Indoximod-based chemo-immunotherapy for pediatric brain tumors: A first-in-children phase I trial

BACKGROUND

Recurrent brain tumors are the leading cause of cancer death in children. Indoleamine 2,3-dioxygenase (IDO) is a targetable metabolic checkpoint that, in preclinical models, inhibits anti-tumor immunity following chemotherapy.

METHODS

We conducted a phase I trial (NCT02502708) of the oral IDO-pathway inhibitor indoximod in children with recurrent brain tumors or newly diagnosed diffuse intrinsic pontine glioma (DIPG). Separate dose-finding arms were performed for indoximod in combination with oral temozolomide (200 mg/m2/day x 5 days in 28-day cycles), or with palliative conformal radiation. Blood samples were collected at baseline and monthly for single-cell RNA-sequencing with paired single-cell T cell receptor sequencing.

RESULTS

Eighty-one patients were treated with indoximod-based combination therapy. Median follow-up was 52 months (range 39-77 months). Maximum tolerated dose was not reached, and the pediatric dose of indoximod was determined as 19.2 mg/kg/dose, twice daily. Median overall survival was 13.3 months (n = 68, range 0.2-62.7) for all patients with recurrent disease and 14.4 months (n = 13, range 4.7-29.7) for DIPG. The subset of n = 26 patients who showed evidence of objective response (even a partial or mixed response) had over 3-fold longer median OS (25.2 months, range 5.4-61.9, p = 0.006) compared to n = 37 nonresponders (7.3 months, range 0.2-62.7). Four patients remain free of active disease longer than 36 months. Single-cell sequencing confirmed emergence of new circulating CD8 T cell clonotypes with late effector phenotype.

CONCLUSIONS

Indoximod was well tolerated and could be safely combined with chemotherapy and radiation. Encouraging preliminary evidence of efficacy supports advancing to Phase II/III trials for pediatric brain tumors.

CTIM-32. FIRST-IN-CHILDREN PHASE 1 TRIAL OF INDOXIMOD-BASED CHEMO-IMMUNOTHERAPY FOR PATIENTS WITH PEDIATRIC BRAIN TUMORS: ANALYSIS OF SAFETY, TOLERABILITY, AND 5-YEAR OUTCOME

BACKGROUND

Recurrent brain tumors are the leading cause of cancer death in children. We conducted a first-in-children, two-institution, Phase 1 open-label dose-confirmation study using a 3 + 3 design, with expansion cohorts, to determine the recommended pediatric dose of the IDO pathway-inhibitor indoximod (NCT02502708). DESIGN/

METHODS

Eligible patients were 3-22 years old with either recurrent malignant brain tumor or newly-diagnosed diffuse intrinsic pontine glioma (DIPG). Palliative radiation, surgery or dexamethasone were allowed as needed for patient management. Separate dose-finding arms were performed for indoximod plus temozolomide (200 mg/m2/day orally for 5 days of each 28-day cycle) and for indoximod plus conformal radiation (in patients for whom re-irradiation was planned as standard-of-care). At progression, patients who were otherwise clinically stable were offered crossover to indoximod plus a second-line chemotherapy regimen (cyclophosphamide 2.5 mg/kg/day orally and etoposide 50 mg/m2/day orally for 21 days of each 28-day cycle).

RESULTS

Between December 2015 and January 2019, the study enrolled 81 brain tumor patients, including newly-diagnosed DIPG (n = 13) or recurrent ependymoma (n = 27), glioblastoma/high-grade glioma (n = 19), medulloblastoma (n = 13), or other CNS tumors ( n= 9). Median follow-up was 52 months (range 39-77 months). No dose-limiting toxicities were observed, and the pediatric indoximod dose was determined (19.2 mg/kg/dose, given twice daily). Indoximod was well tolerated and did not affect the ability to deliver chemotherapy or radiation as planned. Median overall survival was 13.6 months (n = 81). Median overall survival was 34.7 months for the subset of patients who continued indoximod with second-line chemotherapy after progression on indoximod plus temozolomide (n = 18).

CONCLUSIONS

Indoximod was well tolerated and could be combined with a variety of standard treatments for pediatric brain tumors. Preliminary anti-tumor activity and overall survival suggest that indoximod with standard therapy should be further evaluated in pediatric brain tumors, and potentially other pediatric solid tumors.

Effective optimization of SARS-CoV-2 laboratory testing variables in an era of supply chain constraints

RT-PCR-based assays for the detection of SARS-CoV-2 have played an essential role in the current COVID-19 pandemic. However, the sample collection and test reagents are in short supply, primarily due to supply chain issues. Thus, to eliminate testing constraints, we have optimized three key process variables: RNA extraction and RT-PCR reactions, different sample types and media to facilitate SARS-CoV-2 testing. By performing various validation and bridging studies, we have shown that various sample types such as nasopharyngeal swab, bronchioalveolar lavage and saliva, collected using conventional nasopharyngeal swabs, ESwab or 3D-printed swabs and, preserved in viral transport media, universal transport media, 0.9% sodium chloride or Amies media are compatible with RT-PCR assay for COVID-19. Besides, the reduction of PCR reagents by up to fourfold also produces reliable results.

Educational Case: Acute Promyelocytic Leukemia With PML-RARA

The following fictional case is intended as a learning tool within the Pathology Competencies for Medical Education (PCME), a set of national standards for teaching pathology. These are divided into three basic competencies: Disease Mechanisms and Processes, Organ System Pathology, and Diagnostic Medicine and Therapeutic Pathology. For additional information, and a full list of learning objectives for all three competencies, see http://journals.sagepub.com/doi/10.1177/2374289517715040.

Utility and impact of early t(15;17) identification by Fluorescence In Situ Hybridization (FISH) in clinical decision making for patients in Acute Promyelocytic Leukemia (APL)

INTRODUCTION

Acute Promyelocytic Leukemia (APL) is a curable malignancy with studies showing above 90% survival. However, population-based studies looking at survival suggest that approximately 30% of patients with APL die during induction. Early demonstration of t(15;17) will lead to accurate decision making regarding treatment. The aim of this project was to validate earlier time frames for the Abbott Molecular Vysis LSI promyelocytic leukemia (PML)/ retinoic acid receptor alpha (RARA) fluorescence in situ hybridization (FISH) probe (ASR 6-16 h).

METHODS

Twenty patients (15 APL cases and five non-APL cases) were selected for validating various hybridization times for the FISH probe. Expected normal signal pattern was two red and two green signals (2R2G), and the most common expected abnormal signal pattern was two fusion (yellow) signals, one red and one green (2F1R1G) and/or one fusion, one red and one green (1F1R1G).

RESULTS

The specificity of the probe ranged from 84% at 2 h, 86% at 4 h, 84% at 6 h, and 87% for overnight hybridization. The sensitivity increased from 79% at 2 h, 80% at 4 h, 81% at 6 h to 87% for overnight hybridization.

CONCLUSION

Based on the validation studies, we recommend reading of FISH results at the 4-h incubation mark for a preliminary diagnosis and confirmation with overnight hybridization.

RTOG 0913: A phase I study of daily everolimus (RAD001) in combination with radiation therapy and temozolomide in patients with newly diagnosed glioblastoma

2047

Background: To determine the safety of the mTOR inhibitor everolimus (RAD001) administered daily with concurrent radiation and temozolomide in newly diagnosed glioblastoma patients. Methods: Everolimus was administered daily with concurrent radiation (60 Gy in 30 fractions) and temozolomide (TMZ) (75 mg/m2/day). Everolimus was escalated from 2.5 (Dose Level 1), to 5 (Dose Level 2), to 10 mg/day (Dose Level 3). Maintenance TMZ was delivered at 150-200 mg/m2 on days 1 to 5 every 28 days for up to 12 cycles with concurrent everolimus at the previously established daily dose of 10 mg/day. Dose escalation continued if a dose level produced DLTs in ≤ 2 of the first 6 evaluable patients. Results: Between October 28, 2010 and July 2, 2012, the Radiation Therapy Oncology Group (RTOG) 0913 protocol initially registered a total of 35 patients, with 25 patients successfully meeting enrollment criteria, receiving drug and evaluable for toxicity. Everolimus was successfully escalated to the predetermined MTD of 10 mg/day. Two of the first 6 eligible patients experienced a DLT at each dose level. DLTs included: gait disturbance, febrile neutropenia, rash, fatigue, thrombocytopenia, hypoxia, ear pain, headache, and mucositis. Other common toxicities were Grade 1/2 hypercholesterolemia and hypertriglyceridemia. At the time of analysis, there was one death reported, which was attributed to tumor progression. Conclusions: Daily oral everolimus (10 mg) combined with both concurrent radiation therapy and TMZ followed by maintenance TMZ, is well tolerated, with an acceptable toxicity profile. A phase II randomized clinical trial with mandatory correlative biomarker analysis is currently underway, designed to both determine the efficacy of this regimen and identify molecular determinants of response. Supported by RTOG U10 CA21661 and CCOP U10 CA37422 grants from NCI and Novartis. Clinical trial information: NCT01062399.

Phase I trial of vorinostat combined with bevacizumab and CPT-11 in recurrent glioblastoma

A phase I study was conducted to determine the dose-limiting toxicities (DLT) and maximum tolerated dose (MTD) for the combination of vorinostat with bevacizumab and CPT-11 in recurrent glioblastoma. Vorinostat was combined with bevacizumab and CPT-11 and was escalated using a standard 3 + 3 design. Vorinostat was escalated up to 2 actively investigated doses of this compound or until the MTD was identified on the basis of DLTs. Correlative science involving proteomic profiling of serial patient plasma samples was performed. Nineteen patients were treated. The MTD of vorinostat was established at 400 mg on days 1-7 and 15-21 every 28 days when combined with bevacizumab and CPT-11. Common toxicities were fatigue and diarrhea. DLTs included fatigue, hypertension/hypotension, and central nervous system ischemia. Although the MTD was established, CPT-11 dose reductions were common early in therapy. High-dose vorinostat had an improved progression-free survival and overall survival when compared with low-dose vorinostat. Serum proteomic profiling identified IGFBP-5 and PDGF-AA as markers for improved PFS and recurrence, respectively. A MTD for the combination of vorinostat with bevacizumab and CPT-11 has been established, although it has poor long-term tolerability. With the increased toxicities associated with CPT-11 coupled with its unclear clinical significance, investigating the efficacy of vorinostat combined with bevacizumab alone may represent a more promising strategy to evaluate in the context of a phase II clinical trial.

Utility of tissue-specific transcription factors thyroid transcription factor 1 and Cdx2 in determining the primary site of metastatic adenocarcinomas to the brain

CONTEXT

Brain metastases of adenocarcinoma of unknown primary pose a diagnostic dilemma to the surgical pathologist. Although the most common source in these cases is the lung, determining a primary source is difficult on routinely stained slides. Immunohistochemical stain panels including differential cytokeratins, hormone receptors, and breast-specific proteins are commonly used in these cases. Recently, attention has turned to tissue-specific transcription factors, such as thyroid transcription factor 1 (TTF-1) and Cdx2, in the appraisal of metastatic adenocarcinomas.

OBJECTIVE

To characterize the previously unpublished immunohistochemical expression of the relatively new tissue-specific transcription factor Cdx2 in metastatic adenocarcinomas to the brain.

DESIGN

We reviewed the surgical pathology files of the H. Lee Moffitt Cancer Center and Research Institute, Tampa, Fla, and retrieved 38 consecutive cases of metastatic adenocarcinoma (22 pulmonary, 10 breast, 6 gastrointestinal [2 esophagus/gastroesophageal junction, 4 colorectal]) to the brain with confirmation of the primary site by chart review and histologic evaluation. Sections were immunohistochemically stained with antibodies to TTF-1, Cdx2, and cytokeratins 7 and 20 by standard methods.

RESULTS

Specificities and positive predictive values for Cdx2 and TTF-1 equaled 100% for metastatic gastrointestinal and pulmonary adenocarcinomas, respectively. The negative predictive value of Cdx2 was also very high at 97%.

CONCLUSIONS

Cdx2 is a specific and valuable tool for the surgical pathologist when faced with the common problem of metastatic adenocarcinoma of unknown primary. In conjunction with TTF-1, cytokeratin 7, and cytokeratin 20, Cdx2 can accurately differentiate the most common sources of metastatic adenocarcinoma to the brain.

Two cases of progressive multifocal leukoencephalopathy after allogeneic hematopoietic cell transplantation and a review of the literature

Progressive multifocal leukoencephalopathy (PML) is a rare subacute demyelinating disorder of the central nervous system (CNS) caused by the DNA JC human polyomavirus. In immunocompromised hosts, PML is caused by reactivation of a latent infection rather than de novo primary exposure. PML in the setting of hematopoietic cell transplantation (HCT) is exceedingly rare. PML should be considered in the differential diagnosis of HCT recipients, autologous or allogeneic, presenting with worsening of neurological symptoms, especially associated with post-transplant neurodegenerative findings. Although DNA polymerase chain reaction (PCR) of the cerebrospinal fluid (CSF) has emerged as a promising tool for detecting JC virus, a negative result does not rule out PML. Brain biopsy remains the most reliable and accurate method for diagnosing JC virus-associated PML. Presently, there is no universally effective antiviral therapy against JC virus and outcome is fatal in the majority of cases. We hereby describe two cases of PML developing after allogeneic HCT and provide a comprehensive review of the literature.

Passive amyloid immunotherapy clears amyloid and transiently activates microglia in a transgenic mouse model of amyloid deposition

The role of microglia in the removal of amyloid deposits after systemically administered anti-Abeta antibodies remains unclear. In the current study, we injected Tg2576 APP transgenic mice weekly with an anti-Abeta antibody for 1, 2, or 3 months such that all mice were 22 months at the end of the study. In mice immunized for 3 months, we found an improvement in alternation performance in the Y maze. Histologically, we were able to detect mouse IgG bound to congophilic amyloid deposits in those mice treated with the anti-Abeta antibody but not in those treated with a control antibody. We found that Fcgamma receptor expression on microglia was increased after 1 month of treatment, whereas CD45 was increased after 2 months of treatment. Associated with these microglial changes was a reduction in both diffuse and compact amyloid deposits after 2 months of treatment. Interestingly, the microglia markers were reduced to control levels after 3 months of treatment, whereas amyloid levels remained reduced. Serum Abeta levels and anti-Abeta antibody levels were elevated to similar levels at all three survival times in mice given anti-Abeta injections rather than control antibody injections. These data show that the antibody is able to enter the brain and bind to the amyloid deposits, likely opsonizing the Abeta and resulting in Fcgamma receptor-mediated phagocytosis. Together with our earlier work, our data argue that all proposed mechanisms of anti-Abeta antibody-mediated amyloid removal can be simultaneously active.

Cognitive impairment in PDAPP mice depends on ApoE and ACT-catalyzed amyloid formation

Biochemical and genetic studies indicate that the inflammatory proteins, apolipoprotein E (ApoE) and alpha(1)-antichymotrypsin (ACT) are important in the pathogenesis of Alzheimer's disease (AD). Using several lines of multiply transgenic/knockout mice we show here that murine ApoE and human ACT separately and synergistically facilitate both diffuse A beta immunoreactive and fibrillar amyloid deposition and thus also promote cognitive impairment in aged PDAPP(V717F) mice. The degree of cognitive impairment is highly correlated with the ApoE- and ACT-dependent hippocampal amyloid burden, with PDAPP mice lacking ApoE and ACT having little amyloid and little learning disability. A analysis of young mice before the onset of amyloid formation shows that steady-state levels of monomeric A beta peptide are unchanged by ApoE or ACT. These data suggest that the process or product of amyloid formation is more critical than monomeric A beta for the neurological decline in AD, and that the risk factors ApoE and ACT participate primarily in disease processes downstream of APP processing.

Passive immunotherapy against Abeta in aged APP-transgenic mice reverses cognitive deficits and depletes parenchymal amyloid deposits in spite of increased vascular amyloid and microhemorrhage

Background

Anti-Aβ immunotherapy in transgenic mice reduces both diffuse and compact amyloid deposits, improves memory function and clears early-stage phospho-tau aggregates. As most Alzheimer disease cases occur well past midlife, the current study examined adoptive transfer of anti-Aβ antibodies to 19- and 23-month old APP-transgenic mice.

Methods

We investigated the effects of weekly anti-Aβ antibody treatment on radial-arm water-maze performance, parenchymal and vascular amyloid loads, and the presence of microhemorrhage in the brain. 19-month-old mice were treated for 1, 2 or 3 months while 23-month-old mice were treated for 5 months. Only the 23-month-old mice were subject to radial-arm water-maze testing.

Results

After 3 months of weekly injections, this passive immunization protocol completely reversed learning and memory deficits in these mice, a benefit that was undiminished after 5 months of treatment. Dramatic reductions of diffuse Aβ immunostaining and parenchymal Congophilic amyloid deposits were observed after five months, indicating that even well-established amyloid deposits are susceptible to immunotherapy. However, cerebral amyloid angiopathy increased substantially with immunotherapy, and some deposits were associated with microhemorrhage. Reanalysis of results collected from an earlier time-course study demonstrated that these increases in vascular deposits were dependent on the duration of immunotherapy.

Conclusions

The cognitive benefits of passive immunotherapy persist in spite of the presence of vascular amyloid and small hemorrhages. These data suggest that clinical trials evaluating such treatments will require precautions to minimize potential adverse events associated with microhemorrhage.

CD40 is expressed and functional on neuronal cells

We show here that CD40 mRNA and protein are expressed by neuronal cells, and are increased in differentiated versus undifferentiated N2a and PC12 cells as measured by RT-PCR, western blotting and immunofluorescence staining. Additionally, immunohistochemistry reveals that neurons from adult mouse and human brain also express CD40 in situ. CD40 ligation results in a time-dependent increase in p44/42 MAPK activation in neuronal cells. Furthermore, ligation of CD40 opposes JNK phosphorylation and activity induced by NGF-beta removal from differentiated PC12 cells or serum withdrawal from primary cultured neurons. Importantly, CD40 ligation also protects neuronal cells from NGF-beta or serum withdrawal-induced injury and affects neuronal differentiation. Finally, adult mice deficient for the CD40 receptor demonstrate neuronal dysfunction as evidenced by decreased neurofilament isoforms, reduced Bcl-x(L):Bax ratio, neuronal morphological change, increased DNA fragmentation, and gross brain abnormality. These changes occur with age, and are clearly evident at 16 months. Taken together, these data demonstrate a role of CD40 in neuronal development, maintenance and protection in vitro and in vivo.

MMP-2 and TIMP-1 are derived from, not in response to, pancreatic cancer

INTRODUCTION

Genetic therapy aimed at disturbing the balance between matrix metalloproteinases (MMP) and their natural tissue inhibitors (TIMP) in treatment of pancreatic cancer requires an understanding of whether MMP and TIMP are tumor- or host-derived. This study was undertaken to determine whether production of MMP-2 and TIMP-1 is by, or in response to, pancreatic cancer.

METHODS

PANC-1 (poorly differentiated human pancreatic cancer) or CD-1 (PANC cells transfected to overproduce TIMP-1) cells were implanted into the pancreata of 20 nude mice. After sacrifice, tumors and peritumoral stroma underwent immunohistochemical staining for human and murine MMP-2 and TIMP-1. Normal murine pancreas served as control. All stains were reviewed in a "blinded" manner by a pathologist and graded relative to normal control pancreata.

RESULTS

Control pancreata displayed faint murine MMP-2 and TIMP-1 staining and no human MMP-2 or TIMP-1. MMP-2 was most prominent in peritumoral stroma, while TIMP-1 was most prominent in tumors. CD-1 tumors contained very high levels of TIMP-1 compared to PANC-1 tumors and control pancreata. Tumoral and peritumoral MMP-2 were overwhelmingly human. As well, tumoral TIMP-1 was predominantly human.

CONCLUSIONS

In a murine model for human pancreatic cancer, nearly all TIMP-1 and MMP-2 expression is tumor-derived (i.e., human). Pharmacologic and gene therapy aimed at disturbing the MMP/TIMP balance in pancreatic cancer should be targeted toward tumor-specific mechanisms and warrants continued investigation.

Classification of sporadic Creutzfeldt-Jakob disease based on molecular and phenotypic analysis of 300 subjects

Phenotypic heterogeneity in sporadic Creutzfeldt-Jakob disease (sCJD) is well documented, but there is not yet a systematic classification of the disease variants. In a previous study, we showed that the polymorphic codon 129 of the prion protein gene (PRNP), and two types of protease-resistant prion protein (PrP(Sc)) with distinct physicochemical properties, are major determinants of these variants. To define the full spectrum of variants, we have examined a series of 300 sCJD patients. Clinical features, PRNP genotype, and PrP(Sc) properties were determined in all subjects. In 187, we also studied neuropathological features and immunohistochemical pattern of PrP(Sc) deposition. Seventy percent of subjects showed the classic CJD phenotype, PrP(Sc) type 1, and at least one methionine allele at codon 129; 25% of cases displayed the ataxic and kuru-plaque variants, associated to PrP(Sc) type 2, and valine homozygosity or heterozygosity at codon 129, respectively. Two additional variants, which included a thalamic form of CJD and a phenotype characterized by prominent dementia and cortical pathology, were linked to PrP(Sc) type 2 and methionine homozygosity. Finally, a rare phenotype characterized by progressive dementia was linked to PrP(Sc) type 1 and valine homozygosity. The present data demonstrate the existence of six phenotypic variants of sCJD. The physicochemical properties of PrP(Sc) in conjunction with the PRNP codon 129 genotype largely determine this phenotypic variability, and allow a molecular classification of the disease variants.

Targeting the tumor vasculature with combretastatin A-4 disodium phosphate: effects on radiation therapy

PURPOSE

The aim of this study was to evaluate the antitumor efficacy of combretastatin A-4 disodium phosphate (combretastatin prodrug) in the rodent KHT sarcoma model either alone or in combination with radiation therapy.

METHODS

KHT tumors were grown in C3H/HeJ mice. Combretastatin A-4 prodrug was injected intraperitoneally at doses ranging from 10 to 100 mg/kg. Tumors were irradiated in unanesthetized mice using a 137Cs source. Tumor response to combretastatin A-4 prodrug was assessed by histological evaluations as well as an in vivo to in vitro cell survival assay.

RESULTS

Histological evaluation showed morphological damage of tumor cells within a few hours after drug treatment, followed by extensive central necrosis. Administering increasing doses of combretastatin A-4 prodrug to tumor-bearing mice resulted in a dose-dependent increase in cell killing irrespective of whether the tumors were irradiated or not. When combined with radiation, a 100 mg/kg dose of combretastatin A-4 prodrug reduced tumor cell survival 10-500-fold lower than that seen with radiation alone. Further, the shape of the cell survival curve observed following the combination therapy suggested that including combretastatin in the treatment had a major effect on the radiation-resistant hypoxic cell subpopulation associated with this tumor.

CONCLUSION

The present results demonstrated that in the KHT sarcoma, combretastatin A-4 prodrug caused rapid vascular shutdown, a concentration-dependent direct cell killing, and effective enhancement of the antitumor effects of radiation therapy.

Facial palsy from Masson's vegetant intravascular hemangioendothelioma

Masson's vegetant intravascular hemangioendothelioma (VIH) is a rare benign tumor that has a propensity for the head and neck but has been overlooked in the otolaryngology literature. Herein, we present the first report of facial palsy resulting from a small VIH growing in the fundus of the internal auditory canal and the labyrinthine segment of the fallopian canal.

Facial Palsy from Masson's Vegetant Intravascular Hemangioendothelioma

Masson's vegetant intravascular hemangioendothelioma (VIH) is a rare benign tumor that has a propensity for the head and neck but has been overlooked in the otolaryngology literature. Herein, we present the first report of facial palsy resulting from a small VIH growing in the fundus of the internal auditory canal and the labyrinthine segment of the fallopian canal.

A 66-year-old woman with a rapidly progressing dementia and basal ganglia involvement

A 66-year-old woman presented with a rapidly progressive dementia initially characterized by an auditory agnosia. She experienced a rapid progression of her aphasia and developed ataxia and myoclonus. An initial neurological evaluation suggested a left parieto-temporal lesion, however, neuroimaging did not reveal any. An MRI of her brain demonstrated highly focal T2 hyperintensities in her basal ganglia. The patient was diagnosed with Creutzfeldt-Jacob Disease (CJD) on the basis of the presence of two proteins in the CSF that are highly sensitive and specific for CJD. Pathological examination confirmed the diagnosis. The differential diagnosis and utility of MRI in patients with CJD is discussed.

Assessment of laminin-mediated glioma invasion in vitro and by glioma tumors engrafted within rat spinal cord

Cell motility within central nervous system (CNS) neuropil may be largely restricted yet infiltration by glioma cells is commonly observed. Glioma cells remodel nervous tissue and may assemble extracellular matrix in order to migrate. We examined the rat C6 glioma cell line for laminin expression and response in vitro and following engraftment into rat spinal cord. C6 cell cultures expressed laminin-2. C6 cells attached equally well to substrates of purified laminin-1 and laminin-2 and laminin-2-enriched C6 conditioned medium. In contrast, C6 cell migration was substantially greater on laminin-2 and C6-derived substrata than on laminin-1. Glioma cell attachment to laminin-1 and -2 was largely inhibited by antibody to the laminin receptor LBP110 and by an IKVAV peptide but not by YIGSR or control peptides. IKVAV peptide and anti-LBP110 antibodies also inhibited glioma cell invasion through synthetic basement membrane. Anti-beta 1 integrin antibody selectively inhibited cell migration and invasion on laminin-2 substrata without affecting percent cell attachment. These findings suggest C6 cell migration and invasion are promoted by autocrine release of laminin-2 and involve LPB110 and beta 1 integrin laminin receptors. A possible role for laminin-2 in CNS infiltration in vivo was examined following glioma engraftment into rat spinal cord. Engrafted C6 tumors share many histologic features of invasive human glioma. Engrafted glioma cells expressed laminin, LBP110 and beta 1 integrin antigens, indicating the molecular mechanisms of C6 motility observed in culture may contribute to glioma invasion in vivo. NMR and corroborative immunocytochemistry provided precise means to monitor tumor progression following glioma engraftment into rat spinal cord. Advantages of this glioma model are discussed regarding the assessment of anti-adhesive therapies in vivo.