Low incidence of tumor lysis syndrome in elderly patients with chronic lymphocytic leukemia treated with venetoclax under real-world conditions: results from the prospective observational VeRVe study.

Venetoclax is active in both frontline and relapsed/refractory settings for the treatment of chronic lymphocytic leukemia (CLL). Although the prevalence and severity of tumor lysis syndrome (TLS) are well characterized in clinical trials, laboratory and clinical TLS remain relatively unexplored in real-world clinical practice.In this prospective, real-world observational study, we aimed to determine the incidence and outcomes of TLS in patients with CLL receiving venetoclax outside a clinical trial. The study (VeRVe) was conducted in centers in Austria, Germany, and Switzerland.Two hundred and thirty-nine patients were treated according to local label with at least one dose of venetoclax. Patient demographics, baseline characteristics, and blood chemistry at baseline were documented, and descriptive statistical analyses were conducted.Seventy eight patients (33%) were treated with venetoclax monotherapy, 101 (42%) with venetoclax in combination with rituximab and 60 (25%) with venetoclax in combination with obinutuzumab. In all cases, the TLS risk mitigation strategy adhered to the ramp-up protocol. Median age was 73 years and 66% of patients were male. The majority of patients (75%) had relapsed/refractory CLL, 63/192 (32.8%) patients tested had a del(17p) and 93/134 (69.4%) patients tested had unmutated immunoglobulin heavy chain variable region gene (IGHV). Clinical TLS occurred in 5 patients (2.1%) and laboratory TLS occurred in 15 patients (6.3%). Ten patients received specific treatment, of which 6 were hospitalized. There were no deaths due to a TLS event and venetoclax was well-tolerated. Of the 5 clinical TLS events reported, none were fatal or resulted in renal failure (NCT03342144, registered on Nov 10, 2017).

Final Results from RIBBIT: A Randomized Phase III Study to Evaluate Efficacy and Quality of Life in Patients with Metastatic Hormone Receptor-Positive, HER2-Negative Breast Cancer Receiving Ribociclib in Combination with Endocrine Therapy or Chemotherapy with or without Bevacizumab in the First-Line Setting.

Background: We investigated the efficacy and health-related quality of life (HRQoL) in patients receiving either ribociclib plus endocrine therapy (ET) or chemotherapy with/without bevacizumab as first-line treatment of metastatic hormone receptor (HR)-positive, HER2-negative breast cancer (BC). Patients and Methods: In this randomized, phase III study (RIBBIT), 38 patients diagnosed with metastatic HR-positive, HER2-negative BC with presence of visceral metastases recruited between May 2018 and December 2020 were randomly assigned in a 1:1 ratio to either arm A (ribociclib + ET) or arm B (chemotherapy with/without bevacizumab) at 12 sites in Germany. The primary endpoint was progression-free survival (PFS). Secondary endpoints included overall response rate (ORR), overall survival (OS), patient-reported HRQoL, and frequency and type of adverse events. During study conduction, the recruitment rate was persistently and considerably lower than originally expected. Therefore, the recruitment was ended prematurely. The study was initially designed to enroll and randomize 158 patients. Results: Median [95% CI] PFS was 27.3 months [19.1 - NA, parameter not estimable] in arm A and 15.8 months [8.2 - NA] in arm B. Complete responses were achieved only in arm A (n = 2, 10.5%). The ORR [95% CI] between arm A (57.9% [33.5-79.7]) and arm B (52.6% [28.9-75.6]) was comparable. Median OS [95% CI] was not reached in arm A, while in arm B median OS was 28.4 months [25.0 - NA]. Patients in arm A reported less burden by side-effects. No new safety signals emerged. Conclusion: Treatment of patients with visceral metastatic HR-positive, HER2-negative BC with ribociclib in combination with ET showed a tendency toward a more favorable clinical outcome. Despite small numbers of patients and sites, this head-to-head comparison with chemotherapy supports the use of ribociclib with ET in patients with visceral metastasis at risk of fast disease progression.

Neratinib as Extended Adjuvant Treatment of HER2-Positive/HR-Positive Early Breast Cancer Patients in Germany, Austria, and Switzerland: Interim Results of the Prospective, Observational ELEANOR Study.

Introduction: Prognosis of patients diagnosed with HER2+ early breast cancer (eBC) has substantially improved, but distant recurrences impacting quality of life and survival still occur. One treatment option for extended adjuvant treatment of patients with HER2+/HR+ eBC is neratinib, available in Europe for patients who completed adjuvant trastuzumab-based therapy within 1 year. The ELEANOR study is investigating the real-world use of neratinib in Germany, Austria, and Switzerland. Results from an interim analysis of the first 200 patients observed for ≥3 months are reported. Methods: The primary objective of this prospective, multicenter, observational study is to assess patient adherence to neratinib (defined as the percentage of patients taking neratinib on ≥75% prescribed days). Secondary objectives are patient characteristics and treatment outcomes. Results: At cut-off (May 2, 2022), a total of 202 patients had been observed for ≥3 months, with neratinib treatment documented for 187 patients (median age: 53.0 years; 67.9% at increased risk of disease recurrence). In total, 151 (80.7%) patients had received prior neoadjuvant treatment; of these, 82 (54.3%) patients achieved a pathologically complete response. Neratinib was initiated at a median 3.6 months after trastuzumab-based treatment, with 36.4% starting at a dose <240 mg/day. Treatment is ongoing for 46.0% of patients, with median treatment duration of 11.2 (interquartile range 0.9-12.0) months. Diarrhea was the most common adverse event (78.6% any grade, 20.3% grade ≥3); pharmacologic prophylaxis was used in 85.6% of patients. Conclusions: The pattern of anti-HER2 pretreatment observed reflected the current treatment for HER2+/HR+ eBC in Germany, Austria, and Switzerland. These interim results suggest that neratinib as an extended adjuvant is a feasible option after various anti-HER2 pretreatments and that its tolerability can be managed and improved with proactive diarrhea management.

The INFINITY study protocol: a retrospective cohort study on decision making and clinical impact of biomarker-driven precision oncology in routine clinical practice.

BACKGROUND: Precision oncology, defined as treatment of patients with targeted therapies matched to specific molecular alterations, has entered routine clinical practice. Particularly in patients with advanced cancer or hematologic malignancies, for whom no further standard therapies are available, this approach is increasingly applied as last resort option outside of the approved indication. However, data on patient outcomes are not systematically collected, analyzed, reported, and shared. We have initiated the INFINITY registry to provide evidence from routine clinical practice to fill this knowledge gap. METHODS: INFINITY is a retrospective, non-interventional cohort study conducted at approximately 100 sites in Germany (office-based oncologists/hematologists and hospitals). We aim to include 500 patients with advanced solid tumors or hematologic malignancies who received a non-standard targeted therapy based on potentially actionable molecular alterations or biomarkers. INFINITY aims to provide insights into the use of precision oncology in routine clinical practice within Germany. We systematically collect details on patient and disease characteristics, molecular testing, clinical decision-making, treatment, and outcome. DISCUSSION: INFINITY will provide evidence on the current biomarker landscape driving treatment decisions in routine clinical care. It will also provide insights on effectiveness of precision oncology approaches in general, and of specific drug class/alteration matches used outside their approved indications. TRIAL REGISTRATION: The study is registered at ClinicalTrials.gov, NCT04389541.

PRECYCLE: multicenter, randomized phase IV intergroup trial to evaluate the impact of eHealth-based patient-reported outcome (PRO) assessment on quality of life in patients with hormone receptor positive, HER2 negative locally advanced or metastatic breast cancer treated with palbociclib and an aromatase inhibitor or palbociclib and fulvestrant.

BACKGROUND: Efficacy and quality of life (QoL) are key criteria for therapy selection in metastatic breast cancer (MBC). In hormone receptor positive (HR +) human epidermal growth factor receptor 2 negative (HER2 -) MBC, addition of targeted oral agents such as everolimus or a cycline-dependent kinase 4/6 (CDK 4/6) inhibitor (e.g., palbociclib, ribociclib, abemaciclib) to endocrine therapy substantially prolongs progression-free survival and in the case of a CDK 4/6i also overall survival. However, the prerequisite is adherence to therapy over the entire course of treatment. However, particularly with new oral drugs, adherence presents a challenge to disease management. In this context, factors influencing adherence include maintaining patients' satisfaction and early detection/management of side effects. New strategies for continuous support of oncological patients are needed. An eHealth-based platform can help to support therapy management and physician-patient interaction. METHODS: PreCycle is a multicenter, randomized, phase IV trial in HR + HER2 - MBC. All patients (n = 960) receive the CDK 4/6 inhibitor palbociclib either in first (62.5%) or later line (37.5%) together with endocrine therapy (AI, fulvestrant) according to national guidelines. PreCycle evaluates and compares the time to deterioration (TTD) of QoL in patients supported by eHealth systems with substantially different functionality: CANKADO active vs. inform. CANKADO active is the fully functional CANKADO-based eHealth treatment support system. CANKADO inform is a CANKADO-based eHealth service with a personal login, documentation of daily drug intake, but no further functions. To evaluate QoL, the FACT-B questionnaire is completed at every visit. As little is known about relationships between behavior (e.g., adherence), genetic background, and drug efficacy, the trial includes both patient-reported outcome and biomarker screening for discovery of forecast models for adherence, symptoms, QoL, progression free survival (PFS), and overall survival (OS). DISCUSSION: The primary objective of PreCycle is to test the hypothesis of superiority for time to deterioration (TTD) in terms of DQoL = "Deterioration of quality of life" (FACT-G scale) in patients supported by an eHealth therapy management system (CANKADO active) versus in patients merely receiving eHealth-based information (CANKADO inform). EudraCT Number: 2016-004191-22.

Dual HER2 blockade with pertuzumab (P) and trastuzumab (T) in patients with HER2-positive metastatic breast cancer (mBC) relapsing after adjuvant treatment with T: results from a German non-interventional study (NIS) HELENA (NCT01777958).

PURPOSE: NIS HELENA documented outcomes in clinical routine practice of first-line therapy with P plus T and docetaxel (D) of patients with advanced HER2-positive BC and prior (neo)adjuvant T. METHODS: Between 06/2013 through 07/2016, 126 patients (in-label use of P at study start = full analysis set, FAS) in 81 German study sites were included. Intense documentation period was limited to 28 treatment cycles. Maximum follow-up (FU) was 24 months (mos). Safety was assessed in the safety set (SAF = eligible patients with at least one dose of P, n = 132). Median progression-free survival (PFS) was the main parameter of interest. RESULTS: Mean age of FAS patients was 55.1 [30.7-80.2] years, 81.7% (95.2%) were < 65 (75) years of age. 51.6% of the FAS patients were hormone receptor-positive (HR+), 91.3% had distant, 73.0% visceral, and 18.3% non-visceral metastases. Median disease-free interval was 40.2 [6.6-95.9] mos. Effectiveness (FAS): Median PFS was 18.8 [15.1; 24.2] mos. Overall response rate was 64.3% (55.6; 72.1). Median overall survival was 55.9 mos [41.2, not reached]. Safety (SAF): 93.9% of patients had an adverse event (AE), 32.6% a serious AE (SAE). AEs related to P occurred in 53.8% of SAF, SAEs related to P in 13.6%. Diarrhea was the most frequently reported related (S)AE. There were 8 (6.1%) patients with a fatal AE. CONCLUSION: Based on the outcomes from NIS HELENA, results of dual blockade with P+T in patients relapsing after (neo)adjuvant T as reported from the CLEOPATRA study (NCT01777958) can be transferred to routine clinical practice. No new safety signals were detected.

Improving Chemotherapy-Induced Peripheral Neuropathy in Patients with Breast or Colon Cancer after End of (Neo)adjuvant Therapy: Results from the Observational Study STEFANO.

INTRODUCTION: Chemotherapy-induced peripheral neuropathy (CIPN) is a common side effect persisting after completion of neurotoxic chemotherapies. This observational study was designed to evaluate the effectiveness of the dietary supplement OnLife® (patented mixture of specific fatty acids and palmitoylethanolamide) in improving symptoms of CIPN in breast and colon cancer patients. METHODS: Improvement of CIPN was evaluated in adult patients, previously treated with (neo)adjuvant paclitaxel- (breast cancer) or oxaliplatin-based (colon cancer) therapies, receiving OnLife® for 3 months after completion of chemotherapy. The primary endpoint was to compare the severity of peripheral sensory neuropathy (PSN) and peripheral motor neuropathy (PMN) before and at the end of OnLife® treatment. Secondary endpoints included the assessment of patient-reported quality of life and CIPN symptoms as assessed by questionnaires. RESULTS: 146 patients (n = 75 breast cancer patients and n = 71 colon cancer patients) qualified for analysis; 31.1% and 37.5% of breast cancer patients had an improvement of PSN and PMN, respectively. In colon cancer patients, PSN and PMN improved in 16.9% and 20.0% of patients, respectively. According to patient-reported outcomes, 45.9% and 37.5% of patients with paclitaxel-induced PSN and PMN, and 23.9% and 22.0% of patients with oxaliplatin-induced PSN and PMN experienced a reduction of CIPN symptoms, respectively. CONCLUSION: OnLife® treatment confirmed to be beneficial in reducing CIPN severity and in limiting the progression of neuropathy, more markedly in paclitaxel-treated patients and also in patients with oxaliplatin-induced CIPN.

Fulvestrant Plus Vistusertib vs Fulvestrant Plus Everolimus vs Fulvestrant Alone for Women With Hormone Receptor-Positive Metastatic Breast Cancer: The MANTA Phase 2 Randomized Clinical Trial.

IMPORTANCE: Randomized clinical trials have demonstrated a substantial benefit of adding everolimus to endocrine therapy. Everolimus inhibits the mammalian target of rapamycin complex 1 (mTORC1) complex but not mTORC2, which can set off an activating feedback loop via mTORC2. Vistusertib, a dual inhibitor of mTORC1 and mTORC2, has demonstrated broad activity in preclinical breast cancer models, showing superior activity to everolimus. OBJECTIVE: To evaluate the safety and efficacy of vistusertib in combination with fulvestrant compared with fulvestrant alone or fulvestrant plus everolimus in postmenopausal women with estrogen receptor-positive advanced or metastatic breast cancer. DESIGN, SETTING, AND PARTICIPANTS: The MANTA trial is an open-label, phase 2 randomized clinical trial in which 333 patients with estrogen receptor-positive breast cancer progressing after prior aromatase inhibitor treatment underwent randomization (2:3:3:2) between April 1, 2014, and October 24, 2016, at 88 sites in 9 countries: 67 patients were assigned to receive fulvestrant, 103 fulvestrant plus vistusertib daily, 98 fulvestrant plus vistusertib intermittently, and 65 fulvestrant plus everolimus. Treatment was continued until disease progression, development of unacceptable toxic effects, or withdrawal of consent. Analysis was performed on an intention-to-treat basis. INTERVENTIONS: Fulvestrant alone or in combination with vistusertib (continuous or intermittent dosing schedules) or everolimus. MAIN OUTCOMES AND MEASURES: The primary end point was progression-free survival (PFS). RESULTS: Among the 333 women in the study (median age, 63 years [range, 56-70 years]), median PFS was 5.4 months (95% CI, 3.5-9.2 months) with fulvestrant, 7.6 months (95% CI, 5.9-9.4 months) with fulvestrant plus daily vistusertib, 8.0 months (95% CI, 5.6-9.9 months) with fulvestrant plus intermittent vistusertib, and 12.3 months (95% CI, 7.7-15.7 months) with fulvestrant plus everolimus. There was no significant difference in PFS between those receiving fulvestrant plus daily or intermittent vistusertib and fulvestrant alone (hazard ratio, 0.88 [95% CI, 0.63-1.24]; P = .46; and hazard ratio, 0.79 [95% CI, 0.55-1.12]; P = .16). CONCLUSIONS AND RELEVANCE: The combination of fulvestrant plus everolimus demonstrated significantly longer PFS compared with fulvestrant plus vistusertib or fulvestrant alone. The trial failed to demonstrate a benefit of adding the dual mTORC1 and mTORC2 inhibitor vistusertib to fulvestrant. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02216786 and EudraCT number: 2013-002403-34.

Prophylaxis of chemotherapy-induced neutropenia and febrile neutropenia with lipegfilgrastim in 2489 cancer patients: final results from the non-interventional study NADIR.

Objectives: The non-interventional study (NIS) NADIR (DRKS00005711) evaluated the effectiveness and safety of prophylaxis with lipegfilgrastim, a glycopegylated granulocyte-colony stimulating factor, in 2500 patients undergoing chemotherapy in routine clinical practice. Primary objective was the incidence of chemotherapy-induced severe neutropenia, febrile neutropenia (FN), and neutropenia-associated complications. Methods: NADIR was a prospective NIS conducted in 201 study centers in Germany. Results: The analysis included 2489 patients. Main tumor types were breast cancer (n = 1198, 48.1%), lung cancer (n = 303, 12.2%), non-Hodgkin lymphoma (NHL; n = 337, 13.5%), and prostate cancer (n = 111, 4.5%). Nine hundred and ten (36.6%) patients were aged ≥65 years (regarded as "elderly" patients). Severe neutropenia (CTCAE grade 3/4) was reported in 26.8% (n = 666) and 25.2% (n = 229) of the total population and elderly patients, respectively. FN was documented in 2.7% (n = 68) of the total population vs 3.0% (n = 27) of elderly patients. Primary prophylaxis with lipegfilgrastim among patients with high risk of FN (>20%) was documented in 83.5% of the total population and 75.1% of elderly patients. Infections (CTCAE grade 3/4) were documented in 99 patients (4.0%) in the total population vs 47 (5.1%) elderly patients. Fatal infections were reported in 14 (0.6%) patients in the total population vs 11 (1.2%) elderly patients. Overall, most frequent lipegfilgrastim-related adverse events (AEs) included bone pain (8.0%), anemia (3.2%), leucocytosis (2.7%), and thrombocytopenia (2.5%). Of the patients, 18.0% had ≥1 documented serious AE; none of the fatal events (2.7%) was lipegfilgrastim-related. Conclusions: Lipegfilgrastim administered to patients with solid tumor/NHL undergoing chemotherapy in routine clinical practice showed similar effectiveness and safety compared to the pivotal trials.

Impact of performance status and transfusion dependency on outcome of patients with myelodysplastic syndrome, acute myeloid leukemia and chronic myelomonocytic leukemia treated with azacitidine (PIAZA study).

OBJECTIVE: Azacitidine (Vidaza® ) is the standard treatment for patients with higher-risk myelodysplastic syndromes (MDS) not eligible for allogeneic stem cell transplantation. In the noninterventional study PIAZA, we evaluated the effectiveness and safety of azacitidine treatment in 149 patients with higher-risk MDS, chronic myelomonocytic leukemia (CMML) and acute myeloid leukemia (AML) in routine clinical practice. METHOD: Patients were treated according to physician's discretion. Besides evaluation of safety and effectiveness, impact of covariates on progression-free survival (PFS) was assessed. RESULTS: Median age of patients was 75 years. 61.1% of patients were diagnosed with MDS, 31.5% with AML and 7.4% with CMML. Patients were treated with azacitidine for a median of seven cycles. Median PFS was 10.9 months. Median OS was 14.1 months. Two-year survival rate was 28.9%. 45.9% of patients showed CR or PR. Stable and progressive disease were observed in 37.2% and 8% of patients, respectively. Transfusion independence was reported in 64 of 89 patients. Eastern cooperative oncology group (ECOG) performance status (PS) and red blood cell (RBC) transfusion before azacitidine therapy were identified as predictive factors for PFS. CONCLUSION: In conclusion, we estimated the duration of PFS in a real-world setting and identified ECOG PS and RBC transfusion as predictive factors for PFS. The safety of azacitidine showed a similar profile as demonstrated in the pivotal clinical trials.

NADIR: A Non-Interventional Study on the Prophylaxis of Chemotherapy-Induced Neutropenia Using Lipegfilgrastim - First Interim Analysis.

BACKGROUND: The non-interventional study (NIS) NADIR was designed to assess the effectiveness and safety of lipegfilgrastim, a novel glycopegylated granulocyte-colony stimulating factor, in reducing the risk of both febrile and severe neutropenia. METHODS: Here, the interim analysis of NIS Nadir performed under real-world conditions at 80 oncology practices across Germany is reported. For a patient to be included, lipegfilgrastim at a subcutaneous single dose of 6 mg had to be administered during at least 1 cycle of the chemotherapy under consideration. RESULTS: The interim analysis included 224 patients. Median patient age was 61.1 years (interquartile range 51.2-70.2 years). Main tumor type was breast cancer followed by lung cancer, and non-Hodgkin's lymphoma (46.0, 13.4, and 10.7%, respectively). When lipegfilgrastim was given as primary prophylaxis, no patient developed febrile neutropenia (FN). 1.3% of patients developed FN when primary prophylaxis was withheld. Only 68.6% of patients undergoing chemotherapy and at high risk (> 20%) of developing FN were treated with lipegfilgrastim during the first cycle, exposing disparity between real-world practices and current treatment guidelines. Lipegfilgrastim was well tolerated. The only grade 3/4 treatment-related adverse event was anemia in 1 patient. CONCLUSION: Lipegfilgrastim was effective and safe when administered for the prevention of chemotherapy-induced neutropenia under real-world conditions.

Quality of life under capecitabine (Xeloda®) in patients with metastatic breast cancer: data from a german non-interventional surveillance study.

AIM: This non-interventional surveillance study (NIS) collected data on the quality of life (QoL) of patients treated with capecitabine as mono- or combination chemotherapy in an outpatient setting. METHODS: Capecitabine was administered orally for 14 days of each 21-day cycle. The main parameters of interest were QoL, compliance, patient and physician satisfaction, handling of hand-foot syndrome (HFS), and efficacy. The statistics were descriptive; some differences were compared using confidence intervals (CIs). RESULTS: 735 patients from 161 centers received at least 1 dose of capecitabine. The median duration of observation was 5.5 months overall. The QoL global score was 53% (mean from the entire study population at all times), without any correlation to HFS. The overall response rate (ORR) was 35.1%, and the disease control rate (DCR) 64.4%. The median progression-free survival (PFS) was overall 6.81 months (95% CI 6.32-7.63 months) and it was significantly higher in patients with HFS (8.4 months, 95% CI 7.5-9.2 months, hazard ratio (HR) 0.60; p < 0.0001). The safety and tolerability of capecitabine were considered acceptable. The HFS incidence (all grades) was 27.1%. CONCLUSIONS: Capecitabine had a favorable risk-benefit relation in outpatient therapy. The QoL remained stable over the course of the investigation, indicating good compliance. HFS was a strong predictor of longer PFS and had no negative impact on the global QoL.

Long-term disease stabilization in a patient with castration-resistant metastatic prostate cancer by the addition of lenalidomide to low-dose dexamethasone and celecoxib.

BACKGROUND: Treatment of castration-resistant prostate cancer (CRPC) remains a challenge considering that most patients are elderly men with significant comorbidities. Alternative treatment strategies to cytotoxic therapy should be explored. There is evidence that the continuous administration of cyclooxygenase 2 (COX2) inhibitors and the immunomodulatory agents thalidomide or lenalidomide can result in longterm disease stabilization. CASE REPORT: A 70-year-old patient with castration-resistant metastatic prostate cancer was treated with a combination of low-dose dexamethasone, celecoxib and subsequently lenalidomide. The patient had longterm disease stabilization for 33 months and a very good performance status despite moderate side effects, i.e. moderate Cushing's syndrome and mild laboratory hematologic toxicity. CONCLUSION: The addition of lenalidomide to low-dose dexamethasone and celecoxib resulted in an impressive longterm disease stabilization of CRPC in this patient, allowing him to lead an active life with a good quality of life.

Differentiation of hematopoietic progenitor cells towards the myeloid and B-lymphoid lineage by hepatocyte growth factor (HGF) and thrombopoietin (TPO) together with early acting cytokines.

OBJECTIVES: The effect of stem cell factor (SCF), flt3-ligand (FL), and interleukin (IL)-3 (SF3) in combination with hepatocyte growth factor (HGF), thrombopoietin (TPO), and Hyper-IL-6 on maintenance and differentiation of early human peripheral blood-derived progenitor cells was investigated. METHODS: Single sorted CD34(+) 38(-) cells were cultured with various combinations of these growth factors in order to identify the most effective cytokine combination. Then, lineage-depleted cells were stimulated for 7 d in bulk culture before they were assessed by flow cytometry and in functional assays. RESULTS: The highest number of clones in the single-cell assay was obtained after culture with SF3 + TPO + HGF. Cell expansion with SF3 + TPO + HGF yielded an increase of the total cell number (11-fold), the number of CD34(+) cells (sevenfold), colony forming cells (CFC; 13-fold), granulocytes (CD15/66b(+); 45-fold) and B-cells (CD19/20(+); 55-fold). However, the number of long-term culture initiating cells (LTC-IC) decreased from 779 +/- 338 per 1 x 10(5) CD34(+) cells on day 0 to 253 +/- 115 on day 7. In parallel, the number of pluripotent mouse repopulating cells decreased by the factor 11, and no significant change in the proportion of human myeloid or lymphoid cells found in the mouse bone marrow was noted. CONCLUSION: The observation that mature cells of different lineages are generated and that transplantable multipotent hematopoietic cells are lost during culture suggests the differentiation of early hematopoietic progenitors toward lineage committed cells by the tested cytokines. The detection of cells expressing B-lymphoid markers after culture indicates a possible role in the propagation of B-cells.

Expression and function of homing-essential molecules and enhanced in vivo homing ability of human peripheral blood-derived hematopoietic progenitor cells after stimulation with stem cell factor.

Hematopoietic stem cell (HSC) homing from blood to bone marrow is a multistep process involving rolling, extravasation, migration, and finally adhesion in the correct microenvironment. With view to the hematopoietic recovery after clinical stem cell transplantation, we investigated the effect of stem cell factor (SCF) on the expression and the adhesive function of the alpha4beta1 and alpha5beta1 integrins very-late antigen (VLA)-4 and VLA-5 on peripheral blood-derived hematopoietic progenitor cells. After SCF stimulation, the expression of VLA-4 and VLA-5 on CD34+/c-kit+ cells obtained from healthy donors increased from 54% to 90% and from 3% to 82%, respectively. For patient-derived cells, the increase was 67% to 90% and 12% to 46%. The proportion of mononuclear cells adhering to the fibronectin fragment CH296 increased by stimulation with SCF from 14% to 23%. Accordingly, functional studies showed an approximate 30% increase of adherent long-term culture-initiating cell. The improvement of the homing abilities of SCF-stimulated HSC was confirmed by transplantation into sublethally irradiated nonobese diabetic-scid/scid mice. Six weeks after the transplantation, in eight of eight animals receiving human HSC with the addition of SCF, a profound multilineage hematopoietic engraftment was detected, whereas in the control group receiving only HSC, none of eight animals engrafted. Our data provide the first in vivo evidence that stimulation with cytokines improves the homing ability of transplanted human hematopoietic progenitor cells.

CD84 expression on human hematopoietic progenitor cells.

OBJECTIVE: CD84 is a member of the CD2 subgroup of the immunoglobulin receptor superfamily. Members of this family have been implicated in the activation of T cells and NK cells. Expression of CD84 was originally described on most mononuclear blood cells as well as platelets. To elucidate its presence on other blood cell types, we analyzed the expression pattern of CD84 on human immature CD34+ and mature hematopoietic cells. METHODS: Expression analysis was carried out by flow cytometry. The differentiation potential of CD84+ progenitor cells was assessed by colony-forming assays and long-term cultures. RT-PCR was used to analyze CD84 mRNA isoforms. RESULTS: In addition to monocytes, macrophages, B cells, and some T cells, CD84 is expressed on the cell surface of the majority of granulocytes. In addition, 64%+/-5% of CD34+ progenitor cells isolated from peripheral blood and 30.5%+/-5% from bone marrow of healthy volunteers also express CD84. The majority of CD34+ cells coexpressing lineage antigens were CD84+. In methylcellulose CD34+CD84+ cells formed primarily erythroid colonies, whereas myeloid or mixed colonies were scarce. The frequency of long-term culture-initiating cells in peripheral blood was approximately fivefold higher in CD34+CD84- vs CD34+CD84+ cells. In short-term cultures, 95% of the initially CD34+CD84- cells became CD84+ after 72 hours. CONCLUSIONS: CD84 is expressed on cells from almost all hematopoietic lineages and on CD34+ hematopoietic progenitor cells. The proliferative potential of CD34+ cells decreases with increasing CD84 expression, suggesting that CD84 serves as a marker for committed hematopoietic progenitor cells.