A phase I trial of plinabulin in combination with nivolumab and ipilimumab in patients with relapsed small cell lung cancer (SCLC): Big Ten Cancer Research Consortium (BTCRC-LUN17-127) study.
Authors: Malhotra Jyoti , Hanna Nasser H. , Chiappori Alberto , Feldman Lawrence Eric , Fujioka Naomi , Rybkin Igor I. , Jalal Shadia Ibrahim , Patel Malini , Moore Dirk , Chen Chunxia , Jabbour Salma K. 
Published: June 2021

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Background: Plinabulin (BPI-2358) is a vascular disrupting agent with immune-enhancing function by inducing dendritic cell maturation and decreasing regulatory T cells. Preclinical studies report that plinabulin potentiates the cytotoxicity of dual checkpoint inhibition (CPI) with nivolumab and ipilimumab. Plinabulin may also reduce immune-related AEs from CPI through its phosphodiesterase-4 (PDE4) inhibitory activity which is associated with anti-inflammatory effects. We report initial results from a Phase I study assessing plinabulin in combination with nivolumab and ipilimumab. Methods: In this dose-escalation phase I study, patients with extensive-stage SCLC who had progressed on or after prior platinum-based chemotherapy (±CPI) were enrolled using a 3+3 design. The primary objective was to determine dose-limiting toxicities (DLT’s) and recommended Phase 2 dose (RP2D). Patients received nivolumab (1 mg/kg), ipilimumab (3 mg/kg) and plinabulin (as per dose escalation schema) IV on day 1 of each 21 day cycles. After completion of 4 cycles, patients continued therapy with nivolumab (240 mg) and plinabulin every 2 weeks till progression or intolerable toxicity. Patients were evaluable for DLT if they received at least 2 cycles of therapy; DLT period was defined as the first 6 weeks from C1D1. Secondary endpoints were ORR, PFS and frequency of irAEs. Correlative analysis included inflammatory biomarkers: hsCRP, ESR, SAA and haptoglobin. Results: Between 9/2018 and 11/2020, 17 patients were enrolled (1 patient withdrew consent before treatment, 16 were evaluable for safety). Median age was 59 years (range 43 to 78); 9 patients were male and 10 had received prior CPI. Eight patients were treated at dose-level 1 of plinabulin (20 mg/m2) and 8 patients at 30 mg/m2 of plinabulin (level 2); dose-level 2 was determined to be RP2D. There were 2 DLTs; 1 at dose-level 1 (grade 3 altered mental status lasting < 24 hours) and 1 at dose-level 2 (grade 3 infusion reaction). The most common treatment-related AEs (all grades) were nausea (10; 63%), infusion reaction (8; 50%), vomiting (7; 44%), diarrhea (7; 44%) and fatigue (6, 32%). Seven patients (44%) had at least one grade 3 or higher treatment-related AE; there were no treatment-related deaths. Two patients (13%) had grade 3 or higher irAE requiring steroids (1 colitis, 1 transaminitis); both at dose-level 1. At data cutoff (12/30/20), there were 3 PRs in CPI naïve patients (3/6; 50%) and 2 PRs in evaluable CPI-resistant patients (2/7; 29%). In the two CPI-resistant patients with confirmed response, the tumor reduction was 68% and 52%. Conclusions: Plinabulin in combination with nivolumab and ipilimumab was safe and well tolerated. A phase 2 study in CPI-experienced patients with relapsed SCLC is planned to confirm the preliminary signals of clinical activity and reduced immune toxicity. Clinical trial information: NCT03575793.