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PD-1/PDL-1 Inhibitor Use and Development of Keratoacanthomas or Cutaneous Squamous Cell Carcinoma


Pharmacovigilance analysis found significant signals between PD-1/PDL-1 inhibitors and keratoacanthomas as well as cutaneous squamous cell carcinoma, although this finding can not be used to establish causality.

Clinical Pearls

  • This database analysis aimed to determine if any associations existed between PD-1 or PDL-1 inhibitors and keratoacanthomas or cutaneous squamous cell carcinoma using the FDA’s Adverse Events Reporting System  

  • Of the 158,000 reports of PD-1/PDL-1 inhibitor use, there were 43 patients who developed keratoacanthomas and 83 who developed cutaneous squamous cell carcinoma  

  • Pharmacovigilance analysis found significant signals between PD-1/PDL-1 inhibitors and keratoacanthomas as well as cutaneous squamous cell carcinoma, although this finding can not be used to establish causality. 


Discussion:

In this research letter published in JAMA Dermatology, Aggarwal and colleagues aimed to investigate if use of PD-1/PDL-1 inhibitors is associated with development of keratoacanthoma or cutaneous squamous cell carcinoma (cSCC). Using the Federal Drug Administration (FDA) – Adverse Event Reporting System (FAERS), the authors searched for all reported developments of keratoacanthoma or cSCC in PD-1/PDL-1 treated patients. Importantly, the authors performed pharmacovigilance identification via disproportionality analysis, not allowing one to establish causality from their results.


Among 158,000 patients found using or having had used PD-1/PDL-1 inhibitors, 43 patients developed keratoacanthomas and 83 developed cSCC. Although the authors were limited by less data on withdrawal of PD-1/PDL-1, they were able to find that in 10 reports of PD1/PDL-1 associated keratoacanthoma, all 10 keratoacanthomas resolved after discontinuation or dose reduction. Additionally, in 17 reports of PD-1/PDL-1 associated cSCC, 10 cSCC’s resolved after discontinuation or dose reduction. Interestingly, there was one report of keratoacanthoma development following readministration of a PD1/PDL-1 inhibitor.


Overall, this data is valuable in that it shows how PD1/PDL-1 inhibitors may be associated with development of these cutaneous tumors. However, readers should keep in mind this study does not establish a causal relationship between the two and larger scale studies are required. 

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