MYD88<sup>L265P</sup> Detection in IgM Monoclonal Gammopathies: Methodological Considerations for Routine Implementation
Martina Ferrante,
Daniela Furlan,
Silvia Zibellini,
Michela Borriero,
Chiara Candido,
Nora Sahnane,
Silvia Uccella,
Elisa Genuardi,
Beatrice Alessandria,
Benedetta Bianchi,
Barbara Mora,
Daniele Grimaldi,
Irene Defrancesco,
Cristina Jiménez,
Federica Cavallo,
Dario Ferrero,
Irene Dogliotti,
Michele Merli,
Marzia Varettoni,
Simone Ferrero,
Daniela Drandi
Affiliations
Martina Ferrante
Department of Molecular Biotechnology and Health Sciences, Hematology Division, University of Torino, 10100 Torino, Italy
Daniela Furlan
Department of Medicine and Surgery, University of Insubria, 21100 Varese, Italy
Silvia Zibellini
Division of Hematology, IRCCS Foundation, Policlinico San Matteo, 27100 Pavia, Italy
Michela Borriero
Department of Molecular Biotechnology and Health Sciences, Hematology Division, University of Torino, 10100 Torino, Italy
Chiara Candido
Division of Hematology, IRCCS Foundation, Policlinico San Matteo, 27100 Pavia, Italy
Nora Sahnane
University Hospital “Ospedale di Circolo e Fondazione Macchi”-ASST Sette Laghi, University of Insubria, 21100 Varese, Italy
Silvia Uccella
Department of Medicine and Surgery, University of Insubria, 21100 Varese, Italy
Elisa Genuardi
Department of Molecular Biotechnology and Health Sciences, Hematology Division, University of Torino, 10100 Torino, Italy
Beatrice Alessandria
Department of Molecular Biotechnology and Health Sciences, Hematology Division, University of Torino, 10100 Torino, Italy
Benedetta Bianchi
University Hospital “Ospedale di Circolo e Fondazione Macchi”-ASST Sette Laghi, University of Insubria, 21100 Varese, Italy
Barbara Mora
University Hospital “Ospedale di Circolo e Fondazione Macchi”-ASST Sette Laghi, University of Insubria, 21100 Varese, Italy
Daniele Grimaldi
Department of Molecular Biotechnology and Health Sciences, Hematology Division, University of Torino, 10100 Torino, Italy
Irene Defrancesco
Division of Hematology, IRCCS Foundation, Policlinico San Matteo, 27100 Pavia, Italy
Cristina Jiménez
Hematology Department, University Hospital of Salamanca, Research Biomedical Institute of Salamanca (IBSAL), CIBERONC and Center for Cancer Research-IBMCC (USAL-CSIC), 37001 Salamanca, Spain
Federica Cavallo
Department of Molecular Biotechnology and Health Sciences, Hematology Division, University of Torino, 10100 Torino, Italy
Dario Ferrero
Department of Molecular Biotechnology and Health Sciences, Hematology Division, University of Torino, 10100 Torino, Italy
Irene Dogliotti
Stem Cell Transplant Unit, University Hospital AOU Città della Salute e della Scienza, 10100 Torino, Italy
Michele Merli
University Hospital “Ospedale di Circolo e Fondazione Macchi”-ASST Sette Laghi, University of Insubria, 21100 Varese, Italy
Marzia Varettoni
Division of Hematology, IRCCS Foundation, Policlinico San Matteo, 27100 Pavia, Italy
Simone Ferrero
Department of Molecular Biotechnology and Health Sciences, Hematology Division, University of Torino, 10100 Torino, Italy
Daniela Drandi
Department of Molecular Biotechnology and Health Sciences, Hematology Division, University of Torino, 10100 Torino, Italy
In IgM monoclonal gammopathies MYD88L265P is a prognostic and predictive biomarker of therapy response. MYD88L265P detection is mainly performed by allele-specific quantitative PCR (ASqPCR), however recently, droplet digital PCR (ddPCR) has been proved to be suitable for MYD88L265P screening and minimal residual disease monitoring (MRD). This study compared ASqPCR and ddPCR to define the most sensitive method for MYD88L265P detection in bone marrow (BM), peripheral blood (PB) sorted or unsorted CD19+ cells, and in plasma cell-free DNA (cfDNA). Overall, the analysis showed a good concordance rate (74%) between the two methods, especially in BM samples, while discordances (26%) were mostly in favor of ddPCR (ddPCR+ vs. ASqPCR-) and were particularly evident in samples with low mutational burden, such as PB and cfDNA. This study highlights ddPCR as a feasible approach for MYD88L265P detection across different specimen types (including cfDNA). Interestingly, its high sensitivity makes CD19+ selection dispensable. On the other hand, our results showed that MYD88L265P detection on PB samples, especially with ASqPCR, is suboptimal for screening and MRD analysis. Finally, significantly different MYD88L265P mutational levels observed between Waldenström Macroglobulinemia and IgM monoclonal gammopathy of undetermined significance patients suggest the need for further studies in order to identify possible correlations between mutational levels and risk of progression to Waldenström.
