Prima Biomed Ltd. announced that the first patient has been dosed for the second cohort of its clinical trial program for IMP321 in combination with KEYTRUDA being conducted in Australia. The second cohort will recruit up to six patients with unresectable or metastatic melanoma that have had a suboptimal response to KEYTRUDA. Interim data from the first patient cohort released in December 2016 indicate IMP321 is safe and well tolerated. On the basis of this safety data, the Data Safety Monitoring Board (DSMB) gave approval for the second cohort to commence. TACTI-mel (Two ACTive Immunotherapeutics in melanoma) is a multicentre, open label, Phase I study in which patients with unresectable or metastatic melanoma will be dosed with IMP321 in combination with the PD-1 checkpoint inhibitor pembrolizumab (KEYTRUDA). The study will evaluate safety as the primary endpoint and anti-tumour activity and the immune response to the combination as secondary endpoints.