Quantitative determination of erlotinib in human serum using competitive enzyme-linked immunosorbent assay

A selective and sensitive competitive enzyme-linked immunosorbent assay(ELISA) method was developed and validated for the quantification of erlotinib in 50 mL of samples of human serum. Anti-erlotinib serum was obtained by immunizing mice with an antigen conjugated with bovine serum albumin and 3,4-bis(2-methoxyethoxy)benzoic acid using the N-succinimidyl ester method. Enzyme labeling of erlotinib with horseradish peroxidase was similarly performed using 3,4-bis(2-methoxyethoxy)benzoic acid. A simple competitive ELISA for erlotinib was developed using the principle of direct competition between erlotinib and the enzyme marker for anti-erlotinib antibody, which had been immobilized on the plastic surface of a microtiter plate. Serum erlotinib concentrations lower than 40 ng/mL were reproducibly measurable using the ELISA. This ELISA was specific to erlotinib and showed very slight cross-reactivity(6.7%) with a major metabolite, O-desmethyl erlotinib. Using this assay, drug levels were easily measured in the blood of mice after oral administration of erlotinib at a single dose of 30 mg/kg. ELISA should be used as a valuable tool for therapeutic drug monitoring and in pharmacokinetic studies of erlotinib.

Review of epidermal growth factor receptor-tyrosine kinase inhibitors administration to non-small-cell lung cancer patients undergoing hemodialysis

Non-small-cell lung cancer(NSCLC)causes significant mortality worldwide.Patients with chronic renal failure have an increased risk of developing lungcancer.NSCLC Patients with chronic renal failure undergoing hemodialysis(HD)often exhibit poor performance,and chemotherapy is generally contraindicated.Oral epidermal growth factor receptor(EGFR)-tyrosine kinase inhibitors(TKIs)are effective treatment agents for NSCLC patients.However,the benefits andadverse effects of EGFR-TKIs in NSCLC undergoing HD are known.There are noclinical studies on the effects of EGFR-TKIs on NSCLC patients undergoing HD.We reviewed all previous case reports about EGFR-TKIs in NSCLC patientsundergoing HD.It is difficult to design studies about the effects of EGFR-TKIs inpatients undergoing HD,and this review is quite important.EGFR-TKIs are welltolerated in patients undergoing HD.The main routes of elimination of EGFRTKIsare metabolism via the liver,and renal elimination is minor.Therecommended doses and pharmacokinetics of these EGFR-TKIs for patientsundergoing HD are similar to those for patients with normal renal function.Theplasma protein binding of EGFR-TKIs is very high,and it is not necessary toadjust the dose after HD.In conclusion,EGFR-TKIs are effective and welltolerated in patients undergoing HD.

Sorafenib Acts through VEGFR-2 Inhibition in a Metastatic Clear-Cell Sarcoma of the Kidney

We report here the case of a young patient with metastatic clear-cell sarcoma of the kidney resistant to standard chemotherapy, and with complete response under sorafenib treatment. The remarkable response of her tumor to sorafenib led us to study sorafenib molecular targets in the metastatic tissue. Background: Biomarkers predicting response to anti-angiogenic tyrosine kinase inhibitors remain to be identified. Methods and Findings: In this paper, we studied the molecular targets of sorafenib in the lung metastasis of a kidney clear-cell sarcoma. In a patient with complete response under sorafenib treatment, we showed high VEGFR2 expression by tumor endothelial cells from the lung metastasis. Conclusion: The original mechanistic results that we obtained using immunostainings and quantitative RT-PCR on laser-microdissected tumor endothelial cells have a direct application in daily clinical practice: metastatic tumors with a large angiogenic component should be tested for VEGFRs expression to consider anti-angiogenic tyrosine kinase inhibitor treatments.

Development of a competitive enzyme-linked immunosorbent assay for therapeutic drug monitoring of afatinib

Afatinib is an oral tyrosine kinase inhibitor(TKI) approved for treating advanced non-small cell lung cancer. It is necessary to develop a simple quantification method for TKIs in order to facilitate therapeutic drug monitoring(TDM) in clinical settings. This study sought to develop a simple and sensitive competitive enzyme-linked immunosorbent assay(ELISA) to quantify afatinib in plasma for routine pharmacokinetic applications. An anti-afatinib antibody was obtained using(S)-N-4-(3-chloro-4-fluorophenyl)-7-(tetrahydrofuran-3-yloxy)-quinazoline-4,6-diamine(CTQD), which has the same substructure as afatinib, as a hapten. Enzyme labeling of afatinib with horseradish peroxidase was similarly performed using CTQD. A simple competitive ELISA for afatinib was developed based on the principle of direct competition between afatinib and the enzyme marker for the anti-afatinib antibody, which had been immobilized on the plastic surface of a microtiter plate. Plasma afatinib concentrations below the limit of quantification of 30 pg/mL were reproducibly measurable. Also, the values of plasma afatinib levels measured from 20 patients were comparable with those measured by high-performance liquid chromatography, and there was a strong correlation between the values determined by both methods(Y=0.976 X – 0.207, r=0.975). As indicated by its specificity and sensitivity, this newly developed ELISA for afatinib is an important tool for TDM and studies of the pharmacokinetics of afatinib.

Pazopanib Induced Hand-Foot Syndrome in a Patient Previously Treated with Sunitinib: A Possible Cumulative Skin Toxicity?

Hand-foot syndrome (HFS), also known as palmar-plantar erythrodysesthesia, is a skin toxicity that could be observed during target therapies such as with tyrosine-kinase inhibitors (TKI). It usually develops within the first 2 - 4 weeks of drug administration. We present a case of HFS induced by Pazopanib after 2 months of treatment, in patients previously treated with Sunitinib, suggesting a possible cumulative toxicity of two drugs. The clinical and therapeutic management of skin adverse reactions during TKI therapy usually requires 25% dose reduction and adequate local treatment. It is important for the clinicians to recognize clinical signs and symptoms of such skin toxicities. Attention should be paid especially when two or more drugs from the same class are used in combined treatment.

Risk of hepatitis B virus reactivation in cancer patients undergoing treatment with tyrosine kinase-inhibitors

This editorial commented on an article in the World Journal of Gastroenterology titled“Risks of Reactivation of Hepatitis B Virus in Oncological Patients Using Tyrosine Kinase-Inhibitors:Case Report and Literature Analysis”by Colapietro et al.In this editorial,we focused on providing a more comprehensive exploration of hepatitis B virus reactivation(HBVr)associated with the usage of tyrosine kinase inhibitors(TKIs).It includes insights into the mechanisms underlying HBV reactivation,the temporal relationship between TKIs and HBV reactivation,and preventive measures.The aim is to understand the need for nucleos(t)ide analogs(NAT)and serial blood tests for early recognition of reactivation and acute liver injury,along with management strategies.TKIs are considered to be an intermediate(1%-10%)of HBVr.Current guidelines stipulate that patients receiving therapy with high or moderate risks of reactivation or recent cancer diagnosis must have at least tested hepatitis B surface antigen,anti-hepatitis B core antigen(HBc),and anti-hepatitis B surface antibody.Anti-HBc screening in highly endemic areas means people with negative tests should be vaccinated against HBV.Nucleoside or nucleotide analogs(NAs)like entecavir(ETV),tenofovir disoproxil fumarate(TDF),and tenofovir alafenamide(TAF)form the basis of HBV reactivation prophylaxis and treatment during immunosuppression.Conversely,lamivudine,telbivudine,and adefovir are generally discouraged due to their reduced antiviral efficacy and higher risk of fostering drug-resistant viral strains.However,these less effective NAs may still be utilized in cases where ETV,TDF,and TAF are not feasible treatment options.

Somatic pharmacogenomics of gastrointestinal stromal tumor

Gastrointestinal stromal tumors(GISTs)are rare entities,which,however,represent the most common mesenchymal tumor of the gastrointestinal tract.The discovery of gain of function mutations on KIT and PDGFRA receptor genes led to a deep revolution in the knowledge of this tumor.This paved the way to the introduction of imatinib and other tyrosine-kinase inhibitors(TKIs),which terrifically revolutionized the prognosis of GIST patients.Currently,it is well established that tumor mutational status is the main player in clinical outcome;however,with the research advances,it has been slowly understood that GIST landscape is more complex than expected and the TKIs available are not effective for all the GIST subtypes.For this reason,in the era of tailored/personalized medicine,each GIST patient should be considered individually and genetic consult should be the first step to take in consideration in the therapeutic decision making process.