The addition of monoclonal antibodies against epidermal growth factor receptor (anti-EGFR Abs) to chemotherapy is commonly delayed in the real-world clinical practice, usually because of delays in obtaining RAS testing results. The aim of this retrospective registry-based analysis was to determine whether the delayed addition of anti-EGFR mAbs up to the fourth cycle of backbone chemotherapy adversely affects outcomes of mCRC patients treated with first-line regimens.
Clinical data of patients with RAS wild-type mCRC treated with first-line systemic therapy regimens containing anti-EGFR mAbs from a national database were analysed retrospectively. Patients were divided into three groups according to the timing of anti-EGFR mAbs addition to the chemotherapy backbone. Cohort A (n = 401) included patients with anti-EGFR mAbs added to chemotherapy from the first cycle, cohort B (n = 71) patients with anti-EGFR mAbs added to chemotherapy from the second cycle, and cohort C (n = 101) patients who had anti-EGFR mAbs added to chemotherapy from the third or fourth cycle. The chemotherapy backbone regimens consisted of FOLFOX or FOLFIRI regimens.
336 (58.6%) patients received panitumumab and 237 (41.4%) patients received cetuximab. The median progression-free survival (PFS) of the whole cohort was 12.2 months (95% confidence interval [CI] 10.9–13.5), and the median overall survival (OS) was 33.5 months (95% CI 27.6–39.4). Survival results for the cohorts defined by the time of addition of anti-EGFR MoAbs to chemotherapy are shown in the table. In a multivariate test, ECOG performance status and chemotherapy regimen were associated with PFS, whereas the site of primary tumour and chemotherapy regimen were associated with OS.Table: 491P
|Cohort||PFS (95% CI), months||Log-rank p-value||OS (95% CI), months||Log-rank p-value|
|A (n = 401)||12.9 (11.5–14.3)||30.6 months (25.2–36.1)|
|B (n = 71)||9.7 (9.1–10.3)||A vs. B p = 0.185||Not reached||A vs. B p = 0.645|
|C (n = 101)||11.5 (9.8–13.2)||A vs. C p = 0.826||37.9 months (28.6–47.3)||A vs. C p = 0.052|
Delayed addition of anti-EGFR mAbs up to the fourth cycle of first-line chemotherapy was not associated with inferior survival or response rates.
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Legal entity responsible for the study
The institute of Biostatistics and Analysis, Faculty of Medicine, Masaryk University, Brno received financial support for the CORECT registry from Bayer, Amgen, Merck, and Roche.
T. Buchler, O. Fiala: Research funding, Travel grants, honoraria: Roche, Merck, Bayer, Servier, BMS, MSD, Sanofi, Amgen. A. Poprach: Honoraria, travel grants: Roche, Amgen. I. Kiss: Speakers’ honoraria: Roche, Merck, Amgen. J. Finek: Lecture honoraria, travel grants: Roche, Merck, Pfizer, Novartis, Amgen. B. Melichar: Research funding, travel grants, Honoraria: Roche, Merck, Bayer, Servier, BMS, MSD, Sanofi, Amgen. All other authors have declared no conflicts of interest.