Human Kallikrein Research Articles

Unveiling therapeutic frontiers: DON/DRP-104 as innovative Plasma kallikrein inhibitors against carcinoma-associated hereditary angioedema shocks - a comprehensive molecular dynamics exploration

Human plasma kallikrein (PKa) is a member of the serine protease family and serves as a key mediator of the kallikrein-kinin system (KKS), which is known for its regulatory roles in inflammation, vasodilation, blood pressure, and coagulation. Genetic dysregulation of KKS leads to Hereditary Angioedema (HAE), which is characterized by spontaneous, painful swelling in various body regions. Importantly, HAE frequently coexists with various cancers. Despite substantial efforts towards the development of PKa inhibitors for HAE, there remains a need for bifunctional agents addressing both anti-cancer and anti-HAE aspects, especially against carcinoma-associated comorbid HAE conditions. Consequently, we investigated the therapeutic potential of the anti-glutamine prodrug, isopropyl(S)-2-((S)-2-acetamido-3-(1H-indol-3-yl)-propanamido)-6-diazo-5-oxo-hexanoate (DRP-104), and its active form, 6-Diazo-5-oxo-l-norleucine (DON), recognized for their anti-cancer properties, as novel PKa inhibitors. Utilizing structure-based in silico methods, we conducted a comparative analysis with berotralstat, a clinically approved HAE prophylactic, and sebetralstat, an investigational HAE therapeutic agent, in Phase 3 clinical trials. Inhibiting PKa with DON resulted in relatively heightened structural stability, rigidity, restricted protein folding, and solvent-accessible loop exposure, contributing to increased intra-atomic hydrogen bond formation. Conversely, PKa inhibition with DRP-104 induced restricted residue flexibility and significantly disrupted the critical SER195-HIS57 arrangement in the catalytic triad. Both DON and DRP-104, along with the reference drugs, induced strong cooperative intra-residue motion and bidirectional displacement in the PKa architecture. The results revealed favorable binding kinetics of DON/DRP-104, showing thermodynamic profiles that were either superior or comparable to those of the reference drugs. These findings support their consideration for clinical investigations into the management of carcinoma-associated HAE.

A Phase 0 Study to Assess the Biodistribution and Pharmacokinetics of a Radiolabeled Antibody Targeting Human Kallikrein 2 in Participants with Metastatic Castration-Resistant Prostate Cancer.

Despite the inclusion of multiple agents within the prostate cancer treatment landscape, new treatment options are needed to address the unmet need for patients with metastatic castration-resistant prostate cancer (mCRPC). Although prostate-specific membrane antigen is the only cell-surface target to yield clinical benefit in men with advanced prostate cancer, additional targets may further advance targeted immune, cytotoxic, radiopharmaceutical, and other tumor-directed therapies for these patients. Human kallikrein 2 (hK2) is a novel prostate-specific target with little to no expression in nonprostate tissues. This first-in-human phase 0 trial uses an 111In-radiolabeled anti-hK2 monoclonal antibody, [111In]-DOTA-h11B6, to credential hK2 as a potential target for prostate cancer treatment. Methods: Participants with progressive mCRPC received a single infusion of 2 mg of [111In]-DOTA-h11B6 (185 MBq of 111In), with or without 8 mg of unlabeled h11B6 to assess antibody mass effects. Sequential imaging and serial blood samples were collected to determine [111In]-DOTA-h11B6 biodistribution, dosimetry, serum radioactivity, and pharmacokinetics. Safety was assessed within a 2-wk follow-up period from the time of [111In]-DOTA-h11B6 administration. Results: Twenty-two participants received [111In]-DOTA-h11B6 and are included in this analysis. Within 6-8 d of administration, [111In]-DOTA-h11B6 visibly accumulated in known mCRPC lesions, with limited uptake in other organs. Two treatment-emergent adverse events unrelated to treatment occurred, including tumor-related bleeding in 1 patient, which led to early study discontinuation. Serum clearance, biodistribution, and tumor targeting were independent of total antibody mass (2 or 10 mg). Conclusion: This first-in-human study demonstrates that tumor-associated hK2 can be identified and targeted using h11B6 as a platform as the h11B6 antibody selectively accumulated in mCRPC metastases with mass-independent clearance kinetics. These data support the feasibility of hK2 as a target for imaging and hK2-directed agents as potential therapies in patients with mCRPC.

Manzamine A reduces androgen receptor transcription and synthesis by blocking E2F8-DNA interactions and effectively inhibits prostate tumor growth in mice.

The androgen receptor (AR) is the main driver in the development of castration-resistant prostate cancer, where the emergence of AR splice variants leads to treatment-resistant disease. Through detailed molecular studies of the marine alkaloid manzamine A (MA), we identified transcription factor E2F8 as a previously unknown regulator of AR transcription that prevents AR synthesis in prostate cancer cells. MA significantly inhibited the growth of various prostate cancer cell lines and was highly effective in inhibiting xenograft tumor growth in mice without any pathophysiological perturbations in major organs. MA suppressed the full-length AR (AR-FL), its spliced variant AR-V7, and the AR-regulated prostate-specific antigen (PSA; also known as KLK3) and human kallikrein 2 (hK2; also known as KLK2) genes. RNA sequencing (RNA-seq) analysis and protein modeling studies revealed E2F8 interactions with DNA as a potential novel target of MA, suppressing AR transcription and its synthesis. This novel mechanism of blocking AR biogenesis via E2F8 may provide an opportunity to control therapy-resistant prostate cancer over the currently used AR antagonists designed to target different parts of the AR gene.

Preclinical characterization of human Kallikrein 2 (hK2) as a novel target for the treatment of prostate cancer.

202 Background: Treatment options that are durably effective for patients with metastatic (m) castration-resistant prostate cancer (CRPC) remain limited despite available therapies, highlighting a continued unmet need for novel drug development. hK2 is overexpressed in prostate cancer (PC) and has little to no expression in non-prostate tissues. Here, we use a series of preclinical experiments to evaluate hK2 as a therapeutic target in PC. Methods: hK2 expression was assessed by immunohistochemistry (IHC) in non-metastatic (nm) castration sensitive PC (CSPC; n = 100), mCSPC (n = 98), and mCRPC (n = 45) samples obtained from tumor banks and warm autopsy tumor microarrays. Multiplex immunofluorescence (IF) was used to assess hK2 expression at different mCRPC tumor sites. hK2 cell surface expression in a human prostate cancer cell model (VCaP) and fresh mCRPC patient tumor samples was assessed by flow cytometry. hK2-targeting antibody internalization over time was visualized by confocal IF microscopy in VCaP cells. VCaP xenograft models in immune-compromised NSG mice were used to evaluate anti-tumor activity, defined as change in percent of tumor growth inhibition (ΔTGI), following treatment with 3 unique hK2-targeting experimental agents (Table). Whole-body planar and SPECT/CT imaging were used to assess hK2-targeting antibody tumor uptake in patients with mCRPC. Results: IHC confirmed robust hK2 expression across different PC stages with homogenous expression in nm/mCSPC and increased heterogeneity in mCRPC. Mean percent tumor staining of hK2 in mCRPC samples was 67.6% (bone), 65.7% (lymph nodes), and 33.5% (liver) by multiplex IF. Correlation of hK2 expression across mCRPC bony lesions (r = 0.74, p < 1.6e-06) was observed, suggesting intrapatient and interlesion homogeneity. Confocal microscopy demonstrated hK2 cell surface expression in VCaP cells, with rapid antibody internalization within 3 hours. Flow cytometry confirmed hK2 cell surface expression in both VCaP cells and mCRPC samples. Robust antitumor activity was observed following treatment with each hK2-targeting agent in the xenograft mouse model (Table). Whole-body and SPECT/CT scans confirmed accumulation of the hK2-targeting antibody to PC tumors in patients with mCRPC. Conclusions: hK2 expression was homogenous in nm/mCSPC, with increased heterogeneity in mCRPC. Antitumor activity was observed across hK2-targeting agents. These data demonstrate that therapeutic strategies targeting hK2 hold promise in PC treatment and support further investigation of these agents in clinical studies. [Table: see text]

Bioinformatics analysis of human kallikrein 5 (KLK5) expression in metaplastic triple-negative breast cancer.

Metaplastic breast carcinoma (MBC) is a rare breast cancer subtype; most cases are triple-negative breast cancers (TNBCs) and are poorly responsive to conventional systemic therapy. Few potential diagnostic and prognostic markers for distinguishing between metaplastic TNBC and nonmetaplastic TNBC have been discovered. We performed bioinformatic analysis to explore the underlying mechanism by which metaplastic TNBC differs from nonmetaplastic TNBC and provides potential pathogenic genes of metaplastic TNBC. Differentially expressed genes (DEGs) in metaplastic tumors and nonmetaplastic tumors from TNBC patients were screened using GSE165407. The GSE76275 data set and The Cancer Genome Atlas (TCGA) database were used to screen DEGs in TNBC and non-TNBC. Metascape and DAVID were used for the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis and Gene Ontology (GO) analysis of DEGs. Online databases, including UALCAN, GEPIA, HPA, Breast Cancer Gene-Expression Miner, andquantitativePCRand western blot, were used to examine KLK5messenger RNAand protein expression in breast cancer. Analysis of KLK5‑associated genes was performed with TCGA data, and the LinkedOmics database was used to detect the genes co-expressed with KLK5. STRING (Search Tool for the Retrieval of Interacting Genes) and Cytoscape were used to screen for hub genes. Kaplan‑Meier plotter was used for survival analysis. KLK5 was identified among the DEGs in nonmetaplastic TNBC and metaplastic TNBC. The KLK5 gene was overexpressed in nonmetaplastic TNBC but downregulated in metaplastic TNBC. KEGG and GO analyses revealed that epithelial-to-mesenchymal transitionwas a pathogenic mechanism in metaplastic TNBC and an important pathway by which KLK5 and its associated genes DSG1 and DSG3 influence metaplastic TNBC progression. Prognosis analysis showed that only low expression of KLK5 in metaplastic TNBC had clinical significance. Our research indicated that KLK5 may be a pivotal molecule with a key role in the mechanism of tumorigenesis in metaplastic TNBC.

Human plasma kallikrein: roles in coagulation, fibrinolysis, inflammation pathways, and beyond.

Human plasma kallikrein (PKa) is obtained by activating its precursor, prekallikrein (PK), historically named the Fletcher factor. Human PKa and tissue kallikreins are serine proteases from the same family, having high- and low-molecular weight kininogens (HKs and LKs) as substrates, releasing bradykinin (Bk) and Lys-bradykinin (Lys-Bk), respectively. This review presents a brief history of human PKa with details and recent observations of its evolution among the vertebrate coagulation proteins, including the relations with Factor XI. We explored the role of Factor XII in activating the plasma kallikrein-kinin system (KKS), the mechanism of activity and control in the KKS, and the function of HK on contact activation proteins on cell membranes. The role of human PKa in cell biology regarding the contact system and KSS, particularly the endothelial cells, and neutrophils, in inflammatory processes and infectious diseases, was also approached. We examined the natural plasma protein inhibitors, including a detailed survey of human PKa inhibitors' development and their potential market.

HKLK alleviates myocardial fibrosis in mice with viral myocarditis.

Myocardial fibrosis is the most serious complication of viral myocarditis (VMC). This study aimed to investigate the therapeutic benefits and underlying mechanisms of lentivirus-mediated human tissue kallikrein gene transfer in myocardial fibrosis in VMC mice. We established VMC mouse model via intraperitoneal injection with Coxsackie B3 virus. The effect was then assessed after treatment with vehicle, the empty lentiviral vectors (EZ.null), and the vectors expressing hKLK1 (EZ.hKLK1) via tail vein injection for 30 days, respectively. The results showed that administering EZ.hKLK1 successfully induced hKLK1 overexpression in mouse heart. Compared with EZ.null treatment, EZ.hKLK1 administration significantly reduced the heart/weight ratio, improved cardiac function, and ameliorated myocardial inflammation in VMC mice, suggesting that hKLK1 overexpression alleviates VMC in mice. EZ.hKLK1 administration also significantly abrogated the increased myocardial collagen content, type I/III collagen ratio, TGF-β1 mRNA and protein expression in VMC mice, suggesting that hKLK1 overexpression reduces collagen accumulation and blunts TGF-β1 signaling in the hearts of VMC mice. In conclusion, our results suggest that hKLK1 alleviates myocardial fibrosis in VMC mice, possibly by downregulating TGF-β1 expression.

Human Kallikrein-2 and Free Prostate Specific Antigen as Biomarkers for Early Detection of Prostate Cancer, Sudan: A Case-Control Study

Background: Prostate cancer (PCa) is considered one of the major health threats facing males in Sudan. Prostate-specific antigen (PSA) test is the most important laboratory test used in the diagnosis of prostate cancer, the main disadvantage of PSA is its limited specificity, which triggered a lot of interest in development, more research on other markers such as serum human kallikrein-2 (KLK-2) and free prostate specific antigen (fPSA). Objectives: To evaluate the validity of serum kallikrein-2 (KLK-2) and free prostate specific antigen (fPSA) in the early detection of prostate cancer among Sudanese patients. Method: In this study seventy men were considered as a case subject, who were diagnosed as cancer prostate at Gezira Hospital for Renal Disease and Surgery (GHRDS), Sudan during the period February 2018 to July 2019. Randomly selected sixty patients of BPH patients and forty-five apparently healthy men as control subject. KLK-2, fPSA and PSA estimations were performed from serum samples using the principle of Enzyme Linked Immunosorbent Assay (ELISA). Results: The results revealed a highly significant difference between the serum levels individual biomarkers (KLK-2, fPSA, PSA) and multiple biomarkers (fPSA/PSA, KLK-2/fPSA, KLK-2/PSA) for patients with prostate cancer when compared with the control groups. Furthermore, the fPSA/PSA ratio was lower in the patients with prostate cancer (P value = 0.00) than in the control group, the fPSA/PSA ratio showed that best accuracy to differentiate prostate cancer from control group, fPSA cut-off value was found to be more than (18 ng/ml), with sensitivity (93%), specificity (80%), and odds ratio (55). Conclusions: The use of multiple biomarkers rather than individual biomarkers especially fPSA/PSA ratio improves the specificity as well as maintenance of higher sensitivity for early diagnosis of the prostate cancer.

Observation of Serological Index and Efficacy of Abiraterone Hydrochloride Tablets Combined with Endocrine Therapy in Patients with Metastatic Castration-Resistant Prostate Cancer.

This study reviewed and analysed the serological indexes, clinical efficacy and common clinical indexes of patients with metastatic castration-resistant prostate cancer (mCRPC) treated with combination of abiraterone hydrochloride tablets and endocrine therapy. This study is a retrospective analysis. A total of 133 mCRPC patients who were admitted to our hospital from January 2019 to December 2021 were selected as the study subjects. The patients were categorised into the experimental group (n = 51) and control group (n = 82) according to their treatment method. The control group was treated with docetaxel combined with endocrine therapy, whilst the experimental group was treated with combination therapy with abiraterone hydrochloride tablets. Subsequently, the clinical data of the two groups, including serum insulin-like growth factor-1 (IGF-1), human glandular kallikrein 2 (hK2), prostate specific antigen (PSA), vascular endothelial growth factor (VEGF) and serum carcinoembryonic antigen (CEA), were analysed. The overall response rate of the experimental group (84.3%) was higher than that of the control group (72.0%). The serum levels of CEA, total prostate specific antigen, free prostate specific antigen, testosterone and androgen receptor splice variant 7 in both groups were lower than those of before treatment, and the values obtained by the experimental group were lower than those of the control group (p < 0.05). After treatment, the levels of CD3+, CD4+ and CD4+/CD8+ in both groups were higher than those before treatment, and the levels of CD8+, IGF-1, hK2, PSA and VEGF in the two groups decreased after treatment (p < 0.05). The use of abiraterone hydrochloride tablet combined with endocrine therapy for patients with mCRPC is effective and can improve clinical symptoms and serum cytokine levels.

Activity assay based on the immobilized enzyme kallikrein and mass spectrometry

Deregulated activity and expression of human kallikreins (KLKs) may be involved in various pathologies, so these enzymes are an attractive biological target for identifying molecules that can modulate KLK activity. This identification involves applying fast and efficient screening methods. This work describes an off-line assay with mass spectrometry (MS) detection that uses KLK immobilized on Sepharose-NHS as a micro-column configuration (IMER-KLK-Sepharose-NHS). The mass spectrometry used has an ion trap analyzer and electrospray ionization (EIS). The HPLC-MS method for quantifying KLK activity was developed. The enzymatic assay conditions were optimized, and the IMER-KLK-Sepharose-NHS kinetic parameter (KMapp = 15.48 ± 3 μmol L−1) was evaluated. Finally, the method was validated by using leupeptin as a reference inhibitor (IC50 = 0.85 ± 0.10 μmol L−1). The developed method was able to identify the reference inhibitor and can be an alternative for screening KLK inhibitors.

Evaluation the level of human kallikrein-2-hk2, prostate specific antigen and some biochemical parameters in sera of patients with prostate disease

The study was conducted on 90 serum samples of people with prostate diseases (G1-include 24 samples for patients with prostate cancer-PC , G2- include 24 samples for patients with benign prostatic hyperplasia-BPH and 22 samples for patients with prostatitis G3), compared with 20 samples for healthy individuals as control group. Prostate-specific antigen-PSA, human kallikrein-2-hK2, fibrinogen gamma-FGG, total anti-oxidant capacity-TAC, Vitamin D3-VD3. The results showed that the activity of PSA significantly elevated in G1 andG3 with no significant difference in G2, with significant increase in G1 for PSA and the hK2, FGG and TAC. so The results showed a significant increase in the group G2 in human kallikrein-2 with no significant difference in G3 compared with control group, and a significant increase in FGG levels in the group G2 and G3 compared with control group with no significant difference between G3, G1 with a significant increase in the group G2 and G3 in TAC levels compared with the control group , with significant decreased in VD3 levels in group G3 and no significant difference in groups G1, G2 compared with control group.

Structural and functional properties of rBmTI-A: A Kunitz-BPTI serine protease inhibitor with therapeutical potential

Serine proteases are an important group of enzymes present in several organisms such as viruses, bacteria and eukaryotes involved in several physiological and pathological processes such as cancer, neurodegeneration, tissue inflammation and infections. Kunitz-type serine protease inhibitors have been studied as therapeutical targets with positive results in many of these diseases. rBmTI-A (recombinant B. microplus Trypsin Inhibitor A) is a Kunitz-BPTI type inhibitor based on the native protein BmTI-A. BmTI-A was extracted from tick larvae and presented inhibitory activity against trypsin, human plasma kallikrein (HuPK), human neutrophil elastase (HNE) and human plasmin. rBmTI-A presented the same inhibitory activities of the BmTI-A and its thermostability has already been demonstrated. In emphysema induced by porcine pancreatic elastase (PPE) and by cigarette smoke animal models, the treatment using rBmTI-A showed a protective effect against the development of pulmonary emphysema and prevented the increase of inflammatory cells. In chronic allergic animal model, rBmTI-A treatment resulted in attenuated bronchial hyperresponsiveness, inflammation, remodeling. These are important physiological results in emphysema and lung inflammatory animal models with rBmTI-A treatment confirming its therapeutical potential.

The family of kallikrein-related peptidases and kinin peptides as modulators of epidermal homeostasis.

The epidermis is the outermost skin layer and is part of one of the largest organs in the body; it is supported by the dermis, a network of fibrils, blood vessels, pilosebaceous units, sweat glands, nerves, and cells. The skin as a whole is a protective shield against numerous noxious agents, including microorganisms and chemical and physical factors. These functions rely on the activity of multiple growth factors, peptide hormones, proteases, and specific signaling pathways that are triggered by the activation of distinct types of receptors sited in the cell membranes of the various cell types present in the skin. The human kallikrein family comprises a large group of 15 serine proteases synthesized and secreted by different types of epithelial cells throughout the body, including the skin. At this site, they initiate a proteolytic cascade that generates the active forms of the proteases, some of which regulate skin desquamation, activation of cytokines, and antimicrobial peptides. Kinin peptides are formed by the action of plasma and tissue kallikreins on kininogens, two plasma proteins produced in the liver and other organs. Although kinins are well known for their proinflammatory abilities, in the skin they are also considered important modulators of keratinocyte differentiation. In this review, we summarize the contributions of the kallikreins and kallikrein-related peptidases family and those of kinins and their receptors in skin homeostasis, with special emphasis on their pathophysiological role.

Phase 1 study of JNJ-69086420, an actinium-225-labeled antibody targeting human kallikrein-2, for advanced prostate cancer.

TPS5104 Background: Radioligand therapy for metastatic castration resistant prostate cancer (mCRPC) has been shown to prolong survival, delay disease progression, and improve quality of life, raising hopes that these gains will be amplified with even more cancer-specific targets and more powerful radioligands. Human kallikrein-related peptidase 2 (hK2) is a tumor-associated member of the kallikrein family that shares significant homology to prostate-specific antigen and is minimally expressed in normal non-prostate tissues. JNJ-69086420 (JNJ-420; 225Ac-DOTA-h11B6 [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]), is a first-in-class radioimmunotherapy targeted to hK2 antigen. In a phase 0 study of [111In]-DOTA-h11B6, patients with mCRPC (progressed on standard therapies), treatment with a single dose of [111In]-DOTA-h11B6 (2 mg) with/without 8 mg h11B6, demonstrated safety, good tumor localization, nominal normal-organ uptake, and no difference in pharmacokinetics (PK) between 2 and 10 mg antibody mass (Morris et al. J Clin Oncol. 2021 39:6 suppl, 122). We have initiated the first-in-human study to assess the safety, PK, pharmacodynamic (PD), and clinical activity of Ac-225 radiolabeled JNJ-420, to determine its recommended phase 2 dose (RP2D) in adults with advanced PC. Methods: This open-label, multicenter, phase 1 study will recruit approximately 50 men (aged ≥18 years) with advanced PC across dose escalation (Part 1) and expansion (Part 2) parts. Key eligibility criteria: mCRPC with histologic confirmation of adenocarcinoma, Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, adequate organ function based on hematology and serum chemistry, and 1 or more prior novel androgen receptor-targeted therapies (prior chemotherapy acceptable). Key exclusion criteria: prior treatment with radium/strontium/samarium/radioconjugate therapy, superscan findings as protocol defined, active central nervous system metastases. In Part 1, men will receive intravenous (IV) injection of 50 μCi/ 2 mg JNJ-420 (once every 8 weeks) with one or multiple doses; escalation of dose levels to be based on dose limiting toxicities (DLTs) evaluation, until RP2D identification. In Part 2, JNJ-420 is to be given at one of the RP2D(s) determined in Part 1. Primary endpoint is safety (incidence and severity [grading per NCI-CTCAE V5.0] of AEs including DLTs). Secondary endpoints include prostate specific antigen response rate, overall response rate (PCWG3 modified RECIST 1.1 criteria), PK, PD, immunogenicity, and biomarker analyses. Enrollment began in Dec 2020; as of 10 Feb 2022, 4 sites have been initiated and 23 patients enrolled; currently, dose escalation is ongoing. Clinical trial information: NCT04644770.

Correlation analysis between CD133, Klk3 and grhl2 expression and tumor characteristics in prostate cancer.

Prostate cancer is a common clinical disease in men. It is known that prostate cancer ranks 3rd in the incidence of malignant tumors of the male genitourinary system in China, which is able to evaluate the riskiness of life expectancy of male patients. Therefore, we investigated the expression of CD133, recombinant human kallikrein 3 (Klk3), grainy head like 2 (grhl2) in prostate cancer, and correlation with tumor characteristics in the present study. A total of 167 prostate cancer patients who underwent surgical treatment in our hospital from February 2017 to April 2021 were selected. Their cancer and adjacent tissues were resected, and CD133 was detected by double staining using immunohistochemistry, Klk3 and grhl2 were detected by RT-PCR analysis, and CD133, Klk3 were analyzed by Pearson's method in different clinical stages, Gleason grade Correlation of grhl2 with tumor characteristics. The expression of CD133, KLK3, and GRHL2 in cancer tissue was increased compared with adjacent tissue (P < 0.05). The expression of CD133, KLK3, and GRHL2 increased with the aggravation of the clinical stage and Gleason grade (P < 0.05). CD133, KLK3, and GRHL2 showed a positive correlation in prostate cancer. The Pearson method found a positive correlation between CD133, KLK3, GRHL2 and clinical stage, Gleason grade, and lymph node metastasis. In general, high CD133, Klk3, and grhl2 expression was observed in prostate cancer and increased with the disease. They presented a positive correlation in prostate cancer presence, and these three gene products correlated with tumor characteristics.

Phase 1 study of JNJ-69086420, an actinium-225-labeled antibody targeting human kallikrein-2, for advanced prostate cancer.

TPS206 Background: Radioligand therapy for metastatic castration resistant prostate cancer (mCRPC) has been shown to prolong survival, delay disease progression, and improve quality of life, raising hopes that these gains will be amplified with even more cancer-specific targets and more powerful radioligands. Human kallikrein-related peptidase 2 (hK2) is a tumor-associated member of the kallikrein family that shares significant homology to prostate-specific antigen and is minimally expressed in normal non-prostate tissues. JNJ-69086420 (JNJ-420; 225Ac-DOTA-h11B6 [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]), is a first-in-class radioimmunotherapy targeted to hK2 antigen. In a phase 0 study of [111In]-DOTA-h11B6, patients (pts) with mCRPC (progressed on standard therapies), treatment with a single dose of [111In]-DOTA-h11B6 (2 mg) with/without 8 mg h11B6, demonstrated safety, good tumor localization, nominal normal-organ uptake, and no difference in PK between 2 and 10 mg antibody mass (Morris et al. J Clin Oncol. 2021 39:6 suppl, 122). We have initiated the first-in-human study to assess the safety, pharmacokinetics (PK), pharmacodynamic (PD), and clinical activity of Ac-225 radiolabeled JNJ-420, to determine its recommended phase 2 dose (RP2D) in adults with advanced PC. Methods: This open-label, multicenter, phase 1 study will recruit approximately 50 men (aged ≥18 years) with advanced PC across dose escalation (Part 1) and expansion (Part 2) parts. Key eligibility criteria: mCRPC with histologic confirmation of adenocarcinoma, Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, adequate organ function based on hematology and serum chemistry, and 1 or more prior novel androgen receptor-targeted therapies (prior chemotherapy acceptable). Key exclusion criteria: prior treatment with radium/strontium/samarium/radioconjugate therapy, superscan findings as protocol defined, active central nervous system metastases. In Part 1, men will receive intravenous (IV) injection of 50 μCi/ 2 mg JNJ-420 (once every 8 weeks) with one or multiple doses; escalation of dose levels to be based on dose limiting toxicities (DLTs) evaluation, until RP2D identification. In Part 2, JNJ-420 is to be given at one of the RP2D(s) determined in Part 1. Primary endpoint is safety (incidence and severity [grading per NCI-CTCAE V5.0] of AEs including DLTs). Secondary endpoints include prostate specific antigen response rate, overall response rate (PCWG3 modified RECIST 1.1 criteria), PK, PD, immunogenicity, and biomarker analyses. Enrollment began in Dec 2020; as of Sep 2021, 4 sites have been initiated and 14 pts enrolled; currently, dose escalation is ongoing. Clinical trial information: NCT04644770.

Expression of tissue PSA in breast cancer is associated with less aggressive disease and lower chance of tumor relapse

Background: Human kallikrein 3 (hK3), also known as Prostatic specific antigen (PSA), was considered as one of the most useful markers for the detection as well as management of prostate cancer. While PSA was thought to be a prostatic tissue-specific protein, many reports suggest the presence of extraprostatic PSA in different tissues, including the breast. Few reports showed PSA immunoreactivity in breast cancer tissues and suggest a favorable prognostic role of PSA in breast cancer. However, most of those studies were not conclusive or restricted to small scale studies limiting their clinical significance. Methods: We used a bioinformatical approach to investigate the association between tissue PSA expression levels and different clinicopathological parameters in breast cancer using different publicly available databases. Further validation was done using our patient cohort of 40 surgical breast samples obtained from patients attending Al Kadhemyia Teaching Hospital – Iraq. Results: Using a cohort of 593 breast lesion samples extracted from the TCGA database using the ONCOMINE database, our results showed no significant upregulation of PSA mRNA levels in breast cancer samples compared to healthy tissue (P = 0.1). The same trend was also observed in our patient cohort with positive immunoreactivity in 50% (5 samples) of benign lesions compared to 36.66% (11 samples) in breast cancer samples. In addition, investigating the correlation between mRNA PSA expression and different clinicopathological parameters using the Breast Cancer Gene-Expression Miner v4.0 database and ONCOMINE databases, revealed a significant association between PSA expression and tumor grade (P = 0.0001), breast cancer subtype (P < 0.0001), in addition to early-stage disease presented as smaller tumor size and absence of LN involvement. The same trend confirmed with our patient cohort. Moreover, our analysis using KM plotter (4000 breast cancer samples) showed a significant association between higher PSA mRNA levels and favorable patient outcomes presented as prolonged relapse-free survival (RFS) (P < 0.0001). Conclusions: Our results clearly demonstrate the possibility of using tissue mRNA and protein levels of PSA as a marker to identify patients with a favorable outcome and lower risk of tumor recurrence. Our results also highlight the need for more efforts to investigate the biological role of PSA in breast cancer.

Effects of carboplatin combined with paclitaxel-based intraperitoneal hyperthermic perfusion chemotherapy on serum levels of HE4 and DJ-1 in patients with advanced recurrent ovarian cancer.

Objective:To analyze the effects of carboplatin combined with paclitaxel-based intraperitoneal hyperthermic perfusion chemotherapy (IPCH) on serum levels of human epididymis protein 4 (HE4) and mitogen-dependent oncogene-1 (DJ-1) in patients with advanced recurrent ovarian cancer (OC).Methods:From July 2019 to July 2020, patients with advanced recurrent OC (n=92) treated in Affiliated Hospital of Hebei Engineering University were selected as study subjects. According to the random number table method, patients were divided into control group and observation group. Patients in the control group were treated with carboplatin combined with paclitaxel-based intravenous chemotherapy, and patients in the observation group were treated with carboplatin combined with paclitaxel-based IPCH. The therapeutic effects, serum levels of HE4, DJ-1 and human kallikrein 10 (HK-10), peripheral blood immune indexes and adverse reactions of patients were compared between the two groups.Results:The response rate of the observation group was significantly higher than that of the control group (p<0.05); after treatment, the indexes of HE4, DJ-1 and HK-10 in the two groups were significantly decreased, while the indexes of CD3+CD4+, CD3+CD56+ and CD3+CD4+/CD3+CD8+ were significantly increased; moreover, significantly lower indexes of HE4, DJ-1 and HK-10 and significantly higher indexes of CD3+CD4+, CD3+CD56+ and CD3+CD4+/CD3+CD8+ were found in the observation group when compared with the control group (p<0.05). The severity of myelosuppression, nausea and vomiting in the observation group was significantly lower than that in the control group, and the total tumor metastasis rate in the observation group was significantly lower than that in the control group (p<0.05).Conclusions:Carboplatin combined with paclitaxel IPCH had obvious inhibitory effects on HE4, DJ-1 and other serum tumor markers in patients with advanced recurrent OC, with a more prominent clinical effect, and could further significantly reduce the risk of adverse reactions and metastasis.

Human Prothrombin Variants with Modifications in the Active Site S4 Subpocket Demonstrate Resistance to Dabigatran

Chymotrypsin-like serine proteases are hallmarked by a protease domain comprising the catalytic triad residues His57, Asp102, and Ser195 (chymotrypsinogen numbering) situated in the active site cleft. While the catalytic triad in conjunction with the oxyanion hole residues regulate substrate cleavage, the active site subpockets (S1-4) control substrate recognition and binding. The high structural homology of the serine protease domains allows for analogous strategies in drug design, which is underscored by the direct oral anticoagulants (DOACs) for the prophylactic management of stroke in atrial fibrillation and prevention and treatment of venous thrombosis. DOACs inhibit coagulation serine proteases by reversibly engaging the active site with high affinity. To expand the repertoire of DOAC-specific reversal agents we have previously successfully modified the S4 active site subpocket of human factor Xa to prevent DOAC binding while preserving catalytic activity [Verhoef 2017 Nature Commun.]. To explore whether an analogous strategy can be applied to create DOAC resistance in the serine protease thrombin, specific substitutions or sequences in or around the dabigatran-binding S4 subsite derived from naturally occurring serine proteases or plasma proteins were introduced in prothrombin.A panel of prothrombin variants was generated and transfected into HEK293 cells to allow for stable protein expression. In some of the generated prothrombin variants comprising insertions in amino acid sequence 91-99 that is directly adjacent to the S4 subsite protein expression was severely impaired. This indicates that exchange of any surface-exposed serine protease or plasma protein region into the prothrombin protease domain is not necessarily compatible with protein expression. In contrast, exchange of the human prothrombin 91-99 sequence for that of human kallikrein 3 or targeted amino acid replacement of S4 subsite residue Ile174 resulted in prothrombin protein expression levels similar to wild-type prothrombin.Following expression, prothrombin variants were purified to homogeneity using the CaptureSelect tm affinity matrix that selects for fully gamma-carboxylated prothrombin. The specific prothrombin clotting activity analyses of the purified prothrombin variants KL3 (0.7 ± 0.2 U/mg), I174A (0.8 ± 0.2 U/mg), and I174F (0.8 ± 0.3 U/mg) demonstrated an overall ~10-fold reduced specific activity relative to wild-type prothrombin (7.5 ± 0.1 U/mg). As such, modification of the S4 subsite likely interferes with the binding and subsequent conversion of fibrinogen by thrombin. To determine whether the prothrombin variants supported tissue factor-initiated thrombin formation in human plasma, prothrombin-deficient plasma was supplemented with increasing plasma concentrations of prothrombin variant (90-180 ug/mL). Consistent with their reduced specific clotting activity, 180 ug/mL prothrombin variant was required to obtain substantial thrombin generation but with reduced thrombin generation parameters (peak thrombin, ETP) relative to supplementation with plasma concentrations of wild-type prothrombin (90 ug/mL). This calibrated automated thrombin generation assay set-up was used to assess the DOAC-resistance of the prothrombin variants. While thrombin formation reached half-maximum inhibition at 532 ± 58 nM dabigatran in wild-type prothrombin-supplemented plasma, addition of the prothrombin variants displayed a ~2-fold reduced sensitivity to dabigatran inhibition (IC50: 1186 ± 136 nM prothrombin-KL3; 851 ± 97 nM prothrombin-I174F; 772 ± 80 nM prothrombin-I174A). This demonstrates that the S4 subsite-modified prothrombin variants are able to support thrombin generation in the presence of physiological plasma concentrations of inhibitor.Collectively, our findings indicate that human prothrombin variants comprising a single point mutation at position Ile174 in the S4 subsite or at a region directly adjacent to the S4 subsite are able to generate thrombin in plasma inhibited by dabigatran. Hence, serine proteases with S4 subpocket modifications have the potential to bypass DOAC therapy and could provide a generic strategy in the development of novel DOAC-bypassing agents. [Display omitted] DisclosuresReitsma: VarmX. B.V.: Current Employment, Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company, Patents & Royalties. Verhoef: VarmX. B.V.: Current Employment, Current holder of individual stocks in a privately-held company. Bos: VarmX B.V.: Research Funding; uniQure Biopharma B.V.: Research Funding.

Early prediction of prostate cancer biochemical recurrence and identification of disease persistence using PSA isoforms and human kallikrein-2.

The role of isoforms of prostate specific antigen (PSA) and other kallikrein-related markers in early detection of biochemical recurrence (BCR) after radical prostatectomy (RP) is not well known and serum PSA is currently used in preoperative risk nomograms. The aim of this research was to study pre- and early postoperative levels of important PSA isoforms and human kallikrein-2 to determine their ability to predict BCR and identify disease persistence (DP). This study included 128 consecutive patients who underwent RP for clinically localized prostate cancer. PSA, fPSA, %fPSA, [-2]proPSA, PHI and hK2 were measured preoperatively, at 1 and 3 months after RP. We determined the ability of these markers to predict BCR and identify DP. The DP and BCR rate were 11.7%and 20.3%respectively and the median follow up was 64 months (range 3-76 months). Preoperatively, the independent predictors of BCR were PSA (p-value 0.029), [-2]proPSA (p-value 0.002) and PHI (p-value 0.0003). Post-RP, PSA was the single marker correlating with BCR, both at one (p-value 0.0047) and 3 months (p-value 0.0004). PSA, fPSA, [-2]proPSA and PHI significantly correlated to DP at 1 and 3 months post-RP (p-value < 0.05), although PSA had the most significant existing correlation (p-value < 0.0001). [-2]proPSA and PHI are preoperative predictors of BCR and DP that outperform the currently used serum PSA. At the early postoperative period there is no additional benefit of the other markers tested.