ADCs Have a Toxicity Problem. Dendrimers Don't.

Starpharma's DEP platform targets ADC toxicity at the delivery level, with a Genentech deal signaling big pharma's interest

25 Mar 2026

Antibody-drug conjugates have a seductive logic: attach a toxic payload to an antibody, guide it to a tumour, and kill cancer cells while sparing healthy ones. The reality is messier. Payloads leak into the bloodstream before reaching their target, producing toxicity spikes that cap dosing, shrink eligible patient populations, and have quietly buried more than a few promising drug programmes.

Starpharma, an Australian biotech, thinks it has a structural fix. Its DEP platform loads drug molecules onto a dendrimer carrier, a highly branched synthetic molecule, before attaching the whole construct to the targeting antibody. The result is a more uniform, heavily loaded vehicle that releases its cargo in a controlled way at the tumour site, reducing the peak blood concentrations that cause off-target damage. At the World ADC London 2026 summit in February, the company presented the platform as a direct answer to one of targeted oncology's most stubborn engineering problems.

The clinical record is modest but meaningful. Over 350 patients have been treated in DEP-based trials. One programme targeting platinum-resistant ovarian cancer has drawn encouraging signals from regulators: the FDA has indicated it would be eligible for Fast Track designation and potentially accelerated approval. HER2-targeted radiotheranostic candidates are expected to enter human trials this year.

Commercial validation arrived last September, when Genentech signed a collaboration agreement covering multiple oncology targets. Starpharma received an upfront payment of $5.5m and becomes eligible for up to $564m in milestones, plus tiered royalties. Genentech secured an exclusive worldwide licence to develop and commercialise products built on the DEP platform. For a technology that has spent years on the margins of the ADC conversation, this is a significant vote of confidence.

Starpharma has also opened the platform to outside researchers through its Star Navigator initiative, inviting drug discovery teams to test dendrimer-based delivery within their own pipelines.

The broader context matters. More than 20 ADCs have now received global regulatory approval, and investment in the field is accelerating. But toxicity remains the ceiling that prevents many of these drugs from reaching their full potential. Delivery architecture, long treated as a secondary concern, is becoming the primary battleground. If dendrimers can reliably raise that ceiling, the platform may matter as much as the payloads it carries.