Osimertinib treatment for patients with EGFR exon 20 mutation positive non-small cell lung cancer

OBJECTIVES

Epidermal growth factor receptor (EGFR) exon 20 insertions comprise 4-10 % of EGFR mutations in non-small cell lung cancer (NSCLC) and are associated with primary resistance to first and second generation EGFR tyrosine kinase inhibitors (TKIs). In vitro and preclinical animal studies have shown that osimertinib exerts antitumor activity against EGFR exon 20 mutation positive NSCLC. We report on a cohort of advanced stage NSCLC patients who harbor an EGFR exon 20 mutation and received osimertinib treatment.

MATERIAL AND METHODS

Twenty-one patients were treated with osimertinib 80 or 160 mg once daily from April 2016 to June 2018, in four institutions in the Netherlands. Data were obtained retrospectively. Progression free survival (PFS), disease control rate (DCR), overall survival (OS) and objective response rate (ORR) were assessed using RECIST v1.1.

RESULTS

Thirteen patients received prior platinum-based chemotherapy, and three patients a first - or second generation EGFR TKI. We observed 1 partial response, 17 patients with stable disease and 3 with progressive disease as best response to osimertinib (ORR 5 %). Median PFS was 3.6 (95 % CI, 2.6-4.5) months. PFS did not differ for patients with co-occurring TP53 mutations (p = 0.937). The DCR at three months was 71 %. Median OS was 8.7 (95 % CI, 1.1-16.4) months.

CONCLUSION

Osimertinib has limited antitumor activity in patients with EGFR exon 20 mutated NSCLC, with an ORR of 5 %.

A phase II study of bevacizumab and erlotinib after radiation and temozolomide in MGMT unmethylated GBM patients

Survival for glioblastoma (GBM) patients with an unmethyated MGMT promoter in their tumor is generally worse than methylated MGMT tumors, as temozolomide (TMZ) response is limited. How to better treat patients with unmethylated MGMT is unknown. We performed a trial combining erlotinib and bevacizumab in unmethylated GBM patients after completion of radiation (RT) and TMZ. GBM patients with an unmethylated MGMT promoter were trial eligible. Patient received standard RT (60 Gy) and TMZ (75 mg/m2 × 6 weeks) after surgical resection of their tumor. After completion of RT they started erlotinib 150 mg daily and bevacizumab 10 mg/kg every 2 weeks until progression. Imaging evaluations occurred every 8 weeks. The primary endpoint was overall survival. Of the 48 unmethylated patients enrolled, 46 were evaluable (29 men and 17 women); median age was 55.5 years (29-75) and median KPS was 90 (70-100). All patients completed RT with TMZ. The median number of cycles (1 cycle was 4 weeks) was 8 (2-47). Forty-one patients either progressed or died with a median progression free survival of 9.2 months. At a follow up of 33 months the median overall survival was 13.2 months. There were no unexpected toxicities and most observed toxicities were categorized as CTC grade 1 or 2. The combination of erlotinib and bevacizumab is tolerable but did not meet our primary endpoint of increasing survival. Importantly, more trials are needed to find better therapies for GBM patients with an unmethylated MGMT promoter.

Somatic SF3B1 mutation in myelodysplasia with ring sideroblasts

BACKGROUND

Myelodysplastic syndromes are a diverse and common group of chronic hematologic cancers. The identification of new genetic lesions could facilitate new diagnostic and therapeutic strategies.

METHODS

We used massively parallel sequencing technology to identify somatically acquired point mutations across all protein-coding exons in the genome in 9 patients with low-grade myelodysplasia. Targeted resequencing of the gene encoding RNA splicing factor 3B, subunit 1 (SF3B1), was also performed in a cohort of 2087 patients with myeloid or other cancers.

RESULTS

We identified 64 point mutations in the 9 patients. Recurrent somatically acquired mutations were identified in SF3B1. Follow-up revealed SF3B1 mutations in 72 of 354 patients (20%) with myelodysplastic syndromes, with particularly high frequency among patients whose disease was characterized by ring sideroblasts (53 of 82 [65%]). The gene was also mutated in 1 to 5% of patients with a variety of other tumor types. The observed mutations were less deleterious than was expected on the basis of chance, suggesting that the mutated protein retains structural integrity with altered function. SF3B1 mutations were associated with down-regulation of key gene networks, including core mitochondrial pathways. Clinically, patients with SF3B1 mutations had fewer cytopenias and longer event-free survival than patients without SF3B1 mutations.

CONCLUSIONS

Mutations in SF3B1 implicate abnormalities of messenger RNA splicing in the pathogenesis of myelodysplastic syndromes. (Funded by the Wellcome Trust and others.).

Best Practice Guidelines for use of OSCEs: Maximising value for student learning

Objective structured clinical examinations (OSCEs) are a regular component of Bachelor of Nursing (BN) programs within Australia and internationally. OSCEs are a valuable strategy to assess 'fitness to practice' at the students' expected level of clinical practice within a nursing context where the importance of accurate patient assessment is paramount. This report discusses the integration of seven proposed 'Best Practice Guidelines' (BPG) into an undergraduate BN program in Queensland, Australia. A range of learning and assessment strategies was introduced in accordance with the adoption of these guidelines to maximise student engagement. There is some evidence that these strategies have directly assisted in enhanced student confidence around clinical practice and provide preliminary evidence of the effectiveness of BPG for OSCEs within nursing programs internationally.

Neuronal and glial cerebrospinal fluid protein biomarkers are elevated after West Nile virus infection

Neurotrophic West Nile virus (WNV) disease is a severe arbovirus infection in which neuronal loss is the likely anatomical substrate for the high morbidity and mortality. We investigated whether cerebrospinal fluid (CSF) protein biomarkers were elevated in vivo and related to disease severity in patients with WNV infection. This exploratory study included 114 patients (24 acute WNV, 77 noninflammatory controls, six peripheral neuropathies, seven aseptic meningoencephalitis). CSF levels of neuronal (neurofilaments, NfH-SMI35) and glial (glial fibrillary acidic protein, GFAP, S100B) biomarkers were measured by enzyme-linked immunosorbent assay (ELISA). Immunocytochemistry was performed in two fatal WNV cases. A significant proportion of patients with WNV had pathological CSF levels for NfH-SMI35 (58%, median concentration 1.01 ng/mL), GFAP (58%, 10 pg/mL), and S100B (90%, 1.29 ng/mL). The results were consistent with postmortem evidence for neuronal death and astrogliosis. Surprisingly, CSF protein biomarker levels were also found to be pathological in a considerable proportion of patients who presented with WNV fever only (100% for GFAP and S100B and 43% for NfH-SMI35). Elevated CSF protein biomarker levels are suggestive of neuronal death and glial pathology in human WNV infection. The results indicate the presence of neuroinvasive disease across the spectrum of WNV disease, including WNV fever.

RTOG 0625: A phase II study of bevacizumab with irinotecan in recurrent glioblastoma (GBM)

2011

Background: Angiogenesis is a hallmark of GBM, making the tumor vasculature an attractive therapeutic target. In gliomas, vascular endothelial growth factor (VEGF) promotes both angiogenesis and invasion of tumor cells. Bevacizumab is a humanized monoclonal antibody against VEGF-A that rapidly reduces the concentration of VEGF in the circulation. Irinotecan may enhance efficacy by synergistic tumor endothelial cell death or improved tumor delivery of the chemotherapy via “normalized” tumor vasculature. Prior studies of this combination demonstrated high radiographic response and 6-month progression free (6-mPFS) rates. This study was designed to determine the efficacy and safety of this regimen in the cooperative group setting. Methods: Eligibility included age ≥ 18, centrally confirmed GBM or gliosarcoma, progressive or recurrent disease. Enzyme-inducing anticonvulsants were not allowed. Treatment was intravenous bevacizumab 10 mg/kg and irinotecan 200 mg/m2 every 2 weeks. Accrual goal was 57 eligible patients. Primary endpoint was 6-mPFS rate where an estimate of ≥ 35% would define efficacy (15% improvement over historical data). Results: Full enrollment (57) was achieved, median age was 57, median KPS was 80; all had prior radiation and temozolomide treatment. The 6m-PFS rate was 37% (95% CI: 24–50%), with 21 of 57 patients progression-free at 6 months. Moderate toxicity was noted with 21(37%) grade 3, seven (12%) grade 4, and one (<2%) treatment-related death (intracranial hemorrhage). There were six episodes of venous thrombosis, 14 episodes of grade 3 or 4 hematologic toxicity, predominantly lymphopenia (7), and neutropenia (4), no opportunistic infections or febrile neutropenia were noted. Other toxicities included fatigue (9), diarrhea (2), and hypertension (2). Conclusions: These results, in the cooperative group context, corroborate the efficacy of the bevacizumab and irinotecan combination for recurrent GBM with the 6m-PFS surpassing the predetermined efficacy threshold. Previously described toxicities were confirmed with a moderately high rate of venous thrombosis, one intracranial hemorrhage, and moderate hypertension. Studies to determine the contribution of the cytotoxic agent to efficacy and the role of bevacizumab in newly diagnosed GBM are planned.

[Table: see text]

Autoimmune pancytopenia following combination chemotherapy for chronic lymphocytic leukaemia: Figure 1

Autoimmune haemolysis or thrombocytopenia can complicate purine nucleoside monotherapy for chronic lymphocytic leukaemia (CLL), but Evans syndrome is rare. This is a report of the occurrence of pancytopenia secondary to a unique combination of red cell aplasia with autoimmune thrombocytopenia and neutropenia in a patient with CLL following treatment with fludarabine and cyclophosphamide. This case is unusual for the simultaneous targeting of three haemopoietic lineages by immune dysfunction following fludarabine and cyclophosphamide, which is a treatment regimen believed to reduce autoimmune haematological toxicity in CLL.

The use of nerve and muscle biopsy in the diagnosis of vasculitis: a 5 year retrospective study

INTRODUCTION

Peripheral nerve vasculitis is an important condition which can be diagnostically challenging and is one of the principal current indications for nerve and muscle biopsy. Previous studies have suggested that combined nerve and muscle biopsy (usually of the superficial peroneal nerve and peroneus brevis muscle) produces a higher diagnostic yield than nerve biopsy alone in the investigation of vasculitis.

OBJECTIVE

To determine whether in our two centres combined nerve (usually the sural) and muscle (usually the vastus lateralis) biopsy improved diagnostic yield compared with nerve biopsy alone.

METHODS

We interrogated our database of all nerve biopsies (usually of the sural nerve) performed at our institutions over 5 years and identified 53 cases of biopsy proven peripheral nerve vasculitis. Clinicopathological and neurophysiological data in these patients were reviewed.

RESULTS

The most common clinical presentation was with a painful asymmetric axonal polyneuropathy or mononeuritis multiplex (66% of cases). Nerve biopsy demonstrated definite vasculitis in 36%, probable vasculitis in 62% and no vasculitis in 2% of cases. In 24 patients a muscle biopsy (usually the vastus lateralis) was also performed and vasculitis was demonstrated in 46% of these (in 13% showing definite and 33% probable vasculitis). There was only one patient in whom vasculitis was demonstrated in muscle but not in peripheral nerve.

CONCLUSION

Combined nerve (usually sural) and vastus lateralis muscle biopsy did not significantly increase the diagnostic yield compared with nerve biopsy alone. A sensible approach to the diagnosis of peripheral nerve vasculitis is to choose a nerve to biopsy which is clinically affected and amenable to biopsy. If the sural nerve is chosen, the data suggest that it is not routinely worth doing a vastus lateralis biopsy at the same time, whereas if the superficial peroneal nerve is chosen, it seems appropriate to do a combined superficial peroneal nerve and peroneus brevis biopsy. It is still not known if both the sural and superficial peroneal nerves are involved clinically which one gives the higher yield if biopsied.

A case study of mixed cryoglobulinaemia associated with peripheral neuropathy

The clinical diagnosis of mixed cryoglobulinaemia is difficult due to heterogeneity in presentation. Symptoms include the classical triad of purpura, arthralgia and weakness, with one or more other organs involved. We discuss a case of cryoglobulinaemia that presented with sensory motor neuropathy and with features of mononeuritis multiplex syndrome, but which lacked other classical features. Laboratory testing revealed a profile typical of mixed cryoglobulins: immunoglobulin M (IgM) paraprotein, low fourth carbon (C4) and positive rheumatoid factor. Subsequent investigations failed to reveal an underlying infectious or neoplastic cause. This case demonstrates the need to include cryoglobulinaemia in the differential diagnosis for peripheral neuropathy, and the critical importance of using the correct collection procedure to isolate cryoglobulins.

Diverse humoral autoimmunity to the ribosomal P proteins in systemic lupus erythematosus and hepatitis C virus infection

Autoantibodies to the three ribosomal P proteins (Rib-P) are specifically found in 10% to 40% of systemic lupus erythematosus (SLE) patients. Most anti-Rib-P autoantibodies bind to a C-terminal epitope shared by all three Rib-P proteins P0, P1 and P2. In the present study, we shed more light on the humoral autoimmune response to the Rib-P antigen as it occurs in autoimmunity and infectious disease. In a mutational analysis of the major C-terminal epitope, we verified the key role of phenylalanine residues Phe ( 111 ) and Phe ( 114 ) for binding of most anti-Rib-P serum autoantibodies present in SLE sera (n = 28). By nuclear magnetic resonance (NMR) investigation of a peptide comprising the C-terminal 22 amino acids, we observed hallmarks for alpha-helical secondary structure of the Rib-P epitope core (GFGLFD). Based on NMR data and on SPOT epitope analysis, we propose a structural model of the Rib-P major epitope, which displays Phe ( 111 ) and Phe ( 114 ) on one side of the helix. Apart from that, two sera from the hepatitis C virus (HCV) control group (n = 68) were found to contain antibodies specific for P2, but not for the other Rib-P proteins. Using a SPOT peptide array scanning the P2 amino acid sequence, we identified reactivity with two distinct epitopes (residues 21-35 and 41-55 of Rib-P2) shared by both HCV sera. We conclude that anti-Rib-P autoreactivity occurs in SLE, Chagas' disease (CD) and-as firstly described here-during HCV infection. Anti-Rib-P reactivity in SLE sera primarily depends on Phe ( 111 ) and Phe ( 114 ) of the alpha-helical C-terminal epitope. In contrast, anti-Rib-P autoantibodies in HCV infection mainly recognize epitopes within the N-terminal half of ribosomal P2.

Final results of a phase I trial with the novel anthracycline derivative RTA 744 in patients with primary brain tumors

2062

Background: RTA 744 is an anthracycline derivative that was shown preclinically to cross the blood-brain barrier, not be a substrate for P-gp or MRP, and improve survival in an orthotopic murine model of glioblastoma. A trial of RTA 744 was conducted in patients with progressive high-grade gliomas. Methods: RTA 744 was administered as a 2-hour intravenous infusion on each of the first 3 days of a 21-day cycle. Five dose levels were tested until an MTD was reached. Pharmacokinetic samples were taken at multiple time points on days 1–5 of cycle 1. Tumor activity was assessed according to the MacDonald criteria. Results: As of December 2006, RTA 744 has been administered to 20 patients at doses ranging from 1.2 to 9.6 mg/m2/day. The MTD was determined as 7.5 mg/m2/day, and the DLTs were neutropenia and thrombocytopenia. No neurotoxicity, cardiotoxicity, alopecia, or drug-related nausea and vomiting were reported. The pharmacokinetic profile indicates dose proportionality, with a mean plasma half-life of 35 hours. Clear evidence of anti-tumor activity has been reported in 7 of 20 patients. A Complete Response was observed in a patient with GBM after seven cycles at 2.4 mg/m2/day, the patient continues greater than 5 months post-RTA744 treatment. Additionally, a Partial Response (81% tumor reduction) has been observed in a patient with AO after two cycles at 7.5 mg/m2/day who continues on treatment at this time. A Minor Response was observed at 2.4 mg/m2/day, and several patients have experienced Stable Disease of several months duration. Two patients with stable disease have shown radiographic evidence of necrosis. Median time to tumor progression was 6 weeks (range 2 to >50). Median number of cycles was 2 (range 1 to 7). The study is now enrolling additional patients at the MTD to further profile the drug’s safety and activity. Additionally, a once-weekly dosing schedule is being tested in a satellite cohort. Conclusions: RTA 744 is well tolerated when administered at doses up to and including 7.5 mg/m2/day for the first three days of a 21-day cycle. Based on clear evidence of drug activity, pivotal trials of RTA 744 in high-grade gliomas are planned as well as trials in patients with brain metastases.

[Table: see text]

Phase II study of combination carboplatin and erlotinib in patients with recurrent glioblastoma multiforme

2024

Background: Targeting the epidermal growth factor receptor (EGFR) in glioblastoma is effective in a subset of patients whose tumors express the phosphatase and tensin homolog (PTEN) tumor suppressor gene and overexpress the EGF variant vIII receptor. Therefore, this study was designed to assess the clinical activity of the EGFR inhibitor erlotinib when combined with carboplatin and to determine molecular predictors of response. The primary endpoint is progression-free survival (PFS). To be eligible for the study, patients had to have recurrent, histologically confirmed glioblastoma or gliosarcoma, no more than two prior relapses, a KPS = 60, and no enzyme-inducing anticonvulsants. Methods: In this ongoing phase II study, patients are given carboplatin intravenously on day 1 of every 28-day cycle to achieve a target AUC of 6 (mg x ml/min) based on creatinine clearance. Erlotinib is administered orally once daily throughout the 28-day cycle at 150 mg/day with dose escalation to 200 mg/day, as tolerated. Patients undergo clinical and MRI assessment every 4 weeks. The primary endpoint is median PFS using a Bayesian time-to-event design. To determine histologic correlates of response, tumor tissue is undergoing immunohistochemical evaluation for known markers of response to EGFR inhibitors, including PI3K/AKT and PTEN status. Results: Of the first 20 patients enrolled, 17 were evaluable and all had failed temozolomide-based therapy. The median age is 56 years, and the median KPS is 80. The median time to progression is 15.2 weeks with a 95% credible interval of 8.0 to 28.4 weeks. These results compare favorably with historical data (median of 9.0 weeks, 95% CI of 8.1 to 10.1 weeks). Bayesian analysis using computer-based simulations indicate a high probability (69%) that the median PFS in our study is at least 3 weeks longer than the historical median PFS. Grade 3 and 4 toxicities included fatigue, leukopenia, thrombocytopenia and rash requiring dose reductions. Conclusions: The results from this ongoing study suggest that the combination of carboplatin and erlotinib has promising activity in patients with recurrent glioblastoma who have failed temozolomide-based therapy. Tumor tissue is being analyzed to determine molecular markers of response.

[Table: see text]

Primary sciatic nerve lymphoma: a case report and review of the literature

A patient with primary B cell non-Hodgkin's lymphoma of the sciatic nerve is described. He presented with neuropathic symptoms in the left leg, initially diagnosed as tarsal tunnel syndrome. Magnetic resonance imaging (MRI) identified the abnormality in the sciatic nerve. A fascicular biopsy of the sciatic nerve showed a diffuse large B cell non-Hodgkin's lymphoma. The patient was treated with chemotherapy and rituximab (anti-CD20 monoclonal antibody). Four months later he was in remission, and remains so 48 months from presentation. Primary lymphoma of single peripheral nerves may be a unique subtype of extranodal lymphoma, which usually follows an aggressive course and has a variable response to current therapeutic strategies. MRI is useful, alongside electrophysiological studies, in patients with atypical peripheral nerve symptoms.

Toxicity and efficacy profiles of intrathecal injection of I-131 NaI via intraventricular (IVent) or intralumbar (Ilumb) route for leptomeningeal metastases (LM) therapy

1549

Background: LM is a fatal complication occurring in up to 30% of cancer patients. Intrathecal chemotherapy of LM is limited by diffusion while external beam irradiation is limited by neurotoxicity. Radioiodine I-131 may serve as a ablating agent because of its radiations transverse the meningeal thinkness but spare distant underlying nervous tissues. Two phase I studies are designed to determine MTD and to evaluate potential toxicity and efficacy of intrathecal I-131 sodium iodide (NaI) injected via IVent or the ILumb route. Methods: The IVent or Ilumb protocols each accured 5 groups of patients with cytology-confirmed LM from solid tumors. An injection of 15, 30, 60, 90 or 120 mCi of I-131 NaI was performed after thyroid blockade (Lugol solution and perchlorate), via an Ommaya reservoir (IVent) or lumbar puncture (ILumb). Patients underwent whole-body scintigraphy for biodistribution and radiation dosimetry. Follow-up studies consisted of serial CSF cytology, neuropsychology, ophthalmology, and serum tests (TSH and CBC) to 6 months. Results: The IVent and Ilumb studies accured 16 and 15 patients respectively with LM from melanoma, lung, breast and other tumors (13, 8, 6 and 4 of 31 patients). Because of re-entry into the protocols, one patient received a total of 407 mCi; the maximum radiation absorbed doses were estimated at 3716 cGy in the ventricular CSF and 54 cGy in the red marrow. No treatment-related NCI-Grade II/III/IV neurologic, hematologic or thyroid toxicity is noted. Transient improvements up to 6 weeks are noted in neuropsychologic tests (5/16 and 5/15), ophthalomologic test (3/16 and 1/15) and CSF cytology conversion (to negative) in 5/16 and 4/15 patients, respectively. Electrophysiology tests of 2 patients demonstrated normalization of P37 waves measured by somatosensory evoked potentials along with neuropsychologic test improvements. Conclusions: The MTD has not been reached up to 120 mCi on either the IVent or Ilumb protocol. Intrathecal I-131 NaI is likely to be efficacious to eradicate tumors in the CSF for LM therapy. Because of the low toxicity and likely efficacy, a phase II study with higher dosages is needed to fully explore therapeutic potentials of intrathecal I-131 NaI.

No significant financial relationships to disclose.

A phase I study of temozolomide (TMZ) and the farnesyltransferase inhibitor (FTI), lonafarnib (Sarazar, SCH66336) in recurrent glioblastoma

1556

Background: Farnesylation is essential for the post-translational modification of several proteins that play a role in cell proliferation and growth. FTIs demonstrate antiproliferative effects in a variety of tumor cell lines and xenograft models and enhanced efficacy by combining lonafarnib with TMZ compared with TMZ alone. Clinical studies show that dose-intense TMZ may have better efficacy then conventional dosing (Wick, Neurology 2004). Objective: Determine the maximum tolerated dose of lonafarnib when combined with a dose-intensified schedule of TMZ. Eligibility criteria: Histologically proven GBM; evidence of relaspe or progression; up to 2 prior chemotherapy regimens, prior TMZ permitted; KPS ≥ 60. No enzyme-inducing anticonvulsants. Methods: TMZ was given at 150 mg/m2 days 1–7 and 15–21; lonafarnib escalated by cohort: 100 mg BID, 150 mg BID, 200 mg BID on days 8–14 and 22–28 of a 28-day cycle. Response: Toxicity measured after cycle 1 using NCI CTCAE v3. Patient (pt)accrual used a 3 + 3 design. Response was evaluated q2 cycles. Standard response criteria (MacDonald) were used. Results: 15 patients were accrued. Median age 47 yrs; median KPS 90. M:F ratio was 11:4. No DLTs in any dose cohort, a pt (cohort 1) died day 29 of unrelated cardiac disease. 4 pts demonstrated partial response, all with prior TMZ failure, 3 pts showed prolonged stable disease. 6-month PFS rate estimated at 33%, median PFS 14 weeks. Treatment was well tolerated: 1 episode each of grade 3 diarrhea, esophagitis, fatigue and hypokalemia; 3 episodes of grade 3/4 leukopenia, 2 episodes of grade 3/4 neutropenia, and 2 episodes of grade 4 thrombocytopenia. Seven pts had grade 3/4 lymphopenia, some with persistant lymphopenia from prior TMZ. 1 pt had grade 4 pneumonitis of uncertain etiology. Conclusions: The alternating week schedule of TMZ/lonafarnib was well tolerated. Preliminary results suggest anti-tumor activity even in pts who had failed prior TMZ. It is not certain whether this activity is due to the dose-intensified TMZ or the treatment combination. Studies are planned to evaluate potential predictors of response (i.e MGMT gene promoter methylation) and expand the trial to obtain pharmacokinetic and additional efficacy data.

[Table: see text]

The neuropathology of paraneoplastic syndromes

The term "paraneoplastic neurological syndromes" encompasses a number of uncommon disorders associated with systemic malignancies. In order to be classified a paraneoplastic neurological syndrome, the malignancies must not invade, compress, or metastasize to the nervous system. They can either focally or diffusely involve the central and peripheral nervous system or the neuromuscular junction. This paper reviews the neuropathology of the syndrome. It will first describe the clinical presentation and give an account of the systemic tumors most commonly associated with the various types of disorders. Then it will review the general pathological features that consist of an inflammatory process predominantly affecting the gray matter. Finally, it will describe in detail the main clinico-pathological types, including 1) encephalomyelitis, 2) cortical cerebellar degeneration, 3) peripheral neuropathy, 4) opsoclonus-myoclonus and 5) retinopathy. The Lambert-Eaton myasthenic syndrome will be dealt with separately in another paper in this symposium.

Expression of CCR-5/CXCR-4 in spinal cord of patients with AIDS

The discovery that chemokines and their receptors (in particular CXCR-4 and CCR-5) play a role in HIV infection challenges traditional views on the pathogenesis of HIV infection in man and identifies new potential targets for therapeutic intervention. Several groups as well as our pilot study have found that increased numbers of CCR-5 positive macrophage/microglia correlate with disease severity in brains of patients with AIDS. Among HIV-related disorders, vacuolar myelopathy (VM) is the most common spinal cord disorder in patients with AIDS. The purpose of this study was to investigate the possible relationship between the expression of CCR-5/CXCR-4 and spinal cord pathology in patients with AIDS. Thirty-four spinal cords (forming two groups: without and with VM) of patients with AIDS and 6 HIV-1-negative controls were investigated by routine histological examination and immunohistochemistry. Elevated expression of CXCR-4 was found in most AIDS cases with/without neuropathological disorders (8/17 and 13/16, respectively). No CCR-5 expression was detected in HIV-1-negative controls. Among 34 cases with AIDS, expression of CCR-5 was detected in 1/16 HIV-1-positive normal spinal cords and 5/18 with VM. Despite the lack of statistical significance between the two groups (P=0.1019), our results suggest that CCR-5/CXCR-4 are present in spinal cord of patients with AIDS and that CCR-5 is more frequently found in association with VM.

Healthcare, molecular tools and applied genome research

Biotechnology 2000 offered a rare opportunity for scientists from academia and industry to present and discuss data in fields as diverse as environmental biotechnology and applied genome research. The healthcare section of the meeting encompassed a number of gene therapy delivery systems that are successfully treating genetic disorders. Beta-thalassemia is being corrected in mice by continous erythropoeitin delivery from engineered muscles cells, and from naked DNA electrotransfer into muscles, as described by Dr JM Heard (Institut Pasteur, Paris, France). Dr Reszka (Max-Delbrueck-Centrum fuer Molekulare Medizin, Berlin, Germany), meanwhile, described a treatment for liver metastasis in the form of a drug carrier emolization system, DCES (Max-Delbrueck-Centrum fuer Molekulare Medizin), composed of surface modified liposomes and a substance for chemo-occlusion, which drastically reduces the blood supply to the tumor and promotes apoptosis, necrosis and antiangiogenesis. In the molecular tools section, Willem Stemmer (Maxygen Inc, Redwood City, CA, USA) gave an insight into the importance that techniques, such as molecular breeding (DNA shuffling), have in the evolution of molecules with improved function, over a range of fields including pharmaceuticals, vaccines, agriculture and chemicals. Technologies, such as ribosome display, which can incorporate the evolution and the specific enrichment of proteins/peptides in cycles of selection, could play an enormous role in the production of novel therapeutics and diagnostics in future years, as explained by Andreas Plückthun (Institute of Biochemistry, University of Zurich, Switzerland). Applied genome research offered technologies, such as the 'in vitro expression cloning', described by Dr Zwick (Promega Corp, Madison, WI, USA), are providing a functional analysis for the overwhelming flow of data emerging from high-throughput sequencing of genomes and from high-density gene expression microarrays (DNA chips). The importance of bioinformatics was stressed throughout the conference. In particular, its applications in the storage, analysis and visualization of data, but also the linkage of databases and data mining tools. It is the storage and linkage that generates insight into disease processes, enabling the nomination of candidate drug targets.

Analysis of mutants of tetanus toxin Hc fragment: ganglioside binding, cell binding and retrograde axonal transport properties

Tetanus toxin binds neuronal tissue prior to internalization and trafficking to the central nervous system. Binding of the carboxy-terminal 50 kDa HC fragment of tetanus toxin to polysialogangliosides is important for this initial cell binding step. Using the three-dimensional structure of HC, mutants were designed to investigate the role of individual residues in ganglioside binding. Mutant proteins were tested for binding to GT1b gangliosides, to primary motoneurons and for their ability to undergo retrograde transport in mice. Two classes of mutant were obtained: (i) those containing deletions in loop regions within the C-terminal beta-trefoil domain which showed greatly reduced ganglioside and cell binding and did not undergo retrograde transport and (ii) those that showed reduced ganglioside binding, but retained primary neuronal cell binding and retrograde transport. The second class included point mutants of Histidine-1293, previously implicated in GT1b binding. Our deletion analysis is entirely consistent with recent structural studies which have identified sugar-binding sites in the immediate vicinity of the residues identified by mutagenesis. These results demonstrate that ganglioside binding can be severely impaired without abolishing cell binding and intracellular trafficking of tetanus toxin.

Retargeting of adenoviral vectors to neurons using the Hc fragment of tetanus toxin

The Hc fragment of tetanus toxin (Hc) retains the specific nerve cell binding and transport properties of the holotoxin, but lacks any toxicity. We are investigating the potential for utilising its neurotropism for targeted gene delivery to the central nervous system. Previously we reported the use of Hc-polylysine conjugates for selective gene transfer into neuronal cells in vitro. However, as attempts to apply these constructs in vivo were not successful, we have extended these studies to modification of the tropism of adenoviral vectors. Either Hc-polylysine conjugates or the Fab fragment of a neutralising anti-knob antibody covalently bound to Hc were attached to the virus. Infection of neuronal and non-neuronal cell lines with retargeted virus showed highly increased neuronal cell selectivity, but no significant enhancement of gene delivery into these cells. High concentrations of free Hc blocked the infectivity of the retargeted vector efficiently. Intramuscular injection of retargeted virus into mouse tongues resulted in selective gene transfer to the neurons of the hypoglossal nucleus, where no pathological changes were observed. As differentiated neurons do not undergo cell division, appropriate vectors carrying a thymidine kinase gene, which allows selective elimination of dividing cells, may be exploitable for the treatment of tumours of the central nervous system. The demonstrated suitability of the Hc fragment of tetanus toxin as targeting moiety for viral vectors also indicates a potential for gene therapy of inherited neurodegenerative diseases such as spinal muscular atrophy.

Early entry and widespread cellular involvement of HIV-1 DNA in brains of HIV-1 positive asymptomatic individuals

There is overwhelming evidence that invasion of the central nervous system (CNS) by HIV-1 takes place at an early stage of the infection. It has been demonstrated that HIV-1 DNA is present in brains of asymptomatic individuals. Evidence of immune activation and increased expression of cytokines suggested that neuropathological changes and neuronal and axonal damage could be the effect of the presence of the virus. The purpose of the study is to ascertain whether target cells for HIV-1 in brain of patients at early stage of the infection are the same as those found in AIDS sufferers or if the distribution seen in AIDS patients results from the late spreading of the infection from cells considered traditionally the reservoir of the virus, i.e. microglial cells. Eighteen brains, all HIV-1 DNA positive, as shown by nested polymerase chain reaction (PCR), were selected among the group of HIV-1 positive asymptomatic cases. In 6 of them, HIV-1 DNA was detected by PCR in situ. Positive cells included astrocytes and endothelial cells, in addition to microglial cells. We conclude that astrocytes and endothelial cells are already infected at an early (asymptomatic) stage of the infection and suggest that they might contribute to the damage of the CNS.

Detection and localisation of HIV-1 DNA and RNA in fixed adult AIDS brain by polymerase chain reaction/in situ hybridisation technique

In the brain of patients with AIDS, HIV-1 is localised in a productive form in mononuclear cells. One issue that still needs clarification is whether HIV is localised in cells other than those of mononuclear lineage. Gene amplification by polymerase chain reaction/in situ hybridisation (PCR-IS) could shed light on it. In this study, formalin-fixed, paraffin-embedded brain tissue from ten adult AIDS sufferers was used. Five of them showed evidence of HIV encephalitis (HIVE), five did not show any abnormality. Nested PCR revealed HIV-1 DNA in all HIVE cases and in three of the group without HIVE. HIV-1 DNA and RNA were also detected in situ in seven cases (all seven were also HIV-1 DNA positive in tube). A higher signal was located in the white than in the grey matter. HIV-1 DNA was found in microglia, macrophages, perivascular cells, multinucleated gaint cells (MGC) and in CD68-negative cells. Some of them were identified as endothelial cells, astrocytes and oligodendrocytes. Reverse transcriptase-PCR-IS was positive in macrophages, MGC, endothelial and glial cells. These results confirm infection of endothelial cells and other glial cells and give clues about the route of entry of virus into the central nervous system and the pathogenesis of the disease. This study did not give any convincing evidence supporting an infection of neurons by HIV-1.

Poor response rate to a continuous schedule of Amifostine therapy for 'low/intermediate risk' myelodysplastic patients

Ineffective haemopoiesis leading to cytopenia presents the major clinical management problem for patients with myelodysplasia (MDS). Preliminary studies have demonstrated that the synthetic aminothiol Amifostine stimulates multilineage haemopoiesis both in vitro and in vivo in patients with MDS. We have treated 12 patients with an uninterrupted 8-week schedule of thrice-weekly intravenous Amifostine with a starting dose of 300 mg/m2 escalating to 450 mg/m2 in non-responders. No patients satisfied response criteria on study but two patients showed minor responses. We conclude that therapeutic response to Amifostine in MDS may be schedule dependent.

Axonal damage revealed by accumulation of beta-APP in HIV-positive individuals without AIDS

The presence of neuropsychological disturbances in HIV-positive, pre-symptomatic individuals is a controversial issue. Neuroimaging studies have not shown brain atrophy or hyperintensity in the white matter, whereas proton magnetic resonance spectroscopy has revealed some abnormality of cerebral biochemistry. Using an antibody to beta-amyloid precursor protein (beta-APP), we previously demonstrated frequent and widespread axonal changes in the brains of AIDS patients. In this study, we extended the use of beta-APP to asymptomatic patients in order to establish a possible morphological correlation with neuropsychological disorders. Brain samples from 29 patients were examined. Results showed bundles of beta-APP-positive axons in 8/29 cases (27%). The changes, seen in both superficial and deep white matter, were either focal or diffuse, could not be visualized by silver or ubiquitin stains, and did not coexist with any change in distribution or morphology of astrocytes and microglial cells. We conclude that in HIV-positive asymptomatic individuals, axonal changes: (a) may be related to the state of immune activation with consequent presence of toxic substances, including cytokines, observed in these patients; (b) may represent mild changes that could undergo repair, unless other pathological events, such as the supervening of the AIDS stage and the specific encephalitis, make them permanent.

Accumulation of beta-amyloid precursor protein in HIV encephalitis: relationship with neuropsychological abnormalities

The pathogenesis of neuropsychological abnormalities in patients with human immunodeficiency virus type 1 (HIV-1) encephalitis is obscure because neurons are not the target of infection and severe neuronal loss occurs only late during the disease. Moreover, there is evidence indicating that HIV dementia is not a homogeneous entity and could partially reverse after treatment with zidovudine. The finding that impaired axonal flow, evidenced by beta-amyloid precursor protein immunoreactivity, could contribute to the neuropsychological deficits prompted the present study. Brains of patients with full-blown acquired immunodeficiency syndrome (AIDS) were studied and findings compared with those of normal and abnormal control subjects. The presence of HIV-1 DNA was investigated by nested polymerase chain reaction; axonal abnormalities were detected by beta-amyloid precursor protein, ubiquitin immunohistochemistry, and silver staining. Accumulation of beta-amyloid precursor protein was observed in all the HIV encephalitis brains studied; the appearance of the immunostaining varied from globular structures to bundles of parallel formations. In 2 AIDS brains without pathological abnormalities, only the latter pattern was detected. The brains with trauma were strongly reactive with beta-amyloid precursor protein antibody and the different reactivity within them correlated with posttrauma survival, only globular structures being detected in the older cases. No correlation was found between the different pattern of beta-amyloid precursor protein reactivity and dementia in AIDS patients. These results show that widespread axonal injury is a constant feature in AIDS brains and suggest that it could play a role in the pathogenesis of the neuropsychological abnormalities of these patients.