An explorary analysis of a COVID-truncated REPLATINUM phase 3 trial in SCLC.

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e20594 Background: RRx-001 is a small molecule immunotherapeutic in Phase 3 for the treatment of SCLC that is associated with M2-M1 tumor associated macrophage (TAM) repolarization with CD47 downregulation, vascular normalization and reversal of chemoresistance. In a controlled, multicenter clinical trial called REPLATINUM that was prematurely halted due to COVID-19, data from 17 patients with third line or beyond SCLC was analyzed. Moving forward, REPLATINUM(restarted) has added SARS-CoV-2 exclusion criteria. Our aim was to explore the efficacy of RRx-001 in REPLATINUM and to assess the statistical assumptions of the REPLATINUM(restarted) trial in order to inform future clinical development in SCLC. Methods: Patients in REPLATINUM were randomized to receive 1 of 2 arms: 1) carboplatin AUC 5 IV on day 1 or cisplatin 60 mg/m2 IV on day 1 plus etoposide 100 mg/m2 IV on days 1 through 3 every 21 days for up to 4 cycles or 2) 4 mg of RRx-001 administered sequentially with 4 cycles of a platinum doublet (cisplatin or carboplatin plus etoposide as outlined above). Progression Free Survival (PFS) was the primary efficacy endpoint based on a blinded independent central review (BICR). Results: The trial was suspended prematurely after 17 patients had been enrolled due to widespread COVID-19 exposure with the plan to restart the trial. The decision to restart the trial has provided an opportunity to examine the data for preliminary evidence of treatment efficacy. At the time that the REPLATINUM trial was halted, there were 11 patients enrolled on the control arm and 6 on the investigational arm. The BICR assessed median PFS was approximately 7.1 months for RRx-001 + platinum doublet and 3.5 months for the platinum doublet alone based on the truncated database. The BICR assessed PFS hazard ratio was approximately 0.5. OS medians were approximately 8.2 and 6.3 months for RRx-001 + platinum doublet and platinum doublet alone, respectively. Additionally, patients on the RRx-001 + platinum doublet-treated experimental arm experienced less toxicity than patients on the platinum doublet-treated control arm. Conclusions: Despite the small sample size, preliminary results from REPLATINUM suggest a trend toward a favorable primary outcome and improved safety in RRx-001-treated patients and support the validity of the statistical assumptions that underlie the REPLATINUM(restarted) trial. Pivotal evidence will emerge from REPLATINUM(restarted), which is imminently recommencing. Clinical trial information: NCT03699956.