In May 2020 the Russian Ministry of Health granted fast-track marketing authorization to RNA polymerase inhibitor AVIFAVIR (favipiravir) for the treatment of COVID-19 patients. In the pilot stage of Phase II/III clinical trial, AVIFAVIR enabled SARS-CoV-2 viral clearance in 62.5% of patients within 4 days, and was safe and well-tolerated.

In May 2020 the Russian Ministry of Health granted fast-track marketing authorization to RNA polymerase inhibitor AVIFAVIR (favipiravir) for the treatment of COVID-19 patients. In the pilot stage of Phase II/III clinical trial, AVIFAVIR enabled SARS-CoV-2 viral clearance in 62.5% of patients within 4 days, and was safe and well-tolerated.

A series of next in class small-molecule hepatitis C virus (HCV) NS5A inhibitors with picomolar potency containing 2-pyrrolidin-2-yl-5-{4-[4-(2-pyrrolidin-2-yl-1H-imidazol-5-yl)buta-1,3-diynyl]phenyl}-1H-imidazole cores was designed based on the SAR studies available for the reported NS5A inhibitors. Compound 13a (AV4025), with (S,S,S,S)-stereochemistry (EC50 = 3.4 ± 0.2 pM, HCV replicon genotype 1b), was dramatically more active than were the compounds with two (S)- and two (R)-chiral centers. Human serum did not significantly reduce the antiviral activity (<4-fold). Relatively favorable pharmacokinetic features and good oral bioavailability were observed during animal studies. Compound 13a was well tolerated in rodents (in mice, LD50 = 2326 mg/kg or higher), providing a relatively high therapeutic index. During safety, pharmacology and subchronic toxicity studies in rats and dogs, it was not associated with any significant pathological or clinical findings. This compound is currently being evaluated in phase I/II clinical trials for the treatment of HCV infection.

It was a negative study with unexpected benefits of the drug only in females. We hypothesized that the role of patients' sex can impact the treatment response to serotonergic drugs in general. We suggest a possible synergistic interaction between estrogen and Avisetron by means of modulating the effect of estrogens on the serotonergic system. Future studies targeting the sex-related effects of serotonergic drugs are warranted.

5541 Background: Quisinostat is an orally bioavailable potent pan-histone deacetylase inhibitor. Combinations of HDAC inhibitors with paclitaxel or cisplatin demonstrate promising results in preclinical models with cisplatin and paclitaxel resistant OC. In phase Ib study the dosage of Quisinostat in combination of paclitaxel and carboplatin recommended for the phase II study was 12 mg. We report results of the phase II study of Quisinostat in combination with paclitaxel and carboplatin in pts with recurrent platinum resistantOC. Methods: the main inclusion criteria was tumor progression observed not less than 1 month and no more than 6 months after completion of the planned number of cycles of 1st line platinum/paclitaxel based CT. Quisinostat was administered at dose 12 mg p.o. each 3 week cycle on Days 1, 3, 5, 7, 9, 11 with of paclitaxel (175 mg/m2) and carboplatin (AUC5) on Day 7 of each cycle, for 2ndline. Pts received up to 6 cycles. The primary efficacy endpoint is the objective response rate (ORR) verified by the ICR. The secondary endpoints include safety, progression free survival (PFS) and overall survival. The study design implies the use of the two-stage Simon model: 29 patients who underwent treatment would provide 80% power for hypothesis testing in order to frequency of the ORR 30% (α = 0.05). Results: 31 pts were enrolled (30 pts evaluated). Median age was 57 years. Twenty one pts (67.7%) received all 6 cycles of therapy. ORR was 50.0% (15 pts). Median duration of response was 5 months (4.2-5.7). Median PFS - 6 months (95%CI 4.4-7.6). Any SAE were seen in 16.1% pts, AE of grade 3 and 4 – in 71% and 48.4% pts temporarily discontinued therapy due to AE. Dose reduction of CT due to AE was performed in 22.6% pts. The most common adverse events were neutropenia – 67,7%, nausea – 61.3%, weakness – 29%, thrombocytopenia – 22.6%, neuropathy – 19.4%, vomiting – 19.4%. Conclusions: Quisinostat in combination with paclitaxel and carboplatin in pts with recurrent platinum resistant ovarian cancer showed high efficacy and good tolerability Clinical trial information: NCT02948075.