Pembrolizumab-Induced Herpes Zoster in Metastatic NSCLC: A Case Report

For those navigating the complex landscape of oncology care in Chicago, the intersection of cutting-edge immunotherapy and unexpected side effects can perceive like a daunting maze. Whether you are visiting a specialist near the Illinois Medical District or coordinating care through the sprawling campuses of the city’s top-tier research hospitals, the emergence of new clinical data often changes how patients and families approach their treatment plans. A recent case report highlighting the occurrence of herpes zoster—commonly known as shingles—following chemo-immunotherapy with pembrolizumab in patients with metastatic non-small cell lung cancer (NSCLC) serves as a critical reminder that these powerful medications can trigger reactions that aren’t always intuitive.

The paradox of immune checkpoint inhibitors (ICIs) is that they are designed to “unmask” cancer cells, allowing the body’s own immune system to recognize and attack the tumor. Pembrolizumab, a PD-1 inhibitor, works by strengthening the immune response. Though, this very process of immune activation can lead to complications. In the case of herpes zoster, the reactivation of the varicella-zoster virus (VZV) is the culprit. While we typically associate shingles with a weakened immune system, research suggests a different mechanism at play here. Some experts hypothesize that the immune reconstitution caused by ICIs may actually increase the incidence of herpes zoster, mirroring a phenomenon known as Immune Reconstitution Inflammatory Syndrome (IRIS), which was originally observed in HIV patients receiving antiretroviral therapy.

The Clinical Divergence: PD-1 Inhibitors vs. EGFR Inhibitors

Understanding the risk involves comparing different classes of targeted therapies. Data from retrospective studies, including research conducted at Jichi Medical University Hospital, indicates a significant difference in how patients fare regarding herpes zoster depending on their medication. In a study comparing patients with recurrent or advanced lung cancer, those treated with PD-1/PD-L1 antibodies experienced significantly shorter herpes zoster-free survival compared to those treated with EGFR tyrosine kinase inhibitors. Specifically, the hazard ratio was 0.20 (95% CI: 0.048-0.84; p = 0.016), suggesting that the administration of PD-1/PD-L1 antibodies is independently and significantly associated with the occurrence of the virus.

For patients in Chicago receiving these treatments at institutions like Northwestern Memorial Hospital or University of Chicago Medicine, this means that the vigilance required during immunotherapy differs from that of traditional targeted therapy. While clinicians have long been aware of the potential for autoimmune-like side effects from ICIs—where the immune system attacks healthy tissue—the risk of infectious complications like herpes zoster has not always received the same level of attention. However, as more patients transition to these therapies, the clinical community is being urged to anticipate and monitor for VZV reactivation.

The Role of Immune Reconstitution in Viral Reactivation

The mechanism behind Here’s fascinating, and frightening. Herpes zoster occurs when the varicella-zoster virus, which remains latent in the body after a primary chickenpox infection, reactivates. Traditionally, this happens in the elderly or the immunocompromised. But with ICIs, we are seeing a potential “rebound” effect. As the drug removes the “brakes” from the immune system to fight lung cancer, the resulting inflammatory environment may trigger the virus to wake up. This suggests that the risk is not necessarily due to a lack of immunity, but rather a volatile shift in the immune landscape.

This is particularly relevant for patients with non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). Data shows that the proportions of these patients were higher in ICI groups compared to non-ICI groups, partly because approvals for anti-PD-1 antibodies in SCLC (such as atezolizumab) didn’t occur until 2019 and 2020. As these drugs become standard of care across more cancer types, the likelihood of encountering these “immune-mediated” infections increases. It is a delicate balance: the very mechanism that helps a patient achieve remission from a metastatic tumor can simultaneously open the door for a latent virus to cause significant pain and skin lesions.

Navigating these side effects requires a multidisciplinary approach. If you are managing a diagnosis in the Windy City, it’s important to realize that your oncologist is only one piece of the puzzle. Managing the systemic effects of immunotherapy often requires a bridge between oncology, dermatology, and infectious disease specialists to ensure that the treatment for the cancer doesn’t lead to a secondary crisis that diminishes the patient’s quality of life.

Local Resource Guide for Chicago Residents

Given my background in analyzing medical trends and their local impacts, I know that when a patient in Chicago is hit with a complication like herpes zoster while undergoing pembrolizumab treatment, the “system” can feel overwhelming. You aren’t just fighting cancer; you’re fighting a secondary infection that can cause intense nerve pain. To handle this effectively, you need a specific triad of local professional support.

ICI-Specialized Medical Oncologists

You need a provider who doesn’t just prescribe pembrolizumab but is well-versed in the latest literature regarding immune-related adverse events (irAEs). Seem for oncologists affiliated with NCI-Designated Cancer Centers in the city. When interviewing a provider, ask specifically about their protocol for monitoring viral reactivation in patients on PD-1/PD-L1 inhibitors. They should be proactively discussing VZV risks and potentially discussing vaccination schedules prior to the start of immunotherapy.

Consultative Infectious Disease Specialists

Because the reactivation of VZV in the context of immunotherapy can be atypical, a general practitioner may not be enough. Consider seek an infectious disease specialist who has experience with “non-HIV IRIS” or drug-induced hypersensitivity syndromes. The criteria for hiring here should be their experience in managing antiviral therapies in immunocompromised or “immune-activated” cancer patients, ensuring the antiviral treatment doesn’t interfere with the efficacy of the chemotherapy or immunotherapy.

Neuropathic Pain Management Experts

Herpes zoster is notorious for post-herpetic neuralgia—chronic nerve pain that can persist long after the rash vanishes. In a city with world-class pain clinics, look for specialists who focus on neuropathic pain rather than general pain management. The ideal provider will offer a combination of pharmacological interventions and physical therapies tailored to patients whose systems are already stressed by metastatic cancer treatments.

Dealing with the side effects of advanced cancer treatment is a marathon, not a sprint. Ensuring your care team is integrated—meaning your oncologist is talking to your infectious disease doctor in real-time—is the best way to mitigate the risks associated with these powerful medications.

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