SGN-LIV1A: a novel antibody-drug conjugate targeting LIV-1 for the treatment of metastatic breast cancer

In this article, we describe a novel antibody-drug conjugate (ADC; SGN-LIV1A), targeting the zinc transporter LIV-1 (SLC39A6) for the treatment of metastatic breast cancer. LIV-1 was previously known to be expressed by estrogen receptor-positive breast cancers. In this study, we show that LIV-1 expression is maintained after hormonal therapy in primary and metastatic sites and is also upregulated in triple-negative breast cancers. In addition to breast cancer, other indications showing LIV-1 expression include melanoma, prostate, ovarian, and uterine cancer. SGN-LIV1A consists of a humanized antibody conjugated through a proteolytically cleavable linker to monomethyl auristatin E, a potent microtubule-disrupting agent. When bound to surface-expressed LIV-1 on immortalized cell lines, this ADC is internalized and traffics to the lysozome. SGN-LIV1A displays specific in vitro cytotoxic activity against LIV-1-expressing cancer cells. In vitro results are recapitulated in vivo where antitumor activity is demonstrated in tumor models of breast and cervical cancer lineages. These results support the clinical evaluation of SGN-LIV1A as a novel therapeutic agent for patients with LIV-1-expressing cancer.

Abstract 3962: SGN-LIV1A: a development stage antibody drug-conjugate targeting LIV-1 for the treatment of metastatic breast cancer

LIV-1, also known as SLC39A6 or ZIP6, is a member of the zinc transporter family and was first identified as an estrogen-inducible gene in breast cancer derived cell lines. LIV-1, as a downstream target of STAT3, promotes the epithelial to mesenchymal transition that is important in the malignant progression to metastasis. Consistent with its role in cancer, we determined by immunohistochemical (IHC) analysis that LIV-1 is expressed in subtypes of metastatic breast cancers (ER+/HER2-, HER2+ and triple negative). In healthy human tissues, LIV-1 expression is limited to four hormonally-regulated organs. The broad expression of LIV-1 in metastatic breast cancer in combination with the limited expression in vital organs makes LIV-1 an excellent target for an antibody-drug conjugate (ADC). SGN-LIV1A is an ADC consisting of a humanized anti-LIV-1 mAb conjugated to the microtubule-disrupting agent, monomethyl auristatin E, via a protease-cleavable linker. In vitro, SGN-LIV1A shows target specific internalization and cytotoxic activity against a breast cancer cell line. In vivo studies also demonstrate antitumor activity of SGN-LIV1A in preclinical xenograft models with significant delay of tumor growth compared to control groups. These findings support further evaluation and development of SGN-LIVA as a therapeutic for the treatment of metastatic breast cancer.

Citation Format: Django Sussman, Leia M. Smith, Martha E. Anderson, Steve Duniho, Joshua H. Hunter, Heather Kostner, Jamie B. Miyamoto, Albina Nesterova, Lori Westendorf, Heather A. Van Epps, Nancy Whiting, Dennis R. Benjamin. SGN-LIV1A: a development stage antibody drug-conjugate targeting LIV-1 for the treatment of metastatic breast cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3962. doi:10.1158/1538-7445.AM2013-3962

Abstract 2590: Preclinical evaluation of ASG-5ME, a novel antibody-drug conjugate for pancreatic cancer

Antibody-drug conjugates (ADCs) have demonstrated promising activity and tolerability profiles in oncology clinical trials, including for Hodgkin lymphoma (brentuzumab vedotin) and breast cancer (trastuzumab-DM1), motivating the development of new ADCs targeting antigens in other prevalent cancers. An immunohistochemical survey of expression of the novel tumor antigen AGS-5 revealed strong staining in 90% of pancreatic cancer specimens tested. Importantly, this staining was largely uniform, with essentially all transformed cells demonstrating membranous staining. This observation along with the observation of equally abundant expression of AGS-5 in prostate and other cancers motivated the development of ASG-5ME, an ADC targeting AGS-5. The ADC is comprised of a fully human IgG2 monoclonal antibody conjugated to the potent tubulin-binding drug monomethylauristatin E, conjugated with an average of 3.7 drug molecules per antibody. Conjugation and analysis of this IgG2 ADC will be discussed. The resulting conjugate demonstrated antigen-dependent internalization and in vitro cytotoxicity at sub-saturating ADC concentrations, as well as potent in vivo antitumor activity in patient-derived xenograft models of pancreatic cancer. ASG-5ME has a long (12 day) T1/2 in mice. Taken together, these results support the clinical evaluation of ASG-5ME for treatment of pancreatic cancer

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 2590.

Blocking of CD27-CD70 pathway by anti-CD70 antibody ameliorates joint disease in murine collagen-induced arthritis

Rheumatoid arthritis (RA) is characterized by inflammation and cellular proliferation in the synovial lining of joints that result in cartilage and bone destruction. Although the etiology of RA is unclear, activated lymphocytes and proinflammatory molecules, in particular TNF superfamily members, have been implicated in the disease pathology. A TNF superfamily member, CD70, is found on activated lymphocytes and shown to be important in memory and effector responses of lymphocytes. CD70 is expressed at high levels on chronically activated T cells in patients with autoimmune disorders, including RA. The involvement of CD70 in the progression of RA, however, remains unknown. In this study, we report effects of targeting CD70 on disease pathogenesis by using an anti-mouse CD70 Ab in a murine model of collagen-induced arthritis (CIA). In addition to blocking CD70 binding to its receptor CD27, the anti-CD70 Ab used also engages Fc-dependent effector functions including Ab-dependent cellular cytotoxicity, phagocytosis, and complement fixation. Treatment of mice with anti-CD70 Ab both before the onset or after the established disease in CIA model resulted in marked improvements in disease severity and significant reduction in the production of autoantibodies. Histopathological analyses of the joints of mice revealed a substantial reduction of inflammation, and bone and cartilage destruction in response to the anti-CD70 Ab treatment. These results uncover a novel role for CD27-CD70 interactions in the regulation of in vivo inflammatory response leading to arthritis, and provide a molecular basis to support the rationale for anti-CD70 therapy for autoimmune and inflammatory diseases.

Pulmonary gene expression profiling of inhaled ricin

Aerosol exposure to ricin causes irreversible pathological changes of the respiratory tract resulting in epithelial necrosis, pulmonary edema and ultimately death. The pulmonary genomic profile of BALB/c mice inhalationally exposed to a lethal dose of ricin was examined using cDNA arrays. The expression profile of 1178 mRNA species was determined for ricin-exposed lung tissue, in which 34 genes had statistically significant changes in gene expression. Transcripts identified by the assay included those that facilitate tissue healing (early growth response gene (egr)-1), regulate inflammation (interleukin (IL)-6, tristetraproline (ttp)), cell growth (c-myc, cytokine-inducible SH2-containing protein (cish)- 3), apoptosis (T-cell death associated protein (tdag)51, pim-1) and DNA repair (ephrin type A receptor 2 (ephA2)). Manipulation of these gene products may provide a means of limiting the severe lung damage occurring at the cellular level. Transcriptional activation of egr-1, cish-3, c-myc and thrombospondin (tsp)-1 was already apparent when pathological and physiological changes were observed in the lungs at 12 h postexposure. These genes may well serve as markers for ricin-induced pulmonary toxicity. Ongoing studies are evaluating this aspect of the array data and the potential of several genes for clinical intervention.

A subependymal giant cell astrocytoma in a cat

A 6-year-old spayed female Domestic Shorthair cat presented with a 1 to 2-month history of blindness and altered behavior. At necropsy, a 1-cm-diameter, firm white mass was found arising from the subependymal region of the right lateral ventricular wall that protruded into and partially filled the lumen. Histologically, there was a well-demarcated, expansile paraventricular neoplasm composed of moderately pleomorphic cells within a richly fibrillar matrix arranged in interlacing streams and perivascular pseudorosette-like patterns. Neoplastic cells varied in morphology from small spindloid cells to larger polygonal cells with eccentric vesicular nuclei to neuronlike cells with vesicular nuclei and prominent nucleoli. The mitotic index was low. Immunohistochemically, neoplastic cells were positive for S-100 protein, glial fibrillary acidic protein, and neuron-specific enolase and negative for neurofilament protein. Ultrastructurally, the cells contained few to abundant bundles of intermediate filaments with variable numbers of mitochondria, endoplasmic reticulum, and ribosomes. These features are characteristic of subependymal giant cell astrocytoma (SEGA) in humans. To our knowledge, this is the first reported case of SEGA in domestic animals.