SGN-B7H4V, an investigational vedotin ADC directed to the immune checkpoint ligand B7-H4, shows promising activity in preclinical models.

BACKGROUND: SGN-B7H4V is a novel investigational vedotin antibody-drug conjugate (ADC) comprising a B7-H4-directed human monoclonal antibody conjugated to the cytotoxic payload monomethyl auristatin E (MMAE) via a protease-cleavable maleimidocaproyl valine citrulline (mc-vc) linker. This vedotin linker-payload system has been clinically validated in multiple Food and Drug Administration approved agents including brentuximab vedotin, enfortumab vedotin, and tisotumab vedotin. B7-H4 is an immune checkpoint ligand with elevated expression on a variety of solid tumors, including breast, ovarian, and endometrial tumors, and limited normal tissue expression. SGN-B7H4V is designed to induce direct cytotoxicity against target cells by binding to B7-H4 on the surface of target cells and releasing the cytotoxic payload MMAE upon internalization of the B7-H4/ADC complex. METHODS: B7-H4 expression was characterized by immunohistochemistry across multiple solid tumor types. The ability of SGN-B7H4V to kill B7-H4-expressing tumor cells in vitro and in vivo in a variety of xenograft tumor models was also evaluated. Finally, the antitumor activity of SGN-B7H4V as monotherapy and in combination with an anti-programmed cell death-1 (PD-1) agent was evaluated using an immunocompetent murine B7-H4-expressing Renca tumor model. RESULTS: Immunohistochemistry confirmed B7-H4 expression across multiple solid tumors, with the highest prevalence in breast, endometrial, and ovarian tumors. In vitro, SGN-B7H4V killed B7-H4-expressing tumor cells by MMAE-mediated direct cytotoxicity and antibody-mediated effector functions including antibody-dependent cellular cytotoxicity and antibody-dependent cellular phagocytosis. In vivo, SGN-B7H4V demonstrated strong antitumor activity in multiple xenograft models of breast and ovarian cancer, including xenograft tumors with heterogeneous B7-H4 expression, consistent with the ability of vedotin ADCs to elicit a bystander effect. In an immunocompetent murine B7-H4-expressing tumor model, SGN-B7H4V drove robust antitumor activity as a monotherapy that was enhanced when combined with an anti-PD-1 agent. CONCLUSION: The immune checkpoint ligand B7-H4 is a promising molecular target expressed by multiple solid tumors. SGN-B7H4V demonstrates robust antitumor activity in preclinical models through multiple potential mechanisms. Altogether, these preclinical data support the evaluation of SGN-B7H4V as a monotherapy in the ongoing phase 1 study of SGN-B7H4V in advanced solid tumors (NCT05194072) and potential future clinical combinations with immunotherapies.

Dynamics of antioxidant heme oxygenase-1 and pro-oxidant p66Shc in promoting advanced prostate cancer progression.

The castration-resistant (CR) prostate cancer (PCa) is lethal and is the second leading cause of cancer-related deaths in U.S. males. To develop effective treatments toward CR PCa, we investigated reactive oxygen species (ROS) signaling pathway for its role involving in CR PCa progression. ROS can regulate both cell growth and apoptosis: a moderate increase of ROS promotes proliferation; its substantial rise results in cell death. p66Shc protein can increase oxidant species production and its elevated level is associated with the androgen-independent (AI) phenotype of CR PCa cells; while heme oxygenase-1 (HO-1) is an antioxidant enzyme and elevated in a sub-group of metastatic PCa cells. In this study, our data revealed that HO-1 and p66Shc protein levels are co-elevated in various AI PCa cell lines as well as p66Shc cDNA-transfected cells. Knockdown and/or inhibition of either p66Shc or HO-1 protein leads to reduced tumorigenicity as well as a reduction of counterpart protein. Knockdown of HO-1 alone results in increased ROS levels, nucleotide and protein oxidation and induction of cell death. Together, our data indicate that elevated HO-1 protein levels protect PCa cells from otherwise apoptotic conditions induced by aberrant p66Shc/ROS production, which thereby promotes PCa progression to the CR phenotype. p66Shc and HO-1 can serve as functional targets for treating CR PCa.

A digital assay for programmed death-ligand 1 (22C3) quantification combined with immune cell recognition algorithms in non-small cell lung cancer.

PD-L1 (22C3) checkpoint inhibitor therapy represents a mainstay of modern cancer immunotherapy for non-small cell lung cancer (NSCLC). In vitro diagnostic (IVD) PD-L1 antibody staining is widely used to predict clinical intervention efficacy. However, pathologist interpretation of this assay is cumbersome and variable, resulting in poor positive predictive value concerning patient therapy response. To address this, we developed a digital assay (DA) termed Tissue Insight (TI) 22C3 NSCLC, for the quantification of PD-L1 in NSCLC tissues, including digital recognition of macrophages and lymphocytes. We completed clinical validation of this digital image analysis solution in 66 NSCLC patient samples, followed by concordance studies (comparison of PD-L1 manual and digital scores) in an additional 99 patient samples. We then combined this DA with three distinct immune cell recognition algorithms for detecting tissue macrophages, alveolar macrophages, and lymphocytes to aid in sample interpretation. Our PD-L1 (22C3) DA was successfully validated and had a scoring agreement (digital to manual) higher than the inter-pathologist scoring. Furthermore, the number of algorithm-identified immune cells showed significant correlation when compared with those identified by immunohistochemistry in serial sections stained by double immunofluorescence. Here, we demonstrated that TI 22C3 NSCLC DA yields comparable results to pathologist interpretation while eliminating the intra- and inter-pathologist variability associated with manual scoring while providing characterization of the immune microenvironment, which can aid in clinical treatment decisions.

Targeting treatment options for castration-resistant prostate cancer.

Prostate cancer (PCa) is the most commonly diagnosed solid tumor and the second leading cause of cancer-related deaths in U.S. men in 2020. Androgen-deprivation therapy (ADT) is the standard of care for metastatic PCa. Unfortunately, PCa relapse often occurs one to two years after initiation of ADT, resulting in the development of castration-resistant PCa (CRPCa), a lethal disease. While several anticancer agents such as docetaxel, abiraterone acetate, and enzalutamide are currently utilized to extend a patient's life after development of CRPCa, patients will eventually succumb to the disease. Hence, while targeting androgen signaling and utilization of docetaxel remain the most crucial agents for many of these combinations, many studies are attempting to exploit other vulnerabilities of PCa cells, such as inhibition of key survival proteins, anti-angiogenesis agents, and immunotherapies. This review will focus on discussing recent advances on targeting therapy. Several novel small molecules will also be discussed.

Autophagy and organelle homeostasis in cancer.

Beginning with the earliest studies of autophagy in cancer, there have been indications that autophagy can both promote and inhibit cancer growth and progression; autophagy regulation of organelle homeostasis is similarly complicated. In this review we discuss pro- and antitumor effects of organelle-targeted autophagy and how this contributes to several hallmarks of cancer, such as evading cell death, genomic instability, and altered metabolism. Typically, the removal of damaged or dysfunctional organelles prevents tumor development but can also aid in proliferation or drug resistance in established tumors. By better understanding how organelle-specific autophagy takes place and can be manipulated, it may be possible to go beyond the brute-force approach of trying to manipulate all autophagy in order to improve therapeutic targeting of this process in cancer.

A novel pregnene analogs: synthesis, cytotoxicity on prostate cancer of PC-3 and LNCPa-AI cells and in silico molecular docking study.

New pregnene analogs of N-hydroxamic acid 6, imino-propane hydrazides 7 and 8 as well as the aryl amides 9-11, oxadiazole, pyrazole and sulfinyl analogs 13-15, via the hydrazide analog 5 of methyl ((5-pregnen-3ß,17ß-diol-15α-yl)thio)propanoate (4) were synthesized. The in vitro cytotoxic activities of selected synthesized steroids against two human prostate cancer cell lines (PC-3, and LNCaP-AI) were evaluated by MTT assay. Compound 10 was the most active cytotoxic agent among these steroids against PC-3 and LNCaP-AI cell lines with inhibition of 96.2%, and 93.6% at concentration levels of 10.0 µM and 91.8%, and of 79.8% at concentration of 1.0 µM, respectively. Molecular docking study of 10 showed a hydrogen bonding with the amino acid Asn705 residue of the receptor 1E3G, together with hydrophobic interactions. Therefore, compound 10 can be considered as a promising anticancer agent due to its potent cytotoxic activity.

The interplay of autophagy and non-apoptotic cell death pathways.

Autophagy, the process of macromolecular degradation through the lysosome, has been extensively studied for the past decade or two. Autophagy can regulate cell death, especially apoptosis, through selective degradation of both positive and negative apoptosis regulators. However, multiple other programmed cell death pathways exist. As knowledge of these other types of cell death expand, it has been suggested that they also interact with autophagy. In this review, we discuss the molecular mechanisms that comprise three non-apoptotic forms of cell death (necroptosis, pyroptosis and ferroptosis) focusing on how the autophagy machinery regulates these different cell death mechanisms through (i) its degradative functions, i.e., true autophagy, and (ii) other non-degradative functions of the autophagy machinery such as serving as a signaling scaffold or by participating in other autophagy-independent cellular processes.

ErbB-2 signaling in advanced prostate cancer progression and potential therapy

Currently, prostate cancer (PCa) remains the most commonly diagnosed solid tumor and the second leading cause of cancer-related deaths in US men. Most of these deaths are attributed to the development of castration-resistant (CR) PCa. ErbB-2 and ErbB family members have been demonstrated to contribute to the progression of this lethal disease. In this review, we focus on updating the role of ErbB-2 in advanced PCa progression and its regulation, including its regulation via ligand activation, miRNAs and protein phosphorylation. We also discuss its downstream signaling pathways, including AKT, ERK1/2 and STATs, involved in advanced PCa progression. Additionally, we evaluate the potential of ErbB-2, focusing on its protein hyper-phosphorylation status, as a biomarker for aggressive PCa as well as the effectiveness of ErbB-2 as a target for the treatment of CR PCa via a multitude of approaches, including orally available inhibitors, intratumoral expression of cPAcP, vaccination and immunotherapy.

p66Shc protein through a redox mechanism enhances the progression of prostate cancer cells towards castration-resistance.

Prostate cancer (PCa) remains the second leading cause of cancer-related deaths in U.S. men due to the development of the castration-resistant (CR) PCa phenotype. A useful cell model for analysis of the molecular mechanism of PCa progression is required for developing targeted therapies toward CR PCa. In this study, we established a PCa cell progressive model in three separate cell lines, of which androgen-independent (AI) cells were derived from respective androgen-sensitive (AS) cells. Those AI PCa cells obtain the biochemical properties of the clinical CR phenotype, including AR and PSA expression as well as enhanced proliferation and tumorigenicity under androgen-deprived conditions. Thus, those AI cells recapitulate CR PCa and exhibit increased oxidant species levels as well as enhanced signaling of proliferation and survival pathways. H2O2 treatment directly enhanced AS cell growth and migration, which was counteracted by antioxidant N-acetyl cysteine (NAC). We further identified p66Shc protein enhances the production of oxidant species which contributes to phenotypic and cell signaling alterations from AS to AI PCa cells. H2O2-treated LNCaP-AS cells had a similar signaling profile to that of LNCaP-AI or p66Shc subclone cells. Conversely, the oxidant species-driven alterations of LNCaP-AI and p66Shc subclone cell signaling is mitigated by p66Shc knockdown. Moreover, LNCaP-AI cells and p66Shc subclones, but not LNCaP-AS cells, develop xenograft tumors with metastatic nodules, correlating with p66Shc protein levels. Together, the data shows that p66Shc enhances oxidant species production that plays a role in promoting PCa progression to the CR stage.

Novel CIL-102 derivatives as potential therapeutic agents for docetaxel-resistant prostate cancer.

The standard-of-care treatment for metastatic prostate cancer (PCa) is androgen deprivation therapy (ADT). Nevertheless, most tumors eventually relapse and develop into lethal castration-resistant prostate cancer (CRPC). Docetaxel is a FDA-approved agent for the treatment of CRPC; however, the tumor often quickly develops resistance to this drug. Thus, there is an immediate need for novel therapies to treat docetaxel-resistant PCa. In this study, we modified the structure of CIL-102 and investigated the efficacy of the derivatives against CRPC and docetaxel-resistant PCa. These novel CIL-102 derivatives inhibit CRPC tumorigenicity, including proliferation, migration and colony formation, and importantly, selectively inhibit CRPC cell proliferation over non-cancerous prostate epithelia. Computational modeling indicated the derivatives bind to ß-tubulin and immunocytochemistry revealed the depolymerization of microtubules upon treatment. Western blot analyses reveal that pro-apoptotic and anti-oxidant pathways are activated, and MitoSOX and DCF-DA analyses confirmed increased reactive oxygen species (ROS) production upon treatments. Furthermore, CIL-102 derivatives effectively reduce the proliferation of docetaxel-resistant CR PCa cell lines. Our data indicate the potential of these compounds as promising therapeutic agents for CRPC as well as docetaxel-resistant CRPC.

p66Shc regulates migration of castration-resistant prostate cancer cells.

Metastatic castration-resistant (CR) prostate cancer (PCa) is a lethal disease for which no effective treatment is currently available. p66Shc is an oxidase previously shown to promote androgen-independent cell growth through generation of reactive oxygen species (ROS) and is elevated in clinical PCa and multiple CR PCa cell lines. We hypothesize p66Shc also increases the migratory activity of PCa cells through ROS and investigate the associated mechanism. Using the transwell assay, our study reveals that the level of p66Shc protein correlates with cell migratory ability across several PCa cell lines. Furthermore, we show hydrogen peroxide treatment induces migration of PCa cells that express low levels of p66Shc in a dose-dependent manner, while antioxidants inhibit migration. Conversely, PCa cells that express high levels of endogenous p66Shc or by cDNA transfection possess increased cell migration which is mitigated upon p66Shc shRNA transfection or expression of oxidase-deficient dominant-negative p66Shc W134F mutant. Protein microarray and immunoblot analyses reveal multiple proteins, including ErbB-2, AKT, mTOR, ERK, FOXM1, PYK2 and Rac1, are activated in p66Shc-elevated cells. Their involvement in PCa migration was examined using respective small-molecule inhibitors. The role of Rac1 was further validated using cDNA transfection and, significantly, p66Shc is found to promote lamellipodia formation through Rac1 activation. In summary, the results of our current studies clearly indicate p66Shc also regulates PCa cell migration through ROS-mediated activation of migration-associated proteins, notably Rac1.

Anti-Androgen Abiraterone Acetate Improves the Therapeutic Efficacy of Statins on Castration-Resistant Prostate Cancer Cells.

The treatment of castration-resistant (CR) prostate cancer (PCa) is limited. A sub-population of CR PCa tumors can synthesize androgens for intracrine androgen receptor (AR) activation, thus targeting androgen biosynthesis could be an effective therapeutic option for these patients. We determined that androgen biosynthesis inhibitors simvastatin, atorvastatin, and ketoconazole directly inhibit growth, migration, and colony formation of LNCaP C-81 cells, which exhibit de novo androgen biosynthesis, with simvastatin being the most effective. Importantly, in combination treatments, statins specifically enhanced growth suppression with added effects by anti-androgen abiraterone acetate on the CR PCa cells. Thus, statins can be used in conjunction with abiraterone acetate to enhance anti-androgen therapy for CR PCa.

Statin derivatives as therapeutic agents for castration-resistant prostate cancer.

Despite recent advances in modern medicine, castration-resistant prostate cancer remains an incurable disease. Subpopulations of prostate cancer cells develop castration-resistance by obtaining the complete steroidogenic ability to synthesize androgens from cholesterol. Statin derivatives, such as simvastatin, inhibit cholesterol biosynthesis and may reduce prostate cancer incidence as well as progression to advanced, metastatic phenotype. In this study, we demonstrate novel simvastatin-related molecules SVA, AM1, and AM2 suppress the tumorigenicity of prostate cancer cell lines including androgen receptor-positive LNCaP C-81 and VCaP as well as androgen receptor-negative PC-3 and DU145. This is achieved through inhibition of cell proliferation, colony formation, and migration as well as induction of S-phase cell-cycle arrest and apoptosis. While the compounds effectively block androgen receptor signaling, their mechanism of inhibition also includes suppression of the AKT pathway, in part, through disruption of the plasma membrane. SVA also possess an added effect on cell growth inhibition when combined with docetaxel. In summary, of the compounds studied, SVA is the most potent inhibitor of prostate cancer cell tumorigenicity, demonstrating its potential as a promising therapeutic agent for castration-resistant prostate cancer.