Analysis of RNA Carried by Tumor-educated Platelets Yields Valuable Diagnostic Clues

Analysis of tumor RNA carried in the afflicted individual's blood platelets may be more useful than other "liquid biopsy" technologies for diagnosing cancer and determining its primary location and potential therapeutic approaches.

Tumor-educated blood platelets (TEPs), which have incorporated molecules shed by tumors, have been implicated as central players in the systemic and local responses to tumor growth, thereby altering their RNA profile.

Investigators at Massachusetts General Hospital (Boston, USA) evaluated the diagnostic potential of TEPs by mRNA sequencing of 283 platelet samples. They reported in the October 29, 2015, online edition of the journal Cancer Cell that after amplifying and sequencing the amount of platelet RNA found in the equivalent of a single drop of blood from each individual, they had identified more than 5,000 different platelet RNAs.

Comparing RNA profiles of healthy donors with those of 228 cancer patients revealed increased levels of nearly 1,500 different RNA molecules and decreased levels of almost 800. Analysis of the levels of around 1,000 RNAs from about 300 individuals with a dedicated algorithm that classified whether not they indicated the presence of cancer did so with 96% percent accuracy. All of the patients with localized tumors and 33 of the 39 with tumors of the central nervous system were accurately diagnosed. Across six different tumor types, the location of the primary tumor was correctly identified with 71% accuracy.

"By combining next-generation-sequencing gene expression profiles of platelet RNA with computational algorithms we developed, we were able to detect the presence of cancer with 96% accuracy," said contributing author Dr. Bakhos Tannous, associate professor of neurology at Massachusetts General Hospital. "Platelet RNA signatures also provide valuable information on the type of tumor present in the body and can guide selection of the most optimal treatment for individual patients.

"We observed that the mRNA profiles of tumor-educated platelets have the sensitivity and specificity to detect cancer, even in early, non-metastasized tumors," said Dr. Tannous. "We are further assessing the potential of TEP-based screening for therapeutic decision making and also investigating how noncancerous diseases may further influence the RNA repertoire of TEPs."

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