The growth of a xenograft breast cancer tumor model with engineered hyaluronan-accumulating stroma is dependent on hyaluronan and independent of CD44

Hyaluronan accumulation in the tumor microenvironment is associated with poor prognosis in several solid human cancers. To understand the role of stromal hyaluronan in tumor progression, we engineered 3T3HAS3, a hyaluronan-producing fibroblast cell line, by lentiviral transduction of Balb/c 3T3 cells with the human hyaluronan synthase 3(HAS3) gene. 3T3HAS3 cells significantly enhanced tumor growth when co-grafted with MDA-MB-468 cells in nude mice. Immunohistochemical analysis of the xenograft tumors showed that MDA-MB-468 cells were surrounded by hyaluronan-accumulating stroma, closely resembling the morphology observed in human breast cancer specimens. Tumor growth of MDA-MB-468 + 3T3HAS3 co-grafts was greatly reduced upon hyaluronan degradation by lentiviral transduction of a human hyaluronidase gene in 3T3HAS3 cells, or by systemic administration of pegvorhyaluronidase alfa (PEGPH20). In contrast, the growth of the co-graft tumors was not inhibited when CD44 expression was reduced or ablated by small hairpin RNA-mediated CD44 knockdown in MDA-MB-468 cells, CD44 CRISPR knockout in 3T3HAS3 cells, or by grafting these cells in CD44 knockout nude mice. Collectively, these data demonstrate that tumor growth of an engineered xenograft breast cancer model with hyaluronan-accumulating stroma can be dependent on hyaluronan and independent of CD44.

Abstract A46: Hyaluronan-dependent growth of human triple negative breast cancer MDA-MB-468 in a mouse xenograft model with HA-high stroma

Hyaluronan (also known as hyaluronic acid or HA) is a megadalton sized glycosaminoglycan present in the extracellular matrix. The abnormal accumulation of HA in the solid tumor microenvironment (TME) of several human cancers, including pancreatic, breast, colon and prostate, has been well studied and is associated with poor prognosis. In certain breast cancer specimens with a HA-high status, HA is found to be significantly associated with the stromal compartment rather than with tumor cells. To understand the interaction between tumor cells and a HA containing stromal compartment, we engineered a HA-high stromal cell line by lentiviral transduction of the human HAS3 gene into Balb/c 3T3 fibroblast cells. The 3T3/HAS3 cells produced significant amounts of HA in vitro, which was shown to bind to the HA-low/CD44-high breast cancer cell line MDA-MB-468 at the cell surface. When co-grafted with MDA-MB-468 cells in mice, 3T3/HAS3 cells promoted the in vivo growth of MDA-MB-468 cells. Immunohistochemical analysis of tumor xenograft samples showed that MDA-MB-468 cells were surrounded by HA-high stromal cells, closely resembling the tumor morphology observed in human breast cancer specimens. Tumor growth in this co-grafting model was highly dependent on the presence of 3T3/HAS3 cells, and required HA produced by 3T3/HAS3 cells. Ganciclovir blocked the growth of MDA-MB-468 co-inoculated with 3T3/HAS3/hsv-TK, as did HA removal either by the expression of the HA degrading enzyme PH20, directly in 3T3/HAS3 cells or by exogenous administration of PEGPH20, a pegylated version of PH20 engineered for extended half-life. Interestingly, the presence of 3T3/HAS3 cells was found to be most critical during early stages of tumor progression and was non-essential for tumor maintenance once tumors were fully established, as ganciclovir had little impact on tumor growth when tumor size was larger than 500 mm3 but prevented tumor growth when administered at inoculation and inhibited tumor growth when treatment started at a smaller tumor size (200 mm3, 90.4% TGI). We have developed a tumor xenograft model that mimics breast cancer with a HA-high status in the tumor stromal compartment. Further characterization of this model will provide insight into the mechanisms by which increased levels of HA and the associated changes in the TME promote disease progression in breast cancer.

Citation Format: Chunmei Zhao, Mathieu Marella, Lei Huang, Anne Kultti, Susan Zimmerman, Caroline EN Chou, Jesse Bahn, Adrian Radi, Zhongdong Huang, H Michael Shepard, Christopher D. Thanos. Hyaluronan-dependent growth of human triple negative breast cancer MDA-MB-468 in a mouse xenograft model with HA-high stroma. [abstract]. In: Proceedings of the AACR Special Conference: Function of Tumor Microenvironment in Cancer Progression; 2016 Jan 7–10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2016;76(15 Suppl):Abstract nr A46.

Abstract 1217: Preclinical evaluation of a next-generation, EGFR targeting ADC that promotes regression in KRAS or BRAF mutant tumors

Cancers with downstream activating KRAS or BRAF mutations in the EGFR pathway are resistant to EGFR targeting agents such as cetuximab and correspond to a significant unmet need. We hypothesized that an anti-EGFR ADC could be effective against KRAS or BRAF mutated tumors due to the cytotoxic mechanism of the ADC warhead. In an effort to eliminate the known dermal toxicity associated with anti-EGFR therapy, and to mitigate potential toxicities associated with treatment by an anti-EGFR ADC, a mAb was engineered with increased tumor microenvironment (TME) specificity for EGFR. The lead mAb demonstrated undetectable in vivo binding to human donor foreskins grafted onto nude mice, while binding to human A431 tumor xenografts with similar intensity to cetuximab (P < 0.005, detected using DyLight-755 conjugated versions of each mAb, measured with a Caliper IVIS system). The lead mAb was further optimized and conjugated to the potent cytotoxic drug MMAE using a novel bis-alkylating conjugation linker, which covalently re-bridged the inter-chain disulfide bonds, creating a stable and defined ADC. The resulting ADC, HTI-1511, incorporated a vc-PAB cleavable moiety and a short linear PEG (24 ethylene glycol units) in a side-chain configuration. Analytical HIC revealed that HTI-1511 possessed a nearly homogenous drug:antibody ratio (DAR) of 4 (>99.7%). Approximately 70% of this compound was rapidly internalized by human tumor cells grown in vitro over 4 hours, overlapping the internalization kinetics of the unconjugated mAb. HTI-1511 was evaluated for efficacy against two human EGFR overexpressing tumor models, MDA-MB-231M (triple-negative breast cancer, KRAS-G13D) and HT-29 (colorectal cancer, BRAF-V600E), and dosed at 5, 10, and 15 mg/kg, (qw, IV). A clear dose dependent anti-tumor response was observed with complete tumor regressions observed at the 15 mg/kg dose in both models, which were resistant to treatment by cetuximab. In addition, HTI-1511 was well-tolerated at 2 and 8 mg/kg in a cynomolgus monkey toxicity study (n = 3 per group), with limited dermal findings that were comparable with the vehicle control group. No adverse findings were observed at either dose. HTI-1511 showed a high degree of circulating stability in cynomolgus monkeys, and lacked in vivo degradation and instability that was observed in a control ADC conjugated using maleimide chemistry. HTI-1511 demonstrated significantly attenuated binding to FcγRIIa, FcγIIb, FcγIIIa 158V, and FcγIIIa 158F receptors, but not attenuated binding to FcγR1, in a FACS based assay format specific for each receptor, suggesting that HTI-1511 might have improved tolerability due to lack of binding by FcγRII-III receptors, possibly due steric hindrance from the PEG side chain. Thus, HTI-1511 holds promise as a potentially safe and effective treatment of EGFR overexpressing tumors with KRAS or BRAF mutations.

Citation Format: Lei Huang, Bob Veneziale, Mark Frigerio, George Badescu, Xiaoming Li, Qiping Zhao, Jesse Bahn, Jennifer Souratha, Ryan Osgood, Chunmei Zhao, Kim Phan, Jessica Cowell, Sanna Rosengren, Jason Parise, Martin Pabst, Mathew Bird, William McDowell, Gina Wei, Curtis Thompson, Antony Godwin, Michael Shepard, Christopher Thanos. Preclinical evaluation of a next-generation, EGFR targeting ADC that promotes regression in KRAS or BRAF mutant tumors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1217.

Abstract 982: Hyaluronan (HA) depletion increases tumor accessibility of T cell and therapeutic PD-L1 monoclonal antibody in HAhigh tumors

Tumor initiation and progression is a complex interaction between host and tumor. One of the essential elements for tumor progression is evasion of the host immune system. Among the mechanisms important for host immune cell evasion is the amplification of receptor tyrosine kinases, and tumor secretion of immune suppressive cytokines, like TGF-β, suppression of activated T cells by various intrinsic immune response regulatory mechanisms 1-3. Additionally, tumor cells evolve to express cell-associated programmed death 1 (PD1) ligands (PD-L1 or LD-L2), which promotes tumor cell growth by inactivating PD1 expressing activated T cells 3-4. Recent reports suggest a role of the tumor microenvironment (TME) as an immunosuppressive environment by accumulating hyaluronan (HA)5-7, which then results in accumulation of water and resulting high interstitial fluid pressure and sequelae, including blood vessel compression, and decreased perfusion8-10. Hyaluronan depletion from solid tumors with high levels of HA (HAhigh) reverses these physiological effects, resulting in increased chemotherapeutic drug penetration and tumor growth inhibition in preclinical animal models 8-10. In this report we investigated whether increasing the access of therapeutic immune checkpoint monoclonal antibodies and effector T cells into the HAhigh tumor can enhance activated T cell-mediated tumor cell lysis. We have generated human hyaluronan synthase and PD-L1 overexpressing tumor cell lines to study (i) the role of HA in PD-1 and PD-L1 interaction in HAhigh tumor cells, and (ii) whether HA depletion increases the efficacy of tumor cell killing by PD-1 positive cytotoxic T lymphocytes in the presence of PD-L1 blocking monoclonal antibody. Our data show that HAhigh tumor cells form an HA-rich barrier that restricts T cell access to tumor cell and HA depletion by PEGPH20, a pegylated PH20, allowed T cells to access tumor cell. HA depletion increases HAhigh PD-L1 positive tumor cells killing by activated T cell in the presence of anti-human PD-L1 monoclonal antibody (MAb). Furthermore, HA depletion by PEGPH20 increased the access of T cell and anti-human PD-L1 MAb in HAhigh xenograft tumors, suggesting that PEGPH20 may enhance efficacy of immune check point blocking therapeutic PD-L1 MAb in HAhigh tumors.

References:

1. Rabinovich et al. Annu Rev Immunol., 2007;25:267-96.

2. Hudzika et al. Cell Growth Differ. 1990; 1:129-34.

3. Quezada et al. British Journal of Cancer, 2013; 108: 1560-1565.

4. Zou et al. Nature Reviews Immunology, 2008; 8: 467-477.

5. Sironen et al. Exp Cell Res 2011;317:383-91.

6. Kultti et al. Cancers 2012;4:873-903.

7. Tlsty et al. Annu Rev Pathol 2006;1:119-50.

8. Thompson et al. Mol Cancer Ther 2010;9:3052-64.

9. Jacobetz et al. Gut 2013;62:112-20.

10. Provenzano et al. Cancer Cell 2012;21:418-29.

Citation Format: Netai C. Singha, Chunmei Zhao, Jesse Bahn, Adrian Radi, H. Michael Shepard, Zhongdong Huang. Hyaluronan (HA) depletion increases tumor accessibility of T cell and therapeutic PD-L1 monoclonal antibody in HAhigh tumors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 982. doi:10.1158/1538-7445.AM2015-982

Melanoma induction by ultraviolet A but not ultraviolet B radiation requires melanin pigment

Malignant melanoma of the skin (CMM) is associated with ultraviolet radiation exposure, but the mechanisms and even the wavelengths responsible are unclear. Here we use a mammalian model to investigate melanoma formed in response to precise spectrally defined ultraviolet wavelengths and biologically relevant doses. We show that melanoma induction by ultraviolet A (320-400 nm) requires the presence of melanin pigment and is associated with oxidative DNA damage within melanocytes. In contrast, ultraviolet B radiation (280-320 nm) initiates melanoma in a pigment-independent manner associated with direct ultraviolet B DNA damage. Thus, we identified two ultraviolet wavelength-dependent pathways for the induction of CMM and describe an unexpected and significant role for melanin within the melanocyte in melanomagenesis.

Abstract 2265: Expression of hyaluronan in human cancer tissue: A predictive biomarker for PEGPH20-mediated therapy

Background: Hyaluronan (HA), a ubiquitous, high-molecular-mass polysaccharide in the precellular and extracellular matrix, is frequently elevated in malignancy, and associated with aggressive disease. Interaction of HA and tumor cells may activate receptor tyrosine kinases, enhance drug resistance, and facilitate tumor progression. A pegylated recombinant human PH20 hyaluronidase (PEGPH20) has been developed to systemically target tumors that accumulated with HA. Systemic PEGPH20 administration in mice bearing PC3 tumors induced a decrease in tumor interstitial fluid pressure (IFP), a decrease in tumor water content, and an increase in tumor vascular volume by enzymatically depleting the HA from the extracellular tumor microenvironment and resulted in significant tumor growth inhibition. PEGPH20 therefore represents an innovative potential treatment approach that may provide improved therapeutic outcomes for cancer patients.

Methods: The present study investigated the expression of HA in paraffin embedded human tissue from 9 tumor types as well as corresponding normal tissue by immunohistochemical staining of BioMax tissue arrays with biotinylated HA binding protein (HABP) as a probe. Staining intensity was quantified using Aperio Spectrum plus software. The correlation between HA expression and PEGPH20 response has also been explored using established preclinical models.

Results: Strong HA expression was found in 87% of pancreatic, 64% of breast, 50% of multiple myeloma, 46% of NSCLC, 39% of gastric, and 22% of prostate cancer tissues, when compared with corresponding normal tissue (p<0.05). BxPc3 (HA high), MIA PaCa-2 (HA low) and AsPC-1 (HAlow) pancreatic tumor xenografts were evaluated for tumor growth inhibition (TGI) after systemic PEGPH20 treatment and TGI's of 25%, 9% and 15% were observed respectively. In addition, 3 prostate cancers, PC3 (HA high), MatLylu (HA high) and Du145 (HA low) were also evaluated in xenografts with significant growth inhibition shown for PC3 (72%) and MatLylu (34%). Systemic PEGPH20 treatment also induced tumor growth inhibition (60%) for 4T1 (HA high) breast cancer.

Conclusion: Accumulation of HA compared to normal tissue was commonly observed and most frequent in pancreatic adenocarcinomas (87%). Furthermore, accumulation of HA was shown to predict response to PEGPH20 therapy in xenograft models (R2=0.805, p<0.01). This work provides strong rationale for exploring efficacy of PEGPH20 in clinical trials.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2265.