Daratumumab, Bortezomib, Lenalidomide, and Dexamethasone for Multiple Myeloma.

BACKGROUND: Daratumumab, a monoclonal antibody targeting CD38, has been approved for use with standard myeloma regimens. An evaluation of subcutaneous daratumumab combined with bortezomib, lenalidomide, and dexamethasone (VRd) for the treatment of transplantation-eligible patients with newly diagnosed multiple myeloma is needed. METHODS: In this phase 3 trial, we randomly assigned 709 transplantation-eligible patients with newly diagnosed multiple myeloma to receive either subcutaneous daratumumab combined with VRd induction and consolidation therapy and with lenalidomide maintenance therapy (D-VRd group) or VRd induction and consolidation therapy and lenalidomide maintenance therapy alone (VRd group). The primary end point was progression-free survival. Key secondary end points were a complete response or better and minimal residual disease (MRD)-negative status. RESULTS: At a median follow-up of 47.5 months, the risk of disease progression or death in the D-VRd group was lower than the risk in the VRd group. The estimated percentage of patients with progression-free survival at 48 months was 84.3% in the D-VRd group and 67.7% in the VRd group (hazard ratio for disease progression or death, 0.42; 95% confidence interval, 0.30 to 0.59; P<0.001); the P value crossed the prespecified stopping boundary (P = 0.0126). The percentage of patients with a complete response or better was higher in the D-VRd group than in the VRd group (87.9% vs. 70.1%, P<0.001), as was the percentage of patients with MRD-negative status (75.2% vs. 47.5%, P<0.001). Death occurred in 34 patients in the D-VRd group and 44 patients in the VRd group. Grade 3 or 4 adverse events occurred in most patients in both groups; the most common were neutropenia (62.1% with D-VRd and 51.0% with VRd) and thrombocytopenia (29.1% and 17.3%, respectively). Serious adverse events occurred in 57.0% of the patients in the D-VRd group and 49.3% of those in the VRd group. CONCLUSIONS: The addition of subcutaneous daratumumab to VRd induction and consolidation therapy and to lenalidomide maintenance therapy conferred a significant benefit with respect to progression-free survival among transplantation-eligible patients with newly diagnosed multiple myeloma. (Funded by the European Myeloma Network in collaboration with Janssen Research and Development; PERSEUS ClinicalTrials.gov number, NCT03710603; EudraCT number, 2018-002992-16.).

Prognostic Significance of the Myelodysplastic Syndrome-Specific Comorbidity Index (MDS-CI) in Patients with Myelofibrosis: A Retrospective Study.

In myelofibrosis, comorbidities (CMs) add prognostic information independently from the Dynamic International Prognostic Scoring System (DIPSS). The Myelodysplastic Syndrome-Specific Comorbidity Index (MDS-CI) offers a simple tool for CM assessment as it is calculable after having performed a careful history and physical examination, a small routine chemistry panel (including creatinine and liver enzymes) and a limited set of functional diagnostics. To assess the prognostic impact of the MDS-CI in addition to the DIPSS and the Mutation-Enhanced International Prognostic Scoring System (MIPSS)-70, we performed a retrospective chart review of 70 MF patients who had not received allogeneic stem cell transplantation (primary MF, n = 51; secondary MF, n = 19; median follow-up, 40 months) diagnosed at our institution between 2000 and 2020. Cardiac diseases (23/70) and solid tumors (12/70) were the most common CMs observed at MF diagnosis. Overall survival (OS) was significantly influenced by the MDS-CI (median OS MDS-CI low (n = 38): 101 months; MDS-CI intermediate (n = 25): 50 months; and high (n = 7): 8 months; p < 0.001). The MDS-CI added prognostic information after inclusion as a categorical variable in a multivariate model together with the dichotomized DIPSS or the dichotomized MIPSS70: MDS-CI high HR 14.64 (95% CI 4.42; 48.48), p = 0.0002, and MDS-CI intermediate HR 1.97 (95% CI 0.96; 4.03), p = 0.065, and MDS-CI high HR 19.65 (95% CI 4.71; 81.95), p < 0.001, and MDS-CI intermediate HR 1.063 (95% CI 0.65; 4.06), p = 0.2961, respectively. The analysis of our small and retrospective MF cohort suggests that the MDS-CI represents a useful tool to identify MF patients with an increased vulnerability due to comorbidities. However, analyses of larger cohorts are necessary to define the value of the MDS-CI as a prognostic tool in comparison with other comorbidity indices.

The Absolute Monocyte Count at Diagnosis Affects Prognosis in Myelodysplastic Syndromes Independently of the IPSS-R Risk Score.

The absolute monocyte count (AMC) is associated with mortality in a variety of medical conditions. Its prognostic impact in myelodysplastic syndromes (MDSs) is less well studied. Therefore, we investigated its potential prognostic value in a cohort from the Düsseldorf MDS registry in relationship to the revised international prognostic scoring system (IPSS-R). An AMC below the population's median (<0.2 × 109/L) was associated with several adverse disease features such as lower haemoglobin levels, lower count of neutrophils and platelets, and a higher percentage of blasts in the bone marrow. MDS patients with an AMC < 0.2 × 109/L had a significantly higher risk of progression into acute myeloid leukemia (AML). In a univariate, proportional hazards model the effect of the AMC as a continuous variable was modelled via p-splines. We found a U-shaped effect with the lowest hazard around 0.3 × 109/L. Accordingly, an AMC within the last quartile of the population (0.4 × 109/L) was associated with a reduced overall survival independently of IPSS-R, but not with the risk of secondary AML. Considering monocytopenia as a risk factor for AML progression in MDS may provide an additional argument for allogeneic transplantation or the use of hypomethylating agents in patients who are not clear candidates for those treatments according to current prognostic scoring systems and/or recommendations. Further studies are needed to assess the prognostic impact of the AMC in the context of prognostic scoring systems, considering the molecular risk profile, and to identify the mechanisms responsible for the higher mortality in MDS patients with a subtle monocytosis.

Humoral and cellular BNT162b2 mRNA-based booster vaccine-induced immunity in patients with multiple myeloma and persistence of neutralising antibodies: results of a prospective single-centre cohort study.

BACKGROUND: Currently available messenger ribonucleic acid (mRNA)-based vaccines against coronavirus disease (COVID-19) have been shown to be effective even in highly immunocompromised hosts, including patients with multiple myeloma. However, vaccination failure can be observed in all patient groups. METHODS: This prospective study longitudinally assessed the humoral and cellular responses to a third booster dose of BNT162b2 mRNA-based vaccine in patients with myeloma (n = 59) and healthy controls (n = 22) by measuring the levels of anti-spike (S) antibodies (electro-chemiluminescence immunoassay) including neutralising antibodies and specific T-cells (enzyme-linked immunospot assay) following booster administration. RESULTS: The third booster dose showed a high immunogenicity on the serological level among the patients with multiple myeloma (median anti-S level = 41 binding antibody units [BAUs]/ml pre-booster vs 3902 BAU/ml post-booster, p <0.001; increase in the median neutralising antibody level from 19.8% to 97%, p <0.0001). Four of five (80%) patients with a complete lack of any serological response (anti-S immunoglobulin level <0.8 BAU/ml) after two vaccine doses developed detectable anti-S antibodies after booster vaccination (median anti-S level = 88 BAU/ml post-booster). T-cell responses were largely preserved among the patients with multiple myeloma with no difference from the healthy controls following baseline vaccination (median spot-forming units [SFU]/106 of peripheral blood mononuclear cells = 193 vs 175, p = 0.711); these responses were augmented significantly after booster administration among the patients with multiple myeloma (median SFU/106 of peripheral blood mononuclear cells = 235 vs 443, p <0.001). However, the vaccination responses remained highly heterogeneous and diminished over time, with insufficient serological responses occurring even after booster vaccination in a few patients irrespective of the treatment intensity. CONCLUSIONS: Our data demonstrate improvements in humoral and cellular immunity following booster vaccination and support the assessment of the humoral vaccine response in patients with multiple myeloma until a threshold for protection against severe COVID-19 is validated. This strategy can allow the identification of patients who might benefit from additional protective measures (e.g. pre-exposure prophylaxis via passive immunisation).

CRP/Albumin Ratio and Glasgow Prognostic Score Provide Prognostic Information in Myelofibrosis Independently of MIPSS70-A Retrospective Study.

In myelofibrosis, the C-reactive protein (CRP)/albumin ratio (CAR) and the Glasgow Prognostic Score (GPS) add prognostic information independently of the Dynamic International Prognostic Scoring System (DIPSS). Their prognostic impact, if molecular aberrations are considered, is currently unknown. We performed a retrospective chart review of 108 MF patients (prefibrotic MF n = 30; primary MF n = 56; secondary MF n = 22; median follow-up 42 months). In MF, both a CAR > 0.347 and a GPS > 0 were associated with a shorter median overall survival (21 [95% CI 0-62] vs. 80 months [95% CI 57-103], p < 0.001 and 32 [95% CI 1-63] vs. 89 months [95% CI 65-113], p < 0.001). Both parameters retained their prognostic value after inclusion into a bivariate Cox regression model together with the dichotomized Mutation-Enhanced International Prognostic Scoring System (MIPSS)-70: CAR > 0.374 HR 3.53 [95% CI 1.36-9.17], p = 0.0095 and GPS > 0 HR 4.63 [95% CI 1.76-12.1], p = 0.0019. An analysis of serum samples from an independent cohort revealed a correlation of CRP with levels of interleukin-1ß and albumin with TNF-α, and demonstrated that CRP was correlated to the variant allele frequency of the driver mutation, but not albumin. Albumin and CRP as parameters readily available in clinical routine at low costs deserve further evaluation as prognostic markers in MF, ideally by analyzing data from prospective and multi-institutional registries. Since both albumin and CRP levels reflect different aspects of MF-associated inflammation and metabolic changes, our study further highlights that combining both parameters seems potentially useful to improve prognostication in MF.

[How Myelodysplastic Syndrome is Diagnosed]. / Wie werden myelodysplastische Syndrome diagnostiziert?

How Myelodysplastic Syndrome is Diagnosed Abstract. Even in the area of molecular medicine, the diagnosis of myelodysplastic syndromes (MDS) is based on the morphological evaluation of the bone marrow and the analysis of conventional metaphase cytogenetics. The same holds true for classification according to WHO 2016 and prognostication according to the Revised International Prognostic Scoring System (IPSS-R). History and physical examination together with laboratory analyses and a thorough evaluation of the peripheral blood smear provide clues with regard to the differential diagnosis of cytopenic states, before a bone marrow puncture is performed. If a case of MDS is suspected, the basic evaluation relies on both cytology of the aspirate and histology of a trephine biopsy, which should, together with the peripheral blood smear, be regarded as complementary methods for the evaluation of the myeloid compartment of the hematopoietic system. Conventional metaphase cytogenetics represent the second essential diagnostic tool. These methods can be supplemented on an individual basis by flow cytometric studies, certain molecular techniques (fluorescence in situ hybridisation [FISH] and single nucleotide polymorphism [SNP] arrays), which allow a more sensitive detection of genomic changes on the chromosomal level and the comprehensive detection of mutations in genes associated with myeloid neoplasia by next generation sequencing (NGS). Up to now, determining the mutational status is only mandatory in the diagnosis of MDS-forms with ringed sideroblasts, where the detection of a SF3B1 mutation allows the diagnosis in cases with> 5% ringed sideroblasts. However, the role of NGS-based comprehensive mutational analysis is expanding and it may expected for the future, that comprehensive myeloid NGS panels will be used in a standardized manner for the diagnostic work-up including refined prognostication, the identification of druggable targets and for individualized monitoring of the minimal residual disease remaining after hematopoietic stem cells transplantation.

Addition of lenalidomide to intensive treatment in younger and middle-aged adults with newly diagnosed AML: the HOVON-SAKK-132 trial.

Lenalidomide, an antineoplastic and immunomodulatory drug, has therapeutic activity in acute myeloid leukemia (AML), but definitive studies about its therapeutic utility have been lacking. In a phase 3 study, we compared 2 induction regimens in newly diagnosed patients age 18 to 65 years with AML: idarubicine-cytarabine (cycle 1) and daunorubicin and intermediate-dose cytarabine (cycle 2) without or with lenalidomide (15 mg orally on days 1-21). One final consolidation cycle of chemotherapy or autologous stem cell transplantation (auto-SCT) or allogeneic SCT (allo-SCT) was provided according to a prognostic risk and minimal residual disease (MRD)-adapted approach. Event-free survival (EFS; primary end point) and other clinical end points were assessed. A second random assignment in patients in complete response or in complete response with incomplete hematologic recovery after cycle 3 or auto-SCT involved 6 cycles of maintenance with lenalidomide (10 mg on days 1-21) or observation. In all, 392 patients were randomly assigned to the control group, and 388 patients were randomly assigned to lenalidomide induction. At a median follow-up of 41 months, the study revealed no differences in outcome between the treatments (EFS, 44% ± 2% standard error and overall survival, 54% ± 2% at 4 years for both arms) although in an exploratory post hoc analysis, a lenalidomide benefit was suggested in SRSF2-mutant AML. In relation to the previous Dutch-Belgian Hemato-Oncology Cooperative Group and Swiss Group for Clinical Cancer Research (HOVON-SAKK) studies that used a similar 3-cycle regimen but did not pursue an MRD-guided approach, these survival estimates compare markedly more favorably. MRD status after cycle 2 lost prognostic value in intermediate-risk AML in the risk-adjusted treatment context. Maintenance with lenalidomide showed no apparent effect on relapse probability in 88 patients randomly assigned for this part of the study.

Guideline-based indicators for adult patients with myelodysplastic syndromes.

Myelodysplastic syndromes (MDSs) represent a heterogeneous group of hematological stem cell disorders with an increasing burden on health care systems. Evidence-based MDS guidelines and recommendations (G/Rs) are published but do not necessarily translate into better quality of care if adherence is not maintained in daily clinical practice. Guideline-based indicators (GBIs) are measurable elements for the standardized assessment of quality of care and, thus far, have not been developed for adult MDS patients. To this end, we screened relevant G/Rs published between 1999 and 2018 and aggregated all available information as candidate GBIs into a formalized handbook as the basis for the subsequent consensus rating procedure. An international multidisciplinary expert panel group (EPG) of acknowledged MDS experts (n = 17), health professionals (n = 7), and patient advocates (n = 5) was appointed. The EPG feedback rates for the first and second round were 82% (23 of 28) and 96% (26 of 27), respectively. A final set of 29 GBIs for the 3 domains of diagnosis (n = 14), therapy (n = 8), and provider/infrastructural characteristics (n = 7) achieved the predefined agreement score for selection (>70%). We identified shortcomings in standardization of patient-reported outcomes, toxicity, and geriatric assessments that need to be optimized in the future. Our GBIs represent the first comprehensive consensus on measurable elements addressing best practice performance, outcomes, and structural resources. They can be used as a standardized instrument with the goal of assessing, comparing, and fostering good quality of care within clinical development cycles in the daily care of adult MDS patients.

Lymphopenia at diagnosis is highly prevalent in myelodysplastic syndromes and has an independent negative prognostic value in IPSS-R-low-risk patients.

Lymphopenia is associated with an increased mortality in several medical conditions. Its prognostic impact in myelodysplastic syndromes (MDS) is less well studied. Hence, we analyzed 1023 patients from the Düsseldorf MDS-registry with regard to the absolute lymphocyte count (ALC) at diagnosis. An ALC below the median of the population (1.2 × 109/l) was associated with lower counts of neutrophils (median 1.35 vs. 1.92 × 109/l, p < 0.001) and platelets (median 100 vs. 138 × 109/l, p < 0.001) and with a significant lower overall survival in univariate analysis (whole cohort: median 36 vs. 46 months, p = 0.016; 721 patients without hematopoietic stem cell transplantation or induction chemotherapy: median 36 vs. 56 months, p = 0.001). For low-risk MDS according to IPSS-R, an ALC < 1.2 × 109/l was of additional prognostic value in a multivariate Cox regression model together with age (< or ≥65 years) and LDH (< or ≥normal value of 240 U/l; HR 1.46, 95% CI: 1.03-2.08, p = 0.033). These data support the hypothesis of subtle but clinical relevant changes of the adaptive immune system in MDS. Further studies are necessary to identify the ALC cut-off best suitable for prognostication and the mechanisms responsible for the impairment of lymphoid homeostasis in MDS.

Improving the efficacy of proteasome inhibitors in the treatment of renal cell carcinoma by combination with the human immunodeficiency virus (HIV)-protease inhibitors lopinavir or nelfinavir.

OBJECTIVES: To assess the potential of second-generation proteasome inhibition by carfilzomib and its combination with the human immunodeficiency virus (HIV) protease inhibitors (HIV-PIs) lopinavir and nelfinavir in vitro for improved treatment of clear cell renal cell cancer (ccRCC). MATERIALS AND METHODS: Cytotoxicity, reactive oxygen species (ROS) production, and unfolded protein response (UPR) activation of proteasome inhibitors, HIV-PIs, and their combination were assessed in three cell lines and primary cells derived from three ccRCC tumours by MTS assay, flow cytometry, quantitative reverse transcriptase-polymerase chain reaction and western blot, respectively. Proteasome activity was determined by activity based probes. Flow cytometry was used to assess apoptosis by annexin V/propidium iodide assay and ATP-binding cassette sub-family B member 1 (ABCB1) activity by MitoTracker™ Green FM efflux assay (Thermo Fisher Scientific, MA, USA). RESULTS: Lopinavir and nelfinavir significantly increased the cytotoxic effect of carfilzomib in all cell lines and primary cells. ABCB1 efflux pump inhibition, induction of ROS production, and UPR pre-activation by lopinavir were identified as underlying mechanisms of this strong synergistic effect. Combined treatment led to unresolved protein stress, increased activation of pro-apoptotic UPR pathway, and a significant increase in apoptosis. CONCLUSION: The combination of the proteasome inhibitor carfilzomib and the HIV-PIs lopinavir and nelfinavir has a strong synergistic cytotoxic activity against ccRCCin vitro at therapeutically relevant drug concentrations. This effect is most likely explained by synergistic UPR triggering and ABCB1-modulation caused by HIV-PIs. Our findings suggest that combined treatment of second-generation proteasome inhibitors and HIV-PIs should be investigated in patients with metastatic RCC within a clinical trial.

The novel ß2-selective proteasome inhibitor LU-102 synergizes with bortezomib and carfilzomib to overcome proteasome inhibitor resistance of myeloma cells.

Proteasome inhibitor resistance is a challenge for myeloma therapy. Bortezomib targets the ß5 and ß1 activity, but not the ß2 activity of the proteasome. Bortezomib-resistant myeloma cells down-regulate the activation status of the unfolded protein response, and up-regulate ß2 proteasome activity. To improve proteasome inhibition in bortezomib-resistant myeloma and to achieve more efficient UPR activation, we have developed LU-102, a selective inhibitor of the ß2 proteasome activity. LU-102 inhibited the ß2 activity in intact myeloma cells at low micromolar concentrations without relevant co-inhibition of ß1 and ß5 proteasome subunits. In proteasome inhibitor-resistant myeloma cells, significantly more potent proteasome inhibition was achieved by bortezomib or carfilzomib in combination with LU-102, compared to bortezomib/carfilzomib alone, resulting in highly synergistic cytotoxic activity of the drug combination via endoplasmatic reticulum stress-induced apoptosis. Combining bortezomib/carfilzomib with LU-102 significantly prolonged proteasome inhibition and increased activation of the unfolded protein response and IRE1-a activity. IRE1-α has recently been shown to control myeloma cell differentiation and bortezomib sensitivity (Leung-Hagesteijn, Cancer Cell 24:3, 289-304). Thus, ß2-selective proteasome inhibition by LU-102 in combination with bortezomib or carfilzomib results in synergistic proteasome inhibition, activation of the unfolded protein response, and cytotoxicity, and overcomes bortezomib/carfilzomib resistance in myeloma cells in vitro.

Decreased generation of procoagulant platelets detected by flow cytometric analysis in patients with bleeding diathesis.

BACKGROUND: A clinically relevant bleeding diathesis is a frequent diagnostic challenge, which sometimes remains unexplained despite extensive investigations. The aim of our work was to evaluate the diagnostic utility of functional platelet testing by flow cytometry in this context. METHODS: In case of negative results after standard laboratory workup, flow cytometric analysis (FCA) of platelet function was done. We performed analysis of surface glycoproteins Ibα, IIb, IIIa; P-selectin expression and PAC-1 binding after graded doses of ADP, collagen, and thrombin; content/secretion of dense granules; and ability to generate procoagulant platelets. RESULTS: Of 437 patients investigated with standard tests between January 2007 and December 2011, we identified 67 (15.3%) with high bleeding scores and nondiagnostic standard laboratory workup including platelet aggregation studies. Among these patients, FCA revealed some potentially causative platelet defects: decreased dense granule content/secretion (n = 13); decreased α-granule secretion induced by ADP (n = 10), convulxin (n = 4), or thrombin (n = 3); decreased fibrinogen receptor activation induced by ADP (n = 11), convulxin (n = 11), or thrombin (n = 8); and decreased generation of COAT platelets, that is, highly procoagulant platelets induced by simultaneous activation with collagen and thrombin (n = 16). CONCLUSION: Our work confirms that storage pool defects are frequent in patients with a bleeding diathesis and normal coagulation and platelet aggregations studies. Additionally, FCA is able to identify discrete platelet activation defects. In particular, we show for the first time that a relevant proportion of these patients has an isolated impaired ability to generate COAT platelets--a conceptually new defect in platelet procoagulant activity, which is missed by conventional laboratory workup.

Decreased generation of procoagulant platelets detected by flow cytometric analysis in patients with bleeding diathesis.

Background: A clinically relevant bleeding diathesis is a frequent diagnostic challenge, which sometimes remains unexplained despite extensive investigations. The aim of our work was to evaluate the diagnostic utility of functional platelet testing by flow cytometry in this context. Methods: In case of negative results after standard laboratory work-up, flow cytometric analysis (FCA) of platelet function was done. We performed analysis of surface glycoproteins (GP) Ibα, IIb, IIIa; P-selectin expression and PAC-1 binding after graded doses of ADP, collagen and thrombin; content/secretion of dense granules; ability to generate procoagulant platelets. Results: Out of 437 patients investigated with standard tests between January 2007 and December 2011, we identified 67 (15.3%) with high bleeding scores and non-diagnostic standard laboratory work-up including platelet aggregation studies. Among these patients FCA revealed some potentially causative platelet defects: decreased dense-granule content/secretion (n=13); decreased alpha-granule secretion induced by ADP (n=10), convulxin (n=4) or thrombin (n=3); decreased fibrinogen-receptor activation induced by ADP (n=11), convulxin (n=11) or thrombin (n=8); decreased generation of COAT-platelets, i.e. highly procoagulant platelets induced by simultaneous activation with collagen and thrombin (n=16). Conclusion: Our work confirms that storage pool defects are frequent in patients with a bleeding diathesis and normal coagulation and platelet aggregations studies. Additionally, flow cytometric analysis is able to identify discrete platelet activation defects. In particular, we show for the first time that a relevant proportion of these patients has an isolated impaired ability to generate COAT-platelets - a conceptually new defect in platelet procoagulant activity, that is missed by conventional laboratory work-up. © 2014 Clinical Cytometry Society.

Aplastic anemia and concomitant autoimmune diseases.

The association of aplastic anemia (AA) with other autoimmune diseases (AID) has been described but so far not systematically evaluated. We assessed the incidence and the outcome of concomitant AID in a retrospective, single-center study of 243 patients with severe AA treated between 1974 and 2006 with either immunosuppression (186) or hematopoietic stem cell transplantation (57) and a median follow-up time of 9.3 years (0-33). Clinically manifest AID were observed in 24 out of 243 (10 +/- 3.7%) patients. Age at diagnosis of AA was significantly younger in patients without AID compared to patients with AID (median, 20 versus 52 years; P < 0.001). In 12 patients where the diagnosis of AID was done before AA therapy, response to antithymocyte globulin was good for AA (ten out of 12) but not for AID (2 out of 12). In 13 patients in which AID occurred after first-line therapy, the median time to the AID was 7 years (range 3 months-27.5 years).

The fibroblast: sentinel cell and local immune modulator in tumor tissue.

Development and progression of epithelial malignancies are frequently accompanied by complex phenotypic alterations of resident tissue fibroblasts. Some of these changes, such as myofibroblastic differentiation and an oncofetal extracellular matrix (ECM) expression profile, are also implicated in inflammation and tissue repair. Studies over the past decade revealed the relevance of reciprocal interactions between tumor cells and tumor-associated host fibroblasts (TAF) in the malignant process. In many tumors, a considerable fraction of the inflammatory infiltrate is located within the fibroblast- and ECM-rich stromal compartment. However, while fibroblasts are known as "sentinel cells" in various nonneoplastic diseases, where they often regulate the composition and function of recruited leucocytes, they are hardly considered active participants in the inflammatory host response in tumors. This article focuses on the functional impact of TAF on immune cells. The complex network of immune-modulating effects transduced by TAF and TAF-derived factors is highlighted, and recent reports that support the hypothesis that TAF are involved in the inflammatory response and immune suppression in tumors are reviewed. The role of TAF-dependent ECM remodeling and TAF-derived peptide growth factors, cytokines, and chemokines in the immune modulation is stressed and the idea of TAF as an important therapeutic target is emphasized.

Tumor-associated fibroblasts recruit blood monocytes into tumor tissue.

Tumor-associated fibroblasts (TAF) and tumor-associated macrophages are the main stromal components in desmoplastic breast tumors. These host cell types were extensively studied individually with regard to tumor development and progression but little is known about their reciprocal interactions. To elucidate the role of TAF in the recruitment of monocytes (MO) we designed a 3D co-culture system of multicellular fibroblast spheroids of different origin, co-cultured with MO suspensions from healthy donors. Spheroids of tumor-derived but not of normal fibroblasts were extensively infiltrated by MO. A linear correlation between number of infiltrated MO and number of MO applied per spheroid was shown, indicating a distinct migratory MO subpopulation (approximately 15%) within the peripheral blood MO pool. Our data imply that MO migration into fibroblastic tumor areas may partially result from high expression of CCL2 (monocyte chemotactic protein-1), which was regulated by endogenous IL-6 as shown by neutralization experiments. The effect of CCL2 on MO migration was inhibited by CCL2 neutralizing antibody in tumor-derived fibroblast conditioned media in a Boyden chamber migration assay but not in spheroid culture. While this phenomenon needs further evaluation, our data clearly support the concept of fibroblasts as "sentinel cells" relevant for tumor progression.