Sunitinib for metastatic renal cell carcinoma

Discovery of novel diaryl urea-oxindole hybrids as BRAF kinase inhibitors targeting BRAF and KRAS mutant cancers

In the current study, a novel series of diaryl urea incorporating oxindole moiety was rationally designed as type II BRAF inhibitors targeting BRAF and KRAS mutant cancers. Molecular hybridization between the diaryl urea scaffold which binds to the inactive conformation of protein kinases on one side and the oxindole core which exhibit adenine mimic properties to be settled in the hinge region on the other side was performed. Studying the antiproliferative activity of the synthesized candidates 9a-t on NCI cancer cell lines showed that they exhibit potent and broad spectrum of antiproliferative activity on the tested cancer cell lines with compounds 9c, 9p, 9q, 9s, and 9t demonstrating potent GI50 reaching 0.01 µM. Noteworthy, compound 9s demonstrated a potent GI50 on cell lines expressing mutant KRAS and those express BRAFV600E with GI50 ranges of 1.79 and 7.94 µM and 1.68 to 2.0 µM, respectively. Further analysis on A375 and Mel501 cell lines expressing BRAFV600E revealed that compound 9s has a potent growth inhibitory activity with IC50 of 0.7 and 1.5 µM, respectively, in reference to sorafenib (IC50 = 8.7 and 0.3 µM, respectively). Additionally, nearly all the target candidates did not show any cytotoxic effect on the normal fibroblast cell line BJ-1 with compound 9s showing IC50 of 20.2 µM in reference to sorafenib (IC50 = 6.1 µM). Further cellular assays on A375 cell line, revealed the ability of compound 9s to halt the cell cycle progression at the G2 phase besides its ability to induce apoptosis. In parallel, all the synthesized candidates 9a-t were biochemically evaluated for their inhibitory activity on BRAFWT and compounds 9b, 9c, and 9n revealed a sub-micromolar IC50 of 0.11, 0.84 and 0.80 µM, respectively. Further investigation of selected compounds on BRAFV600E showed that compounds 9c, 9n, 9s, and 9t exhibit a sub-micromolar IC50 range of 0.17 to 0.89 µM. Noteworthy, the examined candidates demonstrated a higher selectively towards BRAFV600E over BRAFWT highlighting their promising optimization for treating BRAFV600E expressing cancers. Molecular docking and molecular dynamics simulations in the inactive DFG-out kinase domain of BRAFWT/V600E protein kinases confirmed the planned design strategy.

Benzimidazole-oxindole hybrids: A novel class of selective dual CDK2 and GSK-3β inhibitors of potent anticancer activity

A new series of benzimidazole-oxindole hybrids 8a-x was discovered as dual cyclin-dependent kinase (CDK2) and glycogen synthase kinase-3-beta (GSK-3β) inhibitors with potent anticancer activity. The synthesized hits displayed potent anticancer activity against national cancer institute cancer cell lines in single-dose and five-dose assays. Moreover, the derivatives 8k, 8l, 8n, 8o, and 8p demonstrated potent cytotoxic activity against PANC-1 cells with IC50 = 1.88-2.79 µM. In addition, the hybrids 8l, 8n, 8o, and 8p displayed potent antiproliferative activity on the MG-63 cell line (IC50 = 0.99-1.90 µM). Concurrently, the benzimidazole-oxindole hybrid 8v exhibited potent dual CDK2/GSK-3β inhibitory activity with IC50 values of 0.04 and 0.021 µM, respectively. In addition, 8v displayed more than 10-fold higher selectivity toward CDK2 and GSK-3 β over CDK1, CDK5, GSK-3α, vascular endothelial growth factor receptor-2, and B-rapidly accelerated fibrosarcoma. Screening of the effect of 8n and 8v on the cell cycle and apoptosis of PANC-1 and MG-63 cells displayed their ability to arrest their cell cycle at the G2-M phase and to potentiate the apoptosis of both cell lines. In silico docking of the benzimidazole-oxindole hybrid 8v into the catalytic pocket of both CDK2 and GSK-3β revealed its perfect fitting through the formation of hydrogen bonding and hydrophobic interactions with the key amino acids in the binding sites. In addition, in silico absorption, distribution, metabolism, excretion studies proved that 8a-x exhibit satisfactory drug-likeness properties for drug development.

Quinazoline-oxindole hybrids as angiokinase inhibitors and anticancer agents: Design, synthesis, biological evaluation, and molecular docking studies

Two new sets of quinazoline-oxindole 8a-l and quinazoline-dioxoisoindoline 10a-d hybrids were designed as type II angiokinase inhibitors and anticancer agents. The design strategy was adjusted to account for the quinazoline scaffold's placement in the target kinases' hinge region, where it would form hydrogen bonding and hydrophobic interactions with the important amino acids to stabilize it, and the amide group's occupation in the gate region, which would direct the oxindole scaffold toward the hydrophobic back pocket. The two sets of quinazolines 8a-l and 10a-d displayed pronounced inhibitory activity on VEGFR-2 (IC50 = 0.46-2.20 µM). The quinazoline-oxindole hybrids 8d, 8f, and 8h displayed IC50 = 0.46, 0.49, and 0.49 µM, respectively. Compound 8f demonstrated potent multikinase activity with IC50 values of 0.95 and 0.67 µM against FGFR-1 and BRAF, respectively. Additionally, compound 8f showed significant anticancer activity against National Cancer Institute's cancer cell lines, with GI50 reaching 1.21 µM. Analysis of the impact of compound 8f on the MDA-MB-231 cell line's cell cycle and apoptosis revealed that 8f stalled the cell cycle at the G2/M phase and promoted its necrosis.

Oxindole-benzothiazole hybrids as CDK2 inhibitors and anticancer agents: design, synthesis and biological evaluation

In the current study, molecular hybridization between the oxindole core and benzothiazole system through an acetohydrazide moiety was accomplished for the design of a new series of oxindole-benzothiazole hybrids 9a-r targeting CDK2 for cancer therapy. The afforded hybrids displayed promising growth inhibitory activity on NCI cancer cell lines at 10 µM. Compound 9o displayed mean GI% = 55.91%. Based on the potent activity of 9o, it was further assessed for its cytotoxic activity at five dose level and it demonstrated GI50 reaching 2.02 µM. Analysis of the cell cycle of the prostate cancer cell line DU145 after treatment with 9o confirmed its ability to arrest its cell cycle at the G1 phase. Moreover, 9o proved its ability to potentiate the apoptosis and necrosis of the same cell line. Furthermore, the oxindole-benzothiazole hybrids 9b, 9f and 9o showed IC50 = 0.70, 0.20 and 0.21 µM, respectively on CDK2. Besides, molecular docking simulation of the synthesized oxindole-benzothiazole hybrid 9o proved the expected binding mode which involves the accommodation of the oxindole moiety in the ATP binding pocket where it is involved in hydrogen bonding and hydrophobic interactions with the essential amino acids in the hinge region while the benzothiazole moiety is oriented toward the solvent region. Investigation of the physicochemical properties of the hybrids 9a-r highlights their acceptable ADME properties that can be somewhat developed for the discovery of new anticancer agents.

Benzimidazole-oxindole hybrids as multi-kinase inhibitors targeting melanoma

In the current study, a series of benzimidazole-oxindole conjugates 8a-t were designed and synthesized as type II multi-kinase inhibitors. They exhibited moderate to potent inhibitory activity against BRAFWT up to 99.61 % at 10 µM. Notably, compounds 8e, 8k, 8n and 8s demonstrated the most promising activity, with 99.44 to 99.61 % inhibition. Further evaluation revealed that 8e, 8k, 8n and 8s exhibit moderate to potent inhibitory effects on the kinases BRAFV600E, VEGFR-2, and FGFR-1. Additionally, compounds 8a-t were screened for their cytotoxicity by the NCI, and several compounds showed significant growth inhibition in diverse cancer cell lines. Compound 8e stood out with a GI50 range of 1.23 - 3.38 µM on melanoma cell lines. Encouraged by its efficacy, it was further investigated for its antitumor activity and mechanism of action, using sorafenib as a reference standard. The hybrid compound 8e exhibited potent cellular-level suppression of BRAFWT, VEGFR-2, and FGFR-1 in A375 cell line, surpassing the effects of sorafenib. In vivo studies demonstrate that 8e significantly inhibits the growth of B16F10 tumors in mice, leading to increased survival rates and histopathological tumor regression. Furthermore, 8e reduces angiogenesis markers, mRNA expression levels of VEGFR-2 and FGFR-1, and production of growth factors. It also downregulated Notch1 protein expression and decreased TGF-β1 production. Molecular docking simulations suggest that 8e binds as a promising type II kinase inhibitor in the target kinases interacting with the key regions in their kinase domain.

Sunitinib in advanced metastatic non-clear cell renal cell carcinoma: a single institution retrospective study

AIM

Sunitinib is an orally active multi-targeted tyrosine kinase inhibitor that exerts its antitumor effects primarily through the selective inhibition of VEGF. Novel targeted therapies such as sunitinib have transformed the treatment of advanced metastatic renal cell carcinomas, particularly those with clear cell histology. Here, our experience in patients with non-clear cell kidney cancer treated as part of the sunitinib Expanded Access Program is reported.

MATERIALS & METHODS

This was a retrospective assessment of 21 patients with non-clear cell renal cell carcinoma who were treated with oral sunitinib 50 mg/day in repeated 6 weekly cycles (4 weeks on and 2 weeks off). Disease assessment and physical examination were recorded at baseline and tumor assessments were performed every 3 months, according to Response Evaluation Criteria In Solid Tumors. The primary outcome measure was progression-free survival.

RESULTS

Patients received an average of 6.38 cycles of sunitinib; one patient was classified as a complete responder and two as partial responders. The overall response rate was 14.3% and clinical benefit was attained by 52.4%. The median progression-free survival was 4.1 months while median overall survival was 14.6 months. In general, sunitinib was well tolerated and only three patients experienced a grade 3 toxicity, which resolved with dosage reduction.

CONCLUSION

As expected, sunitinib exerted lower antitumor activity in patients with non-clear cell renal cell carcinoma than was achieved in the general population with metastatic kidney cancer. However, responses (one complete and two partial) were documented and clinical benefit was observed in more than half of all patients.

Hypertension as a potential biomarker of efficacy in patients with gastrointestinal stromal tumor treated with sunitinib

BACKGROUND

Reliable biomarkers of sunitinib response in gastrointestinal stromal tumor (GIST) are lacking. Hypertension (HTN), an on-target class effect of vascular endothelial growth factor signaling-pathway inhibitors, has been shown to correlate with clinical outcome in advanced renal cell carcinoma treated with sunitinib.

PATIENTS AND METHODS

This retrospective analysis examined correlations between sunitinib-associated HTN and antitumor efficacy (N = 319) and safety (N = 1565) across three advanced GIST studies. Blood pressure (BP) was measured on days 1 and 28 of each treatment cycle at a minimum. Time-to-event endpoints were estimated using Kaplan-Meier methods, and patient subgroups with and without HTN (maximum systolic BP ≥ 140 mmHg and/or diastolic BP ≥ 90 mmHg) were compared using Cox proportional hazards models. Landmark analyses evaluated associations between early HTN and efficacy endpoints. Adverse events (AEs) were compared between groups.

RESULTS

Sunitinib-associated HTN correlated with improved objective response rates, time to tumor progression, progression-free survival, and overall survival. Almost all benefits remained significant in multivariate and landmark analyses. Overall incidences of HTN-related AEs were low and similar between groups; incidences of cardiovascular AEs were somewhat higher in patients with HTN.

CONCLUSION

Sunitinib-associated HTN appeared to correlate with improved clinical outcomes in GIST, while incidences of HTN-associated AEs were generally low and manageable.

Lipid-based nanoformulation of irinotecan: dual mechanism of action allows for combination chemo/angiogenic therapy

A number of studies have outlined the antiangiogenic effects of cytotoxic agents when administered frequently at low doses. These studies suggest that the effect of the cytotoxic agent is on the vasculature within the tumor and it is assumed that there is little or negligible cytotoxicity. Liposomal drug delivery systems have the ability to provide a dual mechanism of activity where tumor accumulation can deliver high local concentrations of the drug at the site of action with concomitant slow release of the drug from carriers in the blood compartment that results in antivascular effects, similar to that achieved when dosing frequently at low levels. Although this dual mechanism of activity may be linked to other lipid nanoparticle formulations of anticancer drugs, this article summarizes the evidence supporting direct (cytotoxic) and indirect (antivascular) actions of a liposomal formulation of irinotecan.