Graft-versus-host disease and impact on relapse in myelofibrosis undergoing hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (alloHSCT) remains the only curative treatment for myelofibrosis (MF). Relapse occurs in 10-30% and remains a major factor for dismal outcomes. Previous work suggested that graft-versus-host disease (GVHD) might be associated with risk of relapse. This study included 341 patients undergoing their first (n = 308) or second (n = 33) alloHSCT. Anti-T-lymphocyte or antithymocyte globulin was used for GVHD prophylaxis in almost all patients. Median time to neutrophile and platelet engraftment was 13 days and 19 days, respectively. The cumulative incidence of acute GVHD grade II-IV was 41% (median, 31 days; range, 7-112). Grade III-IV acute GVHD was observed in 22%. The cumulative incidence of chronic GVHD was 61%. Liver was affected in 23% of acute GVHD cases and 46% of chronic GVHD cases. Severe acute GVHD was associated with high non-relapse mortality. The development of acute GVHD grade II and moderate GVHD was an independent factor for reduced risk for relapse after transplantation without increased risk for non-relapse mortality, while especially acute GVHD grade IV was associated with high non-relapse mortality. Last, we identified that ongoing response to ruxolitinib, accelerated-phase MF at time of transplantation and splenectomy prior to transplantation were independent predictors for relapse.

CD19-targeted chimeric antigen receptor T cell therapy in two patients with multiple sclerosis

BACKGROUND

Progressive multiple sclerosis (MS) is characterized by compartmentalized smoldering neuroinflammation caused by the proliferation of immune cells residing in the central nervous system (CNS), including B cells. Although inflammatory activity can be prevented by immunomodulatory therapies during early disease, such therapies typically fail to halt disease progression. CD19 chimeric antigen receptor (CAR)-T cell therapies have revolutionized the field of hematologic malignancies. Although generally considered efficacious, serious adverse events associated with CAR-T cell therapies such as immune effector cell-associated neurotoxicity syndrome (ICANS) have been observed. Successful use of CD19 CAR-T cells in rheumatic diseases like systemic lupus erythematosus and neuroimmunological diseases like myasthenia gravis have recently been observed, suggesting possible application in other autoimmune diseases.

METHODS

Here, we report the first individual treatment with a fully human CD19 CAR-T cell therapy (KYV-101) in two patients with progressive MS.

FINDINGS

CD19 CAR-T cell administration resulted in acceptable safety profiles for both patients. No ICANS was observed despite detection of CD19 CAR-T cells in the cerebrospinal fluid. In case 1, intrathecal antibody production in the cerebrospinal fluid decreased notably after CAR-T cell infusion and was sustained through day 64.

CONCLUSIONS

CD19 CAR-T cell administration in progressive MS resulted in an acceptable safety profile. CAR-T cell presence and expansion were observed in the cerebrospinal fluid without clinical signs of neurotoxicity, which, along with intrathecal antibody reduction, indicates expansion-dependent effects of CAR-T cells on CD19+ target cells in the CNS. Larger clinical studies assessing CD19 CAR-T cells in MS are warranted.

FUNDING

Both individual treatments as well the generated data were not based on external funding.

Use of ropeginterferon in inducing graft versus myelofibrosis effect in post-transplant myelofibrosis relapse

Here, we describe a patient with post-transplant myelofibrosis with chronic graft-versus-host disease (GVHD), who showed successful molecular remission with ropeginterferon with 100% donor chimerism without any flare up of GVHD. He was initially diagnosed with polycythemia vera (PV) which progressed to myelofibrosis after 6 years. The MYSEC (Myelofibrosis Secondary to PV and ET-Prognostic Model) and MTSS (myelofibrosis transplant scoring system) scores were 13.1 and 4, respectively, and the patient was in intermediate risk group. He underwent an allogenic stem cell transplant; however, his disease gradually progressed and was administered two donor lymphocyte infusions with minimal response. A second allogeneic transplant was performed, which led to a persistent molecular remission for more than a decade, although he developed chronic skin graft-versus-host disease (GVHD). The JAK2 V617F levels started to increase 10 years post-transplant with ongoing chronic GVHD and a corresponding decrease in donor chimerism levels. He was administered ropeginterferon, which led to a decrease in JAK 2617F to undetectable levels. A graft versus myelofibrosis effect was attained with reversal to 100% donor chimerism, and he has since maintained a molecular remission with undetectable JAK 2617F levels. Chronic GVHD made him ineligible for donor lymphocyte infusions later. Thus, ropeginterferon was successful in inducing graft versus myelofibrosis effect, leading to a molecular response with no flare up of GVHD. The use of ropeginterferon needs to be further evaluated in larger cohorts of post-transplant myelofibrosis patients.

Donor Lymphocyte Infusion and Molecular Monitoring for Relapsed Myelofibrosis After Hematopoietic Cell Transplantation

Hematopoietic cell transplantation (HCT) is a curative approach for myelofibrosis patients, but relapse is a major cause of treatment failure. We investigated the effect of donor lymphocyte infusion (DLI) in 37 patients with molecular (n = 17) or hematological relapse (n = 20) after HCT. Patients received median of 2 (range, 1-5) cumulative DLI (total of 91 infusions). Median starting dose was 1 × 10⁶ cells/kg, escalated by half-log ≥6 weeks if no response nor graft-versus-host disease (GvHD) occurred. Median time to first DLI was 40 weeks for molecular relapse versus 145 weeks for hematological relapse. Overall molecular complete response (mCR) at any time was 73% (n = 27) and was significantly higher for initial molecular relapse (88%) versus hematological relapse (60%; P = 0.05). The 6-year overall survival was 77% versus 32% (P = 0.03). Acute GvHD 2-4 occurred in 22% and half of the patients achieved mCR without any GvHD. All patients who relapsed from mCR achieved after first DLI could be salvaged with subsequent DLI, showing long-term survival. No second HCT was needed for molecular relapse versus 6 for hematological relapse. This comprehensive and largest study to date suggests molecular monitoring together with DLI as standard of care and a crucial approach to achieve excellent outcomes in relapsed myelofibrosis.

Impact of TP53 on outcome of patients with myelofibrosis undergoing hematopoietic stem cell transplantation

TP53 mutations (TP53MTs) have been associated with poor outcomes in various hematologic malignancies, but no data exist regarding its role in patients with myelofibrosis undergoing hematopoietic stem cell transplantation (HSCT). Here, we took advantage of a large international multicenter cohort to evaluate the role of TP53MT in this setting. Among 349 included patients, 49 (13%) had detectable TP53MT, of whom 30 showed a multihit configuration. Median variant allele frequency was 20.3%. Cytogenetic risk was favorable (71%), unfavorable (23%), and very high (6%), with complex karyotype present in 36 patients (10%). Median survival of patients with TP53MT was 1.5 vs 13.5 years for those with wild-type TP53 (TP53WT; P < .001). Outcome was driven by multihit TP53MT constellation (P < .001), showing 6-year survival of 56% for individuals with single-hit vs 25% for those with multihit TP53MT vs 64% for those with TP53WT. Outcome was independent of current transplantation-specific risk factors and conditioning intensity. Similarly, cumulative incidence of relapse was 17% for single-hit vs 52% for multihit vs 21% for TP53WT. Ten patients with TP53MT (20%) presented as leukemic transformation vs only 7 (2%) in the TP53WT group (P < .001). Out of the 10 patients with TP53MT, 8 showed multihit constellation. Median time to leukemic transformation was shorter for multihit and single-hit TP53MT (0.7 and 0.5 years, respectively) vs 2.5 years for TP53WT. In summary, multihit TP53MT represents a very high-risk group in patients with myelofibrosis who are undergoing HSCT, whereas single-hit TP53MT alone showed similar outcome to patients with nonmutated TP53, informing prognostication for survival and relapse together with current transplantation-specific tools.

Peripheral and Portal Venous KRAS ctDNA Detection as Independent Prognostic Markers of Early Tumor Recurrence in Pancreatic Ductal Adenocarcinoma

BACKGROUND

KRAS circulating tumor DNA (ctDNA) has shown biomarker potential for pancreatic ductal adenocarcinoma (PDAC) but has not been applied in clinical routine yet. We aim to improve clinical applicability of ctDNA detection in PDAC and to study the impact of blood-draw site and time point on the detectability and prognostic role of KRAS mutations.

METHODS

221 blood samples from 108 PDAC patients (65 curative, 43 palliative) were analyzed. Baseline peripheral and tumor-draining portal venous (PV), postoperative, and follow-up blood were analyzed and correlated with prognosis.

RESULTS

Significantly higher KRAS mutant detection rates and copy numbers were observed in palliative compared to curative patients baseline blood (58.1% vs 24.6%; P = 0.002; and P < 0.001). Significantly higher KRAS mutant copies were found in PV blood compared to baseline (P < 0.05) samples. KRAS detection in pre- and postoperative and PV blood were significantly associated with shorter recurrence-free survival (all P < 0.015) and identified as independent prognostic markers. KRAS ctDNA status was also an independent unfavorable prognostic factor for shorter overall survival in both palliative and curative cohorts (hazard ratio [HR] 4.9, P = 0.011; HR 6.9, P = 0.008).

CONCLUSIONS

KRAS ctDNA detection is an independent adverse prognostic marker in curative and palliative PDAC patients-at all sites of blood draw and a strong follow-up marker. The most substantial prognostic impact was seen for PV blood, which could be an effective novel tool for identifying prognostic borderline patients-guiding future decision-making on neoadjuvant treatment despite anatomical resectability. In addition, higher PV mutant copy numbers contribute to an improved technical feasibility.

Individualized busulfan dosing improves outcomes compared to fixed-dose administration in pre-transplant minimal residual disease-positive acute myeloid leukemia patients with intermediate-risk undergoing allogeneic stem cell transplantation in CR

Pre-transplant minimal residual disease (MRD) impacts negatively on post-transplant relapse risk in acute myeloid leukemia (AML). Therapeutic drug monitoring by calculating area under the curve (AUC) was developed to optimize busulfan (Bu) exposure. Here, we compared post-transplant outcomes after individualized versus fixed busulfan dosage in intermediate-risk AML who achieved CR prior to allograft focusing on pre-transplant flow-MRD. Eighty-seven patients (median, 56 years) with intermediate-risk AML and pre-transplant flow-MRD ("different from normal") were included. Thirty-two patients received individualized busulfan; 54 fixed dosages. Individualized dosage was adjusted in 25/32 patients: increased, n = 18/25 (72%); decreased: n = 7/25 (28%). After median follow-up of 27 months, we observed lower 3-year relapses (6%, 2%-19% vs. 35%, 23%-49% p = 0.02), improved 3-year leukemia-free survival (LFS) (78%, 54%-91% vs. 55%, 40%-70% p = 0.009) and - overall survival (OS) (82%, 60%-93% vs. 69%, 54%-81% p = 0.05) after individualized compared to fixed Bu. Non-relapsed mortality (NRM) and acute graft versus host disease (GvHD) were not different. In multivariate analysis, fixed Bu showed unfavorable impact on OS (hazard ratio [HR] 4.6, p = 0.044), LFS (HR 3.6, p = 0.018) and relapses (HR 3.6, p = 0.033). Fixed Bu also had unfavorable impact on LFS (3.6, 1.1-12.6, p = 0.041) in pre-transplant MRD-positive patients. Individualized, AUC-based, busulfan is associated with lower relapses in intermediate-risk AML patients allografted in CR and may overcome pre-transplant MRD-positivity.

Molecular monitoring of T-cell kinetics and migration in severe neurotoxicity after real-world CD19-specific chimeric antigen receptor T cell therapy

CD19-specific chimeric antigen receptor (CD19-CAR) T-cell therapies mediate durable responses in late-stage B-cell malignancies, but can be complicated by a potentially severe immune effector cell-associated neurotoxicity syndrome (ICANS). Despite broad efforts, the precise mechanisms of ICANS are not entirely known, and resistance to current ICANSdirected therapies (especially corticosteroids) has been observed. Recent data suggest that inflammatory cytokines and/or targeting of cerebral CD19-expressing pericytes can disrupt the blood-brain barrier and facilitate influx of immune cells, including CAR T cells. However, specific tools for CD19-CAR T-cell analysis within often minute samples of cerebrospinal fluid (CSF) are not broadly available. Here, we applied our recently developed digital polymerase chain reaction assays to monitor CD19-CAR T-cell kinetics in CSF and blood in real-world patients with neurotoxicity. Consistently, we observed a CAR T-cell enrichment within CSF in ICANS patients with further progressive accumulation despite intense corticosteroid- containing immuno-chemotherapies in a subset of patients with prolonged and therapy-resistant grade 3-4 neurotoxicity. We used next-generation T-cell receptor-b sequencing to assess the repertoire of treatment-refractory cells. Longitudinal analysis revealed a profound skewing of the T-cell receptor repertoire, which at least partly reflected selective expansion of infused T-cell clones. Interestingly, a major fraction of eventually dominating hyperexpanded T-cell clones were of non-CAR T-cell derivation. These findings hint to a role of therapy-refractory T-cell clones in severe ICANS development and prompt future systematic research to determine if CAR T cells may serve as 'door openers' and to further characterize both CAR-positive and non-CAR T cells to interrogate the transcriptional signature of these possibly pathologic T cells.

Population Pharmacokinetics of Busulfan and Its Metabolite Sulfolane in Patients with Myelofibrosis Undergoing Hematopoietic Stem Cell Transplantation

For patients with myelofibrosis, allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the only curative treatment to date. Busulfan-based conditioning regimens are commonly used, although high inter-individual variability (IIV) in busulfan drug exposure makes individual dose selection challenging. Since data regarding the IIV in patients with myelofibrosis are sparse, this study aimed to develop a population pharmacokinetic (PopPK) model of busulfan and its metabolite sulfolane in patients with myelofibrosis. The influence of patient-specific covariates on the pharmacokinetics of drug and metabolite was assessed using non-linear mixed effects modeling in NONMEM^®. We obtained 523 plasma concentrations of busulfan and its metabolite sulfolane from 37 patients with myelofibrosis. The final model showed a population clearance (CL) and volume of distribution (V_d) of 0.217 L/h/kg and 0.82 L/kg for busulfan and 0.021 L/h/kg and 0.65 L/kg for its metabolite. Total body weight (TBW) and a single-nucleotide polymorphism of glutathione-S-transferase A1 (GSTA1 SNP) displayed a significant impact on volume of distribution and metabolite clearance, respectively. This is the first PopPK-model developed to describe busulfan’s pharmacokinetics in patients with myelofibrosis. Incorporating its metabolite sulfolane into the model not only allowed the characterization of the covariate relationship between GSTA1 and the clearance of the metabolite but also improved the understanding of busulfan’s metabolic pathway.

Digital PCR to quantify ChAdOx1 nCoV-19 copies in blood and tissues

Vaccination with the adenoviral-vector-based AstraZeneca ChAdOx1 nCov-19 (Vaxzevria) vaccine is efficient and safe. However, in rare cases vaccinated individuals developed life-threatening thrombotic complications, including thrombosis in cerebral sinus and splanchnic veins. Monitoring of the applied vector in vivo represents an important precondition to study the molecular mechanisms underlying vaccine-driven adverse effects now referred to as vaccine-induced immune thrombotic thrombocytopenia (VITT). We previously have shown that digital PCR (dPCR) is an excellent tool to quantify transgene copies in vivo. Here, we present a highly sensitive dPCR for in situ quantification of ChAdOx1 nCoV-19 copies. Using this method, we quantified vector copies in human plasma 24, 72, and 168 h post vaccination and in a variety of murine tissues in an experimental vaccination model 30 min post injection. We describe a method for high-sensitivity quantitative detection of ChAdOx1 nCoV-19 with possible implications to elucidate the mechanisms of severe ChAdOx1 nCov-19 vaccine complications.

Enhanced Immune Reconstitution of γδ T Cells after Allogeneic Stem Cell Transplantation Overcomes the Negative Impact of Pretransplantation Minimal Residual Disease-Positive Status in Patients with Acute Myelogenous Leukemia

Minimal/measurable residual disease (MRD) before allogeneic stem cell transplantation (allo-SCT) in patients with acute myelogenous leukemia (AML) is a poor risk factor for outcome. γδ T cells represent a unique minority lymphocyte population that is preferentially located in peripheral tissues, can recognize antigens in a non-MHC-restricted manner, and plays a "bridging" role between the innate and adaptive immune systems. In this study, we investigated a potential graft-versus-leukemia effect of γδ T cell reconstitution post-transplantation in AML patients with pretransplantation positive MRD status (MRD⁺). MRD assessment was performed in 202 patients using multicolored flow cytometry ("different from normal" strategy); 100 patients were deemed MRD⁺. Analysis for absolute concentrations of CD3⁺, CD4+, CD8⁺, natural killer, and γδ T cells were performed by flow cytometry according to an internal protocol at day +30 and +100 post-transplantation. Differences between categorical and continuous variables were determined using the chi-square and Student t test, respectively. The Mann-Whitney U test was used to compare medians of continuous variables. Spearman's correlation was used for nonparametric assessment of correlation between different cell subsets during immune reconstitution. Kaplan-Meier survival analysis and Cox regression analysis were used to investigate the associations between immune reconstitution and survival outcomes. Gray's analysis was used to compute incidences of relapse, nonrelapse mortality, and graft-versus-host disease (GVHD). The median follow-up of survivors was 28 months (range 3 to 59 months). Younger age (≤58 years) of recipient and donor (<30 years), sex mismatch, use of a matched donor, cytomegalovirus reactivation, and administration of antithymocyte globulin were associated with a faster γδ T cell reconstitution. In multivariable analysis for MRD⁺ patients, a higher than median level of γδ T cells on days +30 and +100 resulted in significantly improved leukemia-free survival (hazard ratio [HR], 0.42 [P = .007] and 0.42 [P = .011], respectively) and overall survival (HR, 0.44 [P = .038] and 0.33 [P = .009], respectively). Furthermore, a higher γδ T cell level on day +30 was associated with a significantly reduced risk of relapse (HR, 0.36; P = .019). No impact of γδ T cell level on relapse at days +30 and +100 could be seen in MRD-negative patients, and no correlation with occurrence of GVHD was observed. Our data indicate that enhanced immune reconstitution of γδ T cells post-transplantation may overcome the higher relapse risk of pretransplantation MRD⁺ status in patients with AML.

A prognostic score including mutation profile and clinical features for patients with CMML undergoing stem cell transplantation

The inclusion of mutation status improved risk stratification for newly diagnosed patients with chronic myelomonocytic leukemia (CMML). Stem cell transplantation is a potentially curative treatment option, and patient selection is critical because of relevant transplant-related morbidity and mortality. We aimed to evaluate the impact of mutation status together with clinical presentations on posttransplant outcome. Our study included 240 patients with a median follow-up of 5.5 years. A significant association with worse survival was identified for the presence of mutations in ASXL1 and/or NRAS. In multivariable analysis, ASXL1- and/or NRAS-mutated genotype (hazard ratio [HR], 1.63), marrow blasts >2% (HR, 1.70), and increasing comorbidity index (continuous HR, 1.16) were independently associated with worse survival. A prognostic score (CMML transplant score) was developed, and the following points were assigned: 4 points for an ASXL1- and/or NRAS-mutated genotype or blasts >2% and 1 point each for an increase of 1 in the comorbidity index. The CMML transplant score (range, 0-20) was predictive of survival and nonrelapse mortality (P < .001 for both). Up to 5 risk groups were identified, showing 5-year survival of 81% for a score of 0 to 1, 49% for a score of 2 to 4, 43% for a score of 5 to 7, 31% for a score of 8 to 10, and 19% for a score >10. The score retained performance after validation (concordance index, 0.68) and good accuracy after calibration. Predictions were superior compared with existing scores designed for the nontransplant setting, which resulted in significant risk reclassification. This CMML transplant score, which incorporated mutation and clinical information, was prognostic in patients specifically undergoing transplantation and may facilitate personalized counseling.

Role of pre-transplant MRD level detected by flow cytometry in recipients of allogeneic stem cell transplantation with AML

OBJECTIVES AND METHODS

We analyzed the impact of pretransplant MRD level in bone marrow measured by flow cytometry using "different from normal" method on outcomes for 189 AML patients (108 males; median age, 58 (21-80) years). All patients were subdivided into negative (n = 96), "low" (0.1%-0.5%, n = 32), and "high" MRD (>0.5%, n = 61) groups.

RESULTS

In multivariate analysis, the hazard ratios for "high" and "low" MRD levels related to MRD negativity were 7.9 (95% CI 3.5-18.1, P < .001) and 5.4 (95% CI 2.1-14, P = .0058) for relapse; 2.3 (95% CI 1.3-4.1, P = .006) and 1.6 (95% CI 0.82-3.3, P = .16) for OS; and 2.8 (95% CI 1.7-4.7, P < .001) and 2.2 (95% CI 1.1-4.2, P = .02) for LFS, respectively. We found no significant impact of "low" MRD level on relapses (0.68, 95% CI 0.33-1.4, P = .30), OS (0.72, 95% CI: 0.36-1.5, P = .36) and LFS (0.79, 95% CI: 0.42-1.5, P = .46) related to "high" MRD group.

CONCLUSIONS

Presence of detectable MRD was indicative for a high relapse risk, low LFS and OS. "Low" MRD level showed no significant impact on relapse, LFS and OS related to "high" MRD group.

Clonal Evolution after Allogeneic Hematopoietic Stem Cell Transplantation: The Case of Myelofibrosis

The significance of clonal evolution in myelofibrosis (MF) relapse remains poorly understood. Here we performed panel sequencing in paired samples of 30 patients with MF who relapsed after undergoing allogeneic hematopoietic stem cell transplantation (alloSCT). We identified a median of 2 mutations (range, 0 to 12) in a median of 2 genes (range, 0 to 8) before allo-SCT, along with a median of 2 mutations (range, 0 to 12) in 2 genes (range, 0 to 6) at relapse. Additional whole-genome sequencing (n = 6) did not elucidate additional molecular changes. Taken together, our data provide further evidence, here on MF, that clonal evolution after alloSCT is limited and that instead, alloSCT selects specific (sub)clones.

Digital PCR Assays for Precise Quantification of CD19-CAR-T Cells after Treatment with Axicabtagene Ciloleucel

Treatment with axicabtagene ciloleucel (Axi-cel) CD19-CAR-T (chimeric antigen receptor T) cells has been approved for refractory/relapsed diffuse large B cell lymphoma (DLBCL) and primary mediastinal large B cell lymphoma (PMBCL). Because treatment success as well as side effects might depend on CAR-T cell expansion in vivo, we aimed at developing digital PCR (dPCR) assays for detection and quantification of CAR-T cells. To this end, we cloned and sequenced the complete cDNA of the CAR construct. We designed different combinations of primers and dual-labeled hydrolysis probes located in various CAR regions. Three combinations were successfully tested on CAR-positive and -negative cells in duplex reactions with a reference gene (REF) to concomitantly assess cell numbers. All assays demonstrated excellent specificity and reproducibility with neglectable inter-assay variations. For all three assays, almost perfect correlation between the two dPCRs (Axi-cel versus REF) was observed, and the limit of detection was one single CAR-transduced cell corresponding to a sensitivity of 0.01% for 100 ng genomic DNA. After cross-validation, we used one assay to monitor Axi-cel CAR-T numbers in patients. CAR-T expansion and contraction followed the expected kinetics with median peak value of 11.2 Axi-cel CAR-T cells/μL at 11.3 days (median). Clinically, we observed only two partial responses (PRs) in the five patients with CAR-T cell peak numbers below median, whereas four of the five patients with comparatively good expansion showed clinical responses (two complete responses [CRs] and two PRs) on day 30. In conclusion, we established a novel dPCR assay for the sensitive detection of transgenic CAR-T cells, which should be very useful in the context of Axi-cel treatment.

Allogeneic stem cell transplantation in patients with myelofibrosis harboring the MPL mutation

INTRODUCTION

Primary and post-ET/PV myelofibrosis are myeloproliferative neoplasms harboring in most cases driving mutations in JAK2, CALR or MPL, and a variable number of additional mutations in other genes. Molecular analysis represents a powerful tool to guide prognosis and clinical management. Only about 10% of patients with myelofibrosis harbor alterations in MPL gene. No data are available about the transplantation outcome in the specific MPL-mutated group.

PATIENTS

We collected the data of 18 myelofibrosis patients(primary: 14; post-ET: 4) transplanted in 4 EBMT centers (Hamburg, Paris, Essen, and Hannover) between 2005 and 2016.

RESULTS

Before the transplant, we explored the molecular profile by NGS and reported the frequency of mutations occurring in a panel of genes including JAK2, MPL, CALR, U2AF1, SRSF2, SF3B1, ASXL1, IDH1, IDH2, CBL, DNMT3A, TET2, EZH2, TP53, IKZF1, NRAS, KRAS, FLT3, SH2B3, and RUNX1. The 1-year transplant-related mortality was 16.5%, 5-years overall survival and 5-y relapse-free survival 83.5%. The only relapse occurred in a patient who harbored mutations in both ASXL1 and EZH2 genes.

CONCLUSION

These retrospective data suggest that MPL-mutated myelofibrosis patients have a favorable outcome after allogeneic transplantation with very low rate of disease relapse (5.5%) in comparison with the available historical controls regarding myelofibrosis in all.

Reduced intensity allogeneic stem cell transplantation for younger patients with myelofibrosis

Allogeneic stem cell transplantation (alloSCT) is a curative procedure for myelofibrosis. Elderly people are mainly affected, limiting the feasibility of myeloablative regimens. The introduction of reduced-intensity conditioning (RIC) made alloSCT feasible for older patients. Nevertheless, the incidence of myelofibrosis is not negligible in young patients, who are theoretically able to tolerate high-intensity therapy. Very few data are available about the efficacy of RIC-alloSCT in younger myelofibrosis patients. This study included 56 transplanted patients aged <55 years. Only 30% had a human leucocyte antigen (HLA)-matched sibling donor, the others were transplanted from a fully-matched (36%) or partially-matched (34%) unrelated donor. All transplants were conditioned according the European Society for Blood and Marrow Transplantation protocol: busulfan-fludarabine + anti-thymocyte globulin, followed by ciclosporin and mycophenolate. One patient experienced primary graft failure. Incidence of graft-versus-host disease grade II-IV was 44% (grade III/IV 23%). One-year non-relapse mortality was 7% and the 5-year cumulative incidence of relapse was 19%. After a median follow-up of 8·6 years, the estimated 5-year progression-free survival and overall survival (OS) was 68% and 82%, respectively. Patients with fully-matched donor had a 5-year OS of 92%, in contrast to 68% for those with a mismatched donor (P = 0·03). The most important outcome-determining factor is donor HLA-matching. In conclusion, RIC-alloSCT ensures optimal engraftment and low relapse rate in younger myelofibrosis patients, enabling the possibility of cure in this group.

Impact of ruxolitinib pretreatment on outcomes after allogeneic stem cell transplantation in patients with myelofibrosis

INTRODUCTION

Ruxolitinib is the first approved drug for treatment of myelofibrosis, but its impact of outcome after allogeneic stem cell transplantation (ASCT) is unknown.

PATIENTS AND METHODS

We reported on 159 myelofibrosis patients (pts) with a median age of 59 years (r: 28-74) who received reduced intensity ASCT between 2000 and 2015 in eight German centers from related (n = 23), matched (n = 86) or mismatched (n = 50) unrelated donors. Forty-six (29%) patients received ruxolitinib at any time point prior to ASCT. The median daily dose of ruxolitinib was 30 mg (range 10-40 mg) and the median duration of treatment was 4.9 months (range 0.4-39.1 months).

RESULTS

Primary graft failure was seen in 2 pts (4%) in the ruxolitinib and 3 (2%) in the non-ruxolitinib group. Engraftment and incidence of acute GVHD grade II to IV and III/IV did not differ between groups (37% vs 39% and 19% vs 28%, respectively), nor did the non-relapse mortality at 2 years (23% vs 23%). A trend for lower risk of relapse was seen in the ruxolitinib group (9% vs 17%, P = .2), resulting in a similar 2 year DFS and OS (68% vs 60% and 73% vs 70%, respectively). No difference in any outcome variable could be seen between ruxolitinib responders and those who failed or lost response to ruxolitinib.

CONCLUSIONS

These results suggest that ruxolitinib pretreatment in myelofibrosis patient does not negatively influence outcome after allogeneic stem cell transplantation.

Peritransplantation Ruxolitinib Prevents Acute Graft-versus-Host Disease in Patients with Myelofibrosis Undergoing Allogenic Stem Cell Transplantation

JAK inhibition by ruxolitinib is approved for treating myelofibrosis and also has shown efficacy in treating steroid-resistant acute and chronic graft-versus-host disease (GVHD). In 12 patients with myelofibrosis (median age, 63 years; range, 43 to 71 years) who were treated with ruxolitinib and underwent allogeneic stem cell transplantation (ASCT), ruxolitinib was continued (2 × 5 mg daily) until stable engraftment. No graft failure was observed, and leukocyte engraftment was achieved after a median of 12 days (range, 11 to 18 days). One patient developed fever of unknown origin after discontinuation of ruxolitinib; otherwise, no withdrawal syndrome was observed. Overall, only 1 patient each experienced acute GVHD grade I or II, resulting in an 8% incidence of acute GVHD grade II-IV at day +100, with no nonrelapse mortality. Complete chimerism was achieved in 11 patients after a median of 40 days, and molecular clearance of the underlying driver mutation was noted in 10 patients after a median of 32 days. Cytomegalovirus (CMV) reactivation occurred in 5 patients (41%), 1 of whom had CMV colitis as well, but all resolved after ganciclovir treatment. In 2 patients, ruxolitinib had to be discontinued on day 17 and day 18 after ASCT due to cytopenia after engraftment. Levels of inflammatory cytokines IL-8, IL-10, IL-6, TNFR2, INF-α, and INF-β were reduced after ruxolitinib treatment. After day +100, 4 patients developed acute GVHD (1 with grade I, 2 with grade II, and 1 with grade III) after tapering of cyclosporine, and all patients were alive at a median follow-up of 17 months (range, 12 to 18 months).

Impact of molecular residual disease post allografting in myelofibrosis patients

We screened 136 patients with myelofibrosis and a median age of 58 years who underwent allogeneic stem cell transplantation (AHSCT) for molecular residual disease for JAKV617F (n=101), thrombopoietin receptor gene (MPL) (n=4) or calreticulin (CALR) (n=31) mutation in peripheral blood on day +100 and +180 after AHSCT. After a median follow-up of 78 months, the 5-year estimated overall survival was 60% (95% confidence interval (CI): 50-70%) and the cumulative incidence of relapse at 5 years was 26% (95% CI: 18-34%) for the entire study population. The percentage of molecular clearance on day 100 was higher in CALR-mutated patients (92%) in comparison with MPL- (75%) and JAKV617F-mutated patients (67%). Patients with detectable mutation at day +100 or at day +180 had a significant higher risk of clinical relapse at 5 years than molecular-negative patients (62% vs 10%, P<0.001) and 70% vs 10%, P<0.001, respectively) irrespectively of the underlying mutation. In a multivariate analysis, high-risk diseases status (hazard ratio (HR) 2.5; 95% CI: 1.18-5.25, P=0.016) and detectable MRD at day 180 (HR 8.36, 95% CI: 2.76-25.30, P<0.001) were significant factors for a higher risk of relapse.

Indication of Horizontal DNA Gene Transfer by Extracellular Vesicles

The biological relevance of extracellular vesicles (EV) in intercellular communication has been well established. Thus far, proteins and RNA were described as main cargo. Here, we show that EV released from human bone marrow derived mesenchymal stromal cells (BM-hMSC) also carry high-molecular DNA in addition. Extensive EV characterization revealed this DNA mainly associated with the outer EV membrane and to a smaller degree also inside the EV. Our EV purification protocol secured that DNA is not derived from apoptotic or necrotic cells. To analyze the relevance of EV-associated DNA we lentivirally transduced Arabidopsis thaliana-DNA (A.t.-DNA) as indicator into BM-hMSC and generated EV. Using quantitative polymerase chain reaction (qPCR) techniques we detected high copy numbers of A.t.-DNA in EV. In recipient hMSC incubated with tagged EV for two weeks we identified A.t.-DNA transferred to recipient cells. Investigation of recipient cell DNA using quantitative PCR and verification of PCR-products by sequencing suggested stable integration of A.t.-DNA. In conclusion, for the first time our proof-of-principle experiments point to horizontal DNA transfer into recipient cells via EV. Based on our results we assume that eukaryotic cells are able to exchange genetic information in form of DNA extending the known cargo of EV by genomic DNA. This mechanism might be of relevance in cancer but also during cell evolution and development.

Correlation of somatic mutations with outcome after FLAMSA-busulfan sequential conditioning and allogeneic stem cell transplantation in patients with myelodysplastic syndromes

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative treatment option for myelodysplastic syndromes (MDS). Little is known about the prognostic impact of mutations, for example, in TP53 specifically after allo-HSCT. We here describe the prognostic impact of mutations in a panel of 19 genes analyzed by amplicon-based next-generation-sequencing in a uniformly treated patient cohort. Sixty-two patients with a median age of 61 yr suffered from MDS with 0-20% bone marrow blasts. International Prognostic Score was intermediate 1 (15%) and higher (79%). Conditioning uniformly was performed using a sequential approach in which FLAMSA chemotherapy was followed by Busulfan-based conditioning. Patients mostly were transplanted from an unrelated donor (77%), and 36% of patients received a graft from a mismatched donor. Median number of mutations was 2 (range 0-6). RUNX1, GATA2, TET2, and CEBPA were the genes most frequently found mutated. TP53, a factor previously reported to confer adverse prognostic impact after allogeneic stem cell transplantation, was mutated in samples from eight patients, one of which showed a silent mutation. With an estimated 5-yr overall/disease-free survival of 48 ± 7%/41 ± 7%, none of the mutations analyzed showed a prognostic impact in this analysis of the largest uniformly treated cohort thus far. This especially holds true for patients with a mutation in TP53.

Postallogeneic monitoring with molecular markers detected by pretransplant next-generation or Sanger sequencing predicts clinical relapse in patients with myelodysplastic/myeloproliferative neoplasms

Relapse is the major cause of treatment failure after allogeneic stem-cell transplantation (AHSCT) for patients with myelodysplastic syndrome/myeloproliferative syndrome neoplasms (MDS/MPN). We evaluated the impact of molecular mutations on outcome and the value of molecular monitoring post-transplantation. We screened 45 patients with chronic myelomonocytic leukemia (n = 39 patients, including seven with transformed-acute myeloid leukemia), MDS/MPN unclassifiable (n = 5), and atypical BCR-ABL1-negative CML (n = 1) for mutations in ASXL1, CBL, NRAS, and TET2 genes by molecular genetics including a sensitive next-generation sequencing (NGS) technique. In 36 patients, sufficient DNA was available for molecular analyses. In particular, TET2 and CBL mutations were screened applying amplicon deep sequencing. In 89% of cases, at least one mutation could be detected: ASXL1: n = 18 (50%); CBL: n = 7 (19%); TET2: n = 15 (42%); and NRAS: n = 11 (32%). Survival after AHSCT at 5 yr was 46% (95% CI 28-64%) and was not influenced by any mutation. After a median of 6 months after AHSCT in 33% of the patients, one of the molecular markers was still detectable, resulting in a higher incidence of relapse than in patients with undetectable mutations (50% vs. 15%, P = 0.04). In conclusion, pretransplant molecular mutation analysis can help to detect biomarkers in patients with MPN/MDS, which may be subsequently used as minimal residual disease markers after AHSCT.

Impact of high-risk cytogenetics and achievement of molecular remission on long-term freedom from disease after autologous-allogeneic tandem transplantation in patients with multiple myeloma

Within a prospective protocol, the incidence and impact of achievement of molecular remission (mCR) and high-risk cytogenetics was investigated in 73 patients with multiple myeloma (MM) after autologous (auto)-allogeneic (allo) tandem stem cell transplantation (SCT). After induction chemotherapy, patients received melphalan 200 mg/m(2) before undergoing auto-SCT, followed 3 months later by melphalan 140 mg/m(2) and fludarabine 180 mg/m(2) before allo-SCT. Sixteen patients had high-risk cytogenetic features, defined by positive FISH for del(17p13) and/or t(4;14). Overall, 66% of the patients achieved CR or near-CR, and 41% achieved mCR, which was sustained negative (at least 4 consecutive samples negative) in 15 patients (21%), with no significant difference in incidence between the patients with high-risk cytogenetics and others (P = .70). After a median follow-up of 6 years, overall 5-year progression-free survival was 29%, with no significant difference between del 17p13/t(4;14)-harboring patients and others (24% versus 30%; P = .70). The 5-year progression-free survival differed substantially according to the achieved remission: 17% for partial remission, 41% for CR, 57% for mCR, and 85% for sustained mCR. These results suggest that auto-allo tandem SCT may overcome the negative prognostic effect of del(17p13) and/or t(4;14) and that achievement of molecular remission resulted in long-term freedom from disease.

Screening and monitoring of MPL W515L mutation with real-time PCR in patients with myelofibrosis undergoing allogeneic-SCT

Monitoring of minimal residual disease (MRD) after allogeneic (allo)-SCT for myelofibrosis (MF) allows recognizing the depth of remission and thus guides application of appropriate therapeutic interventions. MPL W515L/K mutations, which are detected in 5-10% of JAK2V617F-negative patients, may be useful for this purpose. Using a highly sensitive quantitative PCR method, we tested 90 patients with MF who underwent allo-SCT for the presence of MPL W515L/K mutations. Two patients with primary MF were found to harbor MPLW515L while no patient was positive for MPLW515K mutation. Both patients were JAK2V617F negative and cleared the mutation rapidly after allo-SCT and remained negative for a median follow-up of 19 months. The results of molecular monitoring correlated well with other remission parameters such as normalization of peripheral blood counts and morphology and complete donor chimerism. We conclude that MPLW515L can be cleared after allo-SCT and hence may be used as an MRD marker in a proportion of JAK2V617F-negative MF patients.

Bone marrow mesenchymal stromal cells remain of recipient origin after allogeneic SCT and do not harbor the JAK2V617F mutation in patients with myelofibrosis

The close association of the myeloproliferative neoplasms with the activating non-receptor tyrosine kinase JAK2V617F mutation is well established. To further clarify the pathomechanisms of this mutation in patients with myelofibrosis, we performed screening with quantitative real-time PCR for the respective mutation in in vitro expanded bone marrow (BM) mesenchymal stromal cells (MSCs) and compared the results with BM/peripheral blood (PB). Eight patients with primary/secondary myelofibrosis were investigated before (n = 4) or after allogeneic stem cell transplantation (n = 4). All patients had systemic evidence of the JAK2V617F mutation in BM/PB (mutation ratios 0.2-23.5) at the time of investigation in contrast to negative results in the MSCs (n = 7) or a very low (0.004) mutation ratio (n = 1) which was probably due to hematopoietic contamination. The four patients post-transplant had systemic donor chimerism between 96.5 and 100% in BM/PB, while MSCs showed no evidence of donor-specific alleles. In conclusion, in myelofibrosis, the JAK2V617F mutation is restricted to hematopoietic cells, and cannot explain the stromal alterations being observed in this disorder. Further, the MSCs remain of recipient origin after allogeneic SCT, which might contribute to the increased risk of graft dysfunction or failure in myelofibrosis patients after allogeneic transplantation.

Post-transplant immunotherapy with donor-lymphocyte infusion and novel agents to upgrade partial into complete and molecular remission in allografted patients with multiple myeloma

OBJECTIVE

To investigate post-transplant immunotherapy with escalating donor-lymphocyte infusions (DLI) and novel agents (thalidomide, bortezomib, and lenalidomide) to target complete remission (CR).

MATERIALS AND METHODS

Thirty-two patients with multiple myeloma who achieved only partial remission after allogeneic stem cell transplantation were treated with DLI. If no CR was achieved, one of the novel agents was added to target CR.

RESULTS

CR defined either by European Group for Blood and Marrow Transplantation criteria, flow cytometry, or molecular methods as assessed by patient-specific immunoglobulin H-polymerase chain reaction or plasma cell chimerism polymerase chain reaction was accomplished in 59%, 63%, and 50% of patients, respectively. Achievement of CR resulted in improved 5-year progressive-free and overall survival, according to European Group for Blood and Marrow Transplantation criteria (53% vs 35%; p=0.03 and 90% vs 62%; p=0.06), flow cytometry (74% vs 15%; p=0.001 and 100% vs 52%; p=0.1), or molecular methods (84% vs 38%; p=0.001 and 100% vs 71%; p=0.03).

CONCLUSIONS

Our finding demonstrates the clinical relevance of posttransplantation therapies to upgrade remission, and of remission's depth for long-term survival in myeloma patients.

Monitoring of the JAK2-V617F mutation by highly sensitive quantitative real-time PCR after allogeneic stem cell transplantation in patients with myelofibrosis

The JAK2-V617F mutation occurs in about 50% of patients with myelofibrosis and might be a reliable marker to monitor residual disease after allogeneic stem cell transplantation. We describe a new, highly sensitive (>or= 0.01%) real-time polymerase chain reaction (PCR) to monitor and quantify V617F-JAK2-positive cells after dose-reduced allogeneic stem cell transplantation. After 22 allogeneic stem cell transplantation procedures in 21 JAK2-positive patients with myelofibrosis, 78% became PCR negative. In 15 of 17 patients (88%), JAK2 remained negative after a median follow-up of 20 months. JAK2 negativity was achieved after a median of 89 days after allograft (range, 19-750 days). A significant inverse correlation was seen for JAK2 positivity and donor-cell chimerism (r:-0.91, P<.001). Four of 5 patients who never achieved JAK2 negativity fulfilled during the entire follow-up all criteria for complete remission recently proposed by the International Working Group, suggesting a major role for JAK2 measurement to determine depths of remission. In one case, residual JAK2-positive cells were successfully eliminated by donor lymphocyte infusion. In conclusion, allogeneic stem cell transplantation after dose-reduced conditioning induces high rates of molecular remission in JAK2-positive patients with myelofibrosis, and quantification of V617F-JAK2 mutation by real-time PCR allows the detection of minimal residual disease to guide adoptive immunotherapy.

Kinetics of plasma-cell chimerism after allogeneic stem cell transplantation by highly sensitive real-time PCR based on sequence polymorphism and its value to quantify minimal residual disease in patients with multiple myeloma

OBJECTIVE

To investigate lineage-specific chimerism of plasma cells after allogeneic transplantation by real-time PCR based on bi-allelic sequence polymorphism or, in case of female-to-male transplantation, on the detection of the DFFRY gene and to determine its value to quantify minimal residual disease in myeloma patients.

METHODS

Forty-eight samples from bone marrow samples and peripheral blood from 34 nonmyeloma patients were analyzed at different times after transplantation. Sixty-two samples from 22 myeloma patients were analyzed at different times after allogeneic stem cell transplantation, and results were compared with immunofixation and, in some cases, with PCR data using patient-specific primers.

RESULTS

The median chimerism for T cells at day +100 was greater than 99.9% and remained stable on day +180 and 1 year after transplantation. In contrast, the median donor plasma cell chimerism at day +100 was 95.5%, at day +180 98.6%, at day +360 99.8%, and 2 or more years after transplantation greater than 99.9%. Sensitivity of real-time PCR using human short insertion/deletion polymorphisms (SIDP) was 10(-4) and in case of Y-PCR 10(-5). Sequential monitoring of donor plasma cell chimerism showed that increasing and stable chimerism were associated with ongoing remission in 15 out of 16 samples (93%), and decreases in chimerism predicted relapse in 5 out of 6 patients.

CONCLUSION

We conclude that plasma cell chimerism after allogeneic stem cell transplantation is delayed in comparison to T-cell chimerism. Sequential quantitative measurement of plasma cells after allogeneic stem cell transplantation with highly sensitive real-time PCR allows monitoring of residual host-tumor cells in patients with multiple myeloma and allows guiding adoptive immunotherapy strategies to enhance remission status and to prevent clinical relapse.

Detection of disseminated epithelial cancer cells by liquid culture--factors interfering with the standardization of assays

BACKGROUND

Immunocytochemistry is the standard method for detection of disseminated breast-cancer cells. Tumor-cell enrichment by cell culture has been used by several investigators, however assays published have not been well-standardized.

METHODS

Breast-cancer cells from two lines were diluted in hemopoietic cells of varying origins and cultured in different media and different flasks. Factors influencing successful tumor-cell amplification by liquid culture were identified by investigation of 277 cultures. Parallel clinical samples, consisting of BM aspirations, leukapheresis samples and peripheral blood samples obtained from women with breast cancer, were investigated in 113 cultures. Cancer-cell detection by cell culture could be compared to immunocytochemistry in 101 cases.

RESULTS

The frequency of tumor-cell detection was not improved by liquid culture, but a significant correlation between conventional tumor-cell detection and detection after liquid culture was found. Factors influencing tumor-cell amplification in the dilution assay could not be transferred to the investigation of clinical samples. It was concluded that culture-enrichment of disseminated cancer cells was very complex, and could be influenced by a variety of factors-even when a model system was used.

DISCUSSION

It should be recognized that culture-enriched cancer cells probably represent a highly selected population of disseminated cancer cells, despite the significant correlation between tumor cells detected by conventional methods and following conventional methods after liquid culture. There is currently no evidence to suggest that cancer-cell amplification by cell culture could become a standardized technique for the detection of disseminated epithelial tumor cells.

Interference of cytokeratin-20 and mammaglobin-reverse-transcriptase polymerase chain assays designed for the detection of disseminated cancer cells

Several reverse-transcriptase polymerase chain reaction (rtPCR) assays have been designed for the detection of disseminated cancer cells. The specificity of these discussed molecular approaches is controversial. Biological interference of the cytokeratin-20 and mammaglobin rtPCR assays has been investigated. Cell lines of different lineages and bone marrow and peripheral stem cells from patients without epithelial cancer have been examined for the transcription of the cytokeratin-20 (CK20) and mammaglobin messages prior to and after stimulation with different cytokines in a total of 370 liquid cultures. Amplification of both messages from clinical samples prior to stimulation does not support the high specificity for the detection of disseminated epithelial cancer cells as reported. Cytokeratin-20 was amplified from the chronic myeloic leukemia (CML)-derived line K562. Transcription was not influenced by cytokines, either in cell-line experiments or in clinical samples. The thesis of a low-level background transcription in granulocytes is supported. Mammaglobin was induced in cell lines significantly by GM-CSF and in clinical samples additionally by several more cytokines. These results indicate that under certain conditions involving cytokine production, the use of mammaglobin rtPCR for the detection of epithelial cancer cells could be limited. In conclusion, the mechanism of interference of both rtPCR assays are completely different and further research is necessary before the cytokeratin-20 or mammaglobin rtPCR could become standard methods for the detection of disseminated epithelial cancer cells. These factors leading to so-called false-positive results have to be considered in future applications of rtPCR for the detection of minimal residual disease.

Disseminated breast cancer cells prior to and after high-dose therapy

Women with breast cancer in a distinct stage of disease can benefit from high-dose therapy (HDT) with autologous stem cell support; however, a significant number of these patients relapse despite this intensive treatment. This study investigates the persistence of malignancy on the single-cell level. A total of 194 data sets consisting of bone marrow and blood samples obtained prior to and after HDT and of aliquots of apheresis products were searched with immunocytochemistry and reverse transcriptase polymerase chain reaction (RT-PCR) for disseminated cancer cells. Presence of cancer cells in the marrow is frequent prior to and after HDT, but HDT reduces the amount of malignant cells in marrow significantly. In contrast, there was no effect on the number of circulating cancer cells. Reinfusion of contaminated apheresis products was surprisingly associated with a low number of malignant cells in bone marrow after HDT and vice versa. The impact of disseminated tumor cells in bone marrow, apheresis, and peripheral blood on disease-free survival after HDT could be investigated in a total of 165 samples. Surprisingly, neither the presence of tumor cells in marrow or blood nor in apheresis was associated with a bad prognosis in Kaplan-Meyer survival analysis. These results suggest that apheresis products and bone marrow should be regarded as different biological compartments for epithelial cancer cells. It can be concluded that complete elimination of disseminated cancer cells by HDT is not always possible. The theory of reinduction of metastatic breast cancer by accidentally reinfused contaminants is not supported by this study so far. However, further research is necessary to identify distinct cell populations with the potentially capacity to metastasize.

Influence of Preharvest Tumor Cell Contamination in Bone Marrow or Blood Does Not Predict Resultant Tumor Cell Contamination of Granulocyte Colony-Stimulating Factor Mobilized Stem Cells

Tumor cell contamination of stem cell collections harvested from breast cancer patients is a common phenomenon described by several investigators but with findings that vary among reports. Although so-called co-mobilization of these cells has been hypothesized, the origin of tumor cell contamination in stem cells is still unknown. A total of 47 G-CSF mobilized stem cell grafts from patients with nodal-positive (n = 30), chemosensitive metastatic (n = 11), and 5 women with inflammatory breast cancer were evaluated for cancer cells by immunocytochemistry. Additionally, 40 bone marrow aspirations and 23 peripheral blood samples collected prior to apheresis and after one to two cycles of conventional chemotherapy were available for examination. Tumor cell contamination of leukapheresis correlated best with preharvest blood state. This was valid when the nominal (positive/negative) presence of tumor cells in blood was compared to the nominal presence of tumor cells in apheresis samples and when the it was correlated to the tumor cell load of apheresis samples (TCL = tumor cells per 10(6) nucleated cells investigated). The correlation between blood and stem cells was better (nominal and quantitative) than that between marrow and stem cells, despite the larger sample size of marrow aspirations. The presence or absence of cancer cells in apheresis samples could not be safely predicted by the presence or absence of tumor cells in marrow or blood alone. Diagnostic specificity seems to improve from a combination of results from marrow and blood analysis. No correlation was found in quantitative analysis of tumor cell contamination between marrow and blood. In conclusion, the results suggest that blood and bone marrow represent different compartments for epithelial cancer cells and that contaminating tumor cells in stem cell harvests may be derived from the blood and/or marrow compartment. The tumor cell contamination of a stem cell harvest cannot be safely predicted by a preceding blood or marrow analysis.

Urokinase-like plasminogen activator receptor expression on disseminated breast cancer cells

Disseminated tumor cells are detected frequently in bone marrow, peripheral blood, and cytokine-mobilized peripheral blood cell products of women undergoing high-dose therapy for breast cancer. Several attempts were made to purge autografts from contaminating cancer cells; however, the biological and clinical impact of these contaminations has not been clarified so far. Expression of distinct phenotypes is a surrogate marker for metastatic behavior of cancer cells. The expression of the urokinase-like plasminogen activator receptor seems to be a factor of high importance. It is not expressed by normal mammary tissue. Disseminated cancer cells from marrow, blood, and stem cell products have been investigated by double-stain technique for urokinase-like plasminogen activator receptor (uPA-R) expressing cytokeratin-positive cells. uPA-R(+)/CK(+) cells could be found in all qualities of samples; however, significantly less in G-CSF-mobilized peripheral blood stem cells compared to samples of other provenance (p = 0.02). It can be concluded that epithelial cells of malignant phenotype occur in blood, marrow, and autografts of breast cancer patients. Populations of disseminated tumor cells are phenotypically heterogeneous. Reduced uPA-R expression on cancer cells from leukapheresis samples might suggest a less aggressive nature of these cells compared to disseminated cells found in bone marrow. Furthermore, the data suggest that the phenotype of tumor cell contamination in leukapheresis products differs significantly from those of disseminated cancer cells in bone marrow or blood.

Immunomagnetic tumor cell selection--implications for the detection of disseminated cancer cells

BACKGROUND

The optimal method for the detection of disseminated epithelial cancer cells has not yet been found. The standard method, using immunocytochemistry, offers a sensitivity of up to 10(-6). Molecular methods such as cytokeratin-19 RT-PCR are about 10 times as sensitive, but they are hampered by interference such as illegitimate gene expression.

STUDY DESIGN AND METHODS

Immunomagnetic bead selection of epithelial cancer cells using conjugates directed against the human epithelial antigen (HEA) followed by immunocytochemistry testing was investigated in this trial.

RESULTS

No cytokeratin-positive cells could be enriched from 56 control samples. In 104 clinical samples of bone marrow aspirations, PBPC collections, and venous blood obtained from breast cancer patients, the cytokeratin-positive rate increased significantly, from 29.9 percent before selection to 54.8 percent after enrichment. Even the yield of detected cancer cells was significantly higher after selection. Up to 2.5 x 10(8) MNCs were easily processed. However, the mean cancer cell recovery after HEA enrichment was only 24.4 percent. Subsequently, selected epithelial cells were successfully immunophenotyped by use of a double-stain technique detecting cytokeratin-positive cells and the urokinase-like plasminogen activator receptor.

CONCLUSION

HEA bead selection in combination with the standard immunocytochemistry method is a powerful and specific tool for the detection of disseminated cancer cells without false-positive results. Furthermore, it delivers enough cells for subsequent investigations such as characterization studies.