Small nucleic acid drugs, targeting the vast market of chronic diseases

GalNAc (N-acetylglucosamine) coupling modification is currently a commonly used small nucleic acid drug delivery system.

The three siRNA drugs recently launched are all modified with GalNAc, which is covalently coupled to the 3 'end of nucleic acid in a trivalent state. GalNAc is a ligand for the asialoglycoprotein receptor (ASGPR), which can bind to ASGPR with high affinity at the nM level. Subsequently, the receptor uptake GalNAc and nucleic acid into cells through clathrin mediated endocytosis.

The advantage of GalNAc coupling modification lies in the small molecular weight of the coupled nucleic acid, which can achieve good drug distribution effect through subcutaneous injection, and the action time can last for several months. In addition, due to its efficient targeting of the liver, the required drug dosage is small and the side effects are minimal. However, due to the high specific expression of ASGPR only in liver parenchymal cells, there are tissue limitations. Liver cancer cells have a high degree of differentiation and reduced receptor expression, making them difficult to use for liver cancer treatment.

GalNAc siRNA can exert inhibitory effects for a long time.

According to research conducted by Alnylam, GalNAc siRNA conjugated compounds can quickly enter the liver through the circulatory system after subcutaneous injection, and the concentration in plasma rapidly decreases. After entering the liver, it is rapidly engulfed by liver cells through ASGPR mediation, accumulated in lysosomes, slowly released, and continuously loaded onto RISC, thereby achieving long-lasting inhibitory effects.

Medication compliance is one of the important factors affecting the treatment effectiveness of chronic diseases.

Chronic disease patients require long-term medication and have low medication adherence. According to statistics, only 25-30 out of every 100 prescribed medications can be taken correctly. One study explored the relationship between drug compliance and cardiovascular disease by analyzing the database of large health insurance companies, which is applicable to patients hospitalized due to myocardial infarction or atherosclerotic disease. According to the proportion of days covered with statins and angiotensin-converting enzyme inhibitors, patients were stratified into fully compliant (≥ 80%), partially compliant (≥ 40% to ≤ 79%), or non compliant (<40%). The results showed that the incidence of all-cause mortality, myocardial infarction, stroke, or coronary revascularization surgery was closely related to medication adherence.

Taking ATTR small nucleic acid drugs as an example, technological development enhances safety and long-term efficacy.

The currently available ATTR small nucleic acid drugs include the siRNA drug Onpattro and the ASO drug Tegseti for polyneuropathy. The siRNA drug Onpattro is encapsulated by LNP, enhancing delivery efficiency and safety; Tegseti is a chemically modified ASO that does not use a delivery system. Due to serious safety issues with the ASO drug Tegsebi, its sales in 2019 and 2020 were $42 million and $70 million respectively (Tegsebi+Waylivra combined), far lower than Onpattro's $166 million and $306 million, respectively. The two drugs approved for marketing targeting multiple neuropathic pain caused by ATTR were developed earlier, using initial modification and delivery techniques. The upgraded drugs Vutrisiran and Eplontersen, which use the new GalNAc modification for delivery, are both under development and have shown good safety and long-term efficacy in clinical trials.

Comparing the effects of patisiran and vutrisiran on reducing plasma levels of ATTR, it can be seen that vutrisiran modified with GalNAc coupling and optimized ESC+chemical modification can achieve better inhibitory effects than patisiran administered every three weeks at a frequency of once every three months. The pharmacokinetic model predicts that administering 50mg vutrisiran every 6 months or 25mg vutrisiran every 3 months may achieve a plasma TTR reduction effect similar to administering 30mg patisiran every 3 weeks. Alnylam is exploring the use of 50mg vutrisiran every six months in the HELIOS A phase III clinical trial for the treatment of ATTR-PN.

2、Half yearly approval of lipid-lowering siRNA, hot research and development of targeted cardiovascular metabolic pathway products

Cardiovascular disease is the leading cause of death worldwide.

Cardiovascular diseases (CVD) are a common disease that seriously threatens the health of humans, especially middle-aged and elderly people. According to the World Health Organization, 17.9 million people died from cardiovascular disease in 2019, accounting for 32% of all global deaths. The top two causes of death globally are ischemic heart disease and stroke, both of which are cardiovascular diseases. According to statistics from the National Cardiovascular Disease Center, the number of cardiovascular disease patients in China is about 330 million, and deaths caused by cardiovascular disease account for the top cause of death among urban and rural residents, with 46.66% in rural areas and 43.81% in urban areas, far higher than cancer. (Report source: Future Think Tank)

Statins have limited efficacy in reducing LDL-C.

Atherosclerotic cardiovascular disease (ASCVD) is the most common disease in cardiovascular system diseases, and dyslipidemia, especially the increase of low-density lipoprotein cholesterol (LDL-C) level, is the key factor leading to the occurrence/development of ASCVD. Research shows that reducing LDL-C level can effectively reduce the risk of cardiovascular disease. Currently, statins are commonly used to control the level of LDL-C and prevent atherosclerosis and cardiovascular disease, but more than 60% of patients have limited efficacy and 7% of patients do not tolerate it. In addition, statins have a "6% effect", meaning that high-dose statins only reduce cholesterol levels by 6% compared to medium dose statins, but the risk of adverse reactions increases exponentially. From the perspective of ASCVD in the United States, only 20% of patients achieved the goal of LDL-C control after statin therapy, indicating a significant unmet clinical need.

PCSK9 is a novel target for regulating LDL-C levels.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is one of the important targets involved in regulating LDL-C. When blood passes through the liver, the low-density lipoprotein receptor (LDLR) on the surface of liver cells can bind to LDL and engulf it into lysosomes for degradation. Subsequently, LDLR will cycle back to the cell surface to continue binding with new LDL-C, further reducing the level of LDL-C in plasma. PCSK9 can bind to LDLR with high affinity, leading to the endocytosis and degradation of LDLR, reducing the level of LDLR on the cell surface and causing the accumulation of LDL-C in the patient's body, increasing the risk of cardiovascular disease. Patients with familial hypercholesterolemia have acquired functional mutations in PCSK9. Therefore, reducing the expression level of PCSK9 can restore the ability of LDLR to carry LDL-C and lower LDL-C levels.

PCSK9 monoclonal antibody has poor compliance and slow sales growth.

Currently, two fully humanized monoclonal antibodies targeting PCSK9, Alirocumab and Evolocumab, were approved by the FDA in 2015, which can bind to free PCSK9 in plasma and promote its degradation. Clinical trial results have shown that these two monoclonal antibodies can reduce LDL-C levels by approximately 50-60% and lower the risk of cardiovascular disease. Due to the need for subcutaneous injection of PCSK9 monoclonal antibody every two weeks, the frequency of medication is still relatively high. The annual medication cost is about 5700 US dollars, which is more expensive compared to statins and results in poor patient compliance. Both monoclonal antibodies have experienced slow sales growth and poor market performance.

Inflisiran is expected to improve patient compliance and demonstrate a competitive advantage

On December 22, 2021, Novartis's siRNA drug Incrisiran was approved by FDA for the treatment of atherosclerotic cardiovascular disease (ASCVD).

Unlike monoclonal antibodies, Inclisiran targets PCSK9 mRNA and induces its degradation, inhibiting the expression of PCSK9 protein and thereby reducing LDL-C levels. Inclisiran is designed based on the Alnylam ESC platform and targets the liver through GalNAc technology coupling modification. It can achieve good drug distribution effect through subcutaneous injection and has a duration of action of several months.

The long-term efficacy of Inflisiran is expected to improve patient compliance. The frequency of taking statins is once daily, while monoclonal antibodies are injected subcutaneously every two weeks. In contrast, subcutaneous injection of Inclisiran every six months can achieve a good effect in reducing LDL-C, significantly reducing the frequency of medication for patients, and is expected to improve patient compliance and achieve better treatment outcomes.

Subcutaneous injection of Inclisran once every six months can sustainably and significantly reduce LDL-C levels

The approval of Incisiran was based on the results of three phase III clinical trials, in which 1561 atherosclerotic cardiovascular disease patients were recruited in ORION-10 trial and 1617 atherosclerotic cardiovascular disease risk equivalent patients were recruited in ORION-11 trial. These patients were still unable to control the increase of LDL-C after being treated with statins with a large tolerance dose. The patients were randomly assigned to receive Incisiran (284mg) or placebo at a ratio of 1:1, and were given by subcutaneous injection on the first day and the 90th day, and then every 6 months for 540 days. The ORION-9 trial recruited 482 adults with heterozygous familial hypercholesterolemia and randomly assigned them in a 1:1 ratio to receive subcutaneous injections of inclisiran (300mg) or placebo on days 1, 90, 270, and 450.

Clinical trial results have shown that subcutaneous injection of Inclisran every 6 months can significantly reduce LDL-C levels, with a 48% -52% difference in LDL-C reduction compared to placebo, demonstrating long-lasting and significant efficacy. In terms of safety, Inclisiran has good tolerability. The frequency of common adverse events in the experimental group and placebo group was similar. Drug related adverse events are mild or moderate and receive prompt treatment without sequelae. Common adverse reactions (≥ 3%) include injection site reactions, joint pain, urinary tract infections, diarrhea, bronchitis, limb pain, and difficulty breathing.

3、Small nucleic acid drugs can effectively reduce HBsAg, and combination of drugs is expected to achieve functional cure of hepatitis B

Chronic hepatitis B has a large number of infections in the world, which is closely related to the increased risk of liver cancer.

Hepatitis B (chronic hepatitis B, CHB) is an infectious disease caused by hepatitis B virus (HBV). There are about 296 million hepatitis B virus carriers worldwide (WHO), and about 80 million hepatitis B carriers in China. Most patients with hepatitis B have no symptoms at the early stage, and hepatitis, liver fibrosis and even liver cancer will gradually appear as the disease progresses.

Hepatitis B virus continuously produces viral protein by virtue of cccDNA.

HBV adheres to the surface of liver cells through low affinity receptors such as heparan sulfate and proteoglycans, and then binds to virus receptors through the preS1 region of the large envelope protein, mediating the endocytosis of the virus by cells. The viral genome rcDNA is released into the nucleus. In the nucleus, rcDNA may be transformed into covalently closed circular DNA (cccDNA) through the cell's DNA replication mechanism. CccDNA has high stability and can be maintained in the nucleus for months to years, which is the fundamental reason for the rebound of the virus after antiviral treatment. Therefore, clearing cccDNA is of decisive significance for the cure of hepatitis B. The virus uses cccDNA to transcribe multiple mRNAs of different sizes, among which 3.5kb is pre genomic RNA (pgRNA), which can reverse transcribe genomic DNA and serve as a template for encoding viral core proteins and polymerase proteins. The assembled virus secretes host cells in a budding manner to complete the replication cycle.

The efficacy of existing drugs for functional cure of hepatitis B is limited.

At present, there is still no drug that can completely cure hepatitis B. Commonly used nucleoside drugs (NA, entecavir, tenofovir, etc.) require lifelong medication and can only inhibit HBV DNA replication to alleviate inflammatory activity. It has no effect on hepatitis B virus surface antigen (HBsAg), hepatitis B integrated DNA (intDNA), nor can it clear the hepatitis B cccDNA in the liver cell nucleus. After stopping the drug, the cccDNA becomes a virus replication template again. In the case that hepatitis B cannot be cured completely, the current clinical practice first seeks to achieve functional cure of hepatitis B, that is, HBsAg and HBV DNA are continuously undetectable, HBeAg is negative, with or without HBsAg seroconversion, so as to achieve the improvement of liver inflammation and histopathology, and reduce the incidence of end-stage liver diseases, including liver cancer.

In terms of indicators, compared with partial cure, HBsAg clearance (defined as HBsAg<0.05 IU/mL) has become the core of hepatitis B functional cure. HBsAg can affect the immune function of patients, leading to liver cell necrosis and inflammation, thereby causing cirrhosis and even liver cancer. The data shows that the earlier HBsAg clearance is achieved, the lower the risk of liver cancer occurrence. After 2-5 years of long-term treatment with existing drugs, only a very low proportion of patients can achieve HBsAg seroconversion and discontinue medication. Among them, long-acting interferon is the drug of choice for the functional cure of hepatitis B, but its side effects are large, requiring patients under 60 years of age and without basic diseases, and its clinical value is limited.

Small nucleic acid drugs can effectively reduce HBsAg levels.

The cccDNA of hepatitis B virus genome can transcribe multiple RNAs of different lengths and translate them into multiple viral proteins, of which DR1 and DR2 are the same in multiple transcripts. Therefore, small nucleic acid drugs designed for this region can directly act on all mRNA transcribed by the virus and induce its degradation, exerting inhibitory effects before the production of viral proteins. After modification with GalNAc, small nucleic acid drugs can be efficiently delivered to liver tissue with good safety and tolerability.

Recently, multiple small nucleic acid candidate drugs have shown strong ability to reduce HBsAg in Phase II clinical trials. Vir Biotechnology's VIR-2218 combined with interferon can clear HBsAg, while Johnson&Johnson's JNJ-3989 has excellent data in reducing HBsAg. In addition, there are several other small nucleic acid drug products currently undergoing clinical trials.

4、Small nucleic acid antihypertensive drugs are showing their potential, with good long-term antihypertensive safety

Hypertension is one of the main risks that threaten life and health

Hypertension is a serious cardiovascular disease that significantly increases the risk of heart, brain, kidney, and other diseases, and is the leading cause of premature death worldwide. The diagnostic criteria for hypertension are measured on two different dates, with a systolic blood pressure (SBP) reading of ≥ 140 mmHg over two days and/or a diastolic blood pressure (DBP) reading of ≥ 90 mmHg over two days. It is estimated that 1.28 billion adults aged 30-79 worldwide suffer from hypertension, of which 46% of adult hypertensive patients do not know they have this disease, only 42% of hypertensive patients receive diagnosis and treatment, and only about one-fifth of hypertensive patients (21%) have their blood pressure controlled.

Traditional antihypertensive drugs target the RAAS pathway, with AGT located upstream

The renin angiotensin aldosterone system (RAAS) is a hormone pathway that can regulate long-term blood pressure and fluid balance in the body during massive blood loss or blood pressure drop. There are currently multiple antihypertensive drugs targeting the RAAS pathway, but they need to be taken orally daily, and achieving therapeutic effects requires high compliance. Angiotensinogen (AGT) is a precursor located upstream of the RAAS pathway, mainly synthesized and secreted in the liver, and is currently a highly effective site for small nucleic acid drugs.

Zilebesiran effectively inhibits the expression of AGT

Zilebesiran (ALN AGT) is an siRNA drug developed by Alnylam for the treatment of hypertension. It specifically targets the liver through GalNAc coupling modification, inhibiting the expression of AGT in liver cells while avoiding the inhibitory effect on renal AGT, thus achieving safe and effective blood pressure control. In the Phase I clinical trial, Alnylam recruited 84 hypertensive patients and divided them into a zilebesiran group and a placebo group in a 2:1 ratio. Zilebesiran was injected subcutaneously once at doses of 10mg, 25mg, 50mg, 100mg, 200mg, 400mg, and 800mg, and the 24-hour blood pressure changes of the subjects were measured at weeks 8, 12, and 24. In terms of safety, zilebesiran has good tolerability and there were no deaths or discontinuation events. The placebo group and zilebesiran group each experienced one serious adverse event, but it was not related to the drug. At week 12, plasma AGT decreased by ≥ 90% in all ≥ 100mg dose groups, and at week 24, plasma AGT decreased by>90% in the 800mg dose group.

5、Investment analysis

The core technology in the field of small nucleic acid drugs is a key investment focus.

Small nucleic acid drugs need to target specific genes to exert therapeutic effects, and this mechanism of action presents the following characteristics in this field: there are multiple companies developing related products for diseases and targets with clear pathogenic genes or mechanisms, and competition is fierce; Choosing appropriate target genes is the key to entering new disease fields, and the development of pathological mechanism research will promote the expansion of indications for small nucleic acid drugs; The trend towards platform based development is emerging, and once delivery and modification technology platforms mature, new drugs can be rapidly developed by modifying nucleic acid sequences.

The core and technology in the field of small nucleic acid drugs are the focus of investment: the sequence of small nucleic acid drugs can be programmed, but the toxicity and delivery difficulties caused by the properties of the molecules themselves create high barriers to entry; Industry leaders have accumulated experience in multiple failed drugs and continuously carried out technological innovations. After successfully launching the first product, they gradually entered the conversion period and have begun to occupy a dominant position.

Targeting extrahepatic tissues is the key to the breakthrough of small nucleic acid drugs, and it is recommended to pay attention to the progress of new delivery technologies.

The discovery of LNP and GalNAc delivery systems has significantly improved the organ targeting and cellular uptake efficiency of small nucleic acid drugs, but it is currently limited to liver tissue. Developing delivery strategies targeting other tissues outside the liver is key to expanding the application scope of small nucleic acid drugs and further promoting the development of the field. Pulmonary drug delivery is one of the new research and development directions. The use of aerosol inhalation administration can achieve therapeutic concentrations in the lungs with good safety and tolerability, but it is still in the early stages of development. After solving the problem of lung delivery, small nucleic acid drugs are expected to be used for lung diseases such as asthma, cystic fibrosis, and infections. Currently, Ionis has two drugs, IONIS-ENAC-2.5Rx and IONIS PKK LRx, which have entered Phase 2 clinical trials, while Alnylam is still in the preclinical research and development process.

In addition to targeting the lungs through local administration, various delivery systems targeting other tissues are in the early stages of development, mainly including two approaches: first, using carriers such as liposomes, exosomes, viruses, etc. to encapsulate negatively charged nucleic acids for delivery; The second type enhances cellular uptake through ligand coupling. Ionis designed the LICA (Ligand Conjugated Antisense) platform, which connects ligands that can specifically bind to specific tissue cell surface receptors on ASO molecules, thereby achieving tissue targeted drug delivery. Arrowhead has designed the TRiMTM (Targeted RNAi Molecule) platform to develop small nucleic acid drugs targeting the liver, lungs, and tumors.

6、Introduction to Main Related Enterprises

Alnylam: siRNA leader, GalNAc revolutionizes field development

Alnylam was founded in 2002, and over the years, all four siRNA drugs currently on the market have been developed by Alnylam. At present, it focuses on genetic diseases, cardiovascular diseases, liver infectious diseases and nervous system/eye diseases, and its indications are selected to match the advantages of small nucleic acid drugs. Alnylam has multiple core technologies in the siRNA field and actively develops innovative delivery systems.

Update the fifth generation siRNA chemical modification platform, continuously improve stability and affinity, reduce off target probability, prolong action time, and achieve the effect of reducing dosage and mitigating side effects. The GalNAc bio coupled delivery system efficiently targets the liver, greatly expanding the range of liver related indications. Alnylam has chosen to first tackle diseases with clear pathogenic mechanisms in the liver system based on its own advantageous technology platform, with an overall research and development success rate of 64.3%. It is expected to launch 1-2 products annually.

Ionis: Focused on ASO drug research and development, with a wide range of indications and leading advantages

Ionis was founded in 1989, focusing on the research and development of ASO drugs. It has developed and launched 5 ASO drugs (2 of which have been delisted). Research pipeline: There are 36 products in the clinical stage, involving cardiovascular and renal metabolic diseases, neurological/eye diseases, liver infection diseases, lung diseases, and cancer. Products in the late stage of clinical practice are targeted at ATTR, metabolic diseases, and neurodegenerative diseases. Select indications based on ASO characteristics and layout reasonably.

Core technologies: including Gen2+and Gen2.5, as well as second-generation chemical modification techniques, continuously improve drug inhibition efficacy and prolong persistence. The LICA platform targeting different tissues through receptors is also under development.

Tengshengbao medicine: comprehensive anti infection layout, small nucleic acid combined with therapeutic vaccine, exploring a new mechanism for curing hepatitis B

Tengshengbo Pharmaceutical was founded in 2017, headquartered in China and the United States, dedicated to the research and development of therapies for major infectious diseases (such as HBV, HIV, MDR/XDR Gram negative bacterial infections, COVID-19) and other diseases with significant public health burdens (such as CNS diseases). For the treatment of chronic hepatitis B, the company has introduced siRNA therapy VIR-2218 from VIR, therapeutic vaccine VBI-2601 from VBI, and carried out a variety of clinical trials of combined therapy to explore the functional cure of chronic hepatitis B.

In addition to the clinical trial of VIR-2218 described above, Tengshengbao also cooperated with Vir to carry out the clinical trial of VIR-2218 combined with BRII-179 (VBI-2610) in the treatment of chronic hepatitis B. Currently, it is in phase II, and the first patient will be given in April 2021.

BRII-179 is a therapeutic vaccine based on recombinant proteins, containing Sci-B-Vac, a third-generation preventive vaccine for VBI® The same recombinant protein components and different aluminum adjuvants used in vaccines. It is composed of all three HBV surface antigens (PreS1, PreS2 and S), and has powerful T cell and B cell adjuvant, which is expected to break through the immune tolerance against HBV and achieve the functional cure of chronic hepatitis B.

Shengnuo Pharmaceutical: Delivery system peptide nanoparticles that can simultaneously regulate dual targets

Shengnuo Pharmaceutical was founded in 2007 and has a self-developed small nucleic acid delivery platform with global intellectual property rights.

Research pipeline: covering tumors, liver diseases, skin diseases, etc. Among them, STP705 has entered Phase 2 clinical trials in the United States, adopting two siRNA strategies targeting TGF - β 1 and Cox-2 simultaneously. The use of intratumoral injection to target tumor tissue requires clinical trial data to support its efficacy and safety.

Technology platform: Using a peptide nanoparticle delivery system, small nucleic acids are encapsulated with essential amino acids histidine and lysine, ensuring safety and stability after entering the human body, and effectively inhibiting target genes. In addition, it can simultaneously deliver multiple small nucleic acids targeting different targets, which can inhibit multiple genes at once and has mechanism advantages.