Minimal clinically important differences in the brief pain inventory in patients with bone metastases.

PURPOSE: The brief pain inventory (BPI) is often used to assess pain and functional interference as a result of pain in cancer patients. Minor improvements or deteriorations in BPI may be statistically significant due to large sample sizes but may not necessarily be clinically relevant. The purpose of this study was to determine the minimal clinically important differences (MCID) in the functional BPI in patients with pain due to bone metastases. METHODS: BPI scores were collected from patients with painful bone metastases who visited the Rapid Response Radiotherapy Program for palliative radiotherapy. Pain and functional interferences scores were also collected monthly for three months. Patients were categorized into "complete or partial response," "pain progression," and "indeterminate response" based on their pain scores as recommended by the latest consensus definitions. Anchor-based determination of MCIDs of functional interference scores was calculated by determining the difference between the mean follow-up scores and the mean baseline scores for patients from each of the three response groups. Distribution-based estimates were obtained utilizing 0.2, 0.3, and 0.5 standard deviation (SD) effect sizes and the standard error of measurement. The anchor-based method results were compared with the distribution-based method results. RESULTS: Statistically significant MCIDs were determined for all of the functional interference items of BPI for patients with "complete or partial response"; whereas, no statistically significant MCIDs in BPI scores could be determined for patients with "pain progression." Some of the functional interference items of BPI had statistically significant MCIDs for patients with "indeterminate response," although these were generally smaller than patients with complete or partial response. Using the distribution-based approach, an effect size of 0.5 SD was the closest estimate for determining the MCID for both patients with complete or partial response and those with indeterminate response. CONCLUSIONS: The MCIDs determined for pain improvement were rather large, where as statistically significant MCIDs could not be detected for pain deterioration. Knowledge of MCIDs utilizing the BPI will allow physicians to evaluate the impact of treatment (or no treatment) on a patient's functional abilities. Knowledge of MCIDs may allow for sample size determination in future clinical trials.

Rational design of a SOCS1-edited tumor-infiltrating lymphocyte therapy using CRISPR/Cas9 screens.

Cell therapies such as tumor-infiltrating lymphocyte (TIL) therapy have shown promise in the treatment of patients with refractory solid tumors, with improvement in response rates and durability of responses nevertheless sought. To identify targets capable of enhancing the antitumor activity of T cell therapies, large-scale in vitro and in vivo clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 screens were performed, with the SOCS1 gene identified as a top T cell-enhancing target. In murine CD8+ T cell-therapy models, SOCS1 served as a critical checkpoint in restraining the accumulation of central memory T cells in lymphoid organs as well as intermediate (Texint) and effector (Texeff) exhausted T cell subsets derived from progenitor exhausted T cells (Texprog) in tumors. A comprehensive CRISPR tiling screen of the SOCS1-coding region identified sgRNAs targeting the SH2 domain of SOCS1 as the most potent, with an sgRNA with minimal off-target cut sites used to manufacture KSQ-001, an engineered TIL therapy with SOCS1 inactivated by CRISPR/Cas9. KSQ-001 possessed increased responsiveness to cytokine signals and enhanced in vivo antitumor function in mouse models. These data demonstrate the use of CRISPR/Cas9 screens in the rational design of T cell therapies.

Combinations with Allosteric SHP2 Inhibitor TNO155 to Block Receptor Tyrosine Kinase Signaling.

PURPOSE: SHP2 inhibitors offer an appealing and novel approach to inhibit receptor tyrosine kinase (RTK) signaling, which is the oncogenic driver in many tumors or is frequently feedback activated in response to targeted therapies including RTK inhibitors and MAPK inhibitors. We seek to evaluate the efficacy and synergistic mechanisms of combinations with a novel SHP2 inhibitor, TNO155, to inform their clinical development. EXPERIMENTAL DESIGN: The combinations of TNO155 with EGFR inhibitors (EGFRi), BRAFi, KRASG12Ci, CDK4/6i, and anti-programmed cell death-1 (PD-1) antibody were tested in appropriate cancer models in vitro and in vivo, and their effects on downstream signaling were examined. RESULTS: In EGFR-mutant lung cancer models, combination benefit of TNO155 and the EGFRi nazartinib was observed, coincident with sustained ERK inhibition. In BRAFV600E colorectal cancer models, TNO155 synergized with BRAF plus MEK inhibitors by blocking ERK feedback activation by different RTKs. In KRASG12C cancer cells, TNO155 effectively blocked the feedback activation of wild-type KRAS or other RAS isoforms induced by KRASG12Ci and greatly enhanced efficacy. In addition, TNO155 and the CDK4/6 inhibitor ribociclib showed combination benefit in a large panel of lung and colorectal cancer patient-derived xenografts, including those with KRAS mutations. Finally, TNO155 effectively inhibited RAS activation by colony-stimulating factor 1 receptor, which is critical for the maturation of immunosuppressive tumor-associated macrophages, and showed combination activity with anti-PD-1 antibody. CONCLUSIONS: Our findings suggest TNO155 is an effective agent for blocking both tumor-promoting and immune-suppressive RTK signaling in RTK- and MAPK-driven cancers and their tumor microenvironment. Our data provide the rationale for evaluating these combinations clinically.

Breast cancer cell CD200 expression regulates immune response to EMT6 tumor cells in mice.

CD200 has been characterized as an important immunoregulatory molecule, increased expression of which can lead to decreased transplant rejection, autoimmunity, and allergic disease. Elevated CD200 expression has been reported to be associated with poor prognosis in a number of human malignancies. We have found that cells of the transplantable EMT6 mouse breast cancer line growing in vitro express low levels of CD200, but levels increase markedly during growth in immunocompetent mice. Similar increased in vivo expression does not occur in NOD-SCID.IL-2(gammar-/-) mice or mice with generalized over-expression of a CD200 transgene. In both mice, tumor growth occurs faster. Altered CD200 expression in control versus transgenic mice is accompanied by reproducible changes in tumor-infiltrating host cells, and altered cell composition in lymph nodes draining the tumor (DLN). Neutralization of expressed CD200 by anti-CD200mAbs leads to decreased tumor growth in immunocompetent mice, with improved detection of cytotoxic anti-tumor immune cells in DLN. Finally, we report that tumor growth in vivo can be monitored by levels of soluble CD200 (sCD200) in serum of tumor-bearing animals.

Urinary bladder tissue engineering using natural scaffolds in a porcine model: role of Toll-like receptors and impact of biomimetic molecules.

INTRODUCTION: Natural scaffolds have been shown to induce T helper 2 (TH2)-specific immune responses in host tissues; however, the precise mechanisms that underlie this immune response are unknown. Using a porcine animal model, we evaluated the role of Toll-like receptors (TLRs) and matrix remodelling in the implantation of bladder acellular matrix (ACM) grafts and ACMs fortified with biomimetic materials. MATERIALS AND METHODS: Bladders were decellularized with detergent and treated in 3 different ways prior to implantation: ACM alone, hyaluronic acid (HA)-ACM and HA-vascular endothelial growth factor (VEGF)-ACM. Animals were sacrificed at 4 or 10 weeks post-implantation and total gene expressions for TH2 (IL-4), TH1 (IFN-γ), TLR2, TLR4, and TGF-ß1 were analyzed using real-time RT-PCR. Using histology (H&E and Masson's trichrome) and immunohistochemistry (uroplakin, α-smooth muscle actin, CD31 and factor VIII) the regenerative capacity was correlated with the gene expression of different proteins. RESULTS: IL-4, TLR2, and TLR4 gene expression were markedly decreased at 4 and 10 weeks in both the HA-ACM group and the HA-VEGF-ACM group compared to ACM alone. IFN-γ expression was negligible in all groups and time periods. TGF-ß1 expression was highest in the HA- and VEGF-treated grafts. Recellularization was inversely proportional to TLR and TH2 expression but proportional to TGF-ß1. CONCLUSION: ACM alone grafts demonstrated stronger TLR4 expression which may promote a distinct TH2 immune response and a reduced regenerative capacity in grafts. Treatment of grafts with HA and VEGF may help regulate host immune responses by reducing TLR4 and IL-4 and increasing TGF-ß1.

PPARγ Contributes to Immunity Induced by Cancer Cell Vaccines That Secrete GM-CSF.

Peroxisome proliferator activated receptor-γ (PPARγ) is a lipid-activated nuclear receptor that promotes immune tolerance through effects on macrophages, dendritic cells (DCs), and regulatory T cells (Tregs). Granulocyte-macrophage colony stimulating factor (GM-CSF) induces PPARγ expression in multiple myeloid cell types. GM-CSF contributes to both immune tolerance and protection, but the role of PPARγ in these pathways is poorly understood. Here, we reveal an unexpected stimulatory role for PPARγ in the generation of antitumor immunity with irradiated, GM-CSF-secreting tumor-cell vaccines (GVAX). Mice harboring a deletion of pparg in lysozyme M (LysM)-expressing myeloid cells (KO) showed a decreased ratio of CD8+ T effectors to Tregs and impaired tumor rejection with GVAX. Diminished tumor protection was associated with altered DC responses and increased production of the Treg attracting chemokines CCL17 and CLL22. Correspondingly, the systemic administration of PPARγ agonists to vaccinated mice elevated the CD8+ T effector to Treg ratio through effects on myeloid cells and intensified the antitumor activity of GVAX combined with cytotoxic T lymphocyte-associated antigen-4 antibody blockade. PPARγ agonists similarly attenuated Treg induction and decreased CCL17 and CCL22 levels in cultures of human peripheral blood mononuclear cells with GM-CSF-secreting tumor cells. Together, these results highlight a key role for myeloid cell PPARγ in GM-CSF-stimulated antitumor immunity and suggest that PPARγ agonists might be useful in cancer immunotherapy. Cancer Immunol Res; 6(6); 723-32. ©2018 AACR.

Mice lacking CD200R1 show absence of suppression of lipopolysaccharide-induced tumor necrosis factor-alpha and mixed leukocyte culture responses by CD200.

BACKGROUND: CD200:CD200R interactions deliver immunoregulatory signals. A family of CD200Rs (CD200R1-5) has been described, and engagement of CD200R1 by its ligand CD200 suppresses LPS-induced macrophage cytokine production, decreases alloimmune responses in vivo and in vitro, and suppresses collagen-induced arthritis. METHODS: We generated C57BL/6 mice lacking the genomic exons encoding the extracellular domains of the CD200R1 molecule using transformation of ES cells and explored cell subtypes and immune responses in these mice. RESULTS: Myeloid cells/splenocytes from CD200R1(-/-) mice were not stained in FACS by anti-CD200R1 mAb. Stimulation of splenic tumor necrosis factor-alpha production by lipopolysaccharide was enhanced relative to control (+/+) mice and was not suppressed by addition of exogenous CD200Fc. Modulation of alloreactivity in mixed leukocyte cultures by CD200Fc depended upon CD200R1+ stimulatory cells, although maximal immunoregulation by CD200Fc occurred only when CD200R1+ T responder cells also were used. CD200Fc failed to suppress graft rejection in CD200R1(-/-) mice. CONCLUSION: CD200:CD200R1 plays an immunoregulatory role in vivo.

Advances in Therapeutic Cancer Vaccines.

Therapeutic cancer vaccines aim to induce durable antitumor immunity that is capable of systemic protection against tumor recurrence or metastatic disease. Many approaches to therapeutic cancer vaccines have been explored, with varying levels of success. However, with the exception of Sipuleucel T, an ex vivo dendritic cell vaccine for prostate cancer, no therapeutic cancer vaccine has yet shown clinical efficacy in phase 3 randomized trials. Though disappointing, lessons learned from these studies have suggested new strategies to improve cancer vaccines. The clinical success of checkpoint blockade has underscored the role of peripheral tolerance mechanisms in limiting vaccine responses and highlighted the potential for combination therapies. Recent advances in transcriptome sequencing, computational modeling, and material engineering further suggest new opportunities to intensify cancer vaccines. This review will discuss the major approaches to therapeutic cancer vaccination and explore recent advances that inform the design of the next generation of cancer vaccines.

Characterization of CD200 Ectodomain Shedding.

We have previously reported the existence of a soluble form of CD200 (sCD200) in human plasma, and found sCD200 to be elevated in the plasma of Chronic Lymphocytic Leukemia (CLL) patients. CLL cells release CD200 at a constitutive level, which could be attenuated partially by ADAM28 silencing. In this study, we further explored mechanisms of CD200 shedding beyond that of ADAM28, and performed biochemical analysis of sCD200 using materials derived from purified CLL cells and Hek293 cells stably transfected with CD200, and antibodies generated specifically against either the extracellular or cytoplasmic regions of CD200. CD200 shedding was enhanced by PMA stimulation, and the loss of cell surface CD200 could be monitored as a reduction in CD200 cell surface expression by flow cytometry, in parallel with an increase in the detection of sCD200 in the supernatant. Western blot analyses and functional studies using CD200R1 expressing Hek293 cells showed that the shed CD200 detected in CLL and Hek293-hCD200 supernatants lacked the cytoplasmic domain of CD200 but retained the functional extracellular domain required for binding to, and phosphorylation of, CD200R. These data confirms that a functionally active CD200 extracellular moiety can be cleaved from the surface of CD200 expressing cells following ectodomain shedding.

Long-term Benefit of PD-L1 Blockade in Lung Cancer Associated with JAK3 Activation.

PD-1 immune checkpoint blockade occasionally results in durable clinical responses in advanced metastatic cancers. However, mechanism-based predictors of response to this immunotherapy remain incompletely characterized. We performed comprehensive genomic profiling on a tumor and germline sample from a patient with refractory lung adenocarcinoma who achieved marked long-term clinical benefit from anti-PD-L1 therapy. We discovered activating somatic and germline amino acid variants in JAK3 that promoted PD-L1 induction in lung cancer cells and in the tumor immune microenvironment. These findings suggest that genomic alterations that deregulate cytokine receptor signal transduction could contribute to PD-L1 activation and engagement of the PD-1 immune checkpoint in lung cancer.

Ectodomain shedding of CD200 from the B-CLL cell surface is regulated by ADAM28 expression.

CD200, a membrane glycoprotein of the immunoglobulin superfamily, is overexpressed in CLL. Soluble in serum CD200 (sCD200) is correlated with poor prognosis in CLL. ADAM (a disintegrin and metalloproteinase) enzymes are implicated in membrane protein shedding. ADAM28 mRNA expression in CLL was correlated with plasma sCD200 levels, and release into culture from CLL cells. siRNA for ADAM28 decreased release of sCD200 from cultures and transfection of a cloned ADAM28 gene into CD200(+) cells enhanced release of sCD200. Our data support the hypothesis that ADAM28 plays a role in the shedding of CD200 from B-cell CLL cells.

Soluble CD200 is critical to engraft chronic lymphocytic leukemia cells in immunocompromised mice.

CD200 is a transmembrane molecule with an important immunoregulatory role that is overexpressed on most chronic lymphocytic leukemia (CLL) cells. In this study, we characterized a previously unknown soluble form of this molecule in human plasma termed sCD200. Levels of sCD200 were elevated in the plasma of patients with CLL as compared with healthy controls, and there was a significant correlation with CLL disease stage. Infusion of sCD200(hi) CLL plasma into severely immunocompromised NOD.SCIDγ(c)(null) (NSG) mice enhanced the engraftment of CLL splenocytes as compared with mice receiving sCD200(lo) normal plasma. CLL cells were detected in both the spleen and peritoneal cavity of animals for up to 75 days. Engraftment of CLL cells did not occur after infusion of CLL plasma depleted of sCD200 and was abolished in mice treated with anti-CD200 or OKT3 monoclonal antibody (mAb), suggesting a role for both sCD200 and T cells in CLL engraftment. Notably, anti-CD200 mAb was as effective as rituximab in eliminating engrafted CLL cells when administered 21 days after engraftment. Taken together, our findings point to sCD200 as a novel prognostic marker and therapeutic target for CLL. Furthermore, the humanized mouse model described here may prove valuable to preclinically assess new treatment regimens for CLL.

Self-reported rates of sleep disturbance in patients with symptomatic bone metastases attending an outpatient radiotherapy clinic.

PURPOSE: To examine the reported rates and predictive factors for sleep disturbance in patients with bone metastases. METHODS: Patients with symptomatic bone metastases treated with palliative radiotherapy (RT) were eligible. At initial consultation, demographic information, baseline Brief Pain Inventory (BPI) questionnaire, and analgesic consumption were recorded. The BPI functional interference sleep item was categorized into none (0), mild (1-3), moderate (4-6), and severe (7-10). Follow-up BPI was collected in person or via telephone post-RT at week 4, 8, and 12. Subgroup analysis for BPI between responders and nonresponders was performed. Ordinal logistic regression analysis was used to search for the relationship between sleep disturbance and other covariates. RESULTS: Four hundred patients were enrolled between May 2003 and June 2007. Two hundred thirty-five males (59%) were accrued. The median age was 68 years old (range, 30-91). Within the study population, primary cancer sites included breast (25%), lung (25%), prostate (24%), bladder (4%), pancreas/gastric (3%), and other primaries (18%). In the BPI functional interference items, the mean baseline score for sleep disturbance was 4.8. When categorized in terms of severity, 99 (25%) patients had moderate sleep disturbance and 144 (36%) patients had severe sleep disturbance, respectively. There was an improvement in sleep scores for both responders and nonresponders at week 4 and 8, but scores worsened for nonresponders at week 12. CONCLUSION: Age, Karnofsky Performance Scale (KPS), pain score, and lung primary were the significant variables associated with sleep disturbance. The scores for sleep disturbance improved significantly post-RT in responders at week 4 and 12.

Tolerance mechanisms in pregnancy: a reappraisal of the role of class I paternal MHC antigens.

PROBLEM: Allogeneic pregnancies have a survival advantage over syngeneic pregnancies, and paternal Class I MHC antigens have been implicated. In humans, HLA-C and HLA-G and E are expressed by subpopulations of fetal trophoblast. In mice, Qa-2, a Class Ib antigen, and classical H-2K antigens have been described. However, the mechanism of prevention of embryo demise in utero has not been critically assessed, and a number of conflicting ideas have not been addressed. The alphabeta T-cell receptor recognizes peptide bound to the groove in Class I MHC, and peptides have profound effects on the interaction of KIR receptors on T and NK cells with Class I MHC. METHODS: Data on prevention of pregnancy loss (abortion) in poly IC-treated mice were reviewed along with information about prevention of losses in the abortion-prone CBA x DBA/2 model. This information was combined with data on paternal antigen expression at different times in pregnancy when key events determining outcome are thought to transpire, and role of tolerance signaling molecules such as CD200. Current data on models supporting a role for 'true' uterine NK cells (TuNKs) versus blood NK cells in the uterus (BuNKs) and role of MHC-KIR interaction were reviewed along with incompatible data in the literature. RESULTS: Whilst paternal Class I MHC appears important, there is an important role for paternal non-MHC minor antigens (small peptides) that bind to the antigen-presenting groove of Class I MHC. BuNKs along with CD8(+) T cells and Treg cells appear more important than TuNKs where the role of the latter appears primarily to promote angiogenesis. When during pregnancy the maternal immune system cells are first exposed to paternal Class I + peptide is uncertain, but at the time of implantation, if not earlier, seems likely. CONCLUSION: Suppression of pregnancy loss by paternal/embryo Class I MHC depends on the presence of paternal peptides. This greatly complicates existing models of Class I-KIR interactions in feto-maternal tolerance or rejection. It is important to consider all the data when devising explanatory models.

Potent immunosuppression by a bivalent molecule binding to CD200R and TGF-betaR.

BACKGROUND: The novel immunosuppressive molecule, CD200, has been reported to induce immunoregulation after interaction with its receptor(s), CD200R(s), in part at least through augmented induction of regulatory T-cell populations. Independent studies have also described increased expression of indoleamine-2,3-dioxygenase after CD200R triggering, whereas others have provided evidence that TGF-beta is important for the induction or function of many populations of regulatory T cells. We have asked whether a hybrid molecule in which a soluble fusion protein containing CD200, CD200Fc, was linked to TGF-beta through a glycine linker (Gly6) functions as a superior immunosuppressant molecule when compared with CD200Fc or TGF-beta alone, or in combination. METHODS: The hybrid molecule CD200FcGly6TGF-beta was expressed by transient transfection in CHO cells and purified over a protein A column. Functional activity of this and recombinant CD200Fc or TGF-beta alone were assessed in mixed leukocyte cultures (MLCs) and in skin graft rejection in vivo. RESULTS: Immunosuppression mediated by CD200FcGly6TGF-beta is dependent on both functional CD200 and TGF-beta moieties, as indicated by inhibition of suppression using anti-CD200 or anti-TGF-beta antibodies. Using as responder cells, using antigen-presenting cell from mice with a deletion of the CD200R gene and responder T cells from mice with siRNA-mediated suppression of expression of the TGF-betaII receptor, we show that suppression follows binding to TGF-betaRII on T cells, and CD200R1 on antigen-presenting cells. Indoleamine-2,3-dioxygenase inhibitors did not attenuate suppression by CD200FcGly6TGF-beta. CONCLUSION: CD200FcGly6TGF-beta is a potent immunosuppressant in vivo and in vitro.

The role of CD200 in immunity to B cell lymphoma.

CD200 is a transmembrane protein broadly expressed on a variety of cell types, which delivers immunoregulatory signals through binding to receptors (CD200Rs) expressed on monocytes/myeloid cells and T lymphocytes. Signals delivered through the CD200:CD200R axis have been shown to play an important role in the regulation of anti-tumor immunity, and overexpression of CD200 has been reported in a number of malignancies, including CLL, as well as on cancer stem cells. We investigated the effect of CD200 blockade in vitro on a generation of CTL responses against a poorly immunogenic CD200+ lymphoma cell line and fresh cells obtained from CLL patients using anti-CD200 mAb and CD200-specific siRNAs. Suppression of functional expression of CD200 augmented killing of the CD200+ cells, as well as production of the inflammatory cytokines IFN-gamma and TNF-alpha by effector PBMCs. Killing was mediated by CD8+ cytotoxic T cells, and CD4+ T cells play an important role in CD200-mediated suppression of CTL responses. Our data suggest that CD200 blockade may represent a novel approach to clinical treatment of CLL.

CD200-dependent and nonCD200-dependent pathways of NK cell suppression by human IVIG.

PROBLEM: Intravenous immunoglobulin (IVIG) has been used to suppress autoimmune and inflammatory disorders by a variety of mechanisms. Recently, the CD200 tolerance-promoting signal has been found to play a role in IVIG suppression of blood natural killer (NK) cells. Further, different types of IVIG have been reported to differ in this activity, and that has been related to efficacy (and inefficacy) of treatment of women with pregnancy failure. CD200 acts by binding to CD200 receptors (C200R). The objective of this study was to determine if CD200-dependent NK suppression by IVIG involved direct binding of IVIG-associated CD200 molecules to CD200R on NK cells. METHOD OF STUDY: Peripheral Blood Lymphocytes isolated from human blood were used as a source of NK cells to lyse Cr(51)-labelled K562 target cells in vitro in 18 and 4 h assays, and three different types of IVIG were tested for suppressive activity in the presence or absence of specific monoclonal anti-huCD200. In some experiments, CD56(+) NK cells were purified using anti-CD56 magnetic beads. Western blotting of IVIG using a specific anti-huCD200 antibody was done. Enzyme-Linked ImmunoSorbent Assays were used to measure cytokine production in NK assays. RESULTS: Different IVIGs showed significant differences in potency in suppressing NK cytolytic activity in vitro (mg/ml for 60% suppression, Gammagard 4.1, Gamunex 14.1, Gamimmune 20.2). For CD200-dependent suppression, Gammagard was twice as potent as Gamimmune, but equivalent to Gamunex. The presence of suppression in 4 hour assays indicated stimulation of cytokine synthesis was unlikely to explain CD200-dependent suppression. Purification of NK cells led to loss of the CD200-dependent component. Western blotting confirmed that material reactive with anti-CD200 antibody was present in Immunoglobulin G (IgG) preparations, and at a lower level in human serum that contains IgG. CONCLUSIONS: IVIGs are not all equipotent in suppressing NK cell cytolytic activity. CD200 associated with IVIG is an important component of suppression. CD200-dependent suppression appears to be mediated by a non-NK population that then acts on NK cells by direct contact rather than indirectly through release of immunosuppressive cytokines.

Motility of colon cancer cells: modulation by CD44 isoform expression.

The invasion of cancer cells at primary tumor sites and their migration during metastatic spread require the expression of cell adhesion and motility proteins. Whether accelerated cell motility is necessary in these two processes is not universally accepted. In this study we took advantage that CD44, a cell adhesion protein, has different metastatic potentials depending on its splicing isoforms to examine how they affect cell motility. We established stable transfectants of standard and variant isoforms of CD44 in SW620 cells, a human colon carcinoma cell line that does not express CD44. The morphology of the cells varied according to the CD44 isoform expressed, but actin filament distribution remained unchanged. Using the wound assay in a two-dimensional in vitro cell motility system, we found that the expression of standard CD44 increases cell motility, whereas CD44 isoforms containing an exon sequence associated with metastatic dissemination has a slowing effect. Cell proliferation was also decreased by the expression of variant CD44 isoforms. Overall, colon cancer cells expressing variant CD44 isoforms had slower cell motility, possibly due to alterations in their cell adhesion properties. In conclusion, this study suggests that, contrary to common models, the metastatic phenotype is associated with a slow rate of cell migration when tested in vitro.