Antibody past (1986–2000)

The history of antibodies began with the discovery of anti-sera in the 1890s by Emil von Behring and Kitasato [12], which were used as a defensive therapy for invading pathogens and therapeutics for several infections such as diphtheria, influenza, polio, scarlet fever, measles, tetanus, etc. These natural antibodies were polyclonal in nature, i.e., a mixture of antibodies produced from multiple B-cell clones, and were capable of binding to specific and non-specific targets (antigens), resulting in generating undesirable effects. Despite their limitations, these early developments laid the conceptual groundwork for what would become one of the most transformative fields in modern medicine. Later in 1975, with the invention of hybridoma technology, monoclonal antibodies (MAbs) were developed. These full-length antibodies (FL-Bodies) are Y-shaped immunoglobulins, each having two Fab regions joined to an Fc region via a flexible hinge region. The two Fab regions bind to identical epitopes on a single target antigen, making these conventional antibodies bivalent and monospecific in nature [13]. These conventional antibodies transformed the immunotherapy field and were considered as ‘magic bullets’ due to their precise target binding with high specificity. Subsequently, Köhler and Milstein [14] were awarded the Nobel Prize in 1984 for their invention of hybridoma technology and monoclonal monospecific antibodies [15]. This was not merely a scientific breakthrough, but a turning point in the philosophy of medicine, one that shifted the focus from broadly acting treatments to precision-guided therapies rooted in molecular recognition. MAbs generated with hybridoma technology were of murine origin (generated in a mouse), and thus were immunogenic to use as therapeutics for humans. This limitation was addressed by chimeric antibodies, in which murine variable regions were grafted onto constant domains of human origin antibodies. Infliximab antibody is an example of a chimeric antibody. Chimeric antibodies still have a major portion of mice origin, so this was further reduced by CDRs grafting to the human framework, resulting in humanized antibodies. Later on, complete humanized antibodies originated either by producing from transgenic animals or by producing antibodies by phage-display library, which are 100% human in nature. These fully human FL-Bodies become the gold standard with favourable tolerance, optimal pharmacokinetics in humans [7]. The therapeutic success of FL-Bodies led to more targeted and effective therapeutics and a new era of specialized medicine, where target-specific antibodies are used as a therapeutic for a variety of diseases, offering renewed hope and better patient outcomes. Muromonab (which targets the CD3 receptor on T-lymphocytes and blocks their function) became the first antibody to get approval in 1986, and was used as an immunosuppressive therapy in organ transplants [16]. Muromonab was a murine MAb, and thus it was associated with several side effects, such as cytokine release syndrome (CRS) and neurological issues, and thus it was discontinued in 2010–2011. However, the clinical therapeutic efficacy of muromonab laid the foundation for the era of antibody therapeutics. Later on, the surge in the development of new MAbs and their approval for multiple diseases promoted intense research in the antibody field [17]. This rapid progress underscored antibodies’ unmatched versatility and therapeutic relevance across a wide spectrum of clinical conditions. As of today, more than 130 different FL-Bodies have been approved by regulatory agencies in the world for various diseases ranging from infectious diseases to cancer [6]. Frag-Bodies (antibody fragments) are the truncated versions of FL-Bodies (or heavy chain antibodies which are found in Camelidae and Shark families) that retain the capacity to bind to antigen and include F(abʼ)2 (~110 kDa), Fab (~50 kDa), scFv (~25 kDa), and VHH or Nanobody (~12 kDa) [7]. Frag-Bodies are also being developed for therapeutic use. For example, Licartin, a F(abʼ)2-based Frag-Body is an immunoradioconjugate that targets the hepatocellular cancer-associated antigen (HAb18G/CD147) and was approved in 2006 by the NMPA (China) [18]. Similarly, Certolizumab-pegol, a Fab-based Frag-Body, blocks the binding of TNF-alpha to its receptor and is used as an anti-inflammatory therapy [19]. Brolucizumab, a scFv-based Frag-Body, binds to VEGF-A and inhibits neovascularization in macular degeneration disease [20]. Similarly, Caplacizumab is an anti-vWF nanobody approved for the treatment of acquired thrombotic thrombocytopenic purpura [21]. As of today, more than 40 Frag-Bodies products have been approved for various diseases. Their smaller size, improved tissue penetration, and potential for engineering multifunctional formats make Frag-Bodies a highly promising subclass in the expanding antibody landscape.

Thus, the period from the first antibody approval in 1986 to 2000 represents the ‘past era’ of therapeutic antibodies, characterized by the emergence of both FL-Bodies and Frag-Bodies, which laid the foundation for the present-day antibody-based products (Figure 1; 1986–2000). This era of antibody development also witnessed the initiation of a new field: development of FL-Body:Conjugates, a new class of antibody-based products in which FL-Body is conjugated to non-antibody drugs, viz., small chemical drugs, radioisotopes, bacterial toxins, etc., for their targeted (site-specific) delivery. A notable milestone was the approval of Gemtuzumab ozogamicin in 2000, the first FL-Body:Conjugate where an anti-CD33 IgG4 is conjugated to cytotoxic N-acetyl gamma calicheamicin drug, for the treatment of acute myeloid leukemia [22]. Collectively, this foundational era represents not only technical innovation but also marks a paradigm shift in therapeutic science, establishing the core principles of specificity and modularity that now define the era of precision medicine.

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Figure 1. Past, present, and future of therapeutic antibodies [34, 35]. FL-Body: full-length antibody; Frag-Body: antibody fragment; Poly-Body: polyspecific and polyvalent antibody.

Antibody present (2001–2026)

The success of antibodies as therapeutic agents has made them a dominant force in the biopharmaceutical field in the current world. Their market share now represents one of the fastest‑growing segments in pharma, underscoring the economic and clinical indispensability of antibodies [23, 24]. However, treatment regimens using antibodies are challenged by the realization that not only one but many pathways are involved in the pathogenesis of diseases, and there is a need to inhibit/target multiple pathways (antigens) to provide better therapeutic outcomes [25]. This prompted the development of antibodies that can bind to multiple antigens simultaneously [26], i.e., Poly-Bodies, and initiated the present era of therapeutic antibody development. Poly-Bodies are engineered antibodies that can bind to two or more different antigens simultaneously. Thus, Poly-Bodies can be bispecific, trispecific, tetraspecific, and so on. Similarly, Poly-Bodies can be polyvalent, i.e., they can have more than two binding sites for the same epitope (trivalent, tetravalent, and so on). This innovation reflects a deeper shift in therapeutic strategy from one drug-one target to a multifaceted approach that acknowledges the complexity of human diseases. Poly-Bodies have high efficacy due to high affinity and high avidity and are considered superior therapeutic options to conventional antibodies [27]. Thus, Blinatumomab (anti-CD19/CD3) became the first FDA-approved Poly-Body (polyspecific and polyvalent antibody; in 2014) [28]. Similarly, JNJ-80948543 (anti-CD3/CD79b/CD20) is a trispecific Poly-Body developed for the treatment of non-Hodgkin lymphoma patients and is currently in phase I clinical trials (NCT05424822, NCT06139406, NCT06660563) [29]. Since the approval of the first bispecific Poly-Body in 2014, an additional 14 different Poly-Bodies have been granted approval in different countries by March 2025 [7, 27]. In the last couple of years itself (2023–2024), nine different polyspecific Poly-Bodies got approval for the treatment of a variety of diseases and conditions; Glofitamab (anti-CD20/CD3), Epcoritamab (anti-CD20/CD3), Elranatamab (anti-BCMA/CD3), Talquetamab (anti-GPCR5D/CD3), Tarlatamab (anti-DLL3/CD3), Zanidatamab (anti-HER2 epitope 1/HER2 epitope 2), Zenocutuzumab (anti-HER2/HER3), Odronextamab (anti-CD20/CD3), Ivonesclmab (anti-PD-1/VEGF-A) [3, 7, 30]. Thus, the number of Poly-Bodies entering clinical trials and obtaining approval has been increasing at an exponential rate, demonstrating not only scientific advancement but a deepening of antibody utility in treating previously untreatable or refractory diseases.

The present era of antibody development (Figure 1; 2001–2026) has also witnessed the development and approval of numerous other FL-Bodies and Frag-Bodies. The era has also seen a surge in the exploration of new categories of conjugating drugs (nucleic acids, photosensitizers, cytokines, etc.), resulting in the development of newer FL-Body:Conjugates and Frag-Body:Conjugates. For example, in 2020, a photosensitizer-conjugated antibody, Cetuximab Saratolacan (anti-EGFR antibody conjugated to IRDye 700DX), was approved for the treatment of Unresectable Locally Advanced and Recurrent Head & Neck Cancer in Japan [31]. FL-Bodies offer extended half-life and Fc-mediated effector functions but suffer from poor tissue penetration. In contrast, Frag-Bodies provide superior tumor access and rapid clearance, though they lack stability and Fc-mediated immunological responses. Considering the advantages of Frag-Bodies, such as their small size, ease of design and production, and improved tissue penetration, they have become a preferred choice for conjugation. FL-Bodies typically have a half-life of 2–3 weeks, whereas Frag-Bodies, including Fab, scFv, and VHH formats, exhibit half-lives ranging from minutes to hours. This rapid clearance makes Frag-Bodies and their conjugates particularly well-suited for diagnostic applications [32, 33]. Recently, Lim et al. [34] developed a Frag-Body:Conjugate in which an anti-cMET Fab Frag-Body is conjugated to Duo5 cytotoxic drug as a potential treatment for solid tumors. Similarly, Kalinovsky et al. [35] developed anti-GD2 scFv Frag-Body:Conjugate in which anti-GD2 scFv Frag-Body is conjugated to monomethyl auristatin E for the treatment of GD2-positive solid tumors. As of today, more than 15 Frag-Body:Conjugates are in clinical trials, which will be in market in the coming years. This trend highlights not only the therapeutic flexibility of Frag-Bodies but also their increasing value in combination modalities. In contrast to FL-Bodies and Frag-Bodies, Poly-Bodies are multi-targeting, high-avidity, and have superior therapeutic efficacy. However, Poly-Bodies have a challenge of complex manufacturing and potential immunogenicity. Most approved Poly-Bodies are anti-cancer, involving T-cell engager bispecific antibodies, which have a challenge of CRS [36].

The present era of antibodies marks success for conjugated antibodies, especially in diagnostic and therapeutic treatment of cancer and suggests an exciting era of targeted, highly effective, and safer cancer treatment that promises to substitute conventional chemotherapies across various cancers [37]. Building on this progress, advances in computer-based biology, high-throughput screening technologies, and artificial intelligence have greatly accelerated the pace of antibody discovery and development, firmly establishing antibodies as a vital element of precision medicine. It is notable that, despite these remarkable advances, antibody development still faces several critical obstacles that can limit therapeutic potential. Immunogenicity remains a primary concern, as anti-drug antibody (ADA) responses can reduce therapeutic efficacy, alter pharmacokinetic properties, and, in some cases, trigger severe adverse immune reactions. The challenge is compounded by the fact that ADA development varies among patients, influenced not only by individual factors but also by geographical and racial differences. However, the major reason for ADA development is the non-human nature of antibodies for murine, chimeric, and humanized antibodies. This results in poor pharmacokinetics (fast clearance) and immunogenicity, and thus limits clinical efficacy. These interpatient variations highlight a complex obstacle in antibody therapy that still needs to be effectively addressed [38, 39]. Beyond immunogenicity and pharmacokinetic concerns, antibody therapeutics face major challenges in large-scale production, cost management, and supply sustainability. Despite their clinical success, high manufacturing costs continue to restrict accessibility, particularly in low- and middle-income countries. A substantial share of these costs arises from drug substance (DS) manufacturing, including both upstream and downstream processes. Meeting the growing and diversifying demand for antibodies also requires adequate and flexible biomanufacturing capacity. Most MAbs are produced in mammalian systems, mainly Chinese hamster ovary (CHO) cells, using large-scale bioreactors. While global capacity has expanded, imbalances persist, with some firms facing shortages and others excess capacity and financial strain. To address this, the industry increasingly relies on contract manufacturing organizations (CMOs) and single-use bioreactor technologies, which provide flexibility, rapid scalability, and lower capital investment. Moreover, emerging DS manufacturing technologies and formats are being explored to reduce costs, increase supply flexibility, and enhance development efficiency. Incorporating process economic analysis from the preclinical stage through late-stage development is also critical to evaluate feasibility, optimize manufacturing strategies, and select the most suitable production approach for each antibody program [40].

Antibody future (2027 onwards)

The clinical success of antibodies initiated a competitive environment among pharma companies and research groups. This positive competition is driving innovations in making highly efficacious and precision antibody-based products. The development of Poly-Bodies and conjugated antibodies is an example of such innovations (Figure 1; 2027 onwards). Hundreds of these next-generation products are in advanced stages of clinical trials which are going to be marketed in the coming years [41, 42]. The clinical success of Poly-Bodies and conjugated antibodies is expanding the boundaries of therapy, especially in complex diseases such as cancer and multifaceted inflammatory disorders. As clinical approvals for antibody-based products increase each year, the field is expected to grow further, providing more opportunities for diverse clinical uses.

Specificity is a crucial deciding factor for the therapeutic efficacy in the case of antibodies. The future of antibody-based products looks incredibly promising with the ongoing development of trispecific, tetraspecific, and pentaspecific antibodies. Sonelokimab (anti-interleukin (IL)-17A/IL-17F/albumin) is a trispecific antibody for hidradenitis suppurativa disease that is currently in phase 3 clinical trial (NCT07007637) and is expected to be approved in the near future [43]. Umizortamig (GNC039, anti-CD3/4-1BB/EGFRVIII/PD-L1) is a tetraspecific Poly-Body for glioma and solid tumor and is currently in a phase I clinical study (CN110831973A) [44]. Researchers are also pushing boundaries in engineering multivalent antibodies or Poly-Bodies with 10, 20, or even more binding sites which were once thought impossible. Thanks to accelerating technological advances, these ultra-multivalent antibodies may soon become a reality. The development of Poly-Body:Conjugates is also significantly advancing the antibody-based product pipeline. BL-B01D1 is a first-in-class Poly-Body:Conjugate in which an anti-EGFR/HER3 bispecific Poly-Body is conjugated to topoisomerase I inhibitor (Ed-04) and is currently in phase 3 clinical trial (NCT06118333) for recurrent or metastatic nasopharyngeal carcinoma [45]. Thus, in the future, we will see more Poly-Bodies and their immunoconjugates in the market.

Drug payload in antibody:conjugates is a crucial factor for deciding their efficacy. Rapid progress in conjugation chemistry, therapeutic payload engineering, and nanotechnology is expanding the spectrum of payloads that can be effectively conjugated to antibodies. In the future, there will be a variety of payloads such as carbon-dots [46], nanorobots [47], PROTACs (proteolysis targeting chimeras) [48], etc. This could offer new mechanisms, improved efficacy with a multi-payload strategy that further enhances the versatility and clinical potential of antibody conjugates. Moreover, the future of antibodies is being transformed by advances in genetic and protein engineering technologies [49] that enable the precise design of Poly-Bodies, their optimization with enhanced affinity and specificity, stability, pharmacokinetics, and especially the design of complex Poly-Body formats and their conjugates. With every engineering milestone, the vision of truly personalized treatments is coming closer to reality, inspiring optimism across the scientific community. Along with that, artificial intelligence and machine learning (AI/ML) are also accelerating antibody development, helping in predictive analytics, high-throughput screening of lead candidates, and ultimately shortening the antibody development timeline and enhancing the success rate [50]. AI’s role in the design of de novo antibodies and predicting their molecular behavior will reshape antibody development [51, 52]. This convergence of biology and computation is already producing candidates that would have taken years to generate by traditional means. A notable example is AU-007, a human IgG1 MAb designed using AI to bind IL-2 at its CD25 binding epitope. Developed by Aulos Bioscience, AU-007 has advanced to the Phase 2 portion of a Phase 1/2 clinical trial evaluating its efficacy in treating solid tumors. Interim results presented at the 2024 ASCO Annual Meeting demonstrated AU-007ʼs ability to harness IL-2 to reduce solid tumors, supporting ongoing and planned Phase 2 expansion cohorts in combination with low-dose aldesleukin in melanoma, renal cell carcinoma, and non-small cell lung cancer [53] (Aulos https://aulosbio.com/). While specific wet-lab validation hit rates for AU-007 are not publicly disclosed, the development of AI-designed antibodies like AU-007 exemplifies the potential of AI/ML to enhance the efficiency and success rates of antibody discovery, offering a promising alternative to traditional methods such as hybridoma technology and phage display. While AI/ML approaches have significantly accelerated antibody discovery and optimization, their application still faces important limitations. Current models rely heavily on the availability and quality of training data, which are often biased toward well-studied targets and antibody formats. As a result, predictions may not generalize reliably to novel antigens or complex multispecific architectures [54, 55]. In addition, AI-based designs frequently require extensive experimental validation, as in silico predictions do not fully capture protein folding, developability issues, immunogenicity, or in vivo behavior. Limited interpretability of some models and integration with downstream manufacturing and regulatory requirements further constrain widespread adoption [56]. Addressing these challenges will be essential for realizing the full potential of AI/ML in antibody design. The approved therapeutic antibodies, along with their format, target, clinical indication, and approval status, are summarized in Table 1.