Severe colitis after PD-1 blockade with nivolumab in advanced melanoma patients: potential role of Th1-dominant immune response in immune-related adverse events: two case reports

The patient was an 80-year-old man with malignant melanoma of the neck. His medical history included diabetes and ischemic heart disease, but no autoimmune diseases. At diagnosis, his performance status (PS) was 1. The primary tumor was a 2.4-mm-thick lesion with no ulceration, and BRAF mutations were negative. No obvious metastatic lesions were detected clinically. The primary tumor was resected with lymph node dissection, identifying micro-metastasis in one sentinel node. The pathologic stage was IIIB (pT3a, N2a, M0 by TNM classification). He received 5 cycles of adjuvant therapy with interferon beta at a dose of 3-million units per body every 7 weeks. After a 6-month treatment-free period, follow-up computed tomography (CT) revealed a metastatic lesion in the lung. Then, at 1 year after the original diagnosis, nivolumab treatment was started at a dose of 2 mg/kg every 3 weeks. On day 64, after 4 administrations of nivolumab, the patient presented with mild diarrhea. On day 92, upon returning to our institution for the fifth nivolumab administration, he showed intractable diarrhea, a fever of 39 °C, and fatigue. He complained of passing watery and bloody stools more than 12 times per day. Nivolumab was discontinued and he was hospitalized to undergo intensive examinations and treatment. Abdominal CT showed intestinal edema, suggesting severe mucosal inflammation (Fig. 1a). Anti-bacterial treatment was immediately started with ampicillin-sulbactam (6 g/day). The fecal examination showed no signs of infectious bacteria. Colonoscopy revealed ulcerative lesions (full-circumference mucosal defect), especially in the sigmoid colon and more distal segments (Fig. 1B [a]). To assess the microenvironment of those lesions, multiplexed fluorescent immunohistochemistry was conducted in the same way as that performed in our study [8]. Immunohistochemical analysis of the colon biopsy showed severely inflamed mucosa with infiltration of CD8⁺ cells and T-bet expressing CD4⁺ cells (Fig. 1B [c]). T-bet expressed in both CD4⁺ and CD8⁺ cells. Infiltration of GATA3⁺ and RORγt⁺ cells were not obvious (Additional file 1 Figure S1). Based on these findings, administration of corticosteroids (0.5 mg/kg ≒ 30 mg/body) was started with a diagnosis with autoimmune colitis. However, the diarrhea was not fully recovered. One week after corticosteroids administration, the colonoscopy showed ulcerous lesion was improved but remained (Fig. 1B [b]). The colon biopsy samples revealed residual infiltration of CD8⁺ cells (Fig. 1B [d]). In addition, infiltration of Foxp3⁺ cells was more prominent than before corticosteroids administration (Fig. 1B [e] and [f]). On day 106, the corticosteroid dose was increased to 60 mg/body due to the persistent diarrhea, with passage of mucous and bloody stools more than 10 times per day. On day 108, based on the inflammatory laboratory findings having subsided, corticosteroid tapering was started and the antibiotic was stopped. At that time, the disease status was evaluated as a partial response. On day 113, the diarrhea showed gradual improvement, and dietary intake was restarted. By day 134, the corticosteroid dose was decreased to 5 mg/body and the diarrhea showed complete resolution. On day 144, based on overall improvement, we planned to discharge this patient. However, he developed a fever of 40 °C. Blood culture detected Klebsiella pneumonia, suggesting bacterial translocation from the intestines. Sepsis was complicated by disseminated intravascular coagulation and acute respiratory distress syndrome. On day 152, the patient died of multiple organ failure.

The second case was a 58-year-old man with malignant melanoma involving the nail plate of the right middle finger. He had a past history of arrhythmia, but no autoimmune diseases. At the time of diagnosis, the primary lesion was 1.2 mm in thickness and clinically localized. The patient underwent curative surgical treatment. His melanoma harbored no BRAF mutations. The pathologic stage was IB (pT2a, N0, M0 by TNM classification). At 4 years after the initial diagnosis, a follow-up examination detected multiple bone metastases in the spine and ribs. He received radiotherapy for the spinal lesions (30 Gy in 10 fractions). Nivolumab was then started at the same dosing schedule as that used for case 1 (2 mg/kg every 3 weeks). The treatment was initially well tolerated. On day 87, after 4 administrations of nivolumab, the patient complained of watery diarrhea and mild abdominal distension. Abdominal CT showed a thickened intestinal tract, and colonoscopy revealed edematous and inflamed mucosa (Fig. 2A and B [a]). The pathological examination of the colon showed marked infiltration of CD8⁺ cells and T-bet expressing CD4⁺ cells, similar to the findings in case 1 (Fig. 2B [c]). Infiltration of GATA3⁺ and RORγt⁺ cells were not prominent (Additional file 1: Figure S1). Case 2 patient was hospitalized and the nivolumab treatment was temporarily interrupted. In this patient, colitis as an irAE was strongly suspected, prompting immediate administration of corticosteroids (60 mg/body ≒ 1 mg/kg). The fecal examination showed no signs of infectious enteritis. The diarrhea resolved rapidly in response to the corticosteroids and dietary intake was restarted. Colonoscopy findings was also improved a week after corticosteroids administration and we found CD8⁺ and T-bet⁺ cells were reduced from the findings of colon biopsy samples (Fig. 2B [b] and [d]). Infiltration of Foxp3⁺ cells was also reduced after corticosteroid administration (Fig. 2B [e] and [f]). The patient was then discharged and nivolumab was restarted. On day 141, after 6 administrations of nivolumab, he developed a fever of 38 °C. Although he had no signs of either obvious dyspnea or hypoxemia, chest X-ray revealed bilateral pneumonia. He was hospitalized and nivolumab treatment was again interrupted. Chest CT showed consolidation with air bronchograms in the left lower lobes (S8 and S9), and scattered consolidation in the right lower lobes. Bronchoscopic examination detected no apparent abnormalities, including purulent discharge. Pulmonary irAE (pneumonitis) was suspected and a 60 mg/body dose of corticosteroids was started. After 1 week, steroid tapering was initiated (10 mg/body/week to 30 mg, and thereafter 5 mg/body/week until cessation). However, the patient experienced 2 recurrences of pulmonary irAE during the steroid tapering period and was administered 60 mg/body doses of corticosteroids with subsequent amelioration of this condition. After resolution of the pulmonary irAE, the patient was treated with ipilimumab and re-treated with nivolumab. However, the melanoma had continued to progress and the patient died of melanoma progression on day 355.

Stored blood samples were retrospectively examined to analyze for the temporal changes in cytokine levels (Fig. 3). The commercially available cytokine panel (Bio-Plex ProTM Human Cytokine 27-plex Assay; Bio-Rad Laboratories) was used for this analysis in accordance with the manufacturer’s instructions. We found that the serum C-reactive protein (CRP) levels and interleukin-6 (IL-6) levels were decreased after corticosteroid administration in both cases (Fig. 3 and Additional file 2: Table S1). The decrease in CRP and IL-6 was proportionate to the clinical resolution of the colitis.