Dual Autoimmune Disorders Uncovered in Gastric Cancer Patient on Nivolumab

Background on Gastric Cancer Treatment

A 59-year-old man diagnosed with recurrent gastric cancer recently presented an intriguing medical case that showcases the rare coincidence of two autoimmune disorders: rheumatoid arthritis and Sjögren's syndrome. This condition arose while receiving nivolumab, a third-line treatment aimed at boosting the immune system against cancer.

Patient's Medical Journey

The patient's medical history began with his gastric cancer diagnosis, which came without any prior indications of autoimmune diseases within his personal or family background. Initially, he underwent a laparoscopic distal gastrectomy along with a systematic D2 lymph node dissection, which categorized his cancer at pathological stage IIIA (T3N2M0).

Following surgery, an adjuvant chemotherapy regimen combining S-1 and oxaliplatin was administered over six months. Although the treatment was initially successful, six months later, a surge in carcinoembryonic antigen (CEA) levels indicated disease progression, leading to new treatment strategies involving various chemotherapy combinations to manage his recurrent cancer.

Emergence of Autoimmune Conditions

Upon initiation of nivolumab, the patient was symptom-free and showed no signs of autoimmune issues. However, after just two courses, he began experiencing arthralgia in the proximal interphalangeal joints, which was classified as Grade 1 inflammatory arthritis. Although treated temporarily with loxoprofen, symptoms increased in frequency and intensity after subsequent doses of nivolumab, leading to additional joint pain and morning stiffness.

These worsening symptoms necessitated urgent assessment by a rheumatologist, revealing active swelling and tenderness in multiple joints. Initial tests for typical autoimmune markers indicated notable abnormalities, prompting further testing.

Confirming the Diagnosis

Comprehensive serological evaluations confirmed the presence of significant autoimmune responses. The patient tested positive for elevated rheumatoid factor and anti-cyclic citrullinated peptide antibodies, both strong indicators of rheumatoid arthritis. Additionally, tests revealed positivity for anti-SS-A antibodies, suggesting Sjögren's syndrome, supported by clinical signs of dry eyes.

His symptoms met the diagnostic criteria for both rheumatoid arthritis and Sjögren's syndrome, constituting a remarkable dual diagnosis that is rarely seen in clinical practice.

Treatment Strategies

To manage the autoimmune conditions, the medical team initiated treatment with oral prednisolone and methotrexate. However, the appearance of a small pleural effusion following the introduction of methotrexate forced a change in medication. Instead, iguratimod was prescribed, and the patient's symptoms stabilized without further complications.

As joint symptoms improved, oncologists followed treatment closely. With a notable reduction in the size of the umbilical port nodule, additional immunotherapy with nivolumab was resumed after controlling the autoimmune responses. Despite managing the arthritis effectively, complications arose, prompting the ultimate cessation of nivolumab treatment due to an unrelated pulmonary infection.

Conclusion and Implications

This case illustrates the rare phenomenon of simultaneous autoimmune disorders triggered by checkpoint inhibitors such as nivolumab. While immune-related arthritis is acknowledged among cancer patients receiving immunotherapy, the joint presentation of rheumatoid arthritis and Sjögren's syndrome presents unique clinical complexities. Further exploration of these cases may provide valuable insights into the mechanisms linking immunotherapy and autoimmune disorders, which can improve management strategies for similar patients in the future.