A Study of Dostarlimab in Participants With Untreated Locally Advanced Rectal Cancer in China

A Phase 2, Single-Arm, Open-Label Study With Dostarlimab Monotherapy in Participants With Untreated Stage II/III dMMR/MSI-H Locally Advanced Rectal Cancer in China

The main goal of this study is to evaluate the effect of dostarlimab monotherapy in Chinese participants with locally advanced Mismatch-repair deficient (dMMR)/ Microsatellite instability-high (MSI-H) rectal cancer who have received no prior treatment.

Inclusion Criteria:

• Participant has histologically confirmed Stage II to III (T3-T4, N0, or T any, N+), locally advanced rectal adenocarcinoma
• Participant has radiologically and endoscopically evaluable disease
• Participant has a tumor which can be categorized as dMMR or MSI-H by central assessment

Exclusion Criteria:

• Participant has distant metastatic disease
• Participant has received prior radiation therapy, systemic therapy, or surgery for management of rectal cancer
• Has a known additional malignancy that progressed or required active treatment within the past 2 years
• Has an active autoimmune disease that has required systemic treatment in the past 2 years
• Has experienced any of the following with prior immunotherapy: any irAE ≥ Grade 3, immune-related severe neurologic events of any-grade (e.g., myasthenic syndrome/myasthenia gravis, encephalitis, Guillain Barré Syndrome, or transverse myelitis), exfoliative dermatitis of any grade [SJS (Stevens-Johnson Syndrome, TEN (Toxic Epidermal Necrolysis), DRESS (Drug rash with eosinophilia and systemic symptoms)], or myocarditis of any grade. Non-clinically significant laboratory abnormalities are not exclusionary
• Has any history of interstitial lung disease or pneumonitis
• Has received or plans to receive an organ or stem cell transplant that uses donor stem cells (allogeneic stem cell transplant)
• Has a history of severe allergic and/or anaphylactic reactions to chimeric, human, or humanized antibodies, fusion proteins, or known allergies to dostarlimab, or its excipients