Tam A, Ladbury CJ, Kassardjian A, Melstrom L, Modi B, Margolin K, Xing Y, Amini A. Synergistic Effect of TVEC and Radiotherapy in the Treatment of Advanced Melanoma.
Int J Radiat Oncol Biol Phys 2023;
117:e342. [PMID:
37785193 DOI:
10.1016/j.ijrobp.2023.06.2405]
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Abstract
PURPOSE/OBJECTIVE(S)
Talimogene laherparepvec (TVEC) is a genetically modified herpes simplex virus (HSV-1) that has been approved by the US Food and Drug Administration (FDA) for intralesional treatment of melanoma. Recent reports have suggested that radiation treatment (RT) given in conjunction with TVEC, may provide synergistic immune enhancement at the site, and possibly systemically. However, the studies on combining RT with TVEC remain limited. Our study compares melanoma patients (pts) who received TVEC and RT in the same region of the body with pts whose RT field did not include the site of TVEC injection. We hypothesized that RT and TVEC to the same site would induce a more robust local tumor response, and possibly a systemic response, with improvement in clinical outcomes over those pts who had treatments in different regions.
MATERIALS/METHODS
This was a retrospective review of 20 melanoma pts from a single cancer center who were treated with TVEC and RT between January 2015 and September 2022. Overall survival (OS), progression-free survival (PFS), time to distant metastasis (DM), and time to locoregional recurrence (LRR) were compared using Kaplan-Meier analysis and the corresponding log-rank test. Skin toxicity was also tabulated.
RESULTS
Fourteen pts (stage III [71.4%]; stage IV [28.6%]) received TVEC and RT in the same region (left leg [5], right leg [5], back [1], left arm [1], and right arm [1], and scalp [1]), and six (stage III [66.7%]; stage IV [33.3%]) received treatments in separate regions. The overall median follow-up was 10.5 months (mos) (range 1.0 - 58.7 mos). The OS of pts who had TVEC and RT in the same region was 19.0 mos (95% confidence interval [CI], 4.1 - not reached [NR] mos), compared to 18.5 mos for those receiving RT in a different region (95% CI, 1.0 - NR mos) (p = 0.366). PFS with TVEC and RT in the same and different regions were 6.4 mos (95% CI, 2.4 - NR mos) and 2.8 mos (95% CI, 0.7 - 4.4 mos) respectively (p = 0.005). DM was 13.8 mos (95% CI, 4.6 - NR mos) with TVEC and RT in the same field and 2.8 mos (95% CI, 0.7 - 4.4 mos) in different fields (p = 0.001). Lastly, LRR of pts who had TVEC and RT in the same region was 26.0 mos (95% CI, 6.4 - 26.0 mos) compared to 4.4 mos in different regions (95% CI, 0.7 - NR mos) (p = 0.115). No grade 3 or higher skin toxicities were documented among pts who had TVEC and RT in the same region.
CONCLUSION
Comparing pts who had TVEC and RT to different regions of the body, there was an association with improvements in PFS and DM when both modalities were delivered to the same region of the body. However, we did not find a significant difference in locoregional recurrence or OS. Given some promise with the combined approach and potential immune enhancement from RT, larger trials are needed to better understand the potential positive signal from our study.
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