Pharmacokinetics and Safety Study of HN0141, a Novel Anti-Human Cytomegalovirus Inhibitor, in Healthy Volunteers

HN0141 is a human cytomegalovirus (HCMV) DNA terminase complex inhibitor being developed for prophylaxis and/or preemptive treatment of HCMV infection and diseases. This study evaluated the safety, tolerability, and pharmacokinetics (PK) of HN0141, following oral administration in healthy volunteers. The double-blind, placebo-controlled Phase 1 study comprised Part 1, an escalating, single-dose study involving 50-, 100-, 200-, 300-, 400-, and 525-mg doses; and Part 2, a multiple-dose study over 7 days involving 50-, 100-, 200-, and 400-mg twice-daily doses. HN0141 was rapidly absorbed following oral doses, with median time to maximum concentration achieved within 1-2 hours across all doses. At doses ranging from 50 to 100 mg, the PK profile was reasonably linear, while at doses above 200 mg, the PK profile was more than proportional. The predicted therapeutic dose would be 50-200 mg twice daily, which is at a reasonable linear PK range. All exposures tested (up to 525-mg single dose and 400-mg twice-daily multiple doses) were within the no-observed-adverse-effect level defined in animal toxicity studies. There was a mild accumulation on systemic exposure at steady state, which was achieved within 72 hours of multiple twice-daily dosing. No serious or severe adverse events were reported. HN0141's PK profile favors the twice-daily dosing, which gives a smaller concentration variation during the treatment, and thus could bring a better treatment effect with sufficient convenience. These Phase 1 data in safety and PK profile warrant further drug development in both preemptive and prophylactic treatment in patients with HCMV.

The Importance of Drug Exposure in the Development of Cytomegalovirus Resistance

Human cytomegalovirus (CMV) is a widespread pathogen which remains asymptomatic in healthy individuals. However, CMV disease can be life-threatening in immunocompromised individuals, particularly in transplant patients. This disease is routinely managed by antiviral agents including (val)ganciclovir, foscarnet, cidofovir, letermovir, and maribavir. Subtherapeutic antiviral drug exposure is a common occurrence and can lead to drug-resistant CMV development, a key contributor to disease progression. Breakthrough CMV often results in graft loss, end-organ failure, or death. By optimising intracellular exposure levels of antiviral therapies, it may be possible to improve patient outcomes. Therefore, this review aims to explore the relationship between antiviral exposure and the development of drug-resistant CMV. There are several challenges to achieving optimal concentrations of current and novel CMV therapies. Narrow therapeutic indices and toxicity profiles of current CMV therapeutics contribute to their subtherapeutic exposure and hence suboptimal clinical outcomes. Alternately, novel antivirals such as letermovir and maribavir offer improved pharmacokinetic profiles. However, these agents are associated with rapid resistance development. Overall, a distinct gap exists in understanding the relationship between antiviral exposure and resistance development. As a result, current clinical markers used to predict clinical efficacy lack reliability. In future, resistance development in relation to drug exposure should be included as a clinical trial endpoint to gain understanding of exposure-resistance relationships. With solid knowledge of these relationships, more predictive in vitro and in vivo markers of clinical efficacy can be identified. Additionally, pharmacokinetic-pharmacodynamic models and combination therapies should be further explored in to improve the management of CMV.

Characterization of human cytomegalovirus infection dynamics in human microglia

Human cytomegalovirus (HCMV) is a β-herpesvirus that establishes asymptomatic infections in immunocompetent individuals but can cause severe or even life-threatening symptoms in immunocompromised patients. HCMV can replicate in a wide variety of cells through the engagement of diverse cell factors with the viral envelope protein gH/gL/gO (trimer) or gH/gL/UL128/UL130/UL131a (pentamer), allowing for systemic spread within the human host. This study explores HCMV infection tropism and dynamics in human microglia, demonstrating the susceptibility of microglia to both clinical and laboratory HCMV strains, albeit with lower efficacy for the laboratory strain, implying that both the gH/gL-trimer and -pentamer can mediate virus entry in microglia. The importance of the gH/gL pentamer for virus entry was demonstrated by the inhibition of virus infection upon pre-incubation with a soluble neuropilin-2 (NRP-2) entry factor. Further, we demonstrated that HCMV infection can be effectively inhibited by monoclonal antibodies specific for the gH/gL complexes and HCMV hyperimmunoglobulin. Lastly, we report that microglia infection can be prevented by newly characterized chemical entry inhibitors. Altogether, these findings underscore the potential of microglia as valuable models for studying HCMV neurotropism and strategies to block virus infection in cells that can impact neurological disorders.

Antiviral therapy for cytomegalovirus retinitis: A systematic review and meta-analysis

Cytomegalovirus retinitis (CMVR) is a significant cause of blindness in patients with advanced acquired immunodeficiency syndrome (AIDS). There are no established guidelines for its treatment, resulting in varied antiviral approaches. We pooled data from 59 studies (4501 patients) to evaluate treatment variations and outcomes (CRD42022321088). Overall pooled estimates showed visual acuity improvement at 18 % (95 % CI: 7-41 %), inflammation resolution at 90 % (95 % CI: 81-95 %), retinal detachment at 11 % (95 % CI: 8-14 %), and recurrence at 19 % (95 % CI: 11-31 %). The main antiviral treatment approaches identified were: (1) intravenous antivirals alone in 33 studies, (2) intravitreal antivirals alone in 26 studies, (3) oral antivirals alone in 3 studies, and (4) a combination of systemic (oral or intravenous[IV]) and intravitreal antivirals in 7 studies, with varying schemes and durations. Ganciclovir was the predominant antiviral, with intravenous administration being the most reported (in 23 studies), followed by intravitreal administration (in 20 studies). While visual acuity improvement was comparable, inflammation resolution tended to be higher with intravitreal than with IV antivirals, though not statistically significant (88 %, 95 % CI: 69-96 % vs 75 %, 95 % CI: 35-94 %, p = 0.38). Retinitis progression rate for IV ganciclovir was lower than for those without ganciclovir. Inflammation recurrence was significantly lower in antiretroviral (ART)-treated compared to non-ART-treated HIV/AIDS patients (10 % (95 % CI: 4-20 %) vs 33 % (95 % CI: 19-50 %), p < 0.01). Neutropenia, particularly with ganciclovir, was the most reported adverse effect (up to 50 %).

Cytomegalovirus-associated panenteritis in an immunocompetent 60-year-old woman treated with oral valganciclovir: a case report

Cytomegalovirus (CMV) infection typically affects immunocompromised individuals. However, CMV-associated enteritis involving the entire small intestine is rare in immunocompetent patients. We report a case of a 60-year-old immunocompetent woman with a history of diabetes mellitus who presented with diarrhea for 3 weeks. Abdominal computed tomography and stool tests revealed panenteritis accompanied by protein-losing enteropathy. Enteroscopy revealed ulcerative mucosa throughout the small intestine, and subsequent biopsies confirmed CMV-associated enteritis. Initial treatment with intravenous ganciclovir was complicated by pancytopenia, leading to its discontinuation and a switch to oral valganciclovir. This adjustment led to significant clinical improvement and symptom resolution. This case highlights the importance of considering CMV-associated enteritis in immunocompetent patients presenting with unexplained gastrointestinal symptoms and demonstrates the effectiveness of oral valganciclovir following ganciclovir-induced pancytopenia.

Steroid-tacrolimus drug-drug interaction and the effect of CYP3A genotypes

AIMS

Tacrolimus, metabolized by CYP3A4 and CYP3A5 enzymes, is susceptible to drug-drug interactions (DDI). Steroids induce CYP3A genes to increase tacrolimus clearance, but the effect is variable. We hypothesized that the extent of the steroid-tacrolimus DDI differs by CYP3A4/5 genotypes.

METHODS

Kidney transplant recipients (n = 2462) were classified by the number of loss of function alleles (LOF) (CYP3A5*3, *6 and *7 and CYP3A4*22) and steroid use at each tacrolimus trough in the first 6 months post-transplant. A population pharmacokinetic analysis was performed by nonlinear mixed-effect modelling (NONMEM) and stepwise covariate modelling to define significant covariates affecting tacrolimus clearance. A stochastic simulation was performed and translated into a Shiny application with the mrgsolve and Shiny packages in R.

RESULTS

Steroids were associated with modestly higher (3%-11.8%) tacrolimus clearance. Patients with 0-LOF alleles receiving steroids showed the greatest increase (11.8%) in clearance compared to no steroids, whereas those with 2-LOFs had a negligible increase (2.6%) in the presence of steroids. Steroid use increased tacrolimus clearance by 5% and 10.3% in patients with 1-LOF and 3/4-LOFs, respectively.

CONCLUSIONS

Steroids increase the clearance of tacrolimus but vary slightly by CYP3A genotype. This is important in individuals of African ancestry who are more likely to carry no LOF alleles, may more commonly receive steroid treatment, and will need higher tacrolimus doses.

Differences in safety profiles of anti-herpesvirus medications: a real-world pharmacovigilance study based on the FAERS database

BACKGROUND

Anti-herpesvirus drug safety profiles have not been systematically compared. Understanding variations in adverse events (AEs) could provide reference for rational clinical use.

METHODS

We collected data on acyclovir, ganciclovir, valaciclovir, and foscarnet from the FDA Adverse Event Reporting System (FAERS) database from Q1 2004 to Q3 2023. Disproportionality analyses were conducted to evaluate the risk of AEs.

RESULTS

All drugs exhibited significant associations with hematotoxicity, with ganciclovir and foscarnet being more myelosuppressive. The correlation with renal impairment ranked as follows: foscarnet, ganciclovir, valaciclovir, and acyclovir (ROR = 16.72, 7.06, 3.51, and 2.02, respectively). Regarding hepatotoxicity, ganciclovir was associated with acute-on-chronic liver failure (ROR = 52.83), and foscarnet was associated with fulminant hepatitis (ROR = 49.91). In the nervous system, acyclovir showed the highest intensity of neurotoxicity (ROR = 14.95). Valaciclovir ranked first in toxic encephalopathy (ROR = 64.70). Foscarnet showed the highest intensity of status epilepticus (ROR = 6.45). Besides, acyclovir showed the strongest association with severe cutaneous adverse reactions (SCARs).

CONCLUSIONS

Our study revealed differences in safety profiles of four anti-herpesvirus medications. Ganciclovir exhibited the highest risk of hematotoxicity but appeared relatively safe in seizures and SCARs. Foscarnet was more likely to induce nephrotoxicity, seizures, and electrolyte imbalances than others. Acyclovir and valaciclovir were strongly associated with plasmacytosis, neurotoxicity, and SCARs.

Adenovirus- and cytomegalovirus-specific adoptive T-cell therapy in the context of hematologic cell transplant or HIV infection - A single-center experience

BACKGROUND

Reactivation of viral infections, in particular cytomegalovirus (CMV) and adenovirus (ADV), cause morbidity and non-relapse-mortality in states of immune deficiency, especially after allogeneic hematopoietic cell transplantation (allo-HCT). Against the background of few available pharmacologic antiviral agents, limited by toxicities and resistance, adoptive transfer of virus-specific T-cells (VST) is a promising therapeutic approach.

METHODS

We conducted a single-center retrospective analysis of adult patients treated with ADV- or CMV-specific T-cells in 2012-2022. Information was retrieved by review of electronic health records. Primary outcome was a response to VST by decreasing viral load or clinical improvement. Secondary outcomes included overall survival and safety of VST infusion, in particular association with graft-versus-host disease (GVHD).

RESULTS

Ten patients were included, of whom four were treated for ADV, five for CMV, and one for ADV-CMV-coinfection. Cells were derived from stem cell donors (6/10) or third-party donors (4/10). Response criteria were met by six of 10 patients (4/4 ADV, 2/5 CMV, and 0/1 ADV-CMV). Overall survival was 40%. No infusion related adverse events were documented. Aggravation of GVHD after adoptive immunotherapy was observed in two cases, however in temporal association with a conventional donor lymphocyte infusion and a stem cell boost, respectively.

CONCLUSION

In this cohort, CMV- and ADV-specific T-cell therapy appear to be safe and effective. We describe the first reported case of virus-specific T-cell therapy for CMV reactivation not associated with transplantation but with advanced HIV infection. This encourages further evaluation of adoptive immunotherapy beyond the context of allo-HCT.

Hematological Complications of Human Immunodeficiency Virus (HIV) Infection: An Update From an HIV-Endemic Setting

Medical professionals, particularly in regions with a high burden of human immunodeficiency virus (HIV), should be alert to the hematological complications of HIV, which may include cytopenias, malignancy, and coagulation disturbances. Patients may present with these conditions as the first manifestation of HIV infection. Hematological abnormalities are often multifactorial with opportunistic infections, drugs, malignancy, and HIV infection itself contributing to the clinical presentation, and the diagnosis should consider all these factors. Life-threatening hematological complications requiring urgent diagnosis and management include thrombotic thrombocytopenic purpura, superior mediastinal syndrome, spinal cord compression, and tumor lysis syndrome due to aggressive lymphoma. Antiretroviral therapy is the therapeutic backbone, including for patients with advanced HIV, in addition to specific therapy for the complication. This article reviews the impact of HIV on the hematological system and provides a clinical and diagnostic approach, including the role of a bone marrow biopsy, focusing on perspectives from sub-Saharan Africa.

Cytomegalovirus related hospitalization costs among hematopoietic stem cell and solid organ transplant recipients treated with maribavir versus investigator-assigned therapy: A US-based study

BACKGROUND

Cytomegalovirus (CMV) infections among hematopoietic stem cell transplant (HSCT) and solid organ transplant (SOT) recipients impose a significant health care resource utilization (HCRU)-related economic burden. Maribavir (MBV), a novel anti-viral therapy (AVT), approved by the United States Food and Drug Administration for post-transplant CMV infections refractory (with/without resistance) to conventional AVTs has demonstrated lower hospital length of stay (LOS) versus investigator-assigned therapy (IAT; valgancilovir, ganciclovir, foscarnet, or cidofovir) in a phase 3 trial (SOLSTICE). This study estimated the HCRU costs of MBV versus IAT.

METHODS

An economic model was developed to estimate HCRU costs for patients treated with MBV or IAT. Mean per-patient-per-year (PPPY) HCRU costs were calculated using (i) annualized mean hospital LOS in SOLSTICE, and (ii) CMV-related direct costs from published literature. Probabilistic sensitivity analysis with Monte-Carlo simulations assessed model robustness.

RESULTS

Of 352 randomized patients receiving MBV (n = 235) or IAT (n = 117) for 8 weeks in SOLSTICE, 40% had HSCT and 60% had SOT. Mean overall PPPY HCRU costs of overall hospital-LOS were $67,205 (95% confidence interval [CI]: $33,767, $231,275) versus $145,501 (95% CI: $62,064, $589,505) for MBV and IAT groups, respectively. Mean PPPY ICU and non-ICU stay costs were: $32,231 (95% CI: $5,248, $184,524) versus $45,307 (95% CI: $3,957, $481,740) for MBV and IAT groups, and $82,237 (95% CI: $40,397, $156,945) MBV versus $228,329 (95% CI: $94,442, $517,476) for MBV and IAT groups, respectively. MBV demonstrated cost savings in over 99.99% of simulations.

CONCLUSIONS

This analysis suggests that Mean PPPY HCRU costs were 29%-64% lower with MBV versus other-AVTs.

Antimicrobials in patients with hematologic malignancies and recipients of hematopoietic cell transplantation and other cellular therapies

BACKGROUND

Appropriate use of antimicrobials for hematologic malignancy, hematopoietic stem cell transplant recipients, and other cellular therapies is vital, with infection causing significant morbidity and mortality in this unique population of immunocompromised hosts. However, often in this population the choice and management of antimicrobial therapy is complex. When selecting an antimicrobial agent, key considerations include the need for dose adjustments due to renal or hepatic impairment, managing drug interactions, the potential for additive drug toxicity among those receiving polypharmacy and therapeutic drug monitoring. Other factors include leveraging pharmacodynamic principles to enable optimization of directed therapy against challenging pathogens, as well as judicious use of antimicrobials to limit drug resistance and adverse drug reactions.

SUMMARY

This review summarizes the clinical considerations for commonly used antimicrobials in this setting, including antibacterial, antiviral, and antifungal agents.

Third-Party and Patient-Specific Donor-Derived Virus-Specific T Cells Demonstrate Similar Efficacy and Safety for Management of Viral Infections after Hematopoietic Stem Cell Transplantation in Children and Young Adults

Infections with double-stranded DNA viruses are a common complication after hematopoietic stem cell transplantation (HSCT) and cause significant morbidity and mortality in the post-transplantation period. Both donor-derived (DD) and third-party (TP) virus-specific T cells (VSTs) have shown efficacy and safety in viral management following HSCT in children and young adults. Owing to a greater degree of HLA matching between the recipient and stem cell donor, DD VSTs potentially persist longer in circulation compared to TP VSTs, because they are collected from a well-matched donor. However, TP VSTs are more easily accessible, particularly for smaller transplantation centers that do not have VST manufacturing capabilities, and more economical than creating a customized product for each transplant recipient. We conducted the present study to compare clinical efficacy and safety outcomes for DD VSTs and TP VSTs in a large cohort of pediatric and young adult HSCT recipients and to determine whether DD VSTs are associated with improved outcomes owing to potentially longer persistence in the recipient's circulation. This retrospective cohort study included 145 patients who received VSTs at Cincinnati Children's Hospital Medical Center (CCHMC) between 2017 and 2021 for the treatment of adenovirus, BK virus, cytomegalovirus, and/or Epstein-Barr virus. Viruses were detected using quantitative polymerase chain reaction. Patients received VSTs on a DD (NCT02048332) or TP (NCT02532452) protocol, and VST products for both protocols were manufactured in an identical fashion. The primary study outcome was clinical response to VSTs, evaluated 4 weeks after VST administration, defined as decrease in viral load to under the inclusion thresholds, or resolution of symptoms of invasive viral infection, without the need for additional conventional antiviral medication following VST administration. Secondary outcomes included graft-versus-host-disease, transplant-associated thrombotic microangiopathy, renal function, hospital length of stay, and overall survival at 30 days and 100 days after VST administration and 1 year after HSCT. Statistical analysis was performed using the Fisher exact test or chi-square test. An unpaired t test was used to compare continuous variables. The study group comprised 77 patients in the DD cohort and 68 patients in the TP cohort. Eighteen patients in the TP cohort underwent HSCT at CCHMC, and the other 50 underwent HSCT at other institutions and presented to CCHMC solely for VST administration. There was no statistically significant difference in clinical response rates between DD and TP cohorts (65.6% versus 62.7%; odds ratio [OR], 1.162; 95% confidence interval [CI], .619 to 2.164; P = .747). There were no significant differences in secondary outcomes between the 2 cohorts. The percentage of patients requiring multiple infusions for a clinical response did not differ significantly between the DD and TP cohorts (38.2% versus 32.5%; OR, .780; 95% CI, .345 to 1.805; P = .666). We found no significant difference in clinical response rate between DD VSTs and TP VSTs and a similar safety profile. Our data suggest that TP VSTs may be sufficient to control viral infection until immune reconstitution occurs despite the potential for more rapid VST clearance compared to DD VSTs. The lack of significant differences between DD VSTs and TP VSTs is an important finding, indicating that it is not necessary for every transplant center to manufacture customized DD VSTs, and that TP VSTs are a satisfactory substitute.

New Perspectives on Antimicrobial Agents: Maribavir

Maribavir was approved by the U.S. Food and Drug Administration in November 2021 for the treatment of adult and pediatric patients with post-transplant cytomegalovirus (CMV) infection/disease that is refractory to treatment (with or without genotypic resistance) with ganciclovir, valganciclovir, cidofovir, or foscarnet. Maribavir is an oral benzimidazole riboside with potent and selective multimodal anti-CMV activity. It utilizes a novel mechanism of action which confers activity against CMV strains that are resistant to traditional anti-CMV agents, and also offers a more favorable safety profile relative to the dose-limiting side effects of previously available therapies. Maribavir was initially studied as an agent for CMV prophylaxis in solid organ and hematopoietic stem cell recipients, but initial phase III trials failed to meet clinical efficacy endpoints. It has been more recently studied as a therapeutic agent at higher doses for refractory-resistant (R-R) CMV infections with favorable outcomes. After an overview of maribavir's chemistry and clinical pharmacology, this review will summarize clinical efficacy, safety, tolerability, and resistance data associated with maribavir therapy.

Scheduled administration of virus-specific T cells for viral prophylaxis after pediatric allogeneic stem cell transplant

Infections with double-stranded DNA viruses are a significant cause of morbidity and mortality in pediatric patients following allogeneic hematopoietic stem cell transplantation (HSCT). Virus-specific T-cell therapies (VSTs) have been shown to be an effective treatment for infections with adenovirus, BK virus, cytomegalovirus (CMV), and Epstein-Barr virus (EBV). To date, prophylactic regimens to prevent or mitigate these infections using conventional antiviral medications provide suboptimal response rates. Here we report on a clinical trial (NCT03883906) performed to assess the feasibility of rapid manufacturing and early infusion of quadrivalent VSTs generated from stem cell donors ("donor-derived VSTs") into allogeneic HSCT recipients with minimal or absent viremia. Patients were eligible to receive scheduled VSTs as early as 21 days after stem cell infusion. Twenty-three patients received scheduled VSTs. Twenty of 23 patients had no viremia at the time of infusion, while 3 patients had very low-level BK viremia. Two developed clinically significant graft-versus-host disease (GVHD), although this incidence was not outside of expected incidence early after HSCT, and both were successfully treated with systemic corticosteroids (n = 2). Five patients were deemed treatment failures. Three developed subsequent significant viremia/viral disease (n = 3). Eighteen patients did not fail treatment, 7 of whom did not develop any viremia, while 11 developed low-level, self-limited viremia that resolved without further intervention. No infusion reactions occurred. In conclusion, scheduled VSTs appear to be safe and potentially effective at limiting serious complications from viral infections after allogeneic transplantation. A randomized study comparing this scheduled approach to the use of VSTs to treat active viremia is ongoing.

The Effect of Oral Letermovir Administration on the Pharmacokinetics of a Single Oral Dose of P-Glycoprotein Substrate Digoxin in Healthy Volunteers

Letermovir is a human cytomegalovirus (CMV) terminase inhibitor approved in the United States, Canada, Japan, and the European Union for prophylaxis of CMV infection and disease in CMV-seropositive, allogeneic, hematopoietic stem-cell transplant recipients. In vitro, letermovir is a substrate and potential modulator of P-glycoprotein. The potential of letermovir to alter the pharmacokinetics of digoxin (a P-glycoprotein substrate) upon coadministration in healthy subjects was therefore investigated in a phase 1 trial (EudraCT: 2011-004516-39). Oral letermovir 240 mg was administered twice daily for 12 days with a single oral digoxin 0.5-mg dose on day 7; after a washout period, oral digoxin 0.5 mg was administered on day 35 (sequence 1). The period order was reversed after a 28-day washout for sequence 2. Pharmacokinetics and safety were evaluated. The presence of steady-state letermovir reduced digoxin area under the plasma concentration-time curve from administration until last quantifiable measurement by 12% and maximum plasma concentration by 22% compared with digoxin alone; digoxin half-life and elimination rate remained similar in both conditions. The between-subject variability of digoxin maximum plasma concentration was higher with letermovir than without (42% vs 31%) and similar for digoxin area under the plasma concentration-time curve in both periods. No specific safety or tolerability concerns were identified. Overall, letermovir had no clinically relevant effect on concomitant administration with digoxin.

Pharmacokinetics and Safety of Letermovir and Midazolam Coadministration in Healthy Subjects

Letermovir is a human cytomegalovirus (CMV) terminase inhibitor for the prophylaxis of CMV infection and disease in allogeneic hematopoietic stem-cell transplant recipients. In vitro studies have identified letermovir as a potential cytochrome P450 (CYP) 3A inhibitor. Thus, the effect of letermovir on the CYP3A isoenzyme-specific probe drug midazolam was investigated in a phase 1 trial. Healthy female subjects received single-dose intravenous (IV; 1 mg) and oral (2 mg) midazolam on days -4 and -2, respectively. Letermovir 240 mg once daily was administered on days 1 to 6, and further single doses of midazolam 1 mg IV and oral midazolam 2 mg were administered on days 4 and 6, respectively. Pharmacokinetics, tolerability, and safety were monitored throughout the trial. Following coadministration with letermovir, the least square means ratio for maximum plasma concentration and area under the plasma concentration-time curve from time 0 to the last measurable concentration was 172.4% and 225.3%, respectively, for oral midazolam, and 105.2% and 146.6%, respectively, for midazolam IV. The area under the plasma concentration-time curve from time 0 to the last measurable concentration ratio of midazolam to 1-hydroxymidazolam increased slightly in the presence of letermovir following IV (8.8-13.1; 49% increase) and oral (3.3-5.3; 59% increase) midazolam. Letermovir reached steady state, on average, by days 5 to 6. All treatments were generally well tolerated. Letermovir demonstrated moderate CYP3A inhibition.

Cytomegalovirus retinitis in patients of non-Hodgkin's lymphoma: clinical presentations and outcomes

Background

Cytomegalovirus (CMV) retinitis in patients with Non-Hodgkin’s Lymphoma (NHL) can occur even in the presence of high CD 4 counts and can behave differently when compared to CMV retinitis in human immunodeficiency (HIV) patients. It, therefore, becomes important to understand its varied presentations and the challenges in management of these cases. The aim of this study was to analyse the various patterns of presentations and outcomes of CMV Retinitis in patients with NHL.

Study design

A retrospective chart review of seven eyes of four patients of NHL presenting with CMV retinitis between June 2017 and May 2020 was done.

Methods

Clinical patterns of CMV Retinitis, CD4 counts at the time of presentation and the duration of treatment along with recurrences and time for recurrence of retinitis were assessed.

Results

Granular or indolent retinitis (6 out of 7 eyes) was the commonest form of CMV retinitis in patients of NHL. Three patients had a presenting CD4 count above 150 cells/mm³ and none of them were below 50 cells/mm³. Floaters were the commonest presenting complaint. All patients had vitritis and majority of the patients (3 out of 4) had anterior chamber (AC) inflammation. Two out of the 4 patients had a recurrence (mean time 33.8 days) after stopping the maintenance phase of ganciclovir and one patient had significant myelosuppression related to oral valganciclovir which required discontinuation of the drug.

Conclusion

CMV retinitis in NHL patients is usually of an indolent or granular type and can occur even in the presence of high CD4 counts as compared to patients with HIV. These patients may require a long term maintenance in view of frequent recurrences after discontinuation of treatment.

Pediatric onco-nephrology: time to spread the word : Part I: early kidney involvement in children with malignancy

Onco-nephrology has been a growing field within the adult nephrology scope of practice. Even though pediatric nephrologists have been increasingly involved in the care of children with different forms of malignancy, there has not been an emphasis on developing special expertise in this area. The fast pace of discovery in this field, including the development of new therapy protocols with their own kidney side effects and the introduction of the CD19-targeted chimeric antigen receptor T cell (CAR-T) therapy, has introduced new challenges for general pediatric nephrologists because of the unique effects of these treatments on the kidney. Moreover, with the improved outcomes in children receiving cancer therapy come an increased number of survivors at risk for chronic kidney disease related to both their cancer diagnosis and therapy. Therefore, it is time for pediatric onco-nephrology to take its spot on the expanding subspecialties map in pediatric nephrology.

Is It Feasible to Use CMV-Specific T-Cell Adoptive Transfer as Treatment Against Infection in SOT Recipients?

During the last decade, many studies have demonstrated the role of CMV specific T-cell immune response on controlling CMV replication and dissemination. In fact, it is well established that transplanted patients lacking CMV-specific T-cell immunity have an increased occurrence of CMV replication episodes and CMV-related complications. In this context, the use of adoptive transfer of CMV-specific T-cells has been widely investigated and applied to Hematopoietic Stem Cell Transplant patients and may be useful as a therapeutic alternative, to reconstitute the CMV specific T-cell response and to control CMV viremia in patients receiving a transplantation. However, only few authors have explored the use of T-cell adoptive transfer in SOT recipients. We propose a novel review in which we provide an overview of the impact of using CMV-specific T-cell adoptive transfer on the control of CMV infection in SOT recipients, the different approaches to stimulate, isolate and expand CMV-specific T-cells developed over the years and a discussion of the possible use of CMV adoptive cellular therapy in this SOT population. Given the timeliness and importance of this topic, we believe that such an analysis will provide important insights into CMV infection and its treatment/prevention.

Cytomegalovirus retinitis in a patient of granulomatosis with polyangiitis on long-term immunosuppressants

A 69-year-old male patient presented to the retina clinic with a sudden decrease in vision in his right eye since 1 day. He was a known case of granulomatosis with polyangiitis and was on systemic immunosuppression for the past 3 years. The best-corrected visual acuity (BCVA) in his right eye was 20/60 and he has no perception of light in the left eye. Fundus examination revealed the presence of retinitis lesions in the right eye and total optic atrophy in the left eye. A vitreous biopsy was done and the PCR was found to be positive for cytomegalovirus (CMV). He was treated with intravitreal ganciclovir injections. Subsequently, the retinitis lesions regressed and BCVA in the right eye improved to 20/40.This case report elaborates on the risks of the development of opportunistic ocular infections in patients receiving long-term systemic immunosuppressants and the need for regular ocular examinations in such cases.

Population pharmacokinetics of letermovir following oral and intravenous administration in healthy participants and allogeneic hematopoietic cell transplantation recipients

Letermovir is indicated for prophylaxis of cytomegalovirus infection and disease in allogeneic hematopoietic stem cell transplant (HSCT) recipients. Two‐stage population pharmacokinetic (PK) modeling of letermovir was conducted to support dose rationale and evaluate the impact of intrinsic/extrinsic factors. Data from healthy phase I study participants over a wide dose range were modeled to evaluate the effects of selected intrinsic factors, including pharmacogenomics; next, phase III HSCT‐recipient data at steady‐state following clinical doses were modeled. The model in HSCT recipients adequately described letermovir PK following both oral or i.v. administration, and was consistent with the healthy participant model at steady‐state clinical doses. Intrinsic factor effects were not clinically meaningful. These staged analyses indicate that letermovir PK in HSCT recipients and healthy participants differ only with respect to bioavailability and absorption rate. The HSCT recipient model was suitable for predicting exposure for exposure–response analysis supporting final dose selection.

Recent developments in antimicrobial therapy for gastrointestinal infections

PURPOSE OF REVIEW

This focused, narrative review summarizes human clinical trial data for direct-acting antimicrobials in development for the treatment of gastrointestinal infections that were published in the past 18 months (1 January 2019 to 30 June 2020).

RECENT FINDINGS

Antimicrobial agents for Clostridioides difficile infection (n = 6), cryptosporidiosis (n = 1), cytomegalovirus infection (n = 3) and Helicobacter pylori infection (n = 1) have completed and/or are undergoing human clinical trials.

SUMMARY

Although this review highlights significant advances in four disease states, many common gastrointestinal pathogens have no antimicrobials in human clinical trials, emphasizing the need for continued prioritization in this field of study.

"Mini" bank of only 8 donors supplies CMV-directed T cells to diverse recipients

Cytomegalovirus (CMV) infections remain a major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT), and standard antiviral therapies are associated with significant side effects and development of drug-resistant mutants. Adoptively transferred donor-derived CMV-specific T cells (CMVSTs) can provide an alternative treatment modality with few side effects but are not widely available due to their patient-specific nature. Here we report the establishment and use of a bank of CMVSTs derived from just 8 CMV-seropositive donors, with HLA types representing the diverse US population, as an "off-the-shelf" therapy to treat drug-refractory infections. To date, we have screened 29 patients for study participation and identified a suitable line, with ≥2 of 8 shared HLA antigens, for 28 (96.6%) patients with a median of 4 shared HLA antigens. Of these, 10 patients with persistent/refractory CMV infections or disease were eligible for treatment; a single infusion of cells produced 3 partial responses and 7 complete responses, for a cumulative response rate of 100% (95% confidence interval, 69.2-100) with no graft-versus-host disease, graft failure, or cytokine release syndrome. Potential wider use of the tested CMVSTs across transplant centers is made more feasible by our ability to produce sufficient material to generate cells for >2000 infusions from a single donor collection. Our data indicate that a "mini" bank of CMVSTs prepared from just 8 well-chosen third-party donors can supply the majority of patients with an appropriately matched line that produces safe and effective anti-CMV activity post-HSCT.

Maribavir for Refractory or Resistant Cytomegalovirus Infections in Hematopoietic-cell or Solid-organ Transplant Recipients: A Randomized, Dose-ranging, Double-blind, Phase 2 Study

Background

Cytomegalovirus (CMV) infections that are refractory or resistant (RR) to available antivirals ([val]ganciclovir, foscarnet, cidofovir) are associated with higher mortality in transplant patients. Maribavir is active against RR CMV strains.

Methods

Hematopoietic-cell or solid-organ transplant recipients ≥12 years old with RR CMV infections and plasma CMV deoxyribonucleic acid (DNA) ≥1000 copies/mL were randomized (1:1:1) to twice-daily dose-blinded maribavir 400, 800, or 1200 mg for up to 24 weeks. The primary efficacy endpoint was the proportion of patients with confirmed undetectable plasma CMV DNA within 6 weeks of treatment. Safety analyses included the frequency and severity of treatment-emergent adverse events (TEAEs).

Results

From July 2012 to December 2014, 120 patients were randomized and treated (40 per dose group): 80/120 (67%) patients achieved undetectable CMV DNA within 6 weeks of treatment (95% confidence interval, 57–75%), with rates of 70%, 63%, and 68%, respectively, for maribavir 400, 800, and 1200 mg twice daily. Recurrent on-treatment CMV infections occurred in 25 patients; 13 developed mutations conferring maribavir resistance. Maribavir was discontinued due to adverse events in 41/120 (34%) patients, and 17/41 discontinued due to CMV infections. During the study, 32 (27%) patients died, 4 due to CMV disease. Dysgeusia was the most common TEAE (78/120; 65%) and led to maribavir discontinuation in 1 patient. Absolute neutrophil counts <1000/µL were noted in 12/106 (11%) evaluable patients, with rates similar across doses.

Conclusions

Maribavir ≥400 mg twice daily was active against RR CMV infections in transplant recipients; no new safety signals were identified.

Clinical Trials Registration

NCT01611974.

Evaluation of the Effect of Maribavir on Cardiac Repolarization in Healthy Participants: Thorough QT/QTc Study

Maribavir is an orally bioavailable benzimidazole riboside in clinical development for treatment of cytomegalovirus infection in patients who undergo transplantation. Maribavir was evaluated in a thorough QT (TQT) study to determine any effects on cardiac repolarization. The effect of maribavir 100 and 1,200 mg oral doses on the baseline-adjusted and placebo-adjusted corrected QT (QTc) interval (delta delta QTc (ddQTc)) and other electrocardiogram (ECG) parameters was assessed in a randomized, phase I, placebo-controlled, four-period crossover study in healthy participants (men and women ages 18-50 years). Additionally, maribavir pharmacokinetics, safety, and tolerability were investigated. Moxifloxacin (400 mg) was used as a positive control to demonstrate the study's ability to detect QT prolongation. Digital 12-lead Holter ECG monitoring was performed over 22 hours following study drug administration. Individual, Fridericia's, and Bazett's QTc intervals were calculated. Of 52 randomized participants (29 ± 8.1 years old; 31 men (60%)), 50 (96%) completed the study. For both 100-mg and 1200-mg doses of maribavir, analysis of ddQTc demonstrated that the upper bound of the two-sided 90% confidence interval was below the 10-ms threshold at all time points. The concentration-effect analysis demonstrated no relationship between ddQTc and plasma concentrations of maribavir (and its metabolite). There were no clinically meaningful changes in heart rate and systolic blood pressure. The most common adverse event was dysgeusia; no serious adverse events were reported. This TQT study demonstrated that maribavir did not have impact on cardiac repolarization.

Impact of Preemptive Therapy for Cytomegalovirus on Toxicities after Allogeneic Hematopoietic Cell Transplantation in Clinical Practice: A Retrospective Single-Center Cohort Study

(Val)ganciclovir (vGCV) or foscarnet (FCN) as preemptive therapy (PET) for cytomegalovirus (CMV) after allogeneic hematopoietic cell transplantation (HCT) is associated with myelosuppression and nephrotoxicity, respectively. We analyzed a cohort of CMV-seropositive (R⁺) HCT recipients managed preemptively at a single center. The objectives of our study were to (1) quantify the frequencies of neutropenia and acute kidney injury (AKI) through day +100 (D100) post-HCT and at PET discontinuation and (2) assess the impact of PET on neutropenia and AKI in multivariate models. This was a retrospective cohort study of adult CMV R⁺ recipients who underwent allo-HCT at Memorial Sloan Kettering Cancer Center from March 18, 2013, through December 31, 2017, and were managed with PET. Patients were grouped by receipt of PET (PET and no PET). Neutropenia and AKI were defined by Common Terminology Criteria for Adverse Events version 4. Frequencies of toxicities by D100 were compared between relevant groups. The impact of PET on toxicities was examined in univariate and multivariate Poisson/negative binomial regression models. Of 368 CMV R⁺ HCT recipients, 208 (56.5%) received PET. Neutropenia by D100 occurred in 41.8% and 28.6% patients in PET and no PET, respectively (P = .0009). PET increased the risk of neutropenia (adjusted relative risk = 1.81; 95% confidence interval [CI], 1.48 to 2.21; P < .0001) in multivariate analyses. AKI by D100 occurred in 12.0% and 7.8% patients in PET and no PET, respectively (P = .19). PET increased the risk of AKI by 2.75-fold (95% CI, 1.71 to 4.42; P < .0001). When PET recipients were grouped by first antiviral, neutropenia by D100 occurred in 34.8% and 48.9% of vGCV and FCN recipients, respectively, (P = .08), and AKI occurred in 13.0% and 34.0% of vGCV and FCN recipients, respectively (P = .001). At discontinuation of vGCV or FCN, neutropenia was present in 11.2% versus 2.1% patients, respectively (P = .08), and AKI was present in 1.9% of versus 12.8% patients respectively (P = .005). Preemptive therapy for CMV increased the risk of neutropenia and AKI in the first 100 days post-HCT by 1.8-fold and 2.8-fold, respectively. Our results underscore the need for safer antivirals for CMV management in HCT recipients.

Rapid Regulation of Human Mesenchymal Stem Cell Proliferation Using Inducible Caspase-9 Suicide Gene for Safe Cell-Based Therapy

The regulation of transplanted cell proliferation and function is important to achieve safe cell-based therapies. We previously reported that the proliferation and function of transplanted cells, which expressed the herpes simplex virus thymidine kinase (HSVtk) suicide gene, could be controlled by ganciclovir (GCV) administration. However, there are some concerns regarding the use of GCV. It is reported that the inducible caspase-9 (iC9) gene, a human caspase-9-derived genetically engineered suicide gene, rapidly induces cell apoptosis in the presence of apoptosis inducers, such as AP20187. In this study, we used a combination of the iC9 gene and AP20187 to achieve rapid regulation of transplanted cell proliferation. Cells from the human mesenchymal stem cell line UE7T-13 were transfected with the iC9 gene to obtain UE7T-13/iC9 cells. AP20187 significantly reduced the number of UE7T-13/iC9 cells within 24 h in a concentration-dependent manner. This reduction was much faster than the reduction of HSVtk-expressing UE7T-13 cells induced by GCV addition. Subcutaneous AP20187 administration rapidly reduced the luminescence signal from NanoLuc luciferase (Nluc)-expressing UE7T-13/iC9 cells transplanted into mice. These results indicate that the combined use of the iC9 gene and AP20187 is effective in rapidly regulating transplanted cell proliferation.

Maribavir for Preemptive Treatment of Cytomegalovirus Reactivation

BACKGROUND

Maribavir is a benzimidazole riboside with activity against cytomegalovirus (CMV). The safety and efficacy of maribavir for preemptive treatment of CMV infection in transplant recipients is not known.

METHODS

In a phase 2, open-label, maribavir dose-blinded trial, recipients of hematopoietic-cell or solid-organ transplants (≥18 years of age, with CMV reactivation [1000 to 100,000 DNA copies per milliliter]) were randomly assigned to receive maribavir at a dose of 400, 800, or 1200 mg twice daily or the standard dose of valganciclovir for no more than 12 weeks. The primary efficacy end point was the percentage of patients with a response to treatment, defined as confirmed undetectable CMV DNA in plasma, within 3 weeks and 6 weeks after the start of treatment. The primary safety end point was the incidence of adverse events that occurred or worsened during treatment.

RESULTS

Of the 161 patients who underwent randomization, 159 received treatment, and 156 had postbaseline data available - 117 in the maribavir group and 39 in the valganciclovir group. The percentage of patients with postbaseline data available who had a response to treatment within 3 weeks was 62% among those who received maribavir and 56% among those who received valganciclovir. Within 6 weeks, 79% and 67% of patients, respectively, had a response (risk ratio, 1.20; 95% confidence interval, 0.95 to 1.51). The percentages of patients with a response to treatment were similar among the maribavir dose groups. Two patients who had a response to treatment had a recurrence of CMV infection within 6 weeks after starting maribavir at a dose of 800 mg twice daily; T409M resistance mutations in CMV UL97 protein kinase developed in both patients. The incidence of serious adverse events that occurred or worsened during treatment was higher in the maribavir group than in the valganciclovir group (52 of 119 patients [44%] vs. 13 of 40 [32%]). A greater percentage of patients in the maribavir group discontinued the trial medication because of an adverse event (27 of 119 [23%] vs. 5 of 40 [12%]). A higher incidence of gastrointestinal adverse events was reported with maribavir, and a higher incidence of neutropenia was reported with valganciclovir.

CONCLUSIONS

Maribavir at a dose of at least 400 mg twice daily had efficacy similar to that of valganciclovir for clearing CMV viremia among recipients of hematopoietic-cell or solid-organ transplants. A higher incidence of gastrointestinal adverse events - notably dysgeusia - and a lower incidence of neutropenia were found in the maribavir group. (Funded by ViroPharma/Shire Development; EudraCT number, 2010-024247-32.).

[Modern ethiotropic chemotherapy of human cytomegalovirus infection: clinical effectiveness, molecular mechanism of action, drug resistance, new trends and prospects. Part 1.]

Modern chemotherapy of cytomegalovirus (CMV) infections has a very limited arsenal of first-line drugs. These are preparations of ganciclovir (GCV) belonging to the class of modified nucleosides and its metabolic precursor ganciclovir valine ester. After three-step phosphorylation, GCV, as a structural analogue of the natural nucleotide, competes with it for binding to DNA polymerase and, due to its structural features, inhibits its activity. However, with prolonged use of GCV, mainly under conditions of immunosuppression, the virus develops drug resistance associated in most cases with changes in pUL97 catalyzing the first stage of GCV phosphorylation, as well as in the catalytic subunit of DNA polymerase. When variants of viruses resistant to GCV appear, second-line drugs are used: pyrophosphate analog of foscarnet and nucleotide cidofovir. Resistance to second-line drugs is due to mutations in the pol-gene and in a number of cases leads to multiresistance, which makes it impossible to use traditional anti-CMV drugs. In addition, the use of all of the above drugs is accompanied by the development of severe side effects. All of the above determines the need to search for new compounds that can effectively inhibit the reproduction of the virus, harmless to the macroorganism, convenient to use, overcoming the drug resistance barrier in viruses.As a result of the search in international databases (PubMed, MedLine, eLIBRARY.RU, ClinicalTrials.gov, etc.), the main trends in the search for new anti-CMV agents were identified. In the first part of the review, we concentrated on compounds that are modifications of known antiviral agents currently used in clinical practice, the most promising for the development of drug anti-CMV drugs.

Safety considerations with current and emerging antiviral therapies for cytomegalovirus infection in transplantation

Introduction: Human cytomegalovirus (HCMV) is a major contributor of morbidity and mortality, and its management is essential for the successful outcome of solid organ and hematopoietic stem cell transplantation. Areas covered: This review discusses the safety profiles of currently available and emerging antiviral drugs and the other strategies for HCMV prevention and treatment after transplantation. Expert opinion: Strategies for management of HCMV rely largely on the use of antiviral agents that inhibit viral DNA polymerase (ganciclovir/valganciclovir, foscarnet, and cidofovir/brincidofovir) and viral terminase complex (letermovir), with different types and degrees of adverse effects. An investigational agent, maribavir, exerts its anti-CMV effect through UL97 inhibition, and its safety profile is under clinical evaluation. In choosing the antiviral medication to use, it is important to consider these safety profiles in addition to overall efficacy. In addition to antiviral drugs, reduction of immunosuppression is often generally needed in the management of HCMV infection, but with a potential risk of allograft rejection or graft-versus-host disease. The use of HCMV-specific or non-specific intravenous immunoglobulins remains debated, while adoptive HCMV-specific T cell therapy remains investigational, and associated with unique set of adverse effects.

Mechanisms of AIDS-related cytomegalovirus retinitis

Human cytomegalovirus (HCMV) generates a significant clinical burden worldwide, particularly among the immune compromised. In approximately 30% of untreated HIV/AIDS patients without access or sufficient response to antiretroviral therapies, for example, HCMV causes a sight-threatening retinitis. To study the mechanisms of AIDS-related HCMV retinitis, our lab has for many years used a mouse model in which a mixture of mouse retroviruses induces murine AIDS after approximately 10 weeks, rendering otherwise resistant mice susceptible to opportunistic pathogens. This immunodeficiency combined with subretinal inoculation of murine cytomegalovirus yields a reproducible model of the human disease, facilitating the discovery of many clinically relevant virologic and immunologic mechanisms of retinal destruction which we summarize in this review.

Control of viral infections by epigenetic-targeted therapy

Epigenetics is defined as the science that studies the modifications of gene expression that are not owed to mutations or changes in the genetic sequence. Recently, strong evidences are pinpointing toward a solid interplay between such epigenetic alterations and the outcome of human cytomegalovirus (HCMV) infection. Guided by the previous possibly promising experimental trials of human immunodeficiency virus (HIV) epigenetic reprogramming, the latter is paving the road toward two major approaches to control viral gene expression or latency. Reactivating HCMV from the latent phase ("shock and kill" paradigm) or alternatively repressing the virus lytic and reactivation phases ("block and lock" paradigm) by epigenetic-targeted therapy represent encouraging options to overcome latency and viral shedding or otherwise replication and infectivity, which could lead eventually to control the infection and its complications. Not limited to HIV and HCMV, this concept is similarly studied in the context of hepatitis B and C virus, herpes simplex virus, and Epstein-Barr virus. Therefore, epigenetic manipulations stand as a pioneering research area in modern biology and could constitute a curative methodology by potentially consenting the development of broad-spectrum antivirals to control viral infections in vivo.

The Natural Flavonoid Compound Deguelin Inhibits HCMV Lytic Replication within Fibroblasts

Human cytomegalovirus (HCMV) is a ubiquitous herpesvirus for which there is no vaccine or cure. This viral infection, once acquired, is life-long, residing latently in hematopoietic cells. However, latently infected individuals with weakened immune systems often undergo HCMV reactivation, which can cause serious complications in immunosuppressed and immunocompromised patients. Current anti-viral therapies target late stages of viral replication, and are often met with therapeutic resistance, necessitating the development of novel therapeutics. In this current study, we identified a naturally-occurring flavonoid compound, deguelin, which inhibits HCMV lytic replication. Our findings reveal that nanomolar concentrations of deguelin significantly suppress the production of the infectious virus. Further, we show that deguelin inhibits the lytic cycle during the phase of the replication cycle consistent with early (E) gene and protein expression. Importantly, our data reveal that deguelin inhibits replication of a ganciclovir-resistant strain of HCMV. Together, our findings identify a novel, naturally occurring compound that may prove useful in the treatment of HCMV replication.

Cytomegalovirus resistance in CD34+ -selected hematopoietic cell transplant recipients

BACKGROUND

Cytomegalovirus (CMV) viremia after CD34+ -selected hematopoietic stem cell transplant (HCT) often requires prolonged antiviral therapy. We report rates and outcomes of resistant CMV in a contemporary cohort of CD34+ -selected HCT recipients managed preemptively.

METHODS

We retrospectively reviewed 220 consecutive, CMV-seropositive recipients (R+), who received CD34+ -selected HCT at Memorial Sloan Kettering Cancer Center between June 2010 and December 2014. Patients were monitored by quantitative CMV PCR and were treated preemptively. CMV resistance was tested by a genotypic assay.

RESULTS

One hundred and sixty-one (73%) patients developed CMV viremia and 47 (29% of viremic and 21% of total patients) had CMV resistance testing by one-year from HCT. CMV resistance was confirmed in 19 (12% of viremic and 9% of total) patients and was identified >3 months from HCT in 90% of patients. Twelve patients had mutations in UL97 only; the remaining 7 patients had mutations in UL54 only or UL54 and UL97. By 1 year from HCT, 11 of 19 (58%) patients with mutations had CMV end-organ disease. CMV-related mortality in patients with resistance was 42%.

CONCLUSIONS

Nine percent of CMV R+, CD34+ -selected HCT recipients had resistant CMV by 1 year from HCT. Of 19 patients with resistant CMV, 58% had CMV end-organ disease and 42% died of CMV. Effective strategies for CMV prevention and restoration of CMV immunity are needed for CD34+ -selected HCT.

Characterization and clinical enrichment of HLA-C*07:02-restricted Cytomegalovirus-specific CD8+ T cells

Human Cytomegalovirus (CMV) reactivation remains a major source of morbidity in patients after solid organ and hematopoietic stem cell transplantation (HSCT). Adoptive T cell therapy (ACT) with CMV-specific T cells is a promising therapeutic approach for HSCT recipients, but might be counteracted by CMV’s immune evasion strategies. HLA-C*07:02 is less susceptible to viral immune evasion suggesting HLA-C*07:02-restricted viral epitopes as promising targets for ACT. For a better understanding of HLA-C*07:02-restricted CMV-specific T cells we used recently generated reversible HLA-C*07:02/IE-1 multimers (Streptamers) recognizing a CMV-derived Immediate-Early-1 (IE-1) epitope and analyzed phenotypic and functional T cell characteristics. Initially, we detected very high frequencies of HLA-C*07:02/IE-1 multimer⁺ T cells (median = 11.35%), as well as robust functional responses after stimulation with IE-1 peptide (IFNγ⁺; median = 5.02%) in healthy individuals. However, MHC-multimer⁺ and IFNγ-secreting T cell frequencies showed a relatively weak correlation (r² = 0.77), which could be attributed to an unexpected contribution of CMV-epitope-independent KIR2DL2/3-binding of HLA-C*07:02/IE-1 multimers. Therefore, we developed a MHC-multimer double-staining approach against a cancer epitope-specific HLA-C*07:02 multimer to identify truly HLA-C*07:02/IE-1 epitope-specific T cells. The frequencies of these truly HLA-C*07:02/IE-1 multimer⁺ T cells were still high (median = 6.86%) and correlated now strongly (r² = 0.96) with IFNγ-secretion. Interestingly, HLA-C*07:02/IE-1-restricted T cells contain substantial numbers with a central memory T cell phenotype, indicating high expansion potential e.g. for ACT. In line with that, we developed a clinical enrichment protocol avoiding epitope-independent KIR-binding to make HLA-C*07:02/IE-1-restricted T cells available for ACT. Initial depletion of KIR-expressing CD8⁺ T cells followed by HLA-C*07:02/IE-1 Streptamer positive selection using paramagnetic labeling techniques allowed to enrich successfully HLA-C*07:02/IE-1-restricted T cells. Such specifically enriched populations of functional HLA-C*07:02/IE-1-restricted T cells with significant central memory T cell content could become a potent source for ACT.

Pharmacokinetics and Safety of Letermovir Coadministered With Cyclosporine A or Tacrolimus in Healthy Subjects

Letermovir is being developed for human cytomegalovirus infection treatment and prophylaxis. In patients receiving transplants, antivirals are coadministered with cyclosporine A (CsA) or tacrolimus (TAC) immunosuppressants. Therefore, we investigated the potential for letermovir-immunosuppressant interactions. In 2 phase 1 clinical trials either CsA 50 mg or TAC 5 mg was administered to healthy males. Following washout, letermovir 80 mg was dosed twice daily for 7 and 11 days in the CsA and TAC trials, respectively, with a second dose of immunosuppressant coadministered with letermovir at steady state. In addition, letermovir 40 mg twice daily was administered for 14 days, and either CsA 50 or 200 mg administered on days 7 and 14. Pharmacokinetics and tolerability were assessed. Letermovir increased CsA and TAC C_max by 37% and 70%, respectively, and exposure by 70% and 78%, respectively, compared with immunosuppressant alone; t_½ was also increased from 10.7 to 17.9 hours for CsA. CsA (50/200 mg) increased letermovir C_max,ss (109%/167%) and AUC_ss,τ (126%/237%) and decreased t_½ (4.33 to 3.68/3.04 hours) versus letermovir alone. TAC did not significantly affect letermovir pharmacokinetics. All treatments were well tolerated. Concomitant letermovir increased TAC and CsA exposure. CsA altered letermovir pharmacokinetics, whereas TAC did not.

Pharmacokinetics and safety of the anti-human cytomegalovirus drug letermovir in subjects with hepatic impairment

AIMS

Human cytomegalovirus constitutes a prevalent and serious threat to immunocompromised individuals and requires new treatments. Letermovir is a novel viral-terminase inhibitor that has demonstrated prophylactic/pre-emptive activity against human cytomegalovirus in Phase 2 and 3 transplant trials. As unchanged letermovir is primarily excreted via the liver by bile, this trial aimed to assess the effect of hepatic impairment on letermovir pharmacokinetics.

METHODS

Phase 1, open-label, parallel-group pharmacokinetic and safety comparison of multiple once-daily oral letermovir in female subjects with hepatic impairment and healthy matched controls. For 8 days, subjects with moderate hepatic impairment (n = 8) and their matched healthy controls (n = 9) received 60 mg letermovir/day and those with severe hepatic impairment (n = 8) and their matched healthy controls (n = 8) received 30 mg letermovir/day. Pharmacokinetic parameters were determined from blood samples.

RESULTS

For subjects with moderate hepatic impairment, maximal observed concentration at steady state (C_ss,max ) and the area under the concentration vs. time curve over a dosing interval at steady state (AUC_τ,ss ) for total letermovir were 1.37-fold (90% confidence interval: 0.87, 2.17) and 1.59-fold (0.98, 2.57) higher, respectively, than in healthy subjects. For subjects with severe hepatic impairment, C_ss,max and AUC_τ,ss values of total letermovir were 2.34-fold (1.91, 2.88) and 3.82-fold (2.94, 4.97) higher, respectively, compared with healthy subjects.

CONCLUSIONS

Moderate hepatic impairment increased exposure to letermovir <2-fold, while severe hepatic impairment increased letermovir exposure approximately 4-fold as compared with healthy subjects. Letermovir 60/30 mg/day was generally well-tolerated in subjects with hepatic impairment.

Pharmacokinetics and safety of letermovir, a novel anti-human cytomegalovirus drug, in patients with renal impairment

AIMS

Human cytomegalovirus remains a significant issue for immunocompromised patients and existing viral polymerase targeting therapies are associated with significant toxicity. Accordingly, the viral terminase complex inhibitor, letermovir, is in development. We assessed letermovir pharmacokinetics in renal impairment.

METHODS

This was a Phase 1, open-label, nonrandomised trial. Estimated glomerular filtration rate based on the Modification of Diet Renal Disease equation was used to create three groups of eight subjects: healthy function (estimated glomerular filtration rate ≥ 90 ml min^-1  1.73m^-2 ), moderate (30-59 ml min^-1  1.73m^-2 ) and severe (<30 ml min^-1  1.73m^-2 ) impairment. Oral letermovir 120 mg was dosed once-daily for 8 days and blood collected for pharmacokinetic analyses.

RESULTS

All 24 subjects enrolled completed the trial. Moderate and severe renal impairment increased mean unbound letermovir fractions by 11% and 26%, respectively, vs. healthy subjects. Exposure (AUC_τ,ss and C_ss,max ) was increased with renal impairment [least square mean ratios (90% confidence intervals) total letermovir vs. healthy subjects, AUC_τ,ss 192% (143-258%) and 142% (83-243%) for moderate and severe impairment, respectively; C_ss,max 125% (87-182%) and 106% (75-151%), respectively]. Clearance was decreased vs. healthy subjects. Correlation analyses indicated a correlation between decreasing renal function and increased unbound letermovir concentration (R²  = 0.5076, P < 0.0001). Correlations were identified between decreased clearance with both decreased renal function (R²  = 0.0662, P = 0.2249 and R²  = 0.1861, P = 0.0353 total and unbound clearance, respectively) and increased age (R²  = 0.3548, P = 0.0021 and R²  = 0.3166, P = 0.0042 total and unbound clearance, respectively). Multiple-dose letermovir 120 mg was well tolerated across groups.

CONCLUSIONS

Renal impairment increased exposure to letermovir, although age was a confounding factor.

Kinome Profiling Identifies Druggable Targets for Novel Human Cytomegalovirus (HCMV) Antivirals

Human cytomegalovirus (HCMV) is a significant cause of disease in immune-compromised adults and immune naïve newborns. No vaccine exists to prevent HCMV infection, and current antiviral therapies have toxic side effects that limit the duration and intensity of their use. There is thus an urgent need for new strategies to treat HCMV infection. Repurposing existing drugs as antivirals is an attractive approach to limit the time and cost of new antiviral drug development. Virus-induced changes in infected cells are often driven by changes in cellular kinase activity, which led us to hypothesize that defining the complement of kinases (the kinome), whose abundance or expression is altered during infection would identify existing kinase inhibitors that could be repurposed as new antivirals. To this end, we applied a kinase capture technique, multiplexed kinase inhibitor bead-mass spectrometry (MIB-MS) kinome, to quantitatively measure perturbations in >240 cellular kinases simultaneously in cells infected with a laboratory-adapted (AD169) or clinical (TB40E) HCMV strain. MIB-MS profiling identified time-dependent increases and decreases in MIB binding of multiple kinases including cell cycle kinases, receptor tyrosine kinases, and mitotic kinases. Based on the kinome data, we tested the antiviral effects of kinase inhibitors and other compounds, several of which are in clinical use or development. Using a novel flow cytometry-based assay and a fluorescent reporter virus we identified three compounds that inhibited HCMV replication with IC50 values of <1 μm, and at doses that were not toxic to uninfected cells. The most potent inhibitor of HCMV replication was OTSSP167 (IC50 <1.2 nm), a MELK inhibitor, blocked HCMV early gene expression and viral DNA accumulation, resulting in a >3 log decrease in virus replication. These results show the utility of MIB-MS kinome profiling for identifying existing kinase inhibitors that can potentially be repurposed as novel antiviral drugs.

Single Chain Antibodies Against gp55 of Human Cytomegalovirus (HCMV) for Prophylaxis and Treatment of HCMV Infections

Background:

Immunotherapy is a promising prospective new treatment for cytomegalovirus (CMV) infections. Neutralizing effects have been reported using monoclonal antibodies. Recombinant single chain antibodies (scFvs) due to their advantages over monoclonal antibodies are potential alternatives and provide valuable clinical agents.

Objectives:

The aim of this study was to select specific single chain antibodies against gp55 of CMV and to evaluate their neutralizing effects. In the present study, we selected specific single chain antibodies against glycoprotein 55 (gp55) of CMV for their use in treatment and diagnosis.

Materials and Methods:

Single chain antibodies specific against an epitope located in the C-terminal part of gp55 were selected from a phage antibody display library. After four rounds of panning, twenty clones were amplified by the polymerase chain reaction (PCR) and fingerprinted by MvaI restriction enzyme. The reactivities of the specific clones were tested by the enzyme-linked immunosorbent assay (ELISA) and the neutralizing effects were evaluated by the plaque reduction assay.

Results:

Fingerprinting of selected clones revealed three specific single chain antibodies (scFv1, scFv2 and scFv3) with frequencies 25%, 20 and 20%. The clones produced positive ELISA with the corresponding peptide. The percentages of plaque reduction for scFv1, scFv2 and scFv3 were 23.7, 68.8 and 11.6, respectively.

Conclusions:

Gp55 of human CMV is considered as an important candidate for immunotherapy. In this study, we selected three specific clones against gp55. The scFvs reacted only with the corresponding peptide in a positive ELISA. The scFv2 with 68.8% neutralizing effect showed the potential to be considered for prophylaxis and treatment of CMV infections, especially in solid organ transplant recipients, for whom treatment of CMV is urgently needed. The scFv2 with neutralizing effect of 68.8%, has the potential to be considered for treatment of these patients. The specific scFv1 and scFv3 with lower neutralizing effects can be used for diagnostic purposes.

Anemia in children following renal transplantation-results from the ESPN/ERA-EDTA Registry

BACKGROUND

Our aim was to determine the prevalence of sub-target hemoglobin (Hb) levels in children with a renal allograft and to identify potential determinants associated with these Hb levels.

METHODS

Data from 3669 children with a functioning renal allograft, aged <18 years between 1 January 2000 and 31 December 2012, from 20 European countries were retrieved from the ESPN/ERA-EDTA Registry, providing 16,170 Hb measurements.

RESULTS

According to the NKF/KDOQI classification and the UK-NICE guidelines, 49.8 and 7.8% of the patients, respectively, were anemic. Hb levels were strongly associated with graft function, with Hb levels of 12.6 g/dl in children with chronic kidney disease (CKD) stage 1, declining to 10.7 g/dl in children with CKD stage 5 (P < 0.001). Higher Hb levels were associated with the use of tacrolimus compared to ciclosporin (0.14 g/dl; 95% confidence interval 0.02-0.27; P = 0.002). Low Hb levels were associated with an increased risk of graft failure (P = 0.01) or combined graft failure and death (P < 0.01), but not with death alone (not significant).

CONCLUSIONS

Anemia is present in a significant proportion of European pediatric kidney transplant recipients and is associated with renal allograft dysfunction and type of immunosuppressants used. In our patient cohort, higher Hb levels were associated with better graft and patient survival and less hypertension.

Treatment of Cytomegalovirus Infection with Cidofovir and CMV Immune Globulin in a Lung Transplant Recipient

Cytomegalovirus (CMV) infection after lung transplantation is associated with increased risk for pneumonitis and bronchiolitis obliterans as well as allograft rejection and opportunistic infections. Ganciclovir is the mainstay of prophylaxis and treatment but CMV infections can be unresponsive. Apart from direct antiviral drugs, CMV immunoglobulin (CMVIG) preparations may be considered but are only licensed for prophylaxis. A CMV-seronegative 42-year-old man with cystic fibrosis received a lung from a CMV-seropositive donor. Intravenous ganciclovir prophylaxis was delayed until day 12 due to acute postoperative renal failure and was accompanied by five doses of CMVIG (10 g). By day 16, CMV-DNA was detectable and rising; CMV-specific T-cells were undetectable. Switch from ganciclovir to foscarnet prompted a transient decrease in CMV viral load, but after increasing again to reach 3600 copies/mL foscarnet was changed to intravenous cidofovir and CMVIG was restarted. CMV load continued to fluctuate and declined slowly, whereas CMV-specific T-cells were detected five months later and increased thereafter. At last follow-up, the patient was in very good clinical condition with no evidence of bronchiolitis obliterans. No side effects of this treatment were observed. In this hard-to-treat case, the combination of cidofovir with off-label use of CMVIG contributed to a successful outcome.

The Impact of Infection on Chronic Allograft Dysfunction and Allograft Survival After Solid Organ Transplantation

Infectious diseases after solid organ transplantation (SOT) are a significant cause of morbidity and reduced allograft and patient survival; however, the influence of infection on the development of chronic allograft dysfunction has not been completely delineated. Some viral infections appear to affect allograft function by both inducing direct tissue damage and immunologically related injury, including acute rejection. In particular, this has been observed for cytomegalovirus (CMV) infection in all SOT recipients and for BK virus infection in kidney transplant recipients, for community-acquired respiratory viruses in lung transplant recipients, and for hepatitis C virus in liver transplant recipients. The impact of bacterial and fungal infections is less clear, but bacterial urinary tract infections and respiratory tract colonization by Pseudomonas aeruginosa and Aspergillus spp appear to be correlated with higher rates of chronic allograft dysfunction in kidney and lung transplant recipients, respectively. Evidence supports the beneficial effects of the use of antiviral prophylaxis for CMV in improving allograft function and survival in SOT recipients. Nevertheless, there is still a need for prospective interventional trials assessing the potential effects of preventive and therapeutic strategies against bacterial and fungal infection for reducing or delaying the development of chronic allograft dysfunction.