The Antibody Society's antibody validation webinar series.

In the wake of the reproducibility crisis and numerous discussions on how commercially available antibodies as research tool contribute to it, The Antibody Society developed a series of 10 webinars to address the issues involved. The webinars were delivered by speakers with both academic and commercial backgrounds. This report highlights the problems, and offers solutions to help the scientific community appropriately identify the right antibodies and to validate them for their research and development projects. Despite the various solutions proposed here, they must be applied on a case-by-case basis. Each antibody must be verified based on the content of the product sheet, and subsequently through experimentation to confirm integrity, specificity and selectivity. Verification needs to focus on the precise application and tissue/cell type for which the antibody will be used, and all verification data must be reported openly. The various approaches discussed here all have caveats, so a combination of solutions must be considered.

The path to VICTORy - a beginner's guide to success using commercial research antibodies.

Commercial research antibodies are crucial tools in modern cell biology and biochemistry. In the USA some $2 billion a year are spent on them, but many are apparently not fit-for-purpose, and this may contribute to the 'reproducibility crisis' in biological sciences. Inadequate antibody validation and characterization, lack of user awareness, and occasional incompetence amongst suppliers have had immense scientific and personal costs. In this Opinion, I suggest some paths to make the use of these vital tools more successful. I have attempted to summarize and extend expert views from the literature to suggest that sustained routine efforts should made in: (1) the validation of antibodies, (2) their identification, (3) communication and controls, (4) the training of potential users, (5) the transparency of original equipment manufacturer (OEM) marketing agreements, and (5) in a more widespread use of recombinant antibodies (together denoted the 'VICTOR' approach).

The antibody horror show: an introductory guide for the perplexed.

The biological literature reverberates with the inadequacies of commercial research-tool antibodies. The scientific community spends some $2 billion per year on such reagents. Excellent accessible scientific platforms exist for reliably making, validating and using antibodies, yet the laboratory end-user reality is somehow depressing - because they often "don't work". This experience is due to a bizarre and variegated spectrum of causes including: inadequately identified antibodies; inappropriate user and supplier validation; poor user training; and overloaded publishers. Colourful as this may appear, the outcomes for the community are uniformly grim, including badly damaged scientific careers, wasted public funding, and contaminated literature. As antibodies are amongst the most important of everyday reagents in cell biology and biochemistry, I have tried here to gently suggest a few possible solutions, including: a move towards using recombinant antibodies; obligatory unique identification of antibodies, their immunogens, and their producers; centralized international banking of standard antibodies and their ligands; routine, accessible open-source documentation of user experience with antibodies; and antibody-user certification.

The 3rd Antibody Validation meeting: Bath UK 20-21 st September 2018.

The International Antibody Validation meetings offer a welcome British forum for discussing this important topic, which is existentially crucial for the biological sciences community. Now in its 6th year, the biennial meeting is organized by Andrew Chalmers (University of Bath; CiteAb), this year with Carly Dix (Astra Zeneca).  The organizers gathered some 100 members of industry and academia, producers and users, for a day and a half to describe their efforts to ensure that their antibodies have the desired specificity and selectively for well-defined molecular targets. The meeting is largely available as WebCasts ( http://www.antibodyvalidation.co.uk/past-events/2018).

Integrins as Therapeutic Targets: Successes and Cancers.

Integrins are transmembrane receptors that are central to the biology of many human pathologies. Classically mediating cell-extracellular matrix and cell-cell interaction, and with an emerging role as local activators of TGFß, they influence cancer, fibrosis, thrombosis and inflammation. Their ligand binding and some regulatory sites are extracellular and sensitive to pharmacological intervention, as proven by the clinical success of seven drugs targeting them. The six drugs on the market in 2016 generated revenues of some US$3.5 billion, mainly from inhibitors of α4-series integrins. In this review we examine the current developments in integrin therapeutics, especially in cancer, and comment on the health economic implications of these developments.

Cilengitide in newly diagnosed glioblastoma: biomarker expression and outcome.

Integrins αvß3 and αvß5 regulate angiogenesis and invasiveness in cancer, potentially by modulating activation of the transforming growth factor (TGF)-ß pathway. The randomized phase III CENTRIC and phase II CORE trials explored the integrin inhibitor cilengitide in patients with newly diagnosed glioblastoma with versus without O6-methylguanine DNA methyltransferase (MGMT) promoter methylation. These trials failed to meet their primary endpoints.Immunohistochemistry was used to assess the levels of the target integrins of cilengitide, αvß3 and αvß5 integrins, of αvß8 and of their putative target, phosphorylation of SMAD2, in tumor tissues from CENTRIC (n=274) and CORE (n=224).αvß3 and αvß5 expression correlated well in tumor and endothelial cells, but showed little association with αvß8 or pSMAD2 levels. In CENTRIC, there was no interaction between the biomarkers and treatment for prediction of outcome. In CORE, higher αvß3 levels in tumor cells were associated with improved progression-free survival by central review and with improved overall survival in patients treated with cilengitide.Integrins αvß3, αvß5 and αvß8 are differentially expressed in glioblastoma. Integrin levels do not correlate with the activation level of the canonical TGF-ß pathway. αvß3 integrin expression may predict benefit from integrin inhibition in patients with glioblastoma lacking MGMT promoter methylation.

Integrins αvß3 and αvß5 as prognostic, diagnostic, and therapeutic targets in gastric cancer.

BACKGROUND: We investigated the expression of two αv integrins, αvß3 and αvß5, in gastric cancer (GC) by testing the following hypotheses: that these molecules are expressed in GC; that they are implicated in GC biology; that they help to distinguish between the two major histological subtypes of GC, according to Laurén; and that they are prognostically relevant. METHODS: Formalin-fixed and paraffin-embedded tissue samples from 482 GC samples were stained immunohistochemically using rabbit monoclonal antibodies directed against αvß3 (EM22703) and αvß5 (EM09902). Immunostaining of tumor, stroma, and endothelial cells was evaluated separately by the quantity and intensity, generating an immunoreactivity score. The immunoreactivity score of both antibodies was correlated with clinicopathology data and patient survival. RESULTS: Each integrin was expressed in at least one tumor component in all GCs. Both were expressed significantly more often in the intestinal phenotype according to Laurén. Moreover, patients who grouped as "positive" for expression of αvß3 on endothelial cells, and patients with an intestinal type GC, grouped as "negative" for expression of αvß5 on stroma cells, had significantly longer survival. The expression of αvß5 on stroma cells was confirmed to be an independent prognostic factor of intestinal-type GC. CONCLUSION: The expression of αvß3 and αvß5 in at least one tumor component in all GC samples is an interesting new result that should form a basis for further investigations; for example, regarding selective integrin antagonists and the value of αvß3 and αvß5 as putative prognostic biomarkers. Moreover, both markers might be helpful in the routine classification of GC subtypes.

αvß3, αvß5 and αvß6 integrins in brain metastases of lung cancer.

Integrins are transmembranous adhesion molecules postulated to be involved in the brain metastatic cascade. We investigated the correlation of alpha v beta 3 (αvß3), alpha v beta 5 (αvß5) and alpha v beta 6 (αvß6) integrin isoform expression with clinical characteristics including survival times in lung cancer patients with brain metastases (BM). All BM from lung cancer operated at our institution between 1990 and 2011, were identified; where available, primary tumors were retrieved as well. Immunohistochemical analysis for αvß3, αvß5 and αvß6 integrin subunits was performed and correlated with Ki67 and hypoxia-inducible factor (HIF)-1α indexes. Clinical data including survival data were obtained by chart review. 191 BM specimens of 191 patients with histologically confirmed lung cancer (172 non-small cell lung cancer and 19 small cell lung cancer) were included. In 18 patients matched primary tumor samples were available. αvß6 expression was commonly found on BM tumor cells (103/191; 53.9 %) and showed a significant association with low Ki67 proliferation indices (46 vs. 36 %, p = 0.001, Mann-Whitney U test) and favorable survival times (p = 0.020; log rank test) in patients with non-squamous NSCLC BM. αvß5 expression was highly expressed on vascular structures (167/191; 87.4 %) and tumor stroma in BM (151/191; 79.1 %) and associated with high HIF-1α indices (60 vs. 90, p = 0.007, Mann-Whitney U test). αvß3 expression was more frequently found on vascular structures in BM than in primary tumors (68.1 vs. 5.6 %; p = 0.645; Chi square test) and its expression in BM tumor cells correlated with low Ki67 indices (41 vs. 28 %; p = 0.046, Mann-Whitney U test). Expression of αv integrin subunits seem to be of pathobiological and clinical relevance in patients with NSCLC BM. Further investigations of their involvement in the brain metastatic cascade and their role as biomarkers are warranted.

Atomic basis for the species-specific inhibition of αV integrins by monoclonal antibody 17E6 is revealed by the crystal structure of αVß3 ectodomain-17E6 Fab complex.

The function-blocking, non-RGD-containing, and primate-specific mouse monoclonal antibody 17E6 binds the αV subfamily of integrins. 17E6 is currently in phase II clinical trials for treating cancer. To elucidate the structural basis of recognition and the molecular mechanism of inhibition, we crystallized αVß3 ectodomain in complex with the Fab fragment of 17E6. Protein crystals grew in presence of the activating cation Mn(2+). The integrin in the complex and in solution assumed the genuflected conformation. 17E6 Fab bound exclusively to the Propeller domain of the αV subunit. At the core of αV-Fab interface were interactions involving Propeller residues Lys-203 and Gln-145, with the latter accounting for primate specificity. The Propeller residue Asp-150, which normally coordinates Arg of the ligand Arg-Gly-Asp motif, formed contacts with Arg-54 of the Fab that were expected to reduce soluble FN10 binding to cellular αVß3 complexed with 17E6. This was confirmed in direct binding studies, suggesting that 17E6 is an allosteric inhibitor of αV integrins.

Structural basis for pure antagonism of integrin αVß3 by a high-affinity form of fibronectin.

Integrins are important therapeutic targets. However, current RGD-based anti-integrin drugs are also partial agonists, inducing conformational changes that trigger potentially fatal immune reactions and paradoxical cell adhesion. Here we describe the first crystal structure of αVß3 bound to a physiologic ligand, the tenth type III RGD domain of wild-type fibronectin (wtFN10), or to a high-affinity mutant (hFN10) shown here to act as a pure antagonist. Comparison of these structures revealed a central π-π interaction between Trp1496 in the RGD-containing loop of hFN10 and Tyr122 of the ß3 subunit that blocked conformational changes triggered by wtFN10 and trapped hFN10-bound αVß3 in an inactive conformation. Removing the Trp1496 or Tyr122 side chains or reorienting Trp1496 away from Tyr122 converted hFN10 into a partial agonist. These findings offer new insights into the mechanism of integrin activation and a basis for the design of RGD-based pure antagonists.

Integrins and their ligands are expressed in non-small cell lung cancer but not correlated with parameters of disease progression.

The aim of this study was to investigate the expression of integrins, their ligands, and integrin signaling-related molecules in a cohort of human primary non-small cell lung cancers (NSCLC). Formalin-fixed and paraffin-embedded tissue samples from 215 NSCLC were immunohistochemically stained using antibodies directed against αvß3, αvß5, αvß6, αvß8, αv, osteopontin, fibronectin, vitronectin, epidermal growth factor (EGFR), vascular endothelial growth factor receptor (VEGFR), and Ki67. Immunostaining of tumor, stroma, and endothelial cells was evaluated separately by quantity and intensity (tumor cells) or intensity (stroma and endothelial cells) expressed in an immunoreactivity score. We studied correlations between the staining patterns of the different markers and of marker expression with clinicopathological data and patient survival. In the majority of NSCLC, each marker was expressed in at least one tumor component. As expected, αv and αv integrin heterodimers were significantly co-expressed, as were integrins and EGFR. Vitronectin was expressed significantly more often in smaller (T-category) and in well-differentiated tumors; Ki67 index was higher in larger (T-category) and in poorly differentiated tumors. No significant correlation was found between any marker expression and gender, venous invasion, lymph vessel invasion, lymph node metastasis, or survival. Although integrin expression does not seem to be associated with indicators of progression of NSCLC, the expression of αvß3 in 89 % and αvß5 in 100 % of NSCLC is novel and merits to be further investigated.

Comparing the expression of integrins αvß3, αvß5, αvß6, αvß8, fibronectin and fibrinogen in human brain metastases and their corresponding primary tumors.

AIMS: To evaluate the expression of αv-series integrins in brain metastases. Inhibitors targeting these integrins are being tested for their therapeutic potential. MATERIAL AND METHOD: The extracellular regions of the αvß3, αvß5, αvß6, αvß8, the cytoplasmic domain of ß3, the αv-chain, and the ECM molecules fibronectin and fibrinogen were studied immunohistochemically in a series of 122 carcinoma and 60 melanomas metastatic to the central nervous system. In addition, 38 matched primary and metastatic tumors to the brain were compared directly. RESULTS: The αv-subunit was generally moderately to highly expressed in most tumors. αvß3 and cytoplasmic ß3 were weakly to moderately detectable in metastatic renal cell carcinomas and melanomas, αvß5 was prominently expressed in metastatic renal and colorectal carcinomas, αvß6 was most abundantly detectable in metastatic lung adenocarcinomas, but absent in melanomas. The tumor associated vessels in CNS metastases consistently expressed αvß3, αvß5, αv-, fibronectin and fibrinogen, however, mostly at low levels, while αvß6, αvß8 were lacking in vasculature. The comparative analysis of 38 matched primary tumors and brain metastases showed comparable levels of expression only for αvß3 and αvß8, while αvß6 and αvß5 were higher in primaries. CONCLUSION: We confirmed that integrin expression exhibits considerable heterogeneity according to tumor origin. αvß5 is the most promising target for integrin targeted treatment in brain metastases.

Invasion patterns in brain metastases of solid cancers.

BACKGROUND: Brain metastases are generally considered to be well demarcated from the surrounding brain parenchyma, although infiltrative growth patterns have been observed. We systemically investigated infiltration patterns and expression of adhesion molecules in a large and well-defined series of autopsy cases of brain metastases. METHODS: Ninety-seven autopsy specimens from 57 brain metastasis patients (primary tumor: 27 lung cancer, 6 breast cancer, 8 melanoma, 2 colorectal cancer, 1 kidney cancer, and 13 other) were evaluated for patterns of invasion into surrounding brain parenchyma. Expression of integrins αv; cytoplasmic ß3, αvß3, αvß5, αvß6, and αvß8; and of E and N cadherin were evaluated using immunohistochemistry. RESULTS: Three main invasion patterns were seen: well-demarcated growth (29/57, 51%), vascular co-option (10/57, 18%), and diffuse infiltration (18/57, 32%). There was no statistically significant association of invasion pattern with primary tumor type, although vascular co-option was most common in melanoma brain metastases (4/10). Invasion patterns of different brain metastases of the same patient were highly concordant (P < .001, chi-square test). Distance of infiltration from the main tumor mass ranged from 12.5 µm to 450 µm (median 56.2 µm) and was not significantly different between the vascular co-option and the diffuse infiltration groups. Levels of αvß6 were significantly higher in the well-demarcated group than in the vascular co-option and the diffuse infiltration groups (P = .033, Kruskal-Wallis test). Expression of αvß5 in tumor cells was higher in brain metastasis lesions previously treated with stereotactic radiosurgery (P = .034, chi-square test). CONCLUSIONS: Distinct invasion patterns of brain metastases into the brain parenchyma are not specific for primary tumor types, seem to be influenced by expression of αv integrin complexes, and may help to guide clinical decision-making.

αv-Integrin isoform expression in primary human tumors and brain metastases.

UNLABELLED: To determine whether metastasis to brain is associated with altered expression patterns of integrins, we investigated the expression of αvß3, αvß5, αvß6 and αvß8 integrins in primary malignancies and metastases to brain of breast, lung and renal carcinomas and in malignant melanoma. Inhibitors of αv integrins are currently in clinical trials for glioblastoma. The role of integrins in the process of brain metastasis from other human tumors is unknown. Immunohistochemistry with novel integrin subtype specific rabbit monoclonal antibodies was performed on tissue microarrays of archival material of surgical biopsies taken from primary tumors and brain metastases. Integrin αvß3 expression was increased in brain metastases compared to primary tumors of breast adenocarcinoma, non-small cell lung cancer, renal clear cell cancer and malignant cutaneous melanoma (all p < 0.01). Similarly, integrin αvß8 expression was increased in brain metastases compared to primary tumors of breast cancer (p < 0.0001), lung cancer (p < 0.01) and renal cancer (p < 0.0001), with a similar trend in metastatic melanoma. Integrin αvß5 was expressed in most primary tumors (98% breast cancer; 67% lung cancer; 90% renal cancer; 89% melanoma) and showed a stronger expression in brain metastases compared to primary tumors from lung cancer and melanoma (p < 0.05). Also integrin αvß6 expression was increased in brain metastases compared to primary breast cancer (p < 0.001). CONCLUSIONS: The stronger αv-integrin expression in brain metastases, especially of αvß3 and αvß8 integrins, suggests that certain αv integrin are involved in the process of brain metastasis. αv Integrins may be therapeutic targets for patients with metastatic cancer in brain.

Validation and comparison of anti-αvß3 and anti-αvß5 rabbit monoclonal versus murine monoclonal antibodies in four different tumor entities.

Integrins are pivotal in cancer biology and are putative candidates for cancer therapy. The investigation of integrins has been hampered by the lack of antibodies suitable for formalin-fixed and paraffin-embedded (FFPE) tissue specimens. Here, we validated monoclonal rabbit antibodies (RabMAbs) against integrins αvß3 (EM22703) and αvß5 (EM09902) with murine monoclonal antibodies (MuMabs) LM609 (against αvß3) and P1F6 (against αvß5), in immunohistochemistry. Immunostaining was performed on sections of matching unfixed, cryoconserved (CC) and FFPE tissue from 19 colorectal, 20 lung, 17 breast, and 9 ovarian carcinomas. Sections were stained with LM609 and P1F6 and compared with the immunoreactions of the RabMAbs. The degree of concordance was assigned for staining patterns and intensity. Concordance between MuMAbs and RabMAbs ranged from weak, for anti-αvß5 antibodies, to nearly complete for anti-αvß3 antibodies. We confirmed that MuMAbs LM609 and P1F6 bound very weakly in FFPE tissue and no staining was seen. By contrast, RabMAbs EM22703 and EM09902 generally showed a high degree of agreement in staining patterns of CC and FFPE tissue. In summary, the RabMAbs had overlapping staining patterns that were generally more intense for CC when compared with FFPE material. This study suggests that EM22703 and EM09902 staining closely matches the staining of standard MuMAbs and also does so in archival FFPE tissue.

Longitudinal expression analysis of αv integrins in human gliomas reveals upregulation of integrin αvß3 as a negative prognostic factor.

Integrin inhibitors targeting αv series integrins are being tested for their therapeutic potential in patients with brain tumors, but pathologic studies have been limited by lack of antibodies suitable for immunohistochemistry (IHC) on formalin-fixed, paraffin-embedded specimens. We compared the expression of αv integrins by IHC in brain tumor and normal human brain samples with gene expression data in a public database using new rabbit monoclonal antibodies against αvß3, αvß5, αvß6, and αvß8 complexes using both manual and automated microscopy analyses. Glial tumors usually shared an αvß3-positive/αvß5-positive/αvß8-positive/αvß6-negative phenotype. In 94 WHO (World Health Organization) grade II astrocytomas, 85 anaplastic astrocytomas WHO grade III, and 324 glioblastomas from archival sources, expression of integrins generally increased with grade of malignancy. Integrins αvß3 and αvß5 were expressed in many glioma vessels; the intensity of vascular expression of αvß3 increased with grade of malignancy, whereas αvß8 was absent. Analysis of gene expression in an independent cohort showed a similar increase in integrin expression with tumor grade, particularly of ITGB3 and ITGB8; ITGB6 was not expressed, consistent with the IHC data. Parenchymal αvß3 expression and ITGB3 gene overexpression in glioblastomas were associated with a poor prognosis, as revealed by survival analysis (Kaplan-Meier logrank, p = 0.016). Together, these data strengthen the rationale for anti-integrin treatment of glial tumors.

Integrin control of the transforming growth factor-ß pathway in glioblastoma.

Transforming growth factor-ß is a central mediator of the malignant phenotype of glioblastoma, the most common and malignant form of intrinsic brain tumours. Transforming growth factor-ß promotes invasiveness and angiogenesis, maintains cancer cell stemness and induces profound immunosuppression in the host. Integrins regulate cellular adhesion and transmit signals important for cell survival, proliferation, differentiation and motility, and may be involved in the activation of transforming growth factor-ß. We report that αvß3, αvß5 and αvß8 integrins are broadly expressed not only in glioblastoma blood vessels but also in tumour cells. Exposure to αv, ß3 or ß5 neutralizing antibodies, RNA interference-mediated integrin gene silencing or pharmacological integrin inhibition using the cyclic RGD peptide EMD 121974 (cilengitide) results in reduced phosphorylation of Smad2 in most glioma cell lines, including glioma-initiating cell lines and reduced transforming growth factor-ß-mediated reporter gene activity, coinciding with reduced transforming growth factor-ß protein levels in the supernatant. Time course experiments indicated that the loss of transforming growth factor-ß bioactivity due to integrin inhibition likely results from two distinct mechanisms: an early effect on activation of preformed inactive protein, and second, major effect on transforming growth factor-ß gene transcription as confirmed by decreased activity of the transforming growth factor-ß gene promoter and decreased transforming growth factor-ß(1) and transforming growth factor-ß(2) messenger RNA expression levels. In vivo, EMD 121974 (cilengitide), which is currently in late clinical development as an antiangiogenic agent in newly diagnosed glioblastoma, was a weak antagonist of pSmad2 phosphorylation. These results validate integrin inhibition as a promising strategy not only to inhibit angiogenesis, but also to block transforming growth factor-ß-controlled features of malignancy including invasiveness, stemness and immunosuppression in human glioblastoma.

The αVß3/αVß5 integrin inhibitor cilengitide augments tumor response to melphalan isolated limb perfusion in a sarcoma model.

Isolated limb perfusion (ILP) with melphalan and tumor necrosis factor (TNF)-α is used to treat bulky, locally advanced melanoma and sarcoma. However, TNF toxicity suggests a need for better-tolerated drugs. Cilengitide (EMD 121974), a novel cyclic inhibitor of alpha-V integrins, has both anti-angiogenic and direct anti-tumor effects and is a possible alternative to TNF in ILP. In this study, rats bearing a hind limb soft tissue sarcoma underwent ILP using different combinations of melphalan, TNF and cilengitide in the perfusate. Further groups had intra-peritoneal (i.p.) injections of cilengitide or saline 2 hr before and 3 hr after ILP. A 77% response rate (RR) was seen in animals treated i.p. with cilengitide and perfused with melphalan plus cilengitide. The RR was 85% in animals treated i.p. with cilengitide and ILP using melphalan plus both TNF and cilengitide. Both RRs were significantly greater than those seen with melphalan or cilengitide alone. Histopathology showed that high RRs were accompanied by disruption of tumor vascular endothelium and tumor necrosis. Compared with ILP using melphalan alone, the addition of cilengitide resulted in a three to sevenfold increase in melphalan concentration in tumor but not in muscle in the perfused limb. Supportive in vitro studies indicate that cilengitide both inhibits tumor cell attachment and increases endothelial permeability. Since cilengitide has low toxicity, these data suggest the agent is a good alternative to TNF in the ILP setting.

Matched rabbit monoclonal antibodies against αv-series integrins reveal a novel αvß3-LIBS epitope, and permit routine staining of archival paraffin samples of human tumors.

The relationship between integrin expression and function in pathologies is often contentious as comparisons between human pathological expression and expression in cell lines is difficult. In addition, the expression of even integrins αvß6 and αvß8 in tumor cell lines is not comprehensively documented. Here, we describe rabbit monoclonal antibodies (RabMabs) against the extracellular domains of αv integrins that react with both native integrins and formalin fixed, paraffin embedded (FFPE) human tissues. These RabMabs, against αvß3 (EM22703), αvß5 (EM09902), αvß6 (EM05201), αvß8 (EM13309), and pan-αv (EM01309), recognize individual integrin chains in Western blots and in flow cytometry. EM22703 detected a ligand-induced binding site (LIBS), reporting an epitope enhanced by the binding of an RGD-peptide to αvß3. αvß8 was rarely expressed in human tumor specimens, and weakly expressed in non-small-cell lung carcinoma (NSCLC). However, ovarian carcinoma cell lines expressed αvß8, as did some melanoma cells, whereas U87MG glioma lacked αvß8 expression. We observed an unexpected strong expression of αvß6 in tumor samples of invasive ductal breast adenoma, colorectal carcinoma (CRC), and NSCLC. αvß3 was strongly expressed in some invasive NSCLC cohorts. Interestingly, PC3 prostate cell and human prostate tumors did not express αvß3. The RabMabs stained plasma membranes in FFPE-immunohistochemistry (IHC) samples of tumor cell lines from lung, ovary, colon, prostate, squamous cell carcinoma of head and neck (SCCHN), breast, and pancreas carcinomas. The RabMabs are unique tools for probing αv integrin biology, and suggest that especially αvß6 and αvß8 biologies still have much to reveal.

Integrins as therapeutic targets.

Integrins are a large family of molecules that are central regulators in multicellular biology. They orchestrate cell-cell and cell-extracellular matrix (ECM) adhesive interactions from embryonic development to mature tissue function. Diverse human pathologies involve integrin adhesion, including thrombotic diseases, inflammation, cancer, fibrosis and infectious diseases. Integrins are exciting pharmacological targets because they are exposed on the cell surface and are sensitive to pharmacological blockade, but the scale of current efforts involving integrin therapeutics continues to surprise. Several therapeutics targeting integrins are effective drugs: five have been approved for use in clinic, with combined sales of over $1.5 billion in 2010 (based on company reports from that year). We gathered information from three major drug-trial databases and found that ∼260 anti-integrin drugs have entered clinical trials. Here we overview integrins as drug targets and focus on cancer.