Immunotherapy (Toripalimab) for Reducing Recurrence Risk After Surgery for Mismatch Repair Deficient Stage IIB, IIC, or III Colon Cancer

PRIMARY OBJECTIVE:

I. Evaluate the efficacy of adjuvant toripalimab in patients with resected stage IIB, IIC, and III mismatch repair deficient (dMMR) colon cancer by measuring 3-year disease-free survival.

SECONDARY OBJECTIVES:

I. Define the immune related toxicity profile of toripalimab in the adjuvant setting.

II. Further evaluate the efficacy of adjuvant toripalimab specifically by measuring 3-year relapse free survival (RFS), 5-year disease free survival (DFS), and 5-year overall survival.

TERTIARY/EXPLORATORY OBJECTIVES:

I. To explore immune, ctDNA, and omic markers associated with clinical efficacy (DFS).

II. To assess patient reported outcomes (PRO) and health related quality of life (QoL).

OUTLINE:

Eligible consenting participants will receive toripalimab intravenously every 3 weeks for 6 months (8 doses) in the absence of disease recurrence or unacceptable toxicity. After completion of study treatment, patients are followed up every 6 months until 5 years post-resection. After completion of study medication, participants undergo surveillance follow up with blood tests, computed tomography (CT) scans, colonoscopy at specified intervals until 5 years post-resection. Patient reported outcomes and quality of life will also be assessed with questionnaires.