Early investigation of a novel SI306 theranostic prodrug for glioblastoma treatment.

Glioblastoma multiforme (GBM) is one of the most aggressive malignancies with a high recurrence rate and poor prognosis. Theranostic, combining therapeutic and diagnostic approaches, arises as a successful strategy to improve patient outcomes through personalized medicine. Src is a non-receptor tyrosine kinase (nRTK) whose involvement in GBM has been extensively demonstrated. Our previous research highlighted the effectiveness of the pyrazolo[3,4-d]pyrimidine SI306 and its more soluble prodrug CMP1 as Src inhibitors both in in vitro and in vivo GBM models. In this scenario, we decided to develop a theranostic prodrug of SI306, ProSI-DOTA(68 Ga) 1, which was designed to target GBM cells after hydrolysis and follow-up on the disease's progression and improve the therapy's outcome. First, the corresponding nonradioactive prodrug 2 was tested to evaluate its ADME profile and biological activity. It showed good metabolic stability, no inhibition of CYP3A4, suboptimal aqueous solubility, and slight gastrointestinal and blood-brain barrier passive permeability. Compound 2 exhibited a drastic reduction of cell vitality after 72 h on two different GBM cell lines (GL261 and U87MG). Then, 2 was subjected to complexation with the radionuclide Gallium-68 to give ProSI-DOTA(68 Ga) 1. The cellular uptake of 1 was evaluated on GBM cells, highlighting a slight but significant time-dependent uptake. The data obtained from our preliminary studies reflect the physiochemical properties of 1. The use of an alternative route of administration, such as the intranasal route, could overcome the physiochemical limitations and enhance the pharmacokinetic properties of 1, paving the way for its future development.

Identification and Biological Characterization of the Pyrazolo[3,4-d]pyrimidine Derivative SI388 Active as Src Inhibitor.

Src is a non-receptor tyrosine kinase (TK) whose involvement in cancer, including glioblastoma (GBM), has been extensively demonstrated. In this context, we started from our in-house library of pyrazolo[3,4-d]pyrimidines that are active as Src and/or Bcr-Abl TK inhibitors and performed a lead optimization study to discover a new generation derivative that is suitable for Src kinase targeting. We synthesized a library of 19 compounds, 2a-s. Among these, compound 2a (SI388) was identified as the most potent Src inhibitor. Based on the cell-free results, we investigated the effect of SI388 in 2D and 3D GBM cellular models. Interestingly, SI388 significantly inhibits Src kinase, and therefore affects cell viability, tumorigenicity and enhances cancer cell sensitivity to ionizing radiation.

Novel pyrazolo[3,4-d]pyrimidines as dual Src/Bcr-Abl kinase inhibitors: Synthesis and biological evaluation for chronic myeloid leukemia treatment.

The Bcr-Abl tyrosine kinase (TK) is the molecular hallmark of chronic myeloid leukemia (CML). Src is another TK kinase whose involvement in CML was widely demonstrated. Small molecules active as dual Src/Bcr-Abl inhibitors emerged as effective targeted therapies for CML and a few compounds are currently in clinical use. In this study, we applied a target-oriented approach to identify a family of pyrazolo[3,4-d]pyrimidines as dual Src/Bcr-Abl inhibitors as anti-leukemia agents. Considering the high homology between Src and Bcr-Abl, in-house Src inhibitors 8a-l and new analogue compounds 9a-n were screened as dual Src/Bcr-Abl inhibitors. The antiproliferative activity on K562 CML cells and the ADME profile were determined for the most promising compounds. Molecular modeling studies elucidated the binding mode of the inhibitors into the Bcr-Abl (wt) catalytic pocket. Compounds 8j and 8k showed nanomolar activities in enzymatic and cellular assays, together with favorable ADME properties, emerging as promising candidates for CML therapy. Finally, derivatives 9j and 9k, emerging as valuable inhibitors of the most aggressive Bcr-Abl mutation, T315I, constitute a good starting point in the search for compounds able to treat drug-resistant forms of CML. Overall, this study allowed us to identify more potent compounds than those previously reported by the group, marking a step forward in searching for new antileukemic agents.

Synthetic Heterocyclic Derivatives as Kinase Inhibitors Tested for the Treatment of Neuroblastoma.

In the last few years, small molecules endowed with different heterocyclic scaffolds have been developed as kinase inhibitors. Some of them are being tested at preclinical or clinical levels for the potential treatment of neuroblastoma (NB). This disease is the most common extracranial solid tumor in childhood and is responsible for 10% to 15% of pediatric cancer deaths. Despite the availability of some treatments, including the use of very toxic cytotoxic chemotherapeutic agents, high-risk (HR)-NB patients still have a poor prognosis and a survival rate below 50%. For these reasons, new pharmacological options are urgently needed. This review focuses on synthetic heterocyclic compounds published in the last five years, which showed at least some activity on this severe disease and act as kinase inhibitors. The specific mechanism of action, selectivity, and biological activity of these drug candidates are described, when established. Moreover, the most remarkable clinical trials are reported. Importantly, kinase inhibitors approved for other diseases have shown to be active and endowed with lower toxicity compared to conventional cytotoxic agents. The data collected in this article can be particularly useful for the researchers working in this area.

Si113-prodrugs selectively activated by plasmin against hepatocellular and ovarian carcinoma.

Si113, a pyrazolo[3,4-d]pyrimidine derivative, gained more attention as an anticancer agent due to its potent anticancer activity on both in vitro and in vivo hepatocellular carcinomas (HCC) and ovarian carcinoma models. But the drawback is the low water solubility which prevents its further development. In this context, we successfully overcame this limitation by synthesizing two novel prodrugs introducing the amino acid sequence D-Ala-Leu-Lys (TP). Moreover, TP sequence has a high affinity with plasmin, a protease recognized as overexpressed in many solid cancers, including HCC and ovarian carcinoma. The prodrugs were synthesized and fully characterized in terms of in vitro ADME properties, plasma stability and plasmin-induced release of the parent drug. The inhibitory activity against Sgk1 was evaluated and in vitro growth inhibition was evaluated on ovarian carcinoma and HCC cell lines in the presence and absence of human plasmin. In vivo pharmacokinetic properties and preliminary tissue distribution confirmed a better profile highlighting the importance of the prodrug approach. Finally, the prodrug antitumor efficacy was evaluated in an HCC xenografted murine model, where a significant reduction (around 90%) in tumor growth was observed. Treatment with ProSi113-TP in combination with paclitaxel in a paclitaxel-resistant ovarian carcinoma xenografted murine model, resulted in an impressive reduction of tumor volume greater than 95%. Our results revealed a promising activity of Si113 prodrugs and pave the way for their further development against resistant cancer.