Pan-lysyl oxidase inhibition disrupts fibroinflammatory tumor stroma, rendering cholangiocarcinoma susceptible to chemotherapy.

Background: Cholangiocarcinoma (CCA) features highly desmoplastic stroma that promotes structural and functional resistance to therapy. Lysyl oxidases (LOX, LOXL1-4) catalyze collagen cross-linking, thereby increasing stromal rigidity and facilitating therapeutic resistance. Here, we evaluate the role of lysyl oxidases in stromal desmoplasia and the effects of pan-lysyl oxidase (pan-LOX) inhibition in CCA.

Methods: Resected CCA and normal liver specimens were analyzed from archival tissues. Spontaneous and orthotopic murine models of intrahepatic CCA (iCCA) were used to assess the impact of the pan-LOX inhibitor PXS-5505 in treatment and correlative studies. The functional role of pan-LOX inhibition was interrogated through in vivo and ex vivo assays.

Results: All 5 lysyl oxidases are upregulated in CCA and reduced lysyl oxidase expression is correlated with an improved prognosis in resected patients with CCA. Spontaneous and orthotopic murine models of intrahepatic cholangiocarcinoma upregulate all 5 lysyl oxidase isoforms. Pan-LOX inhibition reversed mechanical compression of tumor vasculature, resulting in improved chemotherapeutic penetrance and cytotoxic efficacy. The combination of chemotherapy with pan-LOX inhibition increased damage-associated molecular pattern release, which was associated with improved antitumor T-cell responses. Pan-LOX inhibition downregulated macrophage invasive signatures in vitro, rendering tumor-associated macrophages more susceptible to chemotherapy. Mice bearing orthotopic and spontaneously occurring intrahepatic cholangiocarcinoma tumors exhibited delayed tumor growth and improved survival following a combination of pan-LOX inhibition with chemotherapy.

Conclusions: CCA upregulates all 5 lysyl oxidase isoforms, and pan-LOX inhibition reverses tumor-induced mechanical forces associated with chemotherapy resistance to improve chemotherapeutic efficacy and reprogram antitumor immune responses. Thus, combination therapy with pan-LOX inhibition represents an innovative therapeutic strategy in CCA.