MONARCC: a randomised phase II study of panitumumab monotherapy and panitumumab plus 5-fluorouracil as first-line therapy for RAS and BRAF wildtype metastatic colorectal cancer: a study by the Australasian Gastrointestinal Trials Group (AGITG).

Background: Doublet chemotherapy in combination with a biologic agent has been a standard of care in patients with metastatic colorectal cancer for over a decade. The evidence for a "lighter" treatment approach is limited to mono-chemotherapy plus bevacizumab in the RAS unselected population. Anti-EGFR antibodies have activity as monotherapy or in combination with chemotherapy in RAS wildtype metastatic colorectal cancer; however their role in first-line treatment in combination with 5-fluorouracil monotherapy or when given alone has not been well studied. MONARCC aims to investigate this approach in an elderly population. Methods/design: MONARCC is a prospective, open-label, multicentre, non-comparative randomised phase II trial. Eligible patients aged >=70 with unresectable metastatic, untreated, RAS/BRAF wildtype metastatic colorectal cancer will be randomised 1:1 to receive panitumumab alone or panitumumab plus infusional 5-fluorouracil. RAS and BRAF analyses will be performed in local laboratories. Comprehensive Health Assessment and Limited Health Assessments will be performed at baseline and at 16 weeks, respectively, to assess frailty. The Patient Symptom Questionnaire and Overall Treatment Utility are to be undertaken at different timepoints to assess the impact of treatment-related toxicities and quality of life. Treatment will be delivered every 2 weeks until disease progression, unacceptable toxicity (as determined by treating clinician or patient), delay of treatment of more than 6 weeks, or withdrawal of consent. The primary end point is 6-month progression-free survival in both arms. Secondary end points include overall survival, time to treatment failure, objective tumour response rate as defined by RECIST v1.1 and safety (adverse events). Tertiary and correlative endpoints include the feasibility and utility of a comprehensive geriatric assessment, quality of life and biological substudies. Discussion(s): MONARCC investigates the activity and tolera