Colorectal Cancer (MSI-H)

This phase II clinical trial evaluates the efficacy and safety of three neoadjuvant regimens in patients with locally advanced microsatellite instability-high/mismatch repair-deficient (MSI-H/dMMR) colorectal cancer (CRC): 1) Regimen A: Dual immune checkpoint blockade with nivolumab plus ipilimumab. 2) Regimen B: Nivolumab plus radiotherapy. 3) Regimen C: Nivolumab monotherapy. The primary objectives are to determine whether: 1) Dual immune checkpoint blockade (Regimen A) is superior to nivolumab monotherapy (Regimen C); and 2) Immunotherapy plus radiotherapy (Regimen B) is superior to nivolumab monotherapy (Regimen C). Methods: Participants will be randomized in a 1:1:1 ratio to one of the three arms. For patients with resectable tumors, surgical resection will be performed. In patients with low rectal cancer and poor prospects for sphincter preservation, a watch-and-wait (WW) strategy is an option if a clinical complete response (CR) is achieved following neoadjuvant therapy.

Colorectal cancer is a major public health issue. In France, in 2015, there were 40,000 new cases and 17,000 deaths. It develops from adenomas or scalloped polyps, which are usually accessible for endoscopic resection. Piece-meal mucosectomy is the standard technique in Europe and the USA for lesions larger than 2 cm. It has certain advantages, such as its ease of learning, low morbidity and speed of execution. However, it has one major disadvantage, namely the low rate of monobloc resection and R0 for lesions larger than 2 cm. Submucosal dissection (SMD) has become the standard technique for endoscopic resection of superficial colorectal lesions larger than 2 cm, particularly if the lesion presents a risk of superficial degeneration. Unlike mucosectomy, this technique allows for monobloc resection targeting R0 for all types of superficial lesions without size limitations, enabling histological analysis without data loss and with a recurrence rate of less than 2%. However, there are numerous disadvantages to dissection: * SMD is more difficult than mucosectomy, with a long learning curve, limiting its use to expert centres. * The morbidity of dissection is higher than that of mucosectomy, with a risk of perforation of 4% vs. 1%. * The procedure takes on average three times longer than mucosectomy. From a technical standpoint, various methods have been described to facilitate the procedure, in particular traction using clips and elastic bands, which is the most widely used method in France. Micro-Tech offers a new traction device, SureTrac, which is designed to perform single or multi-polar traction and to adjust the intensity of traction during dissection. The product is CE marked but has not yet been distributed in France. No data are currently available in the literature on this product other than a case report submitted for publication. A pilot study conducted by an expert centre is therefore necessary. This is why this study is being initiated.

This is a Phase 1/2, multi-center, open-label, dose-escalation and expansion study to evaluate safety and tolerability, PK, pharmacodynamic, and early signal of anti-tumor activity of MDNA11 alone or in combination with a checkpoint inhibitor in patients with advanced solid tumors.