Takuya Osada

PURPOSE: Triple-negative breast cancer (TNBC) is an aggressive disease with limited therapeutic options. Antibodies targeting programmed cell death protein 1 (PD-1)/PD-1 ligand 1 (PD-L1) have entered the therapeutic landscape in TNBC, but only a minority of patients benefit. A way to reliably enhance immunogenicity, T-cell infiltration, and predict responsiveness is critically needed. PATIENTS AND METHODS: Using mouse models of TNBC, we evaluate immune activation and tumor targeting of intratumoral IL12 plasmid followed by electroporation (tavokinogene telseplasmid; Tavo). We further present a single-arm, prospective clinical trial of Tavo monotherapy in patients with treatment refractory, advanced TNBC (OMS-I140). Finally, we expand these findings using publicly available breast cancer and melanoma datasets. RESULTS: Single-cell RNA sequencing of murine tumors identified a CXCR3 gene signature (CXCR3-GS) following Tavo treatment associated with enhanced antigen presentation, T-cell infiltration and expansion, and PD-1/PD-L1 expression. Assessment of pretreatment and posttreatment tissue from patients confirms enrichment of this CXCR3-GS in tumors from patients that exhibited an enhancement of CD8+ T-cell infiltration following treatment. One patient, previously unresponsive to anti-PD-L1 therapy, but who exhibited an increased CXCR3-GS after Tavo treatment, went on to receive additional anti-PD-1 therapy as their immediate next treatment after OMS-I140, and demonstrated a significant clinical response. CONCLUSIONS: These data show a safe, effective intratumoral therapy that can enhance antigen presentation and recruit CD8 T cells, which are required for the antitumor efficacy. We identify a Tavo treatment-related gene signature associated with improved outcomes and conversion of nonresponsive tumors, potentially even beyond TNBC.

BACKGROUND: There remains a significant need to eliminate the risk of recurrence of resected cancers. Cancer vaccines are well tolerated and activate tumor-specific immune effectors and lead to long-term survival in some patients. We hypothesized that vaccination with alphaviral replicon particles encoding tumor associated antigens would generate clinically significant antitumor immunity to enable prolonged overall survival (OS) in patients with both metastatic and resected cancer. METHODS: OS was monitored for patients with stage IV cancer treated in a phase I study of virus-like replicon particle (VRP)-carcinoembryonic antigen (CEA), an alphaviral replicon particle encoding a modified CEA. An expansion cohort of patients (n=12) with resected stage III colorectal cancer who had completed their standard postoperative adjuvant chemotherapy was administered VRP-CEA every 3 weeks for a total of 4 immunizations. OS and relapse-free survival (RFS) were determined, as well as preimmunization and postimmunization cellular and humoral immunity. RESULTS: Among the patients with stage IV cancer, median follow-up was 10.9 years and 5-year survival was 17%, (95% CI 6% to 33%). Among the patients with stage III cancer, the 5-year RFS was 75%, (95%CI 40% to 91%); no deaths were observed. At a median follow-up of 5.8 years (range: 3.9-7.0 years) all patients were still alive. All patients demonstrated CEA-specific humoral immunity. Patients with stage III cancer had an increase in CD8 +TEM (in 10/12) and decrease in FOXP3 +Tregs (in 10/12) following vaccination. Further, CEA-specific, IFNγ-producing CD8+granzyme B+TCM cells were increased. CONCLUSIONS: VRP-CEA induces antigen-specific effector T cells while decreasing Tregs, suggesting favorable immune modulation. Long-term survivors were identified in both cohorts, suggesting the OS may be prolonged.

Photodynamic therapy (PDT) ablates malignancies by applying focused near-infrared (nIR) light onto a lesion of interest after systemic administration of a photosensitizer (PS); however, the accumulation of existing PS is not tumor-exclusive. We developed a tumor-localizing strategy for PDT, exploiting the high expression of heat shock protein 90 (Hsp90) in cancer cells to retain high concentrations of PS by tethering a small molecule Hsp90 inhibitor to a PS (verteporfin, VP) to create an Hsp90-targeted PS (HS201). HS201 accumulates to a greater extent than VP in breast cancer cells both in vitro and in vivo, resulting in increased treatment efficacy of HS201-PDT in various human breast cancer xenografts regardless of molecular and clinical subtypes. The therapeutic index achieved with Hsp90-targeted PDT would permit treatment not only of localized tumors, but also more diffusely infiltrating processes such as inflammatory breast cancer.

<jats:title>Abstract</jats:title> <jats:p>Background: Previous studies have reported that tumor debris and inflammation made by high-intensity focused ultrasound (HIFU) therapy induced the antitumor immune response, however, HIFU as a monotherapy is still not potent enough to eradicate tumors and treat distant metastasis. We have reported that mechanical HIFU (M-HIFU), that will mechanically destroy tumor cells/tissues through acoustic cavitation, induced stronger antitumor immune response compared to conventional thermal HIFU (T-HIFU) that will cause thermal ablation of tumors. In the present study, we established an immune based combination therapy of M-HIFU and immune checkpoint blockade to enhance systemic antitumor immune response and treated distant/metastatic tumors in murine breast cancer models.</jats:p> <jats:p>Methods and Results: HER2 oncogene-dependent murine breast cancer cell line, MM3MG-HER2, was established in our lab. In mice with bilateral implantation of MM3MG-HER2 tumors, M-HIFU monotherapy induced stronger HER2-specific cellular response and inhibited the growth of HIFU-untreated distant tumors as well as HIFU treated-tumors, more potently than T-HIFU. Flow cytometry and immunohistochemical analysis of tumor microenvironment revealed significantly stronger accumulation of activated T cell and NK cells in M-HIFU-treated tumors. On the other hand, M-HIFU induced stronger expression of programmed death-ligand 1 (PD-L1) on various immune cells in both sides of tumors than T-HIFU therapy or no treatment control. Based on these findings, we investigated the combination therapy of M-HIFU and PD-1/PD-L1 axis blockades, and found significantly enhanced tumor-specific cellular immune response compared to each monotherapy, which resulted in improved therapeutic effect against distant tumors as well as HIFU treated-tumors. Furthermore, immune cell depletion studies demonstrated that both CD8+ T cells and NK cells played an essential role for the antitumor efficacy in this combinatory therapy against both HIFU-treated tumors and untreated distant tumors.</jats:p> <jats:p>Conclusion: this study provides strong rational evidence that M-HIFU combined with PD-1/PD-L1 axis blockades could be a promising treatment strategy against advanced breast cancer with metastatic lesion.</jats:p> <jats:p>Citation Format: Shinya Abe, Takuya Osada, Kensuke Kaneko, Pei Zhong, Herbert K. Lyerly. A novel combination therapy of high intensity focused ultrasound and PDL1 blockades against advanced breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4071.</jats:p>