The Best Upfront Regimen for Unresectable CRC Liver Mets?

What is the best upfront chemotherapy option for patients with colorectal cancer (CRC) and unresectable liver metastases?

A new report demonstrated why patients benefit most from starting on a two-drug chemotherapy regimen — FOLFOX or FOLFIRI — instead of a three-drug regimen — FOLFOXIRI.

The CAIRO5 trial compared overall survival among 294 patients with right sided tumors and/or RAS/BRAF mutations who received FOLFOXIRI (5-fluorouracil (FU), oxaliplatin, irinotecan, plus folinic acid as an enhancer) or investigators’ choice of FOLFOX (5-FU, oxaliplatin, and folinic acid) or FOLFIRI (5-FU, irinotecan, and folinic acid). All patients also received bevacizumab.

In a post hoc analysis, researchers found no overall survival benefit among patients receiving the three-drug regimen. At a median follow-up of just over 5 years, the median overall survival was 23.6 months with FOLFOX or FOLFIRI vs 24.1 months with FOLFOXIRI (P = .44).

The finding means that patients can avoid the extra toxicity associated with combining oxaliplatin and irinotecan without compromising overall survival, Alan P. Venook, MD, a gastrointestinal medical oncologist at the University of California San Francisco, told Medscape Medical News.

The analysis did not stop there in defining the optimal upfront therapy for this patient population.

In a second arm of the analysis, researchers looked at whether swapping in panitumumab for bevacizumab offered any benefit in 236 patients with left-sided tumors and wild-type RAS/BRAF who received either of the two-drug regimens.

Here, the authors also found no benefit of using panitumumab with FOLFOX or FOLFIRI instead of bevacizumab, reporting a median overall survival of 38.3 months with panitumumab vs 39.9 months with bevacizumab.

In addition to avoiding upfront FOLFOXIRI, patients can also avoid the skin reactions and other toxicities associated with panitumumab, including “horrible acne,” Venook said.

Overall, the results support the use of FOLFOX or FOLFIRI with bevacizumab “irrespective of RAS/BRAFV600E status and tumor sidedness” as the initial treatment for CRC with liver-only metastases, concluded the study investigators, from the University Medical Center Utrecht, in Utrecht, the Netherlands.

Why Does This Clarity Matter?

The study confirms the standard practice in the United States of starting patients on a two-drug chemotherapy with bevacizumab for the indication and highlights “why we don’t go all in right at the beginning” with a three-drug regimen, Venook said.

In short, more drugs upfront isn’t going to change patients’ long-term survival outcome. Plus, using FOLFOXIRI upfront means “you’ve really pretty much used up all your guns for early treatment,” Venook said.

As for bevacizumab vs panitumumab, most practitioners in the United States favor bevacizumab because of the rash many patients on epidermal growth factor receptor blockers like panitumumab and cetuximab get, Venook said.

Because FOLFOX and FOLFIRI are equally effective on the overall survival front, the decision between them comes down to a balance between patient comorbidities and side effect profiles. Neuropathy, for instance, is more common with FOLFOX, whereas diarrhea is more likely with FOLFIRI, Venook said.

Venook favors FOLFIRI because “almost every patient will develop neuropathy” after seven or eight doses of FOLFOX, which limits its use. “You’re expecting that first treatment to give you the most mileage,” so starting with a treatment “you’re going to get limited use out of…never made sense to me,” he said.

Venook noted that the results apply only to the older patients studied in CAIRO5 and not necessarily to the ever-growing population of younger people with CRC. Patients in the trial had a median age of 62 years with a performance status of 0-1, a median of 12 liver lesions with no metastases outside the liver, and no contraindications to local or systemic treatment.

The CAIRO5 analysis also looked at what happens after upfront chemotherapy, with the goal being to shrink liver lesions so the lesions can be surgically removed or treated with thermal ablation.

Almost half the patients ultimately underwent resection or ablation, and 39% of those in the FOLFOX or FOLFIRI plus bevacizumab group and 49% in the FOLFOX or FOLFIRI plus panitumumab group then went on to receive adjuvant chemotherapy (ACT) to reduce the risk for recurrence. ACT was recommended in the study, but not required, and consisted of chemotherapy minus bevacizumab or panitumumab.

Overall survival was longest among patients who had complete local treatment without recurrences for at least 6 months (64.3 months) or who had salvage local treatment after early recurrence (58.9 months). Median overall survival was 30.5 months for patients with complete local treatment without salvage after early recurrence, and 28.7 months for patients with incomplete local treatment. Overall survival was worst in patients who remained unresectable (18.3 months).

ACT was associated with improved overall and relapse-free survival, justifying discussing the option with patients who have completed local treatment, the study team said.

CAIRO5 was funded by Roche and Amgen, makers of bevacizumab and panitumumab, respectively. Bond and Venook didn’t have any disclosures.

M. Alexander Otto is a physician assistant with a master’s degree in medical science and a journalism degree from Newhouse. He is an award-winning medical journalist who worked for several major news outlets before joining Medscape Medical News. Otto is also an MIT Knight Science Journalism fellow. Email: [email protected]