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Updated: Dec 25, 2025
Experimental Melanoma Immunotherapy Model Using Tumor Vaccination with a Hematopoietic Cytokine
Published on: February 24, 2023
Identification of Small Molecule Enhancers of Immunotherapy for Melanoma
Christopher Dextras1, Myagmarjav Dashnyam1, Lesley A Mathews Griner1
1Division of Preclinical Innovation, National Center for Advancing Translational Sciences (NCATS), National Institutes of Health, Rockville, Maryland, USA.
Abstract:
Small molecule based targeted therapies for the treatment of metastatic melanoma hold promise but responses are often not durable, and tumors frequently relapse. Response to adoptive cell transfer (ACT)-based immunotherapy in melanoma patients are durable but patients develop resistance primarily due to loss of antigen expression. The combination of small molecules that sustain T cell effector function with ACT could lead to long lasting responses. Here, we have developed a novel co-culture cell-based high throughput assay system to identify compounds that could potentially synergize or enhance ACT-based immunotherapy of melanoma. A BRAFV600E mutant melanoma cell line, SB-3123p which is resistant to Pmel-1-directed ACT due to low gp100 expression levels was used to develop a homogenous time resolve fluorescence (HTRF), screening assay. This high throughput screening assay quantitates IFNγ released upon recognition of the SB-3123p melanoma cells by Pmel-1 CD8+ T-cells. A focused collection of approximately 500 small molecules targeting a broad range of cellular mechanisms was screened, and four active compounds that increased melanoma antigen expression leading to enhanced IFNγ production were identified and their in vitro activity was validated. These four compounds may provide a basis for enhanced immune recognition and design of novel therapeutic approaches for patients with BRAF mutant melanoma resistant to ACT due to antigen downregulation.
Insights
Researchers identified four compounds that enhance adoptive cell transfer (ACT) immunotherapy for melanoma by increasing tumor antigen expression. These compounds may overcome resistance in BRAF-mutant melanoma, leading to more durable responses.
Area of Science:
- Oncology
- Immunology
- Pharmacology
Background:
- Metastatic melanoma treatments like targeted therapies and adoptive cell transfer (ACT) immunotherapy show promise but face challenges.
- Targeted therapies often yield non-durable responses with tumor relapse, while ACT immunotherapy resistance arises from decreased tumor antigen expression.
- Combining small molecules to sustain T cell function with ACT could improve durable responses in melanoma patients.
Purpose of the Study:
- To develop a novel high-throughput screening assay for identifying compounds that enhance ACT immunotherapy in melanoma.
- To discover small molecules that can overcome resistance in BRAF-mutant melanoma by increasing antigen expression.
Main Methods:
- A co-culture, cell-based high-throughput assay system was developed using a BRAF V600E mutant melanoma cell line (SB-3123p) resistant to Pmel-1 ACT due to low gp100 expression.
- A homogeneous time-resolved fluorescence (HTRF) screening assay was established to quantify Interferon-gamma (IFNγ) release upon recognition of melanoma cells by Pmel-1 CD8+ T-cells.
- Approximately 500 small molecules targeting diverse cellular mechanisms were screened.
Main Results:
- Four active compounds were identified that increased melanoma antigen expression.
- These compounds led to enhanced IFNγ production, indicating improved T cell recognition and effector function.
- The in vitro activity of these four compounds was validated.
Conclusions:
- The identified compounds enhance melanoma antigen expression, potentially overcoming ACT resistance.
- These compounds may form the basis for novel therapeutic strategies to improve immune recognition in BRAF-mutant melanoma.
- This research offers a new approach for patients with melanoma resistant to ACT due to antigen downregulation.
