Subsequently measured data for a patient with missing data will be analyzed. 4.8.7 Determination of Sample Size The primary endpoint of DFS at 24 months is used to determine the sample size and follow-up determination, based on the following background. The previously described Phase 2 NeuVax study (USMCI Clinical Trials Group Study I-01 and I-02) (n=188) has reported 26 DFS events and 8 deaths with a 60-month median follow-up; this translates into an 88% DFS for vaccinated patients versus 78% for controls. In 24-month landmark analysis, the vaccinated patients had a 93.5% DFS compared to 85.5% in the control group. The DFS hazard ratio was 0.54 at 60 months and 0.45 at 24 months. In this study, the 24 months was measured from enrollment which was on average 6 months from completion of all standard of care therapy or approximately one year from surgery. This analysis equates to 3-year analysis in studies that enroll at initiation of chemotherapy such as the Herceptin studies. Unlike the Herceptin studies, this study enrolled both NP and high-risk NN patients which decreased the overall recurrence rate. The NSABP adjuvant Herceptin studies (n=3351 combined) reported an 87% DFS rate at three years, a 90% distant recurrence-free rate at three years, and a 91% OS rate at four years for the combined Herceptin groups (plus adjuvant chemotherapy) versus a 75% DFS rate at three years, an 82% distant recurrence-free rate at three years, and a 87% OS rate at four years for the combined chemotherapy control; the DFS hazard ratio was 0.48 (p<0.0001) while the OS hazard ratio was 0.67 (p=0.015). The adjuvant Herceptin (HERA) study (n=5081 total) reported an 86% DFS rate at two years, a 91% distant recurrence free rate at two years, and a 96% OS rate at two years for the combined Herceptin groups (plus adjuvant chemotherapy) versus a 77% DFS rate at two years, an 83% distant recurrence free rate at 2 years, and a 85% OS rate at two years for the combined chemotherapy control; the DFS hazard ratio was 0.54 (p<0.0001) while the OS hazard ratio was 0.76 (p=0.26). The recurrence rate among NP breast cancer patients with HER2 1+ and 2+ expressing tumors after standard of care therapy is reported to be 20% at 24 months, which is comparable to the two-year DFS of 77% observed in the HERA trial. CONFIDENTIAL Page 42 of 102 Protocol: HERCEPTIN® + E75/GM-CSF Version 3.1 ML25749 05 March 2017 As described above, the 3-year DFS in the NSABP trial is equivalent to the 24-month DFS we intend to analyze as our primary endpoint in this trial based on differences in time of enrollment. Based on this data, we expect Herceptin alone (with GM-CSF) may have some benefit and decrease the recurrence rate to 15%, similar to that seen in the NSABP trial. However, the combination of Herceptin + E75/GM-CSF based on preliminary data virtually eliminated recurrences (Sears et al, 2011). For planning purposes, if the combination reduces the recurrence rate to 5%, then in order to show a statistical differences between recurrence rates of 15% versus 5%, a sample size of 150 patients per arm would be required or a study size of 300 patients. The overall type 1 error rate of 5% will be preserved for the rejection of the null hypothesis in favor of the alternative hypothesis that Herceptin + E75/GM-CSF will prolong DFS over that of Herceptin + GM-CSF alone. With this sample size, the power to detect our primary endpoint is 80%.