Enrollment Complete in Phase 2 Trial of NeuVax-Herceptin for HER2-Positive, High-Risk Breast Cancer

Enrollment Complete in Phase 2 Trial of NeuVax-Herceptin for HER2-Positive, High-Risk Breast Cancer

The investigator-sponsored trial studying a combination of NeuVax (nelipepimut-S, NPS) and Herceptin (trastuzumab) as a maintenance treatment for HER2-positive breast cancer at high risk of recurrence has completed patient enrollment, Sellas Life Sciences, NeuVax’s developer, has announced.

Top-line data from the trial is expected by the end of 2019.

“The completion of enrollment of this Phase 2 clinical trial of NPS marks an important milestone, as it brings us one step closer to providing this potentially life-saving therapy to high-risk HER2-positive breast cancer patients facing limited treatment options,” Nicholas J. Sarlis, MD, PhD, executive vice president and chief medical officer of Sellas, said in a press release.

NeuVax is an investigational cancer vaccine composed of small pieces of the HER2 protein. Once injected into the patient, the vaccine teaches the immune system to recognize the HER2 protein — which is produced in excess in some breast cancers — causing the cancer cells to die.

In an ongoing Phase 2b trial (NCT01570036), which included patients with triple-negative breast cancer — meaning they have low HER2 levels — the vaccine, given in combination with Herceptin as a maintenance treatment, reduced disease recurrence by 74% compared to Herceptin alone.

“This combination has a solid clinical and immunobiological rationale, as demonstrated by the recent data from the Phase 2b study of NPS plus trastuzumab in the maintenance setting in patients with early-stage triple negative breast cancer,” Sarlis said. “We look forward to reporting data from this second combination study next year.”

The fully enrolled Phase 2 trial (NCT02297698) was also designed to test a combination of NeuVax and Herceptin in breast cancer patients, but among those whose tumors produce high levels of the HER2 protein — deemed HER2-positive.

The trial included 100 breast cancer patients at 24 clinical sites across the United States. All patients were at high risk of disease recurrence, as they either did not achieve complete remission with  previous therapies, or had undergone surgery but still had positive lymph node biopsies.

Participants were also screened for HLA type — which defines the subtype of active T cells — to ensure they were positive for HLA-2, HLA-A3, HLA-A24, or HLA-A26 classes, which represent approximately 80% of the U.S. population and for whom NeuVax was particularly designed.

Participants will randomly receive NeuVax or a placebo in combination with Genentech’s approved therapy Herceptin. The investigational vaccine will be administered every three weeks, for a total of six vaccinations, 30 mintues to two hours after completion of Herceptin infusion.

Researchers will evaluate whether the combination is better than Herceptin at preventing or delaying disease recurrence as a primary goal. Secondary objectives include the time patients live without disease spread and measures of immune response. The safety of the treatment will also be assessed.

“We are thrilled to complete enrollment in this very important Phase 2 clinical trial of NPS and trastuzumab as a treatment for high-risk HER2-positive breast cancer patients,” said Elizabeth A. Mittendorf, MD, PhD, director of the Breast Immuno-Oncology Program Dana-Farber/Brigham and Women’s Cancer Center, and principal investigator of the trial.

“We look forward to completing the study and to reporting the trial results,” said Mittendorf, the Rob and Karen Hale Distinguished Chair in Surgical Oncology and director of research, breast surgical oncology at Brigham and Women’s Hospital in Boston.

The trial being supported in part by a Breast Cancer Research Program Breakthrough Award granted to Mittendorf by the Department of Defense.

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