Therapeutic Alternatives to Recombinant Biologics: Mechanistic Framework, Clinical Evidence, and Selection Guidance

Abstract

Introduction

Recombinant biologics have transformed modern medicine but face persistent limitations, including high costs ($24,000–500,000 annually), injection burden, immunogenicity, manufacturing complexity ($200–500M in facility investments), and global barriers that limit access for billions worldwide. These challenges drive an urgent need for therapeutic alternatives.

Areas Covered

We evaluate six primary alternative modalities across FDA- and EMA-approved agents and pipeline candidates (2014–2025): oral small molecules targeting intracellular pathways, RNA therapeutics using gene silencing, CD36-mediated protein degraders (PROTACs), pharmacological chaperones, substrate-reduction therapies, and oral peptide formulations []. Clinical evidence from multiple FDA approvals demonstrates successful substitution: fitusiran achieves an 84–91% reduction in bleeding, iptacopan provides 61% transfusion independence, and deucravacitinib achieves 58.7% PASI-75 response. We identify four mechanistic principles—pathway convergence targeting, functional mimicry, allosteric modulation, and tissue-selective approaches—that can guide recombinant drug substitutions. Manufacturing analysis reveals potential for substantial cost advantages, although actual patient access requires policy intervention beyond market forces.

Expert Opinion

Therapeutic alternatives represent a fundamental evolution in pharmaceutical medicine, with molecular targets rather than modalities determining potential. Success requires a mechanistic understanding, precision patient selection using pharmacogenomics (CYP2D6, CD36 expression), and modality-specific monitoring. While mRNA-based protein replacement currently faces dosing control challenges that limit its suitability for chronic diseases, advances in self-amplifying mRNA and modRNA with controllable expression kinetics may address these limitations. The future landscape will feature complementary modality use optimized for clinical scenarios, with AI-driven discovery and personalized selection potentially improving response rates from 30% to 60% to over 80%. Global access requires technology transfer, regulatory harmonization, and value-based pricing to bridge the gap between manufacturing cost advantages and realized patient benefits.

Plain Language Summary

Biologic medicines—complex proteins produced in living cells—have revolutionized treatment for conditions such as rheumatoid arthritis, cancer, and rare genetic diseases. However, these drugs are expensive (often $25,000–$500,000 per year), require injections or infusions, need refrigeration, and remain inaccessible to billions of people worldwide due to cost and infrastructure limitations. This review examines newer drug types that can replace biologics while offering essential advantages: many can be taken as pills, are easier to manufacture, more stable, and potentially more affordable. These alternatives include JAK inhibitors for inflammatory diseases, RNA-based therapies that silence disease-causing genes, drugs that help the body dispose of harmful proteins, and treatments that stabilize malfunctioning enzymes. We identify four scientific strategies that enable these substitutions: targeting shared cellular pathways rather than individual proteins, mimicking natural body processes, using novel drug-binding sites for greater precision, and designing drugs that concentrate in diseased tissues while sparing others. Clinical trials show that these alternatives can match or exceed the effectiveness of biologics—for example, achieving 60–90% improvement in bleeding disorders and skin conditions. While manufacturing costs are lower, patient prices often remain high, highlighting the need for policy changes to improve global access. These therapeutic alternatives represent a fundamental shift toward more accessible precision medicine.

Introduction

Historical Perspective and Current Landscape

Recombinant DNA technology fundamentally transformed modern medicine, beginning with the FDA approval of recombinant human insulin in 1982.1 The subsequent expansion of erythropoietin (1989), interferons (1990s), clotting factors, and therapeutic monoclonal antibodies, beginning with rituximab (1997), validated biologics’ transformative potential across diverse therapeutic areas.2–5 Hundreds of biologic products have received FDA approval, including monoclonal antibodies targeting pathways from immune checkpoints to growth factors, recombinant proteins replacing deficient endogenous proteins, and numerous vaccines and gene therapies.1

The global biologics market continues to expand rapidly, yet access remains limited to a small fraction of patients, particularly in low- and middle-income countries.6,7 This paradox—enormous market value concentrated in a small patient population—reflects high therapeutic value for severe conditions, alongside economic barriers that restrict access. Average development costs reach $2.6 billion with 12- to 15-year timelines, creating substantial barriers to entry and contributing to high prices.8

Unmet Needs Driving Alternative Development

According to estimates from the United Nations and WHO, a substantial majority of the global population has limited or no access to biological drugs, with approximately 1 billion people lacking access to essential biologics such as vaccines.9,10 Low- and middle-income countries (LMICs), which bear the majority of the global disease burden, have access to only a minority of biologic therapies. Access patterns follow economic gradients: high-income countries achieve broad access through insurance coverage; upper-middle-income countries face moderate access barriers; lower-middle-income and low-income countries experience severely constrained access, particularly for newer therapies.11

Parenteral administration creates burdens beyond injection discomfort. Most biologics require subcutaneous injection or intravenous infusion due to their large molecular size (50–150 kDa for antibodies) and susceptibility to gastrointestinal degradation.12 Patient surveys identify injection burden as a primary concern, with up to 40% of chronic disease patients citing injection-related factors for non-adherence, and 20–30% experiencing injection anxiety.13

Immunogenicity affects a variable proportion of patients receiving biologics, with anti-drug antibodies (ADAs) potentially compromising therapeutic safety and efficacy.13,14 The incidence varies widely by product and patient population. Recent modeling suggests a majority of patients may experience some degree of ADA-driven exposure loss.15 Clinical consequences include loss of efficacy, hypersensitivity reactions (5–10% mild; 0.1–1% anaphylaxis), immune complex disease, and rare cross-reactivity with endogenous proteins.

Manufacturing complexity presents additional challenges. Production typically requires mammalian cell culture, with Chinese hamster ovary (CHO) cells used for approximately 70% of approved biologics.9 Downstream processing represents 50–80% of manufacturing costs. Capital investment requirements of $200 million to $1 billion for commercial facilities create substantial barriers to market entry. Thermostability requirements (2–8°C storage) further complicate global distribution, particularly in resource-limited settings.16

Conceptual Framework

Defining Therapeutic Alternatives

We define therapeutic alternatives as agents meeting three essential criteria distinguishing them from biosimilars, biobetters, or reformulations:

1. Different molecular structure or modality from reference biologics—not biosimilar versions, PEGylated variants, or subcutaneous reformulations of intravenous biologics.

2. Achievement of similar or superior clinical endpoints through mechanistically distinct biological approaches validated in controlled trials.

3. Addressing at least one major limitation of biologics, including administration route, immunogenicity, manufacturing complexity, cold chain requirements, or global access barriers.

This definition explicitly excludes biosimilars (structurally similar versions demonstrating comparable quality, safety, and efficacy), biobetters (improved versions through glycoengineering, PEGylation, or Fc modifications), and reformulations (alternative delivery forms of identical biologics).

Scope Clarification

This review focuses on alternatives to recombinant therapeutic proteins (antibodies, cytokines, enzymes, clotting factors). We exclude historical modality transitions predating the biologic era (eg, interferon to direct-acting antivirals for hepatitis C) as these represent sequential therapeutic advances rather than contemporary alternatives.

Classification Framework

Therapeutic alternatives encompass six major categories differentiated by molecular structure, mechanism of action, delivery characteristics, and therapeutic applications. Progress has resulted from convergent advances across medicinal chemistry, structural biology (including cryo-electron microscopy, which provides atomic-level understanding), drug delivery technologies, and molecular knowledge of disease pathophysiology, revealing convergent pathways and alternative intervention points (Figure 1).

Figure 1.

Therapeutic Modality Substitution Framework. A flow diagram illustrating how recombinant biologics map onto alternative modalities, including RNA therapeutics, oral small molecules, pharmacological chaperones, substrate-reduction therapies, and oral peptides, with emphasis on patient convenience and clinical outcomes. Solid arrows indicate established substitution pathways with FDA/EMA-approved agents; dashed arrows indicate investigational or emerging pathways. Box colors differentiate biologic modalities (blue) from alternative modalities (green).

Abbreviations: ERT, enzyme replacement therapy; GalNAc, N-acetylgalactosamine; HIF-PHI, hypoxia-inducible factor prolyl hydroxylase inhibitor; PROTAC, proteolysis-targeting chimera; siRNA, small interfering RNA; SRT, substrate reduction therapy.

Key regulatory milestones include eliglustat (2014), oral semaglutide (2019), risdiplam (2020), daprodustat (2023), iptacopan (2023), fitusiran (2025), and olezarsen (2024), demonstrating accelerating approvals for alternative modalities.

Mechanistic Classes of Alternatives

Oral Small Molecules (JAK/TYK2 Inhibitors)

Oral small-molecule inhibitors that match or exceed the efficacy of injectable biologics represent a significant pharmaceutical advance, unlike biologics, which are restricted to extracellular proteins or cell-surface receptors. Small molecules (typically <500 Da) can penetrate cells via passive diffusion or active transport to modulate intracellular signaling pathways, transcription factors, and metabolic enzymes.17 This expands the druggable genome from approximately 3,000 extracellular and cell-surface proteins accessible to biologics to over 20,000 intracellular proteins.

JAK Inhibitors: Promise and Pitfalls

The Janus kinase (JAK) inhibitor class represents both promise and pitfalls in developing oral alternatives. The JAK-STAT pathway serves as a convergent signaling node for over 50 cytokines and growth factors, including interleukins, interferons, and colony-stimulating factors.18 By inhibiting JAK enzymes intracellularly, these drugs simultaneously block signaling from multiple cytokines—TNF superfamily members, interleukin-2 family cytokines, interleukin-6 family, interferons, and growth factors—offering theoretical advantages over biologics targeting individual cytokines.

Clinical trials validated efficacy across multiple indications. Tofacitinib achieved ACR20 response rates of 59.8% at 5 mg BID and 65.7% at 10 mg BID in rheumatoid arthritis. Upadacitinib demonstrated superiority to adalimumab, with 29% achieving clinical remission versus 18% for adalimumab (p < 0.001) in SELECT-COMPARE.19,20

However, the ORAL Surveillance post-marketing safety trial fundamentally changed risk-benefit assessment. This trial randomized 4,362 rheumatoid arthritis patients aged 50 years or older with at least one cardiovascular risk factor to tofacitinib or a TNF inhibitor. Results revealed increased risks: major adverse cardiovascular events (HR 1.33, 95% CI 0.91–1.94), malignancy excluding non-melanoma skin cancer (HR 1.48, 95% CI 1.04–2.09), venous thromboembolism (HR 2.32, 95% CI 1.14–4.74), and serious infections (HR 1.17, 95% CI 0.95–1.45). These findings led to black-box warnings and restrictions on second-line use after TNF inhibitor failure.21

Ultra-Selective TYK2 Inhibitors

Safety concerns with first-generation JAK inhibitors spurred the development of more selective approaches. TYK2 emerged as an attractive target based on human genetic validation—loss-of-function TYK2 variants protect against psoriasis (OR 0.61), inflammatory bowel disease (OR 0.73), and rheumatoid arthritis (OR 0.76)—without causing severe immunodeficiency.

Deucravacitinib represents a mechanistic breakthrough by allosterically inhibiting the TYK2 pseudokinase domain rather than through competitive ATP binding. This achieves 87-fold selectivity over JAK1, greater than 200-fold over JAK2, and greater than 400-fold over JAK3 at therapeutic concentrations.22 Binding to a unique allosteric site locks TYK2 in an inactive conformation, preventing signal transduction regardless of ATP concentration. The POETYK PSO-1 and PSO-2 trials demonstrated a PASI-75 response rate of 58.7% at week 16, with no cardiovascular, thrombotic, severe infection, or malignancy signals through 2 years of follow-up, supporting first-line positioning.

Zasocitinib (TAK-279) achieved greater than 1,000,000-fold selectivity for TYK2 over JAK1 through AI-assisted structure-based drug design. Machine learning algorithms trained on kinase-inhibitor structures predicted modifications enhancing TYK2 binding while eliminating JAK interactions. Phase 2 trials demonstrated 67% PASI-75 response at week 12, with greater than 90% daily target inhibition and no safety signals.23

RNA Therapeutics (siRNA, ASO)

RNA-based therapeutics have evolved from experimental concepts to clinically validated treatments, achieving previously unattainable therapeutic outcomes.24

Mechanisms and Chemical Modifications

Small interfering RNA (siRNA) utilizes the RNA-induced silencing complex (RISC) for post-transcriptional gene silencing. The 21- to 23-nucleotide double-stranded RNA molecules are recognized by Argonaute proteins, which cleave and discard the passenger strand while retaining the guide strand to direct RISC to complementary mRNA sequences for degradation.25

Antisense oligonucleotides (ASOs) are single-stranded DNA or RNA molecules of 15–25 nucleotides that bind complementary mRNA through Watson–Crick base pairing. Mechanisms include RNase H-mediated degradation, steric blocking of ribosome assembly, and modulation of splicing. ASOs can increase or decrease protein expression depending on design.

Chemical modifications addressing critical barriers include: phosphorothioate backbone modifications improving nuclease resistance 100- to 1,000-fold and extending half-life from minutes to days; 2′-O-methyl, 2′-O-methoxyethyl, and 2′-fluoro substitutions preventing 2′-hydroxyl-mediated cleavage; and locked nucleic acid (LNA) modifications enhancing binding affinity with 1–3°C melting temperature increase per modification.25

Delivery Technologies and Clinical Success

N-acetylgalactosamine (GalNAc) conjugation revolutionized hepatocyte delivery. Triantennary GalNAc binds the asialoglycoprotein receptor with subnanomolar affinity (Kd ~1 nM), achieving greater than 90% hepatocyte uptake within 30 minutes following subcutaneous administration. The receptor, expressed at approximately 500,000 copies per hepatocyte, undergoes rapid recycling (t½ ~10 minutes), allowing repeated dosing without saturation.26

Inclisiran exemplifies successful clinical translation. This GalNAc-conjugated siRNA targeting PCSK9 mRNA achieved 50–52% LDL-C reduction in the ORION-10 and ORION-11 trials (3,178 patients), with consistent LDL-C reductions maintained between twice-yearly doses, addressing adherence challenges. The ongoing ORION-4 cardiovascular outcomes trial (15,000 patients) is evaluating effects on major adverse cardiovascular events.27

Fitusiran demonstrates RNA therapeutics’ ability to address diseases through novel mechanisms. This GalNAc-conjugated siRNA suppresses antithrombin production by 75–80%, rebalancing the coagulation cascade in hemophilia rather than replacing deficient factors. The Phase 3 ATLAS program demonstrated 84.2% and 78.9% reductions in bleeding in hemophilia A and B, respectively, with 66% of inhibitor patients experiencing no bleeding episodes. FDA approval as Qfitlia (March 2025) marked the first siRNA for hemophilia, with dosing as infrequent as six injections annually.28,29

PROTACs and CD36-Mediated Uptake

Proteolysis-targeting chimeras (PROTACs) enable targeted degradation of disease-causing proteins through the ubiquitin-proteasome system. These heterobifunctional molecules consist of a target protein ligand, an E3 ubiquitin ligase ligand (most commonly cereblon or VHL), and an optimized linker.30–33

Mechanism and Advantages

Unlike traditional inhibitors requiring stoichiometric binding and continuous target engagement, PROTACs exhibit catalytic activity, enabling single molecules to degrade multiple target proteins. Upon simultaneous binding, PROTACs induce proximity-driven ubiquitination by forming a ternary complex that brings the target and E3 ligase within ~10 Å. Following target ubiquitination, the PROTAC dissociates to catalyze additional degradation cycles.

This mechanism offers unique advantages: degradation of proteins lacking enzymatic activity, overcoming resistance mutations, achieving efficacy at substoichiometric concentrations, and eliminating protein function rather than partial inhibition.

Delivery Challenges and CD36 Discovery

PROTACs face substantial delivery challenges due to beyond-rule-of-5 (bRo5) properties. With molecular weights typically 800–1,200 Da, 8–15 hydrogen bond donors/acceptors, and poor membrane permeability (<1 × 10⁻⁶ cm/s in Caco-2 assays), many show less than 1% oral bioavailability.34–36

The identification of CD36 as a receptor facilitating PROTAC internalization in specific cell types represents a significant advance in understanding cellular entry mechanisms. Through CRISPR screens, proteomics, and cellular thermal shift assays, researchers discovered that CD36, a scavenger receptor traditionally associated with fatty acid transport, binds diverse PROTACs in cell lines with high CD36 expression.36 In these CD36-expressing cells, CD36 binds PROTACs at the cell surface (Kd 2–8 μM), triggering clathrin-dependent endocytosis. In tested cell types, CD36 expression correlates with PROTAC accumulation and therapeutic response (r² = 0.82), suggesting potential as a predictive biomarker, though generalizability across tissue types requires further investigation.

Prodrug strategies have achieved remarkable improvements: chemical modifications introducing charged or lipophilic groups enhanced CD36 affinity from ~8 μM to 2.7 μM, resulting in greater than 20-fold increased cellular uptake, 1,300-fold improved aqueous solubility, and 16-fold improved in vivo potency without increased toxicity.37

Clinical progress validates the approach. ARV-110, targeting the androgen receptor, showed PSA reductions greater than 50% in 46% of patients with T878/H875 mutations conferring enzalutamide resistance. ARV-471, targeting estrogen receptor, achieved a 40% clinical benefit rate in heavily pretreated ER+/HER2- breast cancer. Over 20 PROTACs are currently in clinical trials.

Pharmacological Chaperones and Substrate Reduction Therapies

These approaches represent conceptual evolution from symptom management to disease modification, addressing root molecular causes rather than replacing deficient proteins.

Pharmacological Chaperones

Pharmacological chaperones selectively bind and stabilize misfolded proteins, enabling them to escape endoplasmic reticulum quality control and traffic to their site of action. This addresses diseases where 30–60% of mutations cause protein misfolding rather than complete loss of function, affecting an estimated 4,000 genetic diseases.38,39

Migalastat for Fabry disease exemplifies successful development. Fabry disease results from α-galactosidase A deficiency, causing globotriaosylceramide accumulation leading to renal failure, cardiomyopathy, and stroke. Enzyme replacement therapy requires biweekly infusions costing more than $300,000 annually, with 40–90% of patients developing neutralizing antibodies. Migalastat binds reversibly to the active site with 40 nM affinity, stabilizing amenable mutations. In lysosomes, acidic pH and high substrate concentration promote dissociation, allowing catalysis.

The ATTRACT trial comparing migalastat to ERT showed an annualized eGFR change of −0.30 mL/min/1.73 m² with migalastat versus −1.03 mL/min/1.73 m² with ERT, meeting the non-inferiority criterion. Long-term extension through 8.6 years demonstrates sustained renal stabilization (mean eGFR slope −0.93 mL/min/1.73 m²/year), cardiac improvement (left ventricular mass index reduction 7.7 g/m²), and stable neurological function.38,40 Migalastat’s ability to potentially cross the blood-brain barrier and avoid immunogenicity by enhancing the patient’s own enzyme provides additional advantages.

Limitations include a restriction to 35–50% of patients with amenable mutations that retain catalytic activity.

Substrate Reduction Therapy

Substrate reduction therapy inhibits the synthesis of accumulating substrates, addressing pathology at its source. This strategy suits diseases where substrate production can be reduced without eliminating essential functions and where residual enzyme activity (even 1–5%) can handle reduced substrate load.

Eliglustat for Gaucher disease type 1 exemplifies success. Gaucher disease results from glucocerebrosidase deficiency, leading to glucocerebroside accumulation in macrophages, causing hepatosplenomegaly, cytopenias, and skeletal disease. While enzyme replacement with imiglucerase succeeds, it requires biweekly infusions, costs more than $200,000 annually, and inadequately addresses skeletal manifestations (4–8 years for improvement).

Eliglustat inhibits glucosylceramide synthase with an IC50 of 24 ng/mL, reducing substrate production by ~75%. The ENGAGE trial showed that 84% of eliglustat patients, compared with 94% on imiglucerase, achieved composite endpoints, meeting the non-inferiority criterion. The ENCORE trial demonstrated that 85% of patients stable on ERT maintained stability after switching to eliglustat.41

Long-term data reveal skeletal advantages: 60% reduction in bone marrow infiltration by MRI, 9.5% increase in lumbar spine bone mineral density, and 40% reduction in CCL18 bone biomarker—outcomes exceeding typical ERT responses, possibly due to better bone penetration of small molecules.

As a P-glycoprotein substrate, eliglustat shows minimal CNS penetration (brain: plasma <0.01), avoiding potential neurologic effects while achieving therapeutic concentrations in affected organs. CYP2D6 polymorphisms affect dosing: extensive metabolizers (50% of the population) require 84 mg BID, intermediate metabolizers (40%) need 84 mg QD, while poor metabolizers (5–10%) are excluded due to excessive exposure risk.

Oral Peptide Systems

Oral formulations for peptides traditionally requiring injection represent a triumph of pharmaceutical technology. Peptides face multiple barriers: enzymatic degradation that destroys more than 99% before absorption, poor membrane permeability due to molecular size and charge, and first-pass metabolism that eliminates 50–90% of absorbed peptide.12

SNAC Technology for Oral Semaglutide

SNAC (sodium N-[8-(2-hydroxybenzoyl)amino]caprylate) functions through multiple synergistic mechanisms. Local pH buffering raises gastric pH from 2–3 to 6–7 near the tablet, reducing pepsin activity. Transient permeability enhancement occurs through SNAC interaction with epithelial membranes, temporarily fluidizing the membrane for 30–60 minutes and increasing transcellular permeability 5- to 10-fold without disrupting tight junctions.42

The technology achieves 0.4–1% oral bioavailability, requiring 7–14 mg oral doses for exposure equivalent to 0.5–1 mg subcutaneous—sufficient given semaglutide’s high potency (EC50 ~0.1 nM) and 7-day half-life from albumin binding.

Clinical validation through the PIONEER program demonstrated HbA1c reductions of 0.6–1.4% and weight loss of 2.6–4.4 kg, comparable to subcutaneous GLP-1 agonists. PIONEER 6 (n=3,183) showed non-inferiority for major adverse cardiovascular events (HR 0.79, 95% CI 0.57–1.11).43

Emerging Technologies

Multiple innovative approaches are expanding the capabilities of oral peptides. Permeation enhancer-based ionogels combining ionic liquids with penetration enhancers have demonstrated 10–30% insulin bioavailability in preclinical models, with Phase 2 trials underway.44 Cell-penetrating peptides facilitating membrane translocation show promise for insulin, GLP-1 analogs, and small proteins less than 10 kDa. Clinical development is accelerating with oral insulin candidates exhibiting 2–5% bioavailability.

Mechanistic Principles

The transition from recombinant biologics to alternative therapeutic modalities is enabled by four distinct mechanistic principles that exploit different aspects of cellular signaling and pharmacology (Figure 2). Panel A illustrates pathway-convergence targeting, in which biologics such as adalimumab or tocilizumab neutralize specific extracellular cytokines (TNF-α, IL-6), achieving selective but limited pathway modulation. In contrast, JAK inhibitors intercept the shared intracellular JAK-STAT signaling node through which multiple cytokine receptors converge, thereby simultaneously modulating more than 50 cytokine pathways with a single oral agent. Panel B depicts functional mimicry, comparing direct protein replacement (recombinant erythropoietin activating EPO receptors) with physiologic induction via HIF-prolyl hydroxylase inhibitors (HIF-PHIs). By stabilizing HIF-2α, these oral agents trigger coordinated transcriptional responses—endogenous EPO production, transferrin receptor upregulation, and hepcidin suppression—recapitulating the body’s natural erythropoietic response rather than supplying supraphysiologic exogenous protein. Panel C contrasts ATP-competitive inhibition, where first-generation JAK inhibitors compete with millimolar intracellular ATP concentrations at highly conserved catalytic sites (resulting in poor kinase selectivity across JAK1/2/3), with allosteric modulation exemplified by deucravacitinib, which binds a unique regulatory site in the TYK2 pseudokinase domain. This allosteric binding locks the catalytic domain in an inactive conformation independent of ATP concentration, achieving greater than 200-fold selectivity for TYK2 over other JAK family members. Panel D demonstrates tissue-selective targeting by comparing intravenous enzyme replacement therapy (ERT), which distributes systemically with suboptimal penetration into bone and other target tissues, with eliglustat, an oral substrate-reduction therapy whose tissue distribution is shaped by P-gp-mediated efflux. This transporter-mediated selectivity excludes eliglustat from the central nervous system (brain: plasma ratio <0.01) while permitting 10- to 20-fold accumulation in the liver, 5- to 10-fold in the spleen, and 2- to 5-fold in the bone marrow—precisely the tissues most affected in Gaucher disease. Together, these four principles provide a mechanistic framework for identifying which recombinant biologics may be amenable to oral or otherwise simplified therapeutic alternatives (Figure 2).

Figure 2.

Four Mechanistic Principles Enabling Therapeutic Substitution of Recombinant Biologics. (A) Pathway Convergence Targeting: Biologics (Adalimumab, tocilizumab) neutralize specific extracellular cytokines, whereas JAK inhibitors intercept the shared intracellular JAK-STAT signaling node. Arrows indicate cytokine signaling direction; the cross symbol (❌) denotes points of therapeutic blockade. (B) Functional Mimicry: Recombinant erythropoietin directly activates EPO receptors (left), while HIF-PHIs stabilize HIF-2α to trigger coordinated transcriptional responses (right). The plus symbol (+) indicates upregulation of downstream targets. (C) Allosteric Modulation: First-generation JAK inhibitors compete with ATP at the conserved catalytic site (left), whereas deucravacitinib binds an allosteric regulatory site in the TYK2 pseudokinase domain (right), achieving enhanced selectivity. Dashed circles indicate binding sites. (D) Tissue-Selective Targeting: Intravenous ERT distributes systemically with suboptimal tissue penetration (left); eliglustat achieves selective tissue accumulation via P-gp-mediated efflux (right). Fold-accumulation values are shown for each target tissue.

Abbreviations: EPO, erythropoietin; ERT, enzyme replacement therapy; HIF-PHI, hypoxia-inducible factor prolyl hydroxylase inhibitor; JAK, Janus kinase; P-gp, P-glycoprotein; STAT, signal transducer and activator of transcription; TYK2, tyrosine kinase 2.

Pathway Convergence Targeting

Most successful chemical alternatives achieve therapeutic benefit by targeting convergent signaling nodes downstream of biologic binding sites rather than attempting to replicate protein–protein interactions. Protein–protein interfaces typically involve large, flat surfaces of 1,500–3,000 Ų with binding energy distributed across multiple contact points—characteristics incompatible with small-molecule binding, which requires deep pockets of 300–500 Ų.45

JAK inhibitors exemplify convergent pathway targeting. While adalimumab specifically blocks TNF-α or tocilizumab blocks IL-6 receptor, JAK inhibitors simultaneously modulate signaling from over 50 cytokines by targeting the intracellular JAK-STAT node. JAK1 pairs with JAK2, JAK3, or TYK2 depending on the receptor; JAK2 homodimerizes for growth factors like EPO and TPO; JAK3 exclusively pairs with JAK1 for γc cytokines; and TYK2 pairs with JAK1 or JAK2 for interferons and IL-12/23.18,20

This convergent inhibition provides advantages: simultaneous targeting of multiple inflammatory mediators, broader efficacy across heterogeneous patient populations, oral administration, avoidance of manufacturing complexity and immunogenicity, and rapid onset/offset, enabling dose titration.

Functional Mimicry and Physiologic Responses

HIF-prolyl hydroxylase inhibitors (HIF-PHIs) exemplify functional mimicry by achieving therapeutic erythropoiesis through physiological mechanisms rather than direct protein replacement. Instead of providing exogenous erythropoietin, HIF-PHIs stabilize HIF-2α, triggering coordinated transcription of erythropoietin, transferrin receptor, ferroportin, and hepcidin suppressors.

Daprodustat demonstrated non-inferiority to epoetin alfa in ASCEND-ND and ASCEND-D trials, with hemoglobin differences of 0.08–0.11 g/dL.46 Notably, HIF-PHI-treated patients required 32% less intravenous iron supplementation, reflecting improved iron mobilization and absorption. These differences translate to simplified treatment regimens, particularly for non-dialysis patients managing their disease at home.

Allosteric Modulation for Enhanced Selectivity

Allosteric modulation achieves selectivity that is difficult or impossible through orthosteric site targeting. Allosteric sites are often less conserved across protein families than active sites, and allosteric modulation can provide unique pharmacological properties, including ceiling effects, biased signaling, and synergy with endogenous ligands.

Deucravacitinib’s allosteric TYK2 inhibition demonstrates these advantages. Unlike ATP-competitive JAK inhibitors competing with millimolar ATP concentrations and struggling with selectivity due to conserved ATP-binding pockets (greater than 80% sequence identity), deucravacitinib binds a unique site in the TYK2 pseudokinase domain. This locks TYK2 in an inactive conformation regardless of ATP concentration,22 achieving 87-fold selectivity over JAK1 and greater than 200-fold over JAK2/3—eliminating off-target effects that contribute to JAK inhibitor toxicity.

Tissue-Selective Targeting

Tissue-selective targeting leverages differential expression patterns, metabolic activation, or transport mechanisms to achieve therapeutic effects in specific tissues while minimizing systemic exposure. This is valuable when target proteins have critical physiologic functions in multiple tissues where systemic inhibition would cause unacceptable toxicity.

Eliglustat demonstrates elegant tissue selectivity. As a P-glycoprotein substrate with high affinity (Km ~5 μM), eliglustat is actively effluxed from tissues with high P-gp expression. The blood–brain barrier expresses P-gp at 10- to 50-fold higher levels than peripheral tissues, resulting in brain: plasma ratios less than 0.01—therapeutically advantageous for Type 1 Gaucher disease lacking neurological involvement.41 Conversely, eliglustat achieves therapeutic concentrations in affected tissues: liver (10–20× plasma), spleen (5–10× plasma), and bone marrow (2–5× plasma).

Clinical Validation and Safety

FDA-Approved Alternatives

The regulatory approval of numerous therapeutic alternatives since 2014 (Table 1) provides clinical validation that different modalities can achieve comparable or superior outcomes while addressing specific limitations of protein therapeutics.

Table 1.

FDA-Approved Alternatives to Recombinant Biologics (2014–2025)

Disease Area	Traditional Biologic	Alternative Drug (Approval)	Clinical Evidence	Key Advantage	Dosing Comparison	Refs
Hemophilia A/B	Factor VIII/IX Q2-3D IV	Fitusiran/Qfitlia - siRNA (2025)	84–91% ABR reduction; 66% zero bleeds with inhibitors	Works despite inhibitors	6 SC/yr vs 100–180 IV	[28,29]
PNH	C5 inhibition Q2-8W IV	Iptacopan - Factor B inhibitor (Dec 2023)	+2.4 g/dL Hgb; 61% transfusion independence	Complete complement blockade	TID oral vs IV infusions	[47,48]
PNH with EVH	C5 inhibitor alone	Danicopan - Factor D add-on (2024)	Significant Hgb improvement; superior transfusion avoidance	Addresses C3-mediated hemolysis	TID oral add-on	[49]
CKD Anemia	ESA injection Q1-4W	Daprodustat - HIF-PHI (Feb 2023)	Non-inferior Hgb; 32% less IV iron	Physiologic EPO, improved iron	Daily oral vs injection	[46]
Gaucher Type 1	Imiglucerase Q2W IV	Eliglustat - SRT (2014)	84% vs 94% stability; 60% ↓ marrow infiltration	Addresses skeletal disease	BID oral vs IV	[41]
Fabry Disease	Agalsidase Q2W IV	Migalastat - chaperone (2018)	eGFR −0.30 vs −1.03; 8.6-year sustained efficacy	Stabilizes endogenous enzyme	EOD oral vs IV	[38,40]
Hypercholesterolemia	PCSK9 mAb Q2-4W SC	Inclisiran - siRNA (2021)	50–52% LDL-C reduction maintained for 6 months	Twice-yearly dosing	2 SC/yr vs 13–26 SC	[27]
Rheumatoid Arthritis	TNF inhibitor Q1-2W SC	Upadacitinib - JAK1i (2019)	29% vs 18% remission; BUT HR 1.33 MACE	Oral convenience	Daily oral vs SC	[19–21]
Psoriasis	IL-17/23 mAb Q4-12W SC	Deucravacitinib - TYK2i (2022)	PASI-75 58.7%; no CV/VTE signals	First-line positioning	Daily oral vs SC	[22]
Multiple Sclerosis	Interferon-β Q1-2D SC/IM	Fingolimod - S1P modulator (2010)	54% relapse reduction; 65–70% 2-yr persistence	Improved adherence	Daily oral vs injection	[50,51]
SMA	Nusinersen IT Q4M	Risdiplam - SMN2 modifier (2020)	Type 1: 41% sitting vs 0%; 81% alive without ventilation	CNS + peripheral distribution	Daily oral vs IT	[52,53]
Migraine Prevention	CGRP mAb Q1-3M SC	Atogepant - CGRP antagonist (2021)	56–61% ≥50% reduction; 3.7–4.2 fewer monthly days	No CV contraindications	Daily oral vs SC	[54–56]
Hypercholesterolemia	PCSK9 mAb Q2-4W SC	Bempedoic acid - ACL inhibitor (2020)	18% LDL-C reduction; 13% MACE reduction	Oral for statin-intolerant	Daily oral vs SC	[57]
HAE Prophylaxis	C1 esterase inhibitor IV	Berotralstat - kallikrein inhibitor (2020)	44% attack rate reduction	Oral daily dosing	Daily oral vs IV	[58]
Sickle Cell	Hydroxyurea	Voxelotor - HbS inhibitor (2019)	51% achieve >1 g/dL Hgb increase	Directly inhibits sickling	Daily oral	[59]

Notes: Pricing comparisons excluded from table due to heterogeneous methodologies across sources (WAC, net prices, international variation). See Section 6.1 for economic discussion.

Emerging Pipeline

Table 2 lists the late-stage pipeline alternatives as available for records.

Table 2.

Selected Late-Stage Pipeline Alternatives (Phase 2–3)

Drug Candidate	Mechanism	Indication	Phase	Clinical Evidence	Projected Timeline*	Refs
Zasocitinib (TAK-279)	Ultra-selective TYK2	Psoriasis, PsA, IBD	Phase 3	67% PASI-75 wk 12; >1M-fold selectivity	Est. 2026	[23]
Brepocitinib	Dual TYK2/JAK1	Dermatomyositis, IBD	Phase 3	VALOR trial ongoing	Est. 2026–2027	[64]
INCB086550	PD-L1 small molecule	Solid tumors	Phase 1	15% ORR; IC50 ~2 nM	Est. 2027–2028	[65]
ARV-110	PROTAC AR degrader	Prostate cancer	Phase 2	PSA >50% reduction in AR mutants	Est. 2025–2026	[37]

Notes: *Timelines are estimates based on publicly disclosed development plans and typical regulatory review periods; actual approval dates are subject to trial outcomes and regulatory decisions.

Comparative Safety Profiles

Safety profiles differ substantially across modalities, informing patient selection:

• JAK Inhibitors: First-generation agents carry class-wide warnings based on ORAL Surveillance data: increased MACE (HR 1.33), malignancy (HR 1.48), VTE (HR 2.32), and serious infections (HR 1.17). Risk stratification should consider patient age (>50 years), cardiovascular risk factors, smoking history, and prior malignancy.21

• TYK2-Selective Inhibitors: Deucravacitinib’s allosteric mechanism and selectivity translate to favorable safety—no cardiovascular, thrombotic, or severe infection signals through 2+ years in over 3,000 patients, enabling first-line use without restrictions applied to JAK inhibitors.22

• RNA Therapeutics: GalNAc-siRNA agents demonstrate favorable safety, with injection-site reactions as the primary adverse events. Hepatotoxicity concerns with earlier ASO chemistry have been mainly addressed through improved modifications.67

• PROTACs: Emerging safety data suggest target-dependent profiles. On-target toxicity (excessive degradation) and off-target degradation represent theoretical concerns being monitored in trials.37

Therapeutic Area Case Studies

Hemophilia Transformation

Fitusiran exemplifies transformation in hemophilia management. Traditional factor replacement requires 100–180 IV infusions annually for hemophilia A, resulting in a substantial treatment burden. Factor VIII inhibitors develop in 25–30% of severe hemophilia A patients, rendering standard replacement ineffective.

Fitusiran’s mechanism—reducing antithrombin to rebalance coagulation—circumvents both limitations. The Phase 3 ATLAS results demonstrated annualized bleeding rates of 1.7 (hemophilia A) and 1.4 (hemophilia B), compared with 21.8 and 15.3 on prior therapy. Among inhibitor patients, 66% achieved zero bleeding episodes—previously considered impossible.28,29

Complement System Modulation

Oral complement inhibitors have transformed the management of complement-mediated diseases. Iptacopan’s Factor B inhibition provides a more complete blockade than C5 inhibition alone. C5 inhibitors prevent the formation of the membrane attack complex but leave the C3 convertase intact, causing C3-mediated extravascular hemolysis, which explains why 75% of eculizumab-treated patients remain anemic.47

Factor B inhibition prevents the formation of the alternative pathway C3 convertase, blocking both C3 activation and downstream C5 cleavage. Clinical outcomes demonstrate superiority: mean hemoglobin increase 3.6 g/dL with iptacopan versus 1.2 g/dL historically with C5 inhibition; transfusion independence in 61% versus 20–30%; normal hemoglobin (≥12 g/dL) in 42% versus less than 10%.48

Danicopan, as an oral add-on to C5 inhibitors, demonstrates combination potential by inhibiting Factor D to address residual C3 activity while maintaining terminal complement blockade. The ALPHA trial showed a 2.4 g/dL improvement in hemoglobin when danicopan was combined with C5 inhibitors, with 50% achieving transfusion independence, versus 15% with C5 inhibitors alone.49

Economic, Manufacturing, and Access Perspectives

Manufacturing Economics versus Market Reality

Manufacturing analysis reveals a disconnect between production costs and market pricing. However, direct comparisons are complicated by methodological differences in cost reporting (wholesale acquisition cost, net price after rebates, international reference pricing) and a lack of standardized transparency.

Comparative Manufacturing Economics

Small-molecule synthesis achieves notable efficiency: production costs typically in the range of hundreds to low thousands of dollars per kilogram, yields of 60–90%, facility requirements of $50–100 million serving multiple products, and two- to three-year construction timelines. Process optimization through continuous flow chemistry has contributed to cost reductions over the past decade.8

Biologic production remains complex: costs typically tens of thousands of dollars per kilogram even at commercial scale, cell culture yields of 2–5 g/L requiring large bioreactors, dedicated facilities costing $200–500 million, four- to seven-year construction timelines, and quality control representing 20–30% of manufacturing cost.9

RNA therapeutic manufacturing occupies the middle ground: costs range from the thousands to tens of thousands per kilogram for GalNAc-siRNA, and specialized facilities cost $100–200 million. Current global capacity remains limited, potentially constraining broad access.67

Market Pricing Reality

Despite manufacturing differences, pricing shows limited correlation with production costs, reflecting value-based assessment, intellectual property protection, and market dynamics. Published analyses suggest:

• Iptacopan has been priced comparably to existing C5 inhibitors despite oral formulation and simpler synthesis, reflecting orphan drug economics where small patient populations may necessitate premium pricing regardless of manufacturing approach.48

• Eliglustat pricing approaches that of enzyme replacement therapy despite presumed lower production costs, reflecting comparable clinical value and limited competition in a small patient population.40

• Oral semaglutide commands a premium over injectable formulations despite potentially lower manufacturing and distribution costs, driven by patient preference and adherence benefits.67

• This pattern highlights that achieving global access likely requires policy intervention: value-based pricing that rewards clinical benefit, reference pricing that links reimbursement to alternatives, and differential pricing strategies.

Supply Chain and Capacity Constraints

Manufacturing capacity represents a critical bottleneck limiting patient access. For siRNA therapeutics, the global GMP capacity of ~50 kg annually is concentrated in 5 facilities. Each new facility requires an investment of $100–200 million and 18–24 months of construction.67

PROTAC manufacturing faces greater constraints with a capacity below 1,000 kg/year. Complex 15- to 25-step synthesis yielding below 5% limits efficiency, with few CDMOs possessing the required capabilities.37,66

Geographic concentration creates vulnerability. For biologics, 60% of global capacity is in the US and Europe. For small molecules, 80% of API production occurs in China and India. For RNA therapeutics, manufacturing is even more concentrated, with no significant capacity in developing countries.

Technology Transfer and Global Access

Technology transfer requirements vary dramatically by modality. Small molecules can leverage existing infrastructure ($10–50 million, 12–18 months). Biologics require new facility construction (>$200 million, 3–5 years). RNA therapeutics fall between, requiring specialized equipment but less complex facilities.11

Success models include HIV treatment, where generic production reduced costs from $10,000 to less than $100 annually. Similar models could apply to oral alternatives, with generic JAK inhibitors potentially available for less than $500 annually, compared with the current $40,000.

Innovative access models include voluntary licensing through the Medicines Patent Pool (enabling access to HIV/hepatitis C drugs in 100+ countries), differential pricing, local production partnerships, and advanced market commitments.

Future Directions

Technological Enablers

Artificial Intelligence in Drug Discovery

AI integration has transformed the development of alternative modalities. AlphaFold2 and subsequent algorithms have democratized structural biology, providing accurate 3D models for over 200 million proteins, including previously intractable targets. These predictions enable structure-based drug design without experimental structures, identification of cryptic allosteric sites, and virtual screening of billions of compounds in days rather than years.17

Zasocitinib development exemplifies AI’s impact. Machine learning models trained on kinase structures and selectivity data predicted modifications affecting TYK2 versus JAK family binding, guiding focused library synthesis rather than random screening. This achieved greater than 1,000,000-fold selectivity reportedly in reduced time compared to traditional approaches. Some companies have reported improvements in optimization timelines and clinical success rates using AI-guided methods, though systematic benchmarking data remain limited.23,68

Generative AI models now design novel molecules with desired properties, proposing structures human chemists would not typically consider. Integration with robotic synthesis platforms enables closed-loop optimization where AI designs, robots synthesize, and results feed back for iterative improvement.69,70

Delivery Innovation

Advanced delivery systems have enabled previously impossible therapeutic modalities. For RNA therapeutics, GalNAc conjugation, which achieves greater than 90% hepatocyte uptake, has transformed siRNA from a research tool to practical medicine, with 18–24-month target-to-clinic timelines versus 3–5 years for traditional drugs. Next-generation delivery includes muscle-targeting peptides, antibody conjugates for tumor-specific delivery, and engineered EVs for CNS penetration.26

For oral peptides, emerging technologies promise expansion beyond current limitations. Ionic liquid formulations with 15–20% insulin bioavailability in preclinical models could enable meal-time oral insulin. Robotic pills with microneedles inject the drug directly into the intestinal wall, achieving greater than 90% bioavailability for large proteins.44

Integrated Treatment Paradigms

The future therapeutic landscape will feature personalized selection from multiple modalities rather than universal biologic replacement:

• Acute severe disease may favor rapid-onset IV biologics, providing immediate high concentrations for conditions like cytokine storm or severe autoimmune flares.

• Maintenance therapy could use convenient oral alternatives that enable dose titration and improved adherence for chronic conditions where consistent drug levels matter more than rapid onset.

• Prevention may employ long-acting RNA therapeutics, reducing treatment burden to quarterly or biannual dosing for cardiovascular prevention or hereditary disease management.

• Salvage therapy could combine modalities targeting complementary mechanisms.

Personalized Medicine and Biomarker Selection

Multi-omic profiling will enable precision matching:

• Genomics identifies drug-metabolism variants (CYP2D6, CYP3A4), disease-causing mutations that determine chaperone amenability, and polygenic risk scores that predict response.

• Proteomics reveals pathway activation states, post-translational modifications that affect drug binding, and protein expression levels (CD36 for PROTACs), thereby determining uptake.

• Metabolomics assesses drug-processing capacity and monitors treatment response.

Machine learning models integrating multidimensional data could improve response rates from 30–60% to over 80% through optimal patient-treatment matching. Digital biomarkers from wearables could enable real-time dose adjustments.71,72

Critical Assessment and Limitations

Essential limitations warrant acknowledgment:

• Publication Bias: Negative trials are 2–3 times less likely to be published than favorable results, leading to an overly optimistic assessment. Industry-sponsored trials (>80% of late-stage development) may emphasize favorable outcomes.1

• Long-term Uncertainty: Most alternatives have a median follow-up of less than 2 years, compared with 25+ years for biologics like etanercept. Safety signals may emerge slowly, as demonstrated by JAK inhibitors, where cardiovascular effects became apparent 5 years post-launch.

• Patient Subpopulation Restrictions: Pharmacological chaperones work in only 35–50% with amenable mutations. Eliglustat’s CYP2D6 restrictions exclude ~10% of patients. CD36 expression variability affects 10–15% in specific populations. Biologics remain necessary for substantial patient populations.

• Ethnic Variations: CYP2D6 poor metabolizer prevalence ranges from 1% (East Asians) to 15% (Mediterranean populations). CD36 deficiency occurs in ~0.3% of Europeans but 10–15% of some Asian populations. Alternatives validated in predominantly European trials may differ in other populations.

Perspective on mRNA Therapeutics

While mRNA technology has revolutionized vaccine development, protein replacement therapy for chronic diseases faces challenges that limit its current suitability. The fundamental issue involves dosing predictability—unlike recombinant proteins with precise dosing or siRNA with predictable suppression, mRNA-encoded protein production depends on uncontrolled variables:

Translation efficiency varies 10- to 1,000-fold between individuals based on ribosome availability, cellular energy state, and translation factors. Cellular uptake heterogeneity creates mosaic expression patterns. mRNA stability varies based on secondary structure, cap, and poly(A) integrity, and cellular nuclease activity. Duration of expression ranges unpredictably from hours to days.66

This variability creates substantial inter-patient differences, potentially ranging from subtherapeutic to toxic, unacceptable for chronic disease requiring stable levels. However, advances in self-amplifying mRNA, modified nucleotides reducing immunogenicity, and optimized UTRs may address these limitations. Current evidence suggests caution rather than categorical exclusion.

Conclusions and Recommendations

Key Achievements

The regulatory approval of numerous therapeutic alternatives since 2014 validates that molecular targets, rather than specific modalities, determine therapeutic potential. Clinical outcomes—fitusiran’s 84–91% bleeding reduction for hemophilia, deucravacitinib’s 58.7% PASI-75 response in psoriasis, iptacopan’s 61% transfusion independence in PNH—demonstrate alternatives can match or exceed biologic efficacy while offering distinct advantages.

The mechanistic framework—pathway-convergence targeting, functional mimicry, allosteric modulation, and tissue-selective approaches—provides rational guidance that transforms drug discovery from empirical screening to mechanism-based design.

Recommendations

• For Researchers and Developers: Prioritize targets where biologics face delivery, immunogenicity, or manufacturing limitations. Apply mechanistic principles systematically. Invest in platform technologies enabling multiple products. Develop companion diagnostics for patient stratification (CD36 expression for PROTACs, pharmacogenomics for metabolism-dependent drugs, mutation screening for chaperones).

• For Policymakers and Regulators: Develop adaptive regulatory frameworks that encourage innovation while ensuring safety. Create platform designations to enable streamlined development. Harmonize international requirements. Implement value-based pricing that rewards patient benefits. Support technology transfer through investment and intellectual property frameworks, balancing innovation with access.

• For Clinicians: Maintain awareness of evolving options through continuing education emphasizing mechanisms. Develop expertise in pharmacogenomic testing interpretation. Engage patients in shared decision-making, considering preferences beyond clinical endpoints. Monitor for modality-specific adverse events with appropriate testing frequency.

• For Patients and Advocacy Groups: Advocate for access to complete treatment options. Participate in clinical trials and registries. Demand pricing transparency. Support technology transfer initiatives. Share real-world experiences through patient-reported outcome platforms.

Vision for the Future

The transformation from empirical discovery to mechanism-based design offers unprecedented opportunities. The next decade will witness:

• Hybrid modalities combining the advantages of different approaches—antibody-drug conjugates delivering small molecules, RNA-PROTAC conjugates for targeted degradation.

• AI acceleration through generative design, prediction of clinical success from preclinical data, and patient-drug matching optimization.

• Manufacturing innovations translate cost advantages to improved access through continuous manufacturing (50–70% cost reduction), modular facilities, and distributed production.

• Regulatory evolution with global harmonization, adaptive pathways, and value-based agreements.

The ultimate measure of success will be whether patients gain access to treatments that best meet their individual needs. The vision of democratized access to life-changing therapies remains the driving force. Success requires sustained stakeholder collaboration, recognition that modalities offer complementary rather than competing solutions, and a commitment to ensuring that innovation translates into improved outcomes globally. The goal is not wholesale biologic replacement but the expansion of therapeutic options, enabling personalized treatment selection and optimizing efficacy, safety, convenience, and access for each patient.

Methodology Note

This review synthesized evidence from systematic literature searches of PubMed, ClinicalTrials.gov, FDA, and EMA databases through January 2025. Search terms included combinations of “therapeutic alternatives,” “oral biologics,” “small molecule inhibitors,” “RNA therapeutics,” “PROTACs,” “pharmacological chaperones,” and specific drug names. Inclusion criteria encompassed peer-reviewed publications, regulatory documents, and conference abstracts reporting clinical outcomes for alternatives to approved biologics. Quantitative comparisons used published meta-analyses and regulatory documents.73 Cost modeling incorporated industry reports and peer-reviewed economic analyses with purchasing power parity adjustments—manufacturing assessments derived from technical reports, patent filings, and expert consultations. Expert opinions and future perspectives are clearly distinguished from evidence-based conclusions. All numerical estimates reflect conservative interpretations when ranges were available.

Funding Statement

This research received no funding from public, commercial, or not-for-profit agencies.

Data Sharing Statement

No data were used for the research described in this article.

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

The author is an advisor to the US FDA, EMA, MHRA, the US Senate, the White House, and multiple heads of sovereign states; a developer of biological drugs and their substitutes; and holds numerous patents on these drugs. The author holds equity interest in RNA Therapeutics Inc., DEI Biopharma Inc, Abyolo, BioRx Inc.