Pseudoprogression (Psp) In Patients With Peripheral T-Cell Lymphoma (Ptcl) Treated With The Novel Stapled Peptide Alrn-6924, A Dual Inhibitor Of Mdmx And Mdm2

Background: ALRN-6924, an α-helical stapled p53 peptide, is the first-in-class and only dual inhibitor of MDMX and MDM2 currently in clinical trials for both, solid and hematologic malignancies. In tumors with wild-type (WT) TP53, ALRN-6924 can induce p53-dependent cell cycle arrest and apoptosis and separately can invoke p53-mediated immunomodulatory effects, including but not limited to lymphocyte chemotaxis and diminution of PD-L1 expression on tumor cells. This report begins to describe the biologic underpinnings of PsP in selected PTCL patients (pts) treated with ALRN-6924. Despite imaging-based progressive disease (PD), careful monitoring for clinical benefit in light of conflicting imaging (PsP) results led to the decision to treat beyond radiologic progression and the observation of subsequent, delayed radiologic responses.