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In patients with metastatic colorectal cancer who received cetuximab as a second-line therapy after irinotecan or oxaliplatin-based regimens have failed, KRAS mutational status and geographical region were associated with time on treatment, while body mass index and age were linked with overall survival.
In patients with metastatic colorectal cancer (mCRC) who received cetuximab (Erbitux) as a second-line therapy after irinotecan or oxaliplatin-based regimens have failed, KRAS mutational status and geographical region were associated with time on treatment (TOT), while body mass index (BMI) and age were linked with overall survival (OS), according to data from a real-world retrospective analysis.
Results, which were presented during the 2021 ASCO Annual Meeting,indicated that the median TOT in patients who received second-line cetuximab was 3.94 months (median interquartile range [mIQR], 3.51-4.40), while the median OS was 14.36 months (mIQR, 13.01-15.70).
Moreover, receiving second-line treatment with cetuximab plus FOLFIRI (median TOT = 4.43 months; mIQR, 3.71-5.36), having KRAS wild-type status, and receiving second-line cetuximab following frontline capecitabine plus oxaliplatin (CAPOX), were all associated with a longer median TOT. Moreover, residing in the South region vs the Midwest of the United States was linked with a shorter median TOT.
Having a higher BMI was associated with a longer median OS (obese vs underweight HR, 0.46; 95% CI, 0.32-0.66), while receiving treatment with second-line cetuximab plus 5-fluorouracil, leucovorin, and oxaliplatin (FOLFOX) was linked with a shorter median OS (10.97 months; mIQR, 5.55-14.06). Additionally, being older than 65 years was also linked with a shorter median OS (≥65 years vs <65 years; HR, 1.24; 95% CI 1.05-1.46).
Anti-epidermal growth factor receptor drugs are being increasingly utilized in later lines of therapy in patients with mCRC, but the real-world TOT and OS of patients who receive cetuximab in second-line setting has not been examined. As such, investigators set out to examine characteristics linked with TOT and OS using retrospective observational data.
Between January 2013 and August 2020, 1011 patients were selected from the nationwide Flatiron electronic health record database. Patients were included in the analysis if they had a mCRC diagnosis, received second-line treatment with a cetuximab-based regimen, and had progressed on oxaliplatin/irinotecan-based regimens in the frontline.
Investigators defined TOT as the time from start of cetuximab in the second line to the last date of evidence of administration. Moreover, end of treatment was defined if patients progressed to a third line of therapy or if they had a death record. Additionally, OS was calculated from index date to the date of death or censored to the last visit date available.
Among the 1011 patients included in the analysis, more than half were younger than 65 years (58%) and male (60%). Additionally, most patients had a median BMI of 26.6 kg/m², had previously received FOLFOX regimens in the first-line setting (61%), and received treatment in the community setting (96%). The most frequently used second-line treatment regimens were cetuximab plus FOLFIRI (46%) and cetuximab plus irinotecan (29%).