Cytomegalovirus reactivation in patients with refractory checkpoint inhibitor-induced colitis

Enhancement of Cytomegalovirus-Specific Cytokine Production after Modulation of the Costimulation in Kidney Transplant Patients

Kidney transplantation is the therapy of choice for patients with end stage renal disease. Due to immunosuppressive treatment, patients are at risk for opportunistic infections. Cytomegalovirus (CMV) reactivation is highly relevant in kidney transplant recipients because it occurs—depending on the serological constellation of the donor and recipient—in more than half of the patients and influences patient outcome. Patients with CMV reactivation show decreased allograft and overall survival. Previous studies could demonstrate that transplant patients often show weak CMV-specific immunity. Besides immunosuppressive treatment, additional mechanisms may reduce CMV-specific immunocompetence such as enhanced negative costimulation. Hence, the aim of this study was to investigate if the function of CMV-specific cells of kidney transplant recipients could be restored by a modulation of costimulatory molecules. To address this question, lymphocytes of kidney transplant patients were stimulated with CMV-specific antigens and incubated with programmed death-ligand 1 (PD-L1), programmed cell death protein 1 (PD-1), or B- and T-lymphocyte attenuator (BTLA) antibodies. Afterwards, the IFN-γ, IL-21, and IL-17A production was measured by the ELISpot assay. It could be shown that a blockade of the ligand PD-L1 resulted in an increased CMV-specific IFN-γ, IL-21, and IL-17A secretion. The blockade of the receptor PD-1 distinctly enhanced the production of IL-21. BTLA antibodies, however, led only to a marginal increase of CMV-specific IFN-γ and of IL-21 production. Experiments in healthy controls could confirm the results of the kidney transplant recipients. Furthermore, they could demonstrate that treatment with the immunosuppressive drug tacrolimus resulted in decreased CMV-specific IFN-γ and of IL-21 production. Thus, our study could show for the first time that the blockade of the PD-L1/PD-1 pathway also modulates CMV-specific Th21 and Th17 cell function in kidney transplant recipients. Further studies are mandatory to clarify the role of Th21 and Th17 cells in CMV control of these patients.

Enterocolitis due to immune checkpoint inhibitors: a systematic review

Immune checkpoint inhibitors targeting cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) and programmed death-1 (PD-1)/ligand are increasingly used to treat several types of cancer. These drugs enhance antitumour T-cell activity and therefore induce immune-related adverse effects (irAE), of which gastrointestinal (GI) irAE are among the most frequent and severe. This systematic literature review summarises the clinical manifestations, management and pathophysiology of GI irAE due to immune checkpoint inhibitors. GI irAE induced by anti-CTLA-4 are frequent, potentially severe and resemble IBD, whereas those induced by PD-1 blockade seem to be less frequent and clinically more diverse. Baseline symbiotic gut microbiota is associated with an enhanced antitumour response to immune checkpoint inhibitors and an increased susceptibility to developing enterocolitis, in patients treated with anti-CTLA-4. These findings open new perspectives for possible manipulation of the gut microbiota in order to better identify responders to immune checkpoint inhibitors and to increase their efficacy and safety.

Anti-Inflammatory Biologics and Anti-Tumoral Immune Therapies-Associated Colitis: A Focused Review of Literature

An increasing number of drugs including monoclonal antibodies and small molecules, either anti-inflammatory or immunity-enhancing, have been developed to treat human diseases and the number of medications in these classes is likely to expand in the future. The two most commonly used categories of such therapies are the anti-inflammatory group (anti- tumor necrosis factor (TNF) α, anti-interleukins/interleukin receptors, and anti-integrin bodies) and the anti-tumoral agents (immune checkpoint inhibitors, anti-CD20, and anti-endothelial growth factor). Although the anti-inflammatory biologics have brought about a revolutionary effect in the management of a variety of autoimmune disorders including rheumatologic diseases, inflammatory bowel disease, and inflammatory dermatological diseases, their ability to induce colitis in patients without a prior history of colitis or exacerbate quiescent colitis has been increasingly and unexpectedly recognized. While the use of immune-augmenting monoclonal antibody therapies results in a significant survival benefit in a subset of patients with malignancies, these monoclonal antibodies also have the ability to cause colitis through an apparent autoimmune mechanism. Colitis associated with these medications may demonstrate multiple histologic patterns including increased apoptosis (graft versus host disease (GVHD)-like), autoimmune enteropathy pattern, acute colitis pattern, ischemic colitis, inflammatory bowel disease pattern, either ulcerative colitis-like, Crohn's disease-like, or fulminant colitis-like. In addition, anti-inflammatory biologics are known to cause or reactivate latent infections such as tuberculosis and increase the risk for malignancies including high-grade lymphomas as well as indolent lymphoproliferative disorders. Thus, the differential diagnosis for colitis in patients receiving therapeutic anti-inflammatory biologics or anti-tumoral agents can be broad. Optimal diagnosis and treatment requires a multidisciplinary approach. This review aims to provide an overview of the literature on the clinical features, histology, and treatment of these newly recognized anti-inflammatory biologic and anti-tumoral immune therapy-induced colitises and hopes this outlines will raise the vigilance of all clinicians of these entities.