In a prospective, randomized, placebo-controlled, single blind phase IIB, multicenter clinical study, patients with operable HER2 3+ breast cancer treated with GP2 + GM-CSF after trastuzumab had a PFS rate of 100% after 5 years of follow-up compared to 89.4% in patients treated with GM-CSF alone. Here, GP2 is linked to breast carcinoma.