SELLAS Life Sciences Announces Completion of Enrollment in Phase 2 Randomized Controlled Clinical Study

SELLAS Life Sciences Group, Inc. recently announced the completion of enrollment for a Phase 2 independent investigator-sponsored clinical trial of the combination of trastuzumab (Herceptin) +/- nelipepimut-S (NPS) targeting high-risk, high-expression HER2-positive (IHC3+) breast cancer patients. This trial enrolled 100 patients and top-line data are expected in the fourth quarter of 2019. SELLAS recently reported positive data from a separate Phase 2b study of trastuzumab +/- NPS in low-expression HER2 (IHC 1+/2+) or triple negative breast cancer patients whose tumors are also identified by low-to-no expression of hormone receptors.

This trastuzumab + NPS clinical study is a multi-center, prospective, randomized, single-blinded investigator-sponsored Phase 2 trial focusing on patients with a diagnosis of HER2-positive (immunohistochemistry [IHC] 3+ and/or HER2 FISH-amplified) breast cancer who are HLA-A02, A03, A24 or A26-positive and at high-risk for recurrence after standard therapy for early stage disease. Eligible patients were randomized to receive NPS plus trastuzumab or trastuzumab alone in the adjuvant setting to prevent or delay disease recurrence. The primary endpoint of the study is disease-free survival (DFS). Support for this trial is provided, in part, by the Congressionally Directed Medical Research Program (CDMRP), funded through the Department of Defense via a Breast Cancer Research Program Breakthrough Award to Elizabeth Mittendorf, MD, PhD. The National Breast Cancer Coalition led the effort to establish the CDMRP to enhance the funding for breast cancer research and remains integrally involved in the grant selection process.

“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,” said Dr. Nicholas J. Sarlis, MD, PhD, Executive Vice President and Chief Medical Officer of SELLAS. “We are encouraged for a favorable outcome based on rigorous preclinical work showing potential synergy between NPS and trastuzumab, and are eager to gain further insights on the effect of this combination in HER2-positive early-stage breast cancer in patients with the highest risk of disease recurrence. 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. We look forward to reporting data from this second combination study next year.”

“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. We look forward to completing the study and to reporting the trial results,” added Elizabeth A. Mittendorf, MD, PhD, Rob and Karen Hale Distinguished Chair in Surgical Oncology, Director of Research, Breast Surgical Oncology at Brigham and Women’s Hospital, and Director, Breast Immuno-Oncology Program Dana-Farber/Brigham and Women’s Cancer Center and the Principal Investigator of the study. “The addition of trastuzumab to standard therapy has dramatically improved the prognosis for patients with early stage, HER2-positive (IHC 3+/HER2 gene FISH-amplified) breast cancer to unprecedented survival outcomes. Yet, long-term follow-up data indicate that 15-24% of such patients still develop recurrent disease. Moreover, dual blockade of HER2 signaling in the adjuvant setting has led to only small incremental benefits in disease-free survival and the addition of NPS may prove to be clinically beneficial and enhance the armamentarium in breast cancer treatments.  This unmet medical need is more prevalent in patients who are unable to achieve a pathologic complete response after standard neoadjuvant therapy or those found to have positive lymph nodes above certain number thresholds at the time of surgery, and then treated with standard adjuvant therapy.”

 SELLAS is a clinical-stage biopharmaceutical company focused on novel cancer immunotherapeutics for a broad range of cancer indications. SELLAS’ lead product candidate, galinpepimut-S (GPS), is licensed from Memorial Sloan Kettering Cancer Center and targets the Wilms Tumor 1 (WT1) protein, which is present in an array of tumor types. GPS has potential as a monotherapy or in combination to address a broad spectrum of hematologic malignancies and solid tumor indications. SELLAS has Phase 3 clinical trials planned (pending funding availability) for GPS in two indications, acute myeloid leukemia (AML) and malignant pleural mesothelioma (MPM) and is also developing GPS as a potential treatment for multiple myeloma (MM) and ovarian cancer. For more information on SELLAS, please visit