Merck has announced the presentation of early interim results from a single-arm, open-label phase IB study that has so far enrolled 132 patients with advanced ( inoperable and metastatic ) melanoma who have received Pembrolizumab ( MK-3475 ), an investigational immune-modulating therapy.

Research has shown that PD-1, an immune checkpoint receptor, helps to confer immune resistance for some cancers allowing tumor cells to grow and proliferate unchecked. Pembrolizumab is a monoclonal antibody designed to target PD-1 to disrupt the role PD-1 plays in resisting the immune system.
Patients were administered Pembrolizumab in one of three regimens: low dose every 3 weeks, high dose every 3 weeks and high dose every 2 weeks. Following an initial disease evaluation, patients received one of the three regimens of Pembrolizumab.

After 12 weeks, disease status was evaluated by the investigator and compared to baseline using immune-related response criteria ( irRC ). Those patients demonstrating stable disease or response at the 12-week evaluation time point continued to receive Pembrolizumab and follow-up monitoring.

Data has so far been obtained for 85 of the 132 patients enrolled in the study. Of those patients, a total of 43 patients ( 51% ) showed an objective anti-tumor response, and of those, 8 patients ( 9% ) showed a complete response at or after the 12-week assessment.

Of the 27 patients who had previously been treated with Ipilimumab monotherapy, the current standard of care for late-stage melanoma, 11 patients ( 41% ) showed an objective anti-tumor response to MK-3475 monotherapy; none of those patients showed a complete response.

The most common adverse events experienced by patients who received Pembrolizumab included fatigue, rash, diarrhea, nausea, cough, joint pain, fever and itching. Seven Pembrolizumab related grade 3/4 adverse events were reported as potentially immune related. ( Xagena )

Source: 9th International Congress of the Society for Melanoma Research ( SMR ), 2012

XagenaMedicine2012