A Phase 2 multi-center clinical trial in 77 colorectal cancer patients using CTP37-DT, one of the early formulations of CG201, was reported in 2001. The trial demonstrated that CTP37-DT could produce substantial antibody responses in patients with advanced cancer who had failed conventional therapy with negligible side effects. A comparison of patients who responded to the vaccine with levels of antibodies against hCG above the median titer with those whose responses were below the median, showed that patients with the higher antibody levels lived almost twice as long, with median survival times of 44.9 weeks versus 23.6 weeks (p = 0.0002). In contrast, patients who produced above-median titers of antibodies to the DT carrier molecule of the vaccine showed no increase in survival.

Antibody immune responses correlated with survival in colorectal cancer patients receiving CTP37-DT vaccine immunotherapy. Cancer patients who developed high levels of anti-hCG antibodies in response to CTP37-DT showed increased survival times. Blue areas indicate survival of high-titer (above-median) patients; purple areas represent survival by low-titer (below-median) patients. The graphs show significantly longer survival among patients with higher anti-hCG titers (top panel), contrasted with insignificant survival benefit of high anti-DT carrier protein titers (lower panel).

A further Phase 2 clinical study of CTP37-DT plus the LP20h-DT immunogen was undertaken in 55 pancreatic cancer patients. Subjects were treated with the CTP37/LP20h formulation alone or in combination with the chemotherapy agent, gemcitabine. The one-year survival rate for the vaccine-alone group was similar to that for gemcitabine alone (~15%), but the vaccine-alone patients had no systemic side effects, in contrast to the often-severe side effects associated with gemcitabine. One-year survival for the patient group treated with vaccine plus gemcitabine was 30%, which was significantly better than either treatment alone, suggesting that anti-hCG inoculations might be useful as co-therapeutic treatments with other modalities such as chemotherapy.