Cancer vaccine is focus of breast cancer study at Providence

An investigator-initiated trial offered at the Earle A. Chiles Research Institute, a division of Providence Cancer Institute of Oregon, is enrolling patients with early-stage HR-positive (HR+) and HER2-negative (HER2-) breast cancer for a 3-arm study.  

The trial will evaluate the safety of aromatase inhibitor letrazole given in combination with the experimental cancer vaccine maveropepimut-S (MVP-S, previously named DPX-Survivac), MVP-S plus MRI-guided radiation therapy, or MVP-S with the chemotherapy cyclophosphamide. Earlier trials have shown that MVP-S is well-tolerated, immunogenic and could lead to clinical response in several cancer types. 

The principal investigator is Sasha Stanton, M.D., Ph.D., medical oncologist and assistant member, Cancer Immunoprevention Laboratory at the Earle A. Chiles Research Institute.  

In December 2022, Dr. Stanton presented the study at the 2022 San Antonio Breast Cancer Symposium and subsequently was invited to discuss the trial in an interview with OncLive.  

Bolstering the Th1 immune response  

In recent studies, patients with triple negative breast cancer have derived some benefit from immunotherapy. But the same cannot be said for patients with HR+ early-stage breast cancer. “They don’t have the same kind of immune response infiltrating the tumor and they don’t respond to immunotherapies the same way,” said Dr. Stanton.  

For this study, investigators will evaluate if they can modify the tumor immune microenvironment in patients with Ki67-high, HR+ and HER2- early-stage breast cancer to improve the response to MVP-S, a type of immunotherapy, prior to surgery. Ki67 is a tumor marker, and Ki67-high tumors are associated with poorer outcomes in breast cancer patients.  

MVP-S targets survivin, a protein that is more abundant in HR+HER2- tumors. MVP-S creates a depot at the injection site where survivin antigens are released. By exposing the immune system to the therapy for an extended period, the desired outcome is a strong and sustained type 1 T helper cell (Th1) suvivin-specific immune response. 

3-arm study to evaluate safety prior to surgery 

In the first arm of the study patients receive letrazole with MVP-S to ensure its safety.  Enrollment in this arm is nearly complete and treatment has been very well tolerated.

“In subsequent arms we want to see if we can enhance that immune response by giving a low dose of cyclophosphamide or by using targeted radiation prior to surgery,” said Dr. Stanton.  

Cyclophosphamide reduces the amount of regulatory T cells, while targeted radiation helps kill cancer cells.  

All trial participants will have surgery to remove the tumor at the end of the study, which could last up to nine weeks. Dr. Stanton said the trial will continue as a phase 2 study for patients with advanced HR+ and HER- breast cancer if they have good clinical results in this trial. 

Learn more about the trial here: 

Early phase study of DPX-Survivac, aromatase inhibition, and with/without radiotherapy or cyclophosphamide in HR+HER2- breast cancer 

For more information about this study or to refer a patient, please contact our clinical research office: 

See more breast cancer studies  

Research studies investigating a broad spectrum of breast cancer therapies and interventions are open at Providence Cancer Institute. We offer studies aimed at improving cure rates, quality of life and survival for early-stage and metastatic breast cancer. These studies range from our own investigator-initiated trials to studies sponsored by the National Cancer Institute.  

New studies are added frequently. Visit our website to view all breast cancer studies

A team of breast cancer specialists  

Providence Cancer institute offers a comprehensive, multidisciplinary approach to breast care. Achieving optimal breast health and providing world-class treatment for breast cancer are equal priorities in our continuing goal to improve women's health.   

Our clinical and research teams include surgeons dedicated to breast care and reconstruction, oncologists who specialize exclusively in breast cancer, as well as breast-cancer-focused nurse navigators and research nurses, genetic specialists, nutrition counselors, oncology social workers, laboratory scientists, data coordinators and lab assistants. Every person on this team is passionate about providing the best possible care and the best available treatments for women with breast cancer.  

To learn more, visit Providence Breast Cancer Program.

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