Following AstraZeneca’s SERENA-4 failure, both camizestrant and Roche’s giredestrant SERDs have now failed in ESR1-unselected first-line metastatic breast cancer, in sharp contrast to giredestrant's positive lidERA result in an ESR1-unselected early-stage population. We see a potential mispricing emerging between Roche and AstraZeneca, with the market potentially extrapolating lidERA into a broader commercial opportunity than is warranted while underappreciating a more practice-aligned pathway elsewhere. The core debate is whether investors should be underwriting a broad SERD backbone in early breast cancer today, or positioning for a narrower outcome with a different catalyst path into 2027 that could shift relative value across the group.