AE37 is an investigational cancer vaccine being developed by Antigen Express, a subsidiary of Generex Biotechnology, to prevent cancer from returning in women with certain types of breast cancer who are clinically disease-free. It is a combination of two proteins that together stimulate the immune system to fight cancer cells.

How AE37 works

Up to 80 percent of breast cancers overproduce a protein called HER2. As a result, many breast cancer treatments target HER2 to fight breast tumors. AE37 consists of a protein derived from HER2 combined with a protein called Ii-Key.

It does not directly target HER2, but instead acts as a vaccine, exposing the immune system to the HER2 protein so immune cells can recognize the protein as foreign.

AE37 specifically activates CD4-positive lymphocytes, immune cells that are important in stimulating both the antibody response (antibodies against HER2) and cellular responses directed against HER2 positive breast cancer cells. The Ii-Key peptide is combined with the HER2 protein to increase the strength of the immune response.

AE37 in clinical trials

The AE37 investigative vaccine has been tested in a prospective Phase 2 clinical trial (NCT00524277) involving 298 women with HER2-positive breast cancer who were clinically disease-free and who either had cancer cells in lymph nodes (called “node-positive”) or nodes that had a high risk of cancer cells (“high-risk node-negative”).

Participants were randomized to receive subcutaneous injections of either AE37 plus granulocyte stimulating factor (GM-CSF) or GM-CSF alone. The effectiveness of the vaccine was measured by the length of time the women remained disease-free, called disease-free survival (DFS).

In a study published in the Journal for ImmunoTherapy of Cancer in 2014, investigators reported that participants who received the AE37 vaccine showed an antibody response directed to HER2, evidence that the vaccine was inducing an immune response. They also reported that the vaccine had been safe and well-tolerated.

After a median follow-up period of 25 months, researchers found no difference in DFS between the women who received AE37 and those who did not. However, after a median follow-up period of 55 months, there was a trend toward improved DFS among subgroups of women when they were divided by cancer stage and level of HER2 expression, a confirmation that the vaccine was safe and well-tolerated.

The authors of this study, published in the Journal of Clinical Oncology in 2017, concluded that the results supported the initiation of a Phase 3 study of AE37.


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