The tumor microenvironment (TME) evolves to support tumor progression. One marker of more aggressive malignancy is hyaluronan (HA) accumulation. Here, we characterize biological and physical changes ...associated with HA-accumulating (HA-high) tumors.
We used immunohistochemistry,
imaging of tumor pH, and microdialysis to characterize the TME of HA-high tumors, including tumor vascular structure, hypoxia, tumor perfusion by doxorubicin, pH, content of collagen. and smooth muscle actin (α-SMA). A novel method was developed to measure real-time tumor-associated soluble cytokines and growth factors. We also evaluated biopsies of murine and pancreatic cancer patients to investigate HA and collagen content, important contributors to drug resistance.
In immunodeficient and immunocompetent mice, increasing tumor HA content is accompanied by increasing collagen content, vascular collapse, hypoxia, and increased metastatic potential, as reflected by increased α-SMA.
treatment of HA-high tumors with PEGylated recombinant human hyaluronidase (PEGPH20) dramatically reversed these changes and depleted stores of VEGF-A165, suggesting that PEGPH20 may also diminish the angiogenic potential of the TME. Finally, we observed in xenografts and in pancreatic cancer patients a coordinated increase in HA and collagen tumor content.
The accumulation of HA in tumors is associated with high tIP, vascular collapse, hypoxia, and drug resistance. These findings may partially explain why more aggressive malignancy is observed in the HA-high phenotype. We have shown that degradation of HA by PEGPH20 partially reverses this phenotype and leads to depletion of tumor-associated VEGF-A165. These results encourage further clinical investigation of PEGPH20.
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Elevated interstitial fluid pressure can present a substantial barrier to drug delivery in solid tumors. This is particularly true of pancreatic ductal adenocarcinoma, a highly lethal disease ...characterized by a robust fibroinflammatory response, widespread vascular collapse, and hypoperfusion that together serve as primary mechanisms of treatment resistance. Free-fluid pressures, however, are relatively low in pancreatic ductal adenocarcinoma and cannot account for the vascular collapse. Indeed, we have shown that the overexpression and deposition in the interstitium of high-molecular-weight hyaluronan (HA) is principally responsible for generating pressures that can reach 100 mmHg through the creation of a large gel-fluid phase. By interrogating a variety of tissues, tumor types, and experimental model systems, we show that an HA-dependent fluid phase contributes substantially to pressures in many solid tumors and has been largely unappreciated heretofore. We investigated the relative contributions of both freely mobile fluid and gel fluid to interstitial fluid pressure by performing simultaneous, real-time fluid-pressure measurements with both the classical wick-in-needle method (to estimate free-fluid pressure) and a piezoelectric pressure catheter transducer (which is capable of capturing pressures associated with either phase). We demonstrate further that systemic treatment with pegylated recombinant hyaluronidase (PEGPH20) depletes interstitial HA and eliminates the gel-fluid phase. This significantly reduces interstitial pressures and leaves primarily free fluid behind, relieving the barrier to drug delivery. These findings argue that quantifying the contributions of free- and gel-fluid phases to hydraulically transmitted pressures in a given cancer will be essential to designing the most appropriate and effective strategies to overcome this important and frequently underestimated resistance mechanism.
Pancreatic ductal adenocarcinoma (PDAC) is characterized by high levels of fibrosis, termed desmoplasia, which is thought to hamper the efficacy of therapeutics treating PDAC. Our primary focus was ...to evaluate differences in the extent of desmoplasia in primary tumors and metastatic lesions. As metastatic burden is a primary cause for mortality in PDAC, the extent of desmoplasia in metastases may help to determine whether desmoplasia targeting therapeutics will benefit patients with late-stage, metastatic disease.
We sought to assess desmoplasia in metastatic lesions of PDAC and compare it with that of primary tumors. Fifty-three patients' primaries and 57 patients' metastases were stained using IHC staining techniques.
We observed a significant negative correlation between patient survival and extracellular matrix deposition in primary tumors. Kaplan-Meier curves for collagen I showed median survival of 14.6 months in low collagen patients, and 6.4 months in high-level patients (log rank, P < 0.05). Low-level hyaluronan patients displayed median survival times of 24.3 months as compared with 9.3 months in high-level patients (log rank, P < 0.05). Our analysis also indicated that extracellular matrix components, such as collagen and hyaluronan, are found in high levels in both primary tumors and metastatic lesions. The difference in the level of desmoplasia between primary tumors and metastatic lesions was not statistically significant.
Our results suggest that both primary tumors and metastases of PDAC have highly fibrotic stroma. Thus, stromal targeting agents have the potential to benefit PDAC patients, even those with metastatic disease.
Receiving the Lasker award for Clinical Medical Research is a staggering event. Perhaps equally staggering is the fact that as many as 2 million women worldwide have now been treated with Herceptin ...(trastuzumab), many of whom benefited from the treatment. This accomplishment is wonderfully rewarding for everyone who has been involved.
Receiving the Lasker award for Clinical Medical Research is a staggering event. Perhaps equally staggering is the fact that as many as 2 million women worldwide have now been treated with Herceptin (trastuzumab), many of whom benefited from the treatment. This accomplishment is wonderfully rewarding for everyone who has been involved.
Hyaluronan (HA) has many functions in the extracellular milieu of normal and diseased tissues. Disease-associated HA accumulation has been shown to predict a worsened prognosis in cancer patients, ...with tumors having a high-extracellular HA content (HA-high) being more aggressive than their HA-low counterparts. HA-high tumor aggressiveness is derived from the specialized biomechanical and molecular properties of the HA-based assembly of HA binding proteins and the growth-promoting factors that accumulate in it. Biophysical characteristics of an HA-high tumor microenvironment include high tumor interstitial pressure, compression of tumor vasculature, and resulting tumor hypoxia. Within the tumor cell membrane, HA receptors, primarily CD44 and RHAMM, anchor the HA-high extracellular network. HA-CD44 association on the tumor cell surface enhances receptor tyrosine kinase activity to drive tumor progression and treatment resistance. Together, malignant cells in this HA-high matrix may evolve dependency on it for growth. This yields the hypothesis that depleting HA in HA-high tumors may be associated with a therapeutic benefit. A pegylated form of recombinant human hyaluronidase PH20 (PEGPH20) has been deployed as a potential cancer therapeutic in HA-high tumors. PEGPH20 can collapse this matrix by degrading the HA-assembled tumor extracellular framework, leading to tumor growth inhibition, preferentially in HA-high tumors. Enzymatic depletion of HA by PEGPH20 results in re-expansion of the tumor vasculature, reduction in tumor hypoxia, and increased penetration of therapeutic molecules into the tumor. Finally, HA-depletion results in reduced signaling via CD44/RHAMM. Taken together, HA-depletion strategies accomplish their antitumor effects by multiple mechanisms that include targeting both biophysical and molecular signaling pathways. Ongoing clinical trials are examining the potential of PEGPH20 in combination with partner therapeutics in several cancers.
Despite tremendous progress in cancer immunotherapy for solid tumors, clinical success of monoclonal antibody (mAb) therapy is often limited by poorly understood mechanisms associated with the tumor ...microenvironment (TME). Accumulation of hyaluronan (HA), a major component of the TME, occurs in many solid tumor types, and is associated with poor prognosis and treatment resistance in multiple malignancies. In this study, we describe that a physical barrier associated with high levels of HA (HA(high)) in the TME restricts antibody and immune cell access to tumors, suggesting a novel mechanism of in vivo resistance to mAb therapy. We determined that approximately 60% of HER2(3+) primary breast tumors and approximately 40% of EGFR(+) head and neck squamous cell carcinomas are HA(high), and hypothesized that HA(high) tumors may be refractory to mAb therapy. We found that the pericellular matrix produced by HA(high) tumor cells inhibited both natural killer (NK) immune cell access to tumor cells and antibody-dependent cell-mediated cytotoxicity (ADCC) in vitro. Depletion of HA by PEGPH20, a pegylated recombinant human PH20 hyaluronidase, resulted in increased NK cell access to HA(high) tumor cells, and greatly enhanced trastuzumab- or cetuximab-dependent ADCC in vitro. Furthermore, PEGPH20 treatment enhanced trastuzumab and NK cell access to HA(high) tumors, resulting in enhanced trastuzumab- and NK cell-mediated tumor growth inhibition in vivo. These results suggest that HA(high) matrix in vivo may form a barrier inhibiting access of both mAb and NK cells, and that PEGPH20 treatment in combination with anticancer mAbs may be an effective adjunctive therapy for HA(high) tumors.
Extracellular adenosine in tumors can suppress immune responses and promote tumor growth. Adenosine deaminase 2 (ADA2) converts adenosine into inosine. The role of ADA2 in cancer and whether it can ...target adenosine for cancer therapy has not been investigated. Here we show that increased ADA2 expression is associated with increased patient survival and enrichment of adaptive immune response pathways in several solid tumor types. Several ADA2 variants were created to improve catalytic efficiency, and PEGylation was used to prolong systemic exposure. In mice, PEGylated ADA2 (PEGADA2) inhibited tumor growth by targeting adenosine in an enzyme activity-dependent manner and thereby modulating immune responses. These findings introduce endogenous ADA2 expression as a prognostic factor and PEGADA2 as a novel immunotherapy for cancer. SIGNIFICANCE: This study identifies ADA2 as a prognostic factor associated with prolonged cancer patient survival and introduces the potential of enzymatic removal of adenosine with engineered ADA2 for cancer immunotherapy.
Monoclonal antibody therapeutics have been approved for over 30 targets and diseases, most commonly cancer. Antibodies have become the new backbone of the pharmaceutical industry, which previously ...relied on small molecules. Compared with small molecules, monoclonal antibodies (mAbs) have exquisite target selectivity and hence less toxicity as a result of binding other targets. The clinical value of both mAbs and ligand traps has been proven. New applications of mAbs are being tested and mAbs have now been designed to target two (bi-specific, eg TNF-α and IL-17) or more targets simultaneously, augmenting their therapeutic potential. Because of space limitations and the wide ranging scope of this review there are regrettably, but inevitably, omissions and missing citations. We have chosen to highlight the first successes in inflammatory diseases and cancer, but a broader overview of approved mAbs and related molecules can be found in Table 1.
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