A Comparison of Estrogen Receptor SP1 and 1D5 Monoclonal Antibodies in Routine Clinical Use Reveals Similar Staining Results
ABSTRACT Clinical therapies for breast cancer are guided by estrogen receptor (ER) status determined by immunohistochemical analysis. A previous retrospective study comparing the recently generated rabbit SP1 monoclonal antibody (MAb) with the conventionally used mouse 1D5 MAb reported that 8% of breast carcinomas were SP1+/1D5- (correlating with good outcomes), and 2% were SP1-/1D5+ (correlating with poorer outcomes). This study on mostly previously frozen tissue implied that 1D5 fails to identify some women who may benefit from endocrine therapy. The current prospective study compared SP1 and 1D5 immunostaining on routinely processed consecutive cases of breast carcinoma. ER was classified using the same positive threshold used in the prior study (<1% negative; > or = 1% positive). Of 508 carcinomas, 2 were SP1+/1D5-, and none were SP1-/1D5+. Although SP1 is our preferred antibody, with more intense nuclear staining, both MAbs give similar results in tissue from routine clinical samples with discrepant results in fewer than 0.5% of cases.
Article: Antibody validation[Show abstract] [Hide abstract]
ABSTRACT: Antibodies are among the most frequently used tools in basic science research and in clinical assays, but there are no universally accepted guidelines or standardized methods for determining the validity of these reagents. Furthermore, for commercially available antibodies, it is clear that what is on the label does not necessarily correspond to what is in the tube. To validate an antibody, it must be shown to be specific, selective, and reproducible in the context for which it is to be used. In this review, we highlight the common pitfalls when working with antibodies, common practices for validating antibodies, and levels of commercial antibody validation for seven vendors. Finally, we share our algorithm for antibody validation for immunohistochemistry and quantitative immunofluorescence.BioTechniques 03/2010; 48(3):197-209. DOI:10.2144/000113382 · 2.95 Impact Factor
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ABSTRACT: We previously reported that delayed formalin fixation (DFF) has a negative effect on immunohistochemical staining of estrogen receptor (ER), progesterone receptor (PR), and HER2. The primary aim of the study was to determine if DFF affected commonly used clones of the ER and PR differentially. The specific clones evaluated were ER clones 1D5, 6F11, and SP1 and PR clones 16, 1E2, and PgR636. Ten breast cancer cases were dissected and fixed at different times (0, 10, and 30 minutes; 1, 2, 4, and 8 hours; and overnight) and were then stained with anti-ER and anti-PR antibodies. The mean Q score for ER started to decline at 2 to 4 hours for clones 1D5 and 6F11 and at 1 hour for SP1. SP1 was superior to 1D5 at the 8-hour mark (P = .03). The Q score for PR started to decline at 1 hour for clones PgR636 and 16 and 4 to 8 hours for 1E2 (P = .03). Based on our findings, it appears that regardless of the antibody clones evaluated, DFF has a negative effect on hormone receptors.American Journal of Clinical Pathology 11/2010; 134(5):813-9. DOI:10.1309/AJCPVCX83JWMSBNO · 2.51 Impact Factor
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ABSTRACT: Therapeutic decision-making for women diagnosed with breast cancer requires accurate determination of the estrogen receptor (ER) and progesterone receptor (PR). Decisions about adjuvant therapy are often based on the immunohistochemical (IHC) profile of the core needle biopsy sample (CNB) because the staining is not repeated on the final excisional biopsy (EB). The purpose of this study was to assess the concordance of breast cancer IHC receptor assays on CNB and EB. We identified 176 patients with matching breast CNB and EB that had available ER and PR. While the CNBs were processed and stained in different laboratories, the EB were processed and stained in our institution. The following antibodies were used 1D5, 6F11 and SP1 for ER, and PgR636, 16 and 1E2 for PR, from Dako, Leica and Ventana respectively. Correlation of scores of CNBs with matching EB was analyzed using Spearman correlation coefficients. Sensitivity, specificity, overall agreement and the kappa statistic were used to measure the concordance between CNB and EB. For CNB, there were 141 (80.1%) cases positive for ER and 118 (67%) cases positive for PR. For EB, there were 143 (81.3%) cases positive for ER and 130 (73.9%) cases positive for PR. Overall agreement for ER and PR was seen in 93% (95% CI = 0.88, 0.96) and 90% (95% CI = 0.84, 0.94) respectively. Overall, ER- CNB/ER+ EB was seen in seven (4%) cases and PR- CNB/PR+ EB in 15 (8.5%) cases. ER+ CNB/ER- EB was seen in five (2.8%) cases and PR+ CNB/PR- EB in three (1.7%) cases. To avoid erroneous omission of life-saving endocrine therapy ER and PR should be repeated on the EB for patients whose CNB has negative hormonal receptors.The Breast Journal 02/2011; 17(2):180-6. DOI:10.1111/j.1524-4741.2010.01051.x · 1.41 Impact Factor