In the phase 3 CodeBreaK 300 study, sotorasib (KRAS^G12C inhibitor) plus panitumumab (EGFR inhibitor) significantly prolonged progression-free survival versus investigator’s choice of trifluridine–tipiracil or regorafenib (standard of care) in patients with KRAS^G12C-mutated chemorefractory metastatic colorectal cancer. This analysis evaluated patient-reported outcomes (PROs) as secondary and exploratory endpoints.

In this open-label, randomised clinical trial, adult (aged ≥18 years) patients from 67 centres in 13 countries in Asia, Australia, Europe, and North America with KRAS^G12C-mutated chemorefractory metastatic colorectal cancer (as assessed by central molecular testing of tumour biopsy specimens) who were KRAS^G12C inhibitor-naive, had progressed to recurrence after previous therapy with fluoropyrimidine, oxaliplatin, and irinotecan, with measurable disease according to the Response Evaluation Criteria in Solid Tumors version 1.1, and with an Eastern Cooperative Oncology Group (ECOG) performance status score of 0, 1, or 2, were enrolled. Patients were randomly assigned 1:1:1 using interactive response technology to receive sotorasib 960 mg (daily, orally)–panitumumab (6 mg/kg every 2 weeks, intravenous infusion), sotorasib 240 mg (daily, orally)–panitumumab (6 mg/kg every 2 weeks, intravenous infusion), or investigator’s choice of trifluridine–tipiracil (35 mg/m² [up to 80 mg per dose] on days 1–5 and 8–12 twice a day, orally) or regorafenib (160 mg daily for the first 21 days, orally). Randomisation was stratified by by previous anti-angiogenic therapy, time from initial diagnosis of metastatic disease to randomisation, and ECOG performance status. The primary endpoint was progression-free survival (reported previously). PROs included fatigue at its worst according to the Brief Fatigue Inventory, pain at its worst according to the Brief Pain Inventory (where lower score is better), and Global Health Status–Quality of Life (GHS–QoL) and physical function subscales of European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (where higher score is better) assessed via validated PRO questionnaires, administered at baseline, day 1 of each 4-week cycle until disease progression, and safety follow-up. Analyses were conducted in a modified intention-to-treat population. Least squares mean changes from baseline to week 9 were estimated using a mixed effects model for repeated measures. Time to deterioration (TTD), change in overall status, and patient-reported tolerability were also evaluated as prespecified exploratory outcomes. TTD was summarised using a stratified Cox proportional hazards model and Kaplan–Meier curve. Change in overall status and patient-reported tolerability were also summarised descriptively over time. The study is registered with ClinicalTrials.gov, NCT05198934, and prespecified analyses are completed.

Between April 19, 2022, and March 14, 2023, 160 patients were enrolled and randomly assigned to receive sotorasib 960 mg–panitumumab (n=53), sotorasib 240 mg–panitumumab (n=53), and investigator’s choice (n=54). Median duration of treatment was 6·0 months (IQR 3·7–7·0), 4·6 months (3·3–6·2), and 2·2 months (1·8–4·2) in these groups, respectively. 81 (51%) patients in the study were female; 109 (68%) patients were White, 40 (25%) were Asian, one (1%) was Black, and ten (6%) were of another race or not reported; 12 (8%) were Hispanic or Latino and three (2%) were of unknown ethnicity. Compliance rates for PRO assessments at week 9 were high (approximately 80%) and similar across treatment groups. Least squares mean changes in PROs at week 9 favoured the two sotorasib groups. Differences in changes from baseline for sotorasib 960 mg–panitumumab and sotorasib 240 mg–panitumumab (both vs investigator’s choice), respectively were: –0·89 (95% CI –1·80 to 0·01) and –0·58 (–1·47 to 0·30) for fatigue at its worst, –1·45 (–2·32 to –0·58) and –1·14 (–2·00 to –0·28) for pain at its worst, 9·43 (2·31 to 16·56) and 6·49 (–0·43 to 13·41) for GHS–QoL, and 5·38 (–0·01 to 10·78) and 6·34 (1·07 to 11·62) for physical function.

Along with improved clinical outcomes, these analyses suggest that sotorasib plus panitumumab could represent a valuable new treatment in patients with KRAS^G12C-mutated chemorefractory metastatic colorectal cancer.

Amgen.