Rechallenge with Anti-EGFR Treatment in RAS/BRAF wt Metastatic Colorectal Cancer (mCRC) in Real Clinical Practice: Experience of the GITuD Group

BACKGROUND

There are few third- and fourth-line therapeutic options for metastatic colorectal cancer (mCRC). In RAS/BRAF wild-type (wt) mCRC previously treated with anti-epidermal growth factor receptor (anti-EGFR) (first-line) and relapsed after a good response, retreatment with anti-EGFR (rechallenge) emerges as a therapeutic alternative.

OBJECTIVE

The aim was to show the activity and safety of anti-EGFR rechallenge in RAS/BRAF wt mCRC in real-world practice.

PATIENTS AND METHODS

A multicenter, retrospective, observational study (six hospitals of the Galician Group of Research in Digestive Tumors) was conducted. Adult patients with RAS/BRAF wt mCRC, evaluated by liquid biopsy, were included. They received anti-EGFR rechallenge (cetuximab, panitumumab) as monotherapy, or combined with chemotherapy, in third- or subsequent lines. Efficacy (overall response rate [ORR], disease control rate [DCR], overall survival [OS], and progression-free survival [PFS]) and safety (incidence of adverse events [AEs]) were assessed.

RESULTS

Thirty-one patients were analyzed. Rechallenge (median 6 cycles [range 1-27], mainly cetuximab [80.7%]), started at a median anti-EGFR-free time of 18.4 months (1.7-37.5 months) after two (38.7%) or more (61.3%) lines of treatment; 64.5% of patients received a full dose. Median OS and PFS were 9.8 months (95% confidence interval [CI] 8.2-11.4) and 2.6 months (95% CI 1.7-3.4), respectively. ORR was 10%, and DCR was 30%. The most common AEs were diarrhea (35.5%), anemia (29%), emesis (6.4%), and neutropenia (6.4%); < 5% grade ≥ 3; 48.4% of patients reported anti-EGFR-related skin toxicity (grade > 1). Hypomagnesemia required supplements in 29% of patients. Dose delays (≥ 3 days) and reduction (≥ 20%) were reported in 11 (35.5%) and seven patients (22.6%), respectively.

CONCLUSIONS

In RAS/BRAF wt mCRC patients, an anti-EGFR rechallenge provides a feasible therapeutic option with clinical benefit (survival) and a manageable safety profile.

Liquid Biopsy for Prognosis and Treatment in Metastatic Colorectal Cancer: Circulating Tumor Cells vs Circulating Tumor DNA

Liquid biopsy recently gained widespread attention as a noninvasive alternative/complementary technique to tissue biopsy in patients with cancer. As technological advances have improved both feasibility and turnaround time, liquid biopsy has expanded tumor molecular analysis with acknowledgement of both spatial and temporal heterogeneity, overcoming many limitations of traditional tissue biopsy. Because of its diagnostic, prognostic, and predictive value, liquid biopsy has been extensively studied also in metastatic colorectal cancer. Indeed, as personalized medicine establishes its role in cancer treatment, genetic biomarkers unveiling the emergence of early resistance are needed. Among the wide variety of tumor analytes amenable to collection, circulating DNA and circulating tumor cells are the most adopted approaches, and both carry clinical relevance in colorectal cancer. However, few studies focused on comparing feasibility between these two approaches. In this review, we discuss the potential implications of liquid biopsy in metastatic colorectal cancer, assessing the advantages and drawbacks of circulating DNA and circulating tumor cells, and highlighting the most relevant trials for clinical practice.