(ChemotherapyAdvisor) – The US Army-developed HER2-targeting E75 peptide anticancer vaccine halved breast cancer recurrence, according to authors of a phase 2 trial at the Army Cancer Vaccine Development Program (CVDP).

While the CVDP’s clinical trial work focuses on the ability of cancer vaccines to reduce the risk of breast cancer recurrence among cancer survivors, the program’s “ultimate goal is to vaccinate at-risk patients who have never had cancer,” according to Col. George Peoples, MD, FACS, chief of surgical oncology at the San Antonio Military Medical Center and director of the CVDP.

Instead of enrolling patients with metastatic disease – a “holdover from trials testing toxic chemotherapies,” Dr. Peoples noted – the CVDP is testing nontoxic vaccines among cancer survivors with healthy immune systems, he said.

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On September 10, the CVDP completed an 11-year-long phase 2 breast cancer recurrence-immunoprevention clinical trial of the E75 peptide anticancer vaccine. The phase 3 trial will begin in January 2013, after phase 2 findings are reported at the San Antonio Breast Cancer Symposium in December.

“The phase 2 trial data has shown that the rate of breast cancer recurrence in women who received E75 was half the rate observed in the control group,” Dr. Peoples said. “We look forward to seeing if the phase 3 trial will confirm these results.”

In an October 2 presentation to the American College of Surgeons’ Clinical Congress, CVDP researchers described data for a phase 1 clinical trial of the cancer vaccine peptide AE37, reporting that AE37 significantly reduced recurrence rates among breast cancer survivors. Patients whose tumors had expressed low levels of HER2 had a survival rate of 89%, versus 70% among placebo-arm patients, the team reported. All patients saw some immunologic response to vaccination with AE37, but patients with more aggressive tumor types did not appear to benefit from lower recurrence rates.

Another CVDP clinical trial will begin recruiting by December, as well, to assess a possible synergistic benefit from combining E75 with trastuzumab (Herceptin) among patients with breast cancer whose tumors exhibit low to moderate HER2/neu expression.

In August, the CVDP began enrollment for a phase 1 trial for another vaccine peptide, called E39. E39 targets breast tumor folate binding protein (FBP), a molecular target for which no drugs are currently available, Dr. Peoples said.

“We are looking at areas of future research in combining vaccines with other forms of immunotherapy,” Dr. Peoples said. “HER2/neu is expressed in other cancers, and we hope to one day have vaccines to prevent lung, colon, prostate and ovarian cancers.”

Despite a highly-mobile population, the military is well positioned to conduct such research, Dr. Peoples noted.

“Military families want to be of service and help others, so they’re more likely to say yes to a clinical trial,” he said.

Electronic patient medical records are shared among military hospitals around the world, yielding high study participant-retention rates, Dr. Peoples said. Breast cancer is one of the most frequently-diagnosed cancers in the US military, he noted.

Dr. Peoples holds inventors’ rights and financial proceeds from commercial development licenses based on clinical trial results, he disclosed.

Read more about CVDP’s current clinical trials at ClinicalTrials.gov.