Discovery of a novel 4-Pyridyl SLC-0111 Analog Targeting Tumor-Associated Carbonic Anhydrase Isoform IX Through Tail-Based Design Approach with Potent Anticancer Activity

Hamada Hashem ¹ Shadwa Abdelfattah ² Hesham Hassan ³ Ahmed Al-Emam ³ Mohammed Alqarni ⁴ Ghallab Alotaibi ⁵ Ibrahim Taha Radwan ⁶ Kirandeep Kaur ⁷ Devendra Pratap Rao ^8* Stefan Bräse ^9* Abdullah Alkhammash ⁵

• ¹ Pharmaceutical Chemistry Department, Faculty of Pharmacy, Sohag University, Sohag, Egypt
• ² Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Merit University (MUE), Sohag, Egypt
• ³ Department of Pathology, College of Medicine, King Khalid University, Asir, Saudi Arabia
• ⁴ Department of Pharmaceutical chemistry, College of Pharmacy, Taif University, P.O. Box 11099, Taif, Saudi Arabia
• ⁵ Department of Pharmacology, College of Pharmacy, Al-Dawadmi Campus, Shaqra University, Shaqra, Saudi Arabia
• ⁶ Supplementary General Sciences Department, Faculty of Oral and Dental Medicine, Future University in Egypt, Cairo, Egypt
• ⁷ Department of Chemistry, Maharaja Ranjit Singh Punjab Technical University, Bathinda 151001, Punjab, India
• ⁸ Dayanand Anglo-Vedic (PG) College, Kanpur, India
• ⁹ Karlsruhe Institute of Technology (KIT), Karlsruhe, Baden-Württemberg, Germany

This study reports the design, synthesis, evaluation, and in-silico analysis of a novel 4-pyridyl analog of SLC-0111 (designated Pyr), targeting tumor-associated carbonic anhydrase IX (CA IX). Pyr was designed with a tail-based approach to enhance interactions with the hydrophobic region of the CA IX active site. Pyr demonstrated selective cytotoxicity against HT-29, MCF7, and PC3 cancer cell lines, with IC₅₀ values of 27.74 µg/mL, 11.20 µg/mL, and 8.36 µg/mL, respectively, while showing reduced toxicity toward normal CCD-986sk cells (IC₅₀ = 50.32 µg/mL). Pyr exhibited potent inhibition of CA IX (IC₅₀ = 0.399 µg/mL), with moderate activity against other CA isoforms (CA I, II, and XII). Mechanistically, Pyr induced G0/G1 cell cycle arrest and promoted apoptosis in PC3 cells, reflected by increased caspase-3 and caspase-9 activities and changes in Bax/Bcl-2 and p53 expression. In-silico molecular docking studies confirmed Pyr's strong binding affinity to the CA IX active site, with several stabilizing interactions. ADMET predictions further affirmed Pyr's drug-like properties, suggesting good oral bioavailability and minimal off-target toxicity. Collectively, these results establish Pyr as a promising candidate for targeted cancer therapy, warranting further preclinical evaluation.