A phase 1/2 study of vusolimogene oderparepvec (RP1) in primary melanoma (mel) to reduce the risk of sentinel lymph node (SLN) metastasis.
Authors: Zarka Jabra , Joshi Urvashi Mitbander , Rose Amy , Zang Yan , Kirkwood John M. , Luke Jason J. , Zarour Hassane M. , Davar Diwakar , Najjar Yana G. 
Published: June 2024

TPS9614

Background: The majority of the 80,000 newly diagnosed mel patients in the US have localized early-stage disease and undergo wide local excision (WLE) with or without SLN biopsy. The SLN is a critical prognostic marker and pivotal to immune response initiation, and fosters tumor-mediated immune suppression and pre-metastatic niches. Thus, SLN is a key target for local immune intervention. Vusolimogene oderparepvec (RP1), a locally administered oncolytic immunotherapy, provides a unique opportunity for intervention following mel diagnosis, prior to definitive surgical management. Derived from the HSV1 strain RH018A, RP1 exhibits superior killing on human tumor cell lines, designed with deletions in neurovirulence factors (ICP34.5 and ICP47) and immune-stimulating elements (increased US11 expression, GM-CSF and GALV-GP R-) to maximize oncolytic potency and induce cell death. Preclinical and clinical data demonstrate RP1's robust antitumor efficacy in advanced mel. This trial addresses a crucial gap in understanding RP1's impact on SLN dynamics, holding promise for preventing disease recurrence in this high-risk population. We hypothesize that in mel patients with high risk, clinically node negative disease (pT3b-T4b), administration of RP1 will reduce rates of SLN positivity compared to a historic control by favorably reshaping the immune landscape of the primary tumor, SLN and peripheral blood. Methods: This investigator-initiated, single site, open label, non-randomized phase 1/2 pilot study (NCT06216938) will enroll 25 patients with high-risk, clinically node-negative mel (pT3b-T4b). Major eligibility criteria include diagnosis of pT3b, T4a, or T4b non-uveal mel with visible residual tumor or positive initial biopsy margins, ECOG 0 or 1 and adequate organ function on screening labs. Patients will receive 3 doses (1ml/dose) of RP1, locally injected at the primary tumor site before standard WLE and SLN biopsy (SLNB). The first dose on day 1 will be 10e6 pfu/ml, followed by 10e7 pfu/ml for the next two doses on days 15 and 21, administered over 4-5 weeks before WLE and SLNB. Surgery occurs within 35 days of the 1st RP1 injection to avoid delays in definitive treatment. Biopsies and blood samples are obtained pre- and post-treatment. Patients will be followed for up to 3 years. Safety assessments include physical exams, labs, and adverse events (AE) monitoring. The primary endpoint is the rate of SLN positivity in the overall cohort, calculated by comparing the observed rates to the expected number of positive SLNs for that cohort using the Melanoma Institute of Australia's Prediction Tool. Secondary endpoints include safety and tolerability of RP1, RFS and OS. Exploratory correlative assays will compare the immunophenotype in primary tumor and the SLN (IHC) and in peripheral blood (flow cytometry) between baseline and on treatment. Clinical trial information: NCT06216938 .