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Intramucosal Inoculation of Squamous Cell Carcinoma Cells in Mice for Tumor Immune Profiling and Treatment Response Assessment
Published on: April 22, 2019
Triple-Mutated HSV-1 Expressing Soluble B7-1 Plus CTLA-4 Blockade Suppresses Lymph Node Metastasis in Tongue Cancer
Akinari Sugauchi1, Toshihiro Uchihashi1, Hirotaka Ito2
1Department of Oral and Maxillofacial Surgery, Graduate School of Dentistry, The University of Osaka, Osaka, Japan.
Abstract:
Cervical lymph node metastasis is a major predictor of poor prognosis in patients with oral squamous cell carcinoma (OSCC), underscoring the need for therapies that effectively target metastatic spread. We previously reported that G47Δ, a third-generation oncolytic herpes simplex virus type 1 (HSV-1), rapidly traffics from tongue tumors to cervical lymph nodes and suppresses metastasis in murine models. Based on this lymphotropic property and the immunological significance of CD28-B7-1 interactions for T-cell activation, we pursue the potential of T-mB7-1, a new G47Δ-derived oncolytic HSV-1 expressing soluble murine B7-1. T-mB7-1 secreted soluble B7-1 in vitro without compromising cytopathic activity. In vivo, intratumoral T-mB7-1 suppressed tumor growth in the resistant KLN205-MUC1 subcutaneous model and prolonged survival in SCCVII orthotopic tongue tumors. In the KLN205-MUC1 orthotopic tongue cancer that exhibits rapid lymphatic metastasis, a single dose of T-mB7-1, but not the control virus T-01, significantly reduced cervical lymph node metastasis and improved survival. Repeated low-dose T-mB7-1 further caused near-complete suppression of lymph node metastasis and markedly extended survival. Flow cytometry showed both T-01 and T-mB7-1 induced CD69+ T-cell activation in cervical lymph nodes at 18 h, which was reduced with T-mB7-1 at 24 h. Importantly, combining T-mB7-1 with systemic CTLA-4 blockade markedly prolonged survival of mice harboring orthotopic KLN205-MUC1 tumors, with all treated mice surviving beyond 80 days in the otherwise fatal model. These findings demonstrate that soluble B7-1-expressing oncolytic HSV-1 combined with CTLA-4 blockade durably suppresses lymph node metastasis, providing a promising and minimally invasive strategy for regionally metastatic OSCC.
Insights
A novel oncolytic herpes simplex virus type 1 (HSV-1) therapy, T-mB7-1, effectively targets oral squamous cell carcinoma (OSCC) metastasis. Combining T-mB7-1 with CTLA-4 blockade significantly improves survival in preclinical models.
Area of Science:
- Oncolytic virotherapy
- Cancer immunology
- Oral oncology
Background:
- Cervical lymph node metastasis is a key prognostic factor in oral squamous cell carcinoma (OSCC).
- Oncolytic herpes simplex virus type 1 (HSV-1) G47Δ shows promise in targeting OSCC metastasis.
- CD28-B7-1 interactions are crucial for T-cell activation.
Purpose of the Study:
- To evaluate T-mB7-1, an oncolytic HSV-1 engineered to express soluble murine B7-1, for its efficacy against OSCC metastasis.
- To assess the combination therapy of T-mB7-1 with CTLA-4 blockade.
Main Methods:
- Development of T-mB7-1, an oncolytic HSV-1 expressing soluble B7-1.
- In vitro assessment of T-mB7-1's cytopathic activity and B7-1 secretion.
- In vivo studies using murine models of oral squamous cell carcinoma (KLN205-MUC1 and SCCVII).
- Evaluation of T-mB7-1's effect on tumor growth, lymph node metastasis, and survival.
- Flow cytometry analysis of T-cell activation in cervical lymph nodes.
- Combination therapy with systemic CTLA-4 blockade.
Main Results:
- T-mB7-1 demonstrated retained cytopathic activity and secreted soluble B7-1 in vitro.
- Intratumoral T-mB7-1 suppressed tumor growth and prolonged survival in preclinical OSCC models.
- A single dose of T-mB7-1 significantly reduced cervical lymph node metastasis and improved survival in the KLN205-MUC1 model.
- Repeated low-dose T-mB7-1 led to near-complete suppression of lymph node metastasis and extended survival.
- Both T-01 and T-mB7-1 induced T-cell activation, with T-mB7-1 showing reduced activation at later time points.
- Combination therapy with T-mB7-1 and CTLA-4 blockade resulted in long-term survival in a highly fatal OSCC model.
Conclusions:
- Soluble B7-1-expressing oncolytic HSV-1 (T-mB7-1) is a potent agent against lymph node metastasis in OSCC.
- Combination of T-mB7-1 with CTLA-4 blockade offers a promising, minimally invasive strategy for treating regionally metastatic OSCC.
- This approach demonstrates durable suppression of lymph node metastasis and significantly improved survival.
