American Association for Cancer Research
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FIGURE 5 from Mechanistic Characterization of Cancer-associated Fibroblast Depletion via an Antibody–Drug Conjugate Targeting Fibroblast Activation Protein

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posted on 2024-06-12, 14:20 authored by Joseph P. Gallant, Hallie M. Hintz, Gihan S. Gunaratne, Matthew T. Breneman, Emma E. Recchia, Jayden L. West, Kendahl L. Ott, Erika Heninger, Abigail E. Jackson, Natalie Y. Luo, Zachary T. Rosenkrans, Reinier Hernandez, Shuang G. Zhao, Joshua M. Lang, Labros Meimetis, David Kosoff, Aaron M. LeBeau

Downstream effects of huB12-MMAE treatment on gene expression in CAF-tumor models in Stacks. A, Concentration of selected factors in supernatant in monoculture and coculture conditions. B, Relative mRNA expression of select genes in hPrCSC-44 cells in monoculture and coculture treated and untreated conditions. C, Relative mRNA expression of select genes in 22Rv1 cells in monoculture and coculture treated and untreated conditions. Data for B and C expressed as normalized relative quantity (NRQ). *, P < 0.05.

Funding

HHS | National Institutes of Health (NIH)

Prostate Cancer Foundation (PCF)

Randy Shaver Cancer Research and Community Fund (Randy Shaver Cancer Research & Community Fund)

U.S. Department of Veterans Affairs (VA)

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ARTICLE ABSTRACT

Cancer-associated fibroblasts (CAF) are a prominent cell type within the tumor microenvironment (TME) where they are known to promote cancer cell growth and survival, angiogenesis, drug resistance, and immunosuppression. The transmembrane prolyl protease fibroblast activation protein (FAP) is expressed on the surface of highly protumorigenic CAFs found in the stroma of nearly every cancer of epithelial origin. The widespread expression of FAP has made it an attractive therapeutic target based on the underlying hypothesis that eliminating protumorigenic CAFs will disrupt the cross-talk between components of TME resulting in cancer cell death and immune infiltration. This hypothesis, however, has never been directly proven. To eliminate FAP-expressing CAFs, we developed an antibody–drug conjugate using our anti-FAP antibody, huB12, coupled to a monomethyl auristatin E (huB12-MMAE) payload. After determining that huB12 was an effective targeting vector, we found that huB12-MMAE potently eliminated FAP-expressing cells as monocultures in vitro and significantly prolonged survival in vivo using a xenograft engineered to overexpress FAP. We investigated the effects of selectively eliminating CAFs using a layered, open microfluidic cell coculture platform, known as the Stacks. Analysis of mRNA and protein expression found that treatment with huB12-MMAE resulted in the increased secretion of the proinflammatory cytokines IL6 and IL8 by CAFs and an associated increase in expression of proinflammatory genes in cancer cells. We also detected increased secretion of CSF1, a cytokine involved in myeloid recruitment and differentiation. Our findings suggest that the mechanism of FAP-targeted therapies is through effects on the immune microenvironment and antitumor immune response. The direct elimination of FAP-expressing CAFs disrupts the cross-talk with cancer cells leading to a proinflammatory response and alterations in the immune microenvironment and antitumor immune response.