120P - Improved clinical outcomes with cetuximab maintenance therapy in left-sided RAS/BRAF wild-type metastatic colorectal cancer: A real-world study of Hunan cancer hospital

Background

Cetuximab (Cet) plus chemotherapy (CT) has been approved as preferred first-line (1L) treatment for left-sided (LS) metastatic colorectal cancer (mCRC) with wild-type (wt) RAS/BRAF gene. However, it remains uncertain whether Cet is beneficial as maintenance therapy after 1L treatment. This study aimed to investigate the clinical outcomes for maintenance therapy in pts with LS RAS/BRAF wt mCRC who responded to 1L Cet plus CT.

Methods

We performed a retrospective review of pts with LS RAS/BRAF wt mCRC who had disease controlled (CR, PR or SD) after 6 cycles of Cet based induction therapy from JAN 2018 to JUN 2022 at HuNan Cancer Hospital. The 1L regimen consists of Cet plus mFOLFOX6 or FOLFIRI, based on pts selection, followed by maintenance therapy with Cetuximab with or without chemotherapy (cohort A) or chemotherapy alone (cohort B). Death data were obtained from the government's death registry. Kaplan-Meier methods were employed to describe overall survival (OS) and progression-free survival (PFS).

Results

A total of 125 pts were included in this study, with 72 (57.6%) in cohort A and 53 (42.4%) in cohort B. The median age was 58 years (range: 23-76), and 86 (68.8%) were male. The most common site of metastasis was the liver (90 patients, 72.0%). During a median follow-up of 32.6 m, the median OS from the start of 1L therapy was significantly longer in cohort A (46.4 m, 95% CI 40.1-NA) than in cohort B (31.1 m, 95% CI 27.6-38.0; p < 0.0001). Similarly, cohort A (14.2 m, 95% CI 12.4-17.0) had a significantly longer median PFS than cohort B (11.0 m, 95% CI 9.6-11.7; p=0.021). The Cox proportional hazards model, after adjusting for age, sex, primary tumor location, metastatic site, and whether the primary tumor and metastases were resected or not, showed that compared with cohort B, cohort A was associated with a statistically significant longer OS (HR 0.43, 95% CI 0.25-0.73) and a longer PFS, although the difference was not statistically significant (HR 0.70, 95% CI 0.44-1.12).

Conclusions

Maintenance therapy with Cet can significantly improve OS in pts with LS RAS/BRAF wt mCRC and lead to a clinically meaningful improvement in PFS, although the statistical difference was not reached.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.