BioNTech takes another leaf out of Daiichi playbook, paying $70M for HER3-directed ADC

BioNTech is flattering Daiichi Sankyo through imitation. Six months after picking up an Enhertu rival, the German biotech has paid $70 million upfront to MediLink Therapeutics for an antibody-drug conjugate (ADC) directed at a second receptor also targeted by Daiichi. 

Working with AstraZeneca, Daiichi has begun to realize the long-unfulfilled promise of ADCs, establishing the HER2-directed ADC Enhertu as a major product and striving to validate a second partnered program that is targeting TROP2. Daiichi kept full rights to a third ADC candidate, the HER3-directed patritumab deruxtecan.

Sat on its COVID-19 billions, BioNTech has identified ADCs, and specifically targets pursued by Daiichi, as a good use of its cash. The biotech, which is best known for its mRNA platform, paid $170 million upfront for ex-China rights to ADCs against HER2 and another target in April. 

Now, BioNTech has returned to China to add a HER3-directed ADC to its pipeline. MediLink began testing the ADC candidate in non-small cell lung cancer (NSCLC) and breast cancer late last year, building on its preclinical evidence that the ADC delivers its cytotoxic payload to tumor cells that express HER3 without causing significant toxicity to healthy tissues. 

MediLink is retaining the rights to the candidate, YL202, in China, Hong Kong and Macau while offloading the rights in the rest of the world to BioNTech. The German biotech will end up paying more than $1 billion if the ADC hits all the development, regulatory and commercial milestones covered by the deal.

How much BioNTech ultimately pays will depend, in part, on whether HER3 lives up to expectations that it could be the next major ADC target. Interest in HER3 is built on evidence that the receptor is involved in cancers of the lung and breast but validation of the target is ongoing. 

Daiichi is driving the validation work forward, with a potentially pivotal trial of its HER3 ADC set to reach primary completion in June. The study, which was previously scheduled to reach primary completion this year, is enrolling patients with EGFR-mutated NSCLC. 

Patients with EGFR mutations were excluded from the trial that supported approval of Enhertu in NSCLC, leaving an opportunity for HER3 ADCs. Daiichi has generated evidence that HER3 mediates resistance to tyrosine kinase inhibitors, such as AstraZeneca’s Tagrisso, which are the standard first-line treatment for patients with EGFR-mutated NSCLC.