Case story: CETSA for Lead Generation
Advancing Drug Discovery Against a Challenging Membrane-Associated Target

Targeting membrane-associated proteins with small molecules remains a significant hurdle in early-stage drug discovery. These proteins often require their native cellular context to maintain proper folding, localization, and functional interactions. Standard biochemical and biophysical assays cannot typically replicate these conditions, making it difficult to detect meaningful target engagement.
A client developing positive allosteric modulators of a membrane-associated enzyme linked to Alzheimer’s disease, encountered this challenge. Despite using multiple assay platforms, no evidence of in-cell engagement was observed. The client partnered with Pelago Bioscience to evaluate whether CETSA® could offer the missing mechanistic confirmation.
Two key translational questions needed to be addressed: Could CETSA demonstrate target engagement in intact cells, where other assays had failed? Could CETSA identify novel chemical matter suitable for further lead optimization? Given that target activity is dependent on native membrane localization and protein interactions, an assay system preserving the complete cellular architecture was essential.
The Solution
A CETSA assay was developed and applied directly in live, intact cells to meet these challenges. The process involved the following stages:
1. Intact-Cell Library Screening
CETSA was used to screen the client’s compound library in living cells, preserving the physiological environment necessary.
2. Hit Confirmation and Potency Determination
Initial hits were reconfirmed through independent CETSA runs and tested in full concentration–response curves to determine binding strength and specificity.
3. Comparative Assay Analysis
Hits were compared across three assay formats: CETSA in intact cells, a cell-based functional assay, and a biochemical assay using recombinant protein.
Translational Outcome
The CETSA-based approach produced several high-confidence leads. The results showed: A strong correlation between CETSA signals and outcomes from the cell-based functional assay. No correlation between CETSA data and the biochemical assay using recombinant protein. These findings demonstrated that capturing engagement required the integrity of the full cellular context. CETSA provided direct and actionable evidence where traditional methods were inadequate.
STRATEGIC INSIGHTS: This study highlights the unique value of CETSA in enabling drug discovery against complex, membrane-bound targets. By operating in a native cellular environment, CETSA identified novel lead compounds and validated their on-target activity. The client could proceed confidently, expand screening efforts to larger libraries, and reorient their lead generation strategy based on reliable, context-aware data.

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