Nirmatrelvir treatment of SARS-CoV-2-infected mice blunts antiviral adaptive immune responses.

Alongside vaccines, antiviral drugs are becoming an integral part of our response to the SARS-CoV-2 pandemic. Nirmatrelvir-an orally available inhibitor of the 3-chymotrypsin-like cysteine protease-has been shown to reduce the risk of progression to severe COVID-19. However, the impact of nirmatrelvir treatment on the development of SARS-CoV-2-specific adaptive immune responses is unknown. Here, by using mouse models of SARS-CoV-2 infection, we show that nirmatrelvir administration blunts the development of SARS-CoV-2-specific antibody and T cell responses. Accordingly, upon secondary challenge, nirmatrelvir-treated mice recruited significantly fewer memory T and B cells to the infected lungs and mediastinal lymph nodes, respectively. Together, the data highlight a potential negative impact of nirmatrelvir treatment with important implications for clinical management and might help explain the virological and/or symptomatic relapse after treatment completion reported in some individuals.

Oral Nirmatrelvir for High-Risk, Nonhospitalized Adults with Covid-19.

BACKGROUND: Nirmatrelvir is an orally administered severe acute respiratory syndrome coronavirus 2 main protease (Mpro) inhibitor with potent pan-human-coronavirus activity in vitro. METHODS: We conducted a phase 2-3 double-blind, randomized, controlled trial in which symptomatic, unvaccinated, nonhospitalized adults at high risk for progression to severe coronavirus disease 2019 (Covid-19) were assigned in a 1:1 ratio to receive either 300 mg of nirmatrelvir plus 100 mg of ritonavir (a pharmacokinetic enhancer) or placebo every 12 hours for 5 days. Covid-19-related hospitalization or death from any cause through day 28, viral load, and safety were evaluated. RESULTS: A total of 2246 patients underwent randomization; 1120 patients received nirmatrelvir plus ritonavir (nirmatrelvir group) and 1126 received placebo (placebo group). In the planned interim analysis of patients treated within 3 days after symptom onset (modified intention-to treat population, comprising 774 of the 1361 patients in the full analysis population), the incidence of Covid-19-related hospitalization or death by day 28 was lower in the nirmatrelvir group than in the placebo group by 6.32 percentage points (95% confidence interval [CI], -9.04 to -3.59; P<0.001; relative risk reduction, 89.1%); the incidence was 0.77% (3 of 389 patients) in the nirmatrelvir group, with 0 deaths, as compared with 7.01% (27 of 385 patients) in the placebo group, with 7 deaths. Efficacy was maintained in the final analysis involving the 1379 patients in the modified intention-to-treat population, with a difference of -5.81 percentage points (95% CI, -7.78 to -3.84; P<0.001; relative risk reduction, 88.9%). All 13 deaths occurred in the placebo group. The viral load was lower with nirmatrelvir plus ritonavir than with placebo at day 5 of treatment, with an adjusted mean difference of -0.868 log10 copies per milliliter when treatment was initiated within 3 days after the onset of symptoms. The incidence of adverse events that emerged during the treatment period was similar in the two groups (any adverse event, 22.6% with nirmatrelvir plus ritonavir vs. 23.9% with placebo; serious adverse events, 1.6% vs. 6.6%; and adverse events leading to discontinuation of the drugs or placebo, 2.1% vs. 4.2%). Dysgeusia (5.6% vs. 0.3%) and diarrhea (3.1% vs. 1.6%) occurred more frequently with nirmatrelvir plus ritonavir than with placebo. CONCLUSIONS: Treatment of symptomatic Covid-19 with nirmatrelvir plus ritonavir resulted in a risk of progression to severe Covid-19 that was 89% lower than the risk with placebo, without evident safety concerns. (Supported by Pfizer; ClinicalTrials.gov number, NCT04960202.).

The oral protease inhibitor (PF-07321332) protects Syrian hamsters against infection with SARS-CoV-2 variants of concern.

There is an urgent need for potent and selective antivirals against SARS-CoV-2. Pfizer developed PF-07321332 (PF-332), a potent inhibitor of the viral main protease (Mpro, 3CLpro) that can be dosed orally and that is in clinical development. We here report that PF-332 exerts equipotent in vitro activity against the four SARS-CoV-2 variants of concerns (VoC) and that it can completely arrest replication of the alpha variant in primary human airway epithelial cells grown at the air-liquid interface. Treatment of Syrian Golden hamsters with PF-332 (250 mg/kg, twice daily) completely protected the animals against intranasal infection with the beta (B.1.351) and delta (B.1.617.2) SARS-CoV-2 variants. Moreover, treatment of SARS-CoV-2 (B.1.617.2) infected animals with PF-332 completely prevented transmission to untreated co-housed sentinels.

Evaluation of the absolute oral bioavailability of the anaplastic lymphoma kinase/c-ROS oncogene 1 kinase inhibitor lorlatinib in healthy participants.

PURPOSE: Lorlatinib is a third-generation tyrosine kinase inhibitor currently approved for the treatment of anaplastic lymphoma kinase (ALK)-positive metastatic non-small cell lung cancer. This open-label, phase 1, randomized two-sequence, two-treatment, two-period, crossover study investigated the absolute oral bioavailability of lorlatinib in healthy participants. METHODS: Eligible participants were randomized to receive two treatments in one of two sequences: lorlatinib 100 mg single oral dose followed by lorlatinib 50 mg intravenous (IV) dose, or lorlatinib IV dose followed by lorlatinib oral dose, each with at least a 10-day washout between successive lorlatinib doses. Blood samples for pharmacokinetics were collected for up to 144 hours (h) after dosing. Validated liquid chromatographic-tandem mass spectrometry was used to determine plasma concentrations of lorlatinib and its benzoic acid metabolite PF-06895751. RESULTS: In total, 11 participants were enrolled (mean age 37.6 years, all male). The adjusted geometric mean (90% confidence interval) for the absolute oral bioavailability was 80.78% (75.73-86.16%). Using non-compartmental analysis, the estimated arithmetic mean elimination plasma half-life of lorlatinib was 25.5 and 27.0 h after the oral and IV doses, respectively. No deaths, serious adverse events (AEs), or severe AEs were reported, and most treatment-emergent AEs were mild in severity, with two events of transaminase increase of moderate severity. All treatment-emergent AEs were resolved by the end of the study. CONCLUSION: Both oral and IV lorlatinib were well-tolerated in healthy participants and oral lorlatinib is highly bioavailable after oral administration.

An oral SARS-CoV-2 Mpro inhibitor clinical candidate for the treatment of COVID-19.

The worldwide outbreak of COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global pandemic. Alongside vaccines, antiviral therapeutics are an important part of the healthcare response to countering the ongoing threat presented by COVID-19. Here, we report the discovery and characterization of PF-07321332, an orally bioavailable SARS-CoV-2 main protease inhibitor with in vitro pan-human coronavirus antiviral activity and excellent off-target selectivity and in vivo safety profiles. PF-07321332 has demonstrated oral activity in a mouse-adapted SARS-CoV-2 model and has achieved oral plasma concentrations exceeding the in vitro antiviral cell potency in a phase 1 clinical trial in healthy human participants.

Selective MOR activity of DAPEA and Endomorphin-2 analogues containing a (R)-γ-Freidinger lactam in position two.

The use of α-amino-γ lactam of Freidinger (Agl) may serve as an impressive method to increase the biological stability of peptides and an appropriate tool to elucidate their structure-activity relationships. The endomorphin-2 (EM-2) and [D-Ala2, des-Leu5] enkephalin amide (DAPEA) are two linear opioid tetrapeptides agonists of MOR and MOR/DOR respectively. Herein, we investigated the influence of the incorporation of (R/S)-Agl in position 2 and 3 on the biological profile of the aforementioned products in vitro and in vivo. Receptor radiolabeled displacement and functional assays were used to measure in vitro the binding affinity and receptors activation of the novel analogues. The mouse tail flick and formalin tests allowed to observe their antinociceptive effect in vivo. Data revealed that peptide A2D was able to selectively bind and activate MOR with a potent antinociceptive effect after intracerebroventricular (i.c.v.) administration, performing better than the parent compounds EM-2 and DAPEA. Molecular docking calculations helped us to understand the key role exerted by the Freidinger Agl moiety in A2D for the interaction with the MOR binding pocket.

Differential Inhibition of Equilibrative Nucleoside Transporter 1 (ENT1) Activity by Tyrosine Kinase Inhibitors.

BACKGROUND AND OBJECTIVES: Equilibrative nucleoside transporter (ENT) 1 is a widely-expressed drug transporter, handling nucleoside analogues as well as endogenous nucleosides. ENT1 has been postulated to be inhibited by some marketed tyrosine kinase inhibitors (TKIs). To obtain insights into this point, the interactions of 24 TKIs with ENT1 activity have been analyzed. METHODS: Inhibition of ENT1 activity was investigated in vitro through quantifying the decrease of [3H]-uridine uptake caused by TKIs in HAP1 ENT2-knockout cells, exhibiting selective ENT1 expression. TKI effects towards ENT1-mediated transport were additionally characterized in terms of their in vivo relevance and of their relationship to TKI molecular descriptors. Putative transport of the TKI lorlatinib by ENT1/ENT2 was analyzed by LC-MS/MS. RESULTS: Of 24 TKIs, 12 of them, each used at 10 µM, were found to behave as moderate or strong inhibitors of ENT1, i.e., they decreased ENT1 activity by at least 35%. This inhibition was concentration-dependent for at least the strongest ones (IC50 less than 10 µM) and was correlated with some molecular descriptors, especially with atom-type E-state indices. Lorlatinib was notably a potent in vitro inhibitor of ENT1/ENT2 (IC50 values around 1.0-2.5 µM) and was predicted to inhibit these nucleoside transporters at relevant clinical concentrations, without, however, being a substrate for them. CONCLUSION: Our data unambiguously add ENT1 to the list of drug transporters inhibited by TKIs, especially by lorlatinib. This point likely merits attention in terms of possible drug-drug interactions, notably for nucleoside analogues, whose ENT1-mediated uptake into their target cells may be hampered by co-administrated TKIs such as lorlatinib.

Real-world efficacy and safety of lorlatinib in treating advanced ALK-positive non-small cell lung cancer patients.

Anaplastic lymphoma kinase (ALK) translocation is a rare driver mutation in lung cancer. This study was aimed to report on the efficacy of lorlatinib in real-world practice and to evaluate the impact of prior ALK inhibitor treatments. We retrospectively evaluated patients with ALK-positive non-small cell lung cancer (NSCLC) treated with lorlatinib regarding its efficacy, the impact of prior ALK inhibitor treatments and the adverse events, in particular dyslipidemia. A total of 22 ALK-positive patients were analyzed. All patients had received at least one second-generation ALK inhibitor(s), while 12 patients had a history of crizotinib treatment. For lorlatinib, the objective response rate was 35.7%, and disease control rate was 64.3%. Their progression-free survival (PFS) was 6.2 months. With prior therapies, patients receiving only second-generation ALK inhibitor(s) treatment showed PFS longer than those with both crizotinib and second-generation ALK inhibitor(s) treatments (15.2 vs. 6.2 months). Moreover, patients who showed benefits from prior ALK inhibitor(s) also had a PFS longer than those who did not (6.5 vs. 3.5 months). Regarding adverse events, 94.7% of patients had dyslipidemia and 21.1% of them were in grade 3 or 4. None of these patients discontinued the treatment due to dyslipidemia. No acute complication occurred with dyslipidemia. The real-world efficacy of lorlatinib and adverse events were similar to those reported in clinical trials. Interestingly, the history and responses of prior ALK inhibitor treatments may influence the efficacy of subsequent lorlatinib treatment.

Population pharmacokinetic model with time-varying clearance for lorlatinib using pooled data from patients with non-small cell lung cancer and healthy participants.

Lorlatinib, a selective inhibitor of anaplastic lymphoma kinase (ALK) and c-ROS oncogene 1 (ROS1) tyrosine kinase, is indicated for the treatment of ALK-positive metastatic non-small cell lung cancer (NSCLC) following progression on crizotinib and at least one other ALK inhibitor, or alectinib/ceritinib as the first ALK inhibitor therapy for metastatic disease. The population pharmacokinetics (PopPK) of lorlatinib was conducted by nonlinear mixed effects modeling of data from 330 patients with ALK-positive or ROS1-positive NSCLC and 95 healthy participants from six phase I studies in healthy volunteers; demographic, metabolizer phenotype, and patient prognostic factors were evaluated as covariates. Lorlatinib plasma PK was well-characterized by a two-compartment model with sequential zero-order and first-order absorption and a time-varying induction of clearance. Single dose clearance was estimated to be 9.04 L/h. Assuming that the metabolic auto-induction of lorlatinib reaches saturation in ~ 5 half-lives, clearance was estimated to approach a maximum of 14.5 L/h at steady-state after a period of ~ 7.25 days. The volume of distribution of the central compartment was estimated to be 121 L and the first-order absorption rate constant was estimated to be 3.1 h-1 . Baseline albumin and lorlatinib total daily dose were significant covariates on lorlatinib clearance. Use of proton pump inhibitors was found to be a significant covariate on the lorlatinib absorption rate constant. These factors were assessed to have no clinically meaningful impact on lorlatinib plasma exposure, and no dose adjustments are considered necessary based on the examined covariates.

Targeting eIF4F translation initiation complex with SBI-756 sensitises B lymphoma cells to venetoclax.

BACKGROUND: The BCL2 inhibitor venetoclax has shown efficacy in several hematologic malignancies, with the greatest response rates in indolent blood cancers such as chronic lymphocytic leukaemia. There is a lower response rate to venetoclax monotherapy in diffuse large B-cell lymphoma (DLBCL). METHODS: We tested inhibitors of cap-dependent mRNA translation for the ability to sensitise DLBCL and mantle cell lymphoma (MCL) cells to apoptosis by venetoclax. We compared the mTOR kinase inhibitor (TOR-KI) MLN0128 with SBI-756, a compound targeting eukaryotic translation initiation factor 4G1 (eIF4G1), a scaffolding protein in the eIF4F complex. RESULTS: Treatment of DLBCL and MCL cells with SBI-756 synergised with venetoclax to induce apoptosis in vitro, and enhanced venetoclax efficacy in vivo. SBI-756 prevented eIF4E-eIF4G1 association and cap-dependent translation without affecting mTOR substrate phosphorylation. In TOR-KI-resistant DLBCL cells lacking eIF4E binding protein-1, SBI-756 still sensitised to venetoclax. SBI-756 selectively reduced translation of mRNAs encoding ribosomal proteins and translation factors, leading to a reduction in protein synthesis rates in sensitive cells. When normal lymphocytes were treated with SBI-756, only B cells had reduced viability, and this correlated with reduced protein synthesis. CONCLUSIONS: Our data highlight a novel combination for treatment of aggressive lymphomas, and establishes its efficacy and selectivity using preclinical models.

Inflammatory Myofibroblastic Tumor of the Bladder With FN1-ALK Gene Fusion: Different Response to ALK Inhibition.

Inflammatory myofibroblastic tumors are rare tumors with an ALK (anaplastic lymphoma kinase) gene rearrangement in up to 65% of all cases. In our patient, the tumor was not primary resectable due to its extension. Under neoadjuvant treatment with the first generation ALK inhibitor crizotinib no tumor response was seen, but the following therapy with the next generation ALK inhibitor lorlatinib led to a rapid and deep response, enabling a complete tumor resection by partial cystectomy. Our case indicates that ALK positive inflammatory myofibroblastic tumors which do not respond to ALK inhibition with crizotinib can be successfully treated with newer agents.

(-)-Clausenamide alleviated ER stress and apoptosis induced by OGD/R in primary neuron cultures.

OBJECTIVE: The endoplasmic reticulum stress (ERS) and ERS-related neuronal apoptosis contribute to the cerebral ischemia/reperfusion (I/R) injury. (-)-Clausenamide has been reported to be nootropic and improve learning and memory in amnesia animal models. However, whether (-)-Clau could protect neurons from ischemic injury and the possible mechanism needed further study. The present study aimed to explore the effects of (-)-Clau on primary cortical neurons treated with oxygen-glucose deprivation/reoxygenation (OGD/R). METHODS: Rat primary cortical neurons were used to set up an injury model of OGD/R which imitated the clinical I/R injury. Cell viability and apoptosis were measured by CCK-8 assay, LDH detection and TUNEL staining, respectively. The activation of GRP78/eIF2α-ATF4-CHOP signaling pathway, one of the three branches of ERS, and cleaved caspase-3, the apoptotic marker, were assessed by western blotting. RESULTS: OGD/R induced activation of GRP78/eIF2α-ATF4-CHOP signaling pathway. (-)-Clau significantly attenuated OGD/R-induced decrease in the cellular viability and the activation of GRP78, eIF2α, ATF4 and CHOP. To further confirm the effect of (-)-Clau on OGD/R-induced ERS activation, the ERS inducer Tunicamycin (TM) was applied. TM significantly abolished (-)-Clau's protective effect against ERS and neuronal apoptosis, indicating that the protective effect of (-)-Clau was dependent on inhibiting ERS. CONCLUSIONS: The present work demonstrated for the first time that (-)-Clau could reverse the activation of GRP78/eIF2α-ATF4-CHOP branch, thus inhibited ERS and the subsequent apoptosis induced by OGD/R and promoted cell viability in vitro. (-)-Clau could serve as a promising therapeutic agent in the treatment for ischemic stroke in the future. ABBREVIATIONS: ATF4: activating transcription factor-4; ATF6: activating transcription factor-6; CHOP: transcriptional induction of CCAAT/enhancer binding protein homologous protein; (-)-Clau: 3-hydroxy-4-phenyl-5a-hydroxybenzylN-methyl-g-lactam; eIF2α: eukaryotic initiation factor 2α; ER: endoplasmic reticulum; ERS: endoplasmic reticulum stress; GRP78: 78-kDa glucose regulated protein; I/R: ischemia/reperfusion; IRE1: inositol requiring enzyme-1; JNK: c-Jun N-terminal kinase; OGD/R: oxygen-glucose deprivation/reoxygenation; PERK: double-stranded RNA-dependent protein kinase-like ER kinase; TM: Tunicamycin; UPR: unfolded protein response.

Discovery of steroidal lactam conjugates of POPAM-NH2 with potent anticancer activity.

Aim: Steroidal prodrugs of nitrogen mustards such as estramustine and prednimustine have proven effective anticancer agents in clinical use since the 1970s. In this work, we aimed to develop steroidal prodrugs of the novel nitrogen mustard POPAM-NH2. POPAM-NH2 is a melphalan analogue that was coupled with three different steroidal lactams. Methodology: The new conjugates were preclinically tested for anticancer activity against nine human and one rodent cancer experimental models, in vitro and in vivo. Results & conclusion: All the steroidal alkylators showed high antitumor activity, in vitro and in vivo, in the experimental systems tested. Moreover, these hybrid compounds showed by far superior anticancer activity compared with the alkylating agents, melphalan and POPAM-NH2.

Evaluation of thioamides, thiolactams and thioureas as hydrogen sulfide (H2S) donors for lowering blood pressure.

Hydrogen sulfide (H2S) is a biologically important gaseous molecule that exhibits promising protective effects against a variety of pathological processes. For example, it was recognized as a blood pressure lowering agent. Aligned with the need for easily modifiable platforms for the H2S supply, we report here the preparation and the H2S release kinetics from a series of structurally diversified thioamides, thiolactams and thioureas. Three different thionation methods based on the usage of a phosphorus pentasulfide and Lawesson reagent were applied to prepare the target thioamides and thiolactams. Furthermore, obtained H2S donors were evaluated both in in vivo and in vitro studies. The kinetic parameters of the liberating H2S was determined and compared with NaHS and GYY4137 using two different detection technics i.e.; fluorescence labeling 7-azido-4-methyl-2H-chromen-2-one and 5,5'-dithiobis (2-nitrobenzoic acid), sulfhydryl probe, also known as the Ellman's reagent. We have proved that the amount of releasing H2S from these compounds is controllable through structural modifications. Finally, the present study shows a hypotensive response to an intravenous administration of the developed donors in the anesthetized rats.

Twelve-week ravidasvir plus ritonavir-boosted danoprevir and ribavirin for non-cirrhotic HCV genotype 1 patients: A phase 2 study.

BACKGROUND AND AIM: The need for all-oral hepatitis C virus (HCV) treatments with higher response rates, improved tolerability, and lower pill burden compared with interferon-inclusive regimen has led to the development of new direct-acting antiviral agents. Ravidasvir (RDV) is a second-generation, pan-genotypic NS5A inhibitor with high barrier to resistance. The aim of this phase 2 study (EVEREST study) was to assess the efficacy and safety of interferon-free, 12-week RDV plus ritonavir-boosted danoprevir (DNVr) and ribavirin (RBV) regimen for treatment-naïve Asian HCV genotype 1 (GT1) patients without cirrhosis. METHODS: A total of 38 treatment-naïve, non-cirrhotic adult HCV GT1 patients were enrolled in this multicenter, open-label, single-arm phase 2 study (NCT03020095). All patients received a combination of RDV 200 mg once daily (q.d.) plus DNVr 100 mg/100 mg twice daily (b.i.d.) and oral RBV 1000/1200 mg/day (body weight < 75/≥ 75 kg) for 12 weeks. The primary endpoint was the rate of sustained virologic response 12 weeks after the end of treatment (SVR12). RESULTS: Of 38 patients, all (100%) achieved SVR12. During the study, no treatment-related serious adverse events, no patients discontinued treatment due to adverse events, and no deaths were reported. Six of 37 (16%) patients with available sequences had HCV NS5A resistance-associated variants at baseline. All patients (6/6) with baseline NS5A resistance-associated variants achieved SVR12. CONCLUSIONS: Twelve-week RDV and DNVr in combination with RBV for 12 weeks achieves the SVR12 rate of 100% in treatment-naïve non-cirrhotic Asian patients with HCV GT1 infection. This interferon-free regimen is also safe and well tolerated.