Association of Plasma Cabozantinib Concentration With Treatment Response and Adverse Events in Japanese Patients With Advanced Renal Cell Carcinoma.

BACKGROUND: Cabozantinib is highly effective against advanced renal cell carcinoma (RCC). However, approximately 60% of the patients require a dose reduction due to severe adverse events. Although associations between trough concentrations of cabozantinib and its efficacy and safety have been reported in other countries, reports on Japanese patients are unavailable. Therefore, we investigated the association of cabozantinib trough concentration with therapeutic efficacy and adverse events in Japanese patients with RCC and evaluated the usefulness of therapeutic drug monitoring. METHODS: In this prospective observational study, we measured the trough concentrations of cabozantinib in 10 Japanese patients with RCC enrolled between May 2022 and September 2023. The associations of trough concentration with treatment response, as determined by RECIST 1.1, and the occurrence of grade 2 or higher adverse events were assessed. RESULTS: Trough concentration was higher in patients with controlled cancer than in those with progressive cancer (1024 ± 352 versus 457 ± 216 ng/mL, P = 0.035). In addition, patients with grade 2 or higher adverse events showed a significantly higher trough concentration than those without (1560 ± 513 versus 807 ± 319 ng/mL, P = 0.032). In particular, grade 2 or higher dysgeusia, anorexia, fatigue, and dyspepsia significantly correlated with trough concentrations. CONCLUSIONS: This is the first clinical study to demonstrate a correlation between cabozantinib trough concentration, therapeutic efficacy, and adverse events in Japanese patients with RCC. The therapeutic drug monitoring of cabozantinib could be useful for improving therapeutic efficacy and avoiding serious adverse events.

Quantitative determination of plasma cabozantinib concentration using HPLC-UV and its application to patients with renal cell carcinoma.

Cabozantinib is an oral small-molecule tyrosine kinase inhibitor that has become a standard of care for advanced renal cell carcinoma (RCC). However, cabozantinib is associated with a high rate of adverse events. Therefore, individualised cabozantinib administration and monitoring could help maximise its therapeutic efficacy and avoid serious adverse events. This study developed and validated a method to determine cabozantinib concentration in plasma using HPLC-UV. Sorafenib, an internal standard, was added to the plasma sample containing cabozantinib. A calibration curve for cabozantinib showed good linearity (R2 = 1.00), between 25 and 4,000 ng/ml. The recovery rate was above 92.1%, and the intra- and inter-day coefficients of variation were smaller than 5.2 and 6.8%, respectively. Then, we applied the method for monitoring cabozantinib blood levels in three patients with advanced RCC who were taking cabozantinib at a dose of 20, 40 or 60 mg/day. Grade 3 adverse events were more likely to occur in patients with high dosing and blood level of cabozantinib. Owing to its simplicity, the developed method can be used in general hospitals, and is expected to help maximise drug efficacy and minimise serious adverse events in many patients with RCC undergoing cabozantinib treatment.

Comparative whole-genome and proteomics analyses of the next seed bank and the original master seed bank of MucoRice-CTB 51A line, a rice-based oral cholera vaccine.

BACKGROUND: We have previously developed a rice-based oral vaccine against cholera diarrhea, MucoRice-CTB. Using Agrobacterium-mediated co-transformation, we produced the selection marker-free MucoRice-CTB line 51A, which has three copies of the cholera toxin B subunit (CTB) gene and two copies of an RNAi cassette inserted into the rice genome. We determined the sequence and location of the transgenes on rice chromosomes 3 and 12. The expression of alpha-amylase/trypsin inhibitor, a major allergen protein in rice, is lower in this line than in wild-type rice. Line 51A was self-pollinated for five generations to fix the transgenes, and the seeds of the sixth generation produced by T5 plants were defined as the master seed bank (MSB). T6 plants were grown from part of the MSB seeds and were self-pollinated to produce T7 seeds (next seed bank; NSB). NSB was examined and its whole genome and proteome were compared with those of MSB. RESULTS: We re-sequenced the transgenes of NSB and MSB and confirmed the positions of the three CTB genes inserted into chromosomes 3 and 12. The DNA sequences of the transgenes were identical between NSB and MSB. Using whole-genome sequencing, we compared the genome sequences of three NSB with three MSB samples, and evaluated the effects of SNPs and genomic structural variants by clustering. No functionally important mutations (SNPs, translocations, deletions, or inversions of genic regions on chromosomes) between NSB and MSB samples were detected. Analysis of salt-soluble proteins from NSB and MSB samples by shot-gun MS/MS detected no considerable differences in protein abundance. No difference in the expression pattern of storage proteins and CTB in mature seeds of NSB and MSB was detected by immuno-fluorescence microscopy. CONCLUSIONS: All analyses revealed no considerable differences between NSB and MSB samples. Therefore, NSB can be used to replace MSB in the near future.

The significance of therapeutic drug monitoring in detecting low medication adherence in patients with cancer: A case study of cabozantinib.

Maintaining good medication adherence is important for providing desirable outcomes from medication therapy. We showed that therapeutic drug monitoring (TDM) contributed to the identification of low medication adherence to cabozantinib in a patient with cancer. We present an educational case to assist with understanding TDM in a patient with cancer.

Preliminary Investigation of a Rapid and Feasible Therapeutic Drug Monitoring Method for the Real-Time Estimation of Blood Pazopanib Concentrations.

Pazopanib is a multi-kinase inhibitor used to treat advanced/metastatic renal cell carcinoma and advanced soft tissue tumors; however, side effects such as diarrhea and hypertension have been reported, and dosage adjustment based on drug concentration in the blood is necessary. However, measuring pazopanib concentrations in blood using the existing methods is time-consuming; and current dosage adjustments are made using the results of blood samples taken at the patient's previous hospital visit (approximately a month prior). If the concentration of pazopanib could be measured during the waiting period for a doctor's examination at the hospital (in approximately 30 min), the dosage could be adjusted according to the patient's condition on that day. Therefore, we aimed to develop a method for rapidly measuring blood pazopanib concentrations (in approximately 25 min) using common analytical devices (a tabletop centrifuge and a spectrometer). This method allowed for pazopanib quantification in the therapeutic concentration range (25-50 µg/mL). Additionally, eight popular concomitant medications taken simultaneously with pazopanib did not interfere with the measurements. We used the developed method to measure blood concentration in two patients and obtained similar results to those measured using the previously reported HPLC method. By integrating it with the point of care and sample collection by finger pick, this method can be used for measurements in pharmacies and patients' homes. This method can maximize the therapeutic effects of pazopanib by dose adjustment to control adverse events.

MucoRice-CTB line 19A, a new marker-free transgenic rice-based cholera vaccine produced in an LED-based hydroponic system.

We previously established the selection-marker-free rice-based oral cholera vaccine (MucoRice-CTB) line 51A for human use by Agrobacterium-mediated co-transformation and conducted a double-blind, randomized, placebo-controlled phase I trial in Japan and the United States. Although MucoRice-CTB 51A was acceptably safe and well tolerated by healthy Japanese and U.S. subjects and induced CTB-specific antibodies neutralizing cholera toxin secreted by Vibrio cholerae, we were limited to a 6-g cohort in the U.S. trial because of insufficient production of MucoRice-CTB. Since MucoRice-CTB 51A did not grow in sunlight, we re-examined the previously established marker-free lines and selected MucoRice-CTB line 19A. Southern blot analysis of line 19A showed a single copy of the CTB gene. We resequenced the whole genome and detected the transgene in an intergenic region in chromosome 1. After establishing a master seed bank of MucoRice-CTB line 19A, we established a hydroponic production facility with LED lighting to reduce electricity consumption and to increase production capacity for clinical trials. Shotgun MS/MS proteomics analysis of MucoRice-CTB 19A showed low levels of α-amylase/trypsin inhibitor-like proteins (major rice allergens), which was consistent with the data for line 51A. We also demonstrated that MucoRice-CTB 19A had high oral immunogenicity and induced protective immunity against cholera toxin challenge in mice. These results indicate that MucoRice-CTB 19A is a suitable oral cholera vaccine candidate for Phase I and II clinical trials in humans, including a V. cholerae challenge study.

Oral MucoRice-CTB vaccine is safe and immunogenic in healthy US adults.

MucoRice-CTB is a promising cold-chain-free oral cholera vaccine candidate. Here, we report a double-blind, randomized, placebo-controlled, phase I study conducted in the USA in which vaccination with the 6-g dose of MucoRice-CTB induced cross-reactive antigen-specific antibodies against the B subunit of cholera toxin (CTB) and enterotoxigenic Escherichia coli heat-labile enterotoxin without inducing serious adverse events. This dosage was acceptably safe and tolerable in healthy men and women. In addition, it induced a CTB-specific IgA response in the saliva of two of the nine treated subjects; in one subject, the immunological kinetics of the salivary IgA were similar to those of the serum CTB-specific IgA. Antibodies from three of the five responders to the vaccine prevented CTB from binding its GM1 ganglioside receptor. These results are consistent with those of the phase I study in Japan, suggesting that oral MucoRice-CTB induces neutralizing antibodies against diarrheal toxins regardless of ethnicity.