Effect of Aflibercept Plus Modified FOLFOX6 Induction Chemotherapy Before Standard Chemoradiotherapy and Surgery in Patients With High-Risk Rectal Adenocarcinoma: The GEMCAD 1402 Randomized Clinical Trial.

IMPORTANCE: Preclinical studies suggest that a vascular endothelial growth factor (VEGF) blockade may play a role in the preoperative treatment of rectal adenocarcinoma; however, how to combine anti-VEGF drugs with neoadjuvant chemotherapy (CT) and/or chemoradiotherapy (CRT) remains controversial. OBJECTIVE: To study the effect of aflibercept plus modified fluorouracil, leucovorin, and oxaliplatin (mFOLFOX6) induction CT prior to standard CRT and total mesorectal excision (TME) surgery in patients with high-risk rectal adenocarcinoma. DESIGN, SETTING, AND PARTICIPANTS: In the Grupo Español Multidisciplinar En Cancer Digestivo (GEMCAD) 1402 phase 2 randomized clinical trial, 180 patients aged 18 to 75 years, identified by centrally reviewed magnetic resonance imaging to have mrT3c-d/T4/N2 rectal adenocarcinoma, were enrolled from 20 treatment centers in Spain between January 2015 and March 2017. Patients were randomized in a 2:1 treatment to control arm ratio. The primary end point was evaluated at 2 interim and 1 final analyses. The study was designed to perform hypothesis testing at α = .2 and ß = .2. A 2-sided P value of <.1984 in the final analysis of the intention-to-treat population was the threshold for considering the experimental treatment to be more effective than the control. INTERVENTIONS: Patients received neoadjuvant mFOLFOX6 with (arm A; n = 115) or without (arm B; n = 65) aflibercept, 4 mg/kg (every 2 weeks, 6 cycles, and 3 months) prior to standard CRT and TME surgery. MAIN OUTCOMES AND MEASURES: The primary end point was a pathologic complete response (pCR) (ypT0N0). Secondary end points included toxic effects, surgical morbidity, R0 resections, compliance, and 3-year disease-free survival. RESULTS: For the 115 patients who received treatment with mFOLFOX6 plus aflibercept, the median (range) age was 60 (32-75) years, 77 men (66.9%) and 38 women (33.0%). For the 65 patients who received induction CT treatment with only mFOLFOX6, the median (range) age was 65 (39-75) years, 39 men (60.0%) and 26 women (40.0%). The pCR rate in the intention-to-treat population was 22.6% (95% CI, 15.3%-31.3%) in arm A and 13.8% (95% CI, 6.5%-24.6%) in arm B (P = .15). The main differential toxic effect was grade 3/4 hypertension during the induction phase. Postoperative complications were similar in both arms (15.5% in arm A and 12.9% in arm B). A total of 106 patients (92.1%) in arm A and 63 (96.9%) in arm B received all treatment cycles. CONCLUSIONS AND RELEVANCE: The study met its primary end point. The findings suggest that adding aflibercept to an induction regimen using mFOLFOX6 plays a role in increasing the pCR rate in patients with high-risk rectal adenocarcinoma, without substantially increasing surgical complications. The GEMCAD 1402 trial provides a rationale for phase 3 trials. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02340949.