Aqueous Humor Can Serve as Surrogate Tumor Biopsy
FRIDAY, Oct. 13, 2017 -- A novel method will allow for analyses of tumor-derived DNA in eyes with retinoblastoma (Rb) undergoing salvage therapy that have not been enucleated, according to a study published online Oct. 12 in JAMA Ophthalmology.
Jesse L. Berry, M.D., from Children's Hospital Los Angeles, and colleagues isolated cell-free DNA (cfDNA) from six aqueous humor (AH) samples from three children with Rb, including two after primary enucleation and one undergoing multiple intravitreous injections of melphalan for vitreous seeding. Their objective was to determine whether the AH of Rb eyes has enough tumor-derived DNA to perform genetic analyses of the tumor, and they analyzed the AH for DNA, RNA, and micro-RNA using Qubit high-sensitivity kits.
The researchers found that in the enucleated samples, there was a corroborative pattern between the chromosomal copy number variation profiles of the AH cfDNA and tumor-derived DNA. From one child, a nonsense RB1 mutation (Lys→STOP) was identified from the AH samples obtained during melphalan injection. This same mutation was seen with Sanger sequencing of the AH cfDNA and tumor DNA with polymerase chain reaction primers targeting RB1 gene c.1075A.
"In this study evaluating nucleic acids in the AH from Rb eyes undergoing salvage therapy with intravitreous injection of melphalan, the results suggest that the AH can serve as a surrogate tumor biopsy when Rb tumor tissue is not available. This novel method will allow for analyses of tumor-derived DNA in Rb eyes undergoing salvage therapy that have not been enucleated," conclude the authors.
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Posted: October 2017