From the Research
Cemiplimab (Libtayo) can potentially cause the symptoms described, though they would be considered uncommon or rare side effects, and immediate medical evaluation is necessary if they occur. Cemiplimab is an immune checkpoint inhibitor used to treat certain cancers, and it can sometimes cause immune-related adverse events that affect the nervous system. Involuntary urination, leg weakness, confusion, and loss of balance occurring on the same day as administration could represent a neurological immune-related adverse event or an infusion reaction. These symptoms might indicate conditions like immune-mediated encephalitis, myelitis, or a severe infusion reaction.
Key Considerations
- The most recent and highest quality study, 1, analyzed immune-related adverse events for seven FDA-approved immune checkpoint inhibitors, including cemiplimab, and found that 'respiratory, thoracic and mediastinal disorders' and 'gastrointestinal disorders' were the two most common groups of disorders caused by these inhibitors.
- However, the study also noted that tissue and organ toxicities of ICIs are age and sex specific, with risks of respiratory and urinary system toxicity in male patients and reproductive system toxicity in female patients treated with the ICIs studied.
- Another study, 2, reported a case of a patient with metastatic cervical cancer who achieved a complete response to cemiplimab but experienced severe immune-related adverse events, including cardiovascular toxicity and hypertransaminasemia, which required discontinuation of the medication.
- A real-world study, 3, found that cemiplimab was effective in treating locally advanced and metastatic cutaneous squamous cell carcinoma, with an overall response rate of 58% and a disease control rate of 71.7%, but also noted that some patients experienced treatment-related adverse events, including grade 3-4 adverse events and fatal adverse events.
Recommendations
- Anyone experiencing symptoms such as involuntary urination, leg weakness, confusion, and loss of balance after receiving cemiplimab should contact their healthcare provider immediately or go to an emergency room.
- The treatment team may need to temporarily or permanently discontinue cemiplimab and might prescribe corticosteroids to manage the immune-related inflammation.
- The timing of symptom onset (same day as administration) suggests a possible relationship to the medication, though other causes should also be considered during medical evaluation.