Gastrointestinal toxicity of systemic oncology immunotherapy

Systemic anti-cancer immunotherapy provides a substantial progress in options of current oncology treatment. Yet, this therapeutic approach is potentially associated with a significant gastrointestinal toxicity.

The purpose of this paper is to provide a comprehensive review on pathogenesis, clinical features, dia gnostics and therapy of these toxicities. Review of current knowledge: Check-point inhibitors brought a major progress in anti-cancer immunotherapy and improved significantly prognosis of several malignancies (e. g. metastatic malignant melanoma, non-small-cell lung cancer, gastric and colorectal cancers in high-risk population associated with presence of pathogenic mutations, renal cell carcinoma, squamous cell carcinoma of the head and neck and urothelial carcinoma). They include monoclonal antibodies targeting cytotoxic T lymphocyte-associated antigen 4 (CTLA4; e. g. ipilimumab, tremelimumab), programmed death-1 receptor (PD-1; e. g. pembrolizumab, nivolumab) and its ligand PD-L1 (e. gatezolizumab, avelumab). Chimeric antigen receptor (CAR) T-cell therapy is another new option for haematological malignancies and metastatic colorectal cancer. Major symptoms of gastrointestinal toxicity caused by systemic immunotherapy include diarrhoea (20-50%), entero-colitis (1-10%) and laboratory or clinical signs of hepatopathy (~10%). Anti-cancer immunotherapy can be also complicated by infections (Clostridium difficile, Mycoplasma and/ or cytomegalovirus). There is no data on other possible complications so far. However, it can be assumed that these will also include bile acid malabsorption as well as small intestinal bacterial overgrowth syndrome. Treatment of gastrointestinal complications of immunotherapy should be graded according to their severity. It includes symptomatic medications (e. g. loperamide), systemic glucocorticoids and anti-TNF monoclonal antibodies (alone or together with mycofenolate mofetil or tacrolimus in the most severe cases).

Awareness of possible complications of systemic anti-cancer immunotherapy is crucial for patients safety. It is mandatory to consider immune-related adverse events, complicating infections, bile acids malabsorption and small intestinal bacterial overgrowth syndrome. Prompt proper dia gnostics and immediate vigorous therapy infl uence the outcome of patients signifi cantly. A strictly individualized approach is indispensable.