Figure 1a Figure 1b

Positron emission tomography, diagnosis; blue arrows show increased uptake of 18F-Fluorodeoxyglucose in the peritoneal surface, prominently in the pelvis and in the pericapsular area of the liver periphery, SUVmax: 9.0 (F1a), 10 months later, no pathological involvement was detected (F1b).

The patient underwent 2 cycles of intravenous chemotherapy with cisplatin and pemetrexed (Pemetrexed 500 mg/m2/day in each cycle on days 1 and 21, Cisplatin 75 mg/m²/day on days 1 and day 21 in each cycle, totally 6 cycles were given). After 2 cycles of IV chemotherapy, CRS and HIPEC with cisplatin were applied in purpose of local disease control and to prevent relapse. Follow-up was done with serial abdominal magnetic resonance imaging, they showed regression in the disease findings. Because of a positive for Programmed Death Ligand 1 status, we started nivolumab at the 5th month of the chemotherapy. Nivolumab treatment was given as 3 mg/kg/dose, every 2 weeks by IV infusion over 1 hour. No disease activity was detected in the PET/CT imaging performed 10 months after the diagnosis.

At the time of diagnosis and in the follow up, hepatic transaminase level elevation (Grade1-2, CTCAE v5) observed in laboratory examinations. In the 4th month of nivolumab, an increase in serum creatinine value (Grade2, CTCAE v5) and hypertension (Grade3, CTCAE v5) were detected. Considering the nephrotoxic effect of nivolumab, the drug dose was reduced by 25%. After nivolumab dose reduction, kidney functions, blood pressure monitoring and urine output turned back to normal.

The patient was administered 32 courses of nivolumab without disease relapse. The patient had been progression free for 20 months.