Abstract PS14-05: Phase 1/2 clinical trial of a topical submicron particle paclitaxel (SOR007) for the treatment of cutaneous metastases

Background: Cutaneous Metastases (CM) are an infrequent presentation of advanced solid tumors and are usually associated with symptoms of pain, pruritus, and secondary infections, all of which negatively affect quality of life and result in additional morbidity. Systemic chemotherapy, advanced wound care, topical agents, cryo-, electro-, photodynamic-, laser and intralesional therapies have been limited by inconsistent efficacy, inconvenience, or toxicity. In this open-label phase 1/2 clinical trial, submicron particle paclitaxel in an anhydrous base (SOR007) was evaluated for topical treatment of CM from breast cancer (n=21), leiomyosarcoma (n=1) and Paget’s disease (n=1). Previously, in vitro, in vivo, and clinical studies demonstrated penetration of paclitaxel into the dermis with the silicone-based anhydrous producing subtoxic plasma levels in GLP toxicology studies and early clinical trials. Trial Design: The phase 1/2 open label trial evaluated 3 doses of SOR007 (0.15%, 1.0%, 2.0%). Approximately 0.5 grams (1 FTU) of SOR007 per 50 cm2 treatment area was applied BID during a 3+3 dose-rising phase for 28 days (n=10) or a dose-expansion phase at 2% strength BID for 28 days (n=2) or 56 days (n=11) unless discontinuation became necessary due to clinical course of the underlying disease. Results: At least one eligible lesion was treated per subject and classified per RECIST 1.1. In the 28-day application group, 10 subjects were treated and in the 56-day application group, 11 subjects were treated. Lesion response is summarized in the table below for data to date. Lesion response was evaluated within 2 weeks of last treatment day in most subjects. Conclusions: SOR007 was safe when applied to CM lesions. SOR007 resulted in decreased lesion progression or reduced lesion area in the majority of CM subjects. These clinical benefits became more consistent and pronounced at 2% strength with longer treatment suggesting a dose/duration response. Lesion pain reduction is also suggested from the study. Additional clinical research with more subjects and longer treatment periods is in the early planning stage. Citation Format: Mario E Lacouture, Julie E Lang, Sant Chawla, Shari Goldfarb, Alina Markova, Alexander Pan, Rose Marie Cavanna-Mast, Peter Mast, Christopher Savoie, Gere diZerega. Phase 1/2 clinical trial of a topical submicron particle paclitaxel (SOR007) for the treatment of cutaneous metastases [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS14-05.