The NEO-RT trial: A phase 3 randomized trial of neoadjuvant chemotherapy, excision and observation versus chemoradiotherapy for early rectal cancer, CCTG CO.32.

Abstract

TPS3646 Background: There is significant interest in organ-sparing management of rectal cancer. Data from the National Cancer Database suggest that in 2020 only 20% of US patients with stage I rectal cancer are managed non-operatively. The phase II CCTG CO.28/NEO trial previously reported high rates of tumor downstaging, organ preservation and excellent rectal function among patients with T1-T3abN0 rectal adenocarcinoma treated with 3 months of FOLFOX/CAPOX followed by Transanal Endoscopic Surgery (TES). The phase III CO.32/NEO-RT trial (NCT06205485) will compare two organ sparing strategies for patients with stage I rectal cancer. Methods: Eligible patients with clinical stage T1/2 N0 adenocarcinoma with preserved mismatch repair (MMR) will be randomized 1:1 to ARM A, 3 months of FOLFOX or CAPOX versus ARM B, chemoradiation (54 Gy) followed by tumor restaging within 16 weeks of start of therapy. Patients with histological high grade, mucinous or deficient MMR and those that can be treated with tumor excision alone are excluded. The primary endpoint is tumor downstaging to clinical Complete Response (cCR) by pelvic MRI, endoscopy and digital rectal exam. Subsequent TES is recommended for all patients with tumor response and may be done within 24 weeks of treatment begin, followed by 5 years (y) of observation with serial MRI (q6m x 2y then annually) and endoscopy (q4m x 2y, then q6m during year 3, then annually). The co-primary endpoint is Quality Of Life (QOL) measured by the Low Anterior Resection Score (LARS). In a non-inferiority comparison between treatment arms, if the cCR is assumed to be 45% in ARM B and if there is no true difference between ARMS A and B, then 250 patients are required to be 80% sure that the upper limit of a one-sided 90% confidence interval will exclude a difference in favor of chemoradiation of more than 14%. Results: The approved CCTG CO.32 trial is expected to open February, 2024 at Canadian CCTG and US Alliance, ECOG-ACRIN, NRG, and SWOG NCTN sites with an estimated accrual duration of 4 years. Conclusions: The results of this study will have a major impact on the treatment of patients with stage I rectal cancer. Both arms offer the potential of organ preservation and results will inform whether induction chemotherapy is non-inferior to ChemoRT and compare patient QOL and functional outcomes. Clinical trial information: NCT06205485 .