Colorectal cancer (CRC) is the third leading cause of mortality worldwide. The Food and Drug Administration recently designated pembrolizumab, an immune checkpoint inhibitor (ICI) against a programmed death-1 receptor, as a breakthrough drug for the treatment of patients with mCRC whose tumors have deficient mismatch-repair gene expression (as evidenced by microsatellite instability-high) and patients with solid tumors with a high tumor mutational burden with ≥10 mutations/megabase. We present a patient with metastatic CRC having renal and adrenal gland metastases. Comprehensive molecular profiling performed on a site of metastatic CRC in the kidney revealed multiple genomic alterations characteristic of CRC and rare chromosome 9p24.1 amplification, resulting in a co-amplification of the PDL1, PDL2, and JAK2 genes. Although this genomic alteration may predict the response to ICI, the lack of pembrolizumab prevented the patient from receiving targeted treatment and succumbing to the disease.

BACKGROUND: Immune checkpoint inhibitors have potential applications in treating various cancers but are associated with immune-related adverse events, such as inflammation, in a wide range of organs; however, allergic inflammation caused by these agents has not been extensively studied.
METHODS: A 65-year-old man was diagnosed with a kidney neuroendocrine carcinoma. Three months after kidney resection surgery, the tumor cells had metastasized to his liver and lymph nodes. Subsequently, the patient started chemotherapy; however, regardless of treatment, the tumor grew, and the patient experienced a series of adverse effects, such as taste disorder, anorexia, and general fatigue. Finally, he was administered a programmed cell death (PD)-1 inhibitor, nivolumab (biweekly, toal 200 mg/body), which was effective against kidney carcinoma. However, the patient had a bronchial asthma attack at 22 cycles of nivolumab treatment and chest computed tomography (CT) revealed an abnormal bilateral shadow after 37 cycles of nivolumab treatment. Bronchoscopy findings revealed eosinophil infiltration in the lungs along with severe alveolar hemorrhage. Paranasal sinus CT scanning indicated sinusitis and nerve conduction analysis indicated a decrease in his right ulnar nerve conduction velocity. Based on these findings, the patient was diagnosed with eosinophilic granulomatosis with polyangiitis; he was treated with prednisolone, which alleviated his bronchial asthma. To restart nivolumab treatment, the dose of prednisolone was gradually tapered, and the patient was administered a monthly dose of mepolizumab and biweekly dose of nivolumab. To date, there have been no bronchial attacks or CT scan abnormalities upon follow up.
CONCLUSIONS: We present a rare case in which a patient with cancer was diagnosed with eosinophilic granulomatosis with polyangiitis following treatment with a PD-1 inhibitor. Blockade of PD-1 and the programmed cell death ligand (PD-L) 1/PD-1 and PD-L2/PD-1 signaling cascade may cause allergic inflammation. Further studies are needed to identify the specific mechanisms underlying allergic inflammation after PD-1 blockade.