Ann: SABRE topline results, page-36

Finally had the chance to read the announcement. Yet another Ann that screams FTD, BTD and best in class along with recent SARTATE - I would be surprised if we didn’t apply or achieve them.

Huge unmet need in GRPR. This is what our AI friend has to say.

Question: What percentage of cancers and which cancers don’t express PSA but express GRPR?

Great question! To clarify, you’re asking about cancers that do not express PSA (Prostate-Specific Antigen) but do express GRPR (Gastrin-Releasing Peptide Receptor), along with what percentage of cancers fall into that category.

PSA and GRPR Expression Overview

• PSA is primarily a marker for prostate cancer and is highly specific to prostate epithelial cells.
• GRPR is expressed in various cancers, including prostate cancer, but also in some non-prostate cancers.

Cancers That Do NOT Express PSA but Express GRPR

1. Non-Prostate Cancers with GRPR Expression
   PSA is essentially not expressed outside prostate tissue, so non-prostate cancers generally don’t express PSA but can express GRPR.
2. Common cancers known to express GRPR but not PSA include:

• Breast cancer: Many studies show GRPR is overexpressed in breast cancer cells, especially in estrogen receptor-positive subtypes.
• Lung cancer: Both small cell and non-small cell lung cancers can express GRPR.
• Gastrointestinal cancers: Pancreatic, colon, and gastric cancers have shown GRPR expression.
• Bladder cancer: Some bladder cancers express GRPR.
• Gliomas: Certain brain tumors like gliomas express GRPR but not PSA.

Percentage of Cancers Expressing GRPR but Not PSA

PSA expression outside prostate cancer is negligible, so we focus on GRPR:

• Breast cancer: GRPR expression reported in ~60-80% of cases in various studies.
• Lung cancer: GRPR expression seen in ~40-70% of cases.
• Gastrointestinal cancers: Variable, but reports suggest ~30-60% depending on subtype.
• Bladder cancer: Roughly 40-50% express GRPR.
• Gliomas: Up to ~50% show GRPR positivity.

Exact percentages vary depending on detection method (IHC, mRNA), cancer subtype, and study population.

Summary Table

	Cancer Type	PSA Expression	GRPR Expression (%) (approximate)
1	Prostate cancer	High	High
2	Breast cancer	None	60-80%
3	Lung cancer	None	40-70%
4	Gastrointestinal	None	30-60%
5	Bladder cancer	None	40-50%
6	Gliomas	None	~50%