Neoadjuvant survivin-targeted immunotherapy maveropepimut-S (MVP-S) to increase Th1 immune response in Ki67-high hormone receptor-positive (HR+) early-stage breast cancer (ESBC).

Publication Title

Meeting Abstract | 2022 ASCO Annual Meeting I

Document Type

Abstract

Publication Date

6-2-2022

Keywords

oregon; portland; chiles

Abstract

Background: HR+ ESBC is associated with suboptimal pathologic complete response rate (pCR, ̃10%) following neoadjuvant cytotoxic chemotherapy. Neoadjuvant anti-endocrine therapy with aromatase inhibitors (AI) may serve as an effective alternative. Efficacy can be gauged using the surrogate Ki67 cell proliferation histologic marker. Patients with poor Ki67 response (defined as Ki67 > 10%) following neoadjuvant AI exhibit poor prognosis and therapeutic resistance to both anti-endocrine therapy and chemotherapy. In a genomic analysis among Ki67-high HR+ tumors, we identified 8-fold upregulation of BIRC5 (survivin), a gene that regulates apoptosis and the cell cycle and that is associated with poor clinical outcome. Maveropepimut-S (MVP-S, previously named DPX-Survivac) leverages the non-aqueous, lipid-based DPX delivery platform to educate a specific and persistent T cell-based immune response to 5 HLA-restricted peptides from Survivin, a cancer-associated protein commonly upregulated in several cancers. Treatment with MVP-S and intermittent, low-dose cyclophosphamide (CPA) has shown tumor infiltration of survivin-specific T cells. Previous clinical trials have shown that MVP-S is well-tolerated, immunogenic, and could lead to clinical response in several cancer indications. Further exploration of the regimen in breast cancer could extend the application of this immunotherapy for this unmet medical need. Methods: NCT04895761 is phase I trial evaluating the safety and immunologic effects of neoadjuvant MVP-S plus letrozole (arm A, n = 6), with/without tumor-directed MR-guided radiotherapy (arm B, n = 6), or intermittent low-dose cyclophosphamide or CPA (arm C, n = 6). Postmenopausal patients with T1c+ HR+HER2- breast cancer with Ki67 > 10% will receive two doses of MVP-S and 7 weeks of neoadjuvant letrozole prior to surgery (all arms), whereas arm B will be treated additionally with concurrent 10Gy x 2 tumor boost radiation to facilitate immunogenic cell death, and arm C (n = 6) will be treated additionally with intermittent low-dose CPA (50mg BID) to facilitate regulatory T cell depletion. The primary objective is safety. Biomarker objectives are to evaluate for each treatment arm: 1) systemic type I survivin-specific immune response, as measured by IFN-γ ELISPOT; 2) changes in immune environment by GeoMx digital spatial genomic profiling; 3) and changes in tumor infiltrating lymphocytes (TILs) and Ki67. These data will be used to identify the most immunogenic MVP-S combination therapy for study in phase II trial powered to assess clinical outcome (pCR). Clinical trial information: NCT04895761.

Area of Special Interest

Cancer

Area of Special Interest

Women & Children

Specialty/Research Institute

Oncology

Specialty/Research Institute

Earle A. Chiles Research Institute

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