Personalised Oncology Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
Vanessa Wong , Wei Hong , Sumitra Ananda , Catherine Dunn , Rachel Wong , Yat Hang To , Matthew E. Burge , Louise M. Nott , Jeanne Tie , Jeremy David Shapiro , Ross Jennens , Muhammad Adnan Khattak , Aflah Roohullah , Peter Gibbs
Background: BRAFmt is a negative prognostic factor in mCRC but also identifies a patient population that may benefit from BRAF targeted therapy. Results from recent trials (BEACON and SWOG1406) demonstrate improved survival outcomes in second- and third-line settings when combining a BRAF inhibitor, an EGFR inhibitor (EGFRi) +/- a MEK inhibitor. In both trials, irinotecan and cetuximab was the control arm with a dismal response rate of 2-4% and progression free survival (PFS) of only 2 months. This suggests chemotherapy plus an EGFRi may not be the optimal approach where BRAF-targeted therapies are not available or have failed. Methods: Data from July 2009 to September 2021 was analysed from TRACC, a multi-site Australian mCRC comprehensive prospective registry enrolling consecutive patients. Patient characteristics, treatment and survival outcomes were examined for patients treated with chemotherapy (CT) alone, with bevacizumab (BEV) or with an EGFRi. Results: Of 2046 registry patients, 256 (13%) harboured a BRAFmt. 72 BRAFmt patients had received second-line (28%) treatment, including CT alone (n = 28), CT plus BEV (n = 26), and CT plus EGFRi (n = 18). Baseline characteristics are shown in the table. Median second-line PFS was 3.3, 4.7 and 1.8 months, for CT alone, CT plus BEV and CT plus EGFRi respectively. Median overall survival (OS) was 8.7, 7.9 and 2.5 months respectively. In multivariate analysis, PFS when treated with CT plus EGFRi trended inferior to CT alone (p = 0.054) and CT plus BEV (p = 0.061), whereas for OS, treatment with CT plus EGFRi was inferior to CT alone (p = 0.038) and CT plus BEV (p = 0.015). Poor PFS was associated with age ≥ 65 years (HR 3.03, p < 0.001) and ECOG ≥ 2 (HR 2.62, p = 0.004), but not associated with a right side primary (p = 0.17), mismatch repair (MMR) status (p = 0.86), or ≥ 3 organs with metastases (p = 0.32). Poor OS was associated with age ≥ 65 years (HR 3.11, p < 0.001), ECOG ≥ 2 (HR 7.32, p < 0.001), right side primary (HR 3.03, p = 0.002) and proficient MMR status (HR 3.57, p = 0.018), but not associated with ≥ 3 organs with metastases (p = 0.17). Conclusions: Less than one-third of BRAFmt mCRC patients received second-line therapy in a real-world setting, indicating an urgency to explore activity of BRAF targeted therapy in the first line setting. Treated patients received limited benefit, with CT plus EGFRi PFS outcomes comparable to BEACON control arm (1.8 vs 2.0 months) and trending inferior to other options. The best OS outcomes were achieved with CT alone or CT plus BEV.
All treated patients (n = 72) | CT alone (n = 28) | CT plus BEV (n = 26) | CT plus EGFRi (n = 17) | |
---|---|---|---|---|
Age ≥ 65 years | 25 (35%) | 12 (43%) | 9 (35%) | 4 (24%) |
Female (%) | 42 (58%) | 21 (75%) | 18 (69%) | 3 (18%) |
ECOG ≥ 2 (%) | 7 (10%) | 1 (4%) | 2 (8%) | 4 (24%) |
≥ 3 organs with metastases (%) | 19 (26%) | 8 (29%) | 2 (8%) | 9 (53%) |
Right side primary (%) | 49 (68%) | 16 (57%) | 19 (73%) | 12 (71%) |
dMMR status (%) | 8 (11%) | 2 (7%) | 5 (19%) | 1 (6%) |
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