Cytotoxic activity and cell specificity of a novel LHRH peptide drug conjugate, D-Cys6-LHRH vedotin, against ovarian cancer cell lines.

Ovarian cancer is the most deadly female gynaecological malignancy in developed countries and new treatments are urgently needed. The luteinising hormone releasing hormone (LHRH) peptide drug conjugate Zoptarelin doxorubicin is one such potential new drug modality that entered clinical trials for treating LHRH receptor-positive gynaecological cancers. However, development stopped after disappointing Phase 3 results in 2017. We believe the lack of efficacy was due to linker instability and payload potency. In this work, we replaced its linker-toxin with vedotin (MC-VC-PABC-MMAE), yielding the novel peptide drug conjugate D-Cys6-LHRH vedotin. A GI50 and cell specificity comparison against cancerous and non-cancerous ovarian cell lines showed significantly superior bioactivity and selectivity over Zoptarelin doxorubicin (GI50 4 vs. 453 nM) and other chemotherapeutic drugs used for treating ovarian cancers. Our results suggest D-Cys6-LHRH vedotin can potentially be used as a treatment for ovarian cancer.

A Patent Review on SARS Coronavirus Papain-Like Protease (PLpro ) Inhibitors.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic is an unprecedented global health emergency causing more than 6.6 million fatalities by 31 December 2022. So far, only three antiviral drugs have been granted emergency use authorisation or approved by the FDA. The SARS-CoV-2 papain-like protease (PLpro ) is deemed an attractive drug target as it plays an essential role in viral polyprotein processing and pathogenesis although no inhibitors have yet been approved. This patent review discusses coronavirus PLpro inhibitors reported in patents published between 1 January 2003 to 2 March 2023, giving an overview on the inhibitors that have generated commercial interest, especially amongst drug companies.

Novel PSMA-Targeting Radionuclide Peptidomimetics for Treating Prostate Cancer.

Prostate cancer is the third-most commonly diagnosed cancer and is one of the leading causes of cancer-related deaths in men worldwide. Although an armamentarium of approved drugs exists, treatment options become severely limited when resistance develops against last-line taxane chemotherapeutics. In March 2022, the FDA approved a first-in-class targeted radionuclide therapy, lutetium Lu 177 vipivotide tetraxetan (Pluvicto), for treating metastatic castration-resistant prostate cancer. The drug constitutes a prostate-specific membrane antigen-targeting peptidomimetic moiety conjugated to a radionuclide chelator via a linker. This Patent Highlight reveals the structure-activity relationship of key compounds against prostate cancer cells.

A Patent Review on FDA-Approved Antibody-Drug Conjugates, Their Linkers and Drug Payloads.

Antibody-drug conjugates (ADCs) have emerged as a promising class of biologics since the first approval of Gemtuzumab ozogamicin in 2000. Compared to small molecule drugs, ADCs are structurally much more complex as they comprise of an antibody conjugated to cytotoxic payloads by specially-designed linkers. Correspondingly, the ADC patent landscape is also much more complex. This review collates and discusses the patents protecting ADCs approved by the FDA up to 31 December 2021, with particular emphasis on their linker and cytotoxin payload technologies.

A Patent Review on SARS Coronavirus Main Protease (3CLpro ) Inhibitors.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic is an unprecedented global health emergency causing more than 4.2 million fatalities as of 30 July 2021. Only three antiviral therapies have been approved or granted emergency use authorization by the FDA. The SARS-CoV-2 3CL protease (3CLpro ) is deemed an attractive drug target as it plays an essential role in viral polyprotein processing and pathogenesis, although no inhibitors have been approved. This patent review discusses SARS coronavirus 3CLpro inhibitors that have been filed up to 30 July 2021, giving an overview on the types of inhibitors that have generated commercial interest, especially amongst drug companies. Insights into the common structural motifs required for active site binding is also discussed.

A head-to-head comparison of the inhibitory activities of 15 peptidomimetic SARS-CoV-2 3CLpro inhibitors.

The COVID-19 pandemic caused by SARS-CoV-2 has created an unprecedented global health emergency. As of July 2021, only three antiviral therapies have been approved by the FDA for treating infected patients, highlighting the urgent need for more antiviral drugs. The SARS-CoV-2 3CL protease (3CLpro) is deemed an attractive drug target due to its essential role in viral polyprotein processing and pathogenesis. Indeed, a number of peptidomimetic 3CLpro inhibitors armed with electrophilic warheads have been reported by various research groups that can potentially be developed for treating COVID-19. However, it is currently impossible to compare their relative potencies due to the different assays employed. To solve this, we conducted a head-to-head comparison of fifteen reported peptidomimetic inhibitors in a standard FRET-based SARS-CoV-2 3CLpro inhibition assay to compare and identify potent inhibitors for development. Inhibitor design and the suitability of various warheads are also discussed.

Targeting cancer addiction for SALL4 by shifting its transcriptome with a pharmacologic peptide.

Sal-like 4 (SALL4) is a nuclear factor central to the maintenance of stem cell pluripotency and is a key component in hepatocellular carcinoma, a malignancy with no effective treatment. In cancer cells, SALL4 associates with nucleosome remodeling deacetylase (NuRD) to silence tumor-suppressor genes, such as PTEN. Here, we determined the crystal structure of an amino-terminal peptide of SALL4(1-12) complexed to RBBp4, the chaperone subunit of NuRD, at 2.7 Å, and subsequent design of a potent therapeutic SALL4 peptide (FFW) capable of antagonizing the SALL4-NURD interaction using systematic truncation and amino acid substitution studies. FFW peptide disruption of the SALL4-NuRD complex resulted in unidirectional up-regulation of transcripts, turning SALL4 from a dual transcription repressor-activator mode to singular transcription activator mode. We demonstrate that FFW has a target affinity of 23 nM, and displays significant antitumor effects, inhibiting tumor growth by 85% in xenograft mouse models. Using transcriptome and survival analysis, we discovered that the peptide inhibits the transcription-repressor function of SALL4 and causes massive up-regulation of transcripts that are beneficial to patient survival. This study supports the SALL4-NuRD complex as a drug target and FFW as a viable drug candidate, showcasing an effective strategy to accurately target oncogenes previously considered undruggable.

Patients with Peritoneal Carcinomatosis from Gastric Cancer Treated with Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy: Is Cure a Possibility?

BACKGROUND: Peritoneal carcinomatosis is an increasingly common finding in gastric carcinoma. Previously, patients were treated as terminal, and median survival was poor. The use of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) in this context is still highly debatable. OBJECTIVE: The aim of this study was to evaluate the long-term outcomes associated with CRS and HIPEC, and define prognostic factors for cure, if possible. PATIENTS AND METHODS: All patients with gastric carcinomatosis from five French institutions who underwent combined complete CRS and HIPEC and had a minimum follow-up of 5 years were included in this study. Cure was defined as a disease-free interval of more than 5 years from the last treatment until the last follow-up. RESULTS: Of the 81 patients who underwent CRS and HIPEC from 1989 to 2009, 59 had a completeness of cytoreduction score (CCS) of 0 (complete macroscopic resection), and the median Peritoneal Cancer Index (PCI) score was 6. Mitomycin C was the most commonly used drug during HIPEC (88 %). The 5-year overall survival (OS) rate was 18 %, with nine patients still disease-free at 5 years, for a cure rate of 11 %. All 'cured' patients had a PCI score below 7 and a CCS of 0. Factors associated with improved OS on multivariate analysis were synchronous resection (p = 0.02), a lower PCI score (p = 0.12), and the CCS (p = 0.09). CONCLUSION: The cure rate of 11 % for patients with gastric carcinomatosis who are deemed terminal emphasizes that CRS and HIPEC should be considered in highly selected patients (low disease extent and complete CRS).

Peptidomimetic ethyl propenoate covalent inhibitors of the enterovirus 71 3C protease: a P2-P4 study.

Enterovirus 71 (EV71) is a highly infectious pathogen primarily responsible for Hand, Foot, and Mouth Disease, particularly among children. Currently, no approved antiviral drug has been developed against this disease. The EV71 3C protease is deemed an attractive drug target due to its crucial role in viral polyprotein processing. Rupintrivir, a peptide-based inhibitor originally developed to target the human rhinovirus 3C protease, was found to inhibit the EV71 3C protease. In this communication, we report the inhibitory activities of 30 Rupintrivir analogs against the EV71 3C protease. The most potent inhibitor, containing a P2 ring-constrained phenylalanine analog (compound 9), was found to be two-fold more potent than Rupintrivir (IC50 value 3.4 ± 0.4 versus 7.3 ± 0.8 µM). Our findings suggest that employing geometrically constrained residues in peptide-based protease inhibitors can potentially enhance their inhibitory activities.

Antiviral activities of 15 dengue NS2B-NS3 protease inhibitors using a human cell-based viral quantification assay.

The dengue virus is a mosquito-borne pathogen responsible for an estimated 50-100 million human dengue infections annually. There are currently no approved drugs against this disease, resulting in a major unmet clinical need. The dengue viral NS2B-NS3 protease has been identified as a plausible drug target due to its involvement in viral replication in mammalian host cells. In the past decade, at least 20 dengue NS2B-NS3 protease inhibitors have been reported in the literature with a range of inhibitory activities in protease assays. However, such assays do not shed light on an inhibitor's ability to penetrate human cell membranes where the viral protease resides. In this study, we investigated the antiviral activities of 15 small-molecule and peptide-based NS2B-NS3 inhibitors on dengue serotype 2-infected HuH-7 human hepatocarcinoma cells. Experimental results revealed anthraquinone ARDP0006 (compound 5) to be the most potent inhibitor which reduced dengue viral titer by more than 1 log PFU/mL at 1 µM in our cell-based assays involving HuH-7 and K562 cell lines, suggesting that its scaffold could serve as a lead for further medicinal chemistry studies. Compound 5 was also found to be non-cytotoxic at 1 µM over 3 days incubation on HuH-7 cells using the Alamar Blue cellular toxicity assay.

Quality of life in patients with peritoneal surface malignancies after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy.

BACKGROUND: An increasing number of patients are presenting with peritoneal carcinomatosis and more centers are performing cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). While morbidity and mortality are shown to be acceptable, quality of life after surgery should be assessed. METHODS: 63 patients who had CRS and HIPEC from 2001 to 2012 and who were still alive and on follow up were included. The EORTC-QLQ-C30 was administered to the patients. RESULTS: Median age was 53 years (14-71). 44% had ovarian primaries, 21% had appendicael primaries and 19% had colorectal primaries. Median follow-up was 1.08 years (0.06-9.8). The median time from surgery to the questionnaire was 1.3 years (0.24-10.18). There was no statistical difference in scores when comparing by age, gender, recurrence, gender, PCI score, presence of a complication and type of primary cancer. Scores were highest less than 6 months after surgery, dropped subsequently but rose again after 2 years. Our patients had better scores compared to a control group of outpatient cancer patients at our institution as well as the reference EORTC group. CONCLUSIONS: In keeping with previous quality of life studies done for CRS and HIPEC patients, we have shown that our patients can achieve a good quality of life after CRS and HIPEC even with recurrent disease.

A P2 and P3 substrate specificity comparison between the Murray Valley encephalitis and West Nile virus NS2B/NS3 protease using C-terminal agmatine dipeptides.

The Murray Valley encephalitis virus (MVEV) and the West Nile virus (WNV) are mosquito-borne single-stranded RNA Flaviviruses responsible for many cases of viral encephalitis and deaths worldwide. The former is endemic in north Australia and Papua New Guinea while the latter has spread to different parts of the world and was responsible for a recent North American outbreak in 2012, resulting in 243 fatalities. There is currently no approved vaccines or drugs against MVEV and WNV viral infections. A plausible drug target is the viral non-structural NS2B/NS3 protease due to its role in viral replication. This trypsin-like serine protease recognizes and cleaves viral polyproteins at the C-terminal end of an arginine residue, opening an avenue for the development of peptide-based antivirals. This communication compares the P2 and P3 residue preferences of the MVEV and WNV NS2B/NS3 proteases using a series of C-terminal agmatine dipeptides. Our results revealed that both viral enzymes were highly specific toward lysines at the P2 and P3 positions, suggesting that a peptidomimetic viral protease inhibitor developed against one virus should also be active against the other.

Stabilizing the eIF4G1 α-helix increases its binding affinity with eIF4E: implications for peptidomimetic design strategies.

Eukaryotic initiation factor (eIF)4E is overexpressed in many types of cancer such as breast, head and neck, and lung. A consequence of increased levels of eIF4E is the preferential translation of pro-tumorigenic proteins such as c-Myc, cyclin D1, and vascular endothelial growth factor. Inhibition of eIF4E is therefore a potential therapeutic target for human cancers. A novel peptide based on the eIF4E-binding peptide eIF4G1, where the α-helix was stabilized by the inclusion of α-helix inducers as shown by CD measurements, was synthesized. The helically stabilized peptide binds with an apparent K(d) of 9.43±2.57 nM, which is ∼15.7-fold more potent than the template peptide from which it is designed. The helically stabilized peptide showed significant biological activity at a concentration of 400 µM, unlike the naturally occurring eIFG1 peptide when measured in cell-based cap-dependent translational reporter and WST-1 (4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate) assays. Fusion of the template peptide and the stabilized peptide to the cell-penetrating peptide TAT produced more active but equally potent inhibitors of cap-dependent translation in cell lines. They also equally disrupted cell metabolism as measured in a WST-1 assay. Propidium iodide staining revealed that the TAT-fused, helically stabilized peptide caused more cell death than the TAT-fused eIF4G1 template peptide with substantial decreases in the G1 and G2 cell populations. Annexin-staining experiments also indicated that the TAT-fused eIF4G1 derivative peptides caused cell death by apoptosis. The results presented should offer further insight into peptidomimetics development for eIF4E.

Adenocarcinoma of the anal transitional zone after double stapled ileal pouch-anal anastomosis for ulcerative colitis.

The development of adenocarcinoma in the anal transitional zone, after restorative proctocolectomy for ulcerative colitis, is rare. We report the first Asian and sixth known case. A 41-year-old Indian lady had a long standing history of ulcerative colitis. Restorative proctocolectomy and stapled ileal pouch-anal anastomosis without mucosectomy was performed. She remained asymptomatic until 3 years later when she complained of discomfort on defecation. A poorly differentiated adenocarcinoma in the anal transition zone was diagnosed and she subsequently underwent an abdomino-perineal resection. The previously reported cases in the literature are reviewed. We also discuss the suggested surveillance for high-risk patients who have undergone an ileal-anal pouch anastomosis.