[Anti-PD1 immunotherapy followed by tuberculosis infection or reactivation]

INTRODUCTION

Immunotherapy is now a standard of care in oncology. There is a need to improve our knowledge about immune-related adverse events, especially infectious diseases.

CASE REPORT

We describe the case of a 49-year old male who received anti-PD1 therapy, to treat metastatic melanoma with pulmonary metastasis. After 3 cycles of nivolumab, computed tomography scanning showed a decrease of the pulmonary metastasis in the upper left lobe, but revealed new pulmonary lesions such as tree-in-bud and a lung cavity in the same lobe. This was diagnosed as pulmonary tuberculosis with no antibiotic resistance identified. The patient continued the immunotherapy and was initiated onto a standard anti-tuberculosis therapy. In the absence of an initial positive IFN-γ release assay (Quantiferon) test, but as there might have been a history of primary infection during childhood, a reactivation of tuberculosis was considered to be likely.

CONCLUSIONS

This is the ninth case of tuberculosis infection under immunotherapy and it underlines the need to consider infection risks in patients undergoing immunotherapy. An INF-γ release assay screening test should be considered an essential part of the pre-treatment work-up.

[An unusual digestive complication under anti-PD-1 (pembrolizumab)]

The most commonly reported pattern of anti-PD-1 induced colitis is an active colitis characterized by neutrophilic inflammation and prominent apoptosis. On the other hand, reports of collagenous colitis (which is a microscopic colitis) are exceptional. In this report, we describe an unusual case of anti-PD1-associated collagenous colitis in a 76-year-old man, treated with pembrolizumab for a stage IV cutaneous melanoma. Fourteen months after the start of pembrolizumab, the patient developed a grade 3 diarrhea (up to 9 stools per day) associated with profound hypokalemia. No bacterial, viral or parasitological infectious agents were found from stool analysis. The rectosigmoidoscopy showed colonic diffuse congestion with no ulceration. Systematic biopsies were performed during endoscopy. Histologically, the fragments analyzed revealed a moderately thickened subepithelial collagen layer (20-30μm thick) associated with a mild mixed inflammatory infiltrate within the lamina propria. There were no granuloma lesions, ulcerations or viral inclusion bodies. The patient was initially successfully treated with corticosteroids (prednisone) and temporary interruption of pembrolizumab. However, during corticosteroids tapering, a relapse was observed. The treatment was switched to budesonide, leading to a complete and definitive resolution of diarrhea. To date, budesonide has been stopped and pembrolizumab has not been restarted. Currently, there is a bone progression treated by radiotherapy alone. In case of a more important progression, a systemic treatment will be secondarily discussed.