Patterns of response with talimogene laherparepvec in combination with ipilimumab or ipilimumab alone in metastatic unresectable melanoma

Talimogene laherparepvec (T-VEC) has demonstrated efficacy for unresectable melanoma. We explored response patterns from a phase 2 study evaluating patients with unresectable stage IIIB–IVM1c malignant melanoma who received T-VEC plus ipilimumab or ipilimumab alone. Patients with objective response per modified irRC were evaluated for pseudo-progression (single ≥25% increase in tumour burden before response). Patients without pseudo-progression were classified by whether they responded within or after 6 months of treatment start; those with pseudo-progression were classified by whether pseudo-progression was due to increase in existing lesions or development of new lesions. Overall, 39% (n = 38/98) in the combination arm and 18% (n = 18/100) in the ipilimumab arm had an objective response. Eight responders (combination, n = 7 [18.4%]; ipilimumab, n = 1 [5.6%]) had pseudo-progression; most occurred by week 12 and were caused by an increase in existing lesions. These data reinforce use of T-VEC through initial progression when combined with checkpoint inhibitors. Trial Registration NCT01740297 (ClinicalTrials.gov; date of registration, December 4, 2012); 2012-000307-32 (ClinicalTrialsRegister.eu; date of registration, May 13, 2014).