Leukemia is a malignancy of the blood or bone marrow characterized by an uncontrolled growth of white blood cells. Like all cancer types, human leukemia is the product of many mutations that change gene expression and function, interfering with the delicate balance between differentiation, proliferation, and apoptosis [1]. Acute lymphoblastic leukemia (ALL), acute myelogenous leukemia (AML), chronic lymphocytic leukemia (CLL), and chronic myelogenous leukemia (CML) are the four primary types of leukemia based on the type of cells impacted [2]. According to Globocan's estimates, the global leukemia epidemic in 2020 claimed the lives of around 311,594 individuals of both sexes [3]. Src family kinases (SFKs) are non-receptor tyrosine kinases that play a crucial role in the proliferation and progression of leukemia cells, thus implicating c-Src as an attractive molecular target for anticancer therapy [4]. It is of great interest to develop Src inhibitors for the treatment of cancer, given the low survival rates of leukemia patients and the link between aggressive neoplastic behavior and c-Src activity [5], [6], [7]. Given that Src and the active form of Abl exhibit remarkable similarity, a number of Src inhibitors were found to exhibit strong Bcr-Abl inhibitory activity and were classified as second-generation antileukemia medicines. Dasatinib and bosutinib are therefore described as dual inhibitors of the kinases Src and Abl [8], [9] (Fig. 1). Furthermore, a number of Src inhibitors have been created; some, such as gefitinib [10], ponatinib [11], and saracatinib [12], have already been approved (Fig. 1). Moreover, it has been reported that sorafenib suppresses STAT3 phosphorylation by inhibiting Src/Abl kinase enzymes, which in turn causes apoptosis and inhibits proliferation in human AML cell line (HL60) cells [13] (Fig. 1). Within the same framework, numerous Src/Abl small molecule inhibitors have been the subject of recent clinical trials. These inhibitors include heterocyclic ATP analogues such as pyrazolo[2,3-d]pyrimidines, pyrrolo[2,3-d]pyrimidines, pyrido[2,3-d]pyrimidines, and quinolones [14], [15]. Recently, some arylbiguanide derivatives were reported to significantly suppress hypoxia-induced factor-1 (HIF-1) which is described as an important factor that enable leukemia cell lines to survive under hypoxia and low nutrition stresses in the tumor microenvironment. Among these, compound I showed inhibitory effect against HIF-1 with an IC50 = 2.0 μM [16]. Furthermore, novel aryl bearing guanidinoethyl moiety II was synthesized as potential DNA-specific carrier ligands for platinum which revealed remarkable cytotoxicity against HL-60 cells with IC50 = 8.4 μM.[17], [18] (Fig. 2). Previous research has indicated that the “in situ normoxia” circumstances should serve as the basis for a validated biological assessment of antileukemia candidates [19].

Since pyrimidine derivatives and their fused rings are bioisostere skeletons, so the pyrimidine scaffold may be a key target for Src/Abl inhibitors. In this work, we aimed to synthesize a new class of disubstituted guanidine generated from pyrimidine rings as Src/Abl dual inhibitors, based on results from the literature and our previous work involving molecular modeling and synthesis of anti-neoplastic compounds [20], [21], [22], [23], [24], [25], [26]. As guanidines can establish hydrogen bonds with the amino-acid residues of the DFG-out pocket of kinases, they were developed to be a bioisostere for the urea moiety, which may contribute to a potential binding affinity to the Src or Abl enzymes. The pyrimidine ring, located in the ATP binding site is an isostere for the adenine scaffold. After assessing all the synthesized compounds against the NSC 60 cancer cell lines panel, the most effective inhibitor was selected for further evaluation under both normoxic and hypoxic leukemia cell lines. Additionally, the inhibitory function of Src/Abl was investigated in the strong antiproliferative drugs. In silico docking study was performed to demonstrate the binding affinity of the synthesized compounds for the Src enzyme binding site.