EEF1A1

Scientists have found that human ribosomes decode mRNA slower than bacteria, with implications for drug development. Scientists at St. Jude Children's Research Hospital revealed that human ribosomes decode messenger RNA (mRNA) 10 times slower than bacterial ribosomes, but do so more accurately. The study, published today in Nature, used a combination of field-leading structural biology approaches to better understand how ribosomes work. The scientists pinpointed where the process slows down in humans, which will be useful information for developing new therapeutics for cancer and infections. Ribosomes are molecular machines within cells, responsible for synthesizing proteins by decoding mRNA. By conducting mechanistic studies on bacterial and human ribosomes, researchers can understand their similarities and differences to develop drugs and understand disease. Many antibiotics, the drugs we use to treat bacterial infections, work by targeting bacterial ribosomes. In humans, changes in how accurately ribosomes decode mRNA have been linked to aging and disease, representing a potential point of therapeutic intervention. This gives the work implications for the treatment of infections and cancer. "Bacteria have been very well studied for many decades, but the kind of studies that we do, careful mechanistic studies, have been missing on human ribosomes," said corresponding author Scott Blanchard, Ph.D., St. Jude Department of Structural Biology. "We're very interested in human ribosomes because those are what need to be targeted to find new treatments for cancer and viral infections such as COVID." Resolution revolution Ribosomes decode mRNA using a molecule called aminoacyl-transfer RNA (tRNA) as substrate. The decoding process involves several different steps. The researchers deployed methods such as single-molecule fluorescence resonance energy transfer (smFRET) and cryo-electron microscopy (cryo-EM) to examine the human ribosome decoding mechanisms. The single-molecule imaging gives the researchers information on how quickly things occur. So, in this case, how quickly human ribosomes go through the different steps during the decoding process. Cryo-EM gives the researchers structural information. So, how the human ribosome looks or what conformations (shapes) it is in at each step. By combining these two methods, the scientists get information on how quickly these processes occur in humans compared to bacteria as well as about the underlying structural causes for any differences they observe. "We wanted to know how quickly a human ribosome can read the genetic code, how quickly it finds the tRNA that's complementary to the mRNA," said co-first author Mikael Holm, Ph.D., St. Jude Department of Structural Biology. "We found that the process is about 10 times slower for human ribosomes than it is in bacteria. But this slow down adds accuracy, because human ribosomes are known to be more accurate at translating the code than bacterial ribosomes." Specifically, the researchers found that while humans and bacteria both decode mRNA, the reaction pathway of aminoacyl-tRNA movement during the decoding process is different on human ribosomes and is significantly slower. These differences arise from structural elements in the human ribosome and in the human elongation factor, eEF1A, that together are responsible for faithfully incorporating the right tRNA for each mRNA codon (piece of the sequence). The distinct nature and timing of conformational changes within the ribosome and eEF1A may explain how human ribosomes achieve greater decoding accuracy. "With our cryo-EM structural studies, we were able to resolve human ribosome structures to atomic resolution, which revealed unprecedented features such as rRNA and protein modifications, ions and solvent molecules present in the human ribosome," said co-first author Kundhavai Natchiar, Ph.D., St. Jude Department of Structural Biology. "These features finely characterize the molecular basis of interactions of the drug molecules with the human ribosome, which is indispensable for human ribosome-based drug design and discovery." Caught in the act The researchers also pinpointed exactly which step of the decoding process slowed down in human ribosomes. There are two steps in the process of the ribosome selecting the right tRNA: initial selection and proofreading selection. The second step, proofreading selection, is where the ribosome checks for a second time that it chose the right molecule. That is the step that is 10 times slower in humans than in bacteria. Think of a gymnast, contorting themselves into different shapes on the mat as they work through their routine. This is similar to how ribosomes transition into various conformations to achieve different results. The research showed that a lot of conformational gymnastics that human ribosomes undergo are not present in bacterial ribosomes and are thus likely tied to the slowdown of the proofreading selection process. The researchers also found that several drugs target the proofreading selection process, not initial selection. So, instead of hitting the step that is similar between humans and bacteria, these drugs focus on the most different, slowest step. "In structural biology, a single snapshot of a macromolecular machine is not always sufficient to explain how it functions," said co-first author Emily Rundlet, Ph.D., St. Jude Department of Structural Biology. "Often, the snapshot that's needed to answer your biological question is not the most stable form of the molecule, but instead it is short-lived and difficult to capture. Using smFRET and cryo-EM together brings the dimension of time to structural biology, which allows us to visualize important transient intermediate steps of human decoding and understand the different mechanisms on a new level."

Vaccines against COVID-19 were developed in record time, but the successful advancement of therapeutics, particularly those that could disrupt the CARS-CoV-2 virus cycle, have been slower to move through the clinic. Researchers at multiple companies and institutes are doggedly pursuing that goal so the virus can become little more than a hindrance in the future. A recent PBS report highlighted some of these efforts, focusing on clinical programs that have the potential to halt viral reproduction and keep those infected out of the hospitals. Experimental medications such as molnupiravir, in development by Merck and Florida-based Ridgeback Biotherapeutics, have the potential to fill the treatment gaps that vaccines cannot. Merck and Ridgeback are jointly developing molnupiravir, an orally available antiviral candidate for the treatment of COVID-19. Earlier this year, the two companies noted a slight setback in the development of that program. In April, Merck announced it was moving molnupiravir into the Phase III portion of the Phase II/III MOVE-OUT study in outpatient COVID-19 patients based on a planned interim analysis from the Phase II part of the study. However, at the time, the companies said the Phase III portion of another study, the Phase II/III MOVE-IN study in hospitalized patients, will not proceed due to data that suggests molnupiravir is unlikely to demonstrate a clinical benefit in that patient population. Daria Hazuda, vice president of infectious disease and vaccine discovery research at Merck, said they are hopeful the Phase III portion of the study, expected to be complete later this year, will demonstrate that molnupiravir is an effective treatment for mild to moderate cases of COVID-19. Beyond Merck, PBS noted research conducted by Adolfo Garcia-Sastre, the director of the Global Health and Emerging Pathogens Institute at Icahn School of Medicine at Mount Sinai and the University of California, San Francisco’s Quantitative Biosciences Institute. After extensive research on multiple antiviral options, the collaborators put their focus on plitidepsin, an injectable multiple myeloma drug medicine developed by Spain’s PharmaMar. Plitidepsin acts by blocking the protein eEF1A, present in human cells, which SARS-CoV-2 uses to reproduce and infect other cells. Through this inhibition, the expectation is that reproduction of the virus inside the cell is prevented, making this propagation to the rest of the cells unviable. Phase III research of plitidepsin was greenlit by Spanish health authorities last month. The scientific team hopes to see if the oncology drug effectively reduces days in the hospital for COVID-19 patients. In its report, the results of compare plitidepsin’s effectiveness in the Phase III study would be compared to Gilead Sciences’ remdesivir, which is currently the standard of care for COVID-19. Remdesivir, the only antiviral approved to treat COVID-19, can shorten the hospital stay of COVID-19 patients, it has fallen short in treating patients. Garcia-Sastre told PBS he hopes plitidepsin will demonstrate live-saving potential. Another potential antiviral highlighted by the news outlet is ivermectin, a decades-old drug approved to treat head lice infections as well as the treatment of some parasitic worms. Research has shown in a laboratory setting that the use of ivermectin inhibited the SARS-CoV-2 virus within 24 to 48 hours of treatment. The preclinical data showed that ivermectin prevented the virus’ RNA from replicating. While COVID-19 is not a parasitic disease, the laboratory tests showed that the drug targets the disease like one.

It was a busy week for clinical trial announcements. Here’s a look. COVID-19-Related All India Institute of Medical Sciences (AIIMS) indicated that Bharat Biotech’s COVID-19 vaccine, Covaxin, may offer immunity for nine to 12 months, based on mathematical models. The vaccine was already approved before the release of Phase III data and was used to inoculate healthcare workers during the Phase I trial. Clene Nanomedicine initiated a Phase II trial of CNM-ZnAg liquid solution in acutely symptomatic, non-hospitalized COVID-19 patients. The primary endpoint will evaluate the rate of decreased hospitalizations at day 28. CNM-ZnAg is a proprietary zinc-silver ionic solution that has both antiviral and antibacterial properties as well as immune-boosting properties. Oxford University announced it began testing its COVID-19 vaccine in children as young as six years of age. The study will include 300 children ages 6 to 17, with 240 receiving the vaccine co-developed with AstraZeneca. The remaining volunteers will receive a control meningitis vaccine that has been proven safe in children but is believed to mimic side effects of the COVID-19 vaccine. Mesoblast Limited published results on the first two children treated with its mesenchymal stromal cell (MSC) product candidate, remestemcel-L for multisystem inflammatory syndrome (MIS-C) associated with COVID-19. MIS-C is a potentially life-threatening inflammatory conditions involving multiple critical organs and their vasculature. It is linked to previous, instead of active COVID-19 infection. PTC Therapeutics initiated the second stage of the Phase II/III FITE19 clinical trial of PTC299 in COVID-19 patients. PTC299 is an oral drug with dual mechanisms of action that potentially inhibits viral replication and attenuates the uncontrolled inflammatory response post-infection. The drug targets dihydroorotate dehydrogenase (DHODH). Altimmune received the go-ahead from the FDA for its Phase I trial of AdCOVID, its single-dose, intranasal COVID-19 vaccine. It will test the safety and immunogenicity of the vaccine in up to 180 healthy adult volunteers ages 18 to 55. Pharma Mar SA received approval in the UK to initiate its Phase III NEPTUNO trial of Aplidin (plitidepsin) for hospitalized patients with moderate COVID-19. The trial is expected to run in 12 countries but was first authorized in the UK. It hopes to enroll more than 600 patients. Aplidin blocks the eEF1A protein, which SARS-CoV-2 uses to replicate and infect other cells. Biophytis SA began patient recruitment in France and Belgium for Part 2 of its COVA Study assessing Sarconeos for acute respiratory failure associated with COVID-19. Sarconeos is an oral, small molecule being developed for sarcopenia and severe respiratory aspects of COVID-19, as well as in a pediatric formulation for Duchenne muscular dystrophy (DMD). EmitBio announced statistically significant efficacy results from its Phase I/II trial of its medical device that directs precise wavelengths of safe, visible light targeted to the back of the throat and surrounding tissues. The device was designed for self-treatment of COVID-19 in an at-home setting. Diffusion Pharmaceuticals completed and announced topline data from its Phase Ib trial of its diffusion-enhancing therapeutic, trans sodium crocetinate, in hospitalized COVID-19 patients with confirmed hypoxemia. The primary endpoint was safety and tolerability, with secondary endpoints being pharmacokinetic measurement of trans sodium crocetinate levels after dosing, relative improvements in blood oxygen levels, and other clinical measures associated with COVID-19. Pfizer and BioNTech dosed the first patients in a clinical trial of 4,000 women in the late stages of pregnancy yesterday. The two companies will run the Phase II trial for 350 volunteers between 27 and 34 weeks’ gestation to confirm safety before moving into the Phase III portion for women between 24 and 34 weeks of pregnancy. AstraZeneca and Johnson & Johnson also plan to run trials in the coming months on pregnant women. CMTx Biotech received a $315,000 Clinical Trial Planning Grant from the NIH’s National Center for Advancing Translational Sciences to finalize a Phase II trial of incyclinide. The drug is its candidate for treatment of hospitalized COVID-19 patients. The drug is a non-antimicrobial tetracycline formulation, which is the specialty of CMTx. “Incyclinide has already been shown to be highly effective in a number of animal models of acute respiratory distress syndrome across several species,” noted Lorne Golub, co-founder of CMTx and SUNY Distinguished Professor of Oral Biology and Pathology. Non-COVID-19-Related Merck presented new data from the Phase III CLEAR trial (KEYNOTE-581/Study 307) of its checkpoint inhibitor Keytruda (pembrolizumab) and Eisai’s tyrosine kinase inhibitor Lenvima (lenvatinib) in renal cell carcinoma. The combination of Keytruda and Lenvima was compared to Lenvima plus everolimus versus Pfizer’s Sutent (sunitinib) for first-line treatment of patients with advanced renal cell carcinoma (RCC). The combination of Keytruda and Lenvima demonstrated statistically significant and clinically meaningful improvements in progression-free survival (PFS), overall survival (OS) and objective response rate (ORR) compared to sunitinib. The Lenvima-everolimus combination also demonstrated statistically significant improvements in PFS and ORR compared to sunitinib. In exploratory analysis, the data for PFS and OS were consistent across prespecified Memorial Sloan Kettering Cancer Center (MSKCC) risk groups, in other words, favorable, intermediate, and poor. bluebird bio announced that it has placed its Phase I/II and Phase III trial of LentiGlobin gene therapy for sickle cell disease (SCD) on temporary suspension. The cause is a Suspected Unexpected Serious Adverse Reaction (SUSAR) of acute myeloid leukemia (AML). HGB-206 is the company’s ongoing Phase I/II trial of LentiGlobin for SCD. It includes three cohorts, A, B and C. In Group C, a refined manufacturing process designed to increase vector copy number was used. Group C also received LentiGlobin for SCD manufactured from hematopoietic (blood) stem cells (HSCs) collected from peripheral blood after mobilization with plerixafor, instead of by way of bone marrow harvest, which was the method used in Groups A and B. HGB-210 is their ongoing Phase III single-arm open-label trial. It is evaluating efficacy and safety of LentiGlobin for SCD in patients between two years and 50 years of age with sickle cell disease. Histogen announced week 26 results from its Phase Ib/IIa trial of HST-001 in male patients with androgenic alopecia—hair loss. At the timepoint, patients receiving the drug demonstrated statistically significant change from baseline in total hairs in the target area. HST-001, or Hair Stimulating Complex (HSC), is designed to be a physician-administered treatment for hair loss. Recce Pharmaceuticals formalized a deal with Fiona Stanley Hospital in Australia for a Phase I/II trial of RECCE 327, its new spray-on, broad-spectrum antibiotic for topical burn wound infections. It will enroll up to 30 patients. Eli Lilly announced results from its SURPASS-3 and SURPASS-5 Phase III trials after 52 weeks and 40 weeks, respectively. SURPASS-3 compared tirzepatide to titrated insulin degludec and SURPASS-5 compared tirzepatide to placebo, both as an add-on to titrated insulin glargine. All primary and all key secondary endpoints were met. Tirzepatide is a once-weekly dual glucose-dependent insulinotropic polypeptide (GIP) and GLP-1 receptor agonist being evaluated for type 2 diabetes. The drug significantly reduced A1C and body weight in type 2 diabetes. Selecta Biosciences and AskBio initiated first-in-human dose escalation Phase I trial of SEL-399. SEL-399 is an AAV serotype 8 empty vector capsid containing no DNA combined with ImmTOR. The trial is to determine the optimal dose of ImmTOR to mitigate the formation of antibodies to AAV8 capsids used in gene therapies. Salarius Pharmaceuticals completed the dose-escalation stage and established the recommended Phase II dose for its ongoing Phase I/II trial for seclidemstat in r/r Ewing sarcoma. Seclidemstat is a novel, oral reversible inhibitor of the lysine-specific histone demethylase 1 enzyme (LSD1), which plays a key role in the development and progression of certain cancers. AstraZeneca and Merck announced the OlympiA Phase III trial for Lynparza (Olaparib) will move to early primary analysis and reporting after a recommendation from the Independent Data Monitoring Committee (IDMC). The IDMC decided the trial crossed the superiority boundary for its primary endpoint of invasive disease-free survival (iDFS) and demonstrated a sustainable, clinically relevant treatment effect for Lynparza compared to placebo for patients with germline BRCA-mutated high-risk HER2-negative early breast cancer. Ocuphire Pharma initiated enrollment in its Phase II VEGA-1 trial of a combination kit of Nyxol and low-dose pilocarpine in presbyopia. Nyxol is believed to improve near vision based on its ability to reduce pupil diameter, which results in increased depth of field. Dermavant Sciences announced positive safety and efficacy data from a planned interim analysis of PSOARING 3 of tapinarof in adults with plaque psoriasis. Tapinarof is a novel, once-daily aryl hydrocarbon receptor modulating agent (TAMA). Flexion Therapeutics announced plans to advance FX201 into the high dose cohort of the Phase I trial. FX201 is an intra-articular, IL-1Ra gene therapy product for osteoarthritis. ChemoCentryx published data from its Phase III ADVOCATE trial of avacopan in patients with anti-neutrophil cytoplasmic autoantibody-associated vasculitis (ANCA-associated vasculitis or ANCA vasculitis). Avacopan is an oral selective complement 51 receptor inhibitor. Treatment with avacopan in the absence of daily oral prednisone led to remission at week 26 and superiority in sustaining remission at 52 weeks compared to the prednisone group. vTv Therapeutics initiated its Phase I trial of orally administered phosphodiesterase type 4 inhibitor, HPP737 in healthy adults. The drug is being developed for the treatment of psoriasis. Most Read Today