Minimal Residual Disease Assessment in Lymphoid Malignancies - Episode 9
Michael L. Wang, MD: In general, flow cytometry can detect 1 malignant tumor cell out of 10,000 normal cells, and the PCR [polymerase chain reaction] can detect 1 malignant cell out of 100,000 normal cells. The most current technology, clonoSEQ, claims they can detect 1 out of 1 million. So, you can remember that flow cytometry is 10-4, PCR is 10-5, and the most recent updated technology of circulating DNA aims for 10-6.
The reliability is used as the sensitivity and the specificity. So, with sensitivity, it is very important that the tests are sensitive because if there’s a low level, you are still able to detect it. The specificity means what you’re detecting is the real problem, and not the background noise. So, both specificity and sensitivity of MRD testing is very important. Every test has to improve on their sensitivity and specificity. You can see that in terms of sensitivity, flow cytometry is less sensitive than PCR, and PCR is less sensitive than the most updated technology, such as clonoSEQ. But the technology also improves on the specificity. ClonoSEQ is very specific, and the circulating DNAs are also very specific. So, we’re improving our MRD testing both by sensitivity and by specificity.
The current technology, clonoSEQ, meets the threshold of 1 out of 1 million. It needs further validation, but it’s already being used in many places. The other technologies, the circulating DNA, are way behind, but technologies are being invented. They’re just not validated yet. They’re in the process of being validated.
Transcript Edited for Clarity