Antifibrotic therapy to normalize the tumor microenvironment

Area of Science:

• Oncology
• Cancer Biology
• Fibrosis Research

Background:

• Tumors often feature fibrotic regions within the tumor microenvironment (TME), characterized by fibroblasts, immune cells, extracellular matrix (ECM), and interstitial fluid.
• An abundant fibrotic TME is linked to poor treatment outcomes in cancer patients.
• Normalizing the TME is a hypothesized strategy to enhance cancer therapy effectiveness.

Purpose of the Study:

• To review and categorize strategies for normalizing the fibrotic TME through targeted antifibrotic therapy.
• To analyze the dual effects of antifibrotic therapies, which can either enhance or impede treatment outcomes.
• To identify promising therapeutic avenues, such as targeting cancer-associated fibroblasts (CAFs) and their signaling pathways.

Main Methods:

• Categorization of antifibrotic approaches into three main strategies: targeting ECM components, targeting CAFs, and targeting CAF-activating signaling pathways.
• Review of agents used for each strategy, including ECM-degrading enzymes (collagenase, hyaluronidase), CAF-eliminating/reprogramming agents, and signaling pathway inhibitors (e.g., losartan targeting TGF-β).
• Analysis of studies reporting conflicting outcomes of antifibrotic therapy, considering factors like CAF subpopulations and treatment parameters.

Main Results:

• Antifibrotic therapy presents a "two-edged sword" with studies showing both enhanced treatment response and increased tumor growth/metastasis.
• Conflicting results may stem from the heterogeneity of CAFs, with some promoting and others inhibiting tumor progression.
• Factors such as disease stage, treatment duration, and induced immune cell recruitment influence antifibrotic therapy outcomes.

Conclusions:

• Targeting the TGF-β signaling pathway, particularly with losartan, shows promise, with observed benefits in pancreatic cancer treatment.
• Further research into the mechanisms of tumor fibrosis is essential for developing safe and effective antifibrotic treatments.
• Understanding CAF heterogeneity is critical for optimizing antifibrotic strategies and improving cancer patient outcomes.