Canadian Consensus for Biomarker Testing and Treatment of TRK Fusion Cancer in Pediatric Patients

Neurotrophic tyrosine receptor kinase gene fusions (NTRK) are oncogenic drivers present at a low frequency in most tumour types (<5%), and at a higher frequency (>80%) in a small number of rare tumours (e.g., infantile fibrosarcoma [IFS]) and considered mutually exclusive with other common oncogenic drivers. Health Canada recently approved two tyrosine receptor kinase (TRK) inhibitors, larotrectinib (for adults and children) and entrectinib (for adults), for the treatment of solid tumours harbouring NTRK gene fusions. In Phase I/II trials, these TRK inhibitors have demonstrated promising overall response rates and tolerability in patients with TRK fusion cancer who have exhausted other treatment options. In these studies, children appear to have similar responses and tolerability to adults. In this report, we provide a Canadian consensus on when and how to test for NTRK gene fusions and when to consider treatment with a TRK inhibitor for pediatric patients with solid tumours. We focus on three pediatric tumour types: non-rhabdomyosarcoma soft tissue sarcoma/unspecified spindle cell tumours including IFS, differentiated thyroid carcinoma, and glioma. We also propose a tumour-agnostic consensus based on the probability of the tumour harbouring an NTRK gene fusion. For children with locally advanced or metastatic TRK fusion cancer who have either failed upfront therapy or lack satisfactory treatment options, TRK inhibitor therapy should be considered.     

Naturally processed and presented epitopes of the islet cell autoantigen IA-2 eluted from HLA-DR4

During immune responses, antigen-presenting cells (APCs) process antigens and present peptide epitopes complexed with human leukocyte antigen (HLA) molecules. CD4 cells recognize these naturally processed and presented epitopes (NPPEs) bound to HLA class II molecules. Epitope identification is important for developing diagnostic and therapeutic tools for immune-mediated diseases and providing insight into their etiology, but current approaches overlook effects of natural processing on epitope selection. We have developed a technique to identify NPPEs using mass spectrometry (MS) after antigen is targeted onto APCs using a lectin-based antigen delivery system (ADS). We applied the technique to identify NPPEs of the intracellular domain of the type 1 diabetes mellitus-associated (type 1 DM-associated) autoantigen insulinoma-associated-2 (IA-2ic), presented by HLA-DR4 (0401). IA-2ic-derived NPPEs eluted from HLA-DR4 constitute 6 sets of peptides nested around distinct core regions. Synthetic peptides based on these regions bind HLA-DR4 and elicit primary T-cell proliferation frequently in HLA-DR4-positive type 1 DM patients, but rarely in non-HLA-DR4 patients, and in none of the HLA-DR4 nondiabetic controls we tested. This flexible, direct approach identifies an HLA allele-specific map of NPPEs for any antigen, presented by any HLA class II molecule. This method should enable a greater understanding of epitope selection and lead to the generation of sensitive and specific reagents for detecting autoreactive T cells.     

Safety and efficacy of simultaneous bilateral 25-gauge lens-sparing vitrectomy for vascularly active stage 4 retinopathy of prematurity

Purpose

To report the safety and efficacy of simultaneous bilateral 25-gauge lens-sparing vitrectomy for vascularly active stage 4 retinopathy of prematurity (ROP).

Methods

Retrospective, noncomparative, consecutive case series. Twenty eyes of 10 babies who presented with vascularly active stage 4 ROP in both the eyes underwent simultaneous bilateral 25-gauge lens-sparing vitrectomy. After completing surgery for one eye, the other eye was re-prepped as performed before starting any new case of a different patient and an entire new set of disposable 25-gauge instruments were used. During the post-operative period parents were advised to keep separate eye drops for each eye and to wash their hands in between switching the eyes to put the drops.

Results

The mean follow-up was 8.7 months (range 4–17 months). None of the cases developed any signs of infection. The anatomic success rate for stage 4a was 100% (11/11 eyes) and for stage 4b was 8/9 eyes (89%).

Conclusion

These results show that simultaneous bilateral 25-gauge lens-sparing vitrectomy for stage 4 ROP is a safe and effective procedure with a good outcome provided both eyes of the baby are treated as eyes of two different patients.     

In vitro screen of a small molecule inhibitor drug library identifies multiple compounds that synergize with oncolytic myxoma virus against human brain tumor-initiating cells

Background

Brain tumor-initiating cells (BTICs) are stem-like cells hypothesized to form a disease reservoir that mediates tumor recurrence in high-grade gliomas. Oncolytic virotherapy uses replication-competent viruses to target and kill malignant cells and has been evaluated in clinic for glioma therapy with limited results. Myxoma virus (MyxV) is a safe and highly effective oncolytic virus (OV) in conventional glioma models but, as seen with other OVs, is only modestly effective for patient-derived BTICs. The objective of this study was to determine whether MyxV treatment against human BTICs could be improved by combining chemotherapeutics and virotherapy.

Methods

A 73-compound library of drug candidates in clinical use or preclinical development was screened to identify compounds that sensitize human BTICs to MyxV treatment in vitro, and synergy was evaluated mathematically in lead compounds using Chou-Talalay analyses. The effects of combination therapy on viral gene expression and viral replication were also assessed.

Results

Eleven compounds that enhance MyxV efficacy were identified, and 6 were shown to synergize with the virus using Chou-Talalay analyses. Four of the synergistic compounds were shown to significantly increase viral gene expression, indicating a potential mechanism for synergy. Three highly synergistic compounds (axitinib, a VEGFR inhibitor; rofecoxib, a cyclooxygenase-2 inhibitor; and pemetrexed, a folate anti-metabolite) belong to classes of compounds that have not been previously shown to synergize with oncolytic viruses in vitro.

Conclusions

This study has identified multiple novel drug candidates that synergistically improve MyxV efficacy in a preclinical BTIC glioma model.     

Outcomes of Intra- and Extraocular Retinoblastomas from a Single Institute in South India

Aim: To report treatment outcomes of intra- and extraocular retinoblastomas seen at Aravind Eye Hospital, Coimbatore, South India.

Methods: Retrospective case series from January 2006 to December 2011 involving 106 babies. Clinical records were reviewed and data collected on presenting signs, gender, age, family history, ocular findings and treatment outcomes. All eyes were classified using the International Retinoblastoma Classification.

Results: The mean follow up was 35.4 months (range 1–75 months, SD 20.2, median 33 months). The mean age of presentation was 20.8 months (range 5 days to 120 months). There were 68 unilateral and 38 bilateral cases. Globe salvage rates were 100% for group A (11 eyes), B (16 eyes) and C (2 eyes). For group D, eye salvage rate was 29.5% (10/34 eyes). Survival rate of orbital retinoblastoma in our study was 55.5% (5/9 cases) at a mean follow up of 33.6 months. The overall patient survival rate was 89.6% with 11 deaths (10.4%). The commonest cause of death (7/11) was distant metastasis due to refusal to take initial treatment.

Conclusion: Greater improvement in patient survival can be achieved not only by early treatment of intraocular disease but also to convince patients to accept treatments including enucleation in this part of the world.     

Filamentous fungal infections of the cornea: a global overview of epidemiology and drug sensitivity

Fungal keratitis is a serious suppurative, usually ulcerative corneal infection which may result in blindness or reduced vision. Epidemiological studies indicate that the occurrence of fungal keratitis is higher in warm, humid regions with agricultural economy. The most frequent filamentous fungal genera among the causal agents are Fusarium, Aspergillus and Curvularia. A more successful therapy of fungal keratitis relies on precise identification of the pathogen to the species level using molecular tools. As the sequence analysis of the internal transcribed spacer (ITS) region of the ribosomal RNA gene cluster (rDNA) is not discriminative enough to reveal a species‐level diagnosis for several filamentous fungal species highly relevant in keratitis infections, analysis of other loci is also required for an exact diagnosis. Molecular identifications may also reveal the involvement of fungal species which were not previously reported from corneal infections. The routinely applied chemotherapy of fungal keratitis is based on the topical and systemic administration of polyenes and azole compounds. Antifungal susceptibility testing of the causal agents is of special importance due to the emergence and spread of resistance. Testing the applicability of further available antifungals and screening for new, potential compounds for the therapy of fungal keratitis are of highlighted interest.     

Increased Left Ventricular Torsion in Uncomplicated Type 1 Diabetic Patients: The role of coronary microvascular function

OBJECTIVE

We used speckle tracking echocardiography to study the early changes in left ventricular (LV) torsion in young patients with uncomplicated type 1 diabetes and stress magnetic resonance imaging (MRI) to assess its interrelationships with coronary microangiopathy.

RESEARCH DESIGN AND METHODS

We recruited 33 asymptomatic subjects with type 1 diabetes and 32 age-matched healthy control subjects. All subjects underwent echocardiograms. Stress MRIs were performed in 30 subjects (8 healthy control subjects) to compute myocardial perfusion reserve index (MPRI).

RESULTS

A significant increase in LV torsion (2 ± 0.7 vs. 1.4 ± 0.7°/cm, P < 0.05) was identified in longer-term and retinopathy-positive type 1 diabetic subjects (1.9 ± 0.7 vs. 1.4 ± 0.7°/cm, P < 0.05) as compared with the healthy control subjects. The MPRI was independently associated with increased LV torsion.

CONCLUSIONS

We demonstrate that LV torsion is increased in young patients with uncomplicated type 1 diabetes and that coronary microvascular disease may play a key pathophysiological role in the development of increased LV torsion.There is increasing evidence for the presence of diabetic cardiomyopathy as a separate entity. However, detection of early changes in the myocardium is challenging in patients with diabetes. Speckle tracking echocardiography is a novel method of measuring left ventricular (LV) strain and rotation (1,2). Previous studies with tagged magnetic resonance imaging (MRI) have shown increased torsion in both patients with type 1 and type 2 diabetes (3,4). The main aim of this study was to confirm and extend these findings by exploring the potential pathophysiological mechanisms involved. We utilized speckle tracking to measure LV torsion and stress MRI to compute myocardial perfusion reserve index (MPRI), which is a measure of coronary microvascular function.