TVB-2640 (FASN Inhibitor) for the Treatment of Nonalcoholic Steatohepatitis: FASCINATE-1, a Randomized, Placebo-Controlled Phase 2a Trial.

BACKGROUND & AIMS: Increased de novo lipogenesis creates excess intrahepatic fat and lipotoxins, propagating liver damage in nonalcoholic steatohepatitis. TVB-2640, a fatty acid synthase inhibitor, was designed to reduce excess liver fat and directly inhibit inflammatory and fibrogenic pathways. We assessed the safety and efficacy of TVB-2640 in patients with nonalcoholic steatohepatitis in the United States. METHODS: 3V2640-CLIN-005 (FASCINATE-1) was a randomized, placebo-controlled, single-blind study at 10 US sites. Adults with ≥8% liver fat, assessed by magnetic resonance imaging proton density fat fraction, and evidence of liver fibrosis by magnetic resonance elastography ≥2.5 kPa or liver biopsy were eligible. Ninety-nine patients were randomized to receive placebo or 25 mg or 50 mg of TVB-2640 (orally, once-daily for 12 weeks). The primary end points of this study were safety and relative change in liver fat after treatment. RESULTS: Liver fat increased in the placebo cohort by 4.5% relative to baseline; in contrast TVB-2640 reduced liver fat by 9.6% in the 25-mg cohort (n = 30; least squares mean: -15.5%; 95% confidence interval, -31.3 to -0.23; P = .053), and 28.1% in the 50-mg cohort (n = 28; least squares mean: -28.0%; 95% confidence interval, -44.5 to -11.6; P = .001). Eleven percent of patients in the placebo group achieved a ≥30% relative reduction of liver fat compared to 23% in the 25-mg group, and 61% in the 50-mg group (P < .001). Secondary analyses showed improvements of metabolic, pro-inflammatory and fibrotic markers. TVB-2640 was well tolerated; adverse events were mostly mild and balanced among the groups. CONCLUSIONS: TVB-2640 significantly reduced liver fat and improved biochemical, inflammatory, and fibrotic biomarkers after 12 weeks, in a dose-dependent manner in patients with nonalcoholic steatohepatitis. ClinicalTrials.gov, Number NCT03938246.

Fatty Acid Synthase Inhibitor TVB-2640 Reduces Hepatic de Novo Lipogenesis in Males With Metabolic Abnormalities.

BACKGROUND AND AIMS: Elevated hepatic de novo lipogenesis (DNL) is a key distinguishing characteristic of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis. In rodent models of NAFLD, treatment with a surrogate of TVB-2640, a pharmacological fatty acid synthase inhibitor, has been shown to reduce hepatic fat and other biomarkers of DNL. The purpose of this phase I clinical study was to test the effect of the TVB-2640 in obese men with certain metabolic abnormalities that put them at risk for NAFLD. APPROACH AND RESULTS: Twelve subjects (mean ± SEM, 42 ± 2 years, body mass index 37.4 ± 1.2 kg/m2 , glucose 103 ± 2 mg/dL, triacylglycerols 196 ± 27 mg/dL, and elevated liver enzymes) underwent 10 days of treatment with TVB-2640 at doses ranging from 50-150 mg/day. Food intake was controlled throughout the study. Hepatic DNL was measured before and after an oral fructose/glucose bolus using isotopic labeling with 1-13 C1 -acetate intravenous infusion, followed by measurement of labeled very low-density lipoprotein palmitate via gas chromatography mass spectometry. Substrate oxidation was measured by indirect calorimetry. Across the range of doses, fasting DNL was reduced by up to 90% (P = 0.003). Increasing plasma concentrations of TVB-2640 were associated with progressive reductions in the percent of fructose-stimulated peak fractional DNL (R2  = -0.749, P = 0.0003) and absolute DNL area under the curve 6 hours following fructose/glucose bolus (R2  = -0.554, P = 0.005). For all subjects combined, alanine aminotransferase was reduced by 15.8 ± 8.4% (P = 0.05). Substrate oxidation was unchanged, and safety monitoring revealed that the drug was well tolerated, without an increase in plasma triglycerides. Alopecia occurred in 2 subjects (reversed after stopping the drug), but otherwise no changes were observed in fasting glucose, insulin, ketones, and renal function. CONCLUSION: These data support the therapeutic potential of a fatty acid synthase inhibitor, TVB-2640 in particular, in patients with NAFLD and nonalcoholic steatohepatitis.

Genomic analysis of chimeric human cytomegalovirus vaccine candidates derived from strains Towne and Toledo.

Human cytomegalovirus (HCMV) is an important opportunistic pathogen in immunocompromised patients and a major cause of congenital birth defects when acquired in utero. In the 1990s, four chimeric viruses were constructed by replacing genome segments of the high passage Towne strain with segments of the low passage Toledo strain, with the goal of obtaining live attenuated vaccine candidates that remained safe but were more immunogenic than the overly attenuated Towne vaccine. The chimeras were found to be safe when administered to HCMV-seronegative human volunteers, but to differ significantly in their ability to induce seroconversion. This suggests that chimera-specific genetic differences impacted the ability to replicate or persist in vivo and the consequent ability to induce an antibody response. To identify specific genomic breakpoints between Towne and Toledo sequences and establish whether spontaneous mutations or rearrangements had occurred during construction of the chimeras, complete genome sequences were determined. No major deletions or rearrangements were observed, although a number of unanticipated mutations were identified. However, no clear association emerged between the genetic content of the chimeras and the reported levels of vaccine-induced HCMV-specific humoral or cellular immune responses, suggesting that multiple genetic determinants are likely to impact immunogenicity. In addition to revealing the genome organization of the four vaccine candidates, this study provided an opportunity to probe the genetics of HCMV attenuation in humans. The results may be valuable in the future design of safe live or replication-defective vaccines that optimize immunogenicity and efficacy.

A Phase 1 Study of 4 Live, Recombinant Human Cytomegalovirus Towne/Toledo Chimera Vaccines in Cytomegalovirus-Seronegative Men.

BACKGROUND: Human cytomegalovirus (HCMV) infection causes disease in newborns and transplant recipients. A HCMV vaccine (Towne) protects transplant recipients. METHODS: The genomes of Towne and the nonattenuated Toledo strain were recombined, yielding 4 Towne/Toledo chimera vaccines. Each of 36 HCMV-seronegative men received 1 subcutaneous dose of 10, 100, or 1000 plaque-forming units (PFU) in cohorts of 3. Safety and immunogenicity were evaluated over 12 weeks after immunization and for 52 weeks for those who seroconverted. RESULTS: There were no serious local or systemic reactions. No subject had HCMV in urine or saliva. For chimera 3, none of 9 subjects seroconverted. For chimera 1, 1 of 9 seroconverted (the seroconverter received 100 PFU). For chimera 2, 3 subjects seroconverted (1 received 100 PFU, and 2 received 1000 PFU). For chimera 4, 7 subjects seroconverted (1 received 10 PFU, 3 received 100 PFU, and 3 received 1000 PFU). All 11 seroconverters developed low but detectable levels of neutralizing activity. CD4+ T-cell responses were detectable in 1 subject (who received 100 PFU of chimera 4). Seven subjects receiving chimera 2 or 4 had detectable CD8+ T-cell responses to IE1; 3 responded to 1-2 additional antigens. CONCLUSIONS: The Towne/Toledo chimera vaccine candidates were well tolerated and were not excreted. Additional human trials of chimeras 2 and 4 are appropriate. CLINICAL TRIALS REGISTRATION: NCT01195571.

Evaluation of three live attenuated H2 pandemic influenza vaccine candidates in mice and ferrets.

UNLABELLED: H2 influenza viruses have not circulated in humans since 1968, and therefore a significant portion of the population would be susceptible to infection should H2 influenza viruses reemerge. H2 influenza viruses continue to circulate in avian reservoirs worldwide, and these reservoirs are a potential source from which these viruses could emerge. Three reassortant cold-adapted (ca) H2 pandemic influenza vaccine candidates with hemagglutinin (HA) and neuraminidase (NA) genes derived from the wild-type A/Japan/305/1957 (H2N2) (Jap/57), A/mallard/6750/1978 (H2N2) (mal/78), or A/swine/MO/4296424/2006 (H2N3) (sw/06) viruses and the internal protein gene segments from the A/Ann Arbor/6/60 ca virus were generated by plasmid-based reverse genetics (Jap/57 ca, mal/78 ca, and sw/06 ca, respectively). The vaccine candidates exhibited the in vitro phenotypes of temperature sensitivity and cold adaptation and were restricted in replication in the respiratory tract of ferrets. In mice and ferrets, the vaccines elicited neutralizing antibodies and conferred protection against homologous wild-type virus challenge. Of the three candidates, the sw/06 ca vaccine elicited cross-reactive antibodies and provided significant protection against the greatest number of heterologous viruses. These observations suggest that the sw/06 ca vaccine should be further evaluated in a clinical trial as an H2 pandemic influenza vaccine candidate. IMPORTANCE: Influenza pandemics arise when novel influenza viruses are introduced into a population with little prior immunity to the new virus and often result in higher rates of illness and death than annual seasonal influenza epidemics. An influenza H2 subtype virus caused a pandemic in 1957, and H2 viruses circulated in humans till 1968. H2 influenza viruses continue to circulate in birds, and the development of an H2 influenza vaccine candidate is therefore considered a priority in preparing for future pandemics. However, we cannot predict whether a human H2 virus will reemerge or a novel avian H2 virus will emerge. We identified three viruses as suitable candidates for further evaluation as vaccines to protect against H2 influenza viruses and evaluated the immune responses and protection that these three vaccines provided in mice and ferrets.

African green monkeys recapitulate the clinical experience with replication of live attenuated pandemic influenza virus vaccine candidates.

Live attenuated cold-adapted (ca) H5N1, H7N3, H6N1, and H9N2 influenza vaccine viruses replicated in the respiratory tract of mice and ferrets, and 2 doses of vaccines were immunogenic and protected these animals from challenge infection with homologous and heterologous wild-type (wt) viruses of the corresponding subtypes. However, when these vaccine candidates were evaluated in phase I clinical trials, there were inconsistencies between the observations in animal models and in humans. The vaccine viruses did not replicate well and immune responses were variable in humans, even though the study subjects were seronegative with respect to the vaccine viruses before vaccination. Therefore, we sought a model that would better reflect the findings in humans and evaluated African green monkeys (AGMs) as a nonhuman primate model. The distribution of sialic acid (SA) receptors in the respiratory tract of AGMs was similar to that in humans. We evaluated the replication of wt and ca viruses of avian influenza (AI) virus subtypes H5N1, H6N1, H7N3, and H9N2 in the respiratory tract of AGMs. All of the wt viruses replicated efficiently, while replication of the ca vaccine viruses was restricted to the upper respiratory tract. Interestingly, the patterns and sites of virus replication differed among the different subtypes. We also evaluated the immunogenicity and protective efficacy of H5N1, H6N1, H7N3, and H9N2 ca vaccines. Protection from wt virus challenge correlated well with the level of serum neutralizing antibodies. Immune responses were slightly better when vaccine was delivered by both intranasal and intratracheal delivery than when it was delivered intranasally by sprayer. We conclude that live attenuated pandemic influenza virus vaccines replicate similarly in AGMs and human subjects and that AGMs may be a useful model to evaluate the replication of ca vaccine candidates. Importance: Ferrets and mice are commonly used for preclinical evaluation of influenza vaccines. However, we observed significant inconsistencies between observations in humans and in these animal models. We used African green monkeys (AGMs) as a nonhuman primate (NHP) model for a comprehensive and comparative evaluation of pairs of wild-type and pandemic live attenuated influenza virus vaccines (pLAIV) representing four subtypes of avian influenza viruses and found that pLAIVs replicate similarly in AGMs and humans and that AGMs can be useful for evaluation of the protective efficacy of pLAIV.

Pharmacological induction of membrane lipid poly-unsaturation sensitizes melanoma to ROS inducers and overcomes acquired resistance to targeted therapy.

BACKGROUND: One of the key limitations of targeted cancer therapies is the rapid onset of therapy resistance. Taking BRAF-mutant melanoma as paradigm, we previously identified the lipogenic regulator SREBP-1 as a central mediator of resistance to MAPK-targeted therapy. Reasoning that lipogenesis-mediated alterations in membrane lipid poly-unsaturation lie at the basis of therapy resistance, we targeted fatty acid synthase (FASN) as key player in this pathway to evoke an exquisite vulnerability to clinical inducers of reactive oxygen species (ROS), thereby rationalizing a novel clinically actionable combination therapy to overcome therapy resistance. METHODS: Using gene expression analysis and mass spectrometry-based lipidomics of BRAF-mutant melanoma cell lines, melanoma PDX and clinical data sets, we explored the association of FASN expression with membrane lipid poly-unsaturation and therapy-resistance. Next, we treated therapy-resistant models with a preclinical FASN inhibitor TVB-3664 and a panel of ROS inducers and performed ROS analysis, lipid peroxidation tests and real-time cell proliferation assays. Finally, we explored the combination of MAPK inhibitors, TVB-3664 and arsenic trioxide (ATO, as a clinically used ROS-inducer) in Mel006 BRAF mutant PDX as a gold model of therapy resistance and assessed the effect on tumor growth, survival and systemic toxicity. RESULTS: We found that FASN expression is consistently increased upon the onset of therapy resistance in clinical melanoma samples, in cell lines and in Mel006 PDX and is associated with decreased lipid poly-unsaturation. Forcing lipid poly-unsaturation in therapy-resistant models by combining MAPK inhibition with FASN inhibition attenuated cell proliferation and rendered cells exquisitely sensitive to a host of ROS inducers. In particular, the triple combination of MAPK inhibition, FASN inhibition, and the clinical ROS-inducing compound ATO dramatically increased survival of Mel006 PDX models from 15 to 72% with no associated signs of toxicity. CONCLUSIONS: We conclude that under MAPK inhibition the direct pharmacological inhibition of FASN evokes an exquisite vulnerability to inducers of ROS by increasing membrane lipid poly-unsaturation. The exploitation of this vulnerability by combining MAPK and/or FASN inhibitors with inducers of ROS greatly delays the onset of therapy resistance and increases survival. Our work identifies a clinically actionable combinatorial treatment for therapy-resistant cancer.

Comparison of a live attenuated 2009 H1N1 vaccine with seasonal influenza vaccines against 2009 pandemic H1N1 virus infection in mice and ferrets.

The role of seasonal influenza vaccination in pandemic influenza A H1N1 disease is important to address, because a large segment of the population is vaccinated annually. We administered 1 or 2 doses of pandemic H1N1 vaccine (CA/7 ca), a seasonal trivalent inactivated (s-TIV), or live attenuated influenza vaccine (s-LAIV) to mice and ferrets and subsequently challenged them with a pandemic H1N1 virus. In both species, CA/7 ca was immunogenic and conferred complete protection against challenge. s-TIV did not confer protection in either animal model, and s-LAIV did not confer any protection in ferrets. In mice, 2 doses of s-LAIV led to complete protection in the upper respiratory tract and partial protection in the lungs. Our data indicate that vaccination with the seasonal influenza vaccines did not confer complete protection in the lower respiratory tract in either animal model, whereas the CA/7 ca vaccine conferred complete protection in both animal models.

FASN inhibition targets multiple drivers of NASH by reducing steatosis, inflammation and fibrosis in preclinical models.

Fatty acid synthase (FASN) is an attractive therapeutic target in non-alcoholic steatohepatitis (NASH) because it drives de novo lipogenesis and mediates pro-inflammatory and fibrogenic signaling. We therefore tested pharmacological inhibition of FASN in human cell culture and in three diet induced mouse models of NASH. Three related FASN inhibitors were used; TVB-3664, TVB-3166 and clinical stage TVB-2640 (denifanstat). In human primary liver microtissues, FASN inhibiton (FASNi) decreased triglyceride (TG) content, consistent with direct anti-steatotic activity. In human hepatic stellate cells, FASNi reduced markers of fibrosis including collagen1α (COL1α1) and α-smooth muscle actin (αSMA). In CD4+ T cells exposed to NASH-related cytokines, FASNi decreased production of Th17 cells, and reduced IL-1ß release in LPS-stimulated PBMCs. In mice with diet induced NASH l, FASNi prevented development of hepatic steatosis and fibrosis, and reduced circulating IL-1ß. In mice with established diet-induced NASH, FASNi reduced NAFLD activity score, fibrosis score, ALT and TG levels. In the CCl4-induced FAT-NASH mouse model, FASN inhibition decreased hepatic fibrosis and fibrosis markers, and development of hepatocellular carcinoma (HCC) tumors by 85%. These results demonstrate that FASN inhibition attenuates inflammatory and fibrotic drivers of NASH by direct inhibition of immune and stellate cells, beyond decreasing fat accumulation in hepatocytes. FASN inhibition therefore provides an opportunity to target three key hallmarks of NASH.

Targeting de novo lipogenesis and the Lands cycle induces ferroptosis in KRAS-mutant lung cancer.

Mutant KRAS (KM), the most common oncogene in lung cancer (LC), regulates fatty acid (FA) metabolism. However, the role of FA in LC tumorigenesis is still not sufficiently characterized. Here, we show that KMLC has a specific lipid profile, with high triacylglycerides and phosphatidylcholines (PC). We demonstrate that FASN, the rate-limiting enzyme in FA synthesis, while being dispensable in EGFR-mutant or wild-type KRAS LC, is required for the viability of KMLC cells. Integrating lipidomic, transcriptomic and functional analyses, we demonstrate that FASN provides saturated and monounsaturated FA to the Lands cycle, the process remodeling oxidized phospholipids, such as PC. Accordingly, blocking either FASN or the Lands cycle in KMLC, promotes ferroptosis, a reactive oxygen species (ROS)- and iron-dependent cell death, characterized by the intracellular accumulation of oxidation-prone PC. Our work indicates that KM dictates a dependency on newly synthesized FA to escape ferroptosis, establishing a targetable vulnerability in KMLC.

Evaluation of replication and cross-reactive antibody responses of H2 subtype influenza viruses in mice and ferrets.

H2 influenza viruses have not circulated in humans since 1968, and therefore a large segment of the population would likely be susceptible to infection should H2 influenza viruses reemerge. The development of an H2 pandemic influenza virus vaccine candidate should therefore be considered a priority in pandemic influenza preparedness planning. We selected a group of geographically and temporally diverse wild-type H2 influenza viruses and evaluated the kinetics of replication and compared the ability of these viruses to induce a broadly cross-reactive antibody response in mice and ferrets. In both mice and ferrets, A/Japan/305/1957 (H2N2), A/mallard/NY/1978 (H2N2), and A/swine/MO/2006 (H2N3) elicited the broadest cross-reactive antibody responses against heterologous H2 influenza viruses as measured by hemagglutination inhibition and microneutralization assays. These data suggested that these three viruses may be suitable candidates for development as live attenuated H2 pandemic influenza virus vaccines.

A live attenuated H7N7 candidate vaccine virus induces neutralizing antibody that confers protection from challenge in mice, ferrets, and monkeys.

A live attenuated H7N7 candidate vaccine virus was generated by reverse genetics using the modified hemagglutinin (HA) and neuraminidase (NA) genes of highly pathogenic (HP) A/Netherlands/219/03 (NL/03) (H7N7) wild-type (wt) virus and the six internal protein genes of the cold-adapted (ca) A/Ann Arbor/6/60 ca (AA ca) (H2N2) virus. The reassortant H7N7 NL/03 ca vaccine virus was temperature sensitive and attenuated in mice, ferrets, and African green monkeys (AGMs). Intranasal (i.n.) administration of a single dose of the H7N7 NL/03 ca vaccine virus fully protected mice from lethal challenge with homologous and heterologous H7 viruses from Eurasian and North American lineages. Two doses of the H7N7 NL/03 ca vaccine induced neutralizing antibodies in serum and provided complete protection from pulmonary replication of homologous and heterologous wild-type H7 challenge viruses in mice and ferrets. One dose of the H7N7 NL/03 ca vaccine elicited an antibody response in one of three AGMs that was completely protected from pulmonary replication of the homologous wild-type H7 challenge virus. The contribution of CD8(+) and/or CD4(+) T cells to the vaccine-induced protection of mice was evaluated by T-cell depletion; T lymphocytes were not essential for the vaccine-induced protection from lethal challenge with H7 wt viruses. Additionally, passively transferred neutralizing antibody induced by the H7N7 NL/03 ca virus protected mice from lethality following challenge with H7 wt viruses. The safety, immunogenicity, and efficacy of the H7N7 NL/03 ca vaccine virus in mice, ferrets, and AGMs support the evaluation of this vaccine virus in phase I clinical trials.

Glycosylation at 158N of the hemagglutinin protein and receptor binding specificity synergistically affect the antigenicity and immunogenicity of a live attenuated H5N1 A/Vietnam/1203/2004 vaccine virus in ferrets.

A live attenuated influenza A/Vietnam/1203/2004 (H5N1) vaccine virus (VN04 ca) has receptor binding specificity to alpha2,3-linked sialosides (alpha2,3SAL), and a single dose induces a minimal serum antibody response in mice and ferrets. In contrast, A/Hong Kong/213/2003 (H5N1) vaccine virus (HK03 ca) binds to both alpha2,6SAL and alpha2,3SAL and generates a stronger serum antibody response in animals. Among the 9 amino acids that differed between the two H5 HA1 proteins, several HK03-specific residues enabled the VN04 ca virus to bind to both alpha2,3SAL and alpha2,6SAL receptors, but only the removal of the 158N glycosylation, together with an S227N change, resulted in more-efficient viral replication in the upper respiratory tract of ferrets and an increased serum antibody response. However, the antibody response was HK03 strain specific and did not significantly cross-neutralize VN04 virus. A second approach was taken to adapt the H5N1 VN04 ca virus in MDCK cells to select HA variants with larger plaque morphology. Although a number of large-plaque-size HA variants with amino acid changes in the HA receptor binding region were identified, none of these mutations affected virus receptor binding preference and immunogenicity. In addition, the known receptor binding site changes, Q226L and G228S, were introduced into the HA protein of the VN04 ca virus. Only in conjunction with the removal of the 158N glycosylation did the virus replicate efficiently in the upper respiratory tract of ferrets and became more immunogenic, yet the response was also HK03 specific. Thus, the mask of the antigenic epitopes by 158N glycosylation at the HA globular head and its alpha2,3SAL binding preference of VN04 ca virus affect virus antigenicity and replication in the host, resulting in a lower antibody response.

Generation of live attenuated novel influenza virus A/California/7/09 (H1N1) vaccines with high yield in embryonated chicken eggs.

Several live attenuated influenza virus A/California/7/09 (H1N1) (CA09) candidate vaccine variants that possess the hemagglutinin (HA) and neuraminidase (NA) gene segments from the CA09 virus and six internal protein gene segments from the cold-adapted influenza virus A/Ann Arbor/6/60 (H2N2) virus were generated by reverse genetics. The reassortant viruses replicated relatively poorly in embryonated chicken eggs. To improve virus growth in eggs, reassortants expressing the HA and NA of CA09 were passaged in MDCK cells and variants exhibiting large-plaque morphology were isolated. These variants replicated at levels approximately 10-fold higher than the rate of replication of the parental strains in embryonated chicken eggs. Sequence analysis indicated that single amino acid changes at positions 119, 153, 154, and 186 were responsible for the improved growth properties in MDCK cells and eggs. In addition, the introduction of a mutation at residue 155 that was previously shown to enhance the replication of a 1976 swine influenza virus also significantly improved the replication of the CA09 virus in eggs. Each variant was further evaluated for receptor binding preference, antigenicity, attenuation phenotype, and immunogenicity. Mutations at residues 153, 154, and 155 drastically reduced viral antigenicity, which made these mutants unsuitable as vaccine candidates. However, changes at residues 119 and 186 did not affect virus antigenicity or immunogenicity, justifying their inclusion in live attenuated vaccine candidates to protect against the currently circulating 2009 swine origin H1N1 viruses.

Fatty acid synthase (FASN) regulates the mitochondrial priming of cancer cells.

Inhibitors of the lipogenic enzyme fatty acid synthase (FASN) have attracted much attention in the last decade as potential targeted cancer therapies. However, little is known about the molecular determinants of cancer cell sensitivity to FASN inhibitors (FASNis), which is a major roadblock to their therapeutic application. Here, we find that pharmacological starvation of endogenously produced FAs is a previously unrecognized metabolic stress that heightens mitochondrial apoptotic priming and favors cell death induction by BH3 mimetic inhibitors. Evaluation of the death decision circuits controlled by the BCL-2 family of proteins revealed that FASN inhibition is accompanied by the upregulation of the pro-death BH3-only proteins BIM, PUMA, and NOXA. Cell death triggered by FASN inhibition, which causally involves a palmitate/NADPH-related redox imbalance, is markedly diminished by concurrent loss of BIM or PUMA, suggesting that FASN activity controls cancer cell survival by fine-tuning the BH3 only proteins-dependent mitochondrial threshold for apoptosis. FASN inhibition results in a heightened mitochondrial apoptosis priming, shifting cells toward a primed-for-death state "addicted" to the anti-apoptotic protein BCL-2. Accordingly, co-administration of a FASNi synergistically augments the apoptosis-inducing activity of the dual BCL-XL/BCL-2 inhibitor ABT-263 (navitoclax) and the BCL-2 specific BH3-mimetic ABT-199 (venetoclax). FASN inhibition, however, fails to sensitize breast cancer cells to MCL-1- and BCL-XL-selective inhibitors such as S63845 and A1331852. A human breast cancer xenograft model evidenced that oral administration of the only clinically available FASNi drastically sensitizes FASN-addicted breast tumors to ineffective single-agents navitoclax and venetoclax in vivo. In summary, a novel FASN-driven facet of the mitochondrial priming mechanistically links the redox-buffering mechanism of FASN activity to the intrinsic apoptotic threshold in breast cancer cells. Combining next-generation FASNis with BCL-2-specific BH3 mimetics that directly activate the apoptotic machinery might generate more potent and longer-lasting antitumor responses in a clinical setting.

First-in-human study of the safety, pharmacokinetics, and pharmacodynamics of first-in-class fatty acid synthase inhibitor TVB-2640 alone and with a taxane in advanced tumors.

BACKGROUND: We conducted a first-in-human dose-escalation study with the oral FASN inhibitor TVB-2640 to determine the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D), as monotherapy and with a taxane. METHODS: This completed open-label outpatient study was conducted at 11 sites in the United States and United Kingdom. Patients with previously-treated advanced metastatic solid tumors and adequate performance status and organ function were eligible. TVB-2640 was administered orally daily until PD. Dose escalation initially followed an accelerated titration design that switched to a standard 3 + 3 design after Grade 2 toxicity occurred. Disease-specific cohorts were enrolled at the MTD. Statistical analyses were primarily descriptive. Safety analyses were performed on patients who received at least 1 dose of study drug. (Clinicaltrials.gov identifier NCT02223247). FINDINGS: The study was conducted from 21 November 2013 to 07 February 2017. Overall, 136 patients received TVB-2640, 76 as monotherapy (weight-based doses of 60 mg/m2 to 240 mg/m2 and flat doses of 200 and 250 mg) and 60 in combination, (weight-based doses of 60 mg/m2 to 100 mg/m2 and flat dose of 200 mg) (55 paclitaxel, 5 docetaxel). DLTs with TVB-2640 were reversible skin and ocular effects. The MTD/RP2D was 100 mg/m2. The most common TEAEs (n,%) with TVB-2640 monotherapy were alopecia (46; 61%), PPE syndrome (35; 46%), fatigue (28; 37%), decreased appetite (20; 26%), and dry skin (17; 22%), and with TVB-2640+paclitaxel were fatigue (29 ; 53%), alopecia (25; 46%), PPE syndrome (25; 46%), nausea (22; 40%), and peripheral neuropathy (20; 36%). One fatal case of drug-related pneumonitis occurred with TVB-2640+paclitaxel; no other treatment-related deaths occurred. Target engagement (FASN inhibition) and inhibition of lipogenesis were demonstrated with TVB-2640. The disease control rate (DCR) with TVB-2640 monotherapy was 42%; no patient treated with monotherapy had a complete or partial response (CR or PR). In combination with paclitaxel, the PR rate was 11% and the DCR was 70%. Responses were seen across multiple tumor types, including in patients with KRASMUT NSCLC, ovarian, and breast cancer. INTERPRETATION: TVB-2640 demonstrated potent FASN inhibition and a predictable and manageable safety profile, primarily characterized by non-serious, reversible adverse events affecting skin and eyes. Further investigation of TVB-2640 in patients with solid tumors, particularly in KRASMUT lung, ovarian, and breast cancer, is warranted. FUNDING: This trial was funded by 3-V Biosciences, Inc. (now known as Sagimet Biosciences Inc.).

Live attenuated versus inactivated influenza vaccine in infants and young children.

BACKGROUND: Universal vaccination of children 6 to 59 months of age with trivalent inactivated influenza vaccine has recently been recommended by U.S. advisory bodies. To evaluate alternative vaccine approaches, we compared the safety and efficacy of intranasally administered live attenuated influenza vaccine with those of inactivated vaccine in infants and young children. METHODS: Children 6 to 59 months of age, without a recent episode of wheezing illness or severe asthma, were randomly assigned in a 1:1 ratio to receive either cold-adapted trivalent live attenuated influenza vaccine (a refrigeration-stable formulation of live attenuated intranasally administered influenza vaccine) or trivalent inactivated vaccine in a double-blind manner. Influenza-like illness was monitored with cultures throughout the 2004-2005 influenza season. RESULTS: Safety data were available for 8352 children, and 7852 children completed the study according to the protocol. There were 54.9% fewer cases of cultured-confirmed influenza in the group that received live attenuated vaccine than in the group that received inactivated vaccine (153 vs. 338 cases, P<0.001). The superior efficacy of live attenuated vaccine, as compared with inactivated vaccine, was observed for both antigenically well-matched and drifted viruses. Among previously unvaccinated children, wheezing within 42 days after the administration of dose 1 was more common with live attenuated vaccine than with inactivated vaccine, primarily among children 6 to 11 months of age; in this age group, 12 more episodes of wheezing were noted within 42 days after receipt of dose 1 among recipients of live attenuated vaccine (3.8%) than among recipients of inactivated vaccine (2.1%, P=0.076). Rates of hospitalization for any cause during the 180 days after vaccination were higher among the recipients of live attenuated vaccine who were 6 to 11 months of age (6.1%) than among the recipients of inactivated vaccine in this age group (2.6%, P=0.002). CONCLUSIONS: Among young children, live attenuated vaccine had significantly better efficacy than inactivated vaccine. An evaluation of the risks and benefits indicates that live attenuated vaccine should be a highly effective, safe vaccine for children 12 to 59 months of age who do not have a history of asthma or wheezing. (ClinicalTrials.gov number, NCT00128167 [ClinicalTrials.gov].).

Evaluation of live attenuated influenza a virus h6 vaccines in mice and ferrets.

Avian influenza A virus A/teal/HK/W312/97 (H6N1) possesses seven gene segments that are highly homologous to those of highly pathogenic human influenza H5N1 viruses, suggesting that a W312-like H6N1 virus might have been involved in the generation of the A/HK/97 H5N1 viruses. The continuous circulation and reassortment of influenza H6 subtype viruses in birds highlight the need to develop an H6 vaccine to prevent potential influenza pandemics caused by the H6 viruses. Based on the serum antibody cross-reactivity data obtained from 14 different H6 viruses from Eurasian and North American lineages, A/duck/HK/182/77, A/teal/HK/W312/97, and A/mallard/Alberta/89/85 were selected to produce live attenuated H6 candidate vaccines. Each of the H6 vaccine strains is a 6:2 reassortant ca virus containing HA and NA gene segments from an H6 virus and the six internal gene segments from cold-adapted A/Ann Arbor/6/60 (AA ca), the master donor virus that is used to make live attenuated influenza virus FluMist (intranasal) vaccine. All three H6 vaccine candidates exhibited phenotypic properties of temperature sensitivity (ts), ca, and attenuation (att) conferred by the internal gene segments from AA ca. Intranasal administration of a single dose of the three H6 ca vaccine viruses induced neutralizing antibodies in mice and ferrets and fully protected mice and ferrets from homologous wild-type (wt) virus challenge. Among the three H6 vaccine candidates, the A/teal/HK/W312/97 ca virus provided the broadest cross-protection against challenge with three antigenically distinct H6 wt viruses. These data support the rationale for further evaluating the A/teal/HK/W312/97 ca vaccine in humans.

Nasal turbinate enlargement due to cartilage and bone proliferation: a normal developmental finding in young ferrets.

Toxicity studies of intranasally administered, live attenuated influenza virus vaccine candidates conducted in male and female ferrets led to the microscopic observation of individual differences in the size of nasal turbinates, especially in the dorsal aspect of the nasal cavity. The association of these enlarged turbinates with acute to subacute inflammation, which is sometimes common in ferrets given live attenuated influenza virus vaccine candidates, led to this detailed microscopic evaluation of turbinate enlargement (cartilaginous and osseous thickening, or COT) in control animals dosed intranasally with saline. Results of this evaluation led to the conclusion that COT is a normal developmental feature of growing ferrets, irrespective of inflammation in nasal tissues or inflammatory exudate in the nasal cavity.

Avian influenza h6 viruses productively infect and cause illness in mice and ferrets.

Influenza pandemic preparedness has focused on influenza virus H5 and H7 subtypes. However, it is not possible to predict with certainty which subtype of avian influenza virus will cause the next pandemic, and it is prudent to include other avian influenza virus subtypes in pandemic preparedness efforts. An H6 influenza virus was identified as a potential progenitor of the H5N1 viruses that emerged in Hong Kong in 1997. This virus continues to circulate in the bird population in Asia, and other H6 viruses are prevalent in birds in North America and Asia. The high rate of reassortment observed in influenza viruses and the prevalence of H6 viruses in birds suggest that this subtype may pose a pandemic risk. Very little is known about the replicative capacity, immunogenicity, and correlates of protective immunity for low-pathogenicity H6 influenza viruses in mammals. We evaluated the antigenic and genetic relatedness of 14 H6 influenza viruses and their abilities to replicate and induce a cross-reactive immune response in two animal models: mice and ferrets. The different H6 viruses replicated to different levels in the respiratory tracts of mice and ferrets, causing varied degrees of morbidity and mortality in these two models. H6 virus infection induced similar patterns of neutralizing antibody responses in mice and ferrets; however, species-specific differences in the cross-reactivity of the antibody responses were observed. Overall, cross-reactivity of neutralizing antibodies in H6 virus-infected mice did not correlate well with protection against heterologous wild-type H6 viruses. However, we have identified an H6 virus that induces protective immunity against viruses in the North American and Eurasian lineages.