Three-specific antibodies advance into post-clinical cold thinking.

About 100 dual-specific antibodies are currently in clinical development, and drug developers are still trying to add more functionality to the ever-expanding antibody "toolbox."
such as Sanofi are highly interested in multisexual antibody candidates that can bind to multiple therapeutic targets and are evaluating whether multisexual antibodies can be used in cancer and infectious diseases.
, Sanofi advanced its second trisexual antibody, SAR442257, to clinical level.
other trisexual antibody programs around the world are also moving steadily forward (see table below): GT Biopharma earlier this year pushed its Trisexual Natural Killer (NK) GTB-3550 to a Phase I/II trial for the treatment of malignant tumors in the high-risk blood system.
Innate Pharma is working on a trisexual NK cell bridger for cancer treatment.
Molecular Therapeutics is planning to develop its multisexual antibody drug for the treatment of COVID-19.
in recent years, several companies, including Numab Therapeutics, have reported preclinical data on multisexual immunocellular bridgers.
photo source: Nature reviews drug discovery from HIV to tumor Sanofi's first attempt at trisexual antibodies to focus on HIV.
Gary Nabel, chief scientific officer of Sanofi, explains: "We studied HIV, which is a good proof of concept.
" Nabel team has identified a large number of antibodies that can kill HIV.
HIV mutates quickly and quickly escapes the mutation, limiting the clinical use of monotherapy.
Nabel says mono-resistant cocktail therapies could theoretically be used to counter the emergence of drug resistance, but face huge obstacles in their actual development - toxicology and pharmacodynamic evaluation of each antibody will significantly increase preclinical workload.
regulators often require each antibody to be tested individually or jointly, leading to some inso-practical and expensive trials.
production and quality control requirements present challenges for them.
, trisexual antibodies provide a simplified strategy.
is a very realistic reason to consider developing trisexual antibodies," said Nabel, a research and development group.
" his team reported in the journal Science in 2017 that a three-specific antibody, SAR441236, was able to bind independently to three different epiteases of the HIV envelope, giving non-human primates complete immunity to the ape-like HIV mix.
the project's main candidate drug, SAR441236, entered Phase I trials in April.
the discovery and optimization of this antibody, Nabel's enthusiasm for applying trisexual antibodies to other diseases has also been stimulated.
, Nabel found that trisexual antibodies have pharmacogenetic properties consistent with typical antibodies, giving the team confidence that the drugs are likely to play the desired role in humans.
, on the other hand, new drug discovery and production preparation techniques are already up to the task.
Sanofi even found that trisexual antibodies produced better than dual-specific antibodies.
from a production point of view, this is a big deal because it means we are now able to produce the drugs we need at a more cost-effective cost," said Nabel.
" Sanofi's second trisexual antibody project, SAR442257, shows the potential of these drugs in tumor immunology applications.
now, drug developers have accepted dual-specific antibodies that link T-cells to tumor cells, which help activate immune cells and bring them closer to cancer cells, ideally to ease the condition.
FDA approved the groundbreaking T-cell bridger, Amgen's CD3xCD19 dual-specific antibody drug blinatumomab, in 2014 for the treatment of acute lymphoblastic leukemia (ALL).
, however, this dual-specific T-cell bridger still faces the challenge of being more toxic and has limited activity in solid tumors.
for Sanofi, CD3xCD28xCD38 trisexual antibody SAR442257 provides a viable strategy.
T cells in a silent state require at least two signal events to activate, Sanofi's approach is to design an antibody that binds to CD3 and CD28 on T cells, while providing activation and costration signals.
and CD38 is highly expressed in multiple myeloma cells, directing T cells to myeloma cells, as well as certain lymphoma and leukemia cells.
's CD38 single-drug daratumumab has confirmed the potential of this target, with some analysts predicting that daratumumab's sales will peak at $10 billion.
Phase I trial of SAR442257 began recruiting patients in August.
On SAR441236 and SAR442257, Paul Parren, chief executive of Lava Therapeutics, said: "I look forward to seeing the future development of these drug molecules.
the scientific basis for both is reasonable.
" but Parren, who is committed to the development of daratumumab, expressed concern about their safety.
combination of the drug with CD3 is associated with cytokine release syndrome, blinatumomab's drug label carries a black box warning.
concerns can be traced back to TeGenero's CD28-specific agonic antibody TGN1412 trial in 2006.
the trial, cytokine release syndrome resulted in the hospitalization of all six subjects and led to multi-organ dysfunction in four of them.
because CD38 is widely expressed in many types of cells, this increases the risk that this trisexual T-cell bridger will attack healthy cells.
, Nabel believes clinical trials of trisexual antibodies can be conducted safely.
classical antibodies have two binding bits for each target, and Sanofi's three specific antibodies have only one binding point for each target.
, the total binding strength or affinity of trisexuality is thousands of times lower than that of a typical antibody drug.
what we need to do is minimize the off-target effect and maximize specificity," explains Nabel.
when Sanofi again analyzed the adverse cytokine storm reactions of TGN 1412, they found that a single CD28-specific antibody did not produce toxic signals.
the toxicity of SAR445257 to non-human primates is also acceptable.
Sanofi is also exploring other ways to control toxicity, including alternative routes and cycles.
Eric Vivier, chief scientific officer of NK Cell Innate Pharma, and colleagues plan to use trisexual antibodies to release the anti-cancer activity of NK cells.
NK cells are a class of innocular immune cells characterized by the ability to quickly identify and eliminate threats.
Vivier speculates that since NK cells are distributed at one-tenth the rate of T cells, NK bridging may be more secure than T-cell bridging devices.
Vivier and colleagues focused on NKp46 and CD16, which are key members involved in NK cell biolithing.
NKp46 is a glycoprotein, expressed in the immunocellular subpopular group, which is particularly important for NK cell function.
"NKp46 is by far the most specific active NK cell subject known," Vivier said.
CD16 is expressed on a wider range of immune cells, but it plays a key role in NK-mediated antibody-dependent cell-mediated cytotoxicity (ADCC).
, the two targets are supposed to work well together.
preclinical data confirm this.
a paper published last year in cell magazine, Vivier's team tested the activity of various NK bridging combinations.
these cells are either recruited through NKp46 alone or through both NKp46 and CD16, and bind to cancer cells through CD19, CD20, or EGFR.
antibodies are active, while trisexual antibodies perform better.
combined with NKp46 and CD16, it can basically increase the effectiveness by 1,000 times," said Vivier, who is the president of the NKp46.
" Innate is now working with AstraZenecom to develop three-specific and multisexual drug candidates based on NKp46.
Vivier speculates that candidates who can combine more than one cancer antigen may benefit from higher specificity.
Innate is also working with Sanofi to develop dual-specific antibodies based on NKp46.
has not yet disclosed a timetable for the progress of these NK bridges.
but Vivier was pleased with the progress, saying: "At this stage, we don't see any disadvantages in the development of the trisexual bridge."
" cocktail therapy instead? In some cases, antibody combination therapy may perform as well or better as multisexual antibodies.
just as Sanofi is bringing its three-specific T-cell bridger to clinical use, Regeneron is preparing to test a two-specific antibody combination strategy to achieve similar immunotherapy results.
, senior director of cancer immunology at Regeneron, said: "Despite growing interest in trisomynical immune cell bridgers, cocktail therapy may have similar or better results.
earlier this year, his team demonstrated how dual-specific antibodies combined with CD3 and CD28 can be combined to jointly stimulate T-cells.
report, published in Science Translational Medicine, said the combination of these drugs works better than monotherapy and avoids the risk of CD28-related cytokine release syndrome.
for Skokos, this combination method is more flexible than trisexual antibodies.
, for example, Sanofi's SAR442257, the company had to predetermine the CD3/CD28/CD38 ratio.
if this ratio needs to be adjusted clinically? In contrast, cocktail strategies can be used to titrate measurement agents in experiments to optimize activity.
, if the sequence of costutation signals is important, researchers can change the order in which dual-specific drugs are given to find out when is most effective.
regeneron's dual-specific antibody combination therapy is close to or in the process of clinical trials.
, for example, the company plans to conduct clinical trials later this year to evaluate CD28xMUC16 dual specificity in combination with CD3xMUC16 dual specificity or its PD1 inhibitor cemiplimab in combination to treat ovarian cancer.
, Regeneron is already evaluating the efficacy of CD28xPSMA dual-specific antibodies in a joint treatment for prostate cancer with cemiplimab.
also plans to begin evaluating the efficacy of CD28xEFGR dual-specific antibody combined cemiplimab later this year.
Skokos said: "We are investing heavily in a variety of combination strategies that use our CD28 to stimulate dual-specific platforms.
"but that doesn't mean Regeneron has given up three specific antibodies.
added: "We're very interested in complex multi-targeting methods, and we're really exploring them.
, but ultimately each project needs to be evaluated based on its strengths, preclinical data, and clinical opportunities.
" in Sanofi, Nabel is also taking an empirical approach.
I don't want to give anyone the impression that we have some preference for monoantial/dual-anti/tri-resistance," he said.
" Reference: 1 s trispecific antibodies take to the clinic (Source: Nature reviews drugdiscovery) 2 s Lan Wu et al. Trispecific antibodies enhance thetherapeutic efficacy of tumor-directed T cells through T cell receptorco-stimulation. Nature Cancer (2020) 3 s Laurent Gauthier et al. Multifunctional Natural Killer CellIng Targeting NKp46 Trigger Protective Tumor Immunity. Cell (2019)