Safety, Tolerability, and Mechanism of Duvelisib

Zinzani and Brammer turn to the safety profile and mechanism of duvelisib, addressing concerns that have historically accompanied PI3K inhibition. Zinzani notes that contemporary management has improved markedly, with reduced rates of colitis, transaminitis, and pulmonary toxicity, few high-grade events, and a generally manageable profile aided by the induction-then-reduction dosing strategy. Brammer explains the mechanistic basis for duvelisib's distinctive activity, describing it as an inhibitor of both the delta and gamma isoforms of PI3K. He notes that delta inhibition acts on tumor growth and proliferation, while gamma inhibition disrupts the immunosuppressive tumor microenvironment, an effect especially relevant in T-follicular helper disease, where the malignant cells are themselves immune cells prone to autoimmune-type manifestations. The experts acknowledge that this microenvironmental activity can occasionally drive cutaneous and gastrointestinal toxicities, but emphasize that with clear guidance on steroids and dose reductions, most patients can be maintained on therapy.