New immunotherapy yields long-lasting responses in some patients with advanced melanoma
A first-in-class immunotherapy called IMCgp100 yielded durable responses in patients with advanced cutaneous melanoma and those with advanced ocular melanoma, according to data from a phase I/IIa clinical trial presented here at the AACR Annual Meeting 2015, April 18-22.
"IMCgp100 is a new type of immunotherapy that has two functional ends," said Mark R. Middleton, MD, PhD, professor of experimental cancer medicine at the University of Oxford in the United Kingdom. "The targeting end attaches to melanoma cells and the effector end locks on to any neighboring killer T cell [a type of immune cell], resulting in directed destruction of the tumor. One can think of IMCgp100 as a molecular bridge connecting melanoma cells with killer T cells, encouraging the killer T cells to destroy the melanoma cells.
"Last year at the AACR Annual Meeting, we reported the results of the phase I dose-escalation portion of the clinical trial, which showed that IMCgp100 was well tolerated and had efficacy in some patients with advanced melanoma," continued Middleton. "This year, we are reporting data from 17 patients treated with the maximum tolerated dose of 600 nanograms of IMCgp100 per kilogram or an absolute dose of 50 micrograms of IMCgp100 as part of the phase I and phase IIa portions of the trial.
"Among these patients, we observed lasting tumor responses for both cutaneous and ocular melanoma," Middleton added. "Importantly, responses were even observed in patients with advanced melanoma that was resistant to the immune checkpoint inhibitors that have recently become standard of care in many locations."
Two of the 17 patients to receive the maximum tolerated dose of IMCgp100 had advanced ocular melanoma and the others had advanced cutaneous melanoma. Among the 17 patients, three partial responses and one complete response were observed; two of the partial responses are still ongoing and have lasted more than 18 months. The complete response in one patient with advanced ocular melanoma lasted over four months.
"It is too early to say if IMCgp100 is particularly effective in ocular melanoma, although the results are encouraging. These observations will be investigated further, both clinically and experimentally," said Middleton. "We look forward to continuing to follow all the patients who remain on the trial and to enrolling more patients to firmly establish the utility of IMCgp100 as a treatment for advanced melanoma."