Adverse impact of high donor CD3+ cell dose on outcome following tandem auto-NMA allogeneic transplantation for high-risk myeloma.

High-risk (HR) multiple myeloma (MM) has poor outcomes with conventional therapy. Tandem autologous-non-myeloablative (NMA) allogeneic stem cell transplantation (autologous stem cell transplantation (ASCT)-NMA allogeneic SCT) is potentially curative secondary to graft-versus-myeloma effect. We retrospectively analysed ASCT-NMA allogeneic SCT outcomes of 59 HR and relapsed MM patients. At a median follow-up of 35.8 months, the outcomes for HR-MM upfront tandem ASCT-NMA allogeneic SCT and standard-risk (SR) MM upfront ASCT alone were comparable (median PFS 1166 days versus 1465 days, P=0.36; median overall survival (OS) not reached in both cohorts, P=0.31). The 5-year PFS and OS of patients who had ASCT-NMA allogeneic SCT after relapsing from previous ASCT were 30% and 48% respectively. High CD3+ cell dose (>3 × 108/kg) infusion was associated with more acute GvHD (grade 2-4) (47% vs 17.5%; P=0.03), extensive chronic GvHD (80% vs 50%; P=0.04), increased transplant-related mortality (26.3% vs 5%; P=0.009) and inferior OS (median OS 752 days vs not reached; P=0.002). On multivariate analysis, response achieved with tandem transplant (

Circulating tumour DNA analysis demonstrates spatial mutational heterogeneity that coincides with disease relapse in myeloma.

Mutational characterisation in multiple myeloma (MM) currently relies on bone marrow (BM) biopsy, which fails to capture the putative spatial and genetic heterogeneity of this multifocal disease. Analysis of plasma (PL)-derived circulating free tumour DNA (ctDNA) as an adjunct to BM biopsy, for mutational characterisation and tracking disease progression, was evaluated. Paired BM MM cell DNA and ctDNA from 33 relapsed/refractory (RR) and 15 newly diagnosed (ND) patients were analysed for KRAS, NRAS, BRAF and TP53 mutations using the OnTarget Mutation Detection (OMD) platform. OMD detected 128 mutations (PL=31, BM=59, both=38) indicating the presence of PL mutations (54%). A higher frequency of PL-only mutations was detected in RR patients than ND (27.2% vs 6.6%, respectively), authenticating the existence of spatial and genetic heterogeneity in advanced disease. Activating RAS mutations were more highly prevalent than previously described with 69% harboring at least one RAS mutation. Sequential ctDNA quantitation with droplet digital PCR through longitudinal PL tracking of specific clones in seven patients demonstrated changes in fractional abundance of certain clones reflective of the disease status. We conclude that ctDNA analysis as an adjunct to BM biopsy represents a noninvasive and holistic strategy for improved mutational characterisation and therapeutic monitoring of MM.