Should a patient with active shingles proceed with their next Keytruda (pembrolizumab) infusion for renal cell carcinoma?

Management of Keytruda (Pembrolizumab) Treatment During Active Shingles Infection

Keytruda treatment should be temporarily delayed until the shingles outbreak has resolved to avoid potential complications and worsening of the infection.

Rationale for Delaying Immunotherapy

Immune checkpoint inhibitors like pembrolizumab (Keytruda) can affect the immune system's ability to manage infections. When a patient has an active shingles (herpes zoster) infection, several important considerations apply:

• Immune checkpoint inhibitors can potentially exacerbate viral infections by altering immune responses
• Treating the shingles infection should take priority to prevent complications such as post-herpetic neuralgia
• Continuing immunotherapy during active infection could theoretically worsen the infection or lead to disseminated disease

Clinical Decision Algorithm

1. Temporarily withhold Keytruda

   • Delay the scheduled infusion until the shingles outbreak has completely resolved
   • This approach prioritizes infection management while minimizing risk of complications

2. Treat the shingles infection aggressively

   • Initiate antiviral therapy (acyclovir, valacyclovir, or famciclovir)
   • Provide appropriate pain management
   • Monitor for complications of shingles

3. Resume Keytruda treatment after resolution

   • Once shingles lesions have completely crusted over
   • When the patient is no longer considered infectious
   • When antiviral therapy course is completed

Supporting Evidence

The NCCN guidelines for immune checkpoint inhibitor administration emphasize careful monitoring for potential adverse events and complications 1. While the guidelines don't specifically address shingles infections, they highlight that "close monitoring of potentially lethal immune-related adverse events (irAEs) in patients receiving immune checkpoint inhibitors is essential."

The NCCN guidelines for Small Cell Lung Cancer (which can be extrapolated to other cancers treated with immunotherapy) note that "immunotherapeutic agents, such as nivolumab and pembrolizumab, may cause unique immune-mediated adverse events that are not seen with traditional cytotoxic chemotherapy" 1. This supports a cautious approach when managing patients with active infections.

Important Considerations

• Risk of worsening infection: Immunotherapy could potentially complicate the management of active viral infections
• Treatment efficacy: A brief delay in immunotherapy is unlikely to significantly impact overall cancer treatment efficacy
• Patient safety: Prioritizing the resolution of the active infection before continuing immunotherapy reduces the risk of complications

After Shingles Resolution

Once the shingles infection has resolved completely:

• Resume regular Keytruda treatment schedule
• Consider antiviral prophylaxis if the patient has had recurrent herpes zoster infections
• Monitor closely for any signs of recurrent infection or immune-related adverse events

This approach balances the need for continued cancer treatment while ensuring patient safety during an active infection.