Diverse psychotropic substances detected in drug and drug administration equipment samples submitted to drug checking services in Toronto, Ontario, Canada, October 2019–April 2020

Background The overdose crisis has generated innovative harm reduction and drug market monitoring strategies. In Toronto, Ontario, Canada, a multi-site drug checking service (DCS) pilot project was launched in October 2019. The project provides people who use drugs with information on the chemical composition of their substances, thereby increasing their capacity to make more informed decisions about their drug use and avoid overdose. DCS also provides real-time market monitoring to identify trends in the unregulated drug supply. Methods Sample data were obtained through analyses of drug and used drug administration equipment samples submitted anonymously and free of charge to DCS in downtown Toronto from October 10, 2019, to April 9, 2020, representing the first six months of DCS implementation. Analyses were conducted in clinical laboratories using liquid chromatography- and/or gas chromatography-mass spectrometry (LC–MS, GC–MS) techniques. Results Overall, 555 samples were submitted, with 49% (271) of samples that were found to contain high-potency opioids, of which 87% (235) also contained stimulants. Benzodiazepine-type drugs were found in 21% (116) of all samples, and synthetic cannabinoids in 1% (7) of all samples. Negative effects (including overdose, adverse health events, and extreme sedation) were reported for 11% (59) of samples submitted for analysis. Conclusions Toronto’s DCS identified a range of high-potency opioids with stimulants, benzodiazepine-type drugs, and a synthetic cannabinoid, AMB-FUBINACA. This information can inform a range of evidence-informed overdose prevention efforts.

Structural insights into the potency and selectivity of covalent pan-FGFR inhibitors

FIIN-2, TAS-120 (Futibatinib) and PRN1371 are highly potent pan-FGFR covalent inhibitors targeting the p-loop cysteine of FGFR proteins, of which TAS-120 and PRN1371 are currently in clinical trials. It is critical to analyze their target selectivity and their abilities to overcome gatekeeper mutations. In this study, we demonstrate that FIIN-2 and TAS-120 form covalent adducts with SRC, while PRN1371 does not. FIIN-2 and TAS-120 inhibit SRC and YES activities, while PRN1371 does not. Moreover, FIIN-2, TAS-120 and PRN1371 exhibit different potencies against different FGFR gatekeeper mutants. In addition, the co-crystal structures of SRC/FIIN-2, SRC/TAS-120 and FGFR4/PRN1371 complexes reveal structural basis for kinase targeting and gatekeeper mutations. Taken together, our study not only provides insight into the potency and selectivity of covalent pan-FGFR inhibitors, but also sheds light on the development of next-generation FGFR covalent inhibitors with high potency, high selectivity, and stronger ability to overcome gatekeeper mutations.

Delta infection following vaccination elicits potent neutralizing immunity against the SARS-CoV-2 Omicron

Since the initial detection of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant (B.1.1.529) in November 2021 in South Africa, it has caused a rapid increase in infections globally. The Omicron variant encodes 37 amino acid substitutions in its spike protein, and early reports have provided evidence for extensive immune escape and reduced vaccine effectiveness. We assessed serum neutralizing activity in sera from Delta infection following vaccination of CoronaVac or ZF2001 and Delta infection only against SARS-CoV-2 Wuhan-Hu-1 (WA1), Beta, Delta, and Omicron. We found that sera from Delta infection only could neutralize WA1 and Delta pseudoviruses but nearly completely lost capacity to neutralize Beta and Omicron pseudoviruses. However, Delta infection following vaccination resulted in a significant increase of serum neutralizing activity against WA1, Beta, and Omicron. This study demonstrates that breakthrough infection of Delta in previously vaccinated individuals substantially induced high potency humoral immune response against the Omicron variant and other emerged variants.

Probing the structure and function of the protease domain of botulinum neurotoxins using single-domain antibodies

Botulinum neurotoxins (BoNTs) are among the deadliest of bacterial toxins. BoNT serotype A and B in particular pose the most serious threat to humans because of their high potency and persistence. To date, there is no effective treatment for late post-exposure therapy of botulism patients. Here, we aim to develop single-domain variable heavy-chain (VHH) antibodies targeting the protease domains (also known as the light chain, LC) of BoNT/A and BoNT/B as antidotes for post-intoxication treatments. Using a combination of X-ray crystallography and biochemical assays, we investigated the structures and inhibition mechanisms of a dozen unique VHHs that recognize four and three non-overlapping epitopes on the LC of BoNT/A and BoNT/B, respectively. We show that the VHHs that inhibit the LC activity occupy the extended substrate-recognition exosites or the cleavage pocket of LC/A or LC/B and thus block substrate binding. Notably, we identified several VHHs that recognize highly conserved epitopes across BoNT/A or BoNT/B subtypes, suggesting that these VHHs exhibit broad subtype efficacy. Further, we identify two novel conformations of the full-length LC/A, that could aid future development of inhibitors against BoNT/A. Our studies lay the foundation for structure-based engineering of protein- or peptide-based BoNT inhibitors with enhanced potencies and cross-subtypes properties.

Influence of age and ways of treatment in the parasitemia in mice infected with Trypanosoma cruzi treated with high potency biotherapy

Introduction: The infection of mice by Trypanosoma cruzi is well known, making this a good model for understanding the effect of highly diluted medications. Mice of different ages show different responses to biotherapic T. cruzi [1]. Other data from our laboratory using biotherapic treatment at low potencies show that long lasting treatment has a better effect in mice infected with T. cruzi. However, the use of high potency biotherapics in mice of different ages infected with T. cruzi has not been analysed yet. Aim: To evaluate the effect of different ways of treatment using biotherapic 200 DH T. cruzi in the evolution of the curve of parasitemia of mice of different ages infected with T. cruzi. Materials and methods: A blind randomized controlled trial was performed using 107 swiss male mice, aged 28, 35 and 56 days, divided into groups: CONTROL(C) – mice aged 28(C28), 38(C38) and 56(C56) days, treated with 7% water-alcohol solution diluted with water (1mL/100mL); ONE DAY(OD) – mice aged 28(OD28), 38(OD38) and 56(OD56) days, treated with highly diluted medication 200 DH T. cruzi in a single dose, diluted in water (10mL/100mL); EVERY DAY(ED) – mice aged 28(ED28), 38(ED38) and 56(ED56) days, treated with highly diluted medication 200DH T.cruzi until the end of the experiment, diluted in water(1mL/100mL). Amber bottle was used and the water was changed every two days. The groups were infected with strain Y-T. cruzi, intraperitoneal,1400 blood trypomastigotes. Medicines were handled according to the Brazilian Homeopathic Pharmacopoeia [2], with microbiological testing according to RDC n° 67 and in vivo biological risk. We compared the parasitemia curve and total parasitemia, determined daily counting of the parasites [3], obtained using the tests Kruskal-Wallis and Wald-Wolfowitz, Statistica 8.0, 5% significance. Approved by the Ethics Committee for Animal Experimentation/ UEM - 030/2008. Results: The animal age and the ways of treatment used influenced the evolution of the parasitemia curve. This evolution was different among different ages, and the youngest mice of the control group had higher averages of parasitemia ( C28=1.4x106/mL; C38= 1.3 x106/mL and C56=1.0x106/mL ) (fig1). This evolution was not observed in the groups treated daily, in which 56 day-old mice presented a higher parasitemia compared to the other groups ( ED28= 1.3x106/mL; ED38=0.9x106/mL and ED56=1.2x106/mL )(fig1b). For animals treated with a single dose, the energetic stimulus provided by biotherapic caused homogeneity of biological behavior, with significant elevation of parasitemia ( OD28=1.8x106/mL; OD38=1.3x106/mL and OD56=1.5 x106/mL) (fig1c). Likewise, the single dose treatment invariably resulted in an increase of parasitemia when compared to other treatments within the same age group (fig1d-f). The treatment performed daily in animals aged 28 and 38 days showed a decrease in parasitemia (fig1d-f). For 56 day-old mice this fall was not observed (fig1f). The meaning of this finding should be better explored considering the physiological maturity versus the vital energy of mice of different ages. Conclusion: The age and the ways of treatment used are important factors to be considered when using a highly diluted medication. The clinical use of these results in humans, should take into consideration the allometric system of medication dosage which takes into account the metabolic rate of each organism.

Using antibody synergy to engineer a high potency biologic cocktail against C. difficile

We applied a mathematical framework originally used to model the effects of multiple inhibitors on enzyme activity to guide the development a therapeutic antibody cocktail, LMN-201, to prevent and treat C. difficile infection (CDI). CDI causes hundreds of thousands of cases of severe, often recurrent diarrhea and colitis in the United States annually and is associated with significant morbidity and mortality worldwide. Current therapies for preventing recurrent CDI are only partially successful, and there are no options available to prevent initial bouts of CDI in at-risk populations. Almost all antibody therapies have been developed and administered as monotherapies. Antibody cocktails are relatively rare even though they have the potential to greatly increase efficacy. One reason for this is our limited understanding of how antibody interactions can enhance potency, which makes it difficult to identify and develop antibodies that can be assembled into optimally effective cocktails. In contrast to the view that antibody synergies depend on unusual instances of cooperativity or allostery, we show that synergistic efficacy requires nothing more than that the antibodies bind independently to distinct epitopes on a common target. Therefore, synergy may be achieved much more readily than is generally appreciated. Due to synergy the LMN-201 antibody cocktail, which targets the C. difficile exotoxin B (TcdB), is 300- to 3000-fold more potent at neutralizing the most clinically prevalent TcdB toxin types than bezlotoxumab, the only monoclonal antibody currently approved for treatment or prevention of CDI. The efficacy of LMN-201 is further enhanced by inclusion of a phage-derived endolysin that destroys the C. difficile bacterium, and which therefore has a complementary mechanism of action to the antibody cocktail. These observations may serve as a paradigm for the development of high potency biologic cocktails against targets that have proven challenging for single-agent therapies.

From Crystal Structures of RgIA4 in Complex with Ac-AChBP to Molecular Determinants of Its High Potency of α9α10 nAChR

α9-containing nicotinic acetylcholine receptors (nAChRs) have been shown to play critical roles in neuropathic pain. The α-conotoxin (α-CTx) RgIA and its analog RgIA4 were identified as the most selective inhibitor of α9α10 nAChR. However, the mechanism of their selectivity toward α9α10 nAChR remains elusive. Here, we reported the co-crystal structure of RgIA and RgIA4 in complex with Aplysia californica acetylcholine binding protein (Ac-AChBP) at resolution of 2.6 Å, respectively. Based on the structure of the complexes, together with molecular dynamic simulation (MD-simulation), we suggested the key residues of α9α10 nAChR in determining its high affinity for RgIA/RgIA4. This is the first time the complex between pain-related conotoxins and Ac-AChBP was reported and the complementary side of α9 subunit in binding of the antagonists shown. These results provide realistic template for the design of new therapeutic in neuropathic pain.