Summary of Key Points
Multiclonal antibodies (with three or more targets) once hailed as the "next generation of revolutionary therapies" are now entering a phase of "reality check." Companies like BeiGene have actively reduced their pipelines for multiclonal antibodies against solid tumors, while giants such as Amgen, Sanofi, and Roche have also abandoned some of their multiclonal projects. The main reasons are uncertain efficacy and high safety risks. The theoretical advantages of multiclonal antibodies, such as the synergistic activation of immune pathways, have not been fully realized in clinical trials, and the challenges posed by the accumulation of targets, including development difficulties and toxicity issues, have exceeded expectations. The key to competition in this field will no longer be the number of targets or the concept of being "the first in the world" but rather the ability to find a balance between efficacy, safety, and scalability to truly meet clinical needs.
1. From "First in the World" to "Pipeline Downsizing": Why Have Multiclonal Antibodies Suddenly Lost Favor?
Multiclonal antibodies were once highly sought after by pharmaceutical companies because, in theory, a single molecule could perform multiple functions such as tumor recognition, T cell recruitment, and immune activation, making them more efficient than bispecific antibodies. BeiGene even conducted the world's first clinical trial with a quadravalent antibody and claimed to be working on quintavalent and hexavalent antibodies. However, they have now removed three quadravalent antibodies against solid tumors from their pipeline, retaining only one for autoimmune diseases.
Why? The decision to abandon the "world-first" label during a critical IPO period indicates that the clinical data for these projects did not meet expectations. For example, their GNC-035 (CD3/4-1BB/PD-L1/ROR1) is theoretically capable of synergistically attacking tumors, but solid tumors are too heterogeneous (with a variety of cancer cell types and uneven distribution of targets), and the affinity for the ROR1 target is insufficient, rendering the drug ineffective. Additionally, the large size of multiclonal antibodies makes it difficult for them to penetrate tumor tissues, further reducing their efficacy.
Amgen's AMG305 and Roche's SAIL66 have also been discontinued, demonstrating that the "conceptual value" of multiclonal antibodies is being eroded by clinical realities.
2. The Deadly Gap Between Efficacy and Safety: Two Major Challenges in Multiclonal Antibody Development
For a multiclonal antibody to become a successful drug, it must overcome two major hurdles: Can it cure the disease? Will it cause harm?
1. Efficacy: Theory is Promising, but Reality is Challenging
The core idea behind multiclonal antibodies is that "1+1+1>3," but in practice, balancing the affinity, spatial structure, and metabolic rate of multiple targets is extremely difficult. BeiGene's quadravalent antibody, for instance, needs to bind to CD3 to activate T cells, PD-L1 to relieve immune inhibition, and target tumor-specific molecules—all of which must be perfectly coordinated; otherwise, the efficacy will be reduced. The heterogeneity of solid tumors adds another layer of complexity, as different cancer cells within the same tumor may have different targets, meaning that a multiclonal antibody might only be effective against some cells, limiting overall effectiveness.
2. Safety: The Risk of Immune System Overreaction
Multiclonal antibodies can strongly activate the immune system, potentially leading to a "cytokine storm"—an overactive immune response that causes fever, organ damage, or even death. Sanofi's trivalent antibody SAR442257 caused side effects in 70% of patients, with 55% experiencing cytokine storms, resulting in its termination. BeiGene's quadravalent antibody for glioma (GNC-039) had significant toxicity due to the combination of CD3 and 4-1BB in the sensitive brain environment, exceeding patient tolerance limits.
The "therapeutic window" between these two hurdles is very narrow, and many multiclonal antibodies are eliminated before they even reach the market.
3. More Targets Don't Always Mean Better: The Counter-Crowding Logic in Multiclonal Antibody Development
Pharmaceutical companies once believed that more targets meant a more powerful drug, leading to the development of six-targeted antibodies. However, it has become clear that the number of targets does not equate to clinical value.
For example, BeiGene's remaining autoimmune antibody (GNC-038) targets CD19, which is relatively specific for autoimmune diseases and thus easier to balance in terms of safety and efficacy. Roche's approach of "format follows function" emphasizes identifying the clinical problem first before designing the molecular structure. More sophisticated technologies, such as PRO-TCE (Protein-Target-Cleavage-Enabled), add a "tumor-specific switch"—the drug's activity is blocked by a masking peptide in normal tissues and only activated by tumor-specific proteases, reducing toxicity.
In summary, the competitive focus for multiclonal antibodies has shifted from the number of targets to precise design.
4. The Future: Multiclonal Antibodies Still Have Potential, but They Need to Return to Their Fundamental Purpose
Multiclonal antibodies are not useless; they can indeed address issues that monoclonal and bispecific antibodies cannot solve (such as overcoming drug resistance and precisely targeting tumors). However, the industry must move away from excessive hype and focus on the fundamental question: Can these drugs improve patients' quality of life and extend their survival?
The multiclonal antibodies that will succeed in the future will be those that:
- Target specific clinical needs (such as difficult-to-treat tumors or autoimmune diseases);
- Have clever structural designs to balance efficacy and safety (e.g., using PRO-TCE technology to reduce toxicity);
- Possess strong scalability to overcome production challenges related to mismatch, impurities, and scaling issues.
In short, the competition in the multiclonal antibody field has shifted from who can create the most complex molecules to who can develop the most practical and effective drugs.
Conclusion
The cooling of interest in multiclonal antibodies is not a bad thing; it brings the industry back to a more rational approach. As the article emphasizes, new drug development is never about showing off technology. Whether they are monoclonal, bispecific, or multiclonal, all must be validated by clinical trials. Multiclonal antibodies will still play an important role in treatment, but their value will be determined by the benefits they bring to patients.