Intralesional Sclerosant for in Transit and Cutaneous Melanoma Metastases

Many patients with metastatic melanoma have in transit and other cutaneous metastases. Untreated, these lesions become eroded, haemorrhagic and symptomatic. When systemic therapy is not warranted, has failed or is not tolerated for in transit disease, and when surgery is not feasible or appropriate, other local treatments are needed. Current options include isolated limb infusion for bulky limb disease, topical immunotherapy with contact sensitisers and imiqiuimod for superficial, nonbulky disease or radiation therapy. Intralesional (IL) agents such as Rose Bengal (PV-10, Provectus) and Talimogene laherparepvec (T-Vec, Amgen) have been used for patients with limited numbers of cutaneous metastases with reported overall response rates of 51% and 26% respectively. It is thought that these IL agents can incite regional or even systemic anti-tumour immune responses, thus providing benefit beyond the individual injected lesions. Use of PV-10, which is not an intrinsic immune modulator, was associated with regression of untreated bystander lesions in 27% of patients. T-Vec is not currently available as a subsidised product in Australia and PV-10 is not currently accessible outside of dual-agent systemic/IL clinical trials. Intralesional injection of the antimetabolites 5-fluorouracil and methotrexate has been used successfully for the treatment of cutaneous squamous cell carcinoma, but the efficacy of these agents in melanoma is unknown. Importantly, the investigator's in transit melanoma patients usually have multiple, often very numerous lesions, making IL injection with adequate volumes of antimetabolites difficult without significant risk of systemic haematologic, hepatic and renal side effects. Hence there is currently an urgent need for tolerable, low cost and accessible intralesional therapies for in transit and cutaneous melanoma metastases. This study aims to evaluate the efficacy and tolerability of intralesional therapy with the sclerosant polidocanol for treatment of in transit and cutaneously metastatic melanoma unsuitable for other therapies. Intravascularly injected sclerosants have a long history of safe and effective use in the treatment of varicose veins. Sclerosants have also been used intralesionally for the treatment of cutaneous lesions such as squamous cell carcinoma, pyogenic granulomas, Kaposi sarcoma and angiomas. They are inexpensive, readily accessible and can be easily administered in the clinic to multiple metastases. By inciting cell death within melanoma metastases in the skin, they may also incite anti-tumour immune responses in untreated bystander lesions, as is observed with IL PV-10 therapy.