Ibrexafungerp is efficacious in a neutropenic murine model of pulmonary mucormycosis as monotherapy and combined with liposomal amphotericin B.

Ibrexafungerp (formerly SCY-078) is the first member of the triterpenoid class that prevents the synthesis of the fungal cell wall polymer ß-(1,3)-D-glucan by inhibiting the enzyme glucan synthase. We evaluated the in vivo efficacy of ibrexafungerp against pulmonary mucormycosis using an established murine model. Neutropenic mice were intratracheally infected with either Rhizopus delemar or Mucor circinelloides. Treatment with placebo (diluent control), ibrexafungerp (30 mg/kg, PO BID), liposomal amphotericin B (LAMB 10 mg/kg IV QD), posaconazole (PSC 30 mg/kg PO QD), or a combination of ibrexafungerp plus LAMB or ibrexafungerp plus PSC began 16 h post-infection and continued for 7 days for ibrexafungerp or PSC and through day 4 for LAMB. Ibrexafungerp was as effective as LAMB or PSC in prolonging median survival (range: 15 days to >21 days) and enhancing overall survival (30%-65%) vs placebo (9 days and 0%; P < 0.001) in mice infected with R. delemar. Furthermore, median survival and overall percent survival resulting from the combination of ibrexafungerp plus LAMB were significantly greater compared to all monotherapies (P ≤ 0.03). Similar survival results were observed in mice infected with M. circinelloides. Monotherapies also reduce the lung and brain fungal burden by ~0.5-1.0log10 conidial equivalents (CE)/g of tissue vs placebo in mice infected with R. delemar (P < 0.05), while a combination of ibrexafungerp plus LAMB lowered the fungal burden by ~0.5-1.5log10 CE/g compared to placebo or any of the monotherapy groups (P < 0.03). These results are promising and warrant continued investigation of ibrexafungerp as a novel treatment option against mucormycosis.

Ibrexafungerp Versus Placebo for Vulvovaginal Candidiasis Treatment: A Phase 3, Randomized, Controlled Superiority Trial (VANISH 303).

BACKGROUND: Current treatment of vulvovaginal candidiasis (VVC) is largely limited to azole therapy. Ibrexafungerp is a first-in-class triterpenoid antifungal with broad-spectrum anti-Candida fungicidal activity. The objective of this study was to evaluate the efficacy and safety of ibrexafungerp compared with placebo in patients with acute VVC. METHODS: Patients were randomly assigned 2:1 to receive ibrexafungerp (300 mg twice for 1 day) or placebo. The primary endpoint was the percentage of patients with a clinical cure (complete resolution of vulvovaginal signs and symptoms [VSS] = 0) at test-of-cure (day 11 ± 3). Secondary endpoints included the percentage of patients with mycological eradication, overall success (clinical cure and mycological eradication), clinical improvement (VSS ≤ 1) at test-of-cure, and symptom resolution at follow-up (day 25 ± 4). RESULTS: Patients receiving ibrexafungerp had significantly higher rates of clinical cure (50.5% [95/188] vs 28.6% [28/98]; P = .001), mycological eradication (49.5% [93/188] vs 19.4% [19/98]; P < .001), and overall success (36.0% [64/178] vs 12.6% [12/95]; P < .001) compared with placebo. Symptom resolution was sustained and further increased with ibrexafungerp compared with placebo (59.6% [112/188] vs 44.9% [44/98]; P = .009) at follow-up. Post hoc analysis showed similar rates of clinical cure and clinical improvement at test-of-cure for Black patients (54.8% [40/73] and 63.4% [47/73], respectively) and patients with a body mass index >35 (54.5% [24/44] and 68.2% [30/44], respectively) compared with overall rates. Ibrexafungerp was well tolerated. Adverse events were primarily gastrointestinal and mild in severity. CONCLUSIONS: Ibrexafungerp provides a promising safe and efficacious oral treatment that mechanistically differs from current azole treatment options for acute VVC.

In Vitro pH Activity of Ibrexafungerp against Fluconazole-Susceptible and -Resistant Candida Isolates from Women with Vulvovaginal Candidiasis.

The vaginal environment with candidiasis has a pH of 3.8 to 4.5 and this has a negative effect on the activity of antifungals. Ibrexafungerp was evaluated against 187 Candida isolates, including fluconazole-sensitive and -resistant Candida albicans, Candida glabrata, Candida krusei, Candida parapsilosis, and Candida tropicalis with the media adjusted to pH 7.0 and pH 4.5. Ibrexafungerp MIC values were not adversely affected when tested at pH 4.5. Ibrexafungerp exhibited significant activity against all isolates at pH 4.5.

A Second-Generation Fungerp Analog, SCY-247, Shows Potent In Vivo Activity in a Murine Model of Hematogenously Disseminated Candida albicans.

Echinocandins are a first-line therapy for Candida infections through their ability to inhibit the synthesis of polymer ß-(1,3)-d-glucan. However, there has been an emergence of multidrug-resistant fungal species necessitating the development of novel antifungal agents to combat invasive fungal infections. SCY-247, a second-generation glucan synthase inhibitor of the triterpenoid class (fungerps), is currently being developed as a potential therapy option. We determined the pharmacokinetics (PKs) of SCY-247 following oral (gavage) administration in mice and evaluated the efficacy of SCY-247 in a murine model of hematogenously disseminated candidiasis caused by Candida albicans Plasma concentrations of SCY-247 were measurable through the last collected time point in all dose groups. Mean concentrations of SCY-247 increased with dose levels, with concentrations of SCY-247 higher after multiple doses than after a single dose. Treatment with SCY-247 resulted in decreased fungal burden and improvement in survival rates against C. albicans disseminated infection. Treatment with 10 mg/kg of body weight of SCY-247 showed a significant reduction in CFU compared with the untreated control (3-log decrease on average) (P = 0.008). Similarly, 40 mg/kg SCY-247 demonstrated a statistically significant reduction in kidney CFU compared with untreated mice (average log CFU ± SD of 2.38 ± 2.58 versus 6.26 ± 0.51; P = 0.001). Mice treated with SCY-247 at 40 mg/kg exhibited a 100% survival rate at the end of the study, contrasted with 62.5% (5 of 8) survival rate in untreated mice. The results of this investigation indicate that SCY-247 is a promising novel anti-fungal agent with activity against Candida infections.

Efficacy of Antistaphylococcal Lysin LSVT-1701 in Combination with Daptomycin in Experimental Left-Sided Infective Endocarditis Due to Methicillin-Resistant Staphylococcus aureus.

We utilized the rabbit model of aortic valve infective endocarditis to examine the combined efficacy of the lysin LSVT-1701 plus daptomycin. The combination of LSVT-1701 plus daptomycin was highly effective at reducing methicillin-resistant Staphylococcus aureus (MRSA) counts in target tissue. When given for four daily doses, both lysin dose regimens in combination with daptomycin sterilized all target tissues. These findings suggest that LSVT-1701 warrants further clinical evaluation as an adjunctive therapy for the treatment of invasive MRSA infections.

A Second-Generation Fungerp Analog, SCY-247, Shows Potent In Vitro Activity against Candida auris and Other Clinically Relevant Fungal Isolates.

Due to the increase of antifungal drug resistance and difficulties associated with drug administration, new antifungal agents for invasive fungal infections are needed. SCY-247 is a second-generation fungerp antifungal compound that interferes with the synthesis of the fungal cell wall polymer ß-(1,3)-d-glucan. We conducted an extensive antifungal screen of SCY-247 against yeast and mold strains compared with the parent compound ibrexafungerp (IBX; formerly SCY-078) to evaluate the in vitro antifungal properties of SCY-247. SCY-247 demonstrated similar activity to IBX against all of the organisms tested. Moreover, SCY-247 showed a higher percentage of fungicidal activity against the panel of yeast and mold isolates than IBX. Notably, SCY-247 showed considerable antifungal properties against numerous strains of Candida auris Additionally, SCY-247 retained its antifungal activity when evaluated in the presence of synthetic urine, indicating that SCY-247 maintains activity and structural stability under environments with decreased pH levels. Finally, a time-kill study showed SCY-247 has potent anti-Candida, -Aspergillus, and -Scedosporium activity. In summary, SCY-247 has potent antifungal activity against various fungal species, indicating that further studies on this fungerp analog are warranted.

Combination Therapy with Ibrexafungerp (Formerly SCY-078), a First-in-Class Triterpenoid Inhibitor of (1→3)-ß-d-Glucan Synthesis, and Isavuconazole for Treatment of Experimental Invasive Pulmonary Aspergillosis.

Ibrexafungerp (formerly SCY-078) is a semisynthetic triterpenoid and potent (1→3)-ß-d-glucan synthase inhibitor. We investigated the in vitro activity, pharmacokinetics, and in vivo efficacy of ibrexafungerp (SCY) alone and in combination with antimold triazole isavuconazole (ISA) against invasive pulmonary aspergillosis (IPA). The combination of ibrexafungerp and isavuconazole in in vitro studies resulted in additive and synergistic interactions against Aspergillus spp. Plasma concentration-time curves of ibrexafungerp were compatible with linear dose proportional profile. In vivo efficacy was studied in a well-established persistently neutropenic New Zealand White (NZW) rabbit model of experimental IPA. Treatment groups included untreated control (UC) rabbits and rabbits receiving ibrexafungerp at 2.5 (SCY2.5) and 7.5 (SCY7.5) mg/kg of body weight/day, isavuconazole at 40 (ISA40) mg/kg/day, or combinations of SCY2.5+ISA40 and SCY7.5+ISA40. The combination of SCY+ISA produced an in vitro synergistic interaction. There were significant in vivo reductions of residual fungal burden, lung weights, and pulmonary infarct scores in SCY2.5+ISA40, SCY7.5+ISA40, and ISA40 treatment groups versus those of the SCY2.5-treated, SCY7.5-treated, and UC (P < 0.01) groups. Rabbits treated with SCY2.5+ISA40 and SCY7.5+ISA40 had prolonged survival in comparison to that of the SCY2.5-, SCY7.5-, ISA40-treated, or UC (P < 0.05) groups. Serum galactomannan index (GMI) and (1→3)-ß-d-glucan levels significantly declined in animals treated with the combination of SCY7.5+ISA40 in comparison to those of animals treated with SCY7.5 or ISA40 (P < 0.05). Ibrexafungerp and isavuconazole combination demonstrated prolonged survival, decreased pulmonary injury, reduced residual fungal burden, and lower GMI and (1→3)-ß-d-glucan levels in comparison to those of single therapy for treatment of IPA. These findings provide an experimental foundation for clinical evaluation of the combination of ibrexafungerp and an antimold triazole for treatment of IPA.

SCY-078, a Novel Fungicidal Agent, Demonstrates Distribution to Tissues Associated with Fungal Infections during Mass Balance Studies with Intravenous and Oral [14C]SCY-078 in Albino and Pigmented Rats.

SCY-078, a fungicidal ß-1,3-glucan synthesis inhibitor administered as intravenous or oral [14C]SCY-078 to rats, was distributed primarily into tissues associated with invasive fungal disease (kidney, lung, liver, spleen, bone marrow, muscle, vaginal tissue, and skin) to levels exceeding those in plasma. Oral fraction absorbed was ∼40%. Elimination was primarily via bile and feces (∼90%) and urine (∼1.5%). Mean half-time was ∼8 h. Quantitative whole-body autoradiography showed a rapid distribution at 8 h and elimination by 168 h postdose.

SCY-078 Is Fungicidal against Candida Species in Time-Kill Studies.

SCY-078 is an orally bioavailable ß-1,3-glucan synthesis inhibitor (GSI) and the first-in-class of structurally novel triterpene antifungals in clinical development for treating candidemia and invasive candidiasis. In vitro susceptibilities by broth microdilution, antifungal carryover, and time-kill dynamics were determined for three reference (ATCC) strains (Candida albicans 90028, Candida parapsilosis 90018, and Candida tropicalis 750), a quality-control (QC) strain (Candida krusei 6258), and four other strains (C. albicans MYA-2732, 64124, and 76485 and Candida glabrata 90030). Caspofungin (CASP), fluconazole (FLC), and voriconazole (VRC) were comparators. For time-kill experiments, SCY-078 and CASP were evaluated at 0.25, 1, 2, 4, 8, and 16 times the MIC80, and FLU and VRC were evaluated at 4× MIC80 The time to reach 50%, 90%, and 99.9% reduction in the number of CFUs from the starting inoculum was determined. Net change in the number of CFU per milliliter was used to determine 50% and 90% effective concentrations and maximum effect (EC50, EC90, and Emax, respectively). The SCY-078 MIC range was between 0.0625 and 1 µg/ml and generally similar to that of CASP. Antifungal carryover was not observed for SCY-078. SCY-078 was fungicidal against seven isolates at ≥4× MIC (kill of ≥3 log10) and achieved a 1.7-log10 reduction in CFU count/milliliter against C. albicans 90028. CASP behaved similarly against each isolate and achieved a 1.5-log10 reduction in the number of CFU/milliliter against C. albicans 90028. Reductions of 50% in CFU count/milliliter were achieved rapidly (1 to 2.8 h); fungicidal endpoints were reached at 12.1 to 21.8 h at ≥4× MIC. EC90 was reached at ∼5× MIC at each time point to 24 h. The EC50 and EC90 values were generally similar (8 to 24 h). Time-kill behavior of CASP was similar to that of SCY-078. FLC and VRC were fungistatic. Overall, SCY-078 has primarily fungicidal activity against Candida spp. and behaved comparably to CASP.

Differential Activity of the Oral Glucan Synthase Inhibitor SCY-078 against Wild-Type and Echinocandin-Resistant Strains of Candida Species.

SCY-078 (formerly MK-3118) is a novel orally active inhibitor of fungal ß-(1,3)-glucan synthase (GS). SCY-078 is a derivative of enfumafungin and is structurally distinct from the echinocandin class of antifungal agents. We evaluated the in vitro activity of this compound against wild-type (WT) and echinocandin-resistant isolates containing mutations in the FKS genes of Candida spp. Against 36 Candida spp. FKS mutants tested, 30 (83.3%) were non-WT to 1 or more echinocandins, and only 9 (25.0%) were non-WT (MIC, >WT-upper limit) to SCY-078. Among C. glabrata isolates carrying FKS alterations, 84.0% were non-WT to the echinocandins versus only 24.0% for SCY-078. In contrast to the echinocandin comparators, the activity of SCY-078 was minimally affected by the presence of FKS mutations, suggesting that this agent is useful in the treatment of Candida infections due to echinocandin-resistant strains.

De Novo Acquisition of Resistance to SCY-078 in Candida glabrata Involves FKS Mutations That both Overlap and Are Distinct from Those Conferring Echinocandin Resistance.

SCY-078 is an orally active antifungal whose target is the ß-(1,3)-d-glucan synthase (GS). We evaluated the spontaneous emergence of SCY-078-resistant Candida glabrata isolates following drug exposure in vitro Resistant isolates were analyzed using broth microdilution methodology and FKS sequencing. The kinetic inhibition parameter IC50 (50% inhibitory concentration) was also determined from GS complexes. The spectrum of resistance mutations found suggested a partially overlapping but independent binding site for SCY-078 relative to echinocandins on GS.

Antifungal Activity of SCY-078 and Standard Antifungal Agents against 178 Clinical Isolates of Resistant and Susceptible Candida Species.

SCY-078 in vitro activity was determined for 178 isolates of resistant or susceptible Candida albicans, Candida dubliniensis, Candida glabrata, Candida krusei, Candida lusitaniae, and Candida parapsilosis, including 44 Candida isolates with known genotypic (FKS1 or FKS2 mutations), phenotypic, or clinical resistance to echinocandins. Results were compared to those for anidulafungin, caspofungin, micafungin, fluconazole, and voriconazole. SCY-078 was shown to have excellent activity against both wild-type isolates and echinocandin- and azole-resistant isolates of Candida species.

Preclinical Pharmacokinetics and Pharmacodynamic Target of SCY-078, a First-in-Class Orally Active Antifungal Glucan Synthesis Inhibitor, in Murine Models of Disseminated Candidiasis.

SCY-078 (MK-3118) is a novel, semisynthetic derivative of enfumafungin and represents the first compound of the triterpene class of antifungals. SCY-078 exhibits potent inhibition of ß-(1,3)-d-glucan synthesis, an essential cell wall component of many pathogenic fungi, including Candida spp. and Aspergillus spp. SCY-078 is currently in phase 2 clinical development for the treatment of invasive fungal diseases. In vitro disposition studies to assess solubility, intestinal permeability, and metabolic stability were predictive of good oral bioavailability. Preclinical pharmacokinetic studies were consistent with once-daily administration to humans. After intravenous delivery, plasma clearance in rodents and dogs was low, representing <15% and <25% of hepatic blood flow, respectively. The terminal elimination-phase half-life was 5.5 to 8.7 h in rodents, and it was ∼9.3 h in dogs. The volume of distribution at steady-state was high (4.7 to 5.3 liters/kg), a finding suggestive of extensive tissue distribution. Exposure of SCY-078 in kidney tissue, a target organ for invasive fungal disease such as candidiasis, exceeded plasma by 20- to 25-fold for the area under the concentration-time curve from 0 h to infinity (AUC0-∞) and Cmax SCY-078 achieved efficacy endpoints following oral delivery across multiple murine models of disseminated candidiasis. The pharmacokinetic/pharmacodynamic indices Cmax/MIC and AUC/MIC correlated with outcome. Target therapeutic exposure, expressed as the plasma AUC0-24, was comparable across models, with an upper value of 11.2 µg·h/ml (15.4 µM·h); the corresponding mean value for free drug AUC/MIC was ∼0.75. Overall, these results demonstrate that SCY-078 has the oral and intravenous (i.v.) pharmacokinetic properties and potency in murine infection models of disseminated candidiasis to support further investigation as a novel i.v. and oral treatment for invasive fungal diseases.

The Emerging Pathogen Candida auris: Growth Phenotype, Virulence Factors, Activity of Antifungals, and Effect of SCY-078, a Novel Glucan Synthesis Inhibitor, on Growth Morphology and Biofilm Formation.

Candidaauris, a new multidrug-resistant Candida spp. which is associated with invasive infection and high rates of mortality, has recently emerged. Here, we determined the virulence factors (germination, adherence, biofilm formation, phospholipase and proteinase production) of 16 C. auris isolates and their susceptibilities to 11 drugs belonging to different antifungal classes, including a novel orally bioavailable 1,3-ß-d-glucan synthesis inhibitor (SCY-078). We also examined the effect of SCY-078 on the growth, ultrastructure, and biofilm-forming abilities of C. auris Our data showed that while the tested strains did not germinate, they did produce phospholipase and proteinase in a strain-dependent manner and had a significantly reduced ability to adhere and form biofilms compared to that of Candida albicans (P = 0.01). C. auris isolates demonstrated reduced susceptibility to fluconazole and amphotericin B, while, in general, they were susceptible to the remaining drugs tested. SCY-078 had an MIC90 of 1 mg/liter against C. auris and caused complete inhibition of the growth of C. auris and C. albicans Scanning electron microscopy analysis showed that SCY-078 interrupted C. auris cell division, with the organism forming abnormal fused fungal cells. Additionally, SCY-078 possessed potent antibiofilm activity, wherein treated biofilms demonstrated significantly reduced metabolic activity and a significantly reduced thickness compared to the untreated control (P < 0.05 for both comparisons). Our study shows that C. auris expresses several virulence determinants (albeit to a lesser extent than C. albicans) and is resistant to fluconazole and amphotericin B. SCY-078, the new orally bioavailable antifungal, had potent antifungal/antibiofilm activity against C. auris, indicating that further evaluation of this antifungal is warranted.

Cyclophilin inhibitors reduce phosphorylation of RNA-dependent protein kinase to restore expression of IFN-stimulated genes in HCV-infected cells.

BACKGROUND & AIMS: Cyclophilin inhibitors are being developed for treatment of hepatitis C virus (HCV) infection. They are believed to inhibit the HCV replication complex. We investigated whether cyclophilin inhibitors interact with interferon (IFN) signaling in cultured cells infected with HCV. METHODS: We used immunoblot assays to compare expression of IFN-stimulated genes (ISGs) and of components of IFN signaling in HCV-infected and uninfected cells. RESULTS: Incubation with IFN alfa induced expression of ISGs in noninfected cells and, to a lesser extent, in HCV-infected cells; addition of the cyclophilin inhibitor SCY-635 restored expression of ISG products in HCV-infected cells. SCY-635 reduced phosphorylation of double-strand RNA-dependent protein kinase (PKR) and its downstream factor eIF2α; the phosphorylated forms of these proteins are negative regulators of ISG translation. Cyclophilin A interacted physically with PKR; this interaction was disrupted by SCY-635. SCY-635 also suppressed PKR-mediated formation of stress granules. Cyclophilin inhibitors were found to inhibit PKR phosphorylation and stress granule formation in HCV-infected and uninfected cells. CONCLUSIONS: In cultured cells, cyclophilin inhibitors reverse the attenuation of the IFN response by HCV, in addition to their effects on HCV replication complex. Cyclophilin A regulation of PKR has been proposed as a mechanism for observed effects of cyclophilin inhibitors on IFN signaling. We found that cyclophilin inhibitors reduce phosphorylation of PKR and eIF2α during HCV infection to allow for translation of ISG products. Proteins in this pathway might be developed as targets for treatment of HCV infection.

No detectable resistance to tenofovir disoproxil fumarate after 6 years of therapy in patients with chronic hepatitis B.

UNLABELLED: One major challenge in the treatment of chronic hepatitis B is to maintain long-term viral suppression without promoting the selection of drug-resistant mutations. We analyzed data from 347 hepatitis B e antigen-negative and 238 hepatitis B e antigen positive patients receiving tenofovir disoproxil fumarate (TDF) in an open-label, longterm extension of two phase 3 studies. To date, resistance analyses have been completed for patients receiving up to 288 weeks (6 years) of TDF. Population sequencing of hepatitis B virus (HBV) polymerase/reverse transcriptase (pol/RT) was attempted for all patients at baseline, and any patient who remained viremic (HBV DNA 400 copies/mL [69 IU/mL]) at week 288 or at the end of treatment with TDF (n552) or emtricitabine(FTC)/TDF (n57). Phenotypic analyses were performed in HepG2 cells using recombinant HBV containing patient pol/RT sequences. Approximately half of the patients on open-label treatment who qualified for genotyping had pol/RT sequence changes compared to baseline (23/52 [44%] on TDF, 4/7 [57%] on FTC/TDF). Most changes were at polymorphic sites and none were associated with TDF resistance. Virologic breakthrough occurred infrequently and was associated with nonadherence to study medication in the majority of cases (12/16, 75%). Per protocol, 57 patients (10%)were eligible to switch to FTC/TDF; the majority had HBV DNA <400 copies/mL at their last study visit regardless of whether they switched to FTC/TDF (n534) or maintained TDF monotherapy (n517). No patient exhibited persistent viremia (HBV DNA never <400 copies/mL) after week 240. CONCLUSION: TDF monotherapy maintains effective suppression of HBV DNA through 288 weeks of treatment with no evidence of TDF resistance.

Cyclosporin A and its analogs inhibit hepatitis B virus entry into cultured hepatocytes through targeting a membrane transporter, sodium taurocholate cotransporting polypeptide (NTCP).

UNLABELLED: Chronic hepatitis B virus (HBV) infection is a major public health problem worldwide. Although nucleos(t)ide analogs inhibiting viral reverse transcriptase are clinically available as anti-HBV agents, emergence of drug-resistant viruses highlights the need for new anti-HBV agents interfering with other targets. Here we report that cyclosporin A (CsA) can inhibit HBV entry into cultured hepatocytes. The anti-HBV effect of CsA was independent of binding to cyclophilin and calcineurin. Rather, blockade of HBV infection correlated with the ability to inhibit the transporter activity of sodium taurocholate cotransporting polypeptide (NTCP). We also found that HBV infection-susceptible cells, differentiated HepaRG cells and primary human hepatocytes expressed NTCP, while nonsusceptible cell lines did not. A series of compounds targeting NTCP could inhibit HBV infection. CsA inhibited the binding between NTCP and large envelope protein in vitro. Evaluation of CsA analogs identified a compound with higher anti-HBV potency, having a median inhibitory concentration <0.2 µM. CONCLUSION: This study provides a proof of concept for the novel strategy to identify anti-HBV agents by targeting the candidate HBV receptor, NTCP, using CsA as a structural platform.

SARS-CoV-2 viral dynamics in a placebo-controlled phase 2 study of patients infected with the SARS-CoV-2 Omicron variant and treated with pomotrelvir.

Current guidelines recommend that individuals with moderate COVID-19 disease isolate for 5 days after the first appearance of symptoms or a positive SARS-CoV-2 test. It would be useful to understand the time course of infectious virus production and its correlation with virus detection using a rapid antigen test (RAT) or quantitative reverse transcriptase (qRT)-PCR. In a phase 2 study, 242 vaccinated patients with COVID-19 and at low risk for progression to severe disease initiated 5 days of treatment with pomotrelvir (PBI-0451, a SARS-CoV-2 main protease inhibitor) or placebo within 5 days after symptom onset. The primary endpoint, the proportion of subjects with SARS-CoV-2 viral titers below the limit of detection on Day 3 of treatment in the pomotrelvir versus placebo groups, was not met. No between-group differences in SARS-CoV-2 clearance or symptom resolution or alleviation were observed. Additional analyses evaluated the dynamics of SARS-CoV-2 replication in mid-turbinate nasal swabs and saliva samples using infectious virus assay (IVA), RAT, and qRT-PCR. SARS-CoV-2 cleared rapidly, with negative results first determined by IVA (TCID50 below the limit of detection), followed by the RAT (negative for SARS-CoV-2 N antigen), and qRT-PCR (RNA below the limit of detection), which suggests that delayed initiation of treatment (up to 5 days after symptom onset) may have contributed to the lack of treatment response. Symptom resolution lagged behind viral clearance assessed by IVA and RAT. These data support reliance on a negative RAT to determine when an individual is no longer producing infectious virus and may end isolation.IMPORTANCEA phase 2 double-blind, placebo-controlled study was performed evaluating pomotrelvir, a SARS-CoV-2 Mpro inhibitor, compared with placebo in 242 non-hospitalized, vaccinated, symptomatic adults with COVID-19 (Omicron). No improvement in the decrease of viral replication or relief of symptoms was observed between the two groups when treatment was initiated ≥3 days after symptom onset. These results suggest that future COVID-19 antiviral studies using a similar patient population may need to initiate treatment earlier, like influenza studies. This is the first study to prospectively evaluate SARS-CoV-2 viral dynamics and the time to viral clearance in a significant number of patients using concurrently obtained results from an infectious virus assay, a rapid antigen test (RAT), and a qRT-PCR assay over a 15-day time course. These results suggest that a negative RAT assay is a good indicator of loss of infectious virus and the ability to return to normal activities.

Similar evolution of hepatitis B virus quasispecies in patients with incomplete adefovir response receiving tenofovir/emtricitabine combination or tenofovir monotherapy.

BACKGROUND & AIMS: Adefovir (ADV) resistance mutations induce low-level cross-resistance to tenofovir in vitro. Our aim was to compare viral kinetics, nucleos(t)ide analog resistance mutations, and quasispecies (QS) evolution during therapy with tenofovir disoproxil fumarate (TDF) or emtricitabine + TDF (FTC/TDF) in selected patients with incomplete ADV responses. METHODS: Patients with chronic hepatitis B and incomplete response to ADV were randomized in a double-blind trial of TDF vs. FTC/TDF. Extensive analysis of QS evolution was performed in 17 patients through 48 weeks of treatment. RESULTS: At week 24, 48% of patients (9/17) achieved HBV DNA undetectability (<69 IU/ml) with no difference between treatment groups. ADV and/or LAM resistance mutations were detected in all 17 patients at baseline and in 5/6 analyzable patients at week 48. A total of 1224 reverse transcriptase clones were analyzed. Clonal analysis revealed no significant difference at baseline in QS complexity or diversity between treatment groups. There was a trend in both treatment groups for an increase in QS complexity at week 12, followed by a decrease in complexity and diversity by week 48. Analysis of individual patients showed no consistent selection/accumulation of specific viral resistance patterns during treatment, but at week 48, mutations at rtA181 persisted in 4 patients. CONCLUSIONS: TDF or FTC/TDF demonstrated strong viral suppression in patients with an incomplete response to ADV and no significant selective pressure on pre-existing ADV or LAM resistant strains. TDF monotherapy and FTC/TDF combination therapy had a comparable impact on QS evolution.

Evaluation of anti-HBV drug resistant mutations among patients with acute symptomatic hepatitis B in the United States.

BACKGROUND & AIMS: Reported HBV drug resistance mutations among previously untreated patients with chronic hepatitis B are variable. Whether resistant HBV strains are transmitted in the acute setting is uncertain. We sought to document the presence of antiviral resistance (AVR) mutations in patients with acute HBV (AHB) infection. METHODS: AHB infection was defined by HBsAg/IgM anti-HBc positivity, ALT>10X ULN and compatible clinical history. The TRUGENE HBV kit was used to perform genotyping and direct sequencing of the viral polymerase. INNO-LiPA HBV DRv2 and DRv3 were used to detect AVR mutations. Clonal sequencing was conducted on selected specimens. RESULTS: Twenty-three patients were evaluated (mean age, 43 years; 54% male; 39% African American, 39% Caucasian, 13% Hispanic and 4% Asian). The mean peak ALT was 1554.2IU/L and mean peak total serum bilirubin was 12 mg/dl. The HBV DNA median viral load (N = 15) was 5.14 log(10)IU/ml. Nineteen patients were genotype A, and 1 each were genotype C, D, E and G. HBV drug resistance mutations were not detected by direct sequencing or INNO-LiPA. Clonal sequencing was conducted on 192 clones isolated from three patients and showed rtA181T, rtM250V and rtS202G mutations at an overall frequency of 1.54%, 1.39%, and 1.67% respectively. CONCLUSIONS: We detected adefovir/lamivudine and entecavir relevant mutations in a minor population (<2%) of viral clones by clonal sequencing only. The clinical significance of these mutations is uncertain and may represent small populations of quasi-species vs. transmission of drug resistant strains.