1112P - Intralesional therapy with talimogene laherparepvec for stage IIIB-IVM1a melanoma is able to achieve a high rate of complete and durable responses and is associated with tumour load

Background

Talimogene laherparepvec (T-VEC) is a genetically modified herpes simplex type 1 virus and known as an effective oncolytic immunotherapy for injectable cutaneous, subcutaneous and nodal melanoma lesions in stage IIIB-IVM1a patients, as approved by the European Medicines Agency (EMA). The objective of the current study was to identify prognostic factors for achieving a complete response (CR) that can be used to select patients for treatment with T-VEC monotherapy.

Methods

Patients with stage IIIB-IVM1a melanoma, treated with T-VEC at the Netherlands Cancer Institute between 2016-12 and 2019-05 with a follow-up time > 6 months, were included. Data was collected on baseline characteristics, responses and adverse events (AEs). Uni- and multivariable analyses were conducted and a prediction model was developed to identify prognostic factors associated with CR.

Results

A total of 71 patients were included with a median age of 68 years (range: 35-90). The median follow-up time was 16.1 months. As best response, 47 patients (66%) had a CR and 10 patients (14%) had a PR, resulting in an overall response rate of 80%. Twenty-one patients (30%) stopped treatment because of progressive disease and 16 patients (32%) developed a recurrence during follow-up after achieving a PR or CR. Median duration of CR was 11 months. The durable response rate (objective response lasting continuously > 6 months) was 42%. Grade 1-2 AEs occurred in almost every patient. Tumor size, type of metastases, prior treatment with systemic therapy and stage (8^Th AJCC) were independent prognostic factors for achieving a CR. The prediction model includes the predictors tumor size, type of metastases (only cutaneous vs. subcutaneous (+/- cutaneous) vs. nodal (+/- cutaneous/subcutaneous)) and number of lesions.

Conclusions

This study shows that intralesional T-VEC monotherapy for stage IIIB-IVM1a melanoma is able to achieve high complete and durable response rates. The prediction model shows that use of T-VEC in patients with less tumor burden is associated with better outcomes, suggesting T-VEC should perhaps be used earlier in the course of the disease.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

V. Franke: Advisory/Consultancy, Research grant/Funding (self): Amgen. M. Wouters: Research grant/Funding (self): Novartis. W.J. van Houdt: Advisory/Consultancy, Research grant/Funding (self): Amgen. A.C.J. van Akkooi: Advisory/Consultancy, Research grant/Funding (self): Bristol-Myers Squibb; Advisory/Consultancy, Research grant/Funding (self): Novartis; Advisory/Consultancy: MSD-Merck; Advisory/Consultancy: Merck-Pfizer; Advisory/Consultancy: 4SC; Advisory/Consultancy, Research grant/Funding (self): Amgen. All other authors have declared no conflicts of interest.