One of the most exciting recent developments is the successful expansion of Her2-targeted therapy beyond the traditionally defined Her2-positive population to include patients with "Her2-low" expression. Her2-low is defined as a tumor that expresses a low level of the Her2 protein (IHC 1+ or IHC 2+/FISH negative), which was previously treated as Her2-negative, severely limiting therapeutic options for a large cohort of patients.

The success of new-generation Antibody-Drug Conjugates (ADCs), particularly trastuzumab deruxtecan (T-DXd), in treating Her2-low breast cancer has been a clinical game-changer. These new ADCs have shown significant efficacy in this previously underserved patient population, demonstrating that their potent, targeted delivery mechanism is effective even at low levels of Her2 expression. This finding has essentially created a completely new, large patient segment that is now eligible for Her2-directed targeted therapy, opening up new avenues for treatment where none existed before.

The reclassification of Her2-low tumors and the subsequent change in treatment guidelines has profoundly altered the competitive landscape, immediately expanding the potential application and revenue base for advanced ADCs. This clinical redefinition of the Her2-targetable population is the most significant recent driver of growth and innovation across the entire oncology therapeutics industry, and is a key focus area of the Her2 Positive Breast Cancer Treatment Market.

FAQ 1: What is "Her2-low" breast cancer? Her2-low breast cancer is a subtype that expresses the Her2 protein at low levels (IHC 1+ or IHC 2+/FISH negative), which was historically classified and treated as Her2-negative.

FAQ 2: Why are Her2-low tumors now treatable with Her2-targeted therapy? New-generation Antibody-Drug Conjugates (ADCs) have proven effective in this population because their mechanism is potent enough to deliver a therapeutic dose even when targeting low numbers of Her2 receptors on the cell surface.