Therapeutic Drug Monitoring of Sunitinib in Gastrointestinal Stromal Tumors and Metastatic Renal Cell Carcinoma in Adults-A Review

The CYP3A inducer dexamethasone affects the pharmacokinetics of sunitinib by accelerating its metabolism in rats

Sunitinib, a novel anti-tumor small molecule targeting VEGFR, is prescribed for advanced RCC and GISTs. Sunitinib is primarily metabolized by the CYP3A enzyme. It is well-known that dexamethasone serves as a potent inducer of this enzyme system. Nonetheless, the effect of dexamethasone on sunitinib metabolism remains unclear. This study examined the effect of dexamethasone on the pharmacokinetics of sunitinib and its metabolite N-desethyl sunitinib in rats. The plasma levels of both compounds were measured using UHPLC-MS/MS. Pharmacokinetic parameters and metabolite ratio values were calculated. Compare to control group, the low-dose dexamethasone group and high-dose dexamethasone group decreased the AUC(0-t) values of sunitinib by 47 % and 45 %, respectively. Meanwhile, the AUC(0-t) values of N-desethyl sunitinib were increased by 2.2-fold and 2.4-fold in low-dose dexamethasone group and high-dose dexamethasone group, respectively. The CL values for sunitinib were both approximately 45 % higher in the two dexamethasone groups. Remarkably, metabolite ratio values increased over 5-fold in both low-dose dexamethasone group and high-dose dexamethasone group, indicating a significant enhancement of sunitinib metabolism by dexamethasone. Moreover, the total levels of sunitinib and its metabolite are also significantly increased. The impact of interactions on sunitinib metabolism, as observed with CYP3A inducers such as dexamethasone, is a crucial consideration for clinical practice. To optimize the dosage and prevent adverse drug events, therapeutic drug monitoring can be employed to avoid the toxicity from such interactions.

PDZK1 confers sensitivity to sunitinib in clear cell renal cell carcinoma by suppressing the PDGFR-β pathway

BACKGROUND

Sunitinib has emerged as the primary treatment for advanced or metastatic clear cell renal cell carcinoma (ccRCC) due to its significant improvement in patients' average survival time. However, drug resistance and adverse effects of sunitinib pose challenges to its clinical benefits.

METHODS

The differentially expressed genes (DEGs) associated with sunitinib sensitivity and resistance in ccRCC were investigated. Cell counting kit-8, plate colony formation, flow cytometry and subcutaneous xenograft tumor model assays were employed to explore the effects of PDZK1 on ccRCC. Further research on the molecular mechanism was conducted through western blot, co-immunoprecipitation, immunofluorescence co-localization and immunohistochemical staining.

RESULTS

We elucidated that PDZK1 is significantly downregulated in sunitinib-resistant ccRCC specimens, and PDZK1 negatively regulates the phosphorylation of PDGFR-β and the activation of its downstream pathways through interaction with PDGFR-β. The dysregulated low levels of PDZK1 contribute to inadequate inhibition of cell proliferation, tumor growth, and insensitivity to sunitinib treatment. Notably, our preclinical investigations showed that miR-15b antagomirs enhance sunitinib cytotoxic effects against ccRCC cells by upregulating PDZK1 levels, suggesting their potential in overcoming sunitinib resistance.

CONCLUSIONS

Our findings establish the miR-15b/PDZK1/PDGFR-β axis as a promising therapeutic target and a novel predictor for ccRCC patients' response to sunitinib treatment.

An oncogenic role of lncRNA SNHG1 promotes ATG7 expression and autophagy involving tumor progression and sunitinib resistance of Renal Cell Carcinoma

Renal cell carcinoma (RCC) is a malignant tumor with high incidence in adult kidney. Long non-coding RNAs (lncRNAs) have recently been recognized as important regulators in the development of RCC. However, whether lncRNA SNHG1 is associated with RCC progression remains to be elucidated. Here, the role of SNHG1 in RCC autophagy and sunitinib resistance was evaluated. Expression of SNHG1 in RCC tissues and cells was assessed using RT-qPCR. Western blot was utilized to measure the levels of autophagy-related molecules and ATG7. RNA pull-down and RIP assays were performed to confirm the molecular axis between SNHG1/PTBP1/ATG7. Cell proliferation, migration, invasion and apoptosis were analyzed by CCK-8, EdU, transwell and flow cytometry, respectively. The subcellular localization of SNHG1 was determined by an intracellular fractionation assay. The fluorescence intensity of GFP-LC3 autophagosome in RCC cells was detected. IHC staining was performed to test ATG7 expression in tumor tissues from nude mice. Here, a positive correlation of upregulated SNHG1 with poor prognosis of RCC patients was observed in RCC tissues and cells. SNHG1 knockdown suppressed tumor growth and reversed sunitinib resistance and autophagy of RCC cells. Additionally, SNHG1 was found to directly bind to PTBP1, thereby positively regulating ATG7 expression. Furthermore, we verified that SNHG1 mediated the malignant behavior of RCC cells through the PTBP1/ATG7 axis. To sum up, SNHG1 regulates RCC cell autophagy and sunitinib resistance through the PTBP1/ATG7 axis, which highlights a promising therapeutic target for RCC treatment.

Hemodialysis and imatinib: Plasma levels, efficacy and tolerability in a patient with metastatic GIST - Case report

Purpose

To study plasma levels, efficacy and tolerability of imatinib in a patient affected by metastatic GIST treated with oral Imatinib and undergoing hemodialysis.

Patients and methods

The patient suffered from metastatic GIST to the liver having a mutation of exon 9 of KIT. He was on hemodialysis and received first-line treatment with imatinib 400 mg/day.

Results

The overall mean plasma level of imatinib was 1875,4 ng/ml pre-dialysis, 1553,0 ng/ml post-dialysis and 1998,1 ng/ml post-24h. In red blood cells the overall mean level of imatinib was 619,5 ng/ml pre-dialysis, 484,9 ng/ml post-dialysis and 663,1 ng/ml post-24h. The plasma level of nor-imatinib/imatinib was 16,2% pre-dialysis, 15,6% post-dialysis and 16,4% post-24h. Comparing our findings regarding levels of imatinib in plasma and RBC, we found a statistically significant difference between pre-dialysis and post-dialysis (respectively p < 0,001 and p = 0,002), post-dialysis and post-24h (both p < 0,001), pre-dialysis and post-24h (respectively p = 0.035 and p = 0,042). Ultimately, regarding nor-imatinib/imatinib in plasma, we did not find any statistically significant difference between pre-dialysis and post-dialysis (p = 0,091), post-dialysis and post-24h (p = 0,091), pre-dialysis and post-24h (p = 0.903). Currently the patient is receiving oral imatinib 400 mg/day with radiological evidence of response.

Conclusion

In this case, hemodialysis did not affect significantly imatinib plasma levels. The statistically significant difference between pre- and post-dialysis can be explained by the fact that dialysis may likely contribute to a small portion of the normal metabolism of imatinib. The evaluation of imatinib levels in RBC and of its main metabolite in plasma also suggests that hemodialysis did not affect other aspects of the elimination of the drug.

An Optimized LC-MS/MS Method for Quantification of Sunitinib and N -Desethyl Sunitinib in Human Plasma and Its Application for Therapeutic Drug Monitoring

BACKGROUND

Sunitinib (SUN) malate is an oral, multitargeted, tyrosine kinase inhibitor approved for the treatment of metastatic renal cell carcinoma, imatinib-resistant or imatinib-intolerant gastrointestinal stromal tumors, and pancreatic neuroendocrine tumors. SUN has a narrow therapeutic window and high variability in interpatient pharmacokinetic parameters. Clinical detection methods for SUN and N -desethyl SUN limit the application of SUN to therapeutic drug monitoring. All published methods for quantifying SUN in human plasma require strict light protection to avoid light-induced isomerism or the use of additional quantitative software. To avoid these difficult processes in clinical routines, the authors propose a novel method that merges the peaks of the E -isomer and Z -isomer of SUN or N -desethyl SUN into a single peak.

METHODS

The E -isomer and Z -isomer peaks of SUN or N -desethyl SUN were merged into a single peak by optimizing the mobile phases to decrease the resolution of the isomers. A suitable chromatographic column was selected to obtain a good peak shape. Thereafter, the conventional and single-peak methods (SPM) were simultaneously validated and compared according to the guidelines published by the Food and Drug Administration in 2018 and the Chinese Pharmacopoeia in 2020.

RESULTS

The verification results showed that the SPM was superior to the conventional method in the matrix effect and met the requirements for biological sample analysis. SPM was then applied to detect the total steady-state concentration of SUN and N -desethyl SUN in tumor patients who received SUN malate.

CONCLUSIONS

The established SPM makes the detection of SUN and N -desethyl SUN easier and faster without light protection or extra quantitative software, making it more appropriate for routine clinical use. The clinical application results showed that 12 patients took 37.5 mg per day, with a median total trough steady-state concentration of 75.0 ng/mL.

miRNA-381 regulates renal cancer stem cell properties and sunitinib resistance via targeting SOX4

Cancer stem cells (CSCs) are crucial in the pathogenesis of human cancers. Existing studies reported that microRNA (miRNA) modulates the stemness of CSCs. We discovered that renal cell CSCs have suppressed miR-381. Suppression of miR-381 promotes renal cell tumorigenesis and CSC-like properties. Furthermore, the forced expression of miR-381 prevents the renal cell tumorigenesis and CSC-like properties. Mechanistically, renal cell CSCs have been found to interact with SOX4 through miR-381 directly. miR-381 inhibits renal cell CSC-like properties and tumorigenesis via downregulating SOX4. Examination of the patient-derived xenografts (PDX) and patient cohorts reveals that miR-381 may be able to forecast the advantages of Sunitinib in RCC patients. Moreover, the introduction of SOX4 could reverse the sensitivity of miR-381 overexpression RCC cells to Sunitinib-induced cell apoptosis. These results indicated that miR-381 is critical in renal cell CSC-like properties and tumorigenesis, making it the ideal therapeutic target for RCC.

Dose Individualization of Oral Multi-Kinase Inhibitors for the Implementation of Therapeutic Drug Monitoring

Oral multi-kinase inhibitors have transformed the treatment landscape for various cancer types and provided significant improvements in clinical outcomes. These agents are mainly approved at fixed doses, but the large inter-individual variability in pharmacokinetics and pharmacodynamics (efficacy and safety) has been an unsolved clinical issue. For example, certain patients treated with oral multi-kinase inhibitors at standard doses have severe adverse effects and require dose reduction and discontinuation, yet other patients have a suboptimal response to these drugs. Consequently, optimizing the dosing of oral multi-kinase inhibitors is important to prevent over-dosing or under-dosing. To date, multiple studies on the exposure-efficacy/toxicity relationship of molecular targeted therapy have been attempted for the implementation of therapeutic drug monitoring (TDM) strategies. In this milieu, we recently conducted research on several multi-kinase inhibitors, such as sunitinib, pazopanib, sorafenib, and lenvatinib, with the aim to optimize their treatment efficacy using a pharmacokinetic/pharmacodynamic approach. Among them, sunitinib use is an example of successful TDM implementation. Sunitinib demonstrated a significant correlation between drug exposure and treatment efficacy or toxicities. As a result, TDM services for sunitinib has been covered by the National Health Insurance program in Japan since April 2018. Additionally, other multi-kinase targeted anticancer drugs have promising data regarding the exposure-efficacy/toxicity relationship, suggesting the possibility of personalization of drug dosage. In this review, we provide a comprehensive summary of the clinical evidence for dose individualization of multi-kinase inhibitors and discuss the utility of TDM of multi-kinase inhibitors, especially sunitinib, pazopanib, sorafenib, and lenvatinib.

Sunitinib-Induced Elevation of Mean Corpuscular Volume (MCV)-Exploring Its Possible Clinical Relevance in Cancer Patients

Sunitinib is a broad-spectrum multitargeted tyrosine kinase inhibitor mainly used as second-line therapy for non-resectable gastrointestinal stromal or first-line treatment option of metastatic renal cell carcinoma (mRCC), and as an “off-label” option in pediatric oncology. It has been previously reported that sunitinib elevates the mean corpuscular volume of erythrocytes (MCV) in treated subjects. The aim of this study was to assess time-dependent changes of this effect and evaluate its possible clinical relevance. In this study, 179 adult and 21 pediatric patients with solid tumors treated with sunitinib were retrospectively analyzed. The laboratory and treatment-related data were collected for each treatment period. The regression model with a broken-line relationship was used to fit time dependence of the MCV. In the adult group, the MCV was increasing during the first 21.6 weeks (median) of treatment in a median level of 99.8 fL, where it stabilized. MCV increase was faster in the patients who suffered from treatment-related adverse events (21.3 vs. 24.6 weeks, p = 0.010). In the pediatric cohort, the MCV dynamics were similar to adults. In conclusion, MCV changes during sunitinib treatment in pediatric and adult patients may be of clinical utility in monitoring sunitinib treatment course.

Feasibility of therapeutic drug monitoring of sunitinib and its implications on response and toxicity in patients with metastatic renal cell cancer

PURPOSE

Sunitinib is an oral tyrosine kinase inhibitor approved for the treatment of metastatic renal cell carcinoma (mRCC). High variability in pharmacokinetics coupled with a proven exposure-effect relationship makes sunitinib an ideal candidate for therapeutic drug monitoring (TDM). The feasibility of TDM of sunitinib in patients with mRCC was evaluated in this prospective observational study in a real-world scenario.

METHODS

Seventy patients with mRCC treated with sunitinib at a fixed dose of 50 mg per day were enrolled in the study. Total trough plasma level (TTL) of sunitinib (sunitinib and its active metabolite, SU12662), was measured between days 14/15 of cycle 1. The discriminatory potential of TTL of sunitinib for the prediction of responders and occurrence of grade ≥ 3 toxicity was determined using receiver operating characteristic (ROC) curve.

RESULTS

The median TTL of sunitinib was 76 ng/mL. Forty six out of 70 patients were evaluable for response, whereas 60 out of 70 patients were evaluable for toxicity. Threshold concentrations obtained from ROC analysis showed that TTL of 60.75 ng/mL and 82.3 ng/mL was discriminatory for response and occurrence of grade ≥ 3 toxicity respectively. 31/34 (91.7%) patients having TTL ≥ 60.75 ng/mL responded to treatment, while only 5/12 (41.6%) responded when TTL was < 60.75 ng/mL (P = 0.001). On the other hand, the incidence of grade ≥ 3 toxicity was 9/24 (37.7%) in patients with TTL ≥ 82.3 ng/mL compared to 4/36 (11.1%) in patients with TTL < 82.3 ng/mL (P = 0.024).

CONCLUSION

The TTL range of 60.75-82.3 ng/mL was found to be optimal in terms of safety and efficacy. More than 50% of patients in our cohort attained TTL of sunitinib outside the optimal range, thus demonstrating the feasibility of TDM to improve safety and efficacy of sunitinib in mRCC.

Systematic review and cost-effectiveness of pharmacokinetically guided sunitinib individualized treatment for patients with metastatic renal cell carcinoma

Background:

Sunitinib has a narrow therapeutic window, with considerable differences between patients. Dosing based on pharmacokinetics (PK) may help overcome some of those issues. This study aims to evaluate and compare the cost-effectiveness of PK-guided individualized treatment of sunitinib with its standard dose in patients with metastatic renal cell carcinoma (mRCC).

Methods:

A comprehensive literature search was performed, and relevant values were used to provide information for the decision analysis model. Utility data were derived from published studies, and costs were obtained from the perspective of payers in China and the United States. A Markov model was established to evaluate the associated costs and health outcomes for patients. The primary outputs of the model included lifetime costs, quality-adjusted life years (QALYs), and incremental cost-effectiveness ratio (ICER). One-way and probability sensitivity analyses were conducted to evaluate the potential uncertainties of parameters.

Results:

Cost-effective analysis showed that the QALY of the PK-guided group increased by 0.83 compared with that in the standard dose group. From the perspective of both countries’ health systems, the cost of PK-guided dose was lower than that of standard dose. Hence, PK-guided treatment was the dominant strategy. One-way and probability sensitivity analyses confirmed the reliability of these results.

Conclusion:

On the basis of currently available data, PK-guided sunitinib treatment may be a safe, effective, and economical intervention for patients with mRCC.

Synthesis and Characterization of Novel Copper(II)-Sunitinib Complex: Molecular Docking, DFT Studies, Hirshfeld Analysis and Cytotoxicity Studies

The main goal of this work was to report the synthesis, characterization, and cytotoxicity study of a novel copper(II)-sunitinib complex, CuSun. It has been synthesized and characterized in solid state and in solution by different methods (such as DFT, FTIR, Raman, UV-vis, EPR, NMR, etc.). The solid-state molecular structure of trichlorosunitinibcopper(II), where sunitinib: N-[2-(diethylamino)ethyl]-5-[(Z)-(5-fluoro-2-oxo-1H-indol-3-ylidene)methyl]-2,4-dimethyl-1H-pyrrole-3-carboxamide, for short Cu(Sun)Cl3, was determined by X-ray diffraction. It crystallizes in the triclinic space group P-1 with a = 7.9061(5) Å, b = 12.412(1) Å, c = 13.7005(8) Å, α = 105.021(6)°, β = 106.744(5)°, γ = 91.749(5)°, and Z = 2 molecules per unit cell. Also, we have found π-π interactions and classic and non-classic H-bonds in the crystal structure by using Hirshfeld surface analysis. In the speciation studies, the complex has dissociated in protonated sunitinib and chlorocomplex of copper(II), according to 1HNMR, EPR, UV-vis and conductimetric analysis. Molecular docking of the complex in both, ATP binding site and allosteric site of VEGFR2 have shown no improvement in comparison to the free ligand. Besides, cytotoxicity assay on HepG2 cell line shows similar activity for complex and ligand in the range between 1–25 μM supporting the data obtained from studies in solution.

Clinical-Based vs. Model-Based Adaptive Dosing Strategy: Retrospective Comparison in Real-World mRCC Patients Treated with Sunitinib

Different target exposures with sunitinib have been proposed in metastatic renal cell carcinoma (mRCC) patients, such as trough concentrations or AUCs. However, most of the time, rather than therapeutic drug monitoring (TDM), clinical evidence is preferred to tailor dosing, i.e., by reducing the dose when treatment-related toxicities show, or increasing dosing if no signs of efficacy are observed. Here, we compared such empirical dose adjustment of sunitinib in mRCC patients, with the parallel dosing proposals of a PK/PD model with TDM support. In 31 evaluable patients treated with sunitinib, 53.8% had an empirical change in dosing after treatment started (i.e., 46.2% decrease in dosing, 7.6% increase in dosing). Clinical benefit was observed in 54.1% patients, including 8.3% with complete response. Overall, 58.1% of patients experienced treatment discontinuation eventually, either because of toxicities or progressive disease. When choosing 50-100 ng/mL trough concentrations as a target exposure (i.e., sunitinib + active metabolite N-desethyl sunitinib), 45% patients were adequately exposed. When considering 1200-2150 ng/mL.h as a target AUC (i.e., sunitinib + active metabolite N-desethyl sunitinib), only 26% patients were in the desired therapeutic window. TDM with retrospective PK/PD modeling would have suggested decreasing sunitinib dosing in a much larger number of patients as compared with empirical dose adjustment. Indeed, when using target trough concentrations, the model proposed reducing dosing for 61% patients, and up to 84% patients based upon target AUC. Conversely, the model proposed increasing dosing in 9.7% of patients when using target trough concentrations and in 6.5% patients when using target AUC. Overall, TDM with adaptive dosing would have led to tailoring sunitinib dosing in a larger number of patients (i.e., 53.8% vs. 71-91%, depending on the chosen metrics for target exposure) than a clinical-based decision. Interestingly, sunitinib dosing was empirically reduced in 41% patients who displayed early-onset severe toxicities, whereas model-based recommendations would have immediately proposed to reduce dosing in more than 80% of those patients. This observation suggests that early treatment-related toxicities could have been partly avoided using prospective PK/PD modeling with adaptive dosing. Conversely, the possible impact of model-based adapted dosing on efficacy could not be fully evaluated because no clear relationship was found between baseline exposure levels and sunitinib efficacy measured at 3 months.

Individualized Management of Blood Concentration in Patients with Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor, and surgical resection is the first choice for the treatment of the disease, but since the advent of tyrosine kinase inhibitors (TKIs) such as imatinib (IM), the prognosis of the disease has undergone revolutionary changes. According to the current version of the guidelines, most GIST patients receive a fixed dose without taking into account their own individual differences, resulting in a wide difference in blood concentration, adverse reactions and prognosis. With more studies on the relationship between blood drug concentrations and prognosis, the concept of individualized therapy has been paid more attention by researchers. Therapeutic drug monitoring (TDM) has also been made available for the research field of GIST targeted therapy. How to reduce the incidence of drug resistance and adverse reactions in patients with GISTs has become the focus of the current research. This article reviews the common monitoring methods and timing of TKIs blood concentration, the reasonable range of blood drug concentration, the toxic or adverse effects caused by high blood drug concentration, some possible factors affecting blood drug concentration and recent research progress, in order to discuss and summarize the treatment strategy of individual blood drug concentration, improve the prognosis of patients and reduce the adverse effects as much as possible.

Sunitinib malate inhibits intestinal tumor development in male ApcMin/+ mice by down-regulating inflammation-related factors with suppressing β-cateinin/c-Myc pathway and re-balancing Bcl-6 and Caspase-3

Sunitinib is a tyrosine kinase inhibitor for many tumors. Inflammation is one of the most important factors in the development of intestinal tumors. Many inflammation-related factors are regulated by tyrosine kinase receptors. It is reasonable to hypothesize that sunitinib can regulate the development of intestinal tumors by regulating the expression and/or activity of inflammation-related factors. Here, ApcMin/+ male mouse model was used to investigate the effect and mechanism of sunitinib malate against intestinal cancer. Results show that compared to vehicle, after sunitinib malate treatment, overall survival of ApcMin/+ mice was lengthened up to 25 days, with a gain of body weight, reduction of spleen/body weight index, and RBC, WBC and HGC regulated to normal levels of wild type mice, and a number of polyps no less than 1 mm significantly reduced. Meanwhile, in the intestines, the nuclear β-Catenin protein and c-Myc mRNA were both down-regulated, and Bcl-6 was significantly reduced with Caspase-3 up regulated. Furthermore, inflammation-related factors including IL-6, TNF-α, IL-1α, IL-1β and IFN-γ were down-regulated at mRNA levels in the intestines. These results suggest that sunitinib malate can significantly improve the survival status and inhibit intestinal tumor development in male ApcMin/+ mice, through inhibiting inflammation-related factors, while suppressing β-cateinin/c-Myc pathway and re-balancing protein levels of Bcl-6 and Caspase-3.

Revolutions in treatment options in gastrointestinal stromal tumours (GISTs): the latest updates

OPINION STATEMENT

The treatment of advanced GIST is rapidly evolving with the development of novel molecular compounds such as avapritinib and ripretinib, but also promising results have been achieved with cabozantinib in a phase II trial. The availability of over five lines of treatment for patients with advanced GIST is likely to completely shift the current second-line and third-line treatment options, and will also potentially enable a personalised approach to treatment. Imatinib will most likely remain as the first-line treatment of choice for the vast majority of GIST patients. However, for GIST patients with tumours harbouring a D842V mutation in PDGFRA exon 18, avapritinib has shown efficacy and will become first-line therapy for this molecular subgroup. For second- and third-line treatment, results are awaited of a number of clinical trials. However, second-line and further treatment could potentially be tailored depending on secondary mutations found in imatinib-resistant GISTs. As secondary resistance to TKIs remains the biggest challenge in the treatment of GIST and despite negative results with alternating regimens in phase II, combination treatments should be further evaluated to tackle this issue. Moreover, the favourable safety profiles observed with avapritinib and ripretinib suggest that combination treatments are feasible, for instance, combining two TKIs or a TKI with drugs targeting downstream signalling pathways, such as PI3K inhibitors or MEK inhibitors. Finally, in line with further personalisation of treatment in GIST, a multidisciplinary approach is essential, and local treatment options, such as RFA, resection in case of unifocal progression, and radiotherapy, should be considered.