P-036: Implementation of IgH/k Next Generation Sequencing for Multiple Myeloma Minimal Residual Disease monitoring: advantages in patients’ management during daily clinical practice.

Abstract

<h3>Background</h3> The introduction of novel agents into the therapeutic algorithm of Multiple Myeloma (MM) has led to remarkable improvements in the rate of Minimal Residual Disease (MRD) negative status. Sustained MRD negativity is a robust prognosticator and a driver of treatment strategies. Therefore, it is expected that MRD molecular tracking would become critical in the management of MM, and could be included in daily clinical practice. <h3>Aim</h3> To evaluate the performances of next generation sequencing (NGS), implemented as best practice in MM MRD daily evaluation. <h3>Methods</h3> A cohort of 166 newly diagnosed transplant-eligible and -ineligible MM pts were screened to define the ID clonotypes. MRD was firstly assessed at achievement of at least a very good partial response during maintenance, and thereafter once a year. In high-risk pts, MRD was also detected between 1° and 2° autologous stem-cell transplantation (ASCT). The ID clonotypes screening has been performed by NGS, using an assay covering IgH and Igk genes (Invivoscribe®). The MRD tracking has been done both by conventional ASO-qPCR and by NGS. Data were analyzed by Lymphotrack Dx and MRD software (Invivoscribe®). <h3>Results</h3> The ID clonotypes screening was successful in 158/166 pts (95%), even though a small proportion of pts resulted polyclonal (14/158). Overall, 63, 27 and 54 pts had IgH, Igk and IgH/k ID clonotypes, respectively, mainly restricted to the VH3 (47%) family genes. MRD assessment was performed by NGS in 124/144 pts (overall, 96 MRD samples for 64 pts monitored to date), with 10-5 sensitivity in most cases (75/96). 44 pts were assessed during maintenance and 23 achieved MRD-negativity. On the contrary, 20 pts were evaluated between 1° and 2° ASCT, resulting MRD-positive in all cases. Overall, few FU samples (13/96) were reported as "positive-not-quantifiable" (PNQ), since had residual disease levels of 10-7, much lower than the internal control. In a subset of 20 pts with trackable IgH/Igk sequences, pts-specific assays were designed, according to the EuroMRD guidelines. In these pts, MRD was tested both by ASO-qPCR (including a standard curve and healthy donor cells, to define the sensitivity and the specificity, respectively) and by NGS. Overall, ASO-qPCR allowed the tracking of a single MRD clone (with up to 10-4 sensitivity) in 12/20 pts (60%), whereas NGS was feasible in all of them, confirming the ASO-qPCR results, yet with higher sensitivity and >95% confidence. Moreover, in 2 cases, NGS allowed to disclose ASO-qPCR PNQ results due to nonspecific amplification, thus unveiling MRD negativity with 10-5 sensitivity. <h3>Conclusion</h3> NGS has been successfully implemented as best practice in the management of MM pts, showing the superiority of this method over ASO-qPCR conventional approach. The ID clonotype was defined in almost all pts included in the workflow, thus allowing their MRD molecular monitoring, according to the clinical requirements. <h3>Acknowledgment</h3> AIRC IG2018-22059