105P - Prospective, open-label, observational study of cetuximab for metastatic colorectal carcinoma (mCRC): The OPTIM1SE study

Background

Cetuximab-based infusional 5-FU regimens are approved for the first-line treatment of mCRC in 116 countries. The OPTIM1SE study observed long-term real-world outcomes of these regimens in routine practice in Australia, South Korea, Malaysia, Singapore, Taiwan, Vietnam, Russia, Lebanon, and Saudi Arabia.

Methods

OPTIM1SE was a prospective, open-label, observational study. Patients with untreated KRAS wild-type mCRC and distant metastases were treated per the locally approved label and monitored for 3 years via hospital, laboratory, and other records. The primary endpoint was overall response rate (ORR) per RECIST 1.1. Safety and other efficacy outcomes were secondary endpoints.

Results

From 19 Nov 2013 to 30 Jun 2016, 520 patients were enrolled by 51 sites. Patients were mostly male (61.2%) with a mean age of 58.5 (±12.0) years; 1.7% were BRAF mutated; 420 patients were treated with FOLFIRI-based regimens and 94 with FOLFOX. The most common primary tumor site was rectum (38.8%) with liver metastases (65.0%). ORR was 45.4% (95% CI, 41.1%-49.7%), including 26 patients (5.0%) with a complete response. Median progression-free survival was 9.9 months (95% CI, 8.2-11.0); median overall survival (mOS) was 30.8 months (95% CI, 27.9-33.6). Patients receiving FOLFIRI-based regimens had better outcomes than those on FOLFOX, including increased ORR (48.6% vs 34.0%) and mOS (31.3 vs 28.6 months). Higher mOS was also associated with tumors of left- rather than right-sided origin (HR 0.69 [95% CI, 0.49-0.99]), and higher ORR with liver metastases compared to all other metastases (55.4% vs 40.2%). Adverse events were consistent with the known safety profile of cetuximab. The most common treatment-related adverse events (TRAE) were rash (20.2%), dermatitis acneiform (16.5%), and paronychia (13.7%); 2.1% of patients had a serious TRAE.

Conclusions

Cetuximab-based 5-FU regimens were effective in treating patients with mCRC, particuarly in those with left-sided disease origin and with liver metastases only, in routine practice. FOLFIRI-based cetuximab regimens were more common and showed improved outcomes over FOLFOX. Our findings are consistent with recent studies.

Clinical trial identification

Editorial acknowledgement

Medical editorial asssistance provided by Kristen Perry and Tim Stentiford, CMPP, of ClinicalThinking, part of Nucleus Global, and was funded by Merck Pte. Ltd.

Legal entity responsible for the study

Merck Pte. Ltd.

Funding

Merck Pte. Ltd.

Disclosure

T.W. Kim: Research grant/Funding (institution): Merck Serono; Research grant/Funding (institution): Sanofi. J.B. Ahn: Research grant/Funding (institution): Sanofi; Research grant/Funding (institution): Boryung. G.F. Ho: Honoraria (self): Roche; Advisory/Consultancy: Pfizer; Advisory/Consultancy: Boehringer Ingelheim; Advisory/Consultancy, Research grant/Funding (institution): Eli Lilly; Research grant/Funding (institution): Merck Sharp & Dohme; Research grant/Funding (institution): Regeneron; Research grant/Funding (institution): Astellas; Research grant/Funding (institution): AB Science; Research grant/Funding (institution): Tessa Therapeutics; Travel/Accommodation/Expenses: Eisai; Travel/Accommodation/Expenses: AstraZeneca; Full/Part-time employment: University Malaya Medical Centre; Full/Part-time employment: UM Specialist Centre. L.T. Anh: Honoraria (self), Honoraria (institution), Advisory/Consultancy, Speaker Bureau/Expert testimony, Travel/Accommodation/Expenses: Merck KGaA; Honoraria (self), Honoraria (institution), Advisory/Consultancy, Speaker Bureau/Expert testimony, Travel/Accommodation/Expenses: Roche; Honoraria (self), Honoraria (institution), Advisory/Consultancy, Speaker Bureau/Expert testimony, Travel/Accommodation/Expenses: AstraZeneca; Honoraria (self), Honoraria (institution), Advisory/Consultancy, Speaker Bureau/Expert testimony, Travel/Accommodation/Expenses: MSD; Honoraria (self), Honoraria (institution), Advisory/Consultancy, Speaker Bureau/Expert testimony, Travel/Accommodation/Expenses: Bayer; Honoraria (self), Honoraria (institution), Advisory/Consultancy, Speaker Bureau/Expert testimony, Travel/Accommodation/Expenses: Pfizer; Honoraria (self), Honoraria (institution), Advisory/Consultancy, Speaker Bureau/Expert testimony, Travel/Accommodation/Expenses: Novartis. S. Temraz: Honoraria (self), Travel/Accommodation/Expenses: BMS; Honoraria (self), Travel/Accommodation/Expenses: Amgen; Advisory/Consultancy, Travel/Accommodation/Expenses: Merck KGaA; Advisory/Consultancy, Travel/Accommodation/Expenses: MSD. M. Burge: Advisory/Consultancy: Merck KGaA. C. Chua: Research grant/Funding (institution): MSD; Travel/Accommodation/Expenses: AstraZeneca; Travel/Accommodation/Expenses: Sanofi; Travel/Accommodation/Expenses: Merck KGaA. J. Huang: Full/Part-time employment: Merck Pte Ltd. Y.S. Park: Advisory/Consultancy: Merck KGaA; Full/Part-time employment: Samsung Medical Center. All other authors have declared no conflicts of interest.