Do clinical trials prepare to fail by failing to prepare? An examination of MS trials and recommendations for patient-reported outcome measure selection.

BACKGROUND: Many clinical trials use patient-reported outcome (PRO) measures, which can influence treatment decision-making, drug approval and label claims. Given that many PRO measure options exist, and there are conceptual and contextual complexities with PRO measurement, we aimed to evaluate how and why specific PRO measures have been selected for pivotal multiple sclerosis (MS) clinical trials. Specifically, we aimed to identify the reasons documented for PRO measure selection in contemporary phase III MS disease-modifying treatment (DMT) clinical trials. METHODS: We searched for phase III clinical trials of MS DMTs published between 2015 and 2021 and evaluated trial protocols, or primary publications where available, for PRO measure selection information. Specifically, we examined study documents for their clarification of clinical concepts measured, definitions of concepts measured, explanations of which PRO measures were considered, why specific PRO measures were chosen, and trade-offs in PRO measure selection. RESULTS: We identified 1705 abstracts containing 61 unique phase III MS DMT clinical trials. We obtained and examined 27/61 trial protocols. Six protocols were excluded: four contained no mention of PRO measures and two contained redacted sections preventing adequate assessment, leaving 21 protocols for assessment. For the remaining 34 trials (61-27), we retrieved 31 primary publications; 15 primary publications mentioned the use of a PRO measure. None of the 36 clinical trials that mentioned the use of PRO measures (21 protocols and 15 primary publications) documented clear PRO or clinical outcome assessment (COA) measurement strategies, provided clear justifications for PRO selection, or reasons why specific PRO measures were selected when alternatives existed. CONCLUSION: PRO measure selection for clinical trials is not evidence-based or underpinned by structured systematic approaches. This represents a critical area for study design improvement as PRO measure results directly affect patient care, PRO measurement has conceptual and contextual complexities, and there is a wide range of options when selecting a PRO measure. We recommend trial designers use formal approaches for PRO measure selection to ensure PRO measurement-based decisions are optimised. We provide a simple, logical, five-stage approach for PRO measure selection in clinical trials.

Measuring Fatigue in Multiple Sclerosis: There may be Trouble Ahead.

INTRODUCTION: Poorly developed patient-reported outcome measures (PROs) risk type-II errors (i.e. false negatives) in clinical trials, resulting in erroneous failure to achieve trial endpoints. Validity is a fundamental requirement of fit-for-purpose PROs, with the main determinant of validity being the PROs items, i.e. content validity. Here, we sought to identify fatigue PRO instruments used in multiple sclerosis (MS) studies and to assess the extent to which their development satisfied current content validity standards. METHODS: We searched Embase® and Medline® for MS studies using fatigue-based PROs. Abstracts were screened, PROs identified, and their relevant development papers assessed against seven Consensus Standards for Measurement Instruments (COSMIN) criteria for content development. RESULTS: From 3814 abstracts, 18 fatigue PROs met our inclusion criteria. Most PROs did not satisfy at least one COSMIN content validity standard. Frequent omissions during PRO development include: clearly defined constructs; conceptual frameworks; qualitative research in representative samples; and literature reviews. PRO development quality has improved significantly since FDA guidance was published (U = 10.0, p = 0.02). However, scatterplots and correlations between PRO COSMIN scores and citation frequency (rho = - 0.62) and clinical trials usage (rho =  + 0.18) implied that PRO quality is unrelated to choice. COSMIN scores implied that the Fatigue Symptoms and Impact Questionnaire-Relapsing Multiple Sclerosis (FSIQ-RMS) and Neurological Fatigue Index-Multiple Sclerosis (NFI-MS) had the strongest evidence for adequate content validity. CONCLUSION: Most existing fatigue PROs do not meet COSMIN content validity requirements. Although two PROs scored well on aggregate (NFI-MS and FSIQ-RMS), our subsequent evaluation of the item sets that generated their scores implied that both PROs have weaker content validity than COSMIN suggests. This indicates that COSMIN criteria require further development, and raises significant concerns about how we have measured one of the most common and burdensome MS symptoms. A detailed head-to-head psychometric evaluation is needed to determine the impact of different PRO development qualities and the implications of the problems implied by our analyses, on measurement performance.

In MS clinical trials, impacts such as fatigue, walking ability, and quality of life, are measured using questionnaires­called patient-reported outcome measures­completed by people living with MS. The quality of these measures is fundamentally important. If poor quality patient-reported outcome measures are used, treatment benefits are easily missed or underestimated.We studied the quality of 18 fatigue patient-reported outcome measures previously used in MS studies. Specifically, we studied how the questionnaire questions were developed and scored them against recognised quality control standards. In general, the patient-reported outcome measures were poor. Only two scored reasonably well. One common weakness was that people living with MS were not involved during patient-reported outcome measure development. We also conducted novel examinations that went beyond the quality control standards. These test how well the questions relate back to the MS impacts they claim to measure. We found even the two best patient-reported outcome measures were poor.Our study had two findings. First, patient-reported outcome measures of MS fatigue are poor. Second, current standards for testing patient-reported outcome measure development are too easy to satisfy, overestimate patient-reported outcome measure quality, and need updating. Therefore, the ways we measure MS fatigue, one of the most common and burdensome MS symptoms, are scientifically weak. Measuring fatigue in multiple sclerosis: there may be trouble ahead­a video abstract (MP4 125165 KB).

Development and usability testing of your MS questionnaire: A patient-based digital tool to monitor symptoms of multiple sclerosis.

Objectives: We describe the development of Your Multiple Sclerosis Questionnaire and present the real-world usability testing results of Your Multiple Sclerosis Questionnaire. Methods: The Your Multiple Sclerosis Questionnaire tool was developed in four stages to collect feedback from people living with MS (plwMS), patient organizations, and clinicians on content, format, and applicability. To assess its usability, 13 clinicians across 7 countries completed an online survey after using the tool with plwMS in a total of 261 consultations from September, 2020 to July, 2021. Results: The initial Your Multiple Sclerosis Questionnaire version was based on findings from previous research developing MSProDiscuss™, a clinician-completed tool. Subsequently, insights from plwMS obtained during cognitive debriefing, patient councils and advisory boards led to changes including the addition of mood and sexual problems and the definition of relapse. All 13 clinicians completed the individual survey, whereas 10 clinicians completed the final survey. Clinicians "strongly agreed" or "agreed" that Your Multiple Sclerosis Questionnaire was easy to use and understand (98.5%; 257/261 patient consultations). The clinicians were willing to use the tool again with the same patient (98.1%; 256/261 patient consultations). All clinicians who completed the final survey (100%; 10/10) reported the tool to have a positive influence on their clinical practice, helped patients engage with their MS, facilitated discussion with patients, and complemented neurological assessment. Conclusion: Your Multiple Sclerosis Questionnaire benefits both plwMS and clinicians by facilitating a structured discussion and engaging the plwMS to self-monitor and self-manage. Your Multiple Sclerosis Questionnaire is compatible with telemedicine practice and integration of the tool into electronic health records would enable tracking of the disease evolution and individual monitoring of MS symptoms over time.

MSProDiscuss™ Clinical Decision Support Tool for Identifying Multiple Sclerosis Progression.

This article describes the rationale for the development of the MSProDiscuss™ clinical decision support (CDS) tool, its development, and insights into how it can help neurologists improve care for patients with multiple sclerosis (MS). MS is a progressive disease characterized by heterogeneous symptoms and variable disease course. There is growing consensus that MS exists on a continuum, with overlap between relapsing-remitting and secondary progressive phenotypes. Evidence demonstrates that neuroaxonal loss occurs from the outset, that progression can occur independent of relapse activity, and that continuous underlying pathological processes may not be reflected by inflammatory activity indicative of the patient's immune response. Early intervention can benefit patients, and there is a need for a tool that assists physicians in rapidly identifying subtle signs of MS progression. MSProDiscuss, developed with physicians and patients, facilitates a structured approach to patient consultations. It analyzes multidimensional data via an algorithm to estimate the likelihood of progression (the MSProDiscuss score), the contribution of various symptoms, and the impact of symptoms on daily living, enabling a more personalized approach to treatment and disease management. Data from CDS tools such as MSProDiscuss offer new insights into disease course and facilitate informed decision-making and a holistic approach to MS patient care.

Symptom Interconnectivity in Multiple Sclerosis: A Narrative Review of Potential Underlying Biological Disease Processes.

INTRODUCTION: Fatigue, cognitive impairment, depression, and pain are highly prevalent symptoms in multiple sclerosis (MS). These often co-occur and may be explained by a common etiology. By reviewing existing literature, we aimed to identify potential underlying biological processes implicated in the interconnectivity between these symptoms. METHODS: A literature search was conducted to identify articles reporting research into the biological mechanisms responsible for the manifestation of fatigue, cognitive impairment, depression, and pain in MS. PubMed was used to search for articles published from July 2011 to July 2021. We reviewed and assessed findings from the literature to identify biological processes common to the symptoms of interest. RESULTS: Of 693 articles identified from the search, 252 were selected following screening of titles and abstracts and assessing reference lists of review articles. Four biological processes linked with two or more of the symptoms of interest were frequently identified from the literature: (1) direct neuroanatomical changes to brain regions linked with symptoms of interest (e.g., thalamic injury associated with cognitive impairment, fatigue, and depression), (2) pro-inflammatory cytokines associated with so-called 'sickness behavior,' including manifestation of fatigue, transient cognitive impairment, depression, and pain, (3) dysregulation of monoaminergic pathways leading to depressive symptoms and fatigue, and (4) hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis as a result of pro-inflammatory cytokines promoting the release of brain noradrenaline, serotonin, and tryptophan, which is associated with symptoms of depression and cognitive impairment. CONCLUSION: The co-occurrence of fatigue, cognitive impairment, depression, and pain in MS appears to be associated with a common set of etiological factors, namely neuroanatomical changes, pro-inflammatory cytokines, dysregulation of monoaminergic pathways, and a hyperactive HPA axis. This association of symptoms and biological processes has important implications for disease management strategies and, eventually, could help find a common therapeutic pathway that will impact both inflammation and neuroprotection.

Patient-reported outcome measures in MS: Do development processes and patient involvement support valid quantification of clinically important variables?

Background: Patient-reported outcomes (PROs) are widely measured in multiple sclerosis (MS) studies. However, the quality of instrument development processes varies, raising concerns about the meaningfulness of associated data. Objectives: To review the development of selected PROs commonly used in MS studies, including definitions of the concepts measured, use of conceptual frameworks, and degree of input from people living with MS (PlwMS). To gain insights and recommendations from PlwMS on their experience with these PROs. Methods: We assessed 6 PROs (FSIQ-RMS, modified-FIS, MSQoL-54, Leeds 8-item MSQoL, MSIS-29 and EQ-5D) for alignment with regulatory and scientific requirements on PRO structure/development. PlwMS evaluated the degree to which the PROs reflect disease aspects they perceive important. Results: Definitions, clarifications and conceptualisations of the measurement variables were often lacking. PlwMS were variably involved in PRO development. Ethnic diversity was rarely documented. PlwMS identified individualisation, ease of understanding, time burden, and mode of administration as factors affecting PRO usability. Conclusions: To date, the PRO development process has consistently lacked clear definitions of concepts of interest, use of conceptual frameworks and patient involvement, thereby compromising the validity of data they generate. PRO instrument development must be conducted more robustly to maximise the value of pivotal clinical trials.

Angiostatic and chemotactic activities of the CXC chemokine CXCL4L1 (platelet factor-4 variant) are mediated by CXCR3.

We investigated possible cellular receptors for the human CXC chemokine platelet factor-4 variant/CXCL4L1, a potent inhibitor of angiogenesis. We found that CXCL4L1 has lower affinity for heparin and chondroitin sulfate-E than platelet factor-4 (CXCL4) and showed that CXCL10 and CXCL4L1 could displace each other on microvascular endothelial cells. Labeled CXCL4L1 also bound to CXCR3A- and CXCR3B-transfectants and was displaced by CXCL4L1, CXCL4, and CXCL10. The CXCL4L1 anti-angiogenic activity was blocked by anti-CXCR3 antibodies (Abs) in the Matrigel and cornea micropocket assays. CXCL4L1 application in CXCR3(-/-) or in wild-type mice treated with neutralizing anti-CXCR3 Abs, resulted in reduced inhibitory activity of CXCL4L1 on tumor growth and vascularization of Lewis lung carcinoma. Furthermore, CXCL4L1 and CXCL4 chemoattracted activated T cells, human natural killer cells, and human immature dendritic cells (DCs). Migration of DCs toward CXCL4 and CXCL4L1 was desensitized by preincubation with CXCL10 and CXCL11, inhibited by pertussis toxin, and neutralized by anti-CXCR3 Abs. Chemotaxis of T cells, natural killer cells, and DCs is likely to contribute to the antitumoral action. However, the in vivo data indicate that the angiostatic property of CXCL4L1 is equally important in retarding tumor growth. Thus, both CXCR3A and CXCR3B are implicated in the chemotactic and vascular effects of CXCL4L1.

The role of the CXC chemokines platelet factor-4 (CXCL4/PF-4) and its variant (CXCL4L1/PF-4var) in inflammation, angiogenesis and cancer.

Chemokines are chemotactic cytokines which recruit leukocytes to inflammatory sites. They also affect tumor development and metastasis by acting as growth factor, by attracting pro- or anti-tumoral leukocytes or by influencing angiogenesis. Platelet factor-4 (CXCL4/PF-4) was the first chemokine shown to inhibit angiogenesis. CXCL4L1/PF-4var, recently isolated from thrombin-stimulated platelets, differing from authentic CXCL4/PF-4 in three carboxy-terminally located amino acids, was found to be more potent than CXCL4/PF-4 in inhibiting angiogenesis and tumor growth. Both glycosaminoglycans (GAG) and CXCR3 are implicated in the activities of the PF-4 variants. This report reviews the current knowledge on the role of CXCL4/PF-4 and CXCL4L1/PF-4var in physiological and pathological processes. In particular, the role of CXCL4/PF-4 in cancer, heparin-induced thrombocytopenia and atherosclerosis is described.

The COOH-terminal peptide of platelet factor-4 variant (CXCL4L1/PF-4var47-70) strongly inhibits angiogenesis and suppresses B16 melanoma growth in vivo.

Chemokines influence tumor growth directly or indirectly via both angiogenesis and tumor-leukocyte interactions. Platelet factor-4 (CXCL4/PF-4), which is released from alpha-granules of activated platelets, is the first described angiostatic chemokine. Recently, it was found that the variant of CXCL4/PF-4 (CXCL4L1/PF-4var) could exert a more pronounced angiostatic and antitumoral effect than CXCL4/PF-4. However, the molecular mechanisms of the angiostatic activities of the PF-4 forms remain partially elusive. Here, we studied the biological properties of the chemically synthesized COOH-terminal peptides of CXCL4/PF-4 (CXCL4/PF-4(47-70)) and CXCL4L1/PF-4var (CXCL4L1/PF-4var(47-70)). Both PF-4 peptides lacked monocyte and lymphocyte chemotactic activity but equally well inhibited (25 nmol/L) endothelial cell motility and proliferation in the presence of a single stimulus (i.e., exogenous recombinant fibroblast growth factor-2). In contrast, when assayed in more complex angiogenesis test systems characterized by the presence of multiple mediators, including in vitro wound-healing (2.5 nmol/L versus 12.5 nmol/L), Matrigel (60 nmol/L versus 300 nmol/L), and chorioallantoic membrane assays, CXCL4L1/PF-4var(47-70) was found to be significantly (5-fold) more angiostatic than CXCL4/PF-4(47-70). In addition, low (7 microg total) doses of intratumoral CXCL4L1/PF-4var(47-70) inhibited B16 melanoma growth in mice more extensively than CXCL4/PF-4(47-70). This antitumoral activity was predominantly mediated through inhibition of angiogenesis (without affecting blood vessel stability) and induction of apoptosis, as evidenced by immunohistochemical and fluorescent staining of B16 tumor tissue. In conclusion, CXCL4L1/PF-4var(47-70) is a potent antitumoral and antiangiogenic peptide. These results may represent the basis for the design of CXCL4L1/PF-4var COOH-terminal-derived peptidomimetic anticancer drugs.

Expression of angiostatic platelet factor-4var/CXCL4L1 counterbalances angiogenic impulses of vascular endothelial growth factor, interleukin-8/CXCL8, and stromal cell-derived factor 1/CXCL12 in esophageal and colorectal cancer.

Chemokines influence tumor progression through regulation of leukocyte chemotaxis, angiogenesis, and metastasis. In this study, the regulated expression of angiogenic (stromal cell-derived factor [SDF]-1/CXCL12 and interleukin [IL]-8/CXCL8) and angiostatic (platelet factor [PF]-4var/CXCL4L1 and inducible protein [IP-10]/CXCL10) chemokines was examined in human colorectal and esophageal cancer. In HCT 116 and HCT-8 colorectal adenocarcinoma cells, the production of IL-8 immunoreactivity was up-regulated by IL-1beta, tumor necrosis factor (TNF)-alpha, the toll-like receptor (TLR) ligands double-stranded RNA and peptidoglycan and phorbol ester. Increased PF-4 and synergistic IL-8 and IP-10 induction in carcinoma cells after stimulation with IL-1beta plus TNF-alpha or interferon-gamma was demonstrated by enzyme-linked immunosorbent assay, quantitative reverse transcriptase polymerase chain reaction, or immunocytochemistry. In addition, IL-8 from HT-29 colorectal adenocarcinoma cells was molecularly identified as intact chemokine, as well as NH(2)-terminally truncated, more active IL-8(6-77). The presence of PF-4var, SDF-1, and vascular endothelial growth factor (VEGF) was evidenced by immunohistochemistry in surgical samples from 51 patients operated on for colon adenocarcinoma (AC), esophageal AC, or esophageal squamous cell carcinoma (SCC). PF-4var was strongly detected in colorectal cancer, whereas its expression in esophageal cancer was rather weak. Staining for SDF-1 was almost negative in esophageal SCC, whereas a more intense and frequent staining was observed in AC of the esophagus and colon. Staining for VEGF was moderately to strongly positive in all 3 types of cancer, although less prominent in esophageal AC. The heterogenous expression of angiogenic (IL-8, SDF-1) as well as angiostatic (IP-10, PF-4var) chemokines not only within the tumor and between the different cases but also between the different tumor cell types may indicate a distinct role of the various chemokines in the complex process of tumor development.

Membrane rafts are involved in intracellular miconazole accumulation in yeast cells.

Azoles inhibit ergosterol biosynthesis, resulting in ergosterol depletion and accumulation of toxic 14alpha-methylated sterols in membranes of susceptible yeast. We demonstrated previously that miconazole induces actin cytoskeleton stabilization in Saccharomyces cerevisiae prior to induction of reactive oxygen species, pointing to an ancillary mode of action. Using a genome-wide agar-based screening, we demonstrate in this study that S. cerevisiae mutants affected in sphingolipid and ergosterol biosynthesis, namely ipt1, sur1, skn1, and erg3 deletion mutants, are miconazole-resistant, suggesting an involvement of membrane rafts in its mode of action. This is supported by the antagonizing effect of membrane raft-disturbing compounds on miconazole antifungal activity as well as on miconazole-induced actin cytoskeleton stabilization and reactive oxygen species accumulation. These antagonizing effects point to a primary role for membrane rafts in miconazole antifungal activity. We further show that this primary role of membrane rafts in miconazole action consists of mediating intracellular accumulation of miconazole in yeast cells.

Synergistic up-regulation of MCP-2/CCL8 activity is counteracted by chemokine cleavage, limiting its inflammatory and anti-tumoral effects.

Chemokines mediate the inflammatory response by attracting various leukocyte types. MCP-2/CC chemokine ligand 8 (CCL8) was induced at only suboptimal levels in fibroblasts and endothelial cells by IL-1beta or IFN-gamma, unless these cytokines were combined. IFN-gamma also synergized with the TLR ligands peptidoglycan (TLR2), dsRNA (TLR3) or LPS (TLR4). Under these conditions, intact MCP-2/CCL8(1-76) produced by fibroblasts was found to be processed into MCP-2/CCL8(6-75), which lacked chemotactic activity for monocytic cells. Furthermore, the capacity of MCP-2/CCL8(6-75) to increase intracellular calcium levels through CCR1, CCR2, CCR3 and CCR5 was severely reduced. However, the truncated isoform still blocked these receptors for other ligands. MCP-2/CCL8(6-75) induced internalization of CCR2, inhibited MCP-1/CCL2 and MCP-2/CCL8 ERK signaling and antagonized the chemotactic activity of several CCR2 ligands (MCP-1/CCL2, MCP-2/CCL8, MCP-3/CCL7). In contrast to MCP-3/CCL7, parvoviral delivery of MCP-2/CCL8 into B78/H1 melanoma failed to inhibit tumor growth, partially due to proteolytic cleavage into inactive MCP-2/CCL8 missing five NH(2)-terminal residues. However, in an alternative tumor model, using HeLa cells, MCP-2/CCL8 retarded tumor development. These data indicate that optimal induction and delivery of MCP-2/CCL8 is counteracted by converting this chemokine into a receptor antagonist, thereby losing its anti-tumoral potential.

The role of CXC chemokines and their receptors in cancer.

Chemokines, or chemotactic cytokines, and their receptors have been discovered as essential and selective mediators in leukocyte migration to inflammatory sites and to secondary lymphoid organs. Besides their functions in the immune system, they also play a critical role in tumor initiation, promotion and progression. There are four subgroups of chemokines: CXC, CC, CX(3)C, and C chemokine ligands. The CXC or alpha subgroup is further subdivided in the ELR(+) and ELR(-) chemokines. Members that contain the ELR motif bind to CXC chemokine receptor 2 (CXCR2) and are angiogenic. In contrast, most of the CXC chemokines without ELR motif bind to CXCR3 and are angiostatic. An exception is the angiogenic ELR(-)CXC chemokine stromal cell-derived factor-1 (CXCL12/SDF-1), which binds to CXCR4 and CXCR7 and is implicated in tumor metastasis. This review is focusing on the role of CXC chemokines and their receptors in tumorigenesis, including angiogenesis, attraction of leukocytes to tumor sites and induction of tumor cell migration and homing in metastatic sites. Finally, their therapeutic use in cancer treatment is discussed.

Stimulation of angiostatic platelet factor-4 variant (CXCL4L1/PF-4var) versus inhibition of angiogenic granulocyte chemotactic protein-2 (CXCL6/GCP-2) in normal and tumoral mesenchymal cells.

Chemokines affect inflammation and cancer through leukocyte attraction and angiogenesis. Here, we demonstrate that CXCL4L1/platelet factor-4 variant (PF-4var), a highly angiostatic chemokine, is poorly chemotactic for phagocytes and is inducible in monocytes by inflammatory mediators but remained undetectable in macrophages and neutrophils. In addition, CXCL4L1/PF-4var production by mesenchymal tumor cells was evidenced in vitro and in vivo by specific ELISA and immunohistochemistry. CXCL4L1/PF-4var, but not CXCL4/PF-4, was coinduced with the angiogenic chemokine CXCL6/granulocyte chemotactic protein-2 (GCP-2) by cytokines, e.g., IL-1beta and IL-17, in sarcoma cells, but not in diploid fibroblasts. Furthermore, the induction of CXCL6/GCP-2 in endothelial cells by IL-1beta was enhanced synergistically by TNF-alpha but inhibited by IFN-gamma, which synergized with IL-1beta to produce the angiostatic CXCL10/IFN-gamma-induced protein-10. These findings indicate that the equilibrium between angiostatic and angiogenic factors during inflammation and tumor progression is rather complex and differs depending on the chemokine, cell type, and stimulus. Selective intervention in the chemokine network may drastically disturb this delicate balance of angiogenesis and tissue repair. Application of angiostatic CXCL4L1/PF-4var without attraction of protumoral phagocytes may be beneficial in cancer therapy.

Proteolytic processing of CXCL11 by CD13/aminopeptidase N impairs CXCR3 and CXCR7 binding and signaling and reduces lymphocyte and endothelial cell migration.

CXCR3 ligands were secreted by tissue fibroblasts and peripheral blood-derived mononuclear leukocytes in response to interferon-gamma (IFN-gamma) and Toll-like receptor (TLR) ligands. Subsequent purification and identification revealed the presence of truncated CXCL11 variants missing up to 6 amino acids. In combination with CD26/dipeptidyl peptidase IV, the metalloprotease aminopeptidase N (APN), identical to the myeloid cell marker CD13, rapidly processed CXCL11, but not CXCL8, to generate truncated CXCL11 forms. Truncated CXCL11 had reduced binding, signaling, and chemotactic properties for lymphocytes and CXCR3- or CXCR7-transfected cells. CD13/APN-truncated CXCL11 failed to induce an intracellular calcium increase but was still able to bind and desensitize CXCR3 for intact CXCL11 signaling. CXCL11 efficiently bound to CXCR7, but CXCL11 was not able to induce calcium signaling or ERK1/2 or Akt phosphorylation through CXCR7. CD26-truncated CXCL11 failed to attract lymphocytes but still inhibited microvascular endothelial cell (HMVEC) migration. However, further processing of CXCL11 by CD13 resulted in significant reduction of inhibition of HMVEC migration. Taken together, during inflammation or cancer, CXCL11 processing by CD13 may lead to a reduced number of tumor-infiltrating lymphocytes and in a more angiogenic environment.