Lysis-deficient phages as novel therapeutic agents for controlling bacterial infection

<p>Abstract</p> <p>Background</p> <p>Interest in phage therapy has grown over the past decade due to the rapid emergence of antibiotic resistance in bacterial pathogens. However, the use of bacteriophages for therapeutic purposes has raised concerns over the potential for immune response, rapid toxin release by the lytic action of phages, and difficulty in dose determination in clinical situations. A phage that kills the target cell but is incapable of host cell lysis would alleviate these concerns without compromising efficacy.</p> <p>Results</p> <p>We developed a recombinant lysis-deficient <it>Staphylococcus aureus </it>phage P954, in which the endolysin gene was rendered nonfunctional by insertional inactivation. P954, a temperate phage, was lysogenized in <it>S. aureus </it>strain RN4220. The native endolysin gene on the prophage was replaced with an endolysin gene disrupted by the chloramphenicol acetyl transferase (<it>cat</it>) gene through homologous recombination using a plasmid construct. Lysogens carrying the recombinant phage were detected by growth in presence of chloramphenicol. Induction of the recombinant prophage did not result in host cell lysis, and the phage progeny were released by cell lysis with glass beads. The recombinant phage retained the endolysin-deficient genotype and formed plaques only when endolysin was supplemented. The host range of the recombinant phage was the same as that of the parent phage. To test the <it>in vivo </it>efficacy of the recombinant endolysin-deficient phage, immunocompromised mice were challenged with pathogenic <it>S. aureus </it>at a dose that results in 80% mortality (LD₈₀). Treatment with the endolysin-deficient phage rescued mice from the fatal <it>S. aureus </it>infection.</p> <p>Conclusions</p> <p>A recombinant endolysin-deficient staphylococcal phage has been developed that is lethal to methicillin-resistant <it>S. aureus </it>without causing bacterial cell lysis. The phage was able to multiply in lytic mode utilizing a heterologous endolysin expressed from a plasmid in the propagation host. The recombinant phage effectively rescued mice from fatal <it>S. aureus </it>infection. To our knowledge this is the first report of a lysis-deficient staphylococcal phage.</p

Lanthanum halide nanoparticle scintillators for nuclear radiation detection

Nanoparticles with sizesscintillators, in order to determine the viability of using scintillators employing nanostructured lanthanum trifluoride. Preliminary results of this investigation are consistent with the idea that these materials have an intrinsic response to nuclear radiation that may be correlated to the energy of the incident radiation

Antistaphylococcal activity of bacteriophage derived chimeric protein P128

<p>Abstract</p> <p>Background</p> <p>Bacterial drug resistance is one of the most significant challenges to human health today. In particular, effective antibacterial agents against methicillin-resistant <it>Staphylococcus aureus </it>(MRSA) are urgently needed. A causal relationship between nasal commensal <it>S. aureus </it>and infection has been reported. Accordingly, elimination of nasal <it>S. aureus </it>reduces the risk of infection. Enzymes that degrade bacterial cell walls show promise as antibacterial agents. Bacteriophage-encoded bacterial cell wall-degrading enzymes exhibit intrinsic bactericidal activity. P128 is a chimeric protein that combines the lethal activity of the phage tail-associated muralytic enzyme of Phage K and the staphylococcal cell wall targeting-domain (SH3b) of lysostaphin.</p> <p>Here we report results of in vitro studies evaluating the susceptibility of staphylococcal strains to this novel protein.</p> <p>Results</p> <p>Using the broth microdilution method adapted for lysostaphin, we found that P128 is effective against <it>S. aureus </it>clinical strains including MRSA, methicillin-sensitive <it>S. aureus </it>(MSSA), and a mupirocin-resistant <it>S. aureus</it>. Minimum bactericidal concentrations and minimum inhibitory concentrations of P128 (1-64 μg/mL) were similar across the 32 <it>S. aureus </it>strains tested, demonstrating its bactericidal nature.</p> <p>In time-kill assays, P128 reduced colony-forming units by 99.99% within 1 h and inhibited growth up to 24 h.</p> <p>In an assay simulating topical application of P128 to skin or other biological surfaces, P128 hydrogel was efficacious when layered on cells seeded on solid media. P128 hydrogel was lethal to Staphylococci recovered from nares of healthy people and treated without any processing or culturing steps, indicating its in situ efficacy. This methodology used for in vitro assessment of P128 as an agent for eradicating nasal carriage is unique.</p> <p>Conclusions</p> <p>The novel chimeric protein P128 is a staphylococcal cell wall-degrading enzyme under development for clearance of <it>S. aureus </it>nasal colonization and MRSA infection. The protein is active against globally prevalent antibiotic-resistant clinical isolates and other clinically significant staphylococcal species including <it>S. epidermidis</it>. The P128 hydrogel formulation was bactericidal against Staphylococci including <it>S. aureus </it>recovered from the nares of 31 healthy people, demonstrating its in situ efficacy.</p

A novel bacteriophage Tail-Associated Muralytic Enzyme (TAME) from Phage K and its development into a potent antistaphylococcal protein

<p>Abstract</p> <p>Background</p> <p><it>Staphylococcus aureus </it>is a major cause of nosocomial and community-acquired infections. However, the rapid emergence of antibiotic resistance limits the choice of therapeutic options for treating infections caused by this organism. Muralytic enzymes from bacteriophages have recently gained attention for their potential as antibacterial agents against antibiotic-resistant gram-positive organisms. Phage K is a polyvalent virulent phage of the <it>Myoviridae </it>family that is active against many <it>Staphylococcus </it>species.</p> <p>Results</p> <p>We identified a phage K gene, designated <it>orf</it>56, as encoding the phage tail-associated muralytic enzyme (TAME). The gene product (ORF56) contains a C-terminal domain corresponding to cysteine, histidine-dependent amidohydrolase/peptidase (CHAP), which demonstrated muralytic activity on a staphylococcal cell wall substrate and was lethal to <it>S. aureus </it>cells. We constructed N-terminal truncated forms of ORF56 and arrived at a 16-kDa protein (Lys16) that retained antistaphylococcal activity. We then generated a chimeric gene construct encoding Lys16 and a staphylococcal cell wall-binding SH3b domain. This chimeric protein (P128) showed potent antistaphylococcal activity on global clinical isolates of <it>S. aureus </it>including methicillin-resistant strains. In addition, P128 was effective in decolonizing rat nares of <it>S. aureus </it>USA300 in an experimental model.</p> <p>Conclusions</p> <p>We identified a phage K gene that encodes a protein associated with the phage tail structure. The muralytic activity of the phage K TAME was localized to the C-terminal CHAP domain. This potent antistaphylococcal TAME was combined with an efficient <it>Staphylococcus</it>-specific cell-wall targeting domain SH3b, resulting in the chimeric protein P128. This protein shows bactericidal activity against globally prevalent antibiotic resistant clinical isolates of <it>S. aureus </it>and against the genus <it>Staphylococcus </it>in general. <it>In vivo</it>, P128 was efficacious against methicillin-resistant <it>S. aureus </it>in a rat nasal colonization model.</p

Phase I study of nab-paclitaxel, gemcitabine, and bevacizumab in patients with advanced cancers.

BackgroundWe performed a phase I modified 3 + 3 dose escalation study to evaluate the safety and activity of bevacizumab plus gemcitabine and nab-paclitaxel in patients with advanced solid tumours.MethodsPatients were given fixed dose gemcitabine plus increasing doses of nab-paclitaxel and bevacizumab. Toxicity, response, and association with VEGF polymorphism was analysed.ResultsThe study enrolled 110 patients who had undergone a median of 3 prior lines of therapy. The median age was 60 years (range, 17-85 years), and 55 patients (50%) had gemcitabine-refractory disease. We observed 3 dose-limiting toxicities during dose escalation and 3 DLTs in expansion cohorts. Dose escalation to 150 mg/m2 nab-paclitaxel and 15 mg/kg bevacizumab with 1000 mg/m2 of gemcitabine was well tolerated with no MTD. One patient with gemcitabine-refractory peritoneal papillary carcinoma had a complete response, 13 patients (13%) had partial responses, and 54 patients (52%) had stable disease ≥12 weeks. Exploratory VEGF single nucleotide polymorphism (SNP) analysis was performed on 13 patients.ConclusionsThe combination of gemcitabine, nab-paclitaxel, and bevacizumab is safe, well-tolerated, and has activity in advanced malignancies, including gemcitabine-refractory tumours. Based on this study, the recommended phase 2 dose is gemcitabine 1000 mg/m2, nab-paclitaxel 125 mg/m2, and bevacizumab 15 mg/kg. VEGF polymorphism data should be evaluated in future bevacizumab-based trials

A Phase I Trial of Bevacizumab and Temsirolimus in Combination With Valproic Acid in Advanced Solid Tumors

BACKGROUND: Preclinical models suggest synergy between anti-angiogenesis therapy, mammalian target of rapamycin (mTOR), and histone deacetylase inhibitors to promote anticancer activity. METHODS: This phase I study enrolled 47 patients between April 2012 and 2018 and determined safety, maximum tolerated dose (MTD), and dose-limiting toxicities (DLTs) when combining bevacizumab, temsirolimus, and valproic acid in patients with advanced cancer. RESULTS: Median age of enrolled patients was 56 years. Patients were heavily pretreated with a median of 4 lines of prior therapy. Forty-five patients (95.7%) experienced one or more treatment-related adverse events (TRAEs). Grade 3 TRAEs were lymphopenia (14.9%), thrombocytopenia (8.5%), and mucositis (6.4%). Grade 4 TRAEs included lymphopenia (2.1%) and CNS cerebrovascular ischemia (2.1%). Six patients developed DLTs across 10 dose levels with grade 3 infection, rash, mucositis, bowel perforation, elevated lipase, and grade 4 cerebrovascular ischemia. The MTD was dose level 9 (bevacizumab 5 mg/kg days 1 and 15 intravenously (IV) plus temsirolimus 25 mg days 1, 8, 15, and 22 IV and valproic acid 5 mg/kg on days 1-7 and 15-21 per orally (PO)). Objective response rate (ORR) was 7.9% with confirmed partial response (PRs) in 3 patients (one each in parotid gland, ovarian, and vaginal cancers). Stable disease (SD) ≥+6 months was seen in 5 patients (13.1%). Clinical benefit state (CBR: PR + SD ≥+6 months) was 21%. CONCLUSION: Combination therapy with bevacizumab, temsirolimus, and valproic acid was feasible, but there were numerous toxicities, which will require careful management for future clinical development (ClinicalTrials.gov Identifier: NCT01552434)

Phase II Study of Talazoparib in Advanced Cancers With BRCA1/2, DNA Repair, and PTEN Alterations

Cancer cells with BRCA1/2 deficiencies are sensitive to poly (ADP-ribose) polymerase (PARP) inhibitors. We evaluated the efficacy of talazoparib in DNA-Damage Repair (DDR)-altered patients. In this phase II trial, patients were enrolled onto one of four cohorts based on molecular alterations: (1) somatic BRCA1/2, (2) other homologous recombination repair pathway, (3) PTEN and (4) germline BRCA1/2. The primary endpoint was a clinical benefit rate (CBR): complete response, partial response or stable disease ≥24 weeks. 79 patients with a median of 4 lines of therapy were enrolled. CBR for cohorts 1-4 were: 32.5%, 19.7%, 9.4% and 30.6%, respectively. PTEN mutations correlated with reduced survival and a trend towards shorter time to progression.Talazoparib demonstrated clinical benefit in selected DDR-altered patients. PTEN mutations/loss patients derived limited clinical benefit. Further study is needed to determine whether PTEN is prognostic or predictive of response to PARP inhibitors

Predictors of Oncologic Outcome in Patients Receiving Phase I Investigational Therapy for Recurrent or Metastatic Cervical Cancer

INTRODUCTION: We aimed to identify clinical, pathologic, and treatment factors that are predictive of response and survival in patients with cervical cancer referred to phase I clinical trials. METHODS: Patients with cervical cancer who received at least one dose of a phase I investigational agent at our institution between 2014 and 2022 were included. The log-rank test was used to analyze differences in progression-free survival (PFS) and overall survival (OS), and multivariable regression analysis was performed. RESULTS: We included 65 patients with a median age of 41 years (range, 20-74), 3 prior therapies (range, 1-7), and 67.7% squamous carcinoma. The rate of distant metastasis at trial entry was 84.6%. The most common molecular alterations included PIK3CA (46.5%), PD-L1+ (46.2%), EPH (30.0%), and CREBBP (23.1%); 23.1% had received a prior checkpoint inhibitor. Phase I trials were for immunotherapy (58.5%) or targeted therapy (41.5%). The rate of biomarker matching was 21.5%. For all patients, median PFS was 3.6 months (95% CI, 2.0-5.2) and OS was 9.3 months (95% CI, 7.0-10.6). Factors at study entry associated with worse survival were presence of bone metastasis (PFS 1.6 vs 4.4 months: hazard ratio [HR], 2.8; CONCLUSION: Bone metastasis and absolute lymphocyte count below normal range at phase I study entry portend poor survival in patients with recurrent or metastatic cervical cancer

Challenges and Opportunities Associated With the MD Anderson IMPACT2 Randomized Study in Precision Oncology

We investigated the challenges of conducting IMPACT2, an ongoing randomized study that evaluates molecular testing and targeted therapy (ClinicalTrials.gov: NCT02152254). Patients with metastatic cancer underwent tumor profiling and were randomized between the two arms when eligibility criteria were met (Part A). In Part B, patients who declined randomization could choose the study arm. In Part A, 69 (21.8%) of 317 patients were randomized; 78.2% were not randomized because of non-targetable alterations (39.8%), unavailability of clinical trial (21.8%), other reasons (12.6%), or availability of US Food and Drug Administration (FDA)-approved drugs for the indication (4.1%). In Part B, 32 (20.4%) of 157 patients were offered randomization; 16 accepted and 16 selected their treatment arm; 79.0% were not randomized (patient\u27s/physician\u27s choice, 29.3%; treatment selection prior to genomic reports, 16.6%; worsening performance status/death, 12.7%; unavailability of clinical trials, 6.4%; other, 6.4%; non-targetable alterations, 5.7%; or availability of FDA-approved drugs for the indication, 1.9%). In conclusion, although randomized controlled trials have been considered the gold standard for drug development, the execution of randomized trials in precision oncology in the advanced metastatic setting is complicated. We encountered various challenges conducting the IMPACT2 study, a large precision oncology trial in patients with diverse solid tumor types. The adaptive design of IMPACT2 enables patient randomization despite the continual FDA approval of targeted therapies, the evolving tumor biomarker landscape, and the plethora of investigational drugs. Outcomes for randomized patients are awaited