Dual Blockade of CD44v6 and PI3K Undermines Colorectal Cancer Stem Cell Reprogramming

Colorectal cancer often evades treatment not through a single mutation but through a dynamic process of adaptation: tumor cells rewire their identity in response to signals from their surroundings, giving rise to drug-tolerant populations that survive therapy and later drive relapse. A new study published in Cell Death Discovery points to a specific molecular partnership behind this plasticity, and argues that blocking it may require hitting two targets at once rather than one.

The research, led by Kimiya Shams and Simone Di Franco with colleagues in Italy and abroad, focuses on colorectal cancer stem cells, the self-renewing subpopulation thought to seed tumor growth and regeneration after treatment. The team reports that cytokines released by tumor-associated cells in the microenvironment, most notably hepatocyte growth factor (HGF), set off a cascade in which the c-Met receptor is phosphorylated and the variant surface marker CD44v6 is upregulated. This signaling boosts the clonogenic capacity of the cancer cells, expanding the stem-like pool and pushing it toward a hybrid epithelial-mesenchymal state, a transcriptional program associated with both increased resistance to therapy and greater metastatic potential.

At the center of the study is AMC303, described by the authors as a highly selective inhibitor of CD44v6. On its own, however, the inhibitor proved insufficient under microenvironmental pressure. In mouse avatars of colorectal cancer built from patient-derived cancer stem cells, HGF continued to drive phenotypic reprogramming even when canonical CD44v6/c-Met signaling was blocked by AMC303. According to the findings, the cells compensated by routing their signals through c-Met co-receptors and downstream PI3K/AKT and MAPK pathways, effectively bypassing the blockade.

That observation shaped the therapeutic logic of the paper. When the researchers added Apitolisib, a dual PI3K/mTOR inhibitor, the compensatory PI3K/AKT and MAPK signaling was suppressed. In the combination setting, the proliferation rate of the cancer cells dropped, and the cells became more vulnerable to standard chemotherapeutic regimens in vitro. The authors frame this as a way of preventing or reversing therapeutic adaptive resistance and disease progression under tumor microenvironmental cues, rather than simply attacking the tumor cells in isolation.

The study’s significance lies in how it reframes resistance. Rather than treating drug tolerance as a fixed property of certain clones, the work portrays it as an induced, environment-dependent state: the microenvironment actively instructs cancer cells to reprogram, and any single-agent strategy that leaves those environmental signals unopposed invites escape through parallel pathways. The combination of a CD44v6 inhibitor with a PI3K/mTOR inhibitor is presented as a rational answer to that redundancy, targeting the reprogramming machinery itself.

The evidence, however, remains preclinical. The key mechanistic findings come from in vitro systems and from mouse avatars of colorectal cancer stem cells, and the enhanced chemotherapeutic sensitivity was measured under in vitro exposure. The abstract does not report clinical trial data, and the published version is flagged as an early-share, peer-reviewed accepted manuscript that is still subject to further edits before the final Version of Record. Translating the strategy into patients would require demonstrating that the combination is tolerable and effective in human tumors, whose microenvironments are more complex than the models used here.

Even so, the study adds to a growing body of work suggesting that durable control of colorectal cancer may depend on anticipating how tumors adapt rather than reacting to resistance after it emerges. By identifying HGF-driven, CD44v6-associated reprogramming as a driver of stem-like expansion and hybrid EMT identity, and by showing that PI3K/AKT and MAPK signaling can compensate when the canonical axis is blocked, the researchers offer a mechanistic map of one route tumors take around targeted therapy. The findings support further investigation of combination approaches that pair CD44v6 inhibition with suppression of downstream survival pathways as a means of limiting adaptive therapeutic escape in colorectal cancer.

Subject of Research: HGF-driven reprogramming of colorectal cancer stem cells and its disruption by combined CD44v6 and PI3K/mTOR inhibition

Article Title: Targeting CD44v6 and PI3K disrupts HGF-driven reprogramming of colorectal cancer stem cells

Article References: Shams, K., Verona, F., Brancato, O. R., Di Bella, S., Di Miceli, N., D’Accardo, C., Porcelli, G., Mangiapane, L. R., Bianca, P., Clauzon, L., Orilio, F., Pillitteri, I., Pantina, V. D., Gaggianesi, M., Modica, C., Turdo, A., Veschi, V., Todaro, M., Dembowsky, K., … Di Franco, S. (2026). Targeting CD44v6 and PI3K disrupts HGF-driven reprogramming of colorectal cancer stem cells. Cell Death Discovery. https://doi.org/10.1038/s41420-026-03408-0

Image Credits: AI Generated

DOI: 10.1038/s41420-026-03408-0

Keywords: colorectal cancer, cancer stem cells, CD44v6, HGF, c-Met, PI3K/mTOR inhibitor, AMC303, Apitolisib, EMT plasticity, drug resistance, tumor microenvironment, preclinical study