With the increased uses of targeted therapeutics,diagnostic detection of target mutations becomes essential for the effective clinical applications of targeted therapeutics.
Currently, there are two types of methods detecting target mutations in clinics: one is based on DNA sequence and the other uses the newly developed mutation-specific antibodies
recognizing mutated proteins. Each method has its own advantages and disadvantages. Here, we explored the sensitivity and specificity of a new commercially available BRAF(V600E) mutation-specific mouse monoclonal antibody. Using routine manual immunohistochemistry (IHC), we tested tumor tissues from 38 melanoma patients.
For those melanoma tissues with abundant en dogenous melanin, we pretreated the tumor tissues with3 % hydrogen peroxide to remove melanin for reliable signal detection. We also performed DNA sequencing and ARMS-PCR analyses for these 38 tumor samples.
Comparing to the results from DNA-based detection methods, the IHC method with this BRAF(V600E) mutation-specific antibody displayed 100 % sensitivity and 92.9 % specificity. Hence, this IHC detection is sensitive for clinic uses as a simple, fast, inexpensive, and reliable method to screen cancer patients for the BRAF(V600E) mutation and could be easily adapted for use in most hospital pathology laboratories.
The IHC method avoids the above discussed drawbacks associated with the pyrosequencing and ARMS-PCR methods. However, this simple and relatively new method(based on the newly developed anti-B-Raf(V600E) antibody)
needs to compare with the data from the DNA sequencing methods, at least in the early stage of developing this IHC method. Other than the anti-B-Raf(V600E) mouse monoclonal antibody used here (from NewEast Biosciences, Malvern,PA, USA), there is another antihuman BRAF V600E antibody(Clone VE1 from Spring Bioscience, Pleasanton, CA, USA). The VE1 antibody (diluted at 1:100) had to be used with the automatic IHC instrument. In our hands, the VE1 antibodydid not work with manual IHC and could not detect the BRAF(V600E) mutation under the conditions that we used. In contrast, the anti-B-Raf(V600E) antibody that we used here could detect BRAF(V600E) with either manual or automatic IHC.
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