SUMMARY: ColoRectal Cancer (CRC) is the third most common cancer diagnosed in both men and women in the United States. The American Cancer Society estimates that approximately 151,030 new cases of CRC will be diagnosed in the United States in 2022 and about 52,580 patients are expected to die of the disease. The lifetime risk of developing CRC is about 1 in 23.
Approximately 15-25% of the patients with CRC present with metastatic disease at the time of diagnosis (synchronous metastases) and 50-60% of the patients with CRC will develop metastatic disease during the course of their illness. First line treatment of metastatic CRC include Oxaliplatin or Irinotecan, in combination with a Fluoropyrimidine and Leucovorin (FOLFOX or FOLFIRI), along with a VEGF targeting agent such as Bevacizumab. Patients with stage IV colorectal cancer are now routinely analyzed for extended RAS and BRAF mutations. KRAS mutations are predictive of resistance to EGFR targeted therapy. Approximately 8-15% of all metastatic CRC tumors present with BRAF V600E mutations and BRAF V600E is recognized as a marker of poor prognosis in this patient group. These patients tend to have aggressive disease and do not respond as well to standard treatment intervention. Approximately 20% of the BRAF-mutated population in the metastatic setting has MSI-High tumors, but MSI-High status does not confer protection to this patient group. Colorectal cancer patients with unresectable liver-only metastases at the time of initial presentation may potentially be cured, after downsizing of metastases by neoadjuvant systemic therapy. However, the optimal neoadjuvant induction regimen has not been defined.
CAIRO5 is a prospective, randomized, multicentre, Phase III trial, conducted to investigate the optimal systemic induction therapy for patients with initially unresectable, liver-only colorectal cancer metastases. In this study, 294 patients were randomized to receive either FOLFOX or FOLFIRI plus Bevacizumab (N=148), or FOLFOXIRI plus Bevacizumab (N=146) for up to 12 cycles. Bevacizumab was given at a dose of 5 mg/kg IV. FOLFOX/FOLFIRI regimen consisted of either Oxaliplatin 85 mg/m2 IV or Irinotecan 180 mg/m2 IV, given along with Leucovorin 400 mg/m2 IV over 120 minutes, 5-Flourouracil (5-FU) 400 mg/m2 IV, followed by 5-FU 2400 mg/m2 given as an IV infusion over 46 hours. FOLFOXIRI regimen consisted of Oxaliplatin 85 mg/m2 IV, Irinotecan 165 mg/m2 IV, given along with Leucovorin 400 mg/m2 IV over 120 minutes, followed by 5-FU 3200 mg/m2 given as an IV infusion over 46 hours. Treatment was given every 2 weeks for a maximum of 12 cycles, followed by 5-FU, Leucovorin and Bevacizumab maintenance until disease progression. Enrolled patients had metastatic CRC with previously untreated liver-only metastases, (un)resectability status was prospectively assessed by a central panel consisting of radiologists and liver surgeons, according to predefined criteria, and patients were assessed for resectability every 2 months. Eligible patients had right-sided primary tumor and/or RAS or BRAF V600E mutated tumor. Both treatment groups were well balanced. The median age was 63 years, 41% had right-sided primary tumor, 86% of tumors had RAS mutation, 7% had BRAF V600E mutation, 5% had prior adjuvant chemotherapy, the median number of colorectal liver metastases was 12, and 87% had potentially resectable colorectal metastases. Patients were stratified by potentially resectable versus permanently unresectable colorectal liver metastases, BRAFV600E mutation, sidedness and choice of Irinotecan versus Oxaliplatin. The Primary endpoint was Progression Free Survival (PFS). Secondary endpoints included R0/1 resection, Overall Survival (OS), Overall Response Rate (ORR), toxicity, pathologic response and postoperative morbidity.
At a median follow up of 41 months, the median PFS was 9.0 months with doublet regimen FOLFOX/FOLFIRI plus Bevacizumab versus 10.6 months with the triplet regimen of FOLFOXIRI plus Bevacizumab. (HR=0.74; P=0.02). The ORR was 32% in the FOLFOX/FOLFIRI plus Bevacizumab group versus 52.1% in the FOLFOXIRI plus Bevacizumab group (P<0.001), R0/1 resection/ ablation rates were 37.4% versus 51.4% (P=0.02), and postoperative complications occurred in 38.2% versus 51.2% (P=0.14), respectively. Overall Survival data was immature at the time of data cutoff. Grade 3 or more adverse events, including neutropenia and diarrhea, were more common in the FOLFOXIRI plus Bevacizumab group.
It was concluded that in patients with initially unresectable colorectal cancer liver metastasis and right-sided and/or RAS or BRAF-mutated primary tumor, the triplet regimen of FOLFOXIRI plus Bevacizumab resulted in superior Progression Free Survival, a higher Objective Response Rate, and a greater chance for R0/R1 hepatic metastasectomy with or without ablation, compared to doublet chemotherapy with FOLFOX or FOLFIRI plus Bevacizumab. This benefit with the triplet regimen was achieved at the cost of increased toxicity, suggesting that careful patient selection should be made for the triplet regimen.
FOLFOXIRI + bevacizumab versus FOLFOX/FOLFIRI + bevacizumab in patients with initially unresectable colorectal liver metastases (CRLM) and right-sided and/or RAS/BRAFV600E-mutated primary tumor: Phase III CAIRO5 study of the Dutch Colorectal Cancer Group. Punt CJA, Bond MJG, Bolhuis K, et al. J Clin Oncol. 2022;40(suppl 17):LBA3506.