Biotech-2021, part 2

The most important biomedicine news of the second half of 2021

Ilya Yasny, XX2 century

The subtleties of the human genome, new vaccines, medicines for previously incurable diseases, cunningly twisted DNA and a soluble pacemaker. We present to your attention our traditional semi-annual review of the most important, notable and breakthrough events in the field of biomedical technologies.

Covid

During the pandemic, covid claimed the lives of almost 5.5 million people and is not going to stop yet. In Russia, according to official statistics, more than 300,000 people have died from covid, but demographers say about one million people have excess mortality.

At the end of 2021, Omicron became the leading option, which is more contagious than the previous ones, but, according to available data, does not cause such a severe course of the disease as Delta and other previously common variants. However, greater contagion means that the number of hospitalized people will also grow, which poses a threat of overloading healthcare systems. Therefore, countries began to resort to quarantines and lockdowns again, and most importantly — to continue vaccination. It has been shown that, although Omicron infects vaccinated and ill patients more easily compared to previous variants, the third vaccination (booster) is able to raise protection almost to the initial level (Fig. 1).

Figure 1. Decrease in the effectiveness of the vaccine over time. Squares — Delta, circles — Omicron. BioNTech/Pfizer vaccine BNT162b2, mRNA-1273 — Moderna vaccine. Source.

But the two years of the pandemic will also go down in history as an era of incredible breakthroughs in the development of vaccines and medicines. The fact that in a few months it was possible to develop and produce several very effective and safe vaccines in large quantities (Fig. 2) is evidence of the high level of modern biotechnologies (although, of course, it was not without a share of luck either). It's all the more insulting that many still do not want to be vaccinated with them: but at the beginning of the year it seemed that the pandemic would be defeated by the end of 2021.

Figure 2. Mortality from COVID-19 adjusted for age, per 100,000 population. Blue graph — unvaccinated, blue — vaccinated, less than 21 days from the first dose, red — vaccinated, more than 21 from the first dose, green — two doses. Source.

Therapeutic drugs are more complicated: until the end of 2021, only the results of studies of pre-existing drugs appeared, most of which did not show efficacy as expected (ivermectin, hydroxychloroquine, favipiravir and many others), and only some, such as dexamethasone, anticoagulants and to a lesser extent remdesivir and tocilizumab showed efficacy in hospitalized patients. Monoclonal antibodies were created, which showed some effectiveness, but also only in severe patients.

But in December 2021, the first tablet drug Pakslovid, developed specifically against COVID-19, was registered in the United States for outpatient treatment. In a clinical study, he reduced the chance of going to the hospital or dying by almost 10 times. The company 's molnupiravir was also registered Merck & Co, but its effectiveness is more modest — it reduces hospitalization and mortality by 30%. Molnupiravir has shown signs of teratogenicity in animals, so it is not indicated for pregnant women, and its potential effect on bone and joint growth does not allow it to be prescribed to persons under 18 years of age.

According to some scenarios, in 2022 the pandemic can be defeated by a combination of vaccination, quarantine measures and therapy. In other scenarios, the virus will continue to evolve and give us surprises.

Now to other, non-comical news.

Mirror Life

Scientists from Tsinghua University in Beijing carried out an amazingly painstaking work to create a completely mirror copy of a natural protein, and with its help they created mirror DNA.

As you know, many organic compounds, including most of those that make up our cells, can exist in two types (enantiomers), which differ from each other like mirror reflections. From a physical and chemical point of view, enantiomers do not differ in any way, unless they enter into reactions where other enantiomers participate. It so happened that living systems use only one type of enantiomers from the very beginning of their appearance. Since amino acids, nucleotides and sugars are chiral (have enantiomers), proteins, DNA and polysaccharides that consist of them are also chiral. And since they are formed from building blocks of the same kind, they have only one possible mirror conformation. Scientists have long been interested in how biomolecules will behave if they are mirrored. In particular, it is clear that mirror nucleic acids will be much more stable, because they will not be broken down by natural enzymes-nucleases — the main reason for the rapid degradation of DNA and — especially — RNA.

Previously, attempts were made to chemically synthesize relatively small proteins (up to 164 amino acids) and short sections of DNA (up to 150 nucleotides). Recently, Chinese scientists have begun to advance in the field of synthesis of DNA polymerases - enzymes that lengthen the DNA chain. Recently, they managed to synthesize polymerases up to 352 amino acids in size, but they make a lot of mistakes in DNA.

In the new work, a Pfu polymerase with a length of 775 amino acids was synthesized (Fig. 3) — one of the most accurate polymerases, which is therefore used worldwide in PCR laboratories. This was achieved by splitting its sequence into 15 fragments with a length of about 30-60 amino acids and a variety of substitutions that facilitate the synthesis and assembly of the molecule.

Figure 3. On the left — natural Pfu polymerase, on the right — mirror. Source.

To test the efficiency of the enzyme, scientists synthesized a DNA strand with its help, and at once with a length of 1500 base pairs! DNA was not chosen by chance — it encodes one of the main components of the ribosome — 16S-rRNA, that is, scientists are aiming to create a completely mirror system of protein synthesis, and in the future — the whole cell. In addition, they demonstrated the possibility of using mirror DNA to store information and tag samples.

Storing data in the form of DNA is an attractive way of packing huge amounts of information into a compact volume of the order of the cell nucleus, invented by nature itself. However, ordinary DNA is easily degraded, and mirror DNA is much better protected. The Chinese found that ordinary DNA placed in the water from the Beijing lotus Pond was completely destroyed in a day, while the mirror DNA continued to be determined there in a year at almost the same level.

In addition to data storage, mirror DNA can be used for labeling goods, including food, for monitoring medical implants, when creating medicines, etc.

Vaccines against RSV

If 2020 passed under the sign of the coronavirus vaccine race, now a similar situation is observed with respect to the respiratory syncytial virus (RSV). "XX2 century" wrote about the success of antibody prevention of this virus in newborns, in whom it is one of the main reasons for hospitalization.

This year, several pharmaceutical giants have switched to phase three research at once. Previously, attempts to create vaccines ended in failure: vaccines created in the 1960s led to the deterioration of diseases, in the 2010s the failure of Novavax followed (but she doesn't give up trying). Now GlaxoSmithKline, Pfizer, J&J and Sanofi in partnership with AstraZeneca have published good results. Thus, the J&J vaccine proved to be 80% effective in people over 65 in phase 2. Pfizer and GSK are also developing vaccines for the immunization of pregnant women, which transmit antibodies against the virus to the fetus through the placenta. Pfizer's vaccine has already shown 85% efficacy in phase 2b.

Modern vaccines are built taking into account the failures of previous ones: the immunogenic agent here is the RSV F protein, stabilized in the conformation preceding fusion with the cell (prefusion) (Fig. 4).

Figure 4. RSV F protein in conformation before fusion with the cell membrane (left) and after (right). The blue, red and pink colors show mutations that stabilize the prefusion conformation. Turquoise and green show the binding sites of antibodies. Yellow, gray and dark gray are three chains of protein. Source.

By mid-2022, we should find out whether such good performance results will be confirmed in Phase 3 studies, where tens of thousands of people will participate.

WHO estimates the incidence of RSV at 64 million cases, and mortality at 160,000 cases per year, this is the most common cause of viral pneumonia in children and the elderly.

Type 1 Diabetes: Will stem cells help?

Type 1 diabetes is an incurable autoimmune disease in which the immune system attacks the beta cells of the pancreatic islets that produce insulin. Patients are dependent on insulin injections for life, must constantly measure glucose levels and follow a diet. Lack of insulin leads to an increase in glucose levels, which causes damage to the kidneys, eyes, nerves and other organs. Excess insulin leads to hypoglycemia, leading to coma and even death.

Some patients with type 1 diabetes can be cured by transplanting islet cells from deceased donors, but such a source is unreliable, the operation is not shown to everyone and involves risks, therefore it is carried out quite rarely. So, from 1999 to 2015, only 1086 people worldwide underwent such a procedure, while there are millions of patients with type 1 diabetes.

Attempts to replace the donor material with cells grown in the laboratory have been made repeatedly. So, the company In 2014, ViaCyte began a clinical study of implanting a device containing pancreatic cell precursors under the skin of patients. The cells were derived from embryonic stem cells. However, the cells were not long-lived enough to provide the necessary levels of insulin.

It is all the more significant that almost 100 years after the first injection of insulin to a diabetic (January 1922) the best results of stem cell administration to date have been published, so far, however, only to one patient, and so far only for a follow-up period of three months. But the results are really impressive: the patient was diagnosed 40 years ago, in the last year before therapy he had five episodes of life-threatening hypoglycemia, and after one injection of company cells Vertex insulin demand decreased by 91% and the level of glycated hemoglobin dropped from 8.6 to 7.2% (doctors note that this is an outstanding result).

Figure 5. A vial with insulin-producing cells. Source.

This success was achieved thanks to an increasingly deep understanding of the processes of differentiation of stem cells into beta cells of pancreatic islets and the ability to control these processes at the molecular level.

It is clear that the results are still very early, but they make it possible to continue the research — 17 people were included in the first phase. Also in 2022 , the company Vertex (known as the developer of cystic fibrosis drugs, but, as we see, not limited to this success) will begin a clinical trial with encapsulated cells, which will probably help to get rid of the need to use immunosuppressive drugs before the introduction of cells.

Instant Pacemaker

Figure 6. Diagram of the device installation on the myocardium. Source.

Some patients do not require the installation of a permanent pacemaker, but a temporary one, for example, when the cause of a heart rhythm disorder is potentially reversible or when the installation of a permanent pacemaker is planned later. Now, electrodes connected to an external device are inserted into the heart of patients. After 3-7 days, they are removed, which entails the risk of infections, tissue and vascular damage, thrombosis. And the wires themselves create inconvenience and carry the risk of disconnection.

Scientists from the USA have developed a biodegradable flexible device without batteries and wires with a thickness of only 250 microns (Fig. 6). It receives energy from an external wireless device, on the same principle as RFID tags. The pacemaker consists of a polymer PLGA (poly(lactide-co-glycolide)), a magnesium-tungsten antenna, a diode on a silicone nanomembrane and a wax of vegetable origin. All these components dissolve and are excreted without residue after a maximum of 7 weeks. The device was tested on mice, rats, rabbits, dogs and human heart preparations, where it showed the ability to maintain heart rate and biocompatibility.

Butterfly disease — Herpes virus comes to the rescue

Epidermolysis bullosa, popularly known as butterfly disease, is a group of diseases in which the skin and mucous membranes are detached. The resulting bubbles and erosion zones have increased sensitivity, vulnerability and vulnerability to infections. One of the subtypes of the disease — dystrophic epidermolysis bullosa — is caused by a defect in the gene encoding collagen 7, one of the main components of the skin. Collagen-7 provides a strong connection between the epidermis and the underlying layers of cells, and its deficiency leads to skin detachment, changes in nails and teeth, damage to the epithelium of the esophagus, the genitourinary system and a significant decrease in the quality of life. Mostly patients die in childhood from incurable infections. At the moment there is no effective therapy for this disease, all treatment is symptomatic. There are isolated attempts to transplant genetically modified skin to patients, as the "XX2 century" previously wrote, but this is a very complex and piece-by-piece procedure.

Cream is quite another matter. Krystal Biotech has published the results of a study on 31 patients of its gene therapy, which is applied to damaged areas of the skin. Krystal gene therapy is unusual: most of the currently existing gene therapeutics use adeno-associated viruses to deliver genes in vivo (that is, in the patient's body). Krystal's approach is original in that the company used the herpes virus as a vector (a means of delivering the collagen-7 gene). An ingenious solution — after all, everyone knows that herpes affects just the skin cells and very well evades the immune response, which allows you to dose it many times. Krystal therapy includes, of course, not a full-fledged herpes virus, but a replicatively incompetent one that is unable to reproduce, but can only deliver the collagen-7 gene to the epidermis cells once (Fig. 7).

Figure 7. A vector based on the herpes virus enters the cell, begins the production of collagen-7, which forms fibrils connecting the outer layers of the skin with the inner ones. Source — presentation of Krystal Biotech.

The result was very good: 67% of the wounds treated with the drug were completely closed after 6 months, while in the control of such wounds there were only 22%. The next question that we will get an answer to only in 2022 is how long this effect will last and whether it will help from chronic wounds (wounds can be recurrent, which then appear, then disappear, and chronic). In any case, this is the only effective and convenient therapy in development — other options involve intradermal injections or biopsy followed by gene modification and transplantation.

In addition, dystrophic epidermolysis bullosa accounts for only 5% of all cases of epidermolysis bullosa, although these are the most severe patients. In the future, such developments are likely to allow the treatment of other hereditary skin diseases.

Do I need to read the DNA of five hundred thousand people?

One of the important practical and scientific goals of genomics is to find out the purpose of each gene in the human genome. In addition to purely fundamental questions (why do you have such an eye color and what is your tendency to read popular science articles, a joke), this information is needed to develop new drugs and approaches to the prevention and treatment of diseases. The traditional way to figure out the functions of genes is to turn them off one at a time in mice and see how their phenotype changes. Unfortunately, mice are not small furry people, so it would be nice to conduct such experiments directly on humans, but this is unethical. Fortunately, nature conducts them for us. Due to spontaneous mutations in humans, some genes are turned off every now and then (this is called a knockout) — it is important to collect information about which ones and what they affect.

British scientists sequenced the exomes (a set of exons, that is, all sections of genes encoding proteins) of 454,787 people and found 915,289 gene variants that seriously disrupted the function of the protein they encoded. After comparison with the data of medical records, 564 genes affecting medical indicators were identified. Some connections were obvious and well-known for a long time, such as the connection of COLA1A (encodes one of the types of collagen) with impaired bone formation or the connection of PCSK9 with a reduced risk of hypercholesterolemia. Other genes have been identified for the first time — for example, knockout SLC9A3R2 reduces the risk of diabetes by 20%, and knockout SLC27A3 reduces the risk of asthma by 35%. This makes it possible in the future to try to influence such genes with the help of new drug candidates.

The project was supported by the UK Biobank center and a consortium of pharmaceutical companies (Bristol-Myers Squibb, Regeneron, Biogen, Takeda, Abbvie, Alnylam, AstraZeneca, Pfizer), about $ 100 million has been spent on it since 2006.

Scientists have calculated that in order to determine the function of all genes in general, at least 5 million exomes need to be sequenced, but given the growing power of sequencing, this may take only a few years. Meanwhile, it took almost 20 years to go from one exome to 500,000.

Myasthenia gravis and the neonatal receptor

Myasthenia gravis is a rare autoimmune disease, the main symptom of which is gradually progressive muscle weakness, which in half of the patients manifests first as eyelid weakness (half—closed eyes, the so-called ptosis). In some patients, the respiratory muscles are affected, which can lead to respiratory failure.

In myasthenia gravis, antibodies attack acetylcholine receptors in the synaptic cleft of the neuromuscular junction (see Figure 8).

Figure 8. The signal to the muscle goes from the brain along the axon of the nerve cell (top) and, when it reaches the end of the axon, causes the release of the contents of vesicles containing the neurotransmitter acetylcholine. Neurotransmitter molecules cross the synaptic cleft and bind to acetylcholine receptors (AchR), which leads to a contraction of muscle fibers. In patients with myasthenia gravis, due to an autoimmune attack, the number of receptors decreases, and the muscles are unable to fully contract. Source.

Some patients are helped by acetylcholinesterase inhibitors, which raise the concentration of the neurotransmitter acetylcholine in the synaptic cleft, but most require immunosuppressants that non-specifically inhibit immunity, reducing the production of antibodies. They cause unpleasant undesirable side effects and do not help everyone.

argenX has developed a completely new immunotherapy that can be suitable for the treatment of not only myasthenia gravis, but also other autoimmune diseases. Efgartigimod is an Fc fragment of an antibody optimized for binding to the FcRn receptor (neonatal Fc receptor). If we schematically imagine an antibody in the form of the letter Y, then the Fc fragment is its "leg", and the antigen recognition sites are located at the upper ends of this letter Y. The Fc fragment serves to bind antibodies to cells of the immune system, which then perform functions, for example, to destroy pathogens. But on the cells of the endothelium (the inner surface of blood vessels) there are special FcRn receptors that can also bind the Fc fragment. They are called neonatal, because in newborns they serve to transfer antibodies from the mother's milk to the baby. And in adults, they return antibodies from endothelial cells back into the bloodstream, thereby prolonging their circulation period (Fig. 9).

Figure 9. Neonatal FcRn receptor (yellow) extends the half-life of IgG antibodies (red-gray) from about 5 to 21 days (left). Efgartigimod (blue) binds to FcRn and competes with IgG antibodies, reducing their half-life. Source.

Efgartigimod binds to FcRn, blocks its binding to antibodies and thereby accelerates their excretion from the body. In a study on patients with myasthenia gravis, it caused improvement in 67% of patients, whereas in the placebo group there were 29.7% of such patients. argenX's drug is the first registered drug with such a mechanism of action, but UCB and J&J products are coming on its heels.

Drugs with this mechanism of action are being investigated for such autoimmune indications as primary immune thrombocytopenia, common pemphigus, chronic inflammatory demyelinating polyneuropathy, thyroid eye disease and others. Each of the diseases is quite rare, but if successful, they will help a lot of patients in total and will become megablockbusters (sales of more than $ 10 billion a year).

Other drugs approved by the FDA

• In total, the FDA approved 50 new drugs in 2021, as well as 5 vaccines and two new cell therapies, which is quite at the level of previous years. Let's tell you more about some new products.

• Anifrolumab, a new drug for the treatment of systemic lupus erythematosus, has been approved for the first time in 10 years ("XX2 century" wrote about it earlier).

• Despite numerous attempts to create an effective cure for dry eye syndrome, almost all of them fail. However, even if the drug shows effectiveness in clinical trials, it is not always expected to be successful in the market — Kala Pharmaceuticals, which "XX2 century" has already written about, cannot achieve significant sales in any way. However, the need for new drugs remains, and Oyster Point has recently received approval for a new drug: the nasal formulation of varencycline. This drug, a derivative of a substance from broom, has long been used to help people quit smoking — it affects the same receptors of the central nervous system as nicotine, but not as much. It would seem, what does dry eye syndrome have to do with it? However, it turned out that the excitation of these receptors through the nose stimulates the lacrimal glands. Studies on more than 1,000 people have shown that half of them have increased tear production compared to 14-28% in the control group. Let's see if the company will be able to commercialize its drug.

• An anti-asthma antibody binding the TSLP protein has been approved for the first time. It is a signaling protein (cytokine) that plays an important role in the pathogenesis of asthma. Tezepelumab (AstraZeneca/Amgen) significantly reduced the number of worsening of the disease in patients with severe asthma. This is the first antibody that is prescribed regardless of the phenotype: previous registered biologics were limited to eosinophilic or allergic varieties of asthma.

• For a long time, proteins of the RAS family (in particular, KRAS) they were considered inaccessible to medicines — undruggable. For KRAS, for 30 years after its discovery in 1982, they could not find a suitable inhibitor, because the molecules, roughly speaking, had nowhere to connect — the protein lacks deep "pockets". Since 2013, a number of scientific successes have led to the development of KRAS inhibitors, and in 2019 they entered clinical trials. The year 2021 was marked by the registration of Amgen's Lumakras drug, which showed good results in patients with a certain type of lung cancer. There is still a lot of work ahead: the first molecules are suitable for a small number of patients and the level of responses to therapy may also be higher (now 36% of patients have a tumor reduced by at least 30%). Studies of new drugs and combinations are needed to improve the situation.

• Another drug acting on the mechanism of RNA interference has been approved - Novartis' inclisiran. This time, the disease for which he is being treated is not as rare as for previous drugs. Its target group is patients with elevated levels of LDL—C (the so-called "bad cholesterol"), which is not controlled by statins. Such people have an increased risk of heart attacks and strokes, and there are many of them. The target of the drug is well known — it is PCSK9, which the "XX2 century" has written about more than once. However, the existing drugs Repatha (Amgen) and Praluent (Sanofi) are antibodies that are injected once a month. The new drug is administered twice a year and reduces LDL-C by 50%. True, data on the impact on mortality will be available around 2026, but analysts believe that even without them, the demand for the drug will be considerable.

• The new drug for pre—contact HIV prevention cabotegravir (Viiv Healthcare), which is injected every two months, is a big step forward compared to the existing Truvada, which involves taking a pill once a day. For many people at risk for HIV, this is a much more convenient option — skipping the pill reduces the effectiveness of prevention. In direct comparative studies, cabotegravir surpassed Truvada in efficiency by 70-90%.

• The dubious approval of Aduhelm "XX2 century" has already been reported. Now you can add that the company Biogen has not achieved success in terms of sales of the drug: from June to October, they amounted to $ 2 million, which is 8.5 times less than expected. As a result, the director of science was dismissed with a scandal, the company is awaiting restructuring, and the price of the drug was halved — from $ 56,000 to $ 28,000.

• Finally, the cell therapy of multiple myeloma (CAR-T), which the XX2 century talked about last year, has been approved.

This concludes our review. Don't get sick in the New Year.

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