Stefania Oliva

Background: The level of measurable residual disease (MRD) is one of the most important features correlating depths of response and long‐term outcomes in multiple myeloma (MM) and MRD evaluation is currently the gold standard tool for assessing treatment response. Nevertheless, reproducibility across laboratories is a major concern, as discrepancies among results make comparability impractical. Aims: herein, we report preliminary results from the “Italian MM‐MRD network” project. Patients & Methods: MRD in bone marrow (BM) samples have been measured from newly diagnosed MM patients using next‐generation flow‐cytometry (NGF) or next‐generation sequencing (NGS) approaches in different laboratories. Results: The NGF workgroup (7 laboratories) implemented the Euro‐Flow Standard‐Operating‐Protocol to reach minimum 1 × 10 ⁻⁵ sensitivity. The inter‐operator retrospective study (Stage 1) showed high inter‐center concordance in monoclonal plasma cells detection (ICC = 0.90, p < 0.001), whereas moderate concordance was observed in the inter‐laboratory correlation (Stage 2) in in‐vivo samples (ICC = 0.63, p < 0.001), reaching a median limit‐of‐detection (LOD) and limit‐of‐quantification (LOQ) of 8 × 10−6 and 2 × 10 ⁻⁵ , respectively. Greater variability was also observed in the analysis of other BM cell populations. The NGS workgroup (4 laboratories) employed a targeted amplicon‐based approach to detect clonotypic IGH/IGK gene rearrangements in diagnostic samples, subsequently used to track MRD in mock samples. The experimental design was divided into three quality‐control (QC) rounds, focused on finding a shared strategy for clonotype identification (QC1: 100% concordance among centers), or quantifying MRD in mock samples (concordance: 81% [QC2]; 91% [QC3]). The 10 ⁻⁵ ‐sensitivity level was successfully reached in most of tested dilutions (QC2: 19/20 = 95%; QC3: 19/23 = 83%). Conclusion: Overall, this pilot study provided preliminary data for MRD harmonization across Italian centers, paving the way for an expanded network, aiming at reducing variability, improving comparability, and enabling broader use of MRD‐monitoring in clinical practice.

Background and Clinical Significance: Histiocytic sarcoma (HS) is a rare and aggressive form of malignant histiocytosis, often associated with poor prognosis. The diagnosis and management of HS are challenging due to the complexity of its pathogenesis, molecular profile, and the unclear cellular origin of histiocytic neoplasms, compounded by the limited literature on treatment strategies. Case Presentation: We report the case of a young patient with HS localized to the lymph nodes, spleen, and liver, who also presented with hemophagocytic lymphohistiocytosis (HLH) documented on bone marrow biopsy. Initial treatment with CHOEP-21 and ICE-21 chemotherapy resulted in only a partial metabolic response, as evidenced by a Fluorodeoxyglucose-Positron Emission Tomography (FDG-PET)/CT scan. Given the aggressive nature of the disease and the presence of HLH, an allogeneic hematopoietic stem cell transplantation (HSCT) from a matched unrelated donor was performed as consolidation therapy, leading to a progressive complete response without significant toxicity. A suspected relapse at 18 months post-transplant was excluded following a mediastinal lymph node biopsy, which revealed a benign intravascular papillary endothelial hyperplasia (IPEH). Over five years post-diagnosis and more than four years after transplantation, the patient remains in complete remission with full functional recovery. Conclusions: This case highlights the diagnostic and molecular challenges of HS and demonstrates the curative potential of early allogeneic HSCT, even when only partial remission is initially achieved.

PURPOSE: Newly approved drugs and combinations treating multiple myeloma (MM) have resulted in substantial improvements in patients' survival. To deliver rapid access to newer therapies, an earlier end point to expedite clinical trials is needed. Our objective was to evaluate the minimal residual disease–negative complete response (MRD-CR) as an intermediate end point for progression-free survival (PFS) and overall survival (OS) in newly diagnosed (ND) transplant-eligible (NDTE) patients, ND transplant-ineligible (NDTinE) patients, and patients with relapsed/refractory (RR) MM. PATIENTS AND METHODS: Individual patient data from 20 randomized multicenter trials were collected. Eleven studies (4,773 patients) with sufficient data were analyzed to evaluate whether 9- or 12-month MRD-CR classified at a 10 ^–5 threshold could be reasonably likely to predict the clinical benefit of new agents regarding PFS and OS. Global odds ratio (OR) was estimated using the bivariate Plackett Copula model. Supportive evaluation included correlations of the treatment effects on MRD-CR end points and PFS/OS, evaluated by both linear regression ( R ² _{weighted least squared} ) and Copula ( R ² _Copula ) models. RESULTS: The analysis demonstrated that both 9- and 12-month MRD-CR strongly correlated with PFS at patient level in NDTE patients, NDTinE patients, and patients with RRMM. Global ORs ranged from 3.06 to 16.24, all with 95% CIs excluding 1.0. Encouraging trial-level correlations ( R ² , 0.61-0.70) were observed by pooling three populations and were stronger ( R ² , 0.67-0.78) in the ND population. Similar results were observed for OS. CONCLUSION: Our findings provided the support for use of MRD-CR classified at a 10 ^–5 threshold at either 9 or 12 months after starting of the treatment, as an intermediate end point to support accelerated approvals, in future trials in NDTE patients, NDTinE patients, and patients with RRMM.

The prognostic impact of achieving and in particular maintaining measurable residual disease (MRD) negativity in multiple myeloma is now established; therefore, identifying among MRD-negative patients the ones at higher risk of losing MRD negativity is of importance. We analyzed predictors of unsustained MRD negativity in patients enrolled in the FORTE trial (NCT02203643). MRD was performed by multiparameter flow cytometry (sensitivity of 10−5) at premaintenance and every 6 months thereafter. The cumulative incidence (CI) of MRD resurgence and/or progression was analyzed in MRD-negative patients. A total of 306 of 474 (65%) MRD-negative patients were analyzed. After a median follow-up of 50.4 months from MRD negativity, 185 of 306 (60%) patients were still MRD negative and progression free, 118 (39%) lost their MRD-negative status, and 3 patients (1%) died without progression. Amp1q vs normal (4-year CI, 63% vs 34), ≥2 concomitant high-risk cytogenetic abnormalities vs 0 (4-year CI, 59% vs 33%), circulating tumor cells at baseline (high vs low at 4-year CI, 62% vs 32%), and time-to-reach MRD negativity postconsolidation vs preconsolidation (4-year CI, 46% vs 35%) were associated with a higher risk of unsustained MRD negativity in a multivariate Fine-Gray model. During the first 2 years of maintenance, patients receiving carfilzomib-lenalidomide vs lenalidomide alone had a lower risk of unsustained MRD negativity (4-year CI, 20% vs 33%).

Patients with newly diagnosed multiple myeloma (NDMM) ineligible for autologous stem cell transplantation (ASCT) have lower survival rates and may benefit from frontline regimens that include novel agents. This Phase 1b study (NCT02513186) evaluated preliminary efficacy, safety, and pharmacokinetics (PK) of isatuximab, an anti-CD38 monoclonal antibody, combined with bortezomib-lenalidomide-dexamethasone (Isa-VRd) in patients with NDMM ineligible for/with no intent for immediate ASCT. Overall, 73 patients received four 6-week induction cycles of Isa-VRd, then maintenance with Isa-Rd in 4-week cycles. In the efficacy population (n = 71), the overall response rate was 98.6%, with 56.3% achieving a complete response or better (sCR/CR), and 36/71 (50.7%) patients reaching minimal residual disease negativity (10⁻⁵ sensitivity). Grade ≥3 treatment-emergent adverse events (TEAEs) occurred in 79.5% (58/73) of patients but TEAEs leading to permanent study treatment discontinuation were reported in 14 (19.2%) patients. Isatuximab PK parameters were within the previously reported range, suggesting that VRd does not alter the PK of isatuximab. These data support additional studies of isatuximab in NDMM, such as the Phase 3 IMROZ study (Isa-VRd vs VRd).

PURPOSE: High levels of circulating tumor plasma cells (CTC-high) in patients with multiple myeloma are a marker of aggressive disease. We aimed to confirm the prognostic impact and identify a possible cutoff value of CTC-high for the prediction of progression-free survival (PFS) and overall survival (OS), in the context of concomitant risk features and minimal residual disease (MRD) achievement.METHODS: CTC were analyzed at diagnosis with two-tube single-platform flow cytometry (sensitivity 4 × 10^–5) in patients enrolled in the multicenter randomized FORTE clinical trial (ClinicalTrials.gov identifier: NCT02203643 ). MRD was assessed by second-generation multiparameter flow cytometry (sensitivity 10^–5). We tested different cutoff values in series of multivariate (MV) Cox proportional hazards regression analyses on PFS outcome and selected the value that maximized the Harrell's C-statistic. We analyzed the impact of CTC on PFS and OS in a MV analysis including baseline features and MRD negativity.RESULTS: CTC analysis was performed in 401 patients; the median follow-up was 50 months (interquartile range, 45-54 months). There was a modest correlation between the percentage of CTC and bone marrow plasma cells ( r = 0.38). We identified an optimal CTC cutoff of 0.07% (approximately 5 cells/µL, C-index 0.64). In MV analysis, CTC-high versus CTC-low patients had significantly shorter PFS (hazard ratio, 2.61; 95% CI, 1.49 to 2.97, P < .001; 4-year PFS 38% v 69%) and OS (hazard ratio, 2.61; 95% CI, 1.49 to 4.56; P < .001; 4-year OS 68% v 92%). The CTC levels, but not the bone marrow plasma cell levels, affected the outcome. The only factor that reduced the negative impact of CTC-high was the achievement of MRD negativity (interaction P = .039).CONCLUSION: In multiple myeloma, increasing levels of CTC above an optimal cutoff represent an easy-to-assess, robust, and independent high-risk factor. The achievement of MRD negativity is the most important factor that modulates their negative prognostic impact.

The current strategies for the treatment of multiple myeloma (MM) have improved, thanks to effective drug classes and combination therapies, for both the upfront and relapsed settings. Clinical trials for newly diagnosed transplant-ineligible patients led to the approval of immunomodulatory drugs (IMiDs) and proteasome inhibitors (PIs) in combination with anti-CD38 monoclonal antibodies (mAbs), to be administered during the induction phase before transplantation and during maintenance treatment, with lenalidomide recommended until relapse. In relapsed/refractory patients, the complex treatment scenario currently includes several options, such as triplets with anti-CD38 mAbs plus IMiDs or PIs, and novel targeted molecules. Comparisons among clinical trials and real-world data showed a good degree of reproducibility of some important results, particularly in terms of overall response rate, progression-free survival, and overall survival. This may help clinicians towards a proper selection of the best treatment options, particularly in real-world settings. However, as compared with the management of real-world settings, clinical trials have some pitfalls in terms of outcome and especially in terms of safety and quality of life. In fact, trials include younger and presumably healthier patients, excluding those with worst clinical conditions due to MM features (e.g., renal insufficiency or bone disease, which can impair the performance status) and comorbidities (e.g., cardiac and pulmonary disease), thus resulting in a possible lack of representativeness of data about the patients enrolled. In this review, we analyze comparable and discrepant results from clinical trials vs. real-world settings published in the last 10 years, focusing on different drugs and combinations for the treatment of MM and providing an overview of treatment choices.

PURPOSE: To address the role of consolidation treatment for newly diagnosed, transplant eligible patients with multiple myeloma in a controlled clinical trial. PATIENTS AND METHODS: The EMN02/HOVON95 trial compared consolidation treatment with two cycles of bortezomib, lenalidomide, and dexamethasone (VRD) or no consolidation after induction and intensification therapy, followed by continuous lenalidomide maintenance. Primary study end point was progression-free survival (PFS). RESULTS: Eight hundred seventy-eight eligible patients were randomly assigned to receive VRD consolidation (451 patients) or no consolidation (427 patients). At a median follow-up of 74.8 months, median PFS with adjustment for pretreatment was prolonged in patients randomly assigned to VRD consolidation (59.3 v 42.9 months, hazard ratio [HR] = 0.81; 95% CI, 0.68 to 0.96; P = .016). The PFS benefit was observed across most predefined subgroups, including revised International Staging System (ISS) stage, cytogenetics, and prior treatment. Revised ISS3 stage (HR, 2.00; 95% CI, 1.41 to 2.86) and ampl1q (HR, 1.67; 95% CI, 1.37 to 2.04) were significant adverse prognostic factors. The median duration of maintenance was 33 months (interquartile range 13-86 months). Response ≥ complete response (CR) after consolidation versus no consolidation before start of maintenance was 34% versus 18%, respectively ( P < .001). Response ≥ CR on protocol including maintenance was 59% with consolidation and 46% without ( P < .001). Minimal residual disease analysis by flow cytometry in a subgroup of 226 patients with CR or stringent complete response or very good partial response before start of maintenance demonstrated a 74% minimal residual disease–negativity rate in VRD-treated patients. Toxicity from VRD was acceptable and manageable. CONCLUSION: Consolidation treatment with VRD followed by lenalidomide maintenance improves PFS and depth of response in newly diagnosed patients with multiple myeloma as compared to maintenance alone.

Minimal residual disease (MRD) by multiparameter flow cytometry (MFC) is the most effective tool to define a deep response in multiple myeloma (MM). We conducted an MRD correlative study of the EMN02/HO95 MM phase III trial in newly diagnosed MM patients achieving a suspected complete response before maintenance and every 6 months during maintenance. Patients received high-dose melphalan (HDM) versus bortezomib-melphalan-prednisone (VMP) intensification, followed by bortezomib-lenalidomide-dexamethasone (VRd) versus no consolidation, and lenalidomide maintenance. Bone marrow (BM) samples were processed in three European laboratories, applying EuroFlow-based MFC protocols (eight colors, two tubes) with 10⁻⁴−10⁻⁵ sensitivity. At enrollment in the MRD correlative study, 76% (244/321) of patients were MRD-negative. In the intention-to-treat analysis, after a median follow-up of 75 months, 5-year progression-free survival was 66% in MRD-negative versus 31% in MRD-positive patients (HR 0.39; p < 0.001), 5-year overall survival was 86% versus 69%, respectively (HR 0.41; p < 0.001). MRD negativity was associated with reduced risk of progression or death in all subgroups, including ISS-III (HR 0.37) and high-risk fluorescence in situ hybridization (FISH) patients (HR 0.38;). In the 1-year maintenance MRD population, 42% of MRD-positive patients at pre-maintenance became MRD-negative after lenalidomide exposure. In conclusion, MRD by MFC is a strong prognostic factor. Lenalidomide maintenance further improved MRD-negativity rate.

We analyzed variations in terms of chromosomal abnormalities (CA) by fluorescence in situ hybridization (FISH) analysis on purified bone marrow plasma cells throughout the progression from monoclonal gammopathy of undetermined significance/smoldering multiple myeloma (MGUS/SMM) to newly diagnosed MM/plasma cell leukemia (NDMM/PCL) at diagnosis and from diagnostic samples to progressive disease. High risk was defined by the presence of at least del(17p), t(4;14), and/or t(14;16). 1p/1q detection (in the standard FISH panel from 2012 onward) was not available for all patients. We analyzed 139 MM/PCL diagnostic samples from 144 patients, with a median follow-up of 71 months: high-risk CA at diagnosis (MGUS/SMM or NDMM) was present in 28% of samples, whereas 37–39% showed high-risk CA at relapse. In 115 patients with NDMM who evolved to relapsed/refractory MM, we identified 3 different populations: (1) 31/115 patients (27%) with gain of new CA (del13, del17p, t(4;14), t(14;16) or 1q CA when available); (2) 10/115 (9%) patients with loss of a previously identified CA; and (3) 74 patients with no changes. The CA gain group showed a median overall survival of 66 months vs. 84 months in the third group (HR 0.56, 95% CI 0.34–0.92, p = 0.023). Clonal evolution occurs as disease progresses after different chemotherapy lines. Patients who acquired high-risk CA had the poorest prognosis. Our findings highlight the importance of performing FISH analysis both at diagnosis and at relapse.