Outcomes of Human Leukocyte Antigen-Matched Related Donor and Haploidentical Allogeneic Hematopoietic Cell Transplantation Recipients by Immune Profiles of Recipients and Donors.

Haploidentical (Haplo) allogeneic HCTs (alloHCT) have been used more frequently over the last decade as survival is similar to HLA-matched related donor (MRD) alloHCTs. We aimed to identify donor and recipient immune signatures before alloHCT that are associated with clinically meaningful outcomes in MRD vs Haplo alloHCT recipients. This retrospective cohort study of 165 MRD (n = 132) and Haplo (n = 33) alloHCT recipients and their related donors between 2007-2019 with paired peripheral blood samples immunophenotyped for T-cell, B-cell, NK cell and dendritic cell (DC) subsets. Immune cells were quantified before alloHCT in donors and recipients; calculations of immune cell ratios were classified as high, intermediate, and low and analyzed with alloHCT outcomes. Haplo donors were younger than MRD donors (median: 35 vs 51 years), whereas Haplo recipients were older than MRD recipients (median: 68 vs 54 years), were more likely to have a Karnofsky Performance Score ≤ 70 (76% vs 57%), 3+ comorbidities (54% vs 47%), and were in complete remission prior to alloHCT (58% vs 42%). In MRD alloHCT, a lower ratio of CD4+ to CD8+ effector memory cells in the donor was associated with lower 4-yr overall survival (OS; 25% vs 61%; P = .009), lower 4-yr progression free survival (PFS; 25% vs 58%; P = .014) and higher incidence of 1-yr transplant-related mortality (TRM; 39% vs 7%; P = .009) in recipients. A higher ratio of CD8+ effector memory to total NK cells measured in MRD recipients was associated with a higher incidence of grade II-IV aGvHD (63% vs 37%; P = .004) but was not statistically significant for III-IV aGvHD (23% vs 12%). In Haplo alloHCT, a lower ratio of total T-regulatory to CD4+ central memory cells in the donor was associated with lower 4-yr PFS (22% vs 60%; P = .0091). A higher ratio of CD4+ effector memory to CD8+ effector memory cells measured in Haplo recipients pre-alloHCT was associated with lower 4-yr OS (25% vs 88%; P = .0039). In both MRD and Haplo recipients, a higher ratio of CD4+ naïve to CD4+ central memory cells was associated with a higher incidence of grade II-IV aGvHD (64% vs 38%; P = .04). Evaluation of pre-alloHCT immune signatures of the donor and recipient may influence clinically meaningful patient outcomes in both MRD and Haplo transplants.

Minimal Residual Disease Status in Multiple Myeloma 1 Year After Autologous Hematopoietic Cell Transplantation and Lenalidomide Maintenance Are Associated With Long-Term Overall Survival.

PURPOSE: Prognostic Immunophenotyping in Myeloma Response (PRIMeR) is an ancillary study of minimal residual disease (MRD) assessment for multiple myeloma by next-generation multiparameter flow cytometry (MFC). Patients were enrolled on a three-arm randomized control trial (Blood and Marrow Transplants Clinical Trials Network 0702 Stem Cell Transplant for Myeloma in Combination of Novel Agents [STaMINA]; ClinicalTrials.gov identifier: NCT01109004). METHODS: Four hundred and thirty-five patients consented to the MRD panel, which included 10 monoclonal antibodies measured via six-color MFC. MRD was measured at baseline/preautologous hematopoietic cell transplant (BL/preAutoHCT), premaintenance (PM), and 1 year (Y1) after AutoHCT with a sensitivity of 10-5 to 10-6. The primary objective was to assess MRD-negative (MRDneg) at 1 year after AutoHCT and progression-free survival and overall survival (PFS/OS). RESULTS: Similar to the STaMINA results, at a median follow-up of 70 months, there was no significant difference in PFS/OS by treatment arm in the PRIMeR patients. MRDneg at all three time points was associated with significantly improved PFS, and MRDneg at Y1 had significantly longer OS. Multivariate analysis of PFS, adjusting for disease risk and treatment arm, demonstrated hazard ratios (HRs) in MRD-positive patients compared with MRDneg patients at BL, PM, and Y1 of 1.55 (P = .0074), 1.83 (P = .0007), and 3.61 (P < .0001), respectively. Corresponding HRs for OS were 1.19 (P = .48), 0.88 (P = .68), and 3.36 (P < .001). Patients with sustained MRDneg or who converted to MRDneg by Y1 had similar PFS/OS. CONCLUSION: To our knowledge, this first, prospective US cooperative group, multicenter study demonstrates that MRDneg at Y1 after AutoHCT with lenalidomide maintenance is prognostic for improved 6-year PFS and OS. Serial MRD measurements may direct trials to test how further therapy may improve long-term PFS and OS.

T Cell Exhaustion Markers in Multiple Myeloma Patients are Lower After Physical Activity Intervention.

PURPOSE: There is compelling evidence that CD4+ and CD8+T cells are dysfunctional in multiple myeloma, compromising their ability to control disease progression. Pre-clinical models suggest that exercise represents a non-pharmacologic means to reduce immune exhaustion, but no studies to date have examined the relationship between an exercise intervention and biomarkers of immune exhaustion in multiple myeloma patients. PATIENTS AND METHODS: The current study includes 24 multiple myeloma patients who participated in a six-month physical activity intervention, consisting of supervised strength training (n = 12) and unsupervised home-based walking arms (n = 12). Comprehensive flow cytometry was utilized to assess the frequency of CD4+ and CD8+T cells and subpopulations expressing the markers of exhaustion PD-1, TIGIT, TIM3 and/or LAG3. Ratios of exhausted to non-exhausted cell populations, and percentages of exhausted to total populations of the same lineage, were calculated for the baseline and final timepoints. RESULTS: Eighteen of 20 exhaustion measures were lower at the end of the intervention than at baseline, and several were significantly or borderline significantly reduced in the entire sample or in one of the arms. The entire sample saw improvements in the ratios of CD4+ TIGIT+ to non-exhausted CD4+ (0.7 [0.6] to 0.6 [0.4], P = .04) and CD8+ PD1+ to non-exhausted CD8+ (1.8 [2.6] to 1.5 [2.0], P = .06), and in total exhausted CD8+ as a percent of total CD8+ (72.9 [21.9] to 68.3 [19.6], P < .01). CONCLUSIONS: This pilot study suggests that physical activity induces changes in MM patients' immune systems, potentially rendering a less exhausted T cell state.

Probing cell proliferation: Considerations for dye selection.

Broadly speaking, cell tracking dyes are fluorescent compounds that bind stably to components on or within the cells so the fate of the labeled cells can be followed. Their staining should be bright and homogeneous without affecting cell function. For purposes of monitoring cell proliferation, each time a cell divides the intensity of cell tracking dye should diminish equally between daughter cells. These dyes can be grouped into two different classes. Protein reactive dyes label cells by reacting covalently but non-selectively with intracellular proteins. Carboxyfluorescein diacetate succinimidyl ester (CFSE) is the prototypic general protein label. Membrane intercalating dyes label cells by partitioning non-selectively and non-covalently within the plasma membrane. The PKH membrane dyes are examples of lipophilic compounds whose chemistry allows for their retention within biological membranes without affecting cellular growth, viability, or proliferation when used properly. Here we provide considerations based for labeling cell lines and peripheral blood mononuclear cells using both classes of dyes. Examples from optimization experiments are presented along with critical aspects of the staining procedures to help mitigate common risks. Of note, we present data where a logarithmically growing cell line is labeled with both a protein dye and a membrane tracking dye to compare dye loss rates over 6days. We found that dual stained cells paralleled dye loss of the corresponding single stained cells. The decrease in fluorescence intensity by protein reactive dyes, however, was more rapid than that with the membrane reactive dyes, indicating the presence of additional division-independent dye loss.

Monitoring Cell Proliferation by Dye Dilution: Considerations for Panel Design.

High dimensional studies that include proliferation dyes face two inherent challenges in panel design. First, the more rounds of cell division to be monitored based on dye dilution, the greater the starting intensity of the labeled parent cells must be in order to distinguish highly divided daughter cells from background autofluorescence. Second, the greater their starting intensity, the more difficult it becomes to avoid spillover of proliferation dye signal into adjacent spectral channels, with resulting limitations on the use of other fluorochromes and ability to resolve dim signals of interest. In the third and fourth editions of this series, we described the similarities and differences between protein-reactive and membrane-intercalating dyes used for general cell tracking, provided detailed protocols for optimized labeling with each dye type, and summarized characteristics to be tested by the supplier and/or user when validating either dye type for use as a proliferation dye. In this fifth edition, we review: (a) Fundamental assumptions and critical controls for dye dilution proliferation assays; (b) Methods to evaluate the effect of labeling on cell growth rate and test the fidelity with which dye dilution reports cell division; and. (c) Factors that determine how many daughter generations can be accurately included in proliferation modeling. We also provide an expanded section on spectral characterization, using data collected for three protein-reactive dyes (CellTrace™ Violet, CellTrace™ CFSE, and CellTrace™ Far Red) and three membrane-intercalating dyes (PKH67, PKH26, and CellVue® Claret) on three different cytometers to illustrate typical decisions and trade-offs required during multicolor panel design. Lastly, we include methods and controls for assessing regulatory T cell potency, a functional assay that incorporates the "know your dye" and "know your cytometer" principles described herein.

Using Artificial Intelligence to Interpret Clinical Flow Cytometry Datasets for Automated Disease Diagnosis and/or Monitoring.

Flow cytometry (FC) is routinely used for hematological disease diagnosis and monitoring. Advancement in this technology allows us to measure an increasing number of markers simultaneously, generating complex high-dimensional datasets. However, current analytic software and methods rely on experienced analysts to perform labor-intensive manual inspection and interpretation on a series of 2-dimensional plots via a complex, sequential gating process. With an aggravating shortage of professionals and growing demands, it is very challenging to provide the FC analysis results in a fast, accurate, and reproducible way. Artificial intelligence has been widely used in many sectors to develop automated detection or classification tools. Here we describe a type of machine learning method for developing automated disease classification and residual disease monitoring on clinical flow datasets.

Galectin-3 predicts acute GvHD and overall mortality post reduced intensity allo-HCT: a BMT-CTN biorepository study.

Identifying plasma biomarkers early after allo-HCT may become crucial to prevent and treat severe aGvHD. We utilized samples from 203 allo-HCT patients selected from the Blood & Marrow Transplant Clinical Trials Network (BMT CTN) to identify new biomarker models to predict aGvHD and overall mortality. Two new biomarkers (Gal-3 and LAG-3), and previously identified biomarkers (ST2/IL33R, IL6, Reg3A, PD-1, TIM-3, TNFR1) were screened. Increased Gal-3 levels measured at Day +7 post-transplant predicted the development of aGvHD (grade 2-4) in the total population [AUC: 0.602; P = 0.045] while higher Day +14 levels predicted overall mortality due to toxicity among patients receiving reduced intensity conditioning [P = 0.028] but not myeloablative conditioning. Elevated LAG-3 levels (Day +21) were associated with less severe aGvHD [159.1 ng/mL vs 222.0 ng/mL; P = 0.046]. We developed a model utilizing Gal-3, LAG-3, and PD-1 levels at Days +14 and +21 with an improved performance to predict aGvHD and overall non-relapse mortality. We confirmed four informative biomarkers (Reg3A, ST2, TIM-3, and TNFR1) predict severe aGvHD at day +14 and day +21 (grade 3-4). In conclusion, the combination of Gal-3 alone or in combination with LAG-3, and PD-1 is a new informative model to predict aGvHD development and overall non-relapse mortality after allo-HCT.

Systemic infusion of TLR3-ligand and IFN-α in patients with breast cancer reprograms local tumor microenvironments for selective CTL influx.

BACKGROUND: Presence of cytotoxic T lymphocytes (CTL) in the tumor microenvironment (TME) predicts the effectiveness of cancer immunotherapies. The ability of toll-like receptor 3 (TLR3) ligands, interferons (IFNs) and COX2 inhibitors to synergistically induce CTL-attracting chemokines (but not regulatory T cell (Treg)-attractants) in the TME, but not in healthy tissues, observed in our preclinical studies, suggested that their systemic application can reprogram local TMEs. METHODS: Six evaluable patients (33-69 years) with metastatic triple-negative breast cancer received six doses of systemic chemokine-modulating (CKM) regimen composed of TLR3 ligand (rintatolimod; 200 mg; intravenous), IFN-α2b (20 MU/m2; intravenous) and COX2 inhibitor (celecoxib; 2×200 mg; oral) over 2 weeks. The predetermined primary endpoint was the intratumoral change in the expression of CTL marker, CD8α, in the post-CKM versus pre-CKM tumor biopsies. Patients received follow-up pembrolizumab (200 mg, intravenously, every 3 weeks), starting 3-8 days after completion of CKM. RESULTS: Post-CKM biopsies showed selectively increased CTL markers CD8α (average 10.2-fold, median 5.5-fold, p=0.034) and granzyme B (GZMB; 6.1-fold, median 5.8-fold, p=0.02), but not FOXP3 (Treg marker) relative to HPRT1 expression, resulting in the increases in average CD8α/FOXP3 ratio and GZMB/FOXP3 ratio. CKM increased intratumoral CTL-attractants CCL5 and CXCL10, but not Treg-attractants CCL22 or CXCL12. In contrast, CD8+ T cells and their CXCR3+ subset showed transient decreases in blood. One clinical response (breast tumor autoamputation) and three stable diseases were observed. The patient with clinical response remains disease free, with a follow-up of 46 months as of data cut-off. CONCLUSIONS: Short-term systemic CKM selectively increases CTL numbers and CTL/Treg ratios in the TME, while transiently decreasing CTL numbers in the blood. Transient effects of CKM suggest that its simultaneous application with checkpoint blockade and other forms of immunotherapy may be needed for optimal outcomes.

Tumor and immune remodeling following radiotherapy in human renal cell carcinoma.

BACKGROUND: Studies evaluating peripheral patient samples show radiation can modulate immune responses, yet the biological changes in human tumors particularly at the cellular level remain largely unknown. Here, we address how radiation treatment shapes the immune compartment and interactions with cancer cells within renal cell carcinoma (RCC) patient tumors. METHODS: To identify how radiation shaped the immune compartment and potential immune interactions with tumor cells we evaluated RCC tumors from patients treated only with nephrectomy or with radiation followed by nephrectomy. Spectral flow cytometry using a 35-marker panel was performed on cell suspensions to evaluate protein expression within immune subsets. To reveal how radiation alters programming of immune populations and interactions with tumor cells, we examined transcriptional changes by single-cell RNA sequencing (scRNAseq). RESULTS: Spectral flow cytometry analysis revealed increased levels of early-activated as well as effector programmed cell death protein-1 (PD-1)+ CD8 T-cell subsets within irradiated tumors. Following quality control, scRNAseq of tumor samples from nephrectomy-only or radiation followed by nephrectomy-treated patients generated an atlas containing 34,626 total cells. Transcriptional analysis revealed increased transition from stem-like T-cell populations to effector T cells in irradiated tumors. Interferon (IFN) pathways, that are central to radiation-induced immunogenicity, were enriched in irradiated lymphoid, myeloid, and cancer cell populations. Focused cancer cell analysis showed enhanced antigen presentation and increased predicted TRAIL-mediated and IFN-mediated interactions between tumor cells and the same effector T-cell subsets increased by radiation. TRAIL and IFN pathways enriched in irradiated tumors were associated with survival in patients treated with immunotherapy. CONCLUSIONS: These findings identify the source of IFN enrichment within irradiated RCC and reveal heightened levels of PD-1+ CD8+ T-cell subsets and increased probability of interactions with tumor cells following standalone radiation treatment. This study provides a window into the irradiated tumor-immune microenvironment of patients and rationale for treatment combinations.

Spatiotemporal assessment of immunogenomic heterogeneity in multiple myeloma.

Spatial heterogeneity is a common phenomenon in metastatic solid tumors and an evolving concept in multiple myeloma (MM). The interplay between malignant plasma cells (PCs) and the microenvironment has not yet been analyzed in MM. For this purpose, we performed bone marrow aspirates and imaging-guided biopsies of corresponding lesions in newly diagnosed MM (NDMM) and relapsed/refractory MM (RRMM) patients. PCs were isolated and subjected to whole-exome sequencing (WES). Non-PCs were studied with next-generation flow (NGF) and T-cell receptor sequencing (TCRseq) to analyze the connection between malignant and nonmalignant cells in the bone marrow and in lesions. Although we observed a strong overlap from WES, NGF, and TCRseq in patients with intramedullary disease, WES revealed significant spatial heterogeneity in patients with extramedullary disease. NGF showed significant immunosuppression in RRMM compared with NDMM as indicated by fewer myeloid dendritic cells, unswitched memory B cells, Th9 cells, and CD8 effector memory T cells but more natural killer and regulatory T cells. Additionally, fewer T-cell receptor (TCR) sequences were detected in RRMM compared with NDMM and healthy individuals. After induction therapy, TCR repertoire richness increased to levels of healthy individuals, and NGF showed more regulatory T cells and myeloid-derived suppressor cells, regardless of depth of response. Clinical significance of imaging-guided biopsies of lesions was demonstrated by detection of monoclonal PCs in patients without measurable residual disease (MRD) in aspirates from the iliac crest as well as identification of secondary primary malignancies in MRD- patients. Furthermore, site-specific clones with different drug susceptibilities and genetically defined high-risk features were detected by our workflow.

Augmenting antibody response to EGF-depleting immunotherapy: Findings from a phase I trial of CIMAvax-EGF in combination with nivolumab in advanced stage NSCLC.

Background: CIMAvax-EGF is an epidermal growth factor (EGF)-depleting immunotherapy which has shown survival benefit as a switch maintenance treatment after platinum-based chemotherapy in advanced non-small cell lung cancer (NSCLC). The primary objective of this trial is to establish the safety and recommended phase II dose (RP2D) of CIMAvax-EGF in combination with nivolumab as second-line therapy for NSCLC. Methods: Patients with immune checkpoint inhibitor-naive metastatic NSCLC were enrolled using a "3+3" dose-escalation design. Toxicities were graded according to CTCAE V4.03. Thirteen patients (one unevaluable), the majority with PD-L1 0%, were enrolled into two dose levels of CIMAvax-EGF. Findings: The combination was determined to be safe and tolerable. The recommended phase 2 dose of CIMAvax-EGF was 2.4 mg. Humoral response to CIMAvax-EGF was achieved earlier and in a greater number of patients with the combination compared to historical control. Four out of 12 evaluable patients had an objective response.

Development of a 27-color panel for the detection of measurable residual disease in patients diagnosed with acute myeloid leukemia.

Acute myeloid leukemia (AML) measurable residual disease (MRD) evaluated by multiparametric flow cytometry (MFC) is a surrogate for progression-free and overall survival in clinical trials and patient management. Due to the limited number of detection channels available in conventional flow cytometers, panels used for assessing AML MRD are typically split into multiple tubes. This cripples the simultaneous and correlated assessment of all myeloblast measurements. In response, we prototyped a single-tube 27-color MFC assay for the evaluation of AML MRD, incorporating all recommended markers. Marrow aspirates from 22 patients were processed for analysis using full spectrum flow cytometry (FSFC). The signal resolution of each marker was compared between samples stained with single antibody vs. the fully stained panel. The analytical accuracy for quantifying hematopoietic cells between our established 8-color assay and the new 27-color method were compared. Variations within an operator and between separate operators were assessed to evaluate the assays reproducibility. The limited of blank (LOB), limit of detection (LOD), and lower limit of quantification (LLOQ) of the 27-color method were empirically determined using limiting dilution experiments. The stability of antibody cocktails over a period of 120 h was also studied using cryopreserved marrow cells. The stain indices for all antibodies were lower in the fully stained panel compared to cells stained with one antibody but clear separations between negative and positive signals were achieved for all antibodies. Our results demonstrated a high concordance between the established 8-color method and the new 27-color assay for enumerating myeloblasts and MRD interpretation within and between operators. The data further showed that the single-tube 27-color assay easily achieved the minimum required detection sensitivity of 0.1%. When antibodies were combined, however, expression intensity of some antigens deteriorated significantly when stored. Our single-tube 27-color panel is a suitable, high sensitivity flow cytometric approach that can be used for AML MRD testing, which improves the correlation of aberrant antigens and detection of asynchronous differentiation patterns. Based on the stability study, we recommend the full panel be made prior to staining.

Mass-Fix better predicts for PFS and OS than standard methods among multiple myeloma patients participating on the STAMINA trial (BMT CTN 0702 /07LT).

Measuring response among patients with multiple myeloma is essential for the care of patients. Deeper responses are associated with better progression free survival (PFS) and overall survival (OS). To test the hypothesis that Mass-Fix, a mass spectrometry-based means to detect monoclonal proteins, is superior to existing methodologies to predict for survival outcomes, samples from the STAMINA trial (NCT01109004), a trial comparing three transplant approaches, were employed. Samples from 575 patients from as many as three time points (post-induction [post-I; pre-maintenance [pre-M]; 1 year post enrollment [1YR]) were tested when available. Four response parameters were assessed: Mass-Fix, serum immunofixation, complete response, and measurable residual disease (MRD) by next generation flow cytometry. Of the four response measures, only MRD and Mass-Fix predicted for PFS and OS at multiple testing points on multivariate analyses. Although MRD drove Mass-Fix from the model for PFS at post-I and pre-M, 1YR Mass-Fix was independent of 1YR MRD. For OS, the only prognostic pre-I measure was Mass-Fix, and the only 1YR measures that were prognostic on multivariate analysis were 1YR MRD and 1YR Mass-Fix. SIFE and CR were not. Mass-Fix is a powerful means to track response.

Deciphering spatial genomic heterogeneity at a single cell resolution in multiple myeloma.

Osteolytic lesions (OL) characterize symptomatic multiple myeloma. The mechanisms of how malignant plasma cells (PC) cause OL in one region while others show no signs of bone destruction despite subtotal infiltration remain unknown. We report on a single-cell RNA sequencing (scRNA-seq) study of PC obtained prospectively from random bone marrow aspirates (BM) and paired imaging-guided biopsies of OL. We analyze 148,630 PC from 24 different locations in 10 patients and observe vast inter- and intra-patient heterogeneity based on scRNA-seq analyses. Beyond the limited evidence for spatial heterogeneity from whole-exome sequencing, we find an additional layer of complexity by integrated analysis of anchored scRNA-seq datasets from the BM and OL. PC from OL are characterized by differentially expressed genes compared to PC from BM, including upregulation of genes associated with myeloma bone disease like DKK1, HGF and TIMP-1 as well as recurrent downregulation of JUN/FOS, DUSP1 and HBB. Assessment of PC from longitudinally collected samples reveals transcriptional changes after induction therapy. Our study contributes to the understanding of destructive myeloma bone disease.

Ofatumumab plus HyperCVAD/HD-MA induction leads to high rates of minimal residual disease negativity in patients with newly diagnosed mantle cell lymphoma: Results of a phase 2 study.

BACKGROUND: Ofatumumab is a humanized type 1 anti-CD20 monoclonal antibody. Preclinical studies show improved complement-mediated cytotoxicity (CMC) compared to rituximab in mantle cell lymphoma (MCL). This study evaluates the safety and efficacy of combining ofatumumab with HyperCVAD/MA (O-HyperCVAD) in newly diagnosed MCL. METHODS: In this single-arm phase 2 study, 37 patients were treated with the combination of O-HyperCVAD for 4 or 6 cycles, followed by high dose chemotherapy and autologous stem cell transplant. Primary objectives were overall response rate (ORR) and complete response (CR) rate at the end of therapy. Secondary objectives included minimal residual disease (MRD) negativity, progression-free survival (PFS), and overall survival (OS). RESULTS: Median age was 60 years; ORR was 86% and 73% achieved a CR by modified Cheson criteria. The MRD negativity rate was 78% after 2 cycles of therapy, increasing to 96% at the end of induction; median PFS and OS were 45.5 months and 56 months, respectively. Achieving a post-induction CR by both imaging and flow cytometry was associated with improved PFS and OS. Early MRD negativity (post-2 cycles) was also associated with an improved PFS but not OS. There were 3 deaths while on therapy, and grades 3 and 4 adverse events (AEs) were observed in 22% and 68% of the patients. CONCLUSION: The addition of ofatumumab to HyperCVAD/HD-MA led to high rates of MRD negativity by flow cytometry in patients with newly diagnosed MCL. Achieving a CR post-induction by both imaging and flow cytometry is associated with improved overall survival.

Lymphocyte subset abnormalities in early severe scleroderma favor a Th2 phenotype and are not altered by prior immunosuppressive therapy.

OBJECTIVES: The Scleroderma: Cyclophosphamide or Transplantation (SCOT) trial compared hematopoietic stem cell transplant to CYC treatment in patients with early SSc with progressive skin and lung or kidney involvement. Here we describe lymphocyte phenotype abnormalities at study entry and the relation to prior DMARD therapy. METHODS: Lymphocyte subsets (n = 26) measured by flow cytometry were compared in 123 heathy controls and 71 SCOT participants, including those given (n = 57) or not given (n = 14) DMARDs within 12 months of randomization. RESULTS: Compared with healthy controls, individuals with SSc showed significant reductions in central memory CD8 T cells, activated total and CD4 T cells, γ/δ T cells, memory B cells, myeloid and plasmacytoid dendritic cells and FOXP3+CD25+ Treg cells and increases in naïve CD4 T cells, effector memory CD4 T cells and effector CD8 T cells. A greater bias towards a IL-4+ Th2/T cytotoxic 2 (Tc2) phenotype based on the Th2:Th1 CD4 ratio and Tc2:Tc1 CD8 T cells was also found. Notably, no difference in any lymphocyte subset was observed between those given or not given prior DMARDs. CONCLUSIONS: In patients with early, severe SSc, significant lymphocyte subset abnormalities were observed. Prior treatment with immunosuppressive therapy did not impact the immunophenotype, suggesting that lymphocyte disturbances in scleroderma appeared to be due to the disease itself. TRIAL REGISTRATION: ClinicalTrials.gov (https://clinicaltrials.gov), NCT00114530.

Evaluation of multiple myeloma measurable residual disease by high sensitivity flow cytometry: An international harmonized approach for data analysis.

BACKGROUND: Multiple myeloma (MM) measurable residual disease (MRD) evaluated by flow cytometry is a surrogate for progression-free and overall survival in clinical trials. However, analysis and reporting between centers lack uniformity. We designed and evaluated a consensus protocol for MM MRD analysis to reduce inter-laboratory variation in MM MRD reporting. METHODS: Seventeen participants from 13 countries performed blinded analysis of the same eight de-identified flow cytometry files from patients with/without MRD using their own method (Stage 1). A consensus gating protocol was then designed following survey and discussions, and the data re-analyzed for MRD and other bone marrow cells (Stage 2). Inter-laboratory variation using the consensus strategy was reassessed for another 10 cases and compared with earlier results (Stage 3). RESULTS: In Stage 1, participants agreed on MRD+/MRD- status 89% and 68% of the time respectively. Inter-observer variation was high for total numbers of analyzed cells, total and normal plasma cells (PCs), limit of detection, lower limit of quantification, and enumeration of cell populations that determine sample adequacy. The identification of abnormal PCs remained relatively consistent. By consensus method, average agreement on MRD- status improved to 74%. Better consistency enumerating all parameters among operators resulted in near-unanimous agreement on sample adequacy. CONCLUSION: Uniform flow cytometry data analysis substantially reduced inter-laboratory variation in reporting multiple components of the MM MRD assay. Adoption of a harmonized approach would meet an important need for conformity in reporting MM MRD for clinical trials, and wider acceptance of MM MRD as a surrogate clinical endpoint.

Evaluation of measurable residual disease in multiple myeloma by multiparametric flow cytometry: Current paradigm, guidelines, and future applications.

Multiple myeloma (MM) is a heterogeneous group of mature B-cell diseases that are typically characterized by the presence and accumulation of abnormal plasma cells (PCs), which results in the excess production of monoclonal immunoglobulin and/or light chain found in the serum and/or urine. Multiparametric flow cytometry (MFC) is an indispensable tool to supplement the diagnosis, classification and monitoring of the disease due to its high patient applicability, excellent sensitivity and encouraging results from various clinical trials. In this regard, minimal or, more appropriately, measurable residual disease (MRD) negativity by MFC has been recognized as a powerful predictor of favourable long-term outcomes. Before flow cytometry can be effectively implemented in the clinical setting for MM MRD testing, sample preparation, panel configuration, analysis and gating strategies must be optimized to ensure accurate results. This manuscript will discuss the current consensus guidelines for flow cytometric processing of samples and reporting of results for MM MRD testing. We also discuss alternative approaches to detect plasma cells in the presence of daratumumab treatment. Finally, there is a lack of information describing the subclonal distribution of myeloma cells based on their protein expression. The advent of high-dimensional analysis may assist in following the evolution of antigen expression patterns on abnormal plasma cells in patients with relapsed/refractory disease. This in turn can help identify clonal subtypes that are more aggressive for potential informed decision. An analysis using t-SNE to identify the emergence of PCs subclones by MFC, along with the analysis of their immunophenotypic profiles are presented as a future perspective.

CD319 (SLAMF7) an alternative marker for detecting plasma cells in the presence of daratumumab or elotuzumab.

BACKGROUND: Daratumumab is an anti-CD38 immunotherapeutic drug that has increasingly been used to treat patients with heavily pre-treated and relapsed/refractory multiple myeloma. In so doing, the detection of CD38 antigen on plasma cells by flow cytometry is impeded. We hypothesized that alternative markers can be used in place or in addition to CD38 when detecting plasma cells post-treated with daratumumab. METHODS: A total of 16 alternative markers were tested using 22 bone marrow aspirates from patients with plasma cell neoplasm. The ability of selected markers to discern plasma cells from other hematopoietic cells were evaluated. The stability of tested markers when stored at 4 or 25°C after T = 0, 24, 48, and 72 h was also established. Finally, selected markers were incorporated into a panel used for monitoring multiple myeloma measurable residual disease to test their utility to identify plasma cells in the presence of daratumumab and/or elotuzumab (anti-CD319) drugs. RESULTS: Out of the 16 tested markers, CD319, CD54, CD229, CD317, and p63 were expressed by >90% of the plasma cells. Only CD319, CD54, and CD229 achieved 100% detection sensitivity. Further analysis showed that CD319 was better than CD229 and CD54 at resolving plasma cells from background hematopoietic cells, with CD54 being the worst (resolution metric, mean ± SD: CD319 [2.04 ± 0.86]; CD229 [1.47 ± 0.45]; and CD54 [1.22 ± 0.60]). CD229 was expressed by >90% of T lymphocytes, whereas CD319 was expressed preferentially by the CD8+ T cells and less frequently in CD4+ T cells. Additionally, CD229 was found on >60% of B and NK cells, as well as minor subsets of monocytes and granulocytes. CD319 was expressed on most NK cells and a minor subset of B cells, granulocytes, and monocytes. Even though CD229 and CD319 were expressed by different leukocyte subsets, their expression levels were highest on plasma cells. The expression of CD138 on plasma cells was significantly lower after storage at 4°C, while the expression levels of CD38, CD229, and CD319 remained stable at 4 or 25°C. Using limiting dilution experiments, the treatment of cells with daratumumab severely impeded the detection of CD38 antigen on plasma cells, whereas elotuzumab treatment did not block detection of CD319 on plasma cells. CONCLUSIONS: CD319 is a suitable alternative to CD38 for identifying plasma cells. Our results showed that a panel used for monitoring multiple myeloma measurable residual disease could be modified by using CD319 alone or in combination with CD38 to detect PCs in daratumumab or elotuzumab treated patients.