 76% and 35%, 76% and 34%, and 69% and 32%, respectively, and at 6 months was 63% and 20%, 59% and 17%, and 49% and 16%, respectively.

This RW data suggests poor outcomes for pts with 3L+ mCRC on current therapies and an urgent need for novel treatment.