The ocular toxicity seen with the folate-targeted ADC mirvetuximab is not due to folate receptors in the eye. It is theorized to be caused by micropinocytosis, an alternative mechanism where the drug is non-specifically taken up by normal corneal cells, representing an off-target, off-tumor toxicity.
Trastuzumab deruxtecan (TDXD) and datopotamab deruxtecan (Dato-DXd) share the same cytotoxic payload, yet Dato-DXd has a much lower rate of interstitial lung disease (ILD). This indicates the toxicity is driven by the antibody-antigen interaction, not the payload itself.
Patients report a temporary, fully reversible blue-gray tint to their vision. This occurs because the drug's target, GSK, is present in eye photoreceptors. Rather than a major concern, this manageable 'nuisance side effect' serves as a real-time biological marker that the drug is successfully engaging its target systemically.
Different TROP2-targeted ADCs using the same class of payload (topo-1 inhibitor) display distinct primary toxicities, such as diarrhea versus stomatitis. This highlights that subtle differences in drug-to-antibody ratio and linker technology create unique pharmacological profiles, making the drugs clinically distinct despite their apparent similarities.
To overcome on-target, off-tumor toxicity, LabGenius designs antibodies that act like biological computers. These molecules "sample" the density of target receptors on a cell's surface and are engineered to activate and kill only when a specific threshold is met, distinguishing high-expression cancer cells from low-expression healthy cells.
Patients whose ovarian cancer progresses on the folate-targeted ADC mirvetuximab may still respond to a subsequent folate-targeted ADC with a different cytotoxic payload. This suggests that the folate receptor alpha target remains viable and that resistance may be payload-specific, opening new sequencing strategies.
Unlike older antibody-drug conjugates (ADCs), newer agents are designed so their chemotherapy payload can diffuse out of the target cell and kill nearby tumor cells that may not even express the target antigen. This "bystander effect" significantly enhances their anti-tumor activity.
Despite both being Trop-2 targeted antibody-drug conjugates, Sacituzumab Govitecan and Datopotomab duroxotein have distinct side effects due to different linkers and payloads. Sacituzumab causes neutropenia and diarrhea, while Datopotomab is linked to stomatitis and ocular issues, requiring unique management strategies.
The differing efficacy and toxicity profiles of TROP2 ADCs like sacituzumab govitecan and Dato-DXD suggest that the drug's linker and payload metabolism are crucial determinants of clinical outcome. This indicates that focusing solely on the target antigen is an oversimplification of ADC design and performance.
Clinicians should avoid directly comparing the toxicity profiles of new ADCs, as the data often comes from different trial stages. A drug in a Phase 1 expansion cohort may appear more toxic than one with mature Phase 2 randomized data, making definitive safety assessments premature.
The ADC Dato-DXD causes high rates of stomatitis and dry eye that are difficult to treat once they appear. Effective management requires aggressive, proactive prevention from the start of therapy using steroid mouthwash and lubricating eye drops, demanding significant patient engagement and vigilance.