Talimogene laherparepvec (T-VEC), an attenuated oncolytic virus, combined with pembrolizumab, an immune checkpoint inhibitor, passed an early safety evaluation for unresectable melanoma.
Georgina V. Long, BSc, PhD, MBBS
Talimogene laherparepvec (T-VEC), an attenuated oncolytic virus, combined with pembrolizumab, an immune checkpoint inhibitor, passed an early safety evaluation for unresectable melanoma, reported investigators at this year’s European Cancer Congress (ECC).1
Treatment-related grade 3 adverse events occurred infrequently in a small phase Ib trial of combination therapy with T-VEC and pembrolizumab. No patient discontinued treatment due to adverse events, and treatment-related deaths did not occur.
“T-VEC plus pembrolizumab was well tolerated, and we observed no dose-limiting toxicity,” said Georgina V. Long, BSc, PhD, MBBS, associate professor at the University of Sydney in Australia. “Treatment-related adverse events were mostly grade 1/2. The combination of T-VEC and pembrolizumab is feasible and warrants further investigation.”
PD-1/PD-L1 inhibitors, such as pembrolizumab, demonstrated activity in advanced melanoma, which has stimulated interest in combination strategies to improve outcomes in patients who have advanced disease. T-VEC is an oncolytic herpes simplex virus type 1 engineered to replicate selectively in tumor cells and express human granulocyte macrophage-colony stimulating factor (GM-CSF).
A recently reported study showed that T-VEC treatment improved durable response in advanced melanoma.2An as-yet unpublished phase Ib study showed that the combination of T-VEC and ipilimumab resulted in an overall response rate of 50%, durable response rate of 44%, and tolerable safety profile in patients with advanced melanoma, added Long.
Investigators enrolled 21 patients with unresectable stage III/IV melanoma and no prior treatment. Those with clinically active brain metastases or active herpetic skin lesions (or a history of complications from herpetic infection) were excluded.
Five weeks prior to initiating pembrolizumab, patients received intralesional T-VEC injection at doses up to 4 mL per treatment (106PFU/mL, then 108PFU/mL every 2 weeks). Pembrolizumab (200) mg was then administered intravenously every 2 weeks at week 0. Dose-limiting toxicity was assessed during weeks 0 to 6.
Treatment continued until disease progression, development of intolerance, injectable tumor disappearance (T-VEC only), or 2 years. The primary endpoint was the incidence of dose-limiting toxicity.
Women accounted for 13 of the 21 patients, and 8 of the 21 had stage III disease at enrollment. About 20% of the patients hadBRAF-positive melanoma. All patients received one or more doses of T-VEC and pembrolizumab. Median treatment duration was 13.1 weeks, and seven infusions for T-VEC and 10.1 weeks and five infusions for pembrolizumab.
The most common adverse events of any grade were rash and pyrexia (each reported in 9 patients), fatigue (8), chills and nausea (7 each), headache and vomiting (5 each), diarrhea, arthralgia, and pruritus (4 each), and influenza-like illness and peripheral edema in 3 patients each.
Six patients had grade 3 adverse events, including four patients who had a total of five treatment-related adverse events (one case each of anemia, hyperglycemia, macular rash, headache, and generalized rash). Treatment-related grade 4 adverse events were not reported, said Long.
Analysis of the timing of treatment-related adverse events showed spikes at the start of T-VEC, as well as the initiation of pembrolizumab.
Serious adverse events consisted of one case of grade 5 hypovolemic shock that was not considered treatment related, and one case of grade 1 treatment-related cytokine release syndrome, which occurred early after initiation of pembrolizumab and did not recur.
One case of T-VECassociated treatment interruption occurred during T-VEC monotherapy and two cases during T-VEC plus pembrolizumab. Four pembrolizumab-related treatment interruptions occurred.
Long said the safety data reported at ECC are as of June 10, and efficacy data are still being analyzed. Even so, a phase III continuation of the trial has been planned, comparing the combination to pembrolizumab alone. Pembrolizumab will be started concurrently with T-VEC, and the dosing interval for pembrolizumab will be increased to every 3 weeks.