Distinct Mechanisms Of Action Research Articles

Harnessing the Therapeutic Potential of Antimicrobial peptides for cancers: State of the art.

Despite significant breakthroughs in cancer treatment, cancer remains a serious global health concern that takes thousands of lives each year. Still, drug resistance and adverse effects are the main problems in conventional cancer therapeutic approaches. Thus, the discovery of new anti-cancer agents with distinct mechanisms of action is a critical requirement that offers significant obstacles. Antimicrobial peptides (AMPs), which can be found in various forms of life, are recognized as defensive weapons against infections of microbial pathogens. Surprisingly, they are also capable of killing a variety of cancer cells. These powerful peptides can cause cell death in the gastrointestinal, urinary tract, and reproductive cancer cell lines. To emphasize the anti-cancer properties of AMPs, we summarize the research that examined their impact on cancer cell lines in this review.

Phase II study of biweekly TAS-102, irinotecan and bevacizumab in pre-treated metastatic colorectal cancer (TABAsCO).

3590 Background: The efficacy of 2nd line FOLFIRI plus VEGF inhibition (VEGFi) is limited for metastatic colorectal cancer (mCRC). TAS-102 is a novel oral anti-metabolite approved for pts with mCRC following standard treatment with FP, oxaliplatin and irinotecan. TAS-102 has a distinct mechanism of action from 5-FU and overcomes 5-FU resistance in preclinical models, and in the clinic. We hypothesized that the combination of TAS-102 with irinotecan (TAS-IRI) and bevacizumab (BEV) would prove superior to FOLFIRI/VEGFi. Methods: Phase II, single-arm study of TAS-IRI and BEV in 2nd-line mCRC. Eligible patients had received prior treatment with a fluoropyrimidine and oxaliplatin in the advanced setting or experienced recurrence within 12 mos of this regimen in the adjuvant setting. Adequate organ function, ECOG PS 0-1, measurable disease (RECIST 1.1), no prior irinotecan or TAS-102 exposure and candidacy for BEV were required. Pts were treated with BEV 5 mg/kg IV, irinotecan 180 mg/m2 IV (day 1 and 15), and TAS-102 25 mg/m2 orally bid (days 2-6 and 16-20) in 4-week cycles (PMID: 31924737). Treatment continued until disease progression or unacceptable toxicity. The primary endpoint was median progression-free survival (PFS). Assuming a median PFS for historic control (FOLFIRI/VEGFi) of 6 mos vs. 9 mos for TAS-IRI plus BEV (HR: 0.67), treatment of 36 evaluable pts would achieve 80.5% power (at α = 0.1) to detect such an effect. Results: Forty-nine patients were enrolled; 42 were eligible and 38 had at least one disease assessment (median age 59 yr, 47% male, 74% colon primary, tumor KRAS/NRAS mutated in 55%/21%). The median PFS was 8.7 mos (range: 6.7-11.8 mos, p = 0.009), meeting the primary endpoint. The most common reason for study treatment discontinuation was progressive disease (53%). The objective response rate was 16% (90% CI: 8.0-27.3%); the median OS was 16.5 mo (range: 11.8-25.3). Twenty-eight pts (67%) had a treatment-related adverse event (TRAE) G3 or higher (Table). The most common TRAEs were gastrointestinal and hematologic. Grade 3/4 neutropenia occurred in 34%, with only 1 episode of febile neutropenia, though G-CSF use was frequently needed to maintain dose density/intensity. Conclusions: TAS-IRI plus BEV is an effective 2nd line therapy for patients with mCRC. The median PFS appears higher compared to historical controls (FOLFIRI/VEGFi). Neutropenia is common and can affect dose density/intensity mandating use of G-CSF. A randomized study versus standard of care therapy is warranted. (Clinical trial registration ClinicalTrials.gov NCT04109924). Clinical trial information: NCT04109924 . [Table: see text]

Identifying the mechanistic differences between hypomethylating agents for the treatment of peripheral T cell lymphoma

Introduction: Peripheral T-cell lymphomas (PTCL) are a rare and heterogeneous group of malignancies that share a unifying feature of epigenetic dysregulation. Recent evidence suggests that PTCL, unlike other forms of cancer or even lymphoma, exhibits a marked vulnerability to hypomethylating agents (HMAs) alone and especially in combination with HDAC inhibitors. HMAs like azacitidine (AZA) and decitabine (DAC) have been shown to reverse transcriptional repression secondary to hypermethylation. Cladribine (CLAD) is FDA-approved for the treatment of hairy cell leukemia and is postulated to inhibit both DNA and histone methylation. Here, we sought to define the mechanistic differences between different DNA HMAs in order to inform a rationale on the optimal combinations that might exploit the epigenetic vulnerabilities of PTCL. Methods: Cell viability, caspase activity assay, and western blotting (WB) were performed on a panel of T-cell lymphoma cell lines to identify the effects of AZA/DAC/CLAD on cell survival, apoptosis, and DNA methyltransferase (DNMT) levels. Liquid chromatography-based mass spectrometry (LC-MS) was done to quantify 5-methyl cytosine (5-mC) levels. Results: Cell viability analysis confirmed that the dose and time-dependent sensitivity of the six PTCL cell lines differed following exposure to AZA/DAC/CLAD, where CLAD showed the lowest IC50 value (0.1–1 µM) across all cell lines, followed by AZA (IC50: 1–10 µM), and DAC had the least effect on cell viability (IC50: >100 µM, except T-ALL). A differential threshold of caspase activation was observed across the PTCL cell lines where CLAD showed the most superior caspase activity leading to the highest apoptotic potential. However, WB analysis showed that after 24 hours of treatment, DNMT1 and DNMT3A protein levels were significantly depleted at low concentrations of DAC (<0.01 µM) compared to AZA whereas CLAD did not affect the DNMT1 and DNMT3A levels. LC-MS-based quantification of 5-mC showed a similar relationship in methylation, with initial changes observed at doses >0.01 μM of DAC and >0.1 μM of AZA/CLAD. Taking the short half-life of AZA/DAC into account, cell viability assays with daily addition of AZA/DAC showed increased cell cytotoxicity for AZA/DAC treated samples, which was comparable to CLAD. Ongoing analyses of gene expression and metabolism of the universal methyl donor S-adenosylmethionine (SAM) will help to understand the mechanistic difference between these HMAs. Conclusions: These data suggest that the HMAs have a distinct mechanism of action for hypomethylation. While AZA/DAC induces hypomethylation by depletion of DNMTs, CLAD acts in a DNMT depletion-independent pathway. A mechanistic understanding of AZA/DAC/CLAD will inform how best to use them in clinic as well as assist in the strategic development of biological correlates to further support their therapeutic application. The research was funded by: Translational Orphan Blood Cancer Research Initiative Fund and RO1 # FD-R-006814-01. Keywords: Genomics, Epigenomics, and Other -Omics, Molecular Targeted Therapies No conflicts of interests pertinent to the abstract.

Ocular complications of antineoplastic therapies.

Ocular complications of antineoplastic agents can have a profound effect on the quality of life of cancer patients. New oncologic treatments like monoclonal antibodies, immunotherapies, antibody-drug conjugates, checkpoint inhibitors andgrowth factor receptorshave resulted in increased ocular complications. These ocular complications differs in respect to distinct mechanisms of actions and lead to significant challenges in the management of cancer patients. In this review, we reviewed literature, clinical studies and cases detailing ocular complications due to administration of antineoplastic agents and emphasized the need for communication between oncologists and ophthalmologists toward early detection and management of ocular complications.

Abstract ND01: ABBV-319: A first-in-class Glucocorticoid Receptor Modulator (GRM) agonist ADC for the treatment of B-cell malignancies

Abstract ABBV-319 is a novel CD19-targeting multi-modal antibody drug conjugate (ADC) for the treatment of B-cell malignancies. The ADC is engineered to have 3 distinct mechanisms of action to maximize anti-cancer activity while reducing systemic toxicities: (1) targeted GRM payload delivery, (2) signaling inhibition of CD19/BCR and (3) enhanced ADCC via afucosylation. Unlike traditional cytotoxic ADCs, the GRM payload is a high potency agonist (sub nM EC50) of the intracellular glucocorticoid receptor (GR) which then traffics to the nucleus resulting in sustained GR-driven transcriptional events leading to cancer cell death. CD19 is a clinically validated B-cell target (approved antibodies, ADCs, CARTs) known to be highly expressed even following multiple lines of therapy, making it an appropriate target for this novel approach. The CD19 antibody in ABBV-319 is an optimized high affinity IgG1 that can inhibit CD19/BCR downstream signaling events including AKT, leading to inhibition of growth in certain B-cell lines. Given ADCC/ADCP is a highly effective mechanism in B-cell malignancies (e.g., rituximab, tafasitamab) the CD19 antibody was engineered to have increased FcγR binding via afucosylation, that retains its enhanced ADCC activity as a GRM drug conjugate. By engineering the molecule in this way, the multi-modal ADC is not solely reliant on one mechanism of action for activity and therefore has the potential for broader activity. Sustained regressions/cures have been observed in multiple B-cell malignancy xenograft model systems (cell-line, PDX, humanized) after a single ADC dose that compares favorably against approved benchmark antibodies, systemic steroids and ADCs. ABBV-319 targets clinically validated mechanisms of action that are known to combine well with multiple standard-of-care agents. This combination potential together with its favorable safety profile, suggests ABBV-319 will be a highly effective combination treatment for B-cell malignancies. ABBV-319 was well tolerated in cynomolgus monkey studies with favorable drug-like properties and antibody-like pharmacokinetics, enabling a high mg/kg clinical starting dose. A first in-human Phase 1 clinical trial evaluating ABBV-319 in B-cell malignancies (DLBCL, FL, CLL) was recently initiated in late 2022 (clinicaltrials.gov, NCT05512390). Citation Format: James W. Purcell. ABBV-319: A first-in-class Glucocorticoid Receptor Modulator (GRM) agonist ADC for the treatment of B-cell malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr ND01.

The harmful acute effects of clomipramine in the rat liver: Impairments in mitochondrial bioenergetics

Clomipramine, a tricyclic antidepressant used to treat depression and obsessive-compulsive disorder, has been linked to a few cases of acute hepatotoxicity. It is also recognized as a compound that hinders the functioning of mitochondria. Hence, the effects of clomipramine on mitochondria should endanger processes that are somewhat connected to energy metabolism in the liver. For this reason, the primary aim of this study was to examine how the effects of clomipramine on mitochondrial functions manifest in the intact liver. For this purpose, we used the isolated perfused rat liver, but also isolated hepatocytes and isolated mitochondria as experimental systems. According to the findings, clomipramine harmed metabolic processes and the cellular structure of the liver, especially the membrane structure. The considerable decrease in oxygen consumption in perfused livers strongly suggested that the mechanism of clomipramine toxicity involves the disruption of mitochondrial functions. Coherently, it could be observed that clomipramine inhibited both gluconeogenesis and ureagenesis, two processes that rely on ATP production within the mitochondria. Half-maximal inhibitory concentrations for gluconeogenesis and ureagenesis ranged from 36.87 μM to 59.64 μM. The levels of ATP as well as the ATP/ADP and ATP/AMP ratios were reduced, but distinctly, between the livers of fasted and fed rats. The results obtained from experiments conducted on isolated hepatocytes and isolated mitochondria unambiguously confirmed previous propositions about the effects of clomipramine on mitochondrial functions. These findings revealed at least three distinct mechanisms of action, including uncoupling of oxidative phosphorylation, inhibition of the FoF1-ATP synthase complex, and inhibition of mitochondrial electron flow. The elevation in activity of cytosolic and mitochondrial enzymes detected in the effluent perfusate from perfused livers, coupled with the increase in aminotransferase release and trypan blue uptake observed in isolated hepatocytes, provided further evidence of the hepatotoxicity of clomipramine. It can be concluded that impaired mitochondrial bioenergetics and cellular damage are important factors underlying the hepatotoxicity of clomipramine and that taking excessive amounts of clomipramine can lead to several risks including decreased ATP production, severe hypoglycemia, and potentially fatal outcomes.

Insights into the mechanism of oligodendrocyte protection and remyelination enhancement by the integrated stress response.

central nervous system (CNS) inflammation triggers activation of the integrated stress response (ISR). We previously reported that prolonging the ISR protects remyelinating oligodendrocytes and promotes remyelination in the presence of inflammation. However, the exact mechanisms through which this occurs remain unknown. Here, we investigated whether the ISR modulator Sephin1 in combination with the oligodendrocyte differentiation enhancing reagent bazedoxifene (BZA) is able to accelerate remyelination under inflammation, and the underlying mechanisms mediating this pathway. We find that the combined treatment of Sephin1 and BZA is sufficient to accelerate early-stage remyelination in mice with ectopic IFN-γ expression in the CNS. IFN-γ, which is a critical inflammatory cytokine in multiple sclerosis (MS), inhibits oligodendrocyte precursor cell (OPC) differentiation in culture and triggers a mild ISR. Mechanistically, we further show that BZA promotes OPC differentiation in the presence of IFN-γ, while Sephin1 enhances the IFN-γ-induced ISR by reducing protein synthesis and increasing RNA stress granule formation in differentiating oligodendrocytes. Finally, pharmacological suppression of the ISR blocks stress granule formation in vitro and partially lessens the beneficial effect of Sephin1 on disease progression in a mouse model of MS, experimental autoimmune encephalitis (EAE). Overall, our findings uncover distinct mechanisms of action of BZA and Sephin1 on oligodendrocyte lineage cells under inflammatory stress, suggesting that a combination therapy may effectively promote restoring neuronal function in MS patients.

Discovery of novel covalent selective estrogen receptor degraders against endocrine-resistant breast cancer

Endocrine-resistance remains a major challenge in estrogen receptor α positive (ERα+) breast cancer (BC) treatment and constitutively active somatic mutations in ERα are a common mechanism. There is an urgent need to develop novel drugs with new mode of mechanism to fight endocrine-resistance. Given aberrant ERα activity, we herein report the identification of novel covalent selective estrogen receptor degraders (cSERDs) possessing the advantages of both covalent and degradation strategies. A highly potent cSERD 29c was identified with superior anti-proliferative activity than fulvestrant against a panel of ERα+ breast cancer cell lines including mutant ERα. Crystal structure of ERα‒29c complex alongside intact mass spectrometry revealed that 29c disrupted ERα protein homeostasis through covalent targeting C530 and strong hydrophobic interaction collied on H11, thus enforcing a unique antagonist conformation and driving the ERα degradation. These significant effects of the cSERD on ERα homeostasis, unlike typical ERα degraders that occur directly via long side chains perturbing the morphology of H12, demonstrating a distinct mechanism of action (MoA). In vivo, 29c showed potent antitumor activity in MCF-7 tumor xenograft models and low toxicity. This proof-of-principle study verifies that novel cSERDs offering new opportunities for the development of innovative therapies for endocrine-resistant BC.

Combining energy-based focal ablation and immune checkpoint inhibitors: preclinical research and clinical trials.

Energy-based focal therapy (FT) uses targeted, minimally invasive procedures to destroy tumors while preserving normal tissue and function. There is strong emerging interest in understanding how systemic immunity against the tumor can occur with cancer immunotherapy, most notably immune checkpoint inhibitors (ICI). The motivation for combining FT and ICI in cancer management relies on the synergy between the two different therapies: FT complements ICI by reducing tumor burden, increasing objective response rate, and reducing side effects of ICI; ICI supplements FT by reducing local recurrence, controlling distal metastases, and providing long-term protection. This combinatorial strategy has shown promising results in preclinical study (since 2004) and the clinical trials (since 2011). Understanding the synergy calls for understanding the physics and biology behind the two different therapies with distinctive mechanisms of action. In this review, we introduce different types of energy-based FT by covering the biophysics of tissue-energy interaction and present the immunomodulatory properties of FT. We discuss the basis of cancer immunotherapy with the emphasis on ICI. We examine the approaches researchers have been using and the results from both preclinical models and clinical trials from our exhaustive literature research. Finally, the challenges of the combinatory strategy and opportunities of future research is discussed extensively.

Immune Dysfunction in Medication-Related Osteonecrosis of the Jaw.

The pathogenesis of medication-related osteonecrosis of the jaw (MRONJ) is multifactorial and there is a substantial consensus on the role of antiresorptive drugs (ARDs), including bisphosphonates (BPs) and denosumab (Dmab), as one of the main determinants. The time exposure, cumulative dose and administration intensity of these drugs are critical parameters to be considered in the treatment of patients, as cancer patients show the highest incidence of MRONJ. BPs and Dmab have distinct mechanisms of action on bone, but they also exert different effects on immune subsets which interact with bone cells, thus contributing to the onset of MRONJ. Here, we summarized the main effects of ARDs on the different immune cell subsets, which consequently affect bone cells, particularly osteoclasts and osteoblasts. Data from animal models and MRONJ patients showed a deep interference of ARDs in modulating immune cells, even though a large part of the literature concerns the effects of BPs and there is a lack of data on Dmab, demonstrating the need to further studies.

Mechanisms of Action of the Host-Targeting Agent Cyclosporin A and Direct-Acting Antiviral Agents against Hepatitis C Virus.

Several direct-acting antivirals (DAAs) are available, providing interferon-free strategies for a hepatitis C cure. In contrast to DAAs, host-targeting agents (HTAs) interfere with host cellular factors that are essential in the viral replication cycle; as host genes, they are less likely to rapidly mutate under drug pressure, thus potentially exhibiting a high barrier to resistance, in addition to distinct mechanisms of action. We compared the effects of cyclosporin A (CsA), a HTA that targets cyclophilin A (CypA), to DAAs, including inhibitors of nonstructural protein 5A (NS5A), NS3/4A, and NS5B, in Huh7.5.1 cells. Our data show that CsA suppressed HCV infection as rapidly as the fastest-acting DAAs. CsA and inhibitors of NS5A and NS3/4A, but not of NS5B, suppressed the production and release of infectious HCV particles. Intriguingly, while CsA rapidly suppressed infectious extracellular virus levels, it had no significant effect on the intracellular infectious virus, suggesting that, unlike the DAAs tested here, it may block a post-assembly step in the viral replication cycle. Hence, our findings shed light on the biological processes involved in HCV replication and the role of CypA.

Abstract LB071: A phenomics platform combining imaging and artificial intelligence for rapid validation and advancement of novel oncology targets

Abstract The emergence of technological innovations has created the opportunity to envision new approaches to discover therapeutics at scale. We combined advances in high content microscopy with arrayed CRISPR genome editing techniques and machine learning (ML) to build a rigorously controlled dataset enabling exploration of biology and chemistry at scale. Phenotypes from millions of perturbations in multiple cell types were embedded in a unified representation space and leveraged to accelerate discovery and reverse translation, ultimately yielding novel biological insights, and optimizing the advancement of lead molecular series through structure-activity relationships (SAR). Here, we demonstrate the capability of our platform to discover potential cancer therapies with distinct mechanisms of action. First, we describe the identification of a novel compound series that potentiates the effects of immunotherapy in syngeneic mouse models, producing complete responses and immunological memory, while also limiting peripheral inflammation. Specific novel chemical entities (NCEs) caused robust CD45+ cell influx into the tumor microenvironment and significantly attenuated exhausted T cells and immunosuppressive macrophages, thereby enhancing anti-tumor immunity. Strikingly, the same NCEs suppressed peripheral inflammation while sustaining elevated levels of intra-tumoral proinflammatory cytokines. Second, we highlight a novel and differentiated strategy to potentiate PARP inhibitor response in homologous repair deficient (HRD) - negative or HR-proficient ovarian cancers. NCEs altered the expression of genes within the DNA damage repair (DDR) network and cell cycle checkpoints to synergize with PARP inhibition in vivo and re-sensitized a PARP-resistant patient-derived xenograft (PDX) model. Collectively, we believe future efforts on the industrialization and integration of various technological innovations across biology, chemistry, automation, data science, and engineering will ultimately modernize drug discovery and radically improve patient lives. Citation Format: Jenny Rudnick, Kiran Nadella, Chase Neumann, Shane Rowley, Ethan Gardner, Shadi Swaidani, Aimee Iberg, Lu Chen, Daria Beshnova, Aurora Blucher, Rebecca Sarto Basso, Malini Rajan, Kevin Fales, Ashraf Saeed, Christopher Bailey, Weston Judd, Chrissy Egbert, Joel Ellis, John Ansede, Pouya Hadipour, Kevin Jessing, Janet Paulsen, Paul Rearden, Vamshi Manda, Sashi Kasimsetty, Sashi Kasimsetty, Michael Hancock, Harish Shankaran, Bryan Ellis, Meenakshy Iyer, Carl Brooks, Ashish Bhandari, Chris Gibson, Irit Rappley, Laura Schaevitz, Imran Haque, Hayley Donnella, Michael Cuccarese, Marie Evangelista. A phenomics platform combining imaging and artificial intelligence for rapid validation and advancement of novel oncology targets [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB071.

Abstract 6308: Preclinical development of ABBV-319: a CD19-targeting glucocorticoid receptor modulator (GRM) agonist antibody-drug conjugate (ADC) for the treatment of B-cell malignancies

Abstract Introduction: Glucocorticoids are key components of standard-of-care treatment regimens (e.g., R-CHOP, Hyper-CVAD) for several B-cell malignancies. However, prolonged systemic glucocorticoid treatment results in glucocorticoid-associated adverse events and acquired resistance that limit its therapeutic potential. ABBV-319 is a novel CD19-targeting ADC engineered to reduce glucocorticoid-associated toxicity observed with systemic glucocorticoids while possessing three distinct mechanisms of action (MoA) to increase efficacy: 1) antibody-mediated delivery of GRM to activate glucocorticoid receptor (GR) induced cell death in cancer cells, 2) inhibition of CD19 signaling, and 3) enhanced Fc-mediated cancer cell killing via afucosylation of the antibody backbone. Results: We identified a GRM agonist that is 15 and 150 times more potent at driving GR transcriptional activation and cell death compared to clinical glucocorticoids dexamethasone and prednisolone, respectively. The conjugation of GRM agonist as the payload on ABBV-319 enables potent GRM-driven anti-cancer activity against malignant B-cell lines in vitro as well as in cell-line and patient derived xenograft (CDX and PDX) models in vivo. Remarkably, a single-dose of ABBV-319 induced sustained tumor regression and enhanced anti-tumor activity compared to repeat dosing of systemic glucocorticoids (e.g., prednisolone) at its maximum tolerated dose in mice. The CD19 monoclonal antibody (mAb) also reduced proliferation of a subset of B-cell malignant cell lines through inhibition of the PI3K/AKT pathway. Moreover, afucosylation of the CD19 mAb in ABBV-319 enhanced Fc-mediated antibody-dependent cellular cytotoxicity (ADCC), and this activity was maintained after conjugation with GRM payloads. ABBV-319 bound similarly to both V158 (high-affinity) and F158 (low-affinity) FcγRIIIa allotypes and mediated potent ADCC in co-culture assays with human peripheral blood mononuclear cells (PBMCs). Notably, ABBV-319 displayed superior efficacy compared to afucosylated CD19 mAb in human CD34+ hematopoietic stem cell-engrafted NSG-Tg(Hu-IL15) mice, demonstrating that the three MoA (GR-driven cell death, CD19 signaling inhibition, and ADCC) collectively contribute to anti-tumor activity in vivo. ABBV-319 also displayed on-target depletion of normal human B-cells but did not affect peripheral NK cell counts in mice. Furthermore, CITE-seq profiling revealed that ABBV-319 treatment of human PBMCs activated GRM-induced signature genes restricted to B-cells, demonstrating the specificity of CD19-mediated delivery of GRM. Conclusion: ABBV-319 has potent anti-tumor activity from three distinct MoA and exhibits safety improvements compared to systemic glucocorticoids, supporting its recent progression into Phase I clinical trial. Citation Format: Chewei Anderson Chang, Ethan Emberley, Aloma L. D'Souza, Weilong Zhao, Cormac Cosgrove, Axel Hernandez Jr, Anatol Oleksijew, Paul Ellis, Luis Rodriguez, Gail Bukofzer, David Peetz, Wissam Assaily, Raghuveer Singh Mali, Wei Liu, Danqing Xu, Gregory K. Potts, Shaun McLoughlin, Kimberley McCarthy, Zhaomei Zhang, Jos Campbell, Isabella Sturdevant, Gloria Zhang, Tyler Curran, Jon D. Williams, Erwin Boghaert, Milan Bruncko, Christopher C. Marvin, Adrian Hobson, Michael Mcpherson, Tamar Uziel, Marybeth Pysz, Xi Zhao, Alex Bankovich, Kevin J. Freise, Susan Morgan-Lappe, James W. Purcell. Preclinical development of ABBV-319: a CD19-targeting glucocorticoid receptor modulator (GRM) agonist antibody-drug conjugate (ADC) for the treatment of B-cell malignancies. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6308.

Abstract 6406: Radiation and STING activation limit tumor development and modulate the immune environment via distinct mechanisms

Abstract Carcinogen-induced lung cancer in A/J mice is an established model of tumor initiation and development. The impact of radiation, immune response, and STING pathway activation on tumor development in this model is not well understood. In this study, we examined the effect of radiation and the STING agonist, DMXAA (Vadimezan), on the development of urethane-induced lung cancer. A/J mice were treated with urethane (i.p.) to induce the development of lung tumors. Three days after urethane treatment, mice received 13 Gy thorax radiation treatment (RT)/mock RT, DMXAA (20 mg/kg i.p.)/vehicle, or a combination treatment (n = 5). Mice were euthanized after 6 hours to 7 days after treatment to assess early events in the lung with RNA-sequencing and flow cytometry, or 5 months after treatment to assess tumor growth and long-term changes to the immune microenvironment with multiplex immunofluorescence. Mice treated with urethane followed by RT had fewer lung surface tumors (p &amp;lt; 0.01) and reduced tumor area (p = 0.0732) compared to their mock RT controls. In parallel, mice that received urethane pre-treatment and RT had high numbers of tertiary lymphoid structures (TLSs; these contained T-cells, B-cells, MHCII+ APCs and CXCL13) compared to the mock RT control mice (p &amp;lt; 0.001). Analysis of immune cell contents of the TLS revealed a notable increase in CD4, CD8 and regulatory T-cells in the RT condition (with urethane pretreatment). Important early events in the lung following RT of urethane pre-treated mice included a transient increase in type I and type II interferons, CD4 and CD8 T-cell infiltration (p &amp;lt; 0.001) and a strong downregulation of cell cycle events. In contrast to these findings, DMXAA treatment after urethane resulted in fewer tumors (p &amp;lt; 0.05), but larger tumors compared to the vehicle-treated group. An increase in immune cells was observed in the lung, however, without clear structures that resembled TLSs. Early events following DMXAA treatment with urethane pre-treatment included dampened levels of type I IFN and TNF-α in circulation and a decrease in T-cell infiltration into the lungs. Interestingly, RT and DMXAA combination treatment (with urethane pre-treatment) drove a synergistic anti-tumor effect, further reducing tumor numbers compared to the RT or DMXAA controls 5 months after treatment. RT and STING agonist treatment of pre-neoplastic lesions have differential impacts on tumor growth in the A/J mouse model, and work synergistically when combined. The different outcomes of RT and DMXAA on tumor growth may be driven by their distinctive mechanism of action on immune responses and capacities to form TLSs. These findings may have future implications for strategies for the early treatment of lung and other cancers, and they suggest that immune responses, including modulation of the STING pathway, may be an important aspect of early tumor development that could be targeted therapeutically. Citation Format: Kay Shigemori, Yanyan Jiang, Bruno Beernaert, Anderson J. Ryan, Eileen E. Parkes. Radiation and STING activation limit tumor development and modulate the immune environment via distinct mechanisms [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6406.

Abstract 395: Resistance to tyrosine kinase inhibitor confers an immunosuppressive microenvironment and cross-resistance to immunotherapy through AXL/PDPK1 axis in liver cancer

Abstract Systemic therapy is the current standard of care for unresectable advanced hepatocellular carcinoma (HCC), the most malignant form of liver cancer. Clinical practice guideline for HCC includes the management of the second-line immunotherapies after patients become unresponsive to first-line targeted therapies using tyrosine kinase inhibitors (TKI), which is expected to generate optimal therapeutic effect due to the distinct mechanism of action between TKIs and immunotherapies. However, evidence from clinical trials suggests that the response to immunotherapy following TKI treatment is often compromised in TKI-resistant HCC as compared with treatment-naïve HCC, indicating a potential cross-resistance to immunotherapy, which impedes the optimal therapeutic effect of the second-line immunotherapies. In the present study, we first explored the therapeutic effect of anti-PD-1 immunotherapy in TKI-resistant HCC and successfully validated the putative cross-resistance to immunotherapy after TKI treatment. We further observed that TKI-resistant HCC exhibits an immune-evasive microenvironment, characterized by decreased CD8+ T cell and dendritic cell infiltration. This is potentially caused by the intratumoral activation of receptor tyrosine kinase AXL and its downstream target PDPK1 which protect TKI-resistant HCC cells from mitochondrial oxidative stress and the cytosolic leakage of mitochondrial DNA, which subsequently suppresses cGAS-STING together with its downstream interferon pathways and immunogenic cell death. Genetic manipulation of AXL and PDPK1 in TKI-resistant HCC cells abrogated the protective effect and thus activated the immunogenic responses. Blockade of AXL with a selective inhibitor BGB324 re-sensitized TKI-resistant HCC to anti-PD-1 treatment. The current findings suggest that targeting AXL/PDPK1 signaling axis might overcome cross-resistance to second-line immunotherapy for HCC patients who progress on TKI treatment. Citation Format: Yunong Xie, Bosheng Huang, Huajian Yu, Jia-Jian Loh, Rainbow Wing-Hei Leung, Terence Lee, Stephanie Ma, Man Tong. Resistance to tyrosine kinase inhibitor confers an immunosuppressive microenvironment and cross-resistance to immunotherapy through AXL/PDPK1 axis in liver cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 395.

MarR-Dependent Transcriptional Regulation of mmpSL5 Induces Ethionamide Resistance in Mycobacterium abscessus.

Mycobacterium abscessus (Mabs) is an emerging nontuberculosis mycobacterial (NTM) pathogen responsible for a wide variety of respiratory and cutaneous infections that are difficult to treat with standard antibacterial therapy. Mabs has a high degree of both innate and acquired antibiotic resistance to most clinically relevant drugs, including standard anti-mycobacterial agents. Ethionamide (ETH), an inhibitor of mycolic acid biosynthesis, is currently utilized as a second-line agent for treating multidrug-resistant tuberculosis infections. Here, we show that ETH displays activity against clinical strains of Mabs in vitro at concentrations that are >100× lower than other mycolic acid targeting drugs. Using transposon mutagenesis followed by transposon sequencing (Tn-Seq) and whole-genome sequencing of spontaneous ETH-resistant mutants, we identified MAB_2648c as a genetic determinant of ETH sensitivity in Mabs. MAB_2648c encodes a MarR family transcriptional regulator of the TetR class of regulators. We show that MAB_2648c represses expression of MAB_2649 (mmpS5) and MAB_2650 (mmpL5). Further, we show that derepression of these genes in MAB_2648c mutants confers resistance to ETH, but not other antibiotics. To identify determinants of resistance that may be shared across antibiotics with distinct mechanisms of action, we also performed Tn-Seq during treatment with amikacin and clarithromycin, drugs currently used clinically to treat Mabs. We found very little overlap in genes that modulate the sensitivity of Mabs to all three antibiotics, suggesting a high degree of specificity for resistance mechanisms in this emerging pathogen.

Triphenyltin(IV) Carboxylates with Exceptionally High Cytotoxicity against Different Breast Cancer Cell Lines.

Organotin(IV) carboxylates are a class of compounds explored as alternatives to platinum-containing chemotherapeutics due to propitious in vitro and in vivo results, and distinct mechanisms of action. In this study, triphenyltin(IV) derivatives of non-steroidal anti-inflammatory drugs (indomethacin (HIND) and flurbiprofen (HFBP)) are synthesized and characterized, namely [Ph3Sn(IND)] and [Ph3Sn(FBP)]. The crystal structure of [Ph3Sn(IND)] reveals penta-coordination of the central tin atom with almost perfect trigonal bipyramidal geometry with phenyl groups in the equatorial positions and two axially located oxygen atoms belonging to two distinct carboxylato (IND) ligands leading to formation of a coordination polymer with bridging carboxylato ligands. Employing MTT and CV probes, the antiproliferative effects of both organotin(IV) complexes, indomethacin, and flurbiprofen were evaluated on different breast carcinoma cells (BT-474, MDA-MB-468, MCF-7 and HCC1937). [Ph3Sn(IND)] and [Ph3Sn(FBP)], unlike the inactive ligand precursors, were found extremely active towards all examined cell lines, demonstrating IC50 concentrations in the range of 0.076-0.200 µM. Flow cytometry was employed to examine the mode of action showing that neither apoptotic nor autophagic mechanisms were triggered within the first 48 h of treatment. However, both tin(IV) complexes inhibited cell proliferation potentially related to the dramatic reduction in NO production, resulting from downregulation of nitric oxide synthase (iNOS) enzyme expression.

Analytical Method Development and Validation for the Simultaneous Estimation of Olmesartan and Hydrochlorothiazide by RP-HPLC in Bulk and Tablet Dosage Forms

New medication combinations are introduced every day. As a result, various diseases and disorders are treated using a combination of several therapeutic medicines that each have a somewhat distinct mechanism of action. Therefore, it is crucial to develop methods of analyzing medicines employing a range of methods that may be utilized. A UV 730d (dad) absorbance detector, a 20 L injection loop, a sp 930d pump, a 4.6 by 100 mL C18 column (Agilent), and Chemstation software are all included in the setup: approximately 60 water and 40% methanol (pH 3.0 adjust with OPA). Maximum effi ciency was achieved when the system was operated at a wavelength of 233 nm. The procedure’s effi cacy was confi rmed by testing it against ICH guidelines. These techniques were found to be linear, precise, broad, and stable. The procedure was found to be easy, accurate, exact, aff ordable, and easy to use again and again. This means that olmesartan and hydrochlorothiazide, in both bulk form and fi nished products, can be tested for quality using the proposed methodologies.

Viral target and metabolism-based rationale for combined use of recently authorized small molecule COVID-19 medicines: Molnupiravir, nirmatrelvir, and remdesivir.

The COVID-19 pandemic remains a major health concern worldwide, and SARS-CoV-2 is continuously evolving. There is an urgent need to identify new antiviral drugs and develop novel therapeutic strategies. Combined use of newly authorized COVID-19 medicines including molnupiravir, nirmatrelvir, and remdesivir has been actively pursued. Mechanistically, nirmatrelvir inhibits SARS-CoV-2 replication by targeting the viral main protease (Mpro ), a critical enzyme in the processing of the immediately translated coronavirus polyproteins for viral replication. Molnupiravir and remdesivir, on the other hand, inhibit SARS-CoV-2 replication by targeting RNA-dependent RNA-polymerase (RdRp), which is directly responsible for genome replication and production of subgenomic RNAs. Molnupiravir targets RdRp and induces severe viral RNA mutations (genome), commonly referred to as error catastrophe. Remdesivir, in contrast, targets RdRp and causes chain termination and arrests RNA synthesis of the viral genome. In addition, all three medicines undergo extensive metabolism with strong therapeutic significance. Molnupiravir is hydrolytically activated by carboxylesterase-2 (CES2), nirmatrelvir is inactivated by cytochrome P450-based oxidation (e.g., CYP3A4), and remdesivir is hydrolytically activated by CES1 but covalently inhibits CES2. Additionally, remdesivir and nirmatrelvir are oxidized by the same CYP enzymes. The distinct mechanisms of action provide strong rationale for their combined use. On the other hand, these drugs undergo extensive metabolism that determines their therapeutic potential. This review discusses how metabolism pathways and enzymes involved should be carefully considered during their combined use for therapeutic synergy.

An anti-HER2 biparatopic antibody that induces unique HER2 clustering and complement-dependent cytotoxicity

Human epidermal growth factor receptor 2 (HER2) is a receptor tyrosine kinase that plays an oncogenic role in breast, gastric and other solid tumors. However, anti-HER2 therapies are only currently approved for the treatment of breast and gastric/gastric esophageal junction cancers and treatment resistance remains a problem. Here, we engineer an anti-HER2 IgG1 bispecific, biparatopic antibody (Ab), zanidatamab, with unique and enhanced functionalities compared to both trastuzumab and the combination of trastuzumab plus pertuzumab (tras + pert). Zanidatamab binds adjacent HER2 molecules in trans and initiates distinct HER2 reorganization, as shown by polarized cell surface HER2 caps and large HER2 clusters, not observed with trastuzumab or tras + pert. Moreover, zanidatamab, but not trastuzumab nor tras + pert, elicit potent complement-dependent cytotoxicity (CDC) against high HER2-expressing tumor cells in vitro. Zanidatamab also mediates HER2 internalization and downregulation, inhibition of both cell signaling and tumor growth, antibody-dependent cellular cytotoxicity (ADCC) and phagocytosis (ADCP), and also shows superior in vivo antitumor activity compared to tras + pert in a HER2-expressing xenograft model. Collectively, we show that zanidatamab has multiple and distinct mechanisms of action derived from the structural effects of biparatopic HER2 engagement.