A phase II single arm feasibility trial of neoadjuvant chemotherapy (NAC) with oxaliplatin/fluorouracil (OxMdG) then short-course preoperative radiotherapy (SCPRT) then immediate surgery in operable rectal cancer (ORC): COPERNICUS (NCT01263171)

Background: Feasibility was assessed of giving NAC prior to SCPRT then immediate surgery in ORC at high risk of metastatic relapse. Methods: Patients (pts) had non-metastatic rectal adenocarcinoma. Pre-treatment pelvic MRI showed resection margin was not at risk (disease > 1mm from mesorectal fascia) but adverse risk factors were present (disease > T3b or node positive or extramural vascular invasion). Pts received 4x2-weekly cycles of oxaliplatin 85mg/m² + levofolinic acid 175 mg, fluorouracil (FU) 400 mg/m² (bolus), then FU 2400 mg/m² (continuous IV in 46 hr). Within 14 days pts had pelvic SCPRT to 25 Gy in 5 daily fractions. Definitive surgery then occurred within a week. Post surgery pts received 16 weeks of OxMdG or oxaliplatin/capecitabine. The primary endpoint was the proportion of pts completing protocol treatment including surgery. Results: 60 UK pts were recruited May 2012-June 2014. At baseline: male 44 (73%), median age 63 (IQR: 56.5-70), WHO PS 0/1 55/5. On pre-treatment MRI tumour was T2/3x/3a/3b/3c/3d/4 in 2/2/16/24/12/1/3 and N0/1/2 in 7/40/13 pts. All pts commenced OxMdG with 57(95%) receiving all 4 cycles. 20 pts (33%) needed a dose reduction and 22 (37%) a dose delay. 58 pts commenced SCPRT (all received full dose) and 57 underwent surgery: anterior resection in 43 (75%), abdominoperineal resection in 11 (19%), Hartmanns in 3 (5%). Three pts withdrew prior to surgery: one lost to follow up after SCPRT, one pt choice and one due to cardiospasm during NAC. Median gap between OxMdG and starting SCPRT was 10 days (IQR: 5-15) and between completing SCPRT and surgery 10 days (IQR: 5-13). Postoperative histology was T0/1/2/3a/3b/3c/4a in 7/3/19/8/9/10/1 pts, N0/1/2 in 39/13/5 pts and ypT0ypN0 in 7/57 pts (12%). All 57 resected pts had a clear (R0) resection margin with no 30 day postoperative mortality. Conclusions: This is the first trial to report on giving NAC prior to SCPRT then surgery within a short time interval in ORC, which proved feasible with good compliance and promising efficacy. The UK NCRI intend to include a similar regimen in a future phase III trial. Clinical trial information: NCT01263171.