AstraZeneca Acquires Caelum in $500m Deal to Strengthen Rare Diseases Division

AstraZeneca will acquire Caelum Biosciences, a rare disease drugmaker with a Phase 3 treatment for Amyloid light chain (AL) amyloidosis, in a deal worth $500 million. The UK drugmaker inherited the option to buy Caelum when it acquired Alexion in a mega buyout worth $39 billion. Alexion had bought a minority stake in Caelum in 2019. 

Now a subsidiary of AstraZeneca, Alexion will buy the remaining shares in Caelum for $150 million. It will also make future milestone payments of up to $350 million to Caelum if it meets regulatory and sales goals.  

Another beneficiary of the deal was Fortress Biotech, which founded Caelum Biosciences. Fortress will be eligible to receive approximately 43% of all proceeds from AstraZeneca’s transaction.

Thin Market for AL Amyloidosis Treatments

Amyloid light chain (AL) amyloidosis is a rare blood disorder that results in organ failure. It is caused by cancerous plasma cells that produce misfolded amyloid proteins. The abnormal proteins clump together in fibrils, accumulating in organs such as the kidneys, liver, and heart, which disrupts their function.

The rare disease currently has no cure, but treatments can stop the reproduction of abnormal plasma cells or prevent the formation of fibrils. 

The drug that has caught AstraZeneca’s attention was Caelum’s CAEL-101, an antibody that removes amyloid deposits from affected organs.

“With a median survival time of less than 18 months following diagnosis, there is an urgent need for new treatments for this devastating disease,” said Alexion CEO Marc Dunoyer. “CAEL-101 has the potential to be the first therapy to target and remove amyloid deposits from organ tissues, improve organ function, and, ultimately, lead to longer lives for these patients.” 

The drug is undergoing two Phase 3 trials that will enroll 370 patients with AL amyloidosis. CAEL-101 can be considered the most advanced clinical candidate to treat AL amyloidosis by clearing up amyloid fibrils. Only one other clinical asset is in Phase 3 — Prothena’s birtamimab.

Prothena’s anti-amyloid antibody initially failed a Phase 2b trial in 2018 and was shelved when continuation was judged futile. It was revived by the company after a second look revealed the drug improved survival for late-stage patients at the highest risk of dying.

Other treatments for AL amyloidosis attempt to address the underlying cause of the disease — abnormal plasma cells.

Johnson & Johnson’s Darzalex is one such drug. It was approved for multiple myeloma, which is closely related to AL amyloidosis, and won FDA approval as a combination therapy with chemotherapy and steroids this January to treat newly diagnosed patients with the disease. It targets CD38, a protein overexpressed in cancerous plasma cells, and induces apoptosis (programmed cell death).

Meanwhile, Takeda was not so fortunate. It had to shelve Ninlaro (ixazomib) after the drug failed to stem disease progression in patients in a Phase 3 trial. Similarly, a Phase 2 trial investigating GSK’s combination treatment (GSK2315698 + GSK2398852) was also discreetly terminated by the company after a risk assessment.

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Joy Lin

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