Combretastatin A-4 (CA-4, 1) is an antimicrotubule agent used as a prototype for the design of several synthetic analogues with anti-tubulin activity, such as LASSBio-1586 (2). A series of branched and unbranched homologs of the lead-compound 2, and vinyl, ethinyl and benzyl analogues, were designed and synthesized. A comparison between the cytotoxic effect of these homologs and 2 on different human tumor cell lines was performed from a cell viability study using MTT with 48 h and 72 h incubations. In general, the compounds were less potent than CA-4, showing CC50 values ranging from 0.030 μM to 7.53 μM (MTT at 72 h) and 0.096 μM to 8.768 μM (MTT at 48 h). The antimitotic effect of the target compounds was demonstrated by cell cycle analysis through flow cytometry, and the cellular mechanism of cytotoxicity was determined by immunofluorescence. While the benzyl homolog 10 (LASSBio-2070) was shown to be a microtubule stabilizer, the lead-compound 2 (LASSBio-1586) and the methylated homolog 3 (LASSBio-1735) had microtubule destabilizing behavior. Molecular docking studies were performed on tubulin protein to investigate their binding mode on colchicine and taxane domain. Surprisingly, the benzyl homolog 10 was able to modulate EGFR phosphorylate activity in a phenotypic model. These data suggest LASSBio-2070 (10) as a putative dual inhibitor of tubulin and EGFR. Its binding mode with EGFR was determined by molecular docking and may be useful in lead-optimization initiatives.

Targeted antitumour therapy has revolutionized the treatment of several types of tumours. Among the validated targets, phosphatidylinositol-3 kinase (PI3K) deserves to be highlighted. Several PI3K inhibitors have been developed for the treatment of cancer, including gedatolisib (4). This inhibitor was elected as a prototype and molecular modifications were planned to design a new series of simplified gedatolisib analogues (5a-f). The analogues were synthesised, and the comparative cytotoxic activity profile was studied in phenotypic models employing solid and nonadherent tumour cell lines. Compound 5f (LASSBio-2252) stood out as the most promising of the series, showing good aqueous solubility (42.38 μM (pH = 7.4); 39.33 μM (pH = 5.8)), good partition coefficient (cLogP = 2.96), cytotoxic activity on human leukemia cell lines (CCRF-CEM, K562 and MOLT-4) and an excellent metabolic stability profile in rat liver microsomes (t1/2 = 462 min; Clapp = 0.058 mL/min/g). The ability of 5f to exert its cytotoxic effect through modulation of the PI3K pathway was demonstrated by flow cytometry analysis in a comparative manner to gedatolisib.