Radically different
Regeneron Pharmaceuticals will partner with Parabilis Medicines to discover and develop an initial five candidates encompassing a new form of antibody-drug conjugates aimed at challenging and historically undruggable targets, through a strategic research collaboration that could generate up to $2.3 billion-plus for the Cambridge, MA, biotech.
Regeneron will marry its antibody capabilities with Parabilis’ stabilized helical peptide or Helicon
platform, to develop both Antibody-Helicon Conjugates (AHCs) as well as stand-alone therapies based on Helicons—stabilized, cell-penetrant alpha-helical peptides designed to engage intracellular protein targets, including flat surfaces that are not well suited to traditional small molecule binding.
While ADCs traditionally use antibodies to selectively deliver drug payloads into target cells to induce their death from within, the AHCs envisioned by Regeneron and Parabilis would combine antibody-targeted cell access with Helicon payloads designed to selectively modulate specific intracellular proteins, including some long-undruggable proteins.
“In addition to the potential of Helicons to address previously undruggable targets, the collaboration’s intent to couple Helicons to our VelocImmune® derived-antibodies so as to precisely deliver them to cells of interest represents an exciting new approach with the potential to create an entirely new therapeutic class that can span multiple therapeutic areas,” George D. Yancopoulos, MD, PhD, Regeneron’s board co-chair, president, and CSO, said in a statement.
Regeneron has agreed to pay Parabilis $125 million, consisting of a $450 million upfront payment and commitment to invest $75 million in Parabilis’ next equity financing, subject to specified conditions. Regeneron also agreed to pay Parabilis payments tied to achieving development, regulatory, and commercial milestones, as well as tiered royalties up to the low double-digits on future net sales of any approved medicines resulting from the collaboration.
With five initial targets, the collaboration agreement could generate up to approximately $2.2 billion in total milestone payments to Parabilis.
Under the terms of the agreement, additional targets may be pursued upon additional option payments from Regeneron.
Regeneron shares fell nearly 10% Monday, to $629.68, from Friday’s close of $698.25, and plateaued on Tuesday, inching up 0.1% to $630.30. The Monday drop reflected not the Parabilis deal but a clinical setback: Regeneron on Friday evening acknowledged the failure of a Phase III trial (NCT05352672) assessing two dose levels of the lymphocyte-activation gene-3 (LAG-3) inhibitor fianlimab in combination with a PD-1 inhibitor, Regeneron’s marketed drug Libtayo® (cemiplimab), as a first-line treatment for patients with previously-untreated, unresectable locally advanced or metastatic melanoma.
Fianlimab plus cemiplimab failed the trial by not reaching statistical significance for the primary endpoint of improvement in progression-free survival (PFS) compared to monotherapy with another PD-1 inhibitor, Merck & Co.’s Keytruda® (pembrolizumab), the multi-indication cancer immunotherapy, Regeneron said, in an announcement released more than four hours after the close of financial markets.
Parabilis, a privately held company which rebranded from FogPharma in 2024, rang in 2026 by announcing the closing of a $305 million Series F financing on January 8, with proceeds intended to support continued clinical development of its lead helicon peptide candidate zolucatetide (formerly FOG-001)—a first and only direct inhibitor of the elusive β-catenin:TCF interaction, according to the company—including progression toward a registrational trial in desmoid tumors and continued evaluation across genetically simple and more complex tumor types.
In March, Parabilis presented preliminary clinical data at the 11th Biennial Meeting of the International Society for Gastrointestinal Hereditary Tumors (InSiGHT) showing significant improvement in duodenal polyposis at 60 weeks in a patient with familial adenomatous polyposis (FAP) treated with zolucatetide in the company’s ongoing Phase I/II trial (NCT05919264).
The patient showed a 52.2% reduction in desmoid tumor diameter, as well as “substantial” reductions in polyp number and size compared with a pre-treatment evaluation nearly two years prior, consistent with downstaging from Spigelman stage II to stage I.
The financing, Parabilis added, will also support advancement of its targeted discovery pipeline, including its prostate cancer franchise, and additional efforts to leverage the company’s Helicon platform to unlock long-undruggable disease targets.
In addition to zolucatetide, Parabilis’ pipeline includes:
“Through our own pipeline, we have demonstrated the potential of Helicon peptides to directly inhibit or degrade several disease-driving proteins in oncology that have long been considered out of reach,” stated Mathai Mammen, MD, PhD, Parabilis’ chairman, CEO, and president. “We are thrilled to enter into a collaboration with Regeneron that builds on this foundation, combining the intracellular access and binding capabilities of our Helicons against challenging targets with antibodies from Regeneron.”
The post Regeneron, Parabilis Ink Up-to-$2.3B Antibody-Peptide Conjugate Collaboration appeared first on GEN – Genetic Engineering and Biotechnology News.
The baby chicks were shifting and starting to pip—or trying to hatch. But not from an egg.
Instead, these chickens were growing inside transparent 3D-printed plastic cups at the Dallas headquarters of Colossal Biosciences.
The biotech company today claimed it has developed a “fully artificial egg” as part of its effort to resurrect extinct avian species, including birds like the dodo and the giant moa.
But “artificial eggshell” would probably be a better description for the invention. It’s an oval-shaped printed lattice, coated inside with a special silicone-based membrane that lets in oxygen, just as a real eggshell does.
To generate birds, Colossal took recently laid chicken eggs and carefully poured their contents into the artificial shells, where they continued growing. A window on top lets researchers peek inside.
“To see them all moving around in their artificial eggs was absolutely mind blowing,” says Andrew Pask, the company’s chief biology officer. “You really feel you can grow life outside of the womb.”
Colossal was founded in 2021 with plans to use gene editing and reproductive technology to restore extinct species, including the woolly mammoth. It’s since raised more than $800 million toward what it now terms the “scalable and controllable” creation of animals.
According to Pask, the egg technology could help conserve at-risk bird species. It could also play a role in a project to re-create the extinct giant moa, a flightless 12-foot-tall bird that once lived in New Zealand and laid four-liter eggs, larger than those of any living bird.
But Colossal may be able build one that’s big enough. The company provided a photograph of a prototype 3D-printed egg so large that staff have started to call it the “salad spinner.”
The moa went extinct after canoes carrying the ancestors of the Maori arrived on New Zealand’s South Island about 750 years ago. Archeological sites showcase the birds’ bones alongside stone cutting tools—clear evidence that they were hunted.
To be clear—Colossal isn’t close to re-creating the moa. Before that could happen, scientists would need to study DNA data from old moa bones and insert thousands of genetic changes into the genome of an existing bird, something that’s still technically difficult to do—with or without an artificial egg.
Some scientists also think Colossal is taking too much credit for its artificial eggshell, which it announced in a thundering YouTube video intoning that the company has solved the “impossible question of which came first, the chicken or the egg.”
The video is pure Hollywood—it’s meant to be funny and exciting. But Colossal has a habit of antagonizing scientists by making false and exaggerated claims. Last year, for instance, the company said it had re-created the extinct dire wolf—a claim widely rejected by experts.
This time, Colossal’s fluffed-up assertion of having created the “first-ever shell-less incubation system” is what’s raising hackles among the small flock of scientists who’ve been working on the technology for years.
“Clearly an overstatement,” says Katsuya Obara, at the University of Tsukuba in Japan, who in 2024 hatched chickens from beneath transparent plastic film. “The technology here is essentially a modification of existing methods.”
In fact, Obara notes, growing birds in artificial containers goes all the way back to 1998, when another Japanese group managed to do it with quail.
What may be an advance by Colossal is the special membrane, which lets the embryo access more oxygen. Previous systems required scientists to supplement the gas—something that may not have been good for the chicks, as often some of them would fail to hatch.
The work on the artificial eggshell was carried out in Dallas by Colossal’s exogenous development team, or Exo Dev. That group is also trying to develop artificial wombs for mammals, starting with marsupials.
“We’re looking at every single facet of what’s happening during a mammalian pregnancy to unpack exactly how we then go about recapitulating that,” says Pask.
For that team, an artificial eggshell is a relatively quick and easy technical win. That’s because chickens are already an example of ex utero development. After an egg is laid, a small embryo sitting on top of the yolk starts growing, drawing nutrients from the yolk, the white, and even the shell, which provides calcium. (Colossal says it has to add ground-up calcium to the artificial eggs.)
In order to create a moa, Colossal will have to genetically alter another type of bird, changing potentially thousands of DNA letters. But so far, chickens are the only bird species that can be genetically engineered. And that’s via a tricky process of editing stem cells that produce egg and sperm. Scientists have to add or delete DNA letters from these cells and then inject them back into an egg. The resulting bird will carry the genetic changes in its gonads—and then be able to pass them on.
Pask says Colossal’s idea is that it could modify avian stem cells enough to produce moa-like sperm or eggs. But then you might have the odd situation of a chicken laying an egg with a moa embryo inside it. “You would have chickens making moa egg and moa sperm. But it’s still a chicken egg,” he says.
Helen Sang, a professor emeritus at the Roslin Institute in the United Kingdom, says she’s not sure a moa embryo could survive on the yolk of a chicken egg, given evolutionary differences. “There are significant challenges to overcome to grow an embryo of a different species in artificial eggs,” says Sang.
Just one of those is the huge size discrepancy. The amount of yolk in a chicken egg would hardly be enough to support the much larger moa chick. Yet Pask says that is exactly where the artificial egg will come in handy.
He says it may be possible to use a fine needle to slowly “put 50 yolks together to make that yolk mass much larger.”
“The chicken egg isn’t going to be big enough to support the growth of the moa through to term, to when it would normally hatch, but that’s when you could then take that egg, put it into the artificial egg environment, and then scale it up in size,” he says.
So far, Pask says, the artificial egg is working well for chickens—almost too well. “We hatched 26 chickens and then [our CEO] asked us to put the brakes on. We have too many chickens running around.”