Immune-mediated thyroiditis, immune-mediated cytopenia and lack of efficacy: case reportA 71-year-old man exhibited lack of efficacy during treatment with carboplatin, etoposide, paclitaxel and gemcitabine for metastatic ileocaecal mixed neuroendocrine non-neuroendocrine neoplasm (MINEN) and squamous non-small-cell lung cancer (SQ-NSCLC). He also developed immune-mediated grade 3 thyroiditis and grade 3 cytopenia during treatment with pembrolizumab for SQ-NSCLC [routes, dosages and duration of treatment to reactions onset not stated].The man was heavy smoker (116 pack years), with a past medical history of stage 1 chronic obstructive pulmonary disease (COPD). He presented to the emergency room after experiencing diffuse abdominal pain for 2 weeks. He was admitted for further evaluation. In following days, he presented worsening of intestinal obstruction symptoms for which he underwent an emergency resection with an emergency right hemicolectomy. After surgery, biopsy sampling was performed with a diagnostic bronchoscopy and body PET-scan. The body PET-scan showed hepatic lesions and para-aortic mediastinal lymphadenopathies. Histopathological results of the biopsy sampling obtained from resected colonic mass were consistent with ileocaecal MINEN with component of moderately differentiated colorectal adenocarcinoma and poorly differentiated small cell neuroendocrine carcinoma. Histopathology of the lung mass obtained for bronchoscopy biopsies revealed a lesion, which corresponded to squamous cell carcinoma (SQ-NSCLC). He was referred to the medical oncology for further consultancy. He started receiving palliative chemotherapy with carboplatin and etoposide, which was mainly directed towards NEC component of the MiNEN, in view of rapid progression at the hepatic level. Resolution of hepatic lesions was achieved through radiologic control after two cycles and no recurrence was observed at the colonic level; however, tumor progression was notable at the pulmonary mass. For optimization of treatment of SQ-NSCLC along with consideration of digestive MINEN, his chemotherapeutic regimen was switched to carboplatin and paclitaxel. Consequently, stability of SQ-NSCLC was achieved after three cycles; however, it progressed later with increase in size and metabolic activity at the lung mass. Therefore, second-line monotherapy treatment with pembrolizumab was initiated, which was directed to the SQ-NSCLC. He developed immune-mediated toxicities in form of grade 3 thyroiditis and grade 3 cytopenia [reaction outcomes not stated]. The occurrence of immune-mediated toxicities was attributed to pembrolizumab treatment.The immunotherapy with pembrolizumab was discontinued after one cycle and the man started receiving third-line chemotherapy with carboplatin and gemcitabine. However, he developed tumour progression at the CNS level, for which he received palliative holocraneal radiotherapy treatment, along with his ongoing chemotherapy. He eventually died due to disease progression at 11 months after the primary diagnosis of MINEN.