Mohandas K. Mallath, MD, Vivek S. Radhakrishnan, DM Tata Medical Center, Kolkata, West Bengal, India
Introduction: Immunotherapy is very effective in patients with micro-satellite instability (MSI-H) or mismatch repair deficient (dMMR) metastatic colorectal cancer (mCRC). We report the case of MSI-H mCRC with poor performance status treated with Immunotherapy for a short duration.
Case Description/Methods: SK a 74 years old male, came to us with complaints of rectal bleeding, spurious diarrhea, weight loss and profound weakness. A sigmoidoscopy revealed an obstructing tumor in the rectum. Biopsy confirmed the diagnosis of a poorly differentiated adenocarcinoma. A CECT scan revealed the tumor was adherent to urinary bladder and there were multiple metastatic lymph nodes in the pelvis, groin and para aortic region. Molecular studies using next-gene sequencing showed MSI-H tumor with no mutations in KRAS, NRAS and BRAF and 46 other genes. He was deemed unfit for palliative surgery, palliative radiotherapy or combination chemotherapy due to his age and poor performance status. A plan to treat him with single agent chemotherapy and place a colonic stent if he developed symptomatic obstruction was made. At the time he was diagnosed, multiple immunotherapy trials including a first line trial comparing Pembrolizumab monotherapy versus combination chemotherapy was under evaluation for patients with MSI-H mCRC. A shared decision was made to use first line immunotherapy. He received six doses of Nivolumab 200 mg every 3 weeks (Q3W) from June to September 2019. A MRI scan in September 2019 showed partial response. After the seventh dose he discontinued the immunotherapy due to financial toxicity. He was later treated with a reduced dose capecitabine monotherapy (1000 mg twice daily X 14 days, every 4 weeks). He has remained progression free for 24 months, and at last evaluation was pain free and performing all activities of daily living without assistance.
Discussion: Current chemotherapy combinations plus biologics are generally not useable in the elderly patients or in those with poor performance status due to toxicity. The final results of the Keynote-177 trial showed doubling of the median progression-free survival with pembrolizumab monotherapy in first line setting. Our case suggest that immunotherapy could benefit patients with microsatellite unstable mCRC having poor performance status even when used for a limited period.
Disclosures:
Mohandas Mallath: DR Reddy's Laborotories – Advisory Committee/Board Member, Grant/Research Support. Johnson and Johnson – Advisory Committee/Board Member, Consultant. Rosche – Speaker's Bureau.
Mohandas K. Mallath, MD, Vivek S. Radhakrishnan, DM. P0186 - Prolonged Progression Free Survival of a Senior With Metastatic Rectal Cancer and Poor Performance Status and First-Line Immunotherapy, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.
