S102 POLATUZUMAB VEDOTIN (POLA) + OBINUTUZUMAB (G) AND LENALIDOMIDE (LEN) IN PATIENTS (PTS) WITH RELAPSED/REFRACTORY (R/R) FOLLICULAR LYMPHOMA (FL): INTERIM ANALYSIS OF A PHASE IB/II TRIAL
Authors: P. Abrisqueta, B. Kahl, L. Banerjee, A. McMillan, R. Ramchandren, F. Miall, J. Briones, R. Cordoba, E. Gonzalez‐Barca, C. Panizo, J. Hirata, N. Chang, L. Musick, C. Diefenbach
Journal: HemaSphere (2019)

Background: Pola‐G‐Len has the potential to enhance anti‐tumor immune response in R/R FL. Here, we report a pre‐planned interim analysis of a phase Ib/II study (NCT02600897) of Pola‐G‐Len in pts with R/R FL. Aims: To assess the safety and efficacy of induction and maintenance with Pola‐G‐Len in pts with R/R FL. Methods: This is an ongoing, open‐label, multicenter study of pts with R/R FL (excluding grade [Gr] 3b) who have received ≥1 prior anti‐CD20 antibody‐containing chemo‐immunotherapy regimen. The study comprises an initial 3+3 dose‐escalation (DE) phase (to determine the recommended phase II dose [RP2D] of both Pola and Len for the Pola‐G‐Len regimen) followed by an expansion phase to assess the RP2D of Pola and Len. Pts received induction treatment with 6x 28‐day (D) cycles (C) of: G 1000 mg IV (C1: D1, D8, D15; C2‐6: D1); Pola 1.4 mg/kg or 1.8 mg/kg (DE) or RP2D (expansion) IV (D1); and Len 10–20 mg (DE) or RP2D (expansion) PO (D1‐21). Pts with complete response (CR)/partial response (PR)/stable disease (SD) at the end of induction (EOI) received G 1000 mg (D1 every 2mo, for 24mo), and Len (10 mg, D1‐21 monthly, 12mo). Primary endpoints were C1 dose‐limiting toxicities (DLTs), safety/tolerability, CR rate at EOI (modified Lugano criteria). Results: At the interim data cut‐off (6 July 2018), 52 pts were enrolled: 9 discontinued the study (adverse events [AE], n = 3; death due to PD, n = 4; pt withdrawal, n = 1; other, n = 1). At baseline, the median pt age was 62 (range 32–87) years; 60% were male; 58% had FLIPI Gr 3–5; 79% had received ≥2 prior therapy lines; 50% were refractory to their last treatment; 17% had bulky disease (≥7 cm). Two DLTs were reported in the cohort receiving Pola 1.8 mg/kg + Len 10 mg during the DE period (Gr 4 lipase/amylase elevation; asymptomatic, resolved with supportive care; Gr 3 thrombocytopenia leading to a delay in the initiation of cycle 2). Therefore, Pola 1.4 mg/kg + Len 20 mg was selected as the RP2D for expansion. Gr ≥3 AEs were experienced by 75% of pts: neutropenia (46%), thrombocytopenia (17%), anemia (12%) and infections (12%) were the most common AEs. AEs leading to Len dose reduction or interruption occurred in 31% and 52% of pts, respectively. One Gr 5 AE was reported (septic shock after PD in pt receiving subsequent therapy). The RP2D was determined as Pola 1.4 mg/kg + Len 20 mg. Preliminary efficacy data suggest high activity, with an independent review committee‐assessed Modified Lugano response rate of 89% and a CR rate of 67% (Table). Median progression‐free survival was not reached (median follow‐up duration 8.95 mo in the efficacy‐evaluable population). image Summary/Conclusion: The safety profile of Pola‐G‐Len is consistent with known profiles of the individual drugs. Response rates at EOI with Pola‐G‐Len are promising, with high CR compared with available R/R FL treatments.