A phase II study of efficacy and safety of the MEK inhibitor tunlametinib in patients with advanced NRAS-mutant melanoma.

BACKGROUND: NRAS-mutant melanoma is an aggressive subtype with poor prognosis; however, there is no approved targeted therapy to date worldwide. METHODS: We conducted a multicenter, single-arm, phase II, pivotal registrational study that evaluated the efficacy and safety of the MEK inhibitor tunlametinib in patients with unresectable, stage III/IV, NRAS-mutant melanoma (NCT05217303). The primary endpoint was objective response rate (ORR) assessed by independent radiological review committee (IRRC) per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1. The secondary endpoints included progression-free survival (PFS), disease control rate (DCR), duration of response(DOR), overall survival (OS) and safety. FINDINGS: Between November 2, 2020 and February 11, 2022, a total of 100 patients were enrolled. All (n = 100) patients received at least one dose of tunlametinib (safety analysis set [SAS]) and 95 had central laboratory-confirmed NRAS mutations (full analysis set [FAS]). In the FAS, NRAS mutations were observed at Q61 (78.9%), G12 (15.8%) and G13 (5.3%). The IRRC-assessed ORR was 35.8%, with a median DOR of 6.1 months. The median PFS was 4.2 months, DCR was 72.6% and median OS was 13.7 months. Subgroup analysis showed that in patients who had previously received immunotherapy, the ORR was 40.6%. No treatment-related deaths occurred. INTERPRETATION: Tunlametinib showed promising antitumor activity with a manageable safety profile in patients with advanced NRAS-mutant melanoma, including those who had prior exposure to immunotherapy. The findings warrant further validation in a randomized clinical trial.

Evaluation of the radiosensitizing effect of MEK inhibitor KZ-001 on non-small cell lung cancer cells in vitro.

Background: Non-small cell lung cancer (NSCLC) has a poor prognosis and usually presents resistance against radiotherapy. MEK inhibitors have been proven to possess a radiosensitization effect. The compound KZ-001 as a particular MEK inhibitor is superior to the listed MEK inhibitor AZD6244. Objective: To investigate whether KZ-001 could enhance the radiosensitivity of NSCLC cell lines in vitro. Methods: MTT and colony formation assay were used to evaluate the radiosensitivity effect of KZ-001. Immunofluorescence, cell cycle, apoptosis staining, and western blot experiments were used to explore the radiosensitivity mechanism. Results: KZ-001 significantly decreased A549 cell viability at 6 Gy and 8 Gy radiation doses and caused the radiosensitivity at 1 Gy, 4 Gy, and 6 Gy in colony formation experiments. The A549 apoptosis ratio induced by irradiation (IR) combined with KZ-001 increased significantly in comparison with that by IR monotherapy (10.57% vs. 6.23%, P = 0.0055). The anti-apoptosis marker Bcl-XL was found downregulated in KZ-001 and IR-treated A549/H460 cells, but apoptosis marker Bax was downregulated in H460. Extracellular regulated protein kinases (ERK1/2) phosphorylation of H460 cells could be blocked both by IR alone and IR combined with KZ-001. IR combined with KZ-001 is able to inhibit ERK activation of A549 cells apparently. KZ-001 increased the proportion of G2 phase in irradiated cells from 21.24% to 32.22%. KZ-001 could also significantly increase the double-strand break damage cell ratio to more than 30% compared to the irradiation alone group. Conclusions: MEK1/2 inhibitor KZ-001 is a potential radiosensitizer for clinical applications.

Preclinical characterization of tunlametinib, a novel, potent, and selective MEK inhibitor.

Background: Aberrant activation of RAS-RAF-MEK-ERK signaling pathway has been implicated in more than one-third of all malignancies. MEK inhibitors are promising therapeutic approaches to target this signaling pathway. Though four MEK inhibitors have been approved by FDA, these compounds possess either limited efficacy or unfavorable PK profiles with toxicity issues, hindering their broadly application in clinic. Our efforts were focused on the design and development of a novel MEK inhibitor, which subsequently led to the discovery of tunlametinib. Methods: This study verified the superiority of tunlametinib over the current MEK inhibitors in preclinical studies. The protein kinase selectivity activity of tunlametinib was evaluated against 77 kinases. Anti-proliferation activity was analyzed using the 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) or (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) (MTS) assay. ERK and phospho-ERK levels were evaluated by Western blot analysis. Flow cytometry analysis was employed to investigate cell cycle and arrest. Cell-derived xenograft (CDX) and Patient-derived xenograft (PDX) models were used to evaluate the tumor growth inhibition. The efficacy of tunlametinib as monotherapy treatment was evaluated in KRAS/BRAF mutant or wild type xenograft model. Furthermore, the combination studies of tunlametinib with BRAF/KRASG12C/SHP2 inhibitors or chemotherapeutic agent were conducted by using the cell proliferation assay in vitro and xenograft models in vivo. Results: In vitro, tunlametinib demonstrated high selectivity with approximately 19-fold greater potency against MEK kinase than MEK162, and nearly 10-100-fold greater potency against RAS/RAF mutant cell lines than AZD6244. In vivo, tunlametinib resulted in dramatic tumor suppression and profound inhibition of ERK phosphorylation in tumor tissue. Mechanistic study revealed that tunlametinib induced cell cycle arrest at G0/G1 phase and apoptosis of cells in a dose-proportional manner. In addition, tunlametinib demonstrated a favorable pharmacokinetic profile with dose-proportionality and good oral bioavailability, with minimal drug exposure accumulation. Furthermore, tunlametinib combined with BRAF/KRASG12C/SHP2 inhibitors or docetaxel showed synergistically enhanced response and marked tumor inhibition. Conclusion: Tunlametinib exhibited a promising approach for treating RAS/RAF mutant cancers alone or as combination therapies, supporting the evaluation in clinical trials. Currently, the first-in-human phase 1 study and pivotal clinical trial of tunlametinib as monotherapy have been completed and pivotal trials as combination therapy are ongoing.

Compound 5 alleviated acute kidney injury without affecting the antitumor effect after cisplatin treatment.

Despite being a powerful weapon against cancer cells, cisplatin's therapeutic potential is hampered by numerous adverse reactions, including acute kidney injury (AKI). Compound 5 has 3-SH fragments at the end of the vertical short alkyl side chain, which is an ROS scavenger synthesized. In this study, we evaluated the protective effect of compound 5 on the kidney after cisplatin administration and its mechanism. The results founded that compound 5 can alleviate serum urea nitrogen and serum creatinine induced by cisplatin administration in vivo. In addition, histopathological analysis of the kidneys showed that compound 5 significantly reduced cisplatin-induced (Cis-induced) renal toxicity compared with the cisplatin group. A mechanism study showed that compound 5 significantly reduces NOX4 levels, improves the activity of antioxidant enzymes (SOD and GSH-Px), reduces Malondialdehyde (MDA) levels, increases the total antioxidant level, reduces oxidative stress, and thus reduces kidney tissue damage. At the same time, compound 5 activated the Nrf2 signaling pathway. In addition, it can increase the expression of Bax, reduce the expression of Bcl-2 and caspase-3, a marker of apoptosis, which is beneficial to the survival of kidney cells. Additionally, compound 5 did not interfere with the antitumor effects of cisplatin in in vivo xenotransplantation models.

KZ02 enhances the radiosensitivity of BRAF-mutated CRC in vitro and in vivo.

Colorectal cancer (CRC) is a common malignant tumor with a high incidence and mortality worldwide. Preoperative chemoradiotherapy is a common treatment for patients with metastatic colorectal cancer (mCRC) as it reduces colostomy and local recurrence. The RAS (rat sarcoma)-RAF (extracellular signal-regulated kinase)-MEK (mitogen-activated protein kinase)-ERK (extracellular signal-regulated kinase) pathway regulates important cellular processes in the CRC. Abnormal ERK activation stimulates cell growth and provides a survival advantage. Our group has previously reported that the compound KZ02 has a stronger ability to inhibit tumor growth than AZD6244 (a MEK inhibitor). In this study, we evaluated the antitumor activity of KZ02 in combination with ionizing radiation (IR) and investigated its mechanism of action in BRAF-mutated colorectal cancer. Our results showed that this combination kills tumor cells better than either radiation or drugs alone, both in vivo and in vitro. Furthermore, studies have shown that KZ02 inhibits ERK overactivation. The combination resulted in a G1 phase arrest, a reduction in the radioresistant S phase, and aggravating DNA damage. It can also inhibit Pim-1 (Moloney murine leukemia virus-1), p-BAD (Bcl-2 associated agonist of cell death), Bcl-2 (B-cell lymphoma 2) and Bcl-XL (B-cell lymphoma-extra large) levels and promote apoptosis when combined with radiation. Our results suggest that KZ02 significantly increases the radiosensitivity of BRAF-mutated CRC cells by perturbing the cell cycle, increasing DNA damage, and promoting tumor apoptosis.

Protective mechanism of a novel aminothiol compound on radiation-induced intestinal injury.

PURPOSE: With the development of nuclear technology and radiotherapy, the risk of radiation injury has been increasing. Therefore, it is important to find an effective radiation-protective agent. In this study, we designed and synthesized a novel compound called compound 8, of which the radioprotective effect and mechanism were studied. MATERIALS AND METHODS: Before being exposed to ionizing radiation, mice were pretreated with compound 8. The 30-day mortality assay, hematoxylin-eosin staining, and immunohistochemistry staining assay were performed to evaluate the anti-radiation effect of the compound 8. TUNEL and immunofluorescence assays were conducted to study the anti-radiation mechanism of compound 8. RESULTS: Compared to the IR + vehicle group, the 30-day survival rate of mice treated with 25 mg/kg of compound 8 was significantly improved after 8 Gy total body irradiation. In the morphological study of the small intestine, we found that compound 8 could maintain crypt-villus structures in the irradiated mice. Further immunohistochemical staining displayed that compound 8 could improve the survival of Lgr5+ cells, ki67+ cells, and lysozyme+ cells. The results of TUNEL and immunofluorescence assays showed that compound 8 could decrease the expression of apoptosis-related caspase-8/-9, γ-H2AX, Bax, and p53. CONCLUSIONS: These results indicate that compound 8 exerts its effects by maintaining structure and function of small intestine. It also reduces DNA damage, promotes crypt proliferation and differentiation. Moreover, it may enhance the anti-apoptotic ability of small intestinal tissue by inhibiting the activation of p53 and blocking the caspase cascade reaction. Compound 8 can protect the intestinal tract from post-radiation damage, it is thus a new and effective protective agent of radiation.

Phase I pharmacokinetic study of an oral, small-molecule MEK inhibitor tunlametinib in patients with advanced NRAS mutant melanoma.

Background: Malignant melanoma is an aggressive disease. Tunlametinib (HL-085) is a potent, selective, and orally bioavailable MEK1/2 inhibitor. The objective of this study was to determine the pharmacokinetics (PK) of tunlametinib and its main metabolite M8 in patients with NRAS-mutant melanoma following a single dose and multiple doses in a phase I safety and PK study. Methods: A multiple-center phase I study was performed in patients with melanoma including dose-escalation phase and dose-expansion phase. PK following a single oral dose and multiple doses of 0.5-18 mg twice daily was assessed. Results: A total of 30 participants were included in the dose escalation phase and then 11 patients were included in the dose-expansion phase (12 mg twice daily). Tunlametinib plasma concentration rapidly increased after dosing, with a Tmax of 0.5-1 h. Mean elimination half-life (t1/2) was dose-independent and had a range from 21.84 to 34.41 h. Mean apparent clearance (CL/F) and distribution volume (V/F) were 28.44-51.93 L/h and 1199.36-2009.26 L, respectively. The average accumulation ratios of AUC and Cmax after the multiple administration of tunlametinib were 1.64-2.73 and 0.82-2.49, respectively. Tunlametinib was rapidly transformed into the main metabolite M8 and M8 reached the peak concentration about 1 h after administration. Mean t1/2 of M8 was 6.1-33.54 h. The body exposure of M8 in plasma was 36%-67% of that of tunlametinib. There were general dose-proportional increases in maximum concentration (Cmax) and area under the curve (AUC) of tunlametinib and M8 both in the single dose phase and in the multiple doses phase. Conclusion: Tunlametinib was absorbed rapidly and eliminated at a medium speed after drug withdrawal. Pharmacokinetic body exposure increased in general dose-proportional manner from 0.5 mg up to 18 mg. Slight accumulation was found after multiple oral doses. The pharmacokinetics of tunlametinib and its metabolite suggest that twice daily dosing is appropriate for tunlametinib.

Radioprotective effects and mechanism of HL-003 on radiation-induced salivary gland damage in mice.

Ionizing radiation (IR) can cause damage to the structure and function of salivary glands. Our research group independently synthesized the ROS scavenger, HL-003. The aim of this study was to explore the protective effects and underlying mechanisms of HL-003 on radiation-induced salivary gland injury. Salivary flow rate measurement, H&E staining, immunohistochemistry, FRAP, TUNEL, and western blotting were used to evaluate the radioprotective effect on salivary glands. The results showed that HL-003 protected the salivary secretion function by protecting the AQP-5 protein, on the salivary epithelial cell membrane, from IR damage. HL-003 reduced oxidative stress in the salivary gland by regulating the expression of ROS-related proteins NOX4, SOD2, and 8-OHdG. Furthermore, HL-003 downregulated the expression of p-p53, Bax, caspase 3, and caspase 9, and upregulated the expression of Bcl-2, suggesting that it could inhibit the activation of p53 to reduce cell apoptosis. In conclusion, HL-003 is an effective radioprotector that prevents damage of the radiation-induced salivary gland.

Design, Synthesis, and Biological Evaluation of a Novel Aminothiol Compound as Potential Radioprotector.

The risk of radiation damage has increased with the rapid development of nuclear technology and radiotherapy. Hence, research on radioprotective agents is of utmost importance. In the present study, a novel aminothiol compound 12, containing a linear alkylamino backbone and three terminal thiols, was synthesized. Owing to the appropriate capped groups in the chains, it has an improved permeability and oral bioavailability compared to other radioprotective agents. Oral administration of compound 12 improved the survival of mice that received lethal doses of γ-irradiation. Experimental results demonstrated that compound 12 not only mitigated total body irradiation-induced hematopoietic injury by increasing the frequencies of hematopoietic stem and progenitor cells but also prevented abdominal irradiation-induced intestinal injury by increasing the survival of Lgr5+ intestinal cells, lysozyme+ Paneth cells, and Ki67+ cells. In addition, compound 12 decreased oxidative stress by upregulating the expression of Nrf2 and NQO1 and downregulating the expression of NOX1. Further, compound 12 inhibited γ-irradiation-induced DNA damage and alleviated G2/M phase arrest. Moreover, compound 12 decreased the levels of p53 and Bax and increased the level of Bcl-2, demonstrating that it may suppress radiation-induced apoptosis via the p53 pathway. These results indicate that compound 12 has the possibility of preventing radiation injury and can be a potential radioprotector for clinical applications.

Synthesis and radioprotective effects of novel hybrid compounds containing edaravone analogue and 3-n-butylphthalide ring-opening derivatives.

As the potential risk of radiation exposure is increasing, radioprotectors studies are gaining importance. In this study, novel hybrid compounds containing edaravone analogue and 3-n-butylphthalide ring-opening derivatives were synthesized, and their radioprotective effects were evaluated. Among these, compound 10a displayed the highest radioprotective activity in IEC-6 and HFL-1 cells. Its oral administration increased the survival rates of irradiated mice and alleviated total body irradiation (TBI)-induced hematopoietic damage by mitigating myelosuppression and improving hematopoietic stem/progenitor cell frequencies. Furthermore, 10a treatment prevented abdominal irradiation (ABI)-induced structural damage to the small intestine. Experiment results demonstrated that 10a increased the number of Lgr5+ intestinal stem cells, lysozyme+ Paneth cells and Ki67+ transient amplifying cells, and reduced apoptosis of the intestinal epithelium cells in irradiated mice. Moreover, in vitro and in vivo studies demonstrated that the radioprotective activity of 10a is associated to the reduction of oxidative stress and the inhibition of DNA damage. Furthermore, compound 10a downregulated the expressions of p53, Bax, caspase-9 and caspase-3, and upregulated the expression of Bcl-2, suggesting that it could prevent irradiation-induced intestinal damage through the p53-dependent apoptotic pathway. Collectively, these findings demonstrate that 10a is beneficial for the prevention of radiation damage and has the potential to be a radioprotector.

Design, synthesis, and neuroprotective effects of novel hybrid compounds containing edaravone analogue and 3-n-butylphthalide ring-opened derivatives.

To develop anti-ischemic stroke drugs with higher blood-brain barrier (BBB) penetrating capability and neuroprotective activity, a series of hybrid compounds containing edaravone analogue and 3-n-butylphthalide (NBP) ring-opened derivatives were synthesized and biologically evaluated. Among them, compound 10a displayed the highest protective activity in SH-SY5Y cells against oxygen and glucose deprivation (OGD) and H2O2 insults. Experiment results indicated that 10a could inhibit platelet aggregation via the synergistic action of the edaravone analogue and NBP, and its oral administration protected the rats against ischemia/reperfusion-induced brain injury. Moreover, 10a effectively inhibited apoptosis and reduced oxidative stress in OGD-exposed cells. Further analysis suggested that 10a might alleviate oxidative damage in SH-SY5Y cells via the modulation of the Nrf2 pathway. Collectively, these findings demonstrate that 10a can emerge as a potential candidate drug for the treatment of ischemic stroke.

Oral Codelivery of WR-1065 Using Curcumin-Linked ROS-Sensitive Nanoparticles for Synergistic Radioprotection.

Protecting the body from radiation damage is a huge medical challenge. Amifostine and curcumin are both effective radioprotectants, but their use has been greatly restricted due to various reasons including low bioavailability. Nanoscale drug delivery systems of poly(ethylene glycol)-poly(ε-caprolactone) copolymers can improve the bioavailability of drugs due to excellent biocompatibility, biodegradability, and long circulation characteristics. In this study, a new reactive oxygen species-sensitive nanocarrier fabricated by linking curcumin and thioketal to poly(ethylene glycol)-poly(ε-caprolactone) polymer was used for delivery of WR-1065 (the active ingredient of amifostine). The content of curcumin in this polymer was about 7.6%, and the drug loading of WR-1065 was 44%. The WR-1065-loaded nanoparticles (NPs) had an average size of 128.6 nm and uniform spherical morphology. These WR-1065-loaded NPs reduced the metabolism of curcumin and WR-1065 in the gastrointestinal tract and could be well absorbed by cells and distributed to multiple organs. Compared with a single drug, oral administration of WR-1065-loaded NPs demonstrated obvious radioprotective effects on the hematopoietic system and prevented intestinal injury. The 30-day survival rate after half-lethal dose (7.2 Gy) of total body irradiation was 100%. In general, WR-1065-loaded NPs improved the oral bioavailability of WR-1065 and curcumin. This multifunctional nanocarrier provides a possibility for combination therapy in treating ionizing radiation damage.

Neuroprotective Effect of a New Free Radical Scavenger HL-008 in an Ischemia-Reperfusion Injury Rat Model.

Oxidative stress plays a critical role in cerebral ischemia-reperfusion injury. We have previously developed a powerful antioxidant, HL-008. This study aimed to investigate the neuroprotective function of HL-008. HL-008 efficacy in vitro and in vivo was evaluated using a PC-12 cell oxidative stress model induced by hydrogen peroxide and a rat model of middle cerebral artery occlusion, respectively. The MTT assay was used to analyze cell viability. 2,3,5-Triphenyltetrazolium chloride and Hematoxylin and Eosin staining, immunofluorescence, western blot, and proteomics were used to evaluate the infarction volume, brain tissue morphology, apoptosis, inflammation, and related pathways. Indicators related to oxidative levels were also detected. HL-008 significantly reduced the cerebral infarction volume induced by ischemia-reperfusion, improved the neurological score, alleviated oxidative stress and inflammation in the brain tissue, reduced glial cell activation, inhibited brain tissue apoptosis by influencing multiple signaling pathways, and had a neuroprotective effect. If HL-008 is successfully developed, it could significantly improve stroke patients' quality of life.

Preclinical Evaluation of Safety, Pharmacokinetics, Efficacy, and Mechanism of Radioprotective Agent HL-003.

Amifostine is a radioprotector with high efficacy but poor safety, short half-life, no oral formulation, and poor compliance, which limits its application. With the increasing risk of exposure to radiation, the development of new radioprotective agents is critical. We previously synthesized a new amifostine derivative, the small molecule compound HL-003. In this study, we focused on evaluating the radioprotective properties of HL-003. Using the in vitro 2,2-diphenyl-1-picrylhydrazyl assay, we initially confirmed HL-003 as a strong antioxidant and demonstrated that its free radical scavenging activity was stronger than that of amifostine. Then, we performed an acute toxicity test, a 28-day toxicity test, a 30-day survival rate test, and a pharmacokinetic study, all of which provided aggregate evidence that HL-003 functioned as a small molecule radioprotector with high efficacy, a favorable safety profile, a long half-life, and oral administration. The intestinal radioprotective mechanism of HL-003 was explored in male C57 mice after abdominal irradiation by analyzing intestinal tissue samples with hematoxylin-eosin staining, immunohistochemistry, TUNEL staining, and immunofluorescence detection. The results showed that HL-003 protected intestinal DNA from radiation damage and suppressed the expression of phosphorylated histone H2AX, phosphorylated p53, and the apoptosis-related proteins caspase-8 and caspase-9, which contributed to maintaining the normal morphology of the small intestine and provided insights into the mechanism of radioprotection. Thus, HL-003 is a small molecule radioprotector with a potential application in radiation medicine.

Polycysteine as a new type of radio-protector ameliorated tissue injury through inhibiting ferroptosis in mice.

Amifostine has been the only small molecule radio-protector approved by FDA for decades; however, the serious adverse effects limit its clinical use. To address the toxicity issues and maintain the good potency, a series of modified small polycysteine peptides had been prepared. Among them, compound 5 exhibited the highest radio-protective efficacy, the same as amifostine, but much better safety profile. To confirm the correlation between the radiation-protective efficacy and the DNA binding capability, each of the enantiomers of the polycysteine peptides had been prepared. As a result, the L-configuration compounds had obviously higher efficacy than the corresponding D-configuration enantiomers; among them, compound 5 showed the highest DNA binding capability and radiation-protective efficacy. To our knowledge, this is the first study that has proved their correlations using direct comparison. Further exploration of the mechanism revealed that the ionizing radiation (IR) triggered ferroptosis inhibition by compound 5 could be one of the pathways for the protection effect, which was different from amifostine. In summary, the preliminary result showed that compound 5, a polycysteine as a new type of radio-protector, had been developed with good efficacy and safety profile. Further study of the compound for potential use is ongoing.

Design and evaluation of pH-responsive hydrogel for oral delivery of amifostine and study on its radioprotective effects.

The purpose of this study was to develop a novel pH-sensitive hydrogel which was used to regulate the acute radiation syndrome (ARS). The hydrogel was fabricated by grafting polycaprolactone onto methacrylic acid copolymer (MAC-g-PCL). Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H NMR) confirmed the obtaining of MAC-g-PCL hydrogel. The hydrogel was pH-sensitive, at pH 1.2, it was compact hydrogel, but at pH7.4, it was dissolved solution. Its inner 3D morphology was observed by scanning electron microscope (SEM). Cell experiments indicated that the MAC-g-PCL hyrogel was out of cytotoxicity. The release profile of amifostine showed that small amount drug release in simulated gastric fluid (pH 1.2) and burst release in simulated intestinal fluid (pH 7.4). Thus, the pH-sensitive hydrogels could protect amifostine from enzymatic degradation in acidic stomach and deliver effectively in the intestine. The radioprotective efficacy was determined by peripheral complete blood parameters and 30-day survival study in mice acutely exposed to 4 Gy γ-ray total body irradiation. Results suggested that oral administration MAC-g-PCL/Ami before total body irradiation protected the mice from hematopoietic ARS and enhanced their survival. Furthermore, in vivo bio-distribution studies indicated that the drug could be sustained delivered at intestinal tract and entered the bloodstream. These results demonstrated that oral administration of amifostine hydrogel provided effective radioprotection to reduce the ARS injury.

A New Compound with Increased Antitumor Activity by Cotargeting MEK and Pim-1.

Feedback circuits are one of the major causes underlying tumor resistance. Thus, compounds that target one oncogenic pathway with simultaneously blocking its compensatory pathway will be of great value for cancer treatment. Here, we develop a new MEK inhibitor designated as KZ-02 that exhibits unexpectedly higher cytotoxicity than its starting compound AZD6244, a well-known MEK inhibitor, in colorectal cancer (CRC). Subsequent kinase selectivity study identified Pim-1 as an additional cellular target for KZ-02. Further studies showed that AZD6244 and Pim-1 1 (a Pim-1 inhibitor) have a synergistic effect on CRC suppression. Mechanistic study revealed that MEK inhibition by AZD6244 leads to increased Pim-1 expression, which could be a general mechanism behind the compromised cell-killing activity of MEK inhibitors. KZ-02, despite increasing Pim-1 mRNA expression, simultaneously promotes Pim-1 proteasomal degradation. Therefore, we uncover a new MEK inhibitor KZ-02 with significantly enhanced antitumor activity by co-targeting MEK and Pim-1.

Renoprotective Effects of a New Free Radical Scavenger, XH-003, against Cisplatin-Induced Nephrotoxicity.

Acute renal injury has an incidence of 25%-30% in patients with tumors who are treated with cisplatin and in patients for whom no specific drugs are available for treatment. Amifostine is the only FDA-approved chemoprotective drug; however, its clinical application is limited because of side effects. The small-molecule antioxidant XH-003, an acute radiation syndrome- (ARS-) protective drug independently developed in our laboratory, with 100% intellectual property rights, overcomes the side effects of amifostine but retains its high efficacy. In this study, XH-003 showed a chemoprotective effect similar to that of amifostine. A mechanistic study showed that XH-003 could significantly reduce cisplatin-induced increases in serum creatinine and urea nitrogen, increase the activity of antioxidant enzymes (SOD, CAT, and GSH-Px), reduce oxidative stress and tissue inflammation, and alleviate renal tissue damage by blocking the activity of the mitochondrial apoptosis pathway. Most importantly, XH-003 could reduce the accumulation of cisplatin in renal tissue by regulating the expression of proteins involved in cisplatin uptake and excretion, such as organic cation transporter 2 and MRP2. Moreover, in an in vivo xenotransplantation model, XH-003 did not interfere with the antitumor effect of cisplatin. These data provide strong evidence that the ARS-protective agent has a great potential for protecting against chemotherapy-induced toxicity. Thus, XH-003 can be considered in antitumor therapy.

Protective effects of new aryl sulfone derivatives against radiation-induced hematopoietic injury.

The hematopoietic system is sensitive to radiation. In this research, new aryl sulfone derivatives (XH-201 and XH-202) containing a nitrogen heterocycle were designed and synthesized and their radio-protective efficacies with regard to the hematopoietic system were evaluated. XH-201 administration significantly increased the survival rate of mice after 8.0 Gy total body irradiation (TBI). The results showed that XH-201 treatment not only increased the white blood cells, platelets counts and the percentage of hematopoietic progenitor cells and hematopoietic stem cells in mice exposed to 4.0 Gy TBI but also decreased DNA damage, as determined by flow cytometric analysis of histone H2AX phosphorylation. In addition, our data demonstrated that XH-201 decreased the mitochondrial reactive oxygen species (ROS) levels in hematopoietic cells. Overall, these data suggest that XH-201 is beneficial for the protection of the hemoatopoietic system against radiation-induced injuries.

Development of ERK1/2 inhibitors as a therapeutic strategy for tumour with MAPK upstream target mutations.

Extracellular signal-regulated kinases 1 and 2 (ERK1/2) phosphorylate a variety of substrates that play key roles in promoting cell survival and proliferation. Many inhibitors, acting on upstream of the ERK pathway, exhibit excellent antitumor activity. However, drug-resistant tumour cells invariably emerge after their use due to the reactivation of ERK1/2 signalling. ERK1/2 inhibitors have shown clinical efficacy as a therapeutic strategy for the treatment of tumours with mitogen-activated protein kinase (MAPK) upstream target mutations. These inhibitors may be effective against cancers with altered MAPK upstream pathway and may be used as a possible strategy to overcome acquired resistance to MAPK inhibitors. In this review, we describe the mechanism and types of ERK1/2 inhibitors, summarise the current development status of small-molecule ERK1/2 inhibitors, including the preclinical data and clinical study progress, and discuss the future research directions for the application of ERK1/2 inhibitors.