Faricimab Treat-and-Extend for Diabetic Macular Edema: Two-Year Results from the Randomized Phase 3 YOSEMITE and RHINE Trials.

PURPOSE: To evaluate the 2-year efficacy, durability, and safety of dual angiopoietin-2 and vascular endothelial growth factor (VEGF) A pathway inhibition with intravitreal faricimab according to a personalized treat-and-extend (T&E)-based regimen with up to every-16-week dosing in the YOSEMITE and RHINE (ClinicalTrials.gov identifiers, NCT03622580 and NCT03622593, respectively) phase 3 trials of diabetic macular edema (DME). DESIGN: Randomized, double-masked, noninferiority phase 3 trials. PARTICIPANTS: Adults with visual acuity loss (best-corrected visual acuity [BCVA] of 25-73 letters) due to center-involving DME. METHODS: Patients were randomized 1:1:1 to faricimab 6.0 mg every 8 weeks, faricimab 6.0 mg T&E (previously referred to as personalized treatment interval), or aflibercept 2.0 mg every 8 weeks. The T&E up to every-16-week dosing regimen was based on central subfield thickness (CST) and BCVA change. MAIN OUTCOME MEASURES: Included changes from baseline in BCVA and CST, number of injections, durability, absence of fluid, and safety through week 100. RESULTS: In YOSEMITE and RHINE (n = 940 and 951, respectively), noninferior year 1 visual acuity gains were maintained through year 2; mean BCVA change from baseline at 2 years (weeks 92, 96, and 100 average) with faricimab every 8 weeks (YOSEMITE and RHINE, +10.7 letters and +10.9 letters, respectively) or T&E (+10.7 letters and +10.1 letters, respectively) were comparable with aflibercept every 8 weeks (+11.4 letters and +9.4 letters, respectively). The median number of study drug injections was lower with faricimab T&E (YOSEMITE and RHINE, 10 and 11 injections, respectively) versus faricimab every 8 weeks (15 injections) and aflibercept every 8 weeks (14 injections) across both trials during the entire study. In the faricimab T&E arms, durability was improved further during year 2, with > 60% of patients receiving every-16-week dosing and approximately 80% receiving every-12-week or longer dosing at week 96. Almost 80% of patients who achieved every-16-week dosing at week 52 maintained every-16-week dosing without an interval reduction through week 96. Mean CST reductions were greater (YOSEMITE/RHINE weeks 92/96/100 average: faricimab every 8 weeks -216.0/-202.6 µm, faricimab T&E -204.5/-197.1 µm, aflibercept every 8 weeks -196.3/-185.6 µm), and more patients achieved absence of DME (CST < 325 µm; YOSEMITE/RHINE weeks 92-100: faricimab every 8 weeks 87%-92%/88%-93%, faricimab T&E 78%-86%/85%-88%, aflibercept every 8 weeks 77%-81%/80%-84%) and absence of intraretinal fluid (YOSEMITE/RHINE weeks 92-100: faricimab every 8 weeks 59%-63%/56%-62%, faricimab T&E 43%-48%/45%-52%, aflibercept every 8 weeks 33%-38%/39%-45%) with faricimab every 8 weeks or T&E versus aflibercept every 8 weeks through year 2. Overall, faricimab was well tolerated, with a safety profile comparable with that of aflibercept. CONCLUSIONS: Clinically meaningful visual acuity gains from baseline, anatomic improvements, and extended durability with intravitreal faricimab up to every 16 weeks were maintained through year 2. Faricimab given as a personalized T&E-based dosing regimen supports the role of dual angiopoietin-2 and VEGF-A inhibition to promote vascular stability and to provide durable efficacy for patients with DME. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

TENAYA and LUCERNE: Two-Year Results from the Phase 3 Neovascular Age-Related Macular Degeneration Trials of Faricimab with Treat-and-Extend Dosing in Year 2.

PURPOSE: To evaluate 2-year efficacy, durability, and safety of the bispecific antibody faricimab, which inhibits both angiopoietin-2 and VEGF-A. DESIGN: TENAYA (ClinicalTrials.gov identifier, NCT03823287) and LUCERNE (ClinicalTrials.gov identifier, NCT03823300) were identically designed, randomized, double-masked, active comparator-controlled phase 3 noninferiority trials. PARTICIPANTS: Treatment-naive patients with neovascular age-related macular degeneration (nAMD) 50 years of age or older. METHODS: Patients were randomized (1:1) to intravitreal faricimab 6.0 mg up to every 16 weeks (Q16W) or aflibercept 2.0 mg every 8 weeks (Q8W). Faricimab fixed dosing based on protocol-defined disease activity at weeks 20 and 24 up to week 60, followed up to week 108 by a treat-and-extend personalized treatment interval regimen. MAIN OUTCOME MEASURES: Efficacy analyses included change in best-corrected visual acuity (BCVA) from baseline at 2 years (averaged over weeks 104, 108, and 112) and proportion of patients receiving Q16W, every 12 weeks (Q12W), and Q8W dosing at week 112 in the intention-to-treat population. Safety analyses included ocular adverse events (AEs) in the study eye through study end at week 112. RESULTS: Of 1326 patients treated across TENAYA/LUCERNE, 1113 (83.9%) completed treatment (n = 555 faricimab; n = 558 aflibercept). The BCVA change from baseline at 2 years was comparable between faricimab and aflibercept groups in TENAYA (adjusted mean change, +3.7 letters [95% confidence interval (CI), +2.1 to +5.4] and +3.3 letters [95% CI, +1.7 to +4.9], respectively; mean difference, +0.4 letters [95% CI, -1.9 to +2.8]) and LUCERNE (adjusted mean change, +5.0 letters [95% CI, +3.4 to +6.6] and +5.2 letters [95% CI, +3.6 to +6.8], respectively; mean difference, -0.2 letters [95% CI, -2.4 to +2.1]). At week 112 in TENAYA and LUCERNE, 59.0% and 66.9%, respectively, achieved Q16W faricimab dosing, increasing from year 1, and 74.1% and 81.2%, achieved Q12W or longer dosing. Ocular AEs in the study eye were comparable between faricimab and aflibercept groups in TENAYA (55.0% and 56.5% of patients, respectively) and LUCERNE (52.9% and 47.5% of patients, respectively) through week 112. CONCLUSIONS: Treat-and-extend faricimab treatment based on nAMD disease activity maintained vision gains through year 2, with most patients achieving extended dosing intervals. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Phenotypic evaluation of previously uncharacterized cytomegalovirus DNA polymerase sequence variants detected in a valganciclovir treatment trial.

BACKGROUND: In a large randomized trial comparing oral valganciclovir and intravenous ganciclovir for treatment of cytomegalovirus disease in solid organ transplantation, confirmed genotypic drug resistance was uncommon (<5%), but definitive interpretation was limited by the detection of 110 uncharacterized UL54 viral DNA polymerase sequence variants. METHODS: Based on treatment history and genetic locus of the sequence changes, 39 of the sequence variants were prioritized for recombinant phenotyping by construction of cloned viral mutants and drug susceptibility testing in cell culture. RESULTS: Four amino acid substitutions were newly confirmed to alter ganciclovir susceptibility: A505V and I726T conferred a borderline decrease in ganciclovir and cidofovir susceptibility, while Q578L and G841S conferred slightly decreased ganciclovir and foscarnet susceptibility. A nonviable phenotype was found for 8 mutations distributed among amino terminal, exonuclease and catalytic domains. Retesting of stored study specimens could not confirm the original detection of >20 sequence variants, including the nonviable mutations and several resistance mutations. CONCLUSIONS: Newly phenotyped UL54 sequence variants did not significantly change the reported incidence of drug resistance in the clinical trial. Unrecognized sequence variants in diagnostic genotyping reports should be confirmed by additional testing in order to improve clinical decision making.

Efficacy, Durability, and Safety of Faricimab in Patients From Asian Countries With Diabetic Macular Edema: 1-Year Subgroup Analysis of the Phase III YOSEMITE and RHINE Trials.

PURPOSE: To assess the 1-year efficacy, durability, and safety of faricimab in patients with diabetic macular edema from Asian and non-Asian countries. DESIGN: Global, multicenter, randomized, double-masked, active comparator-controlled, phase III trials. METHODS: Subgroup analysis of patients from Asian (N=144) and non-Asian (N=1747) countries randomized to faricimab 6.0 mg every 8 weeks (Q8W), faricimab per personalized treatment interval (PTI), or aflibercept 2.0 mg Q8W in the YOSEMITE/RHINE (NCT03622580/NCT03622593) trials. Primary endpoint: best-corrected visual acuity (BCVA) changes from baseline at 1 year, averaged over weeks 48, 52, and 56. RESULTS: Mean BCVA change from baseline at 1 year in the Asian country subgroup was similar between arms: faricimab Q8W (n=50), +10.9 (95% CI: 8.6-13.2); faricimab PTI (n=48) +10.0 (7.7-12.4) letters; aflibercept Q8W (n=46) +9.0 (6.6-11.4) letters. BCVA gains in the non-Asian country subgroup (n=582, 584, 581) were +11.3 (10.5-12.1), +11.2 (10.5-12.0), and +10.7 (9.9-11.5) letters, respectively. At 1 year, 49% of Asian country patients in the faricimab PTI arm achieved Q16W dosing (vs. 52% non-Asian) and 78% achieved ≥Q12W dosing (vs. 72% non-Asian). Anatomic improvementswere generally greater with faricimab versus aflibercept and similar between the Asian and non-Asian country subgroups. Faricimab was well tolerated, with no new safety signals. CONCLUSIONS: Vision, durability, anatomic, and safety outcomes were generally similar between the Asian and non-Asian country subgroups, suggesting that global YOSEMITE/RHINE results may be generalized to the Asian population. These data support the benefit-risk profile of faricimab for treating Asian patients with diabetic macular edema.

Prevalence and Progression of Macular Atrophy in Eyes with Neovascular Age-Related Macular Degeneration in the Phase 2 Ladder Trial of the Port Delivery System with Ranibizumab.

PURPOSE: To determine whether the rates of macular atrophy (MA) differ between eyes with neovascular age-related macular degeneration (nAMD) treated continuously with the Port Delivery System with ranibizumab (PDS) and those treated with ranibizumab given as a bolus intravitreal injection. DESIGN: A preplanned exploratory analysis of a phase 2, multicenter, randomized, active treatment-controlled, dose-ranging study. PARTICIPANTS: Patients diagnosed with nAMD within 9 months of screening who had received at least 2 previous intravitreal anti-vascular endothelial growth factor injections of any agent and were responsive to the treatment. METHODS: Eyes were randomized (3:3:3:2) to treatment with either the PDS (filled with a customized formulation of ranibizumab at 10, 40, or 100 mg/ml and refilled pro re nata) or monthly intravitreal ranibizumab 0.5-mg injections. MAIN OUTCOME MEASURES: The prevalence, incidence, and progression of MA. RESULTS: The analysis population consisted of 220 eyes (58, 62, 59, and 41 eyes in the PDS 10-mg/ml, 40-mg/ml, 100-mg/ml, and monthly intravitreal ranibizumab 0.5-mg injection arms, respectively). At study baseline, MA was observed in 14.5% (PDS 10-mg/ml), 11.5% (PDS 40-mg/ml), 13.6% (PDS 100-mg/ml), and 7.6% (monthly ranibizumab) of eyes. At the last assessment (mean, 22.1 months), the prevalence of MA had increased to 38.6% (PDS 10-mg/ml), 40.0% (PDS 40-mg/ml), 40.4% (PDS 100-mg/ml), and 45.7% (monthly ranibizumab). In patients without MA at baseline, a higher proportion of eyes in the monthly ranibizumab arm (40.6%) developed MA than in those in the PDS arms (28.6%, 32.1%, and 30.6% of eyes in the PDS 10-, 40-, and 100-mg/ml arms, respectively). The mean change in the area of MA from baseline to the last assessment for the PDS 10-mg/ml, 40-mg/ml, 100-mg/ml, and monthly ranibizumab arms was +2.46, +1.61, +1.09, and +1.15 mm2, respectively. At 9 months, for patients without MA at baseline, the difference in the incidence of MA between the PDS 100-mg/ml and monthly ranibizumab groups was -12% (95% confidence interval, -31% to 7%). CONCLUSIONS: In the phase 2 Ladder trial, there was no evidence of worse MA with the PDS compared with that with monthly intravitreal ranibizumab 0.5-mg injections. Larger trials focusing on MA are needed to confirm this finding.

Long-term follow-up of patients with type 2 and non-ambulant type 3 spinal muscular atrophy (SMA) treated with olesoxime in the OLEOS trial.

In a previous Phase 2 study, olesoxime had a favorable safety profile. Although the primary endpoint was not met, analyses suggested that olesoxime might help in the maintenance of motor function in patients with Types 2/3 SMA. This open-label extension study (OLEOS) further characterizes the safety, tolerability and efficacy of olesoxime over longer therapy durations. In OLEOS, no new safety risks were identified. Compared to matched natural history data, patients treated with olesoxime demonstrated small, non-significant changes in motor function over 52 weeks. Motor function scores were stable for 52 weeks but declined over the remainder of the study. The greatest decline in motor function was seen in patients ≤15 years old, and those with Type 2 SMA had faster motor function decline versus those with Type 3 SMA. Previous treatment with olesoxime in the Phase 2 study was not protective of motor function in OLEOS. Respiratory outcomes were stable in patients with Type 3 SMA >15 years old but declined in patients with Type 2 SMA and in patients with Type 3 SMA ≤15 years old. Overall, with no stabilization of functional measures observed over 130 weeks, OLEOS did not support significant benefit of olesoxime in patients with SMA.

Cytomegalovirus resistance in solid organ transplant recipients treated with intravenous ganciclovir or oral valganciclovir.

BACKGROUND: The rate of cytomegalovirus (CMV) mutations conferring ganciclovir resistance was assessed in a trial comparing intravenous ganciclovir and oral valganciclovir for treatment of CMV disease in solid organ transplant (SOT) recipients. METHODS: Viral genes (UL97 and UL54) conferring ganciclovir resistance were amplified and sequenced from blood samples collected at days 0 (before therapy), 21 (end of induction) and 49 (end of maintenance). RESULTS: The overall risk of developing a confirmed or probable ganciclovir resistance mutation during treatment was similar for patients treated with ganciclovir (2.3%) and valganciclovir (3.6%; P=0.51). A persistent viral load at day 21 was associated with a significant risk of ganciclovir resistance by day 49 (odds ratio 11.83; P=0.022). In multivariate analyses, presence of a confirmed ganciclovir resistance mutation was independently associated with virological failure (viral load > or =600 copies/ml) at days 21 and 49. One-third (3/9) of patients with confirmed CMV resistance mutations had recurrent CMV disease. The plasma half-life of confirmed ganciclovir-resistant UL97 mutants was significantly longer than that of wild-type strains, polymorphic variants and strains with mutations of unknown significance (P=0.045). Multiple UL54 mutations of unknown significance were found in clinical strains. Viral kinetic analysis of these latter strains revealed no effect (negative or positive) on in vivo viral fitness. CONCLUSIONS: Treatment with oral valganciclovir or intravenous ganciclovir results in similar and low rates of resistance mutations in SOT recipients. Patients with drug-resistant CMV strains often have virological failure and might have unfavourable clinical outcomes.

Pharmacokinetics, efficacy, and safety of mycophenolate mofetil in combination with standard-dose or reduced-dose tacrolimus in liver transplant recipients.

The pharmacokinetics of mycophenolate mofetil (MMF) in liver transplant recipients may change because of pharmacokinetic interactions with coadministered immunosuppressants or because changes in the enterohepatic anatomy may affect biotransformation of MMF to mycophenolic acid (MPA) and enterohepatic recirculation of MPA through the hydrolysis of mycophenolate acid glucuronide to MPA in the gut. In the latter case, the choice of formulation (oral versus intravenous) could have important clinical implications. We randomized liver transplant patients (n = 60) to standard (10-15 ng/mL) or reduced (5-8 ng/mL) trough levels of tacrolimus plus intravenous MMF followed by oral MMF (1 g twice daily) with corticosteroids. Pharmacokinetic sampling was performed after the last intravenous MMF dose, after the first oral MMF dose, and at selected times over 52 weeks. The efficacy and safety of the 2 regimens were also assessed. Twenty-eight and 27 patients in the tacrolimus standard-dose and reduced-dose groups, respectively, were evaluated. No significant differences between the tacrolimus standard-dose and reduced-dose groups were seen in dose-normalized MPA values of the time to the maximum plasma concentration (1.25 versus 1.28 hours), the maximum plasma concentration (15.5 +/- 7.93 versus 13.6 +/- 7.03 microg/mL), or the area under the concentration-time curve from 0 to 12 hours (AUC(0-12); 53.0 +/- 20.6 versus 43.8 +/- 15.5 microg h/mL) at week 26 or at any other time point. No relationship was observed between the tacrolimus trough or AUC(0-12) and MPA AUC(0-12). Exposure to MPA after oral and intravenous administration was similar. Safety and efficacy were similar in the two treatment groups. In conclusion, exposure to MPA is not a function of exposure to tacrolimus. The similar safety and efficacy seen with MMF plus standard or reduced doses of tacrolimus suggest that MMF could be combined with reduced doses of tacrolimus.

AMPA and kainate receptors mediate mutually exclusive effects on GABA(A) receptor expression in cultured mouse cerebellar granule neurones.

Studies on animal models of epilepsy and cerebellar ataxia, e.g., stargazer mice (stg) have identified changes in the GABAergic properties of neurones associated with the affected brain loci. Whether these changes contribute to or constitute homeostatic adaptations to a state of altered neuronal excitability is as yet unknown. Using cultured cerebellar granule neurones from control [+/+; alpha-amino-3-hydroxyl-5-methyl-4-isoxazolepropionate receptor (AMPAR)-competent, Kainate receptor (KAR)-competent] and stg (AMPAR-incompetent, KAR-competent), we investigated whether non-NMDA receptor (NMDAR) activity regulates GABA(A) receptor (GABAR) expression. Neurones were maintained in 5 mmol/L KCl-containing basal media or depolarizing media containing either 25 mmol/L KCl or the non-NMDAR agonist kainic acid (KA) (100 micromol/L). KCl- and KA-mediated depolarization down-regulated GABAR alpha1, alpha6 and beta2, but up-regulated alpha4, beta3 and delta subunits in +/+ neurones. The KCl-evoked but not KA-evoked effects were reciprocated in stg neurones compatible with AMPAR-regulation of GABAR expression. Conversely, GABAR gamma2 expression was insensitive to KCl-mediated depolarization, but was down-regulated by KA-treatment in a 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX)-reversible manner in +/+ and stg neurones compatible with a KAR-mediated response. KA-mediated up-regulation of GABAR alpha4, beta3 and delta was inhibited by L-type voltage-gated calcium channel (L-VGCC) blockers and the Ca2+/calmodulin-dependent protein kinase inhibitor, 4-[(2S)-2-[(5-isoquinolinylsulfonyl)methylamino]-3-oxo-3-(4-phenyl-1-piperazinyl)propyl] phenyl isoquinoline sulfonic acid ester (KN-62). Up-regulation of GABAR alpha4 and beta3 was also prevented by calcineurin (CaN) inhibitors, FK506 and cyclosporin A. Down-regulation of GABAR alpha1, alpha6 and beta2 was independent of L-VGCC activity, but was prevented by inhibitors of CaN. Thus, we provide evidence that a KAR-mediated and at least three mutually exclusive AMPAR-mediated signalling mechanisms regulate neuronal GABAR expression.

Aberrant GABA(A) receptor expression in the dentate gyrus of the epileptic mutant mouse stargazer.

Stargazer (stg) mutant mice fail to express stargazin [transmembrane AMPA receptor regulatory protein gamma2 (TARPgamma2)] and consequently experience absence seizure-like thalamocortical spike-wave discharges that pervade the hippocampal formation via the dentate gyrus (DG). As in other seizure models, the dentate granule cells of stg develop elaborate reentrant axon collaterals and transiently overexpress brain-derived neurotrophic factor. We investigated whether GABAergic parameters were affected by the stg mutation in this brain region. GABA(A) receptor (GABAR) alpha4 and beta3 subunits were consistently upregulated, GABAR delta expression appeared to be variably reduced, whereas GABAR alpha1, beta2, and gamma2 subunits and the GABAR synaptic anchoring protein gephyrin were essentially unaffected. We established that the alpha4 betagamma2 subunit-containing, flunitrazepam-insensitive subtype of GABARs, not normally a significant GABAR in DG neurons, was strongly upregulated in stg DG, apparently arising at the expense of extrasynaptic alpha4 betadelta-containing receptors. This change was associated with a reduction in neurosteroid-sensitive GABAR-mediated tonic current. This switch in GABAR subtypes was not reciprocated in the tottering mouse model of absence epilepsy implicating a unique, intrinsic adaptation of GABAergic networks in stg. Contrary to previous reports that suggested that TARPgamma2 is expressed in the dentate, we find that TARPgamma2 was neither detected in stg nor control DG. We report that TARPgamma8 is the principal TARP isoform found in the DG and that its expression is compromised by the stargazer mutation. These effects on GABAergic parameters and TARPgamma8 expression are likely to arise as a consequence of failed expression of TARPgamma2 elsewhere in the brain, resulting in hyperexcitable inputs to the dentate.

Comparison of mycophenolate mofetil and azathioprine for prevention of bronchiolitis obliterans syndrome in de novo lung transplant recipients.

BACKGROUND: There are no data on the effects of mycophenolate mofetil (MMF) on the incidence of bronchiolitis obliterans syndrome (BOS) in lung-transplant patients. This study attempted to determine whether MMF reduces the incidence of BOS in de novo lung transplant recipients compared with azathioprine (AZA). METHODS: This prospective, randomized, open-label, multicenter study compared the effects of MMF with AZA in combination with induction therapy, cyclosporine (Neoral) and corticosteroids in patients receiving their first lung transplant. Primary endpoint was incidence of BOS at 3 years. Secondary endpoints were incidence of acute rejection, time to first rejection event, and survival. RESULTS: The incidence of acute rejection and the time to first rejection event at 1 and 3 years did not differ between groups (54.1% vs. 53.8% and 56.6% vs. 60.3% for MMF and AZA respectively). Survival at 1 year tended to be better in patients receiving MMF (88 vs. 80%, P = 0.07). At year 3, there was no difference in survival or in the incidence, severity or time to acquisition of BOS between the two groups. Treatment was generally well tolerated, however more patients withdrew from AZA treatment than from MMF (59.6% vs. 46.5%, P = 0.02). As a result, there was an imbalance in the observation times of the two groups (876 +/- 395 vs. 947 +/- 326 days). CONCLUSIONS: No differences were seen in the incidence of acute rejection or BOS in lung transplant recipients treated with MMF or AZA. This null result may have been influenced by the shorter observation time for AZA patients.

Pharmacokinetics and Safety of Valganciclovir in Pediatric Heart Transplant Recipients 4 Months of Age and Younger.

BACKGROUND: Valganciclovir (VGCV) effectively prevents cytomegalovirus disease in adult and pediatric solid organ transplant recipients. A dosing algorithm for VGCV for pediatric patients, based on body surface area and renal function, provides a personalized dose using age-appropriate formulations. The suitability of this dosing algorithm has not been assessed specifically in infants and neonates 4 months of age and younger receiving a solid organ transplant. METHODS: This multicenter prospective study evaluated the pharmacokinetics (PK) and safety of VGCV oral solution in 17 heart transplant recipients 4 months of age and younger who received 2 doses of VGCV on consecutive days using the pediatric dosing algorithm. Plasma concentrations of ganciclovir (GCV) were analyzed at specified times up to 24 hours post VGCV administration. RESULTS: GCV concentration data were available from 16 patients. The combined data from this study and historic study datasets were used to establish a 2-compartment population PK model with first-order formation to describe the PK of GCV after oral VGCV administration in patients across all pediatric age ranges, including those younger than 4 months of age. Estimated mean area under the curve during the 0-24 hours dosing interval for these patients was 68.1 µg·h/mL. CONCLUSIONS: The pediatric dosing algorithm for VGCV (utilizing individuals' body surface area and renal function) provides systemic GCV exposures in patients younger than 4 months that are similar to those observed in older pediatric populations. The data indicate that this dosing algorithm is appropriate across the entire pediatric age range, including this youngest age group.

Use of a pharmacophore model to discover a new class of influenza endonuclease inhibitors.

Data from both our own and literature studies of the biochemistry and inhibition of influenza virus endonuclease was combined with data on the mechanism of action and the likely active site mechanism to propose a pharmacophore. The pharmacophore was used to design a novel structural class of inhibitors, some of which were found to have activities similar to that of known influenza endonuclease inhibitors and were also antiviral in cell culture.

Incidence of cytomegalovirus UL97 and UL54 amino acid substitutions detected after 100 or 200 days of valganciclovir prophylaxis.

BACKGROUND: The IMPACT study was a randomized, double-blind study comparing 100 to 200 days of VGCV prophylaxis (900 mg once daily) in D+/R- kidney transplant recipients. Although extending the duration of prophylaxis resulted in a significant reduction in confirmed cytomegalovirus (CMV) disease (100-day: 36.8% vs 200-day: 16.1%(1)), the consequence of extending the duration of prophylaxis on the development of viral resistance remains unknown. OBJECTIVE: To determine whether extending valganciclovir prophylaxis from 100 days to 200 days increased the incidence of ganciclovir resistance. STUDY DESIGN: Genotypic analysis of CMV UL97 and UL54 was conducted on virus isolated from patients meeting the predefined resistance analysis criteria (RAC). RESULTS: A greater number of patients met the RAC in the 100 day prophylaxis arm (50/163; 31%) compared to the 200 day prophylaxis arm (22/155; 14%). Sequence data were successfully generated for all 200-day patients and 48/50 100-day patients. Three patients in each treatment arm (100 day: 3/163 (1.8%) vs 200 day: 3/155 (1.9%)) had a single known valganciclovir resistance mutation detected (100 day: UL97 gene: M460V, C592G twice; 200 day: UL97 gene: C603W, M460V and UL54 gene: P522S). Overall, a resistance mutation was more likely to be detected if the patient met the RAC during prophylaxis (5/12 (42%)) compared to post-prophylaxis (1/58 (2%)). All six patients with known ganciclovir resistance mutations cleared the virus; three cleared virus without treatment and three cleared virus following treatment. CONCLUSIONS: Extending valganciclovir prophylaxis from 100 days to 200 days did not significantly affect the incidence of ganciclovir resistance.

Incidence and characterization of cytomegalovirus resistance mutations among pediatric solid organ transplant patients who received valganciclovir prophylaxis.

BACKGROUND: Drug-resistant cytomegalovirus (CMV) infections can cause significant morbidity among high-risk transplant recipients. OBJECTIVES: The aims of this study were to determine the incidence and clinical consequences of CMV mutations conferring ganciclovir resistance in pediatric solid organ transplant (SOT) patients who received valganciclovir oral solution or tablets for prophylaxis of CMV disease. Recombinant CMV mutants were also generated to assess the role of two UL97 mutations of unknown significance. STUDY DESIGN: Genotypic resistance mutations and CMV viral load were sought in blood samples from pediatric SOT recipients who received valganciclovir prophylaxis for 100 days. Recombinant viruses containing novel CMV UL97 mutations were generated using a bacterial artificial chromosome containing the CMV genome to assess ganciclovir susceptibility. RESULTS: Overall, four known resistance UL97 mutations were observed in blood samples from 2 of 46 patients during the study with no development of CMV disease. Two UL97 changes (M615V and V466G) of unknown significance and one UL97 mutation (C603R) associated with ganciclovir resistance, but not yet confirmed by marker transfer, were also detected. Recombinant viruses containing these novel mutations were generated to assess ganciclovir susceptibility. The M615V recombinant virus was susceptible to ganciclovir while the V466G and C603R mutant viruses displayed 3.5-fold and 3.6-fold decreases in susceptibility, respectively. CONCLUSIONS: The low incidence of ganciclovir resistance-associated mutations and the absence of clinical consequences associated with drug-resistant viruses observed in this pilot study should encourage the design of larger clinical trials aimed at evaluating the efficacy of valganciclovir prophylaxis and treatment in the pediatric setting.

Recombinant phenotyping of cytomegalovirus sequence variants detected after 200 or 100 days of valganciclovir prophylaxis.

BACKGROUND: In a phase III controlled trial IMproved Protection Against Cytomegalovirus in Transplantation (IMPACT) comparing 200 with 100 days of valganciclovir prophylaxis in 318 cytomegalovirus D+/R- kidney transplant recipients, an equal number of patients (n=3 per arm) had known ganciclovir resistance mutations detected during viral breakthrough. In addition, many other viral sequence variants were observed that were of unknown significance for ganciclovir resistance. Recombinant phenotyping was performed to determine whether the previously uncharacterized genotypic changes affected ganciclovir susceptibility, especially in those receiving the longer duration of prophylaxis. METHODS: Sequences encoding individual amino acid substitutions in the UL97 kinase or UL54 DNA polymerase gene were transferred by recombination into a cloned cytomegalovirus laboratory strain, followed by reporter-based yield reduction phenotypic assay of the resulting virus for ganciclovir susceptibility. RESULTS: Twenty-six uncharacterized amino acid substitutions were detected, 2 in UL97 and 24 in UL54. All 10 substitutions in the 200-day arm and 9 of 17 substitutions in the 100-day arm (prioritized based on location and conservation) were selected for phenotyping; one substitution was detected in both subsets. Results were generated for nine of ten 200-day and eight of nine 100-day substitutions, with no substitution demonstrating a significant reduction in ganciclovir susceptibility. The two remaining amino acid substitutions, both in UL54, were not evaluated because of poor viral viability. CONCLUSION: Phenotypic evaluation of previously uncharacterized viral genotypes in the 200-day valganciclovir prophylaxis group showed no evidence of an increased incidence of genotypic ganciclovir resistance when compared with those in the 100-day prophylaxis group.

Extended valganciclovir prophylaxis in D+/R- kidney transplant recipients is associated with long-term reduction in cytomegalovirus disease: two-year results of the IMPACT study.

BACKGROUND: Whether the early reduction in cytomegalovirus (CMV) disease seen at 1 year with prolongation of antiviral prophylaxis (up to 200 days) persists in the long term is unknown. METHODS: This international, randomized, prospective, double-blind study, compared 318 CMV D+/R- kidney transplant recipients receiving valganciclovir (900 mg) once daily for up to 200 days vs. 100 days. Long-term outcomes including CMV disease, acute rejection, graft loss, patient survival, and seroconversion were assessed. RESULTS: At 2 years posttransplant, CMV disease occurred in significantly less patients in the 200- vs. the 100-day group: 21.3% vs. 38.7%, respectively (P<0.001). Between year 1 and 2, there were only 10 new cases of CMV disease; 7 in the 200-day group and 3 in the 100-day group. Patient survival was 100% in the 200-day group and 97% in the 100-day group (p=not significant). Biopsy-proven acute rejection and graft loss rates were comparable in both groups (11.6% vs. 17.2%, P=0.16, and 1.9% vs. 4.3%, P=0.22, in the 200-day vs. 100-day groups, respectively). Seroconversion was delayed in the 200-day group but was similar to the 100-day group by 2 years posttransplant (IgM or IgG seroconversion; 55.5% in the 200-day group vs. 62.0% in the 100-day group at 2-years; P=0.26). Assessment of seroconversion at the end of prophylaxis was of limited utility for predicting late-onset CMV disease. CONCLUSION: Extending valganciclovir prophylaxis from 100 to 200 days is associated with a sustained reduction in CMV disease up to 2 years posttransplant.

GABAA alpha6-containing receptors are selectively compromised in cerebellar granule cells of the ataxic mouse, stargazer.

Stargazer mice fail to express the gamma2 isoform of transmembrane alpha-amino-3-hydroxyl-5-methyl-4-isoxazolepropionate (AMPA) receptor regulatory proteins that has been shown to be absolutely required for the trafficking and synaptic targeting of excitatory AMPA receptors in adult murine cerebellar granule cells. Here we show that 30 +/- 6% fewer inhibitory gamma-aminobutyric acid, type A (GABA(A)), receptors were expressed in adult stargazer cerebellum compared with controls because of a specific loss of GABA(A) receptor expression in the cerebellar granule cell layer. Radioligand binding assays allied to in situ immunogold-EM analysis and furosemide-sensitive tonic current estimates revealed that expression of the extrasynaptic (alpha6betaxdelta) alpha6-containing GABA(A) receptor were markedly and selectively reduced in stargazer. These observations were compatible with a marked reduction in expression of GABA(A) receptor alpha6, delta (mature cerebellar granule cell-specific proteins), and beta3 subunit expression in stargazer. The subunit composition of the residual alpha6-containing GABA(A) receptors was unaffected by the stargazer mutation. However, we did find evidence of an approximately 4-fold up-regulation of alpha1betadelta receptors that may compensate for the loss of alpha6-containing GABA(A) receptors. PCR analysis identified a dramatic reduction in the steady-state level of alpha6 mRNA, compatible with alpha6 being the primary target of the stargazer mutation-mediated GABA(A) receptor abnormalities. We propose that some aspects of assembly, trafficking, targeting, and/or expression of extrasynaptic alpha6-containing GABA(A) receptors in cerebellar granule cells are selectively regulated by AMPA receptor-mediated signaling.

Differential cell surface expression of GABAA receptor alpha1, alpha6, beta2 and beta3 subunits in cultured mouse cerebellar granule cells influence of cAMP-activated signalling.

In this study we have used mature, primary cultured mouse cerebellar granule cells (CGCs) to initiate our studies on the mechanisms governing neuronal trafficking of GABAA receptors (GABARs). Initially the steady-state distribution of GABAR alpha1, alpha6, beta2 and beta3 subunits between the cell surface and cell interior was quantified. Cell surface proteins were modified with a membrane-impermeable cross-linking agent, bis(sulfosuccinimidyl)suberate (BS3) or the proteolytic enzyme, chymotrypsin. The proportion of unmodified (intracellular) and modified (cell surface) subunits was quantified by immunoblotting. We found that 51% of alpha6, 74% of alpha1, and 83% of beta2/3 were expressed at the cell surface, thus identifying a sizeable intracellular pool of alpha6 in contrast to the low levels of intracellular alpha1 and beta2/3. Chronic activation of protein kinase A (PKA) in CGCs in vitro, post-transcriptionally up-regulated expression of alpha1, beta2 and beta3 but not beta6. This was paralleled by an increase in the BZ-S subtype of [3H]Ro154513 binding sites. GABAR alpha1 was increased at the cell surface and in the cell interior, beta2 was increased almost exclusively at the cell surface whilst beta3 was increased almost exclusively in the cell interior. The intracellular pool of alpha6 was not affected. Thus, GABAR subunits are subject to differentially regulated trafficking, affording yet greater scope for GABAR diversity and plasticity.

Microtubule-associated protein light chain 2 is a stargazin-AMPA receptor complex-interacting protein in vivo.

The ataxic mutant mouse stargazer is a null mutant for stargazin, a protein involved in the regulation of cell surface trafficking and synaptic targeting of AMPA receptors. The extreme C terminus of stargazin (sequence, -TTPV), confers high affinity for PDZ domain-containing proteins e.g. PSD-95. Interaction with PDZ proteins enables stargazin to fulfill its role as an AMPA receptor synaptic targeting molecule but is not essential for its ability to influence AMPA receptor trafficking to the neuronal cell surface. Using the yeast-two hybrid approach we screened for proteins that interact with the intracellular C-terminal tail of stargazin. Positive interactors included PDZ domain-containing proteins e.g. SAP97, SAP102, and PIST. Interestingly, light chain 2 of microtubule-associated protein 1 (LC2), which does not contain a PDZ domain, was also a strong interactor. This was shown to be a direct interaction that occurred upstream of the -TTPV sequence of stargazin. Immunoprecipitations of Triton X-100 soluble cerebellar extracts revealed that LC2 is pulled down not only by anti-stargazin antibodies but also anti-GluR2 antibodies suggesting that stargazin and AMPA receptor subunits associate with LC2. Immunopurified full-length, native stargazin was shown to co-associate not only with GluR2 in vivo but also with full-length, native LC2. Indeed, LC2 co-associates with stargazin when part of a tripartite complex comprising LC2-stargazin-GluR2. Since this complex was extracted using Triton X-100 and was devoid of PSD95, SAP97, and actin we postulate that LC2 is involved in trafficking of AMPA receptors in cerebellar neurons before they are anchored at the synapse.