E323: A Single Institution Experience Using Ultrasound-Guided Intralesional Immunotherapy in Recurrent Melanoma

Intralesional therapy for recurrent melanoma is well-established for palpable lesions, however, the benefit of ultrasound-guided (US) injections for non-palpable melanoma has not been well-established. Our objective was to evaluate the safety and efficacy of US-guided injection of talimogene laherparepvec (T-VEC) in the treatment of advanced melanoma.  

Methods:

A single-institution retrospective chart review was conducted to identify patients ≥18 years old who received intralesional T-VEC injections for advanced melanoma between 2018-2023. T-tests, Fisher’s exact tests and Chi-squared tests compared patient and treatment characteristics, side effects and outcomes between US-guided and non-US guided injections.

Results:

Of 36 patients, 11 (31%) underwent US-guided and 25 (69%) underwent non-US-guided TVEC injections. The median (IQR) follow up was 6 (6) months. There were no differences in patient demographics or past medical history between US and non-US guided injections. The majority of patients were treated for recurrent or metastatic melanoma. The most common location of lesions were lower extremity, upper extremity and trunk. Patients undergoing US-guided injections had mean (SD)  8.3 (4.96) total injection cycles and non-US guided had 4.5 (3.27) injection cycles (p=0.03). Additionally, most patients (86%) received combination T-VEC therapy with systemic pembrolizumab. There were no statistically significant differences in side effects between groups. Three patients without US guidance had injection site reactions, while no complications occurred in the US-guided group. Similar response rates (63.6% US guided vs 60% non-US guided) and progression (36.4% US-guided vs 36% Non-US guided) occurred among both cohorts (p=0.8). The mean (SD) overall survival was 22 (20.8) months for US-guided group and 12.3 (11.7) months for non-US guided. Six-month survival after starting TVEC treatment was 72.7% in US-guided and 76% in non-US guided (p=0.84).

Conclusions:

US-guided injections for non-palpable recurrent melanoma is safe and demonstrates similar efficacy to non-US-guided injections for palpable lesions. US-guided injections of T-VEC for non-palpable melanoma should be considered as a treatment option. Future directions will focus on assessing larger multi-institutional patient cohorts with long-term follow-up.