Long-term efficacy of dolutegravir plus lamivudine for maintenance of HIV viral suppression in adults with and without historical resistance to lamivudine: Week 96 results of ART-PRO pilot study

BACKGROUND

In the ART-PRO pilot trial there were no virological failures through 48 weeks of treatment with dolutegravir plus lamivudine in suppressed individuals with and without archived lamivudine resistance-associated mutations (RAMs) detected through next-generation sequencing (NGS) but without evidence of lamivudine RAMs in baseline proviral DNA population sequencing.

OBJECTIVES

To present 96 week results from ART-PRO.

METHODS

Open-label, single-arm pilot trial. At baseline, all participants switched to dolutegravir plus lamivudine. Participants were excluded if proviral DNA population genotyping detected lamivudine RAMs. To detect resistance minority variants, proviral DNA NGS was retrospectively performed from baseline samples. For this analysis the efficacy endpoint was the proportion of participants with <50 HIV-1 RNA copies/mL at week 96. Safety and tolerability outcomes were incidence of adverse events and treatment discontinuations.

RESULTS

Forty-one participants were included, 21 with lamivudine RAMs in historical plasma RNA genotypes. Baseline proviral DNA NGS detected lamivudine RAMs (M184V/I and/or K65R/E/N) above a 5% threshold in 71.4% (15/21) and 15% (3/20) of participants with and without history of lamivudine resistance, respectively. At 96 weeks, 90.2% of participants achieved the efficacy endpoint. Between week 48 and 96 there was one discontinuation due to consent withdrawal and no discontinuations related to adverse events. Two participants had a transient viral rebound, both re-suppressed on dolutegravir plus lamivudine. Through week 96, there were no virological failures.

CONCLUSIONS

In this pilot trial, dolutegravir plus lamivudine maintained virological suppression at 96 weeks despite historical lamivudine resistance and persisting archived minority lamivudine RAMs.

Mitochondrial DNA depletion: mutations in thymidine kinase gene with myopathy and SMA

BACKGROUND

The mitochondrial DNA (mtDNA) depletion syndrome (MDS) is an autosomal recessive disorder of early childhood characterized by decreased mtDNA copy number in affected tissues. Recently, MDS has been linked to mutations in two genes involved in deoxyribonucleotide (dNTP) metabolism: thymidine kinase 2 (TK2) and deoxy-guanosine kinase (dGK). Mutations in TK2 have been associated with the myopathic form of MDS, and mutations in dGK with the hepatoencephalopathic form.

OBJECTIVES

To further characterize the frequency and clinical spectrum of these mutations, the authors screened 20 patients with myopathic MDS.

RESULTS

No patient had dGK gene mutations, but four patients from two families had TK2 mutations. Two siblings were compound heterozygous for a previously reported H90N mutation and a novel T77M mutation. The other siblings harbored a homozygous I22M mutation, and one of them had evidence of lower motor neuron disease. The pathogenicity of these mutations was confirmed by reduced TK2 activity in muscle (28% to 37% of controls).

CONCLUSIONS

These results show that the clinical expression of TK2 mutations is not limited to myopathy and that the myopathic form of MDS is genetically heterogeneous.

Erythrocyte 3-O-methyl-D-glucose uptake assay for diagnosis of glucose-transporter-protein syndrome

Glucose transport into the brain is mediated by a facilitative glucose-transporter protein, GLUT-1. A GLUT-1 defect results in the Glucose-Transporter-Protein Syndrome (GTPS), characterized by infantile epilepsy, developmental delay, and acquired microcephaly. The diagnosis is currently based on clinical features, low to normal lactate levels and low glucose levels (hypoglycorrhachia) in the cerebrospinal fluid, and the demonstration of impaired GLUT-1 function in erythrocytes as described here. Blood samples were collected in sodium-heparin or citrate-phosphate-dextrose solution and uptake of 14C-labeled 3-O-Methyl-D-glucose (3OMG into erythrocytes (0.5 mmol/L 3OMG; 1 microCi/mL) was measured at 4C and pH 7.4. Three-OMG influx was terminated at 5-second intervals, washed cells were lysed, and uptake was quantitated by liquid scintillation counting. Patients' uptake (n = 22) was 44 +/- 8% of controls (100 +/- 22%, n = 70). Statistical analyses showed an uptake cut-off point at 60% uptake, a sensitivity of 86% (95%-confidence interval 78 to 94%), and a specificity of 97% (95%-confidence interval 93 to 100%). Gender, age, and ketosis did not influence 3OMG uptake. This assay provides a reproducible and accurate laboratory test for diagnosing the GTPS.