INNOVA: Interval or neoadjuvant chemotherapy in rectal cancer—A phase II randomized study comparing interval versus neoadjuvant chemotherapy in magnetic resonance imaging-defined high-risk rectal cancer.

Abstract

91 Background: Total neoadjuvant treatment is a promising option in rectal cancer. We aim to compare neoadjuvant versus interval chemotherapy in high risk rectal cancer to identify the optimal sequencing of treatment. Methods: Using a Simon two-stage design, newly diagnosed MRI defined high risk rectal cancer patients were randomly assigned in a 1:1 ratio to receive three 21 day cycles of chemotherapy with Capecitabine 1000 mg/m2 and Oxaliplatin 130 mg/m2 either before (Arm A-neoadjuvant) or after (Arm B-interval) chemoradiation followed by surgery. Primary end point was the pathological complete response (pCR) following surgery. A heirarchial model was used to assess the primary and secondary end points (toxicity and compliance) and compare the two regimens. (Clinical Trial Registry of India No. CTRI/2015/01/005385). Results: In this single centre study conducted between November 2015 and February 2020, 42 patients were randomised in the first stage. A pCR was seen in 4 patients in Arm A and 6 in Arm B. Hence another 52 patients were randomised in the second stage of which an additional 3 and 2 patients had a pCR leading to an overall pCR of 7 and 8 patients (15.5% vs 17% and 18.4% vs 19.5% in the intent-to-treat and per-protocol populations in Arm A and B respectively. This exceeded the minimum predetermined number of 5 pCR needed to qualify for further evaluation for each arm. Grade ≥3 toxicity was observed in 2.2% of 132 cycles and 4.6% of 129 cycles of chemotherapy delivered in 45 and 43 patients in Arm A and B respectively while 11/43 (25.5%) and 10/47 (21.2%) patients experienced grade ≥3 toxicity during chemoradiation. Treatment break of > 7 days was seen in 23.2% and 29.7% of patients in Arm A and B respectively while 93.3% in Arm A and 100% of patients in Arm B completed all 3 planned cycles of pre-operative chemotherapy. A non-significant trend towards greater pathological downstaging was seen in Arm B than in Arm A (ypT1-2 39% vs 26.3%; p = 0.1 and ypN0 68.3% vs 57.9%; p = 0.5 respectively). Conclusions: In this phase two study, both neoadjuvant and interval chemotherapy emerged eligible for further evaluation against the standard of care in a future phase III study. Although we could not pick one winner based on pCR, toxicity or compliance, the greater downstaging observed with interval chemotherapy suggests it could play a greater role in an organ preservation approach. Clinical trial information:CTRI/2015/01/005385, UTN no: U111111650578.