Cutaneous Toxicities of PI3K Inhibitors: A Series of Two Cases and Review of the Literature

Phosphoinositide 3-kinase (PI3K) inhibitors are a class of antineoplastic agents currently approved for the treatment of multiple hematologic malignancies and breast cancer. These medications have specific molecular targets to limit toxicity; however, cutaneous adverse effects are frequently reported and can require cessation of therapy. Morbilliform, eczematous, psoriasiform, and pityriasis rubra pilaris-like eruptions are most common, though exfoliative dermatitis and Stevens-Johnson syndrome/toxic epidermal necrolysis have also been reported. We highlight two cases of photo-accentuated skin reactions to duvelisib, a p110-δ and p110-γ isoform inhibitor. Both cases required oral corticosteroids and interruption of therapy for definitive management due to severity. While one patient was able to tolerate re-challenge with duvelisib and continue on therapy, both patients experienced recurrence of cutaneous eruptions with repeat exposure, establishing a notable temporal correlation. Thus, these cases contribute a novel presentation of adverse reactions to PI3K inhibitors to existing literature.