Comparative outcome of single versus two double-pigtail stents for endoscopic drainage of pancreatic fluid collections with minimal necrosis: a retrospective analysis

Background

Endoscopic ultrasound (EUS)-guided cystogastrostomy is the treatment of choice for managing symptomatic pancreatic fluid collections (PFC). However, studies on the number of stents for optimal drainage of PFCs are limited. Hence, the present study was conducted to compare the outcome of single versus two double-pigtail stents for endoscopic drainage of PFCs.

Methods

This is a single-center, retrospective analysis of patients undergoing endoscopic drainage of PFCs with minimal necrosis (pseudocyst or walled-off necrosis with <30% solid content) at a tertiary center in South India from October 2020 to October 2022. Post-procedure, patients were followed up for clinical improvement, and stents were removed after documentation of cyst size reduction on imaging.

Results

Sixty-three patients (82.5% males, median age: 34 years) fulfilling the selection criteria were included. For single stent placement (n = 47), stents of size 8.5 Fr or 10 Fr were used, while for placement of two stents (n = 16), 7 Fr stents were used. The technical success rate was 100%. Intraprocedural and early postprocedural adverse events (all mild to moderate) were comparable between the groups (17.0% with single stent vs. 25.0% with two stents, p = NS). Clinical success was achieved in 93.6% of patients, with no difference between both groups. Three patients in the single stent group required additional procedures. All patients underwent successful stent removal after a median follow-up of 14 weeks.

Conclusion

A single pigtail stent of 8.5 Fr or 10 Fr size for EUSguided cystogastrostomy provides efficacy and safety similar to that of two stents.

Abstract 3729: Discovery of orally bioavailable SMARCA2/4 dual degraders for treatment of acute myeloid leukemia

Background: The BAF (SWI/SNF) chromatin remodeling complex comprises of two mutually exclusive ATPases, SMARCA2 (BRM) and SMARCA4 (BRG1), that affect the mobilization and positioning of nucleosomes on DNA and thereby regulates important cellular functions including transcription, DNA recombination, DNA repair and chromosome decatenation during mitosis. SMARCA4 is frequently overexpressed in several types of cancers. Overexpression has been linked to increased proliferation and survival, as well as aggressive tumors and poor prognosis. SMARCA4 knockdown in these tumors lead to inhibition of proliferation and increased sensitivity to known chemotherapeutic agents, supporting the validity of targeting SMARCA4. Genetic silencing studies have established that the oncogenic activity of tumors lacking SMARCA4 is primarily driven by SMARCA2-containing residual SWI/SNF complex, suggesting the importance of dual inhibition of SMARCA2 and SMARCA4. While SMARCA4 is known to play a vital role in maintaining the oncogenic transcription program and driving proliferation in leukemia, the impact of dual SMARCA2 and SMARCA4 inhibition/degradation in acute myeloid leukemia (AML) is largely unexplored.

Methods and Results: As part of the initial design plan, selective SMARCA2/4 Bromodomain inhibitors and specific ligands of several E3 ligases were chosen to arrive at different degrader designs. A choice of linkers and different exit vectors were considered to construct a variety of hetero bifunctional molecules. Our proprietary ternary complex modeling algorithm, ALMOND (ALgorithm for MOdeling Neosubstrate Degraders) helped in prioritizing the designs. Short listed compounds were synthesized and profiled in multiple cellular assays to understand their degradation potential. Several compounds that degrade SMARCA2, SMARCA4 & PBRM1 with pico molar DC50 were identified. These compounds have shown very potent anti-proliferative activity in both SMARCA2/4 proficient (MV-4-11, VCaP etc) and SMARCA4 mutant cell lines (SK-MEL-5 & RERF-LC-A1 etc). Further, potent compounds were optimized for their pharmacokinetic properties. Multiple lead compounds with low IV clearance and good oral bioavailability in rodents were identified. Advanced lead compounds are currently being evaluated in rodent tolerability and PK-PD experiments to select doses for the efficacy study.

Conclusions: Highly potent degraders of SMARCA2, SMARCA4 & PBRM1 were identified by conjugating selective SMARCA2/4 Bromodomain inhibitors and several E3 ligase specific ligands. Further optimization of the linkers resulted in compounds with improved pharmacokinetic profile and very good oral bioavailability in rodents. Highly potent and orally available degraders of SMARCA2, SMARCA4 are efficacious in AML xenograft models and advanced profiling of candidate molecule is in progress.

Citation Format: Chandrasekhar Abbineni, Leena Khare, Bilash Kuila, Abdul Rawoof Khaji, Dhaytadak Bhagwan Mahadeo, Sandeep Vitthal Dukare, Bhagya M S Kumar, Suraj T Gore, Vijay Kamal Ahuja, Amit A Dhudashiya, Raghavendra N R, Nagesh Gowda, Charamanna K B, Kiran Aithal B, Samiulla D S, Subhendu Mukherjee, Thomas Antony, Sanjeev Giri, Shekar Chelur, Kavitha Nellore, Girish Daginakatte, Murali Ramachandra, Susanta Samajdar. Discovery of orally bioavailable SMARCA2/4 dual degraders for treatment of acute myeloid leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3729.

Exploration of the Plausible Mechanism of Ethambutol Induced Ocular Toxicity by Using Proteomics Informed Physiologically Based Pharmacokinetic (PBPK) Modeling

PURPOSE

Ethambutol (EMB) is a first-line anti-tubercular drug that is known to cause optic neuropathy. The exact mechanism of its eye toxicity is unknown; however, proposition is metal chelating effect of both EMB and its metabolite 2,2'-(ethylenediamino)-dibutyric acid (EDBA). The latter is formed by sequential metabolism of EMB by alcohol dehydrogenases (ADHs) and aldehyde dehydrogenases (ALDHs). The purpose of this study was to predict the levels of drug and EDBA in the eye using physiologically based pharmacokinetic (PBPK) modeling.

METHODS

The PBPK model of EMB was developed using GastroPlus. The intrinsic hepatic clearance of ALDH, calculated by the model, was scaled down using proteomics data to estimate the rate of formation of EDBA in the eye. Additionally, the comparative permeability of EMB and EDBA was assessed by employing in silico and in vitro approaches. The rate of formation of EDBA in the eye and permeability data were then incorporated in a compartmental model to predict the ocular levels of EMB and EDBA.

RESULTS

The simulation results of compartmental model highlighted that there was an on-site formation of EDBA upon metabolism of EMB. Furthermore, in silico and in vitro studies revealed that EDBA possessed much lower permeability than EMB. These observations meant that once EDBA was formed in the eye, it was not permeated out and hence achieved higher ocular concentration.

CONCLUSION

The on-site formation of EDBA in the eye, its higher local concentration due to lower ocular clearance and its pre-known characteristic to chelate metal species better explains the ocular toxicity shown by EMB.

Structural correlation to ferroelectric order, non-Griffiths like phase and magnetocaloric effect in YbCrO4

We report a ferroelectric order around ∼99 K (T_FE), which is considerably above the long range ferrimagnetic order at 25 K (T_N). The value of saturation electric polarization is considerable as ∼570μC m^-2for a poling field of 5 kV cm^-1. The ferroelectric order is associated with a significant magnetoelectric coupling below ∼90 K. A weak signature ofT_FEis observed in the dielectric constant, which is associated with a linear magnetodielectric response at 18 K(<TN). A transition to a polar structure has been correlated with the occurrence of ferroelectric order. A non-Griffiths like phase is observed around ∼48 K, which is also linked with the structural distortion. A reasonable value of the magnetic entropy change of 5.07 J Kg^-1 K^-1is noted atT_Nfor a change in field of 50 kOe, which involves a strong magnetoelastic coupling. The results indicate considerable structural instabilities, which is linked with the observed multifunctional properties of YbCrO₄.

180 NURSING HOMES DURING THE COVID-19 PANDEMIC: A NARRATIVE REVIEW OF CHALLENGES AND RESPONSES

Background

COVID-19 has caused unprecedented challenges in nursing homes. In this narrative review, we aimed to describe factors that contributed to the spread and mortality of COVID-19 in nursing homes and provide an overview of responses that were implemented to try to overcome such challenges.

Methods

The MeSH terms ‘Nursing homes’ and ‘COVID-19’ were searched in MEDLINE Ovid, and English language articles were retrieved that were published between 1 March 2020 and 31 January 2021. Article titles and abstracts were screened by two reviewers, and the results of included articles were grouped by themes.

Results

The search retrieved 348 articles, of which 76 were included in the thematic review. 8 articles related to COVID-19 disease characteristics (e.g. asymptomatic transmission), 24 to resident-related factors (e.g. comorbidities, nutrition, cognition), 13 to facility characteristics (e.g. physical space, occupancy, for-profit status), 21 to staffing (e.g. staffing levels, staff-to-resident ratio, staff multi-employment), and 10 to external factors (e.g. availability of personal protective equipment, prevailing health and social care policies). In terms of responses, identified themes included widespread testing, isolation and cohorting of residents, staff protection and support, promotion of residents’ well-being, and technological innovations.

Conclusion

COVID-19 exerted severe challenges on the nursing home population and its staff. Both internal and external factors predisposed nursing homes to an increased propensity of spread. Numerous strategies were employed to attempt to mitigate the negative impacts. Substantial learning occurred that may not only aid future pandemic preparedness but improve quality of care for nursing home residents at all times.

Use of personal protective equipment among waste workers of Sisdol landfill site of Nepal

Introduction: Solid waste management is a major issue in Nepal with Kathmandu valley generating the highest amount of solid waste. After recovery, the solid waste generated in Kathmandu valley is transferred to the Sisdol landfill site. There are waste workers in Sisdol landfill site who sustain their livelihood by collecting recyclables from those wastes. Personal protective equipment (PPE) is necessary to protect the frontline waste workers against infection. In addition, the waste workers need to know the proper usage of PPE in order to protect themselves from contamination. This study aimed to assess the awareness and proper usage of PPE along with the challenges faced by the waste workers at Sisdol landfill site. Methods: A descriptive cross-sectional study was conducted to collect data from landfill waste workers of Sisdol located at Kakani Rural Municipality in Nuwakot district of Nepal. A convenience sampling method was used based on the availability of landfill waste workers on that day and their willingness to participate. The data was collected using the structured questionnaire and personal interview of available waste workers. Results: The study comprised of 65% female and 35% male waste workers. The highest percentage of waste workers belong to 27-37 age group occupying 43% of total respondents.  Around 92% waste workers had participated in any orientation/training or session related to PPE and its usage. About 60% landfill waste workers were found only using mask and gloves. Conclusion: There is small number of waste workers who wish to wear full set of PPE. Most of them only like to wear mask and gloves. The gender, age group and the education level of waste workers had no association with the usage of PPE during the work.

Abstract 1266: Discovery and preclinical evaluation of a novel covalent inhibitor of FABP5 for cancer therapy

Dysregulated fatty acid metabolism is thought to be a hallmark of cancer, wherein fatty acids function both as an energy source and as signals for enzymatic and transcriptional networks contributing to malignancy. Fatty acid-binding protein 5 (FABP5) is an intracellular protein that facilitates transport of fatty acids and plays a role in regulating the expression of genes associated with cancer progression such as cell growth, survival, and metastasis. Overexpression of FABP5 has been reported to contribute to an aggressive phenotype and a poor survival correlation in several cancers. Therefore, inhibition of FABP5 is considered as a therapeutic approach for cancers. Phenotypic screening of a library of covalent compounds for selective sensitivity of cancer cells followed by medicinal chemistry optimization resulted in the identification of AUR104 with desirable properties. Chemoproteomic-based target deconvolution revealed FABP5 as the cellular target of AUR104. Covalent adduct formation with Cys43 of FABP5 by AUR104 was confirmed by mass spectrometry. Target occupancy studies using a biotin-tagged AUR104 demonstrated potent covalent binding to FABP5 in both cell-free and cellular conditions. Ligand displacement assay with a fluorescent fatty acid probe confirmed the competitive binding mode of AUR104 with fatty acids. Binding at the fatty acid site and covalent bond formation with Cys43 were also demonstrated by crystallography. Furthermore, AUR104 showed a high degree of selectivity against a broad safety pharmacology panel of enzymes and receptors. AUR104 exhibited potent anti-proliferative activity in a large panel of cell lines derived from both hematological and solid cancers with a high degree of selectivity over normal cells. Anti-proliferative activity in lymphoma cell lines correlated with inhibition of MALT1 pathway activity, cleavage of RelB/Bcl10 and secretion of cytokines, IL-10 and IL-6. AUR104 displayed desirable drug-like properties and dose-dependent oral exposure in pharmacokinetic studies. Oral dosing with AUR104 resulted in dose-dependent anti-tumor activity in DLBCL (OCI-LY10) and NSCLC (NCI-H1975) xenograft models. In a repeated dose MTD studies in rodents and non-rodents, AUR104 showed good tolerability with an exposure multiple of &gt;500 over cellular EC50 for up to 8 hours. In summary, we have identified a novel covalent FABP5 inhibitor with optimized properties that showed anti-tumor activity in in vitro and in vivo models with acceptable safety profile. The data presented here strongly support clinical development of AUR104.

Citation Format: Dinesh Chikkanna, Leena Khare Satyam, Sunil Kumar Pnaigrahi, Vinayak Khairnar, Manoj Pothuganti, Lakshmi Narayan Kaza, Narasimha Raju Kalidindi, Vijaya Shankar Nataraj, Aditya Kiran Gatta, Narasimha Rao Krishnamurthy, Sandeep Patil, DS Samiulla, Kiran Aithal, Vijay Kamal Ahuja, Nirbhay Kumar Tiwari, KB Charamannna, Pravin Pise, Thomas Anthony, Kavitha Nellore, Sanjeev Giri, Shekar Chelur, Susanta Samajdar, Murali Ramachandra. Discovery and preclinical evaluation of a novel covalent inhibitor of FABP5 for cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1266.

Abstract 1144: Orally bioavailable SMARCA2 degraders with exceptional selectivity and potency

Background: SMARCA2 (BRM) and SMARCA4 (BRG1) are two mutually exclusive DNA-dependent ATPases of the SWI/SNF complex, which function in mobilizing nucleosomes to regulate transcription, DNA replication/repair and chromosome dynamics. SMARCA4 is known to be mutated in number of cancers lacking targetable oncogenes, with SMARCA4-mutant patient population representing 10%-20% of NSCLC, 100% small cell ovarian cancer (hypercalcemic type), 28% skin cancer, 16% glioma and 14% colon cancer. Genetic studies have established the necessity of SMARCA2 for survival of tumor cells lacking SMARCA4. Although genetic silencing of SMARCA2 leads to potent anti-proliferative activity in SMARCA4-deficient cancer cell lines, pharmacological studies with a probe capable of binding to SMARCA2 and SMARCA4 bromodomains have failed to recapitulate such anti-proliferative effects. This prompted us to evaluate targeted protein degradation as an alternate approach to target SMARCA4 altered cancers.

Methods and Results: A variety of hetero bi-functional molecules were synthesized by conjugating selective SMARCA2/4 bromodomain inhibitors with either VHL or CRBN E3-ligase specific ligands. Rational design approach guided by our proprietary ternary complex modeling algorithm, ALMOND (ALgorithm for MOdeling Neosubstrate Degraders) resulted in the identification of highly selective SMARCA2 degraders. The lead compound, AU-19820 showed &gt; 10000-fold selectivity for SMARCA2 degradation versus other homologous proteins in tested cell lines. AU-19820 demonstrated potent anti-proliferative activity in SMARCA4 mutant but not in SMARCA2/4 proficient cell lines. This compound displayed favorable IV PK profile in rodents along with clean CYP profile. Additionally, the lead compound exhibited significant tumor growth inhibition in RERF-LC-A1 (SMARCA4 mutant lung cancer) xenograft model when dosed via i.v. route. Efficacious exposures were well tolerated with excellent tumor penetration. The compound also demonstrated moderate oral bioavailability in mouse. Efforts are in progress to improve this further by SAR modifications and exploiting prodrug approach.

Conclusions: Potent and extremely selective SMARCA2 protein degraders were identified by conjugating SMARCA2/4 inhibitors with known VHL or CRBN ligands. SMARCA2 vs SMARCA4 selectivity handles have been very well explored with expandable SAR. Lead compound also displayed a synthetic lethality phenotype in SMARCA4 mutant cancer models while sparing SMARCA2/4 proficient ones. Further optimization of the oral bioavailability and evaluation of efficacy through oral route as well as intermittent IV dosing are planned.

Citation Format: Chandrasekhar Abbineni, Leena Khare Satyam, Bilash Kuila, Ashok Ettam, Khaji Abdul Rawoof, Sreevidya MR, Sandeep Vitthal Dukare, Suraj T. Gore, Rakesh P. Nankar, Vijay Kamal Ahuja, Charamanna KB, Megha Goyal, Kiran Aithal, Samiulla DS, Subhendu Mukherjee, Thomas Antony, Sanjeev Giri, Shekar Chelur, Kavitha Nellore, Girish Daginakatte, Murali Ramachandra, Susanta Samajdar. Orally bioavailable SMARCA2 degraders with exceptional selectivity and potency [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1144.

Exploration of inhibition potential of isoniazid and its metabolites towards CYP2E1 in human liver microsomes through LC-MS/MS analysis

Isoniazid (INH) is the first-line anti-tubercular drug that is used both for the prophylaxis as well as the treatment of tuberculosis (TB). The patients with TB are more vulnerable to secondary infections and other health complications, hence, they are usually administered a cocktail of drugs. This increases the likelihood of drug-drug interactions (DDIs). INH is clinically proven to interact with drugs like phenytoin, carbamazepine, diazepam, triazolam, acetaminophen, etc. Most of such clinical observations have been supported by in vitro inhibition studies involving INH and cytochrome P450 (CYP) enzymes. A few published in vitro studies have explored the CYP2E1 inhibition potential of INH to explain its interactions with acetaminophen and other CY2E1 substrates, such as chlorzoxazone, but none of them were able to demonstrate any significant inhibition of the enzyme by the drug. It was reported that metabolites of INH, such as acetylhydrazine and hydrazine, were bioactivated by CYP2E1, highlighting that perhaps the drug metabolites were responsible for the mechanism based inhibition (MBI) of the enzyme. Therefore, the purpose of this investigation was to explore CYP2E1 enzyme inhibition potential of INH and its four major metabolites, viz., acetylisoniazid, isonicotinic acid, acetylhydrazine and hydrazine, using human liver microsomes (HLM). Additionally, we determined the fraction unbound in microsomal incubation (fu_mic) for all the five compounds using equilibrium dialysis assay. We observed that INH and its metabolites had lower propensity for microsomal binding, and the metabolites also lacked the potential to inhibit CYP2E1 enzyme, either by direct inhibition or through MBI. This suggests involvement of some other mechanism to explain interactions of INH with CY2E1 substrates, signifying need of further exploration.

Significant magneto-elastic coupling at Griffiths-like phase boundaries in low dimensional oxides,ASb2O6(ANi and Mn)

The compounds, NiSb₂O₆(NSO) and MnSb₂O₆(MSO) attract the community for the quasi one-dimensional and layered structure composed of Ni²⁺and Mn²⁺, which orders antiferromagnetically atT_N= 6.7 and 12 K, respectively. Here, we report the Griffiths-like phase much aboveT_Nin the range of 37-85 K and 25-80 K for NSO and MSO, respectively. The dc magnetization results indicate the Griffiths-like phase, following the modified Curie-Weiss law. The magneto-capacitive responses for both the compounds show anomalies at the onset of the Griffiths-like phase. Intriguingly, the low temperature synchrotron diffraction results are conclusive for determining the singularities for both the compounds. Interplay between the low-dimensionality, magnetic frustration, and magneto-elastic coupling correlates the observed short range ordered state, which is suggested as a Griffiths-like phase, aboveT_Nfor both the compounds.

Discovery of CA-4948, an Orally Bioavailable IRAK4 Inhibitor for Treatment of Hematologic Malignancies

Small molecule potent IRAK4 inhibitors from a novel bicyclic heterocycle class were designed and synthesized based on hits identified from Aurigene's compound library. The advanced lead compound, CA-4948, demonstrated good cellular activity in ABC DLBCL and AML cell lines. Inhibition of TLR signaling leading to decreased IL-6 levels was also observed in whole blood assays. CA-4948 demonstrated moderate to high selectivity in a panel of 329 kinases as well as exhibited desirable ADME and PK profiles including good oral bioavailability in mice, rat, and dog and showed >90% tumor growth inhibition in relevant tumor models with excellent correlation with in vivo PD modulation. CA-4948 was well tolerated in toxicity studies in both mouse and dog at efficacious exposure. The overall profile of CA-4948 prompted us to select it as a clinical candidate for evaluation in patients with relapsed or refractory hematologic malignancies including non-Hodgkin lymphoma and acute myeloid leukemia.

Discovery of CA-4948, an Orally Bioavailable IRAK4 Inhibitor for Treatment of Hematologic Malignancies

Small molecule potent IRAK4 inhibitors from a novel bicyclic heterocycle class were designed and synthesized based on hits identified from Aurigene's compound library. The advanced lead compound, CA-4948, demonstrated good cellular activity in ABC DLBCL and AML cell lines. Inhibition of TLR signaling leading to decreased IL-6 levels was also observed in whole blood assays. CA-4948 demonstrated moderate to high selectivity in a panel of 329 kinases as well as exhibited desirable ADME and PK profiles including good oral bioavailability in mice, rat, and dog and showed >90% tumor growth inhibition in relevant tumor models with excellent correlation with in vivo PD modulation. CA-4948 was well tolerated in toxicity studies in both mouse and dog at efficacious exposure. The overall profile of CA-4948 prompted us to select it as a clinical candidate for evaluation in patients with relapsed or refractory hematologic malignancies including non-Hodgkin lymphoma and acute myeloid leukemia.

Abstract 1754: First in class orally bioavailable BETBRD degraders

Background: Inhibition of Bromodomain and extra-terminal (BET) family proteins by small molecules is actively being pursued as a therapeutic strategy in the clinics. Targeted protein degradation is an emerging therapeutic modality that has shown initial promise in the clinic. BET protein degradation has inherent advantages over inhibition viz. expansion of indication scope and amenability to intermittent dosing schedules. While many BET degraders have been disclosed earlier, inferior pharmacokinetic properties limit their further development.

Methods and Results: We have designed and synthesized various hetero bi-functional molecules by conjugating novel and selective BET BRD ligands with VHL or CRBN ligands. This exercise led to the identification of several potent and selective BRD4 protein degraders with activity in a wide range of hematological and solid tumor cell lines. We have profiled one of the lead compounds extensively in vitro to gain insights on the mechanism of action. The lead compound showed lasting effect on BET protein abundance post compound washout while leading to apoptosis. This compound has favorable IV PK profile in rodents had has clean CYP and hERG profiles. Additionally, the lead compound exhibited significant tumor growth inhibition in MV4-11 xenograft model when dosed via i.v. route. Both QD and Q48h dosing regimens were well tolerated and produced efficacy in mouse models. Further SAR in the linker portion resulted in compounds with lower iv clearance and oral bioavailability either as prodrugs or as such. The proteomics study revealed a high selectivity towards BET proteins for the lead compound.

Conclusions: Potent and selective BET protein degraders were identified by conjugating novel BET BRD ligands with both VHL and CRBN ligands. Optimization of these first generation BET degraders led to improved metabolic stability, translating into low iv clearance in rodents. Further evaluation of these compounds as prodrugs resulted in good oral exposures. Lead compounds from both the series have low iv clearance and are orally bioavailable in a simple formulation. We believe these compounds serve as valuable tools to fully understand the clinical scope of BET degraders.

Citation Format: Chandrasekhar Abbineni, Mahaboobi Jaleel, Subhendu Mukherjee, Sivapriya Marappan, Nirbhay Kumar Tiwari, DS Samiulla, AB Aravind, Naveen R Kumar, Indu Bansal, Raghurami B Reddy, NVM Rao Bandaru, Akhila Srinivas, Janith Mary Maben, Suraj Tgore, Avainash Kumar, Rakesh P. Nankar, Chandranath D. Naik, Thomas Antony, Kavitha Nellore, Sanjeev Giri, Girish Daginakatte, Shekar Chelur, Olli Törmäkangas, Gerd Wohlfahrt, Mari Björkman, Elina Mattila, Laura Ravanti, Anu Moilanen, Murali Ramachandra, Susanta Samajdar. First in class orally bioavailable BETBRD degraders [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1754.

Abstract 1753: Targeting cancer with selective cbp/p300 bromodomain inhibitors

Background: The Bromodomain (BRD) and Extra-Terminal domain (BET) family of proteins are key regulators of epigenetic control. Although pan BET Inhibitors show good clinical activity, progressive disease was seen after several months of treatment in clinical responders, likely due to secondary resistance mechanisms. The plausible resistance mechanisms are increased expression of TCF7L2, c-Myc, Survivin and PIM1. Cyclic AMP response element binding protein (CREB)-binding protein (CBP) and E1A interacting protein of 300 kDa (EP300 or p300) are two closely related histone acetyl transferases with oncogenic roles in a variety of cancers. They are known to be co-activators of several key transcription factors that contribute to tumor progression including HIF1a, BRCA-1, p53, c-Myc and androgen receptor (AR). Studies have indicated that p300 is also upregulated in SPOP-mutated prostate cancer. Thus, targeting CBP/p300 represents an attractive approach for developing novel therapies.

Methods and Results: Multiple potent and selective CBP/p300 bromodomain inhibitors that are structurally unrelated to known inhibitors were identified by iterative medicinal chemistry and SAR based approaches. The compounds were optimized towards attaining good physicochemical properties and DMPK profile. The anti-proliferative activity of the lead compounds was studied across multiple tumor types in a 3-day assay. The lead compounds potently inhibited viability of a wide range of hematological and solid tumor cell lines including prostate cancer cell lines VCaP and 22Rv1. In H929 cell line the lead compounds showed dose-dependent inhibition of cMYC and increase in cPARP. In a single dose PK-PD study in MV4-11 xenograft model, the compounds showed modulation of cMYC and Survivin.

Conclusions: In summary, our studies demonstrate that selective CBP/p300 bromodomain inhibitors are potent in models of hematologic malignancies and solid tumors in-vitro. Profiling of efficacy in xenograft models, and further toxicological evaluation are in progress.

Citation Format: Mahaboobi Jaleel, Ramesh S. Senaiar, Chandrasekhar Abbineni, Girish A. Renukappa, Subhendu Mukherjee, Sivapriya Marappan, DS Samiulla, AB Aravind, Naveen R. Kumar, Venkata Siva N. Reddy, Asha Babu, Akhila P. Srinivas, Prasad Yadlapalli, Suraj Tgore, Raghavendra NR, Chandranath D. Naik, Sanjeev Giri, Thomas Antony, Kavitha Nellore, Shekar Chelur, Girish Daginakatte, laura Ravanti, Mikko Myllymäki, Gerd Wohlfahrt, Elina Mattila, Stefan Karlsson, Mari Björkman, Reetta Riikonen, Tarja Ikonen, Laura Leimu, Chira Mälmström, Timo Korjamo, Anu Moilanen, Murali Ramachandra, Susanta Samajdar. Targeting cancer with selective cbp/p300 bromodomain inhibitors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1753.

Interplay between positive magnetoresistance and thermoelectric properties by tuning carrier concentration in Sb2-xSnxTe3(x⩽ 0.05) crystals

We report transport properties of Sb2-xSnxTe3(x⩽ 0.05) single crystals, where the tuning of the charge carrier densities via Sn doping significantly improves the magnetoresistance (MR) and the thermoelectric (TE) properties. The MR increases significantly at 2 K forx= 0.01, which reduces considerably with further Sn doping atx= 0.05. The MR results below 90 K forx= 0.01 satisfy the semi-classical two-band approach of Kohler's rule, which does not satisfy the MR results forx= 0.05. At 300 K, the Seebeck coefficient (S) is positive and small forx= 0.01 and it changes the sign with the further increase in Sn doping atx= 0.05 at 300 K. The value of |S| is considerable with an enhancement of the thermoelectric power factor compared to the value forx= 0.01 at 300 K. Analysis of the Hall conductivity indicates the interplay between carrier mobilities and densities, leading to the tuning of MR and TE properties with Sn doping. These results demonstrate that the p-type Sb2Te3becomes n-type with a suitable doping engineering.

Insights into the degradation chemistry of tazarotene, a third generation acetylenic retinoid: LC-HRMS (Orbitrap), LC-MSn and NMR characterization of its degradation products, and prediction of their physicochemical and ADMET properties

Tazarotene is a prodrug that belongs to the acetylenic class of retinoids. The drug was subjected to hydrolytic, oxidative and photolytic stress testing to establish its comprehensive degradation chemistry. The drug proved to be unstable under acidic and basic hydrolytic conditions, yielding tazarotenic acid, which is a known major degradation product (DP) and an active metabolite. Additionally, two DPs each were generated upon interaction of drug and tazarotenic acid with HCl, used as an acid stressor. These were experimentally proven as pseudo DPs, as they did not originate when H₂SO₄ was employed as the stressor. The drug was also unstable under oxidative and photolytic conditions, yielding six DPs. All the products were separated on reversed phase (C18) column, using mobile phase composed of 10 mM ammonium formate (pH 3.5) and acetonitrile, which was run in a gradient mode. The separated DPs were subjected to LC-HRMS and LC-MSⁿ studies for their initial characterization. Seven hydrolytic and oxidative DPs that could be isolated using semi-preparative column were subjected to extensive 1D (¹H, ¹³C and DEPT-135) and 2D (COSY, HSQC and HMBC) NMR studies to confirm their structures. In total, five novel DPs were characterized, apart from two previously reported DPs, viz., tazarotenic acid and tazarotene sulfoxide, and four additional pseudo DPs. The complete degradation pathway of the drug was established. In silico ADMET properties of the drug and its DPs were evaluated using ADMET Predictor™.

In vitro evaluation of reactive nature of E- and Z-guggulsterones and their metabolites in human liver microsomes using UHPLC-Orbitrap mass spectrometer

Guggulipid is known to be useful for hypercholesterolemia, arthritis, acne, and obesity. These activities are attributed to its two principal isomeric active constituents, viz., E- and Z-guggulsterones. There are several side effects reported for guggulipid, which include widespread erythematous papules in a morbilliform pattern and macules localized to the arms; swelling and erythema of the face with burning sensation; pruritis; and bullous lesions on the lower legs with associated headaches, myalgia and itching. We hypothesized that one probable reason for these toxic reactions could be the formation of electrophilic reactive metabolites (RMs) of guggulsterones and their subsequent reaction with cellular proteins. Unfortunately, no report exists in the literature highlighting detection of RMs of guggulsterone isomers. Accordingly, the present study was undertaken to investigate the potential of E- and Z-guggulsterones to form RMs in human liver microsomes (HLM) using glutathione (GSH) and N-acetylcysteine (NAC) as trapping agents. The generated samples were analysed using ultra-high performance liquid chromatography (UHPLC) coupled to an Orbitrap mass spectrometer. The analysis of incubations with trapping agents highlighted that hydroxylated metabolites of guggulsterone isomers showed adduction with GSH and NAC. Even direct adducts of guggulsterone isomers were observed with both the trapping agents. The in silico toxicity potential of E- and Z-guggulsterones and their RMs was predicted using ADMET Predictor™ software and comparison was made against reported toxicities of guggulipid.

Characterization of Photodegradation Products of Bepotastine Besilate and In Silico Evaluation of Their Physicochemical, Absorption, Distribution, Metabolism, Excretion and Toxicity Properties

Bepotastine (BPT) is a H₁-receptor antagonist. It is used as a besilate salt in ophthalmic solution for allergic conjunctivitis and orally for the treatment of allergic rhinitis and urticaria/pruritus. Its systematic forced degradation study is unreported. The same was carried out in different conditions prescribed by International Conference on Harmonisation. The stressed solutions were subjected to reversed phase liquid chromatographic analysis, and BPT was observed to be labile under photobasic condition only, yielding 5 photodegradation products. The structures of the latter were elucidated from data generated by liquid chromatography-high-resolution mass spectrometry and multistage mass spectrometry. Of the 5, 4 products were further isolated and subjected to nuclear magnetic resonance spectroscopy to justify the proposed structures. Two of them, with similar accurate mass, were additionally and unambiguously characterized from their heteronuclear multiple bond correlation data, hydrogen deuterium exchange mass data, and quantum chemical analysis using density functional theory calculations. One degradation product had a structure that could only be explained by unusual rearrangement involving conversions of N-oxide into hydroxylamine, similar to Meisenheimer rearrangement. The physicochemical, as well as absorption, distribution, metabolism, excretion, and toxicity properties of BPT and its characterized photodegradation products were evaluated in silico by ADMET Predictor™ software.

Characterization of stable and reactive metabolites of piperine formed on incubation with human liver microsomes

Black pepper, though commonly employed as a spice, has many medicinal properties. It consists of volatile oils, alkaloids, pungent resins, etc., of which piperine is a major constituent. Though safe at low doses, piperine causes alteration in the activity of drug metabolising enzymes and transporters at high dose and is known to precipitate liver toxicity. It has a potential to form reactive metabolite(s) (RM) owing to the presence of structural alerts, such as methylenedioxyphenyl (MDP), α, β-unsaturated carbonyl group (Michael acceptor), and piperidine. The present study was designed to detect and characterize stable and RM(s) of piperine formed on in vitro incubation with human liver microsomes. The investigation of RMs was done with the aid of trapping agents, viz, glutathione (GSH) and N-acetylcysteine (NAC). The samples were analysed by ultra-high performance liquid chromatography coupled with high resolution mass spectrometry (UHPLC-HRMS) using Thermo Scientific Q Exactive Plus Orbitrap. Full scan MS followed by data-dependent MS² (Full MS-ddMS² ) mode was used to establish mass spectrometric fragmentation pathways of protonated piperine and its metabolites. In total, four stable metabolites and their isomers (M1a-c, M2a-b, M3a-c, and M4a-b) were detected. Their formation involved removal of carbon (3, M1a-c), hydroxylation (2, M2a-b), hydroxylation with hydrogenation (3, M3a-c), and dehydrogenation (2, M4a-b). Out of these metabolites, M1, M2, and M3 are reported earlier in the literature, but their isomers and two M4 variants are novel. In addition, six novel conjugates of RMs, including three GSH conjugates of m/z 579 and three NAC conjugates of m/z 435, were also observed.

Abstract 4418: Pharmacological characterization of a preclinical candidate covalently inhibiting CDK12

Cyclin-dependent kinase 12 (CDK12) is a transcription-associated protein that plays a critical role in DNA damage response, splicing, pre-mRNA processing and is crucial for maintaining genomic stability. CDK12 associated with Cyclin K (CycK) regulates transcription elongation by phosphorylating RNA polymerase II (RNAP II) at Serine 2 (pS2) in the C-terminal domain (CTD). Overexpression of CDK12 in various tumor types suggests the possibility that CDK12 has oncogenic properties, similarly to other transcription-associated kinases. Considering its critical role in transcription and RNA processing, CDK12 is emerging as a potential therapeutic target for cancer. Multiple series of potent and selective CDK12 covalent inhibitors were identified by structure-guided and iterative medicinal chemistry approaches. Early lead compounds were optimized towards achieving high on target potency with good selectivity and desirable drug like properties including pharmacokinetic profile to achieve anti-tumour activity. Optimization of early lead compounds from two distinct chemical series resulted in very potent and highly selective CDK12 covalent inhibitors with desirable oral bioavailability. The covalent mode of action for these biochemically potent compounds has been confirmed by CDK12 target engagement assay in the cellular context. These selective inhibitors showed significant anti-proliferative activity in TNBC and other cancer cell lines including those harbouring ETS fusion. Importantly, cell killing is observed in cancer cells but not in normal cells (RWPE1) with short time (2h) and long-time (72h) exposure of these compounds. Anti-proliferative activity is well correlated with the inhibition of pS2 and down-regulation of a number of DNA damage response genes including BRCA1, RAD51, ATM and FANCI. Consistent with the inhibition of genes involved in DNA damage repair, a highly synergistic anti-proliferative activity was observed when treated in combination with cisplatin and PARP inhibitors. Based on the robust efficacy as a single agent in a TNBC mouse xenograft model with one of the optimized leads, the preclinical candidate exhibiting a greater degree of selectivity is being evaluated for efficacy and tolerability in relevant preclinical models.

Citation Format: Ramulu Poddutoori, Sujatha Rajagopalan, Subhendu Mukherjee, Sivapriya Marappan, Samiulla D. S., Sasirekha Sivakumar, Shilpa S Nayak, Ravindra M V, Devaraja TS, Srinivas Kondela, Suraj Tgore, Amit A Dhudashiya, Charamanna K. B, Aravind A B, Amith A, Pavithra S, Hema Sankar Pathange, Thomas Antony, Mahaboobi Jaleel, Sanjeev Giri, Girish Daginakatte, Kavitha Nellore, Shekar Chelur, Murali Ramachandra, Susanta Samajdar. Pharmacological characterization of a preclinical candidate covalently inhibiting CDK12 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4418.

Unveiling spin-glass transition and antiferromagnetic order by μSR studies in spin-chain Sm2BaNiO5

We report the zero-field and longitudinal field muon spin relaxation studies in a spin-chain compound Sm₂BaNiO₅. Two magnetic transitions, that have not been previously detected by the heat capacity and magnetization measurements, are confirmed at 46 and 9 K. The antiferromagnetic order is suggested at 46 K. Analysis of the muon spin polarization unveils the spin-glass transition at 9 K. Time-field scaling relation of the muon spin polarization verifies the spin-spin autocorrelation function following the cut-off power law, which is approximated by the Ogielski form, as employed numerically for characterizing the spin-glasses.

Novel Bruton tyrosine kinase inhibitor acalabrutinib quantification by validated LC-MS/MS method: An application to pharmacokinetic study in Sprague Dawley rats

USFDA has approved a novel Bruton tyrosine kinase (BTK) inhibitor acalabrutinib (ACA) for the treatment of mantle cell lymphoma in adults. ACA is more potent and selective with fewer side effects compared to other Bruton tyrosine kinase inhibitors. In the current work a highly sensitive, selective and specific LC-MS/MS method for the estimation of acalabrutinib (ACA) in rat plasma was developed. Agilent Eclipse Plus C 8 column (50 mm × 4.6 mm, μm), with gradient elution using 10 mM ammonium formate and acetonitrile as mobile phase at a flow rate of 0.6 mL/min was used for the chromatographic separation. The ion transitions were quantified in positive mode with MRM transition of 466.1→372.3 for ACA and 236.8→194.0 for internal standard (IS). Solid phase extraction process was used as sample preparation approach. The method was validated according to USFDA bioanalytical guidelines. The method provided good linearity over the range of 0.2-199.14 ng/mL for ACA with short run time of 4 min. The method offers very high sensitivity (0.2 ng/mL) and was free from matrix interferences. The validated LC-MS/MS method was successfully applied for in vivo pharmacokinetic study in Sprague Dawley rats. The C_max of ACA was found to be 25.56 ng/mL reaching at time of 0.5 h. The developed analytical method can also be utilized for bioequivalence studies and/or for pharmacokinetic studies in clinics.

Abstract 2384: Preclinical evaluation of PD and efficacy of novel potent selective and orally bioavailable CDK12 covalent inhibitors in TNBC model

Cyclin-dependent kinase 12 (CDK12) is a transcription-associated kinase that participates in various cellular processes such as DNA damage response, splicing and pre-mRNA processing. In association with Cyclin K (CycK), CDK12 regulates transcription elongation by phosphorylating RNA polymerase II (RNAP II) at Serine 2 in the C-terminal domain (CTD). Overexpression of CDK12 in various tumor types suggests the possibility that CDK12 has oncogenic properties, similarly to other transcription-associated kinases. Considering its critical role in transcription and RNA processing CDK12 is emerging as a potential therapeutic target for cancer. Multiple series of potent and selective CDK12 covalent inhibitors were identified by iterative medicinal chemistry efforts and SAR-based approaches. Early compounds were optimized towards attaining good physicochemical properties, high potency, good selectivity and desirable pharmacokinetic profile to achieve anti-tumour activity. Very potent and highly selective CDK12 inhibitors have been identified from two distinct chemical series. The covalent mode of action for these biochemically potent compounds has been confirmed by CDK12 target engagement assay in the cellular context. These selective inhibitors showed significant anti-proliferative activity in TNBC and other cancer cell lines, which correlated with inhibition of pS2 (RNAP II), a bonafide CDK12 substrate and target engagement. In vivo target engagement, PD and efficacy data for optimized compounds with good oral bioavailability in a TNBC (HCC-70) xenograft model along with will be presented.

Citation Format: Ramulu Poddutoori, Sujatha Rajagopalan, Subhendu Mukherjee, Sivapriya Marappan, Samiulla D S, Sasirekha Sivakumar, Shilpa S. Nayak, Ravindra M. V, Hadianawala Murtuza, Devaraja T. S, Srinivas Kondela, Suraj Tgore, Amit A. Dhudashiya, Charamanna K. B, Thomas Antony, Girish Daginakatte, Sanjeev Giri, Shekar Chelur, Murali Ramachandra, Chetan Pandit, Susanta Samajdar. Preclinical evaluation of PD and efficacy of novel potent selective and orally bioavailable CDK12 covalent inhibitors in TNBC model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2384.