Search

Highly symmetric ligands can bind in multiple identical binding modes. The improved binding affinity arising from higher entropy was elucidated in this work.

Background Immune checkpoint blockade (ICB) results in radiologic tumour response dynamics that differ from chemotherapy efficacy measures and require an early signal of clinical utility. Methods Previously untreated, unresectable microsatellite-stable (MSS)/mismatch repair-proficient (pMMR) colorectal cancer (CRC) patients were randomly assigned to the oxaliplatin-based Nordic FLOX regimen (control arm) or repeat sequential two FLOX cycles and two ICB cycles (experimental arm). The radiologic response was assessed every 8 weeks. In this post hoc analysis, we explored early target lesion (TL) dynamics as indicator of ICB responsiveness. Progression-free survival (PFS) was the primary endpoint. Results Using a landmark analysis approach, we categorised experimental-arm patients into ≥10% (N = 19) or N = 16) TL reduction at the first post-baseline response assessment. Median PFS for the groups was 16.0 (95% confidence interval (CI), 12.3–19.7) and 3.9 months (95% CI, 2.3–5.5), respectively, superior and inferior (both P N = 31). Conclusions Radiologic TL reduction of ≥10% at the first post-baseline response assessment identified patients with ICB-responsive metastatic MSS/pMMR-CRC. This pragmatic measure may be used to monitor patients in investigational ICB schedules, enabling early treatment adaptation for unresponsive cases. Trial registration ClinicalTrials.gov number, NCT03388190 (02/01/2018).

Covalent peptidomimetic protease inhibitors have gained a lot of attention in drug development in recent years. They are designed to covalently bind the catalytically active amino acids through electrophilic groups called warheads. Covalent inhibition has an advantage in terms of pharmacodynamic properties but can also bear toxicity risks due to non-selective off-target protein binding. Therefore, the right combination of a reactive warhead with a well-suited peptidomimetic sequence is of great importance. Herein, the selectivities of well-known warheads combined with peptidomimetic sequences suited for five different proteases were investigated, highlighting the impact of both structure parts (warhead and peptidomimetic sequence) for affinity and selectivity. Molecular docking gave insights into the predicted binding modes of the inhibitors inside the binding pockets of the different enzymes. Moreover, the warheads were investigated by NMR and LC-MS reactivity assays against serine/threonine and cysteine nucleophile models, as well as by quantum mechanics simulations.

PDF file - 2567KB

Purpose: We report two clinical trials in non–small cell lung cancer (NSCLC) patients evaluating immune response, toxicity, and clinical outcome after vaccination with the telomerase peptide GV1001: a phase II trial (CTN-2006) in patients vaccinated after chemoradiotherapy and an 8-year update on a previously reported phase I/II trial (CTN-2000).Experimental Design: CTN-2006: 23 inoperable stage III patients received radiotherapy (2 Gy × 30) and weekly docetaxel (20 mg/m2), followed by GV1001 vaccination. CTN-2000: 26 patients were vaccinated with two telomerase peptides (GV1001 and I540). The immune responses were evaluated by T-cell proliferation and cytokine assays.Results: CTN-2006 trial: a GV1001-specific immune response developed in 16/20 evaluable patients. Long-term immunomonitoring showed persisting responses in 13 subjects. Serious adverse events were not observed. Immune responders recorded a median PFS of 371 days, compared with 182 days for nonresponders (P = 0.20). CTN-2000 trial update: 13/24 evaluable subjects developed a GV1001 response. The immune responders achieved increased survival compared with nonresponders (median 19 months vs. 3.5 months; P < 0.001). Follow-up of four long-time survivors showed that they all harbored durable GV1001-specific T-cell memory responses and IFNγhigh/IL-10low/IL-4low cytokine profiles. Two patients are free of disease after 108 and 93 months, respectively.Conclusions: Vaccination with GV1001 is well tolerated, immunizes the majority of NSCLC patients and establishes durable T-cell memory. The considerable immune response rate and low toxicity in the phase II trial support the concept of combining chemoradiotherapy with vaccination. The survival advantage observed for immune responders warrants a randomized trial. Clin Cancer Res; 17(21); 6847–57. ©2011 AACR.

PDF file - 17KB

PDF file - 2417KB

PDF file - 16KB

Abstract: Due to its fast international spread and substantial mortality, the coronavirus disease COVID-19 evolved to a global threat. Since there is currently no causative drug against this viral infection available, science is striving for new drugs and other approaches to treat the new disease. Studies have shown that the cell entry of coronaviruses into host cells takes place through the binding of the viral spike (S) protein to cell receptors. Priming of the S protein occurs via hydrolysis by different host proteases. The inhibition of these proteases could impair the processing of the S protein, thereby affecting the interaction with the host-cell receptors and preventing virus cell entry. Hence, inhibition of these proteases could be a promising strategy for treatment against SARSCoV- 2. In this review, we discuss the current state of the art of developing inhibitors against the entry proteases furin, the transmembrane serine protease type-II (TMPRSS2), trypsin, and cathepsin L.

High-grade (HG) gastroenteropancreatic (GEP) neuroendocrine neoplasms (NEN) are rare but have a very poor prognosis and represent a severely understudied class of tumours. Molecular data for HG GEP-NEN are limited, and treatment strategies for the carcinoma subgroup (HG GEP-NEC) are extrapolated from small-cell lung cancer (SCLC). After pathological re-evaluation, we analysed DNA from tumours and matched blood samples from 181 HG GEP-NEN patients; 152 neuroendocrine carcinomas (NEC) and 29 neuroendocrine tumours (NET G3). Based on the sequencing of 360 cancer-related genes, we assessed mutations and copy number alterations (CNA). For NEC, frequently mutated genes were TP53 (64%), APC (28%), KRAS (22%) and BRAF (20%). RB1 was only mutated in 14%, but CNAs affecting RB1 were seen in 34%. Other frequent copy number losses were ARID1A (35%), ESR1 (25%) and ATM (31%). Frequent amplifications/gains were found in MYC (51%) and KDM5A (45%). While these molecular features had limited similarities with SCLC, we found potentially targetable alterations in 66% of the NEC samples. Mutations and CNA varied according to primary tumour site with BRAF mutations mainly seen in colon (49%), and FBXW7 mutations mainly seen in rectal cancers (25%). Eight out of 152 (5.3%) NEC were microsatellite instable (MSI). NET G3 had frequent mutations in MEN1 (21%), ATRX (17%), DAXX, SETD2 and TP53 (each 14%). We show molecular differences in HG GEP-NEN, related to morphological differentiation and site of origin. Limited similarities to SCLC and a high fraction of targetable alterations indicate a high potential for better-personalized treatments.

PURPOSE Gastroenteropancreatic neuroendocrine carcinomas (GEP-NEC) are rare and have a poor prognosis. Most GEP-NEC are diagnosed with metastatic disease, with only minor biopsies available for molecular diagnostics. We assessed the applicability of liquid biopsies for molecular profiling of GEP-NEC. MATERIALS AND METHODS We performed massive parallel sequencing of 76 cancer-related genes in circulating tumor DNA from 50 patients with advanced GEP-NEC and compared findings to previous analyses of solid tumor biopsies from the same patients. Plasma samples were collected before therapy, and the median time span between blood and tissue sampling was 25 days. RESULTS We detected 178 somatic mutations in the liquid biopsies, 127 (71%) were also detected in the solid biopsies, whereas 51 (29%) were unique to the liquid biopsies. In the same 76 genes, we previously detected 199 somatic mutations (single nucleotide variants) in solid biopsies, of which 127 (64%) were also now detected in liquid biopsies. In exploratory subgroup assessments, concordance was higher in patients with liver metastases ( P = 1.5 × 10–5) and increasing with level of liver involvement ( P = 1.2 × 10–4). The concordance was similar between GEP-NEC with different primary sites, except being lower in esophageal cases ( P = .001). Concordance was not associated with tumor mutation burden. Tumor tissue mutations also detected in liquid biopsies was lower for MSI (40%) versus MSS tumors (70%; P = 7.8 × 10–4). We identified potentially targetable mutations in plasma of 26 (52%) of patients with GEP-NEC; nine patients (18%) had potentially targetable mutation detected only in liquid biopsies. CONCLUSION Liquid biopsy analyses may be an applicable alternative to solid biopsies in GEP-NEC. Liquid biopsies may add additional mutations compared with tumor biopsies alone and could be useful for biomarker assessment in clinical trials for these patients.

Cyclization of small molecules is a widely applied strategy in drug design for ligand optimization to improve affinity, as it eliminates the putative need for structural preorganization of the ligand before binding, or to improve pharmacokinetic properties. In this work, we provide a deeper insight into the binding thermodynamics of a macrocyclic Zika virus NS2B/NS3 protease inhibitor and its linear analogs. Characterization of the thermodynamic binding profiles by isothermal titration calorimetry experiments revealed an unfavorable entropy of the macrocycle compared to the open linear reference ligands. Molecular dynamic simulations and X-ray crystal structure analysis indicated only minor benefits from macrocyclization to fixate a favorable conformation, while linear ligands retained some flexibility even in the protein-bound complex structure, possibly explaining the initially surprising effect of a higher entropic penalty for the macrocyclic ligand.

Introduction: \ud The presence of preoperative systemic inflammatory response (SIR) is an established negative prognostic factor for patients diagnosed with colorectal cancer (CRC). C-reactive protein (CRP) is known to be implicated in detrimental immune responses. The biological differences between right-sided and left-sided CRC are gaining increasing attention. Our aim was to analyse the prognostic value of CRP and explore the association between tumour location and SIR.\ud \ud Material and methods: \ud A total of 2059 patients treated for stage I–III CRC, identified from the prospectively sampled ScotScan Collaborative dataset, were included. The clinical and prognostic value of five CRP levels (100 mg/l) were examined. Additionally, the relationship between SIR and tumour location was explored.\ud \ud Results: \ud Increasing levels of CRP were associated with impaired overall and cancer-specific outcome. Presence of SIR was independently associated with right-sided tumour location (p

Rhodesain is a major cysteine protease of Trypanosoma brucei rhodesiense, a pathogen causing Human African Trypanosomiasis, and a validated drug target. Recently, we reported the development of α-halovinylsulfones as a new class of covalent reversible cysteine protease inhibitors. Here, α-fluorovinylsulfones/-sulfonates were optimized for rhodesain based on molecular modeling approaches. 2d, the most potent and selective inhibitor in the series, shows a single-digit nanomolar affinity and high selectivity toward mammalian cathepsins B and L. Enzymatic dilution assays and MS experiments indicate that 2d is a slow-tight binder (Ki = 3 nM). Furthermore, the nonfluorinated 2d-(H) shows favorable metabolism and biodistribution by accumulation in mice brain tissue after intraperitoneal and oral administration. The highest antitrypanosomal activity was observed for inhibitors with an N-terminal 2,3-dihydrobenzo[b][1,4]dioxine group and a 4-Me-Phe residue in P2 (2e/4e) with nanomolar EC50 values (0.14/0.80 μM). The different mechanisms of reversible and irreversible inhibitors were explained using QM/MM calculations and MD simulations.

Selective manipulation of the epitranscriptome could be beneficial for the treatment of cancer and also broaden the understanding of epigenetic inheritance. Inhibitors of the tRNA methyltransferase DNMT2, the enzyme catalyzing the

WNT/β-catenin signaling endows cancer cells with proliferative capacity and immune-evasive functions that impair anti-cancer immunosurveillance by conventional, cytoxtoic T cells. However, the impact of dysregulated WNT signalling on unconventional, tissue-resident T cells, specifically in colon cancer is unknown. Here, we show that cancer cells in Apc-mutant mouse models escape immunosurveillance from gut-resident intraepithelial lymphocytes (IELs) expressing γδ T cell receptors (γδTCRs). Analysis of late-stage tumors from mice and humans revealed that γδIELs are largely absent from the tumor microenvironment, and that butyrophilin-like (BTNL) molecules, which can critically regulate γδIEL through direct γδTCR-interactions, are also downregulated. We could attribute this to β-catenin stabilization, which rapidly decreased expression of the transcription factors, HNF4A and HNF4G, that we found to bind promoter regions of Btnl genes, thereby driving their expression in normal gut epithelial cells. Indeed, inhibition of β-catenin signaling restored Btnl1 gene expression and γδ T cell infiltration into tumors. These observations highlight an immune-evasion mechanism specific to WNT-driven colon cancer cells that disrupts γδIEL immunosurveillance and furthers cancer progression.

Background: Novel treatments of neuropathic pain are urgently needed. Rapid relief of neuropathic cancer pain in patients treated with epidermal growth factor receptor (EGFR) inhibitors have been reported. Experiments in rodent models confirm the pain relief and reveal novel mechanisms critically involving the EGFR. Clinical pain research is complicated and patients with advanced cancer are heterogeneous, often with complex, deteriorating clinical pictures, hampering feasibility of drug-trial procedures. Actual case: Prospective case series exploring the EGFR inhibition/neuropathic cancer pain association in order to inform planning clinical trials. Possible courses of action: Symptom assessment method was tailored to what was ethical, feasible, and clinically relevant for each patient. Formulation of a plan: Patients with neuropathic cancer pain treated off-label with the monoclonal antibody panitumumab were studied to assess feasibility of different measurement tools. Outcome: Fourteen of 20 patients (70%) experienced clinically significant pain relief. There was good concordance in patient and physician-reported outcomes. Lessons: Results support panitumumab’s potential to be of significant benefit to patients with refractory neuropathic cancer pain. Findings also reinforce the difficulty of using conventional drug trial endpoints and designs in this population. View: Innovative research methods must be considered for much needed pivotal trials.

A fluorescent analogue of abscisic acid has been prepared by combining (S)‐abscisic acid (ABA) with nitrobenzoxadiazole (NBD) fluorophore using ethanol amine as a linker. Isomerization of the double bond at the side chain of abscisic acid happened during the synthesis. The resulting fluorophore analogues derived from both isomeric compounds entered cells suggesting a wide applicability of the ABA‐NBD conjugates as fluorescent probes to study ABA mechanism of action. The functional properties of the isomeric ABA‐NBD conjugates were tested in vitro, by measuring TNFα expression and nitrite concentration in LPS‐stimulated macrophages and compared with their non‐fluorescent ABA isomers. Rationalization of the results is given as supported by docking studies of the compounds with LANCL2 and PPARγ targets.

In many solid tumors, increased upregulation of transmembrane serine proteases (TTSPs) leads to an overactivation of growth factors, which promotes tumor progression. Here, we have used a combinatorial methodology to develop high-affinity tetrapeptidic inhibitors. A previous virtual screening of 8000 peptide combinations against the crystal structure of the TTSP hepsin identified a series of recognition sequences, customized for the non-prime substrate binding (P) sites of this serine protease. A combination of the top recognition sequences with an electrophilic warhead resulted in highly potent inhibitors with good selectivity against coagulation proteases factor Xa and thrombin. Structure-activity relationships of two selected compounds were further elucidated by investigation of their stability in biological fluids as well as the influence of the warhead and truncated inhibitors on the inhibitory potency. Overall, this methodology yielded compounds as selective inhibitors for potential cancer drug development, where hepsin is overexpressed.

Protease inhibitors represent a promising therapeutic option for the treatment of parasitic diseases such as malaria and human African trypanosomiasis. Falcitidin was the first member of a new class of inhibitors of falcipain-2, a cysteine protease of the malaria parasite Plasmodium falciparum. Using a metabolomics dataset of 25 Chitinophaga strains for molecular networking enabled identification of over 30 natural analogues of falcitidin. Based on MS/MS spectra, they vary in their amino acid chain length, sequence, acyl residue, and C-terminal functionalization; therefore, they were grouped into the four falcitidin peptide families A-D. The isolation, characterization, and absolute structure elucidation of two falcitidin-related pentapeptide aldehyde analogues by extensive MS/MS spectrometry and NMR spectroscopy in combination with advanced Marfey’s analysis was in agreement with the in silico analysis of the corresponding biosynthetic gene cluster. Total synthesis of chosen pentapeptide analogues followed by in vitro testing against a panel of proteases revealed selective parasitic cysteine protease inhibition and, additionally, low-micromolar inhibition of α-chymotrypsin. The pentapeptides investigated here showed superior inhibitory activity compared to falcitidin.

Purpose: Most mCRC patients harbor MSS disease without inherent immunogenicity. The METIMMOX study (NCT03388190) explored an unconventional concept, that patients with previously untreated, unresectable abdominal metastases from MSS-CRC may achieve therapeutic efficacy from short-course oxaliplatin-based chemotherapy (FLOX) and sequential ICB (nivolumab). Among study patients who were assigned this highly experimental treatment, 15% obtained long-lasting complete response and more than a half met an early occurring radiologic signal of ICB responsiveness predicting significantly extended progression-free survival (PFS) compared to study control arm patients given standard FLOX chemotherapy [PMID: 36229579]. The aim of the present study was to verify if systemic tumor-defeating immunity had been invoked by the short-course FLOX treatment in the responding patients. The fms-related tyrosine kinase-3 ligand (Flt3L) is a circulating factor that reflects the direct cytotoxic effects of chemotherapy and also activates dendritic cells that present the shed tumor antigens to tumor-targeting T-cells. Procedures: Study patients were randomly assigned to the control arm of FLOX (oxaliplatin 85 mg/m2 on day 1 and bolus 5-fluorouracil 500 mg/m2 and folinic acid 100 mg on days 1 and 2) Q2W or the experimental arm of repeat sequential cycles of 2 FLOX Q2W and 2 nivolumab (240 mg) Q2W. Radiologic response assessment was done every 8 weeks with PFS as the primary endpoint. Patients were categorized into those with target lesion (TL) reduction of ≥10% or Results: For all subjects, median Flt3L was 103.8 pg/ml (range 24.6-306.1) at baseline and 162.4 pg/ml (range 53.3-503.8) at 4 weeks. For the experimental arm patients (n = 34), the higher 4-week Flt3L level, the deeper overall radiologic response (rho = -0.39, p = 0.022, Spearman correlation). The 4-week Flt3L level was higher in patients who obtained ≥10% TL reduction (n = 18; median 233.5 pg/ml, range 94.9-466.7) than in those who did not meet this 8-week predictive signal of extended PFS (n = 16; median 161.9 pg/ml, range 53.3-374.8; p = 0.022, Mann-Whitney U test). Selecting a 160 pg/ml cut-off, patients with 4-week Flt3L values above (n = 21) obtained longer PFS (median of 13.6 months, 95% CI 7.6-19.7) than those with serum values below (n = 13; median PFS of 5.9 months, 95% CI 2.4-9.3; p = 0.046, log-rank test). Conclusions: High circulating Flt3L after initial short-course FLOX chemotherapy, as a proxy of invoked tumor-defeating immunity, was associated with an early radiologic signal of ICB responsiveness and improved PFS in patients with MSS-mCRC. Citation Format: Sebastian Meltzer, Kjersti Flatmark, Anniken J. Fuglestad, Hanne M. Hamre, Christian Kersten, Eva Hofsli, Marianne G. Guren, Halfdan Sorbye, Anne Negård, Anne Hansen Ree. Systemic immune response invoked by short-course oxaliplatin-based chemotherapy (FLOX) for efficacy of sequential immune checkpoint blockade (ICB; nivolumab) in microsatellite-stable (MSS) metastatic colorectal cancer (mCRC) [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 3279.

Targeting RNA methyltransferases with small molecules as inhibitors or tool compounds is an emerging field of interest in epitranscriptomics and medicinal chemistry. For two challenging RNA methyltransferases that introduce the 5-methylcytosine (m5C) modification in different tRNAs, namely DNMT2 and NSUN6, an ultra-large commercially available chemical space was virtually screened by physicochemical property filtering, molecular docking, and clustering to identify new ligands for those enzymes. Novel chemotypes binding to DNMT2 and NSUN6 with affinities down to KD,app = 37 µM and KD,app = 12 µM, respectively, were identified using a microscale thermophoresis (MST) binding assay. These compounds represent the first molecules with a distinct structure from the cofactor SAM and have the potential to be developed into activity-based probes for these enzymes. Additionally, the challenges and strategies of chemical space docking screens with special emphasis on library focusing and diversification are discussed.

Ipilimumab was the first treatment that improved survival in advanced melanoma. Efficacy and toxicity in a real-world setting may differ from clinical trials, due to more liberal eligibility criteria and less intensive monitoring. Moreover, high costs and lack of biomarkers have raised cost-benefit concerns about ipilimumab in national healthcare systems and limited its use. Here, we report the prospective, interventional study, Ipi4 (NCT02068196), which aimed to investigate the toxicity and efficacy of ipilimumab in a real-world population with advanced melanoma. This national, multicentre, phase IV trial included 151 patients. Patients received ipilimumab 3 mg/kg intravenously and were followed for at least five years or until death. Treatment interruption or cessation occurred in 38%, most frequently due to disease progression (19%). Treatment-associated grade 3-4 toxicity was observed in 29% of patients, and immune-related toxicity in 56%. The overall response rate was 9%. Median overall survival was 12.1 months (95% CI: 8.3-15.9); and progression-free survival 2.7 months (95% CI: 2.6-2.8). After five years, 20% of patients were alive. In a landmark analysis from six months, improved survival was associated with objective response (HR 0.16, p = 0.001) and stable disease (HR 0.49, p = 0.005) compared to progressive disease. Poor performance status, elevated lactate dehydrogenase and C-reactive protein were identified as biomarkers. This prospective trial represents the longest reported follow-up of a real-world melanoma population treated with ipilimumab. Results indicate safety and efficacy comparable to phase III trials and suggest that the use of ipilimumab can be based on current cost-benefit estimates. This article is protected by copyright. All rights reserved.

Protease inhibitors represent a promising therapeutic option for the treatment of parasitic diseases such as malaria and human African trypanosomiasis. Falcitidin was the first member of a new class of inhibitors of falcipain-2, a cysteine protease of the malaria parasite Plasmodium falciparum. Using a metabolomics dataset of 25 Chitinophaga strains for molecular networking enabled identification of over 30 natural analogs of falcitidin. Based on MS/MS spectra, they vary in their amino acid chain length, sequence, acyl residue, and C-terminal functionalization; therefore, they were grouped into the four falcitidin peptide families A-D. The isolation, characterization and absolute structure elucidation of two falcitidin-related pentapeptide aldehyde analogs by extensive MS/MS spectrometry and NMR spectroscopy in combination with advanced Marfey’s analysis was in agreement with the in silico analysis of the corresponding biosynthetic gene cluster. Total synthesis of chosen pentapeptide analogs followed by in vitro testing against a panel of proteases revealed selective parasitic cysteine protease inhibition and additionally low-micromolar inhibition of α-chymotrypsin. The pentapeptides investigated here showed superior inhibitory activity compared to falcitidin.

The NS2B/NS3 serine proteases of the Zika and Dengue flaviviruses are attractive targets for the development of antiviral drugs. We report the synthesis and evaluation of a new, proline-based compound class that displays allosteric inhibition of both proteases. The structural features relevant for protease binding and inhibition were determined to establish them as new lead compounds for flaviviral inhibitors. Based on our structure-activity relationship studies, the molecules were further optimized, leading to inhibitors with submicromolar IC50 values and improved lipophilic ligand efficiency. The allosteric binding site in the proteases was probed using mutagenesis and covalent modification of the obtained cysteine mutants with maleimides, followed by computational elucidation of the possible binding modes. In infected cells, antiviral activity against Dengue virus serotype 2 using prodrugs of the inhibitors was observed. In summary, a novel inhibitor scaffold targeting an allosteric site shared between flaviviral NS2B/NS3 proteases is presented whose efficacy is demonstrated in vitro and in cellulo.

A model system of two related enzymes with conserved binding sites, namely N-myristoyltransferase from two different organisms, was studied to decipher the driving forces that lead to selective inhibition in such cases. Using a combination of computational and experimental tools, two different selectivity-determining features were identified. For some ligands, a change in side-chain flexibility appears to be responsible for selective inhibition. Remarkably, this was observed for residues orienting their side chains away from the ligands. For other ligands, selectivity is caused by interfering with a water molecule that binds more strongly to the off-target than to the target. On the basis of this finding, a virtual screen for selective compounds was conducted, resulting in three hit compounds with the desired selectivity profile. This study delivers a guideline on how to assess selectivity-determining features in proteins with conserved binding sites and to translate this knowledge into the design of selective inhibitors. acceptedVersion

Objective Case reports and a case series have described relief of neuropathic pain (NP) after treatment with epidermal growth factor receptor inhibitors (EGFR-Is). These observations are supported by preclinical findings. The aim of this trial was to explore a potential clinical signal supporting the therapeutic efficacy of EGFR-Is in NP. Methods In a proof-of-concept trial using a randomized, double-blind, placebo-controlled design, 14 patients with severe, chronic, therapy-resistant NP due to compressed peripheral nerves or complex regional pain syndrome were randomized to receive a single infusion of the EGFR-I cetuximab and placebo in crossover design, followed by a single open-label cetuximab infusion. Results The mean reduction in daily average pain scores three to seven days after single-blinded cetuximab infusion was 1.73 points (90% confidence interval [CI] = 0.80 to 2.66), conferring a 1.22-point greater reduction than placebo (90% CI = –0.10 to 2.54). Exploratory analyses suggested that pain reduction might be greater in the 14 days after treatment with blinded cetuximab than after placebo. The proportion of patients who reported ≥50% reduction in average pain three to seven days after cetuximab was 36% (14% after placebo), and comparison of overall pain reduction suggests a trend in favor of cetuximab. Skin rash (grade 1–2) was the most frequent side effect (12/14, 86%). Conclusions This small proof-of-concept evaluation of an EGFR-I against NP did not provide statistical evidence of efficacy. However, substantial reductions in pain were reported, and confidence intervals do not rule out a clinically meaningful treatment effect. Evaluation of EGFR-I against NP therefore warrants further investigation.

Neuropathic pain (NP) represents an unmet medical need, where analgesic responses to different epidermal growth factor receptor inhibitors (EGFR-Is) have been described. The human EGFR family of receptors consists of four members (human epidermal growth factor receptor, HER 1–4), signalling via different homodimer and heterodimer combinations. A 52-year-old man was treated with the EGFR-I cetuximab in a trial of severe NP. Pain scores decreased dramatically after blinded cetuximab, but not after placebo. On pain recurrence after the trial, he was prescribed the oral EGFR-Is erlotinib, gefitinib, and lapatinib without relief. However, treatment with the pan-HER-inhibitor afatinib was effective. After 4 years on afatinib, pain control remains excellent with manageable side effects. This is the first reported observation of differential effects of EGFR-Is on NP in the same patient and the first report describing NP relief with afatinib. Further understanding of the underlying pathophysiology could lead to development of EGFR-Is specifically targeting NP.

Viral and parasitic pathogens rely critically on cysteine proteases for host invasion, replication, and infectivity. Their inhibition by synthetic inhibitors, such as vinyl sulfone compounds, has emerged as a promising treatment strategy. However, the individual reaction steps of protease inhibition are not fully understood. Using the trypanosomal cysteine protease rhodesain as a medically relevant target, we design photoinduced electron transfer (PET) fluorescence probes to detect kinetics of binding of reversible and irreversible vinyl sulfones directly in solution. Intriguingly, the irreversible inhibitor, apart from its unlimited residence time in the enzyme, reacts 5 times faster than the reversible one. Results show that the reactivity of the warhead, and not binding of the peptidic recognition unit, limits the rate constant of protease inhibition. The use of a reversible inhibitor decreases the risk of off-target side effects not only by allowing its release from an off-target but also by reducing the rate constant of binding.

Introduction: EVs released from cells are nanosized vesicles (containing proteins and nucleic acids) that serve as a communication system with other cells or expel cellular waste. Variations in the mtDNA sequence can act as functional adaptors allowing tumor and immune cells to adjust the metabolic needs imposed by various tissue environments during cancer progression. Recent reports have demonstrated that the entire mitochondrial genome can be encapsulated and secreted in EVs. However, the biological attributes of secreted cell-free mtDNA still remain insufficiently understood, mostly because of the difficulty in isolating and characterizing the entire mitochondrial genomes. Here, we present the results from sequencing of mtDNA from various blood compartments, including EVs, and tumor tissue from CRC patients. Methods: Plasma EVs (median mode size 136.4 nm) were isolated by size exclusion chromatography. We compared the mtDNA in EVs with that in whole blood (WB), peripheral blood mononuclear cells (PBMCs), and formalin-fixed paraffin-embedded (FFPE) tumor samples from eight rectal cancer patients. Total DNA was isolated from the four tissue types before the mtDNA was enriched by applying two different PCR approaches with either multiple (for FFPE tumor) or only two (for EVs, WB, and PBMCs) primer sets prior to NGS analysis. WB- and fresh-frozen (FF) tumor mtDNA from eight colon cancer patients was sequenced as controls for the two PCR primer approaches. mtDNA sequence mapping and variant analyses were done using the revised Cambridge Reference Sequence, and HaploGrep2- and Variant Effect Predictor softwares. Results: EV mtDNA presented twice as many variants with significantly more heteroplasmy (mutant mtDNA copies mixed with wild-type copies) than mtDNA from WB and PBMCs. The proportion of EV mtDNA variants that were non-synonymous (i.e. estimated to affect the mitochondrial function) was significantly higher than in WB. FFPE tumors, requiring the multi-primer approach, showed a manyfold increase in detected mtDNA variants, which was not observed for FF tumor mtDNA amplified like WB mtDNA. However, several mtDNA variants detected in FFPE- and FF tumors were not retrieved in WB. Conclusion: We successfully isolated and sequenced the mtDNA cargo of plasma EVs for comparison with mtDNA in WB, PBMCs, and tumor tissue from CRC patients. The EV mtDNA exhibited higher diversity than in the other blood compartments, with a higher degree of heteroplasmy and more variants with impact on the mitochondrial function. The majority of additional mtDNA variants detected in FFPE tumors were possibly caused by technical biases (the tissue processing or mtDNA amplification procedure). Plasma EVs may be involved in the metabolic homeostasis of tumor and immune cells in CRC patients. Citation Format: Tonje Bjørnetrø, Paula A. Bousquet, Kathrine R. Redalen, Anne-Marie S. Trøseid, Torben Lüders, Christin Johansen, Anniken J. Fuglestad, Christian Kersten, Sebastian Meltzer, Anne H. Ree. Next-generation sequencing (NGS) reveals higher mitochondrial DNA (mtDNA) diversity in plasma extracellular vesicles (EVs) than in other blood components and tumor tissue from colorectal cancer (CRC) patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1964.

Purpose: Immune checkpoint inhibition (ICI) may result in tumor response patterns that differ from efficacy measures of directly cytotoxic chemotherapies. Hence, the selection of patients for experimental ICI schedules, for instance in MSS-mCRC, calls for applicable and reliable signals of activity or early failure that enable treatment adaptation and maintain patient safety. Experimental procedures: In the ongoing METIMMOX phase 2 study, we hypothesize that patients with previously untreated unresectable MSS-mCRC can obtain durable disease control to ICI when given short-course oxaliplatin-based chemotherapy (2 cycles of FLOX Q2W) before 2 cycles of nivolumab (240 mg Q2W) in a repeat sequential schedule to a total of 8 cycles. Patients have been randomly assigned to either this experimental study arm or a control arm of 8 FLOX cycles Q2W (standard-of-care; SoC), in both cases before treatment break until disease progression and reintroduction of a new treatment sequence. Radiologic response assessment is performed every 8 weeks with progression-free survival (PFS) as the primary end point. Results: At analysis 10 November 2021, median PFS was 9.3 months (95% CI, 8.3-10.3) for SoC (n = 34) and 11.4 months (95% CI, 7.4-15.5) for the experimental therapy (n = 39) (p = 0.335; log-rank test). In the latter group, 37 patients had available response evaluation at minimum 8 weeks of study treatment, as 2 patients (compared to 4 in the control group) had discontinued treatment due to intolerable toxicity before the first post-baseline assessment. The control arm patients had deeper responses with mean 23% (SD, 19%) target lesion reduction compared to mean 8%(SD, 33%) reduction for the experimental schedule (p = 0.028; Student’s t-test). We categorized the experimental arm patients into those with ≥10% (n = 20) or Conclusions: While the SoC first-line chemotherapy resulted in deeper early responses, target lesion reduction of ≥10% at 8 weeks identified MSS-mCRC patients who held ICI responsiveness evoked by short-course oxaliplatin-based chemotherapy, with significantly improved PFS compared to the SoC. An early radiologic signal of clinical activity may guide the selection of patients to the safe continuation of investigational ICI schedules; however, we do not know if adopting it may compromise prognosis for patients with early ICI failure who can proceed with SoC. Citation Format: Sebastian Meltzer, Anne Negård, Hanne Mari Hamre, Christian Kersten, Eva Hofsli, Marianne Grønlie Guren, Halfdan Sørbye, Kjersti Flatmark, Anne Hansen Ree. Early radiologic signal of nivolumab responsiveness after short-course oxaliplatin-based chemotherapy in microsatellite-stable (MSS) metastatic colorectal cancer (mCRC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1279.

Inhibition of coronavirus (CoV)‐encoded papain‐like cysteine proteases (PLpro) represents an attractive strategy to treat infections by these important human pathogens. Herein we report on structure‐activity relationships (SAR) of the noncovalent active‐site directed inhibitor (R)‐5‐amino‐2‐methyl‐N‐(1‐(naphthalen‐1‐yl)ethyl) benzamide (2 b), which is known to bind into the S3 and S4 pockets of the SARS‐CoV PLpro. Moreover, we report the discovery of isoindolines as a new class of potent PLpro inhibitors. The studies also provide a deeper understanding of the binding modes of this inhibitor class. Importantly, the inhibitors were also confirmed to inhibit SARS‐CoV‐2 replication in cell culture suggesting that, due to the high structural similarities of the target proteases, inhibitors identified against SARS‐CoV PLpro are valuable starting points for the development of new pan‐coronaviral inhibitors., Valuable starting points: Within this study, the effectivity of naphthalene‐based inhibitors, formerly developed against the papain‐like protease (PLpro) of the severe acute respiratory syndrome (SARS)‐causing coronavirus (CoV), against the homologous PLpro of SARS‐CoV‐2 is shown. Furthermore, isoindoline is presented as an innovative scaffold for this inhibitor type. In particular, high antiviral activity combined with low cytotoxicity are highlights of these inhibitors.