We present a case of a patient with advanced cutaneous SCC who developed severe CMV gastritis after receiving cemiplimab, an anti-PD-1 antibody, and T-VEC oncolytic virus therapy.
While CMV infection in individuals with a healthy immune system often shows no symptoms or appears like a viral or mononucleosis-type illness [6, 7], it can also manifest in the gastrointestinal, neurological, hematological, skin, cardiac, or ocular regions, primarily as a reactivation [7, 8]. CMV gastritis is an uncommon and frequently overlooked condition, typically seen alongside widespread CMV infection. The frequency of CMV infections in the upper digestive system remains undefined [9].
The development of invasive CMV disease in a host like our patient was an unexpected event, given that ICIs work by enhancing T-cell immunity, which is vital for anti-viral protection. The precise rate at which CMV reactivates in patients undergoing ICI treatment remains unclear but is believed to be minimal. Tay et al. [3] noted a mere 0.3% overall occurrence of CMV detection in those administered ICIs. In a vast majority of cases, invasive CMV disease in patients with solid malignancies on ICIs complicated irAEs that required high-dose corticosteroids and other immunomodulatory drugs [3, 10–20], which could be explained by the fact that CMV has tropism to inflamed tissues. Consequently, there's a significant occurrence of CMV infection among patients with severe acute inflammatory bowel disease (IBD), and the frequency is even higher in those with steroid-resistant conditions. [21]
Interestingly, our patient developed invasive CMV disease without pre-existing inflammation in the form of irAE-gastritis, which is typically treated with high doses of corticosteroids. Furthermore, there was no concurrent H. pylori infection or a history of current immunosuppression, as reported in the literature. [3, 4, 10–20, 22] However, our patient complained of dyspepsia for 6 months halfway through his cemiplimab therapy course, which may have represented an unrecognized form of irAE-gastritis before he was diagnosed with CMV.
While the histologic features of ICI-related colitis have been widely reported, there is less data on the upper gastrointestinal (GI) manifestations of irAE. The morphological spectrum of ICI therapy-associated gastritis typically involves diffuse chronic active gastritis, characterized by increased intraepithelial lymphocytes and prominent apoptosis. However, in a subset of patients, it can present as a focal enhancing gastritis with granulomatous inflammation, reminiscent of the gastric involvement seen in Crohn’s disease. [23] In another study, 39% of patients were also found to have gastric peri-glandular inflammation. [24] While our patient’s upper GI biopsies did not show features typically associated with ICI-associated irAE-gastritis, the classic morphology of invasive CMV infection was present. Symptom improvement with antiviral therapy without steroids also supported the infectious process.
Cases of CMV reactivation in patients on ICIs and not previously treated with immunosuppressants are rare [4, 25–27]. In three of those cases [4, 25, 26], CMV gastritis developed without definitive evidence of pre-existing irAE-gastritis, like in our patient, but all patients received either pembrolizumab or atezolizumab and not cemiplimab.
Another aspect of our case that has not been previously described in conjunction with CMV infection is T-VEC therapy. T-VEC is a live attenuated genetically modified HSV designed for replication in tumor cells and local expression of granulocyte-macrophage colony-stimulating factor (GM-CSF) by the infected tumor cells, which is proposed to enhance tumor antigen presentation to the immune system, inducing immune responses to the tumors, but the exact mechanism of action is not known. [28–30] At present, T-VEC stands as the sole FDA-approved viral therapy for melanoma [31, 32]. Nonetheless, it has demonstrated efficacy both as a standalone treatment and when combined with other therapies for cancers other than melanoma. [33–39] According to the official FDA report, the most common treatment-emergent adverse events (≥ 25%) included fatigue, chills, pyrexia, nausea, influenza-like illness, and injection site pain. Local and systemic infections following T-VEC injection have been reported, but the exact incidence is unknown. In one study, 12/52 (23%) patients had any microbiologically confirmed infection identified following T-VEC therapy: 6 were bacterial (3 urinary tract infection, 1 bloodstream, 2 wound), and 9 were viral (5 respiratory, 3 GI, 1 localized HSV infection with dermal lesions more than one year after the final T-VEC). [40] A disseminated herpes infection following T-VEC injection has been reported followed by prolonged melanoma control without further therapy. [41] Upon review of the literature and the results of 23 ongoing T-VEC trials, only one case of invasive CMV disease (colitis) was found in a patient who had received T-VEC, but in combination with ipilimumab, and no further details were available. [42] Our patient had already been experiencing dyspepsia for 5 months prior to T-VEC therapy but reported significant symptom worsening shortly after receiving the oncolytic viral treatment. The role of T-VEC therapy in this context, although utilizing a CMV promoter, seems unlikely to be the direct culprit behind the CMV gastritis because the CMV promoter does not carry genes responsible for infectivity and latency. [29] However, it is theoretically possible that the use of T-VEC might have triggered an immune reaction to CMV in the stomach, potentially resembling an abscopal phenomenon. This phenomenon refers to tumor regression in both the targeted lesion and any untreated tumors at a distant site, which can be caused by local radiation therapy, with or without systemic immunotherapy. [43, 44] The complex interplay between T-VEC, ICIs, and the immune system is still unknown and merits further investigation.
To our knowledge, this is the first reported case of CMV gastritis in a patient treated with both cemiplimab and T-VEC. While CMV reactivation in patients not previously exposed to immunosuppressants is infrequent, the manifestation in our subject was particularly intriguing given the absence of an inflammatory pattern typically associated with such cases. This report heightens awareness of the potential complications associated with ICI treatments and T-VEC. As the medical community ventures deeper into the realm of immunotherapies, both local and systemic, it is important to understand the mechanism of infectious complications, identify potential biomarkers or risk factors associated with the development of those complications and establish proper surveillance.