On 2016 Oct 31, Daniela Drandi commented:

Dr. Kumar S. and Colleagues gave a comprehensive description of the role of the ancestors (MFC and ASOqPCR) and the new high-throughput (NGF and NGS) MRD techniques in MM. However, in the “molecular methods for MRD detection” section, the Authors briefly refer to our original work, (Drandi D et al. J Mol Diagn. 2015;17(6):652-60), in a way that misinterprets our findings. Infact, in their review the Authors concluded that ddPCR is a “less applicable and more labor intensive” method compared to qPCR. This statement is in contrast to what was observed in our original work, where the comparison between qPCR and ddPCR showed that: 1) ddPCR has sensitivity, accuracy, and reproducibility comparable to qPCR; 2) ddPCR allows to bypass the standard curve issue, ensuring the quantification of samples with low tumor invasion at baseline or lacking MFC data; 3) ddPCR has a substantial benefit in terms of reduced costs, labor intensiveness and waste of precious tissue (see Drandi D et al., supplemental table S3). Notably, according to these findings, a standardization process is currently ongoing, both in the European (ESLHO-EuroMRD group) and in the Italian (Italian Lymphoma Foundation (FIL)-MRD Network) context. We agree that ddPCR does not overcome all the limitation of qPCR including the need, in IGH-based MRD, of patients-specific ASO-primers. However, as we showed, ddPCR is a feasible and an attractive alternative method for MRD detection, especially in term of applicability and labor intensiveness.

On 2016 Oct 31, Daniela Drandi commented:

Dr. Kumar S. and Colleagues gave a comprehensive description of the role of the ancestors (MFC and ASOqPCR) and the new high-throughput (NGF and NGS) MRD techniques in MM. However, in the “molecular methods for MRD detection” section, the Authors briefly refer to our original work, (Drandi D et al. J Mol Diagn. 2015;17(6):652-60), in a way that misinterprets our findings. Infact, in their review the Authors concluded that ddPCR is a “less applicable and more labor intensive” method compared to qPCR. This statement is in contrast to what was observed in our original work, where the comparison between qPCR and ddPCR showed that: 1) ddPCR has sensitivity, accuracy, and reproducibility comparable to qPCR; 2) ddPCR allows to bypass the standard curve issue, ensuring the quantification of samples with low tumor invasion at baseline or lacking MFC data; 3) ddPCR has a substantial benefit in terms of reduced costs, labor intensiveness and waste of precious tissue (see Drandi D et al., supplemental table S3). Notably, according to these findings, a standardization process is currently ongoing, both in the European (ESLHO-EuroMRD group) and in the Italian (Italian Lymphoma Foundation (FIL)-MRD Network) context. We agree that ddPCR does not overcome all the limitation of qPCR including the need, in IGH-based MRD, of patients-specific ASO-primers. However, as we showed, ddPCR is a feasible and an attractive alternative method for MRD detection, especially in term of applicability and labor intensiveness.