January 15, 2026 by Alipheron

Introducing hard pharmacophore precision constraints in Pharos3D

𝐏𝐫𝐞𝐜𝐢𝐬𝐢𝐨𝐧 𝐂𝐨𝐧𝐬𝐭𝐫𝐚𝐢𝐧𝐭𝐬 𝐢𝐧 𝐕𝐢𝐫𝐭𝐮𝐚𝐥 𝐒𝐜𝐫𝐞𝐞𝐧𝐢𝐧𝐠 𝐭𝐨 𝐒𝐨𝐥𝐯𝐞 𝐟𝐨𝐫 𝐂𝐨𝐯𝐚𝐥𝐞𝐧𝐭 𝐚𝐧𝐝 𝐏𝐫𝐨𝐱𝐢𝐦𝐢𝐭𝐲-𝐈𝐧𝐝𝐮𝐜𝐞𝐝 𝐄𝐧𝐯𝐢𝐫𝐨𝐧𝐦𝐞𝐧𝐭𝐬

In the design of covalent inhibitors and bifunctional molecules (PROTACs/Glues), the geometric relationship between a fixed “warhead” or “anchor” and the rest of the scaffold is a primary determinant of success. Traditional virtual screening often struggles to balance these rigid structural requirements with the need for conformational flexibility.

In 𝐏𝐡𝐚𝐫𝐨𝐬-𝟑𝐃, we have been developing a variable approach that integrates exact structural constraints with weighted pharmacophore mapping.

𝐓𝐡𝐞 𝐃𝐞𝐬𝐢𝐠𝐧 𝐋𝐨𝐠𝐢𝐜: 𝐀 𝐂𝐚𝐬𝐞 𝐒𝐭𝐮𝐝𝐲 𝐨𝐧 𝐀𝐝𝐚𝐠𝐫𝐚𝐬𝐢𝐛 (𝐀 𝐜𝐨𝐯𝐚𝐥𝐞𝐧𝐭 𝐊𝐑𝐀𝐒 𝐆𝟏𝟐𝐂 𝐢𝐧𝐡𝐢𝐛𝐢𝐭𝐨𝐫) To identify novel leads while maintaining the essential binding mode of Adagrasib, we implemented a dual-constraint strategy:

1. 𝐒𝐭𝐫𝐢𝐜𝐭 𝐌𝐨𝐭𝐢𝐟 𝐄𝐧𝐟𝐨𝐫𝐜𝐞𝐦𝐞𝐧𝐭: The 𝐟𝐥𝐮𝐨𝐫𝐢𝐧𝐚𝐭𝐞𝐝 𝐚𝐜𝐫𝐲𝐥𝐚𝐦𝐢𝐝𝐞 warhead was defined as an “exact” requirement. By locking this motif, the search space is immediately pruned of any candidates lacking the specific geometry required for the covalent cysteine reaction.

2. 𝐒𝐜𝐚𝐟𝐟𝐨𝐥𝐝 𝐖𝐞𝐢𝐠𝐡𝐭𝐢𝐧𝐠: A high pharmacophore weight was assigned to the remainder of the (𝐒)-𝟐-(𝐏𝐢𝐩𝐞𝐫𝐚𝐳𝐢𝐧-𝟐-𝐲𝐥) 𝐚𝐜𝐞𝐭𝐨𝐧𝐢𝐭𝐫𝐢𝐥𝐞 𝐬𝐜𝐚𝐟𝐟𝐨𝐥𝐝. This allows the algorithm to prioritize candidates that satisfy the spatial vectors of the original ligand while allowing for bioisosteric exploration in the peripheral regions.

𝐈𝐦𝐩𝐚𝐜𝐭 𝐟𝐨𝐫 𝐌𝐞𝐝𝐂𝐡𝐞𝐦 & 𝐂𝐨𝐦𝐩𝐂𝐡𝐞𝐦 𝐓𝐞𝐚𝐦𝐬:

• 𝐅𝐨𝐫 𝐌𝐞𝐝𝐢𝐜𝐢𝐧𝐚𝐥 𝐂𝐡𝐞𝐦𝐢𝐬𝐭𝐬: This capability enables strategically ’locking’ validated SAR elements, while exploring novel 3D chemical space. This facilitates scaffold hopping into unexplored chemotypes that maintain essential pharmacophoric features, thereby diversifying the intellectual property portfolio and identifying novel lead series with improved physicochemical profiles.

• 𝐅𝐨𝐫 𝐂𝐨𝐦𝐩𝐮𝐭𝐚𝐭𝐢𝐨𝐧𝐚𝐥 𝐂𝐡𝐞𝐦𝐢𝐬𝐭𝐬: By reducing noise and enriching the hit list with molecules that align closely with a query’s key chemical characteristics, this method enhances the probability of determining a subset with significant interaction potential with the target. It serves as a critical pre-screening filter before advancing to computationally demanding downstream methodologies.

The graphics below illustrate configurability and a 3D overlay result from the 𝐀𝐥𝐢𝐩𝐡𝐞𝐫𝐨𝐧 𝐜𝐨𝐥𝐥𝐞𝐜𝐭𝐢𝐨𝐧 (https://www.alipheron.com/spaces/), showcasing how the system identifies structurally diverse hits that strictly adhere to the critical pharmacophoric orientation of the Adagrasib template.