Session: 651. Myeloma: Biology and Pathophysiology, excluding Therapy: Poster III
Hematology Disease Topics & Pathways:
Technology and Procedures, flow cytometry, NGS
Aims: To compare the prognostic value of MRD detection in autografts and bone marrow (BM) cells using 8-color MFC (EuroFlow-NGF) and NGS (Adaptive Biotechnologies), and also MRD levels between fresh and cryopreserved autografts using NGF.
Methods: The study enrolled 52 newly-diagnosed MM patients who underwent ASCT. The median age ASCT was 61 (range 41–69) years and included 29 males and 23 females at ISS I (n = 17), II (n = 23), and III (n = 12). Of these, 18 patients harbored high-risk chromosomal abnormalities including t(4;14) (n = 15), del17p and t(4;14) (n = 2), and complex (n = 1). Bortezomib-based chemotherapy was used for induction together with melphalan at 140 mg/m2 (n = 1) and 200 mg/m2 (n = 51) for conditioning before ASCT. 39 of 52 (75%) patients received maintenance therapy until progressive disease. The best responses achieved post-ASCT included 30 sCR, 4 CR, 15 VGPR, and 3 PR. Forty autografts, one from each MM patient, were analyzed using NGF and NGS protocols, and BM cells at pre/post-ASCT and autografts derived from 16 patients were analyzed using NGS. The EuroFlow-NGF method uses standard sample preparation; large numbers of cells are evaluated using an optimized 8-color antibody panel that facilitates accurate identification of discrimination between phenotypically aberrant plasma cells (aPCs) and their normal counterparts (Flores-Montero et al., Leukemia 2017). NGS-based MRD assessment was performed using Adaptive’s standardized NGS-MRD Assay (Seattle, WA) (Martinez-Lopez et al., Blood 2014). Eight additional autografts were used to assess MRD in both fresh and cryopreserved samples by NGF.
Results: MRD was evaluated in 48 of 52 autografts (92%) using NGF and in 44 of 52 autografts (85%) using NGS. We identified aPCs in autografts based on multivariate analysis of individual cell populations (e.g., CD56+, CD19−, CyIgκ+, and CD117+). As the results of NGF revealed a strong correlation with respect to MRD in fresh vs. thawed autografts (r = 0.999, P < 0.0001), MRD was subsequently evaluated in thawed autografts. The sensitivity of NGF was 1 × 10−5–2 × 10−6; the sensitivity of NGS was 1 × 10−6. 28 of 48 (58%) of the autografts were MRD-positive by NGF; 30 of 44 (68%) of the autografts were MRD-positive by NGS. MRD levels in autografts using NGF and NGS correlated with one another (r = 0.69, P < 0.0001; Fig. 1A). MRD negative in autografts by NGF cases (MRDNGF (-)) and MRDNGS (-) tended to show better progression-free survival (PFS) than MRDNGF (+) (P = 0.195) and MRDNGS (+) (P = 0.156), respectively. Furthermore, MRDNGS (-) showed significantly better overall survival (OS) than MRDNGS (+) (P = 0.03) (Fig. 1C) while MRDNGF (-) showed better OS than MRDNGF (+) (P = 0.09) (Fig. 1B). Our data revealed only a minimal correlation between MRD in the autografts (median 1.1 × 10−5, range 0–7.29 × 10−4) and in the BM cells at pre-ASCT (median 5.05 × 10−3, range 6 × 10−6–2.64 × 10−1; r = 0.09, P = 0.7) or at post-ASCT (median 2.11 × 10−4, range 0–9.09 × 10−3; r = 0.14, P = 0.6); MRD detected in the autografts was > 27 times lower than that detected in pre-ASCT BM cells, and MRD detected in the post-ASCT BM cells was > 3 times lower than that detected in pre-ASCT BM cells except for one case in which the ratio was increased by two times. Interestingly, while MRD was detected in all BM cells at pre-ASCT (n = 16), 4 of 16 (25%) of these autografts were MRDNGS-negative. The median of MRD levels of the 4 cases in pre-ASCT and post-ASCT BM cells were 4.14 × 10−4 (range 6-583 × 10−6) and 1.8 × 10−5 (range 0-27 × 10−6), respectively.
Conclusion: Although EuroFlow-NGF is a rapid and accurate method for detecting MRD, NGS was more sensitive and provided greater prognostic value than EuroFlow-NGF.
Disclosures: Takamatsu: Adaptive Biotechnologies: Honoraria; Bristol-Myers Squibb: Honoraria, Research Funding; Janssen Pharmaceutical: Consultancy, Honoraria, Research Funding; Ono pharmaceutical: Honoraria, Research Funding; SRL: Consultancy, Research Funding. Takezako: Bristol-Myers Squibb: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Janssen: Research Funding; Abbvie: Research Funding. Nakao: Symbio: Consultancy; Kyowa Kirin: Honoraria; Alexion: Research Funding; Novartis: Honoraria.
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