Development of an S-1 dosage formula based on renal function by a prospective pharmacokinetic study

Chapter 2:indications and dosing of anticancer drug therapy in patients with impaired kidney function, from clinical practice guidelines for the management of kidney injury during anticancer drug therapy 2022

This comprehensive review discusses the dosing strategies of cancer treatment drugs for patients with impaired kidney function, specifically those with chronic kidney disease (CKD), undergoing hemodialysis, and kidney transplant recipients. CKD patients often necessitate dose adjustments of chemotherapeutic agents, e.g., platinum preparations, pyrimidine fluoride antimetabolites, antifolate agents, molecularly targeted agents, and bone-modifying agents, to prevent drug accumulation and toxicity due to diminished renal clearance of the administered drugs and their metabolites. In hemodialysis patients, factors such as drug removal from hemodialysis and altered pharmacokinetics demand careful optimization of anticancer drug therapy, including dose adjustment and timing of administration. While free cisplatin is removed by hemodialysis, most of the tissue- and protein-bound cisplatin remains in the body and rebound cisplatin elevations are observed after hemodialysis. It is not recommended hemodialysis for drug removal, regardless of timing. Kidney transplant patients encounter unique challenges in cancer treatment, as maintaining the balance between reduction of immunosuppression, switching to mTOR inhibitors, and considering potential drug interactions with chemotherapeutic agents and immunosuppressants are crucial for preventing graft rejection and achieving optimal oncologic outcomes. The review underscores the importance of personalized, patient-centric approaches to anticancer drug therapy in patients with impaired kidney function.

Evaluation of clinical validity of an S-1 dosage formula based on renal function using data of the SPIRITS and the G-SOX trials

BACKGROUND

The aim of this study was to evaluate clinical validity of the S-1 dosage formula based on body surface area (BSA) and creatinine clearance (CLcr) to achieve the target area under the concentration-time curve of 5-FU, which we had developed and refined in each prospective pharmacokinetic study.

METHODS

The recommended dose determined by the refined formula was assessed using data of the SPIRITS (S-1 vs. S-1 plus cisplatin [SP]) and the G-SOX (SP vs. S-1 plus oxaliplatin [SOX]) trials. Nine hundred and thirty-eight patients in these trials were classified into three groups according to their actual S-1 starting doses compared with the recommended doses (under-dosed, <recommended dose; equal-dosed, =recommended dose; over-dosed, >recommended dose).

RESULTS

The patients in the under-dosed group in both trials showed similar tendencies: male, younger, higher BSA, and higher CLcr. The incidence of any grade neutropenia was significantly greater in the over-dosed group compared with the equal-dosed group in the S-1 and the SOX arms. The hazard ratios (HR) of overall survival (OS) (under-dosed vs. equal-dosed) were 1.361 (S-1 arm), 1.259 (SP arm) in the SPIRITS trial, and 1.381 (SOX arm), 0.999 (SP arm) in the G-SOX trial. Multivariate analysis in all the patients demonstrated that OS of the over-dosed group was equivalent (HR 1.002, 95% confidence interval [CI] 0.850-1.182, p = 0.980) and that of the under-dosed group was inferior (HR 1.267, 95% CI 1.005-1.597, p = 0.045) to the equal-dosed group.

CONCLUSIONS

It is suggested that the refined S-1 dosage formula can recommend optimal dose in terms of safety and efficacy.

Usefulness of an S-1 dosage formula: an exploratory analysis of randomized clinical trial (JCOG1001)

BACKGROUND

The blood concentration of S-1 and adverse events are affected by renal function. Herein, an S-1 dosage formula was developed based on renal function, indicating the dose for a target blood concentration. This study aimed to explore the usefulness of the formula in adjuvant chemotherapy for gastric cancer.

METHODS

In this ad hoc analysis of the JCOG1001 trial, which evaluated the role of bursectomy for resectable gastric cancer, the recommended dose of S-1 was calculated using the following formula: 1447.8 × (14.5 + 0.301 × CLcr + 8.23 × SEX [male = 1, female = 0]) × body surface area (BSA) (mg/day). Patients were divided into three groups by comparing the initial S-1 dose determined using BSA with the dose recommended by the formula: underdose (UD), equal dose (ED), and overdose (OD).

RESULTS

Among 686 eligible patients, 58, 304, and 324 patients were classified into the UD, ED, and OD groups. The patients' characteristics in the UD/ED/OD groups were median age (53.5/64.0/67.5 years), male sex (98.3%/75.3%/58.0%), and median BMI (24.8/22.8/22.3), respectively. The planned 1-year adjuvant S-1 therapy was completed in 74.1%/73.7%/68.5%, dose reduction was required in 8.6%/21.1%/30.6%, and treatment schedule was altered in 8.6%/17.1/19.8% in the UD/ED/OD groups, resulting in the 5-year overall survival rates of 77.3%/74.3%/77.0%, respectively. The incidences of grade > 3 anemia, thrombocytopenia, diarrhea, stomatitis, and anorexia were significantly higher in the OD group than in the ED and UD groups.

CONCLUSIONS

Dose optimization using an S-1 dosage formula can potentially reduce grade ≥ 3 adverse events for overdosed patients.

Association of renal function with the safety and efficacy of cisplatin plus S-1 therapy and docetaxel plus cisplatin plus S-1 therapy in patients with advanced gastric cancer: an exploratory analysis of JCOG1013

BACKGROUND

Although cisplatin and 5-chloro-2,4-dihydropyrimidine (dihydropyrimidine dehydrogenase inhibitor contained in S-1) are excreted into the urine, it remains unknown how creatinine clearance (CrCl) affects the safety and efficacy of cisplatin plus S-1 and docetaxel plus cisplatin plus S-1 in patients with advanced gastric cancer.

METHODS

Among the 741 participants in JCOG1013 comparing cisplatin plus S-1 with docetaxel plus cisplatin plus S-1, 723 with serum creatinine levels ≤1.2 mg/dL were categorized into A1 (CrCl ≥ 80 mL/min), A2 (60 ≤ CrCl <80) and A3 (CrCl < 60) in the cisplatin plus S-1 arm and similarly B1, B2 and B3 in the docetaxel plus cisplatin plus S-1 arm. The initial dose modification by CrCl was pre-specified in the docetaxel plus cisplatin plus S-1 arm but not in the cisplatin plus S-1 arm.

RESULTS

The numbers of patients categorized as A1/A2/A3 and B1/B2/B3 were 169/136/57 and 170/138/53, respectively. In the cisplatin plus S-1 arm, a lower CrCl was associated with higher incidences of grade 4 leukopenia (P = 0.006), neutropenia (P = 0.002), and grade 3/4 anorexia (P = 0.004) and febrile neutropenia (P = 0.049), whereas there was no association in the docetaxel plus cisplatin plus S-1 arm. No significant differences were observed according to CrCl in the overall survival [median: 15.4/15.5/15.4 months in A1/A2/A3 (P = 0.886) and 15.3/13.7/13.7 months in B1/B2/B3 (P = 0.719)], progression-free survival [median: 7.1/6.8/6.2 months in A1/A2/A3 (P = 0.884) and 7.5/7.2/7.8 months in B1/B2/B3 (P = 0.851)] and response rates [58.9/57.8/46.9% in A1/A2/A3 (P = 0.311) and 62.0/61.5/51.5% in B1/B2/B3 (P = 0.362)].

CONCLUSIONS

Renal impairment was associated with severe adverse events in cisplatin plus S-1 therapy but not with the efficacy in cisplatin plus S-1 and docetaxel plus cisplatin plus S-1 therapy.

Comparison of gemcitabine-based chemotherapies for advanced biliary tract cancers by renal function: an exploratory analysis of JCOG1113

JCOG1113 is a randomized phase III trial in patients with advanced biliary tract cancers (BTCs) (UMIN000001685), and gemcitabine plus S-1 (GS) was not inferior to gemcitabine plus cisplatin (GC). However, poor renal function often results in high toxicity of S-1. Therefore, we examined whether GS can be recommended for patients with low creatinine clearance (CCr). Renal function was classified by CCr as calculated by the Cockcroft-Gault formula: high CCr (CCr ≥ 80 ml/min) and low CCr (80 > CCr ≥ 50 ml/min). Of 354 patients, 87 patients on GC and 91 on GS were included in the low CCr group, while there were 88 patients on GC and 88 patients on GS in the high CCr group. The HR of overall survival for GS compared with GC was 0.687 (95% CI 0.504–0.937) in the low CCr group. Although the total number of incidences of all Grade 3–4 non-haematological adverse reactions was higher (36.0% vs. 11.8%, p = 0.0002), the number of patients who discontinued treatment was not different (14.1% vs. 16.9%, p = 0.679) for GS compared with GC in the low CCr group. This study suggests that GS should be selected for the treatment of advanced BTC patients with reduced renal function.

Prospective evaluation and refinement of an S-1 dosage formula based on renal function for clinical application

In patients with impaired renal function, S-1-related toxicities increase due to higher exposure of 5-fluorouracil (5-FU). Our previous pharmacokinetic study in 16 cancer patients with various renal functions developed an S-1 dosage formula based on individual creatinine clearance (CLcr) and body surface area (BSA). To evaluate and refine the formula, this prospective study was conducted. Thirty-three patients with various renal functions received S-1 for 4 weeks at doses determined by the nomogram derived from the previously developed formula. A series of blood samples were collected after the first dose to calculate the area under the concentration-time curve (AUC) of 5-FU. Thirty patients with BSA of 1.14-1.84 m² and CLcr of 23.8-96.4 mL/min were assessable for pharmacokinetics. The observed daily AUC ranged from 712.6 to 2868.7 ng·h/mL, and 18 patients achieved the target AUC (1447.8 ± 545.4 ng·h/mL). Three patients experienced S-1-related grade 3 adverse events during the first course. In the population pharmacokinetic analysis from the combined data of 46 patients in this study and the previous study, sex was identified as a statistically significant covariate for 5-FU clearance. Hence, the refined formula includes sex as an additional factor: Recommended daily dose = target AUC × (14.5 + 8.23 × SEX [0 for female and 1 for male] + 0.301 × CLcr) × BSA. Revised nomograms for recommended daily doses derived from the refined formula can be used in clinical practice to achieve the target AUC ensuring efficacy and safety of S-1.

Pharmacokinetic study of the oral fluorouracil antitumor agent S-1 in patients with impaired renal function

Although dose reduction of S-1 is recommended for patients with impaired renal function, dose modification for such patients has not been prospectively evaluated. The aim of the present study was to investigate the pharmacokinetic parameters of 5-fluorouracil, 5-chloro-2,4 dihydroxypyridine and oteracil potassium, and to review the recommended dose modification of S-1 in patients with renal impairment. We classified patients receiving S-1 into 4 groups according to their renal function, as measured using the Japanese estimated glomerular filtration rate (eGFR) equation. The daily S-1 dose was adjusted based on the patient's eGFR and body surface area. Blood samples were collected for pharmacokinetic analysis. A total of 33 patients were enrolled and classified into 4 groups as follows: 10 patients in cohort 1 (eGFR ≥ 80 mL/min/1.73 m² ), 10 patients in cohort 2 (eGFR = 50-79 mL/min/1.73 m² ), 10 patients in cohort 3 (eGFR = 30-49 mL/min/1.73 m² ), and 3 patients in cohort 4 (eGFR < 30 mL/min/1.73 m² ). Those in cohorts 3 and 4 treated with an adjusted dose of S-1 showed a similar area under the curve for 5-fluorouracil (941.9 ± 275.6 and 1043.5 ± 224.8 ng/mL, respectively) compared with cohort 2 (1034.9 ± 414.3 ng/mL). Notably, while there was a statistically significant difference between cohort 1 (689.6 ± 208.8 ng/mL) and 2 (P = 0.0474) treated with an equal dose of S-1, there was no significant difference observed in the toxicity profiles of the cohorts. In conclusion, dose adjustment of S-1 in patients with impaired renal function using eGFR is appropriate and safe.

A high throughput immunoassay for the therapeutic drug monitoring of tegafur

Cancer is a group of diseases in which abnormal cells grow and divide without control, with the potential to invade other parts of the body. Chemotherapy is a type of treatment that uses chemical agents to treat cancer. These drugs are toxic and produce undesirable adverse drug reactions due to their narrow therapeutic window and highly variable pharmacokinetics, thus, they need to be monitored to establish personalized treatment to achieve maximal efficiency and reduce drug toxicity. Nowadays, therapeutic drug monitoring (TDM) is not routinely used for chemotherapy agents, however, TDM has the potential to improve the clinical benefit of chemotherapy drugs. Tegafur, a prodrug of 5-fluorouracil (5FU), is one of the main anti-cancer drugs used worldwide. Herein, a reproducible and sensitive indirect competitive ELISA has been developed and validated in plasma samples. The assay reports an IC₅₀ of 35.6 nM, reaching a limit of detection of 2.7 nM. It is highly reproducible and does not show cross-reactivity with any related compound. In summary, this assay provides a sensitive, accurate and high throughput analytical method for tegafur quantification in plasma, which fits TDM requirements.

Effect of combined treatment with micelle-incorporated cisplatin (NC-6004) and S-1 on human gastric cancer xenografts

Combination therapy with S-1 and cisplatin (CDDP) is the standard chemotherapy for advanced gastric cancer in Japan; however, its administration requires hospitalization for hydration to prevent nephrotoxicity from CDDP. By contrast, NC-6004 appears to reduce the renal toxicity of CDDP and may be used on an outpatient basis. Thus, the effects of combined treatment with S-1 and NC-6004 were compared with those of S-1 and CDDP in a human gastric cancer model. In vitro cytotoxic effects were investigated in 44As3Luc, MKN45 and MKN74 human gastric cancer cell lines. The effects of NC-6004 and 5-fluorouracil (5-FU) were compared with the effects of CDDP and 5-FU using the combination index method. The in vivo antitumor effects of S-1/NC-6004 and S-1/CDDP were evaluated in mice bearing 44As3Luc xenografts. Both combinations exhibited synergistic activity in MKN45 and MKN74 cells and additive effects in 44As3Luc cells. Moreover, the in vivo antitumor effects did not differ between the S-1/NC-6004 and S-1/CDDP treatment groups. However, a significantly lower body weight loss was observed in S-1/NC-6004-treated mice compared with the S-1/CDDP-treated mice. Our data warrant a clinical evaluation of S-1/NC-6004 combination therapy.