FDA Approval Summary: Vemurafenib for the Treatment of Patients with Erdheim-Chester Disease with the BRAFV600 Mutation.

On November 6, 2017, the U.S. Food and Drug Administration (FDA) granted regular approval to vemurafenib for the treatment of adult patients with Erdheim-Chester disease (ECD) with BRAFV600 mutation. ECD is a type of histiocytosis, a rare disorder characterized by an abnormal accumulation and behavior of cells of the mononuclear phagocytic system, which includes antigen-processing cells, dendritic cells, monocytes, or macrophages. Recently published data confirm a frequency of 54% of BRAFV600E mutations in patients with ECD.Approval was based on a cohort of 22 patients who received 960 mg of vemurafenib twice daily within the VE Basket Trial (MO28072), a single-arm, multicenter, multiple cohort study. Patients in the ECD cohort had histologically confirmed ECD with BRAFV600 mutations that were refractory to standard therapy. The ECD cohort achieved an overall response rate of 54.5% (95% confidence interval: 32.2-75.6), with a complete response rate of 4.5%. With a median duration of follow-up of 26.6 months, the median duration of response has not been reached. The most frequently reported adverse reactions (>50%) in the ECD cohort were arthralgia, rash maculo-papular, alopecia, fatigue, electrocardiogram QT interval prolonged, and skin papilloma. The median treatment duration for ECD patients in this study was 14.2 months. This article describes the FDA review of the vemurafenib efficacy supplement for patients with ECD with BRAFV600 mutations. IMPLICATIONS FOR PRACTICE: Vemurafenib, an oral monotherapy targeting a mutation in BRAF, is the first U.S. Food and Drug Administration approval for the treatment of Erdheim-Chester disease (ECD). ECD is an extremely rare hematopoietic neoplasm that represents clonal proliferation of myeloid progenitor cells. ECD may involve bone and one or more organ systems, primarily affecting adults in their 5th and 7th decades of life, with a slight male predominance. This approval provides an effective and reasonably safe therapy for patients with a serious and life-threatening condition for which no approved therapy exists.

FDA Approval Summary: Midostaurin for the Treatment of Advanced Systemic Mastocytosis.

In April 2017, the U.S. Food and Drug Administration granted regular approval to midostaurin for the treatment of adult patients with aggressive systemic mastocytosis (ASM), systemic mastocytosis with associated hematological neoplasm (SM-AHN), or mast cell leukemia (MCL). Approval was based on results from CPKC412D2201, a single-arm trial of midostaurin (100 mg orally twice daily) in previously treated or untreated patients. For the patients with ASM and SM-AHN, efficacy was established on the basis of confirmed complete remission (CR) plus incomplete remission (ICR) by modified Valent criteria with six cycles of midostaurin. There were no CRs reported; ICR was achieved by 6 of 16 patients (38%; 95% confidence interval [CI]: 15%-65%) with ASM and by 9 of 57 patients (16%; 95% CI: 7%-28%) with SM-AHN. Within the follow-up period, the median duration of response was not reached for the patients with ASM (range, 12.1+ to 36.8+ months) or with SM-AHN (range, 6.6+ to 52.1+ months). For the patients with MCL, efficacy was established on the basis of confirmed CR using modified 2013 International Working Group-Myeloproliferative Neoplasms Research and Treatment-European Competence Network on Mastocytosis criteria. Of 21 patients with MCL, 1 (5%) achieved a CR. Of 142 patients with SM evaluated for safety, 56% had dose modifications for toxicity, and 21% discontinued treatment due to a toxicity. Over 50% reported nausea, vomiting, or diarrhea, and ≥30% reported edema, musculoskeletal pain, fatigue, abdominal pain, or upper respiratory tract infection. New or worsening grade ≥3 lymphopenia, anemia, thrombocytopenia, or neutropenia developed in ≥20%. Although midostaurin is an active drug for treatment of advanced SM, it is not clear that the optimal dose has been identified. IMPLICATIONS FOR PRACTICE: Midostaurin is the only U.S. Food and Drug Administration-approved therapy for patients with systemic mastocytosis with associated hematological neoplasm and mast cell leukemia and is the only therapy approved for patients with aggressive systemic mastocytosis regardless of KIT D816V mutation status. Based on response rate and duration, midostaurin has meaningful clinical activity in these rare, life-threatening diseases.

FDA Approval Summary: Tocilizumab for Treatment of Chimeric Antigen Receptor T Cell-Induced Severe or Life-Threatening Cytokine Release Syndrome.

On August 30, 2017, the U.S. Food and Drug Administration approved Actemra (tocilizumab, Genentech, Inc., South San Francisco, CA) for the treatment of severe or life-threatening chimeric antigen receptor (CAR) T cell-induced cytokine release syndrome (CRS) in adults and in pediatric patients 2 years of age and older. The approval was based on a retrospective analysis of data for patients who developed CRS after treatment with CTL019 and KTE-C19 on prospective clinical trials. Evaluable patients had been treated with intravenous tocilizumab 8 mg/kg (12 mg/kg for patients <30 kg) for severe or life-threatening CRS; only the first episode of CRS was included in the analysis. The efficacy population for the CTL019 cohort included 24 male and 21 female patients (total 45 patients) of median age 12 years. The median time from the start of CRS to the first dose of tocilizumab was 4 days (range, 0-18 days). Patients were considered responders if CRS resolved within 14 days of the first dose of tocilizumab, if no more than 2 doses of tocilizumab were needed, and if no drugs other than tocilizumab and corticosteroids were used for treatment. Thirty-one patients (69%; 95% confidence interval, 53%-82%) achieved a response as defined. In an independent cohort of 15 patients with KTE-C19-induced CRS, 53% responded. Further study is needed to determine the optimal dose of tocilizumab and to confirm the safety of its use for treatment of patients with CAR T cell-induced CRS. IMPLICATIONS FOR PRACTICE: Severe or life-threatening chimeric antigen receptor (CAR) T cell-induced cytokine release syndrome (CRS) requires urgent treatment to prevent fatal outcomes. In two independent cohorts, the majority of patients with severe or life-threatening CAR T cell-induced CRS responded to treatment with one or two doses of tocilizumab in addition to advanced supportive care. More research is needed to determine the optimal dose and schedule of tocilizumab for treatment of CAR T cell-induced CRS.

FDA Approval Summary: Daratumumab for Treatment of Multiple Myeloma After One Prior Therapy.

On November 21, 2016, the U.S. Food and Drug Administration granted regular approval to daratumumab in combination with lenalidomide and dexamethasone, or bortezomib and dexamethasone, for the treatment of patients with multiple myeloma who have received at least one prior therapy. Approval was based on two randomized, open-label trials in which daratumumab was added to these backbone therapies. The MMY3003 trial demonstrated substantial improvement in progression-free survival (PFS) when daratumumab was added to lenalidomide and dexamethasone compared with lenalidomide and dexamethasone alone. The estimated median PFS had not been reached in the daratumumab arm and was 18.4 months in the control arm (hazard ratio [HR] = 0.37; 95% confidence interval [CI]: 0.27-0.52; p < .0001), representing a 63% reduction in the risk of disease progression or death. Similar results were observed in the MMY3004 trial comparing the combination of daratumumab, bortezomib, and dexamethasone with bortezomib and dexamethasone. The estimated median PFS was not reached in the daratumumab arm and was 7.2 months in the control arm (HR = 0.39; 95% CI: 0.28-0.53; p < .0001), representing a 61% reduction in the risk of disease progression or death. The most frequently reported adverse reactions (greater than or equal to 20%) in MMY3003 were infusion reactions, diarrhea, nausea, fatigue, pyrexia, upper respiratory tract infection, muscle spasm, cough, and dyspnea. The most frequently reported adverse reactions (greater than or equal to 20%) in MMY3004 were infusion reactions, diarrhea, peripheral edema, upper respiratory tract infection, and peripheral sensory neuropathy. Neutropenia and thrombocytopenia have been added to the Warnings and Precautions of the drug label. IMPLICATIONS FOR PRACTICE: Daratumumab, the first monoclonal antibody targeted against CD38, received U.S. Food and Drug Administration accelerated approval in 2015 based on data from single-agent, single-arm trials that provided response rate information. Results of the MMY3003 and MMY3004 trials established that daratumumab can be combined synergistically with some of the most highly active agents used to treat multiple myeloma, leading to daratumumab's regular approval in 2016. Daratumumab added to lenalidomide and dexamethasone, or bortezomib and dexamethasone, provides a substantial improvement in progression-free survival in previously treated patients with multiple myeloma. These combinations will likely improve the survival outlook for patients with multiple myeloma.

Dosage Optimization: A Regulatory Perspective for Developing Oncology Drugs.

Optimized dosages provide a secure foundation for the development of well-tolerated and effective oncology drugs. Project Optimus, an initiative within the Oncology Center of Excellence, strives to reform the dosage optimization and dosage selection paradigm in oncology. This initiative stems from the availability of targeted drugs and from the demand for more tolerable dosages from patients, caregivers, and advocates. Reforming dosage optimization for oncology drugs requires a paradigm shift from the one employed for cytotoxic chemotherapy to one that understands and considers the unique attributes of targeted therapy, immunotherapy, and cellular therapy. Limited characterization of dosage during drug development may result in (1) patients not staying on a therapy long-term due to poor tolerability, (2) failure to establish positive benefit-risk in clinical trials for regulatory approval (3) withdrawal of drugs from the market (4) removal of indications of drugs from the market. Timely access to drugs is important for all patients with cancer, so it is vital to iteratively analyze all nonclinical and clinically relevant data at each stage of development and leverage quantitative approaches, innovative trial designs, and regulatory support to arrive at dosages with favorable benefit-risk. This review highlights the key challenges and opportunities to embracing this new paradigm and realizing the full potential of new oncology therapies.

Pediatric Cancer Drug Development: Leveraging Insights in Cancer Biology and the Evolving Regulatory Landscape to Address Challenges and Guide Further Progress.

The discovery and development of anticancer drugs for pediatric patients have historically languished when compared to both past and recent activity in drug development for adult patients, notably the dramatic spike of targeted and immune-oncology therapies. The reasons for this difference are multifactorial. Recent changes in the regulatory landscape surrounding pediatric cancer drug development and the understanding that some pediatric cancers are driven by genetic perturbations that also drive disparate adult cancers afford new opportunities. The unique cancer-initiating events and dependencies of many pediatric cancers, however, require additional pediatric-specific strategies. Research efforts to unravel the underlying biology of pediatric cancers, innovative clinical trial designs, model-informed drug development, extrapolation from adult data, addressing the unique considerations in pediatric patients, and use of pediatric appropriate formulations, should all be considered for efficient development and dosage optimization of anticancer drugs for pediatric patients.

FDA Approval Summary: Dabrafenib in Combination with Trametinib for BRAFV600E Mutation-Positive Low-Grade Glioma.

On March 16, 2023, the FDA approved dabrafenib in combination with trametinib (Tafinlar, Mekinist; Novartis Pharmaceuticals Corporation) for the treatment of pediatric patients with low-grade glioma (LGG) with a BRAFV600E mutation who require systemic therapy. FDA also approved oral formulations of both drugs suitable for patients who cannot swallow pills. This approval was based on the LGG cohort from study CDRB436G2201 (NCT02684058), a multicenter, open-label trial in which pediatric patients with LGG with a BRAFV600E mutation were randomly assigned 2:1 to dabrafenib plus trametinib (D+T) or carboplatin plus vincristine (C+V). The overall response rate (ORR) by independent review based on Response Assessment in Neuro-oncology LGG (2017) criteria was assessed in 110 patients randomly assigned to D+T (n = 73) or C+V (n = 37). ORR was 47% [95% confidence interval (CI), 35-59] in the D+T arm and 11% (95% CI, 3.0-25) in the C+V arm. Duration of response (DOR) was 23.7 months (95% CI, 14.5-NE) in the D+T arm and not estimable (95% CI, 6.6- NE) in the C+V arm. Progression-free survival (PFS) was 20.1 months (95% CI: 12.8, NE) and 7.4 months (95% CI, 3.6- 11.8) [HR, 0.31 (95% CI, 0.17-0.55); P < 0.001] in the D+T and C+V arms, respectively. The most common (>20%) adverse reactions were pyrexia, rash, headache, vomiting, musculoskeletal pain, fatigue, diarrhea, dry skin, nausea, hemorrhage, abdominal pain, and dermatitis acneiform. This represents the first FDA approval of a systemic therapy for the first-line treatment of pediatric patients with LGG with a BRAFV600E mutation.

Perspectives on drug development for the treatment of chronic myeloid leukemia in pregnant patients and patients who are breastfeeding.

Tyrosine kinase inhibitors (TKI) have improved the outcome and life expectancy of patients with chronic myeloid leukemia (CML). Patients are diagnosed with CML at younger ages, and patients treated for CML may become pregnant or choose to breastfeed. The information available to date on the safety of TKIs during pregnancy and lactation and the optimal management of these patients is largely anecdotal, based on personal or small-group experience, and heterogeneous. A panel of interested parties was convened by US Food and Drug Administration (FDA) to analyze the current data and discuss possible solutions. Possible solutions include prospective data collection, in clinical trials and in routine clinical practice, a more uniform and specific data collection, and greater coordination among involved entities. Since patients with cancer are living longer, frequently receiving therapies for extended periods of time (or for life), data on appropriate management of patients through different reproductive phases of life are needed. It is thus time to change our approach for how to study treatment of cancer (including CML) during pregnancy or breastfeeding to develop evidence-based guidelines for safe and effective patient care.

Approval summary: Cetuximab in combination with cisplatin or carboplatin and 5-fluorouracil for the first-line treatment of patients with recurrent locoregional or metastatic squamous cell head and neck cancer.

On November 7, 2011, the U.S. Food and Drug Administration approved cetuximab in combination with cisplatin or carboplatin and 5-fluorouracil for the first-line treatment of patients with recurrent locoregional or metastatic squamous cell head and neck cancer. Approval was based on a randomized study of 442 patients conducted outside the U.S. Cisplatin (100 mg/m2 intravenously) or carboplatin (area under the curve 5 intravenously) on day 1 with 5-fluorouracil (1,000 mg/m2/day continuous intravenous infusion days 1-4) were administered every 3 weeks. Cetuximab, 400 mg/m2 intravenously, was administered initially followed by cetuximab, 250 mg/m2 intravenously weekly. After completion of six planned treatment courses, cetuximab patients without progression continued cetuximab 250 mg/m2 weekly. The study used European Union (EU)-approved cetuximab rather than U.S.-approved cetuximab. U.S.-approved cetuximab provides approximately 28% higher exposure relative to EU-approved cetuximab in a pharmacokinetic comparability study in monkeys. Overall survival, the primary efficacy endpoint, was significantly improved in cetuximab-treated patients (hazard ratio [HR]: 0.80; 95% confidence interval [CI]: 0.64-0.98; p = .034, stratified log-rank test). Median survival times were 10.1 and 7.4 months, respectively. Progression-free survival (PFS) was also significantly improved in patients receiving cetuximab (HR: 0.57; 95% CI: 0.46-0.72; p < .0001). Median PFS times were 5.5 and 3.3 months, respectively. Response rates were 35.6% and 19.5% (odds ratio: 2.33; 95% CI: 1.50-3.60; p = .0001). Adverse reactions (≥25%) from cetuximab plus chemotherapy treatment included nausea, anemia, vomiting, neutropenia, rash, asthenia, diarrhea, and anorexia. Conjunctivitis occurred in 10% of cetuximab patients. Other adverse reactions, sometimes severe, included infusion reactions, hypomagnesemia, hypocalcemia, and hypokalemia.

Landscape and Regulatory Perspective on Oncology Drugs in Pregnancy.

Cancers affecting pregnant women include breast cancer, melanoma, thyroid cancer, cervical cancer, lymphomas, and leukemias. The medical management of cancer during pregnancy with molecularly targeted oncology drugs remains quite challenging, with knowledge gaps about the drugs' safety and efficacy due to exclusion of pregnant women from cancer clinical trials, discontinuation of individuals who become pregnant during clinical trials, and limited information on appropriate dosing of molecularly targeted oncology drugs during pregnancy. Physiological changes occur during pregnancy and may result in alterations in the absorption, distribution, metabolism, and excretion of drugs used in pregnant women. Physiologically based pharmacokinetic modeling that incorporates physiological changes induced by both the cancer disease state and pregnancy has the potential to inform dosing of molecularly targeted oncology drugs for pregnant women, improve our understanding of the pharmacokinetic changes associated with pregnancy in patients with cancer, facilitate the design of potential studies of molecularly targeted oncology drugs in pregnant women to support dosing recommendations, and provide model-informed pharmacokinetic data to support regulatory decision making.

Utility of Physiologically Based Pharmacokinetic Modeling to Investigate the Impact of Physiological Changes of Pregnancy and Cancer on Oncology Drug Pharmacokinetics.

BACKGROUND: The treatment of cancer during pregnancy remains challenging with knowledge gaps in drug dosage, safety, and efficacy due to the under-representation of this population in clinical trials. Our aim was to investigate physiological changes reported in both pregnancy and cancer populations into a PBPK modeling framework that allows for a more accurate estimation of PK changes in pregnant patients with cancer. METHODS: Paclitaxel and docetaxel were selected to validate a population model using clinical data from pregnant patients with cancer. The validated population model was subsequently used to predict the PK of acalabrutinib in pregnant patients with cancer. RESULTS: The Simcyp pregnancy population model reasonably predicted the PK of docetaxel in pregnant patients with cancer, while a modified model that included a 2.5-fold increase in CYP2C8 abundance, consistent with the increased expression during pregnancy, was needed to reasonably predict the PK of paclitaxel in pregnant patients with cancer. Changes in protein binding levels of patients with cancer had a minimal impact on the predicted clearance of paclitaxel and docetaxel. PBPK modeling predicted approximately 60% lower AUC and Cmax for acalabrutinib in pregnant versus non-pregnant patients with cancer. CONCLUSIONS: Our results suggest that PBPK modeling is a promising approach to investigate the effects of pregnancy and cancer on the PK of oncology drugs and potentially inform dosing for pregnant patients with cancer. Further evaluation and refinement of the population model are needed for pregnant patients with cancer with additional compounds and clinical PK data.

Transfusions increase with nationally driven reimbursement changes of erythropoiesis stimulating agents for chemotherapy-induced anemia.

BACKGROUND: The Centers for Medicare and Medicaid Services (CMS) issued a national coverage determination (NCD) in July 2007, which imposed restrictions on the reimbursement of ESAs for Medicare and Medicaid beneficiaries. Since a majority of our patients are Medicare or Medicaid beneficiaries, we changed our clinical practice regarding the use of erythropoiesis stimulating agents (ESAs) to coincide with the NCD's reimbursement restriction. OBJECTIVE: To evaluate the number of transfusions in patients diagnosed with chemotherapy-induced anemia (CIA) receiving ESAs before and after the clinical practice was changed at the University of Illinois Medical Center (UIMC). METHODS: The medical records of all adult patients diagnosed with a nonmyeloid malignancy and CIA who received an ESA between July 2006 and June 2008 at the UIMC were evaluated. The patients were divided into two groups: patients in receipt of ESAs BEFORE (group 1) and AFTER (group 2). The number of transfusions, the response rates to chemotherapy and ESAs therapy, and overall survival were compared. RESULTS: Medical records for 110 patients were reviewed. More transfusions were given to patients AFTER we implemented the change in clinical practice (BEFORE 18 transfusions vs. AFTER 52 transfusions, p = 0.004). More patients responded to ESA therapy AFTER we implemented the change (67% vs. 83%, p = NS). The treatment response to chemotherapy and overall survival were similar between the two groups. CONCLUSION: The primary goal of reducing the number of transfusions in patients with CIA by administering ESAs cannot be met when clinical practice coincides with the NCD.

FDA Oncology Center of Excellence Project Renewal: Engaging the Oncology Community to Update Product Labeling for Older Oncology Drugs.

The FDA conducts independent reviews of scientific data obtained with investigational drug products to ensure that they are safe and effective. As a result of this process, FDA-approved product labeling is generated that is considered one of the most trusted sources of information for use of an approved drug. But FDA approval is only the beginning of the life cycle of a new drug; the first oncology drugs now have more than 7 decades of clinical experience in the postmarketing setting. Due, in part, to lack of incentives, some companies may not seek inclusion of new data, other than new safety information, in FDA-approved product labeling. Ensuring that product labeling provides adequate directions for use is important for all drugs, including older therapies that may form the backbone of many standard combination regimens for pediatric and adult cancers. Project Renewal is an FDA Oncology Center of Excellence pilot program that leverages expertise from the clinical and scientific oncology communities to review published literature and generate a drug-specific product report summarizing data that may support updates to FDA-approved product labeling. This article provides a broad overview of Project Renewal's collaborative pilot process for identifying and assessing literature supporting potential labeling updates, while engaging the oncology community to increase awareness of FDA's evidentiary standards and deliberative processes used when considering the addition of new indications and dosing regimens to product labeling.

FDA Approval Summary: Selumetinib for Plexiform Neurofibroma.

On April 10, 2020, the FDA approved selumetinib (KOSELUGO, AstraZeneca) for the treatment of pediatric patients 2 years of age and older with neurofibromatosis type 1 who have symptomatic, inoperable plexiform neurofibromas. Approval was based on demonstration of a durable overall response rate per Response Evaluation in Neurofibromatosis and Schwannomatosis criteria and supported by observed clinical improvements in plexiform neurofibroma-related symptoms and functional impairments in 50 pediatric patients with inoperable plexiform neurofibromas in a single-arm, multicenter trial. The overall reponse rate per NCI investigator assessment was 66% (95% confidence interval, 51-79) with at least 12 months of follow-up. The median duration of response was not reached, and 82% of responding patients experienced duration of response ≥12 months. Clinical outcome assessment endpoints provided supportive efficacy data. Risks of selumetinib are consistent with MAPK (MEK) inhibitor class effects, including ocular, cardiac, musculoskeletal, gastrointestinal, and dermatologic toxicities. Safety was assessed across a pooled database of 74 pediatric patients with plexiform neurofibromas and supported by adult and pediatric selumetinib clinical trial data in cancer indications. The benefit-risk assessment for selumetinib in patients with inoperable plexiform neurofibromas was considered favorable.

Effects of oral clotrimazole troches on the pharmacokinetics of oral and intravenous midazolam.

AIMS: The aim of the study was to determine the effects of oral clotrimazole troches on the pharmacokinetics of oral and intravenous midazolam in the plasma. METHODS: We conducted a randomized, open-label, four-way crossover study in 10 healthy volunteers. Each volunteer received oral midazolam 2 mg or intravenous midazolam 0.025 mg kg(-1) with and without oral clotrimazole troches 10 mg taken three times daily for 5 days. Each study period was separated by 14 days. Serial blood samples were collected up to 24 h after oral midazolam and 6 h after intravenous midazolam. Plasma concentrations for midazolam and its metabolite 1-hydroxymidazolam were measured and fitted to a noncompartmental model to estimate the pharmacokinetic parameters. RESULTS: Ten healthy volunteers aged 21-26 years provided written informed consent and were enrolled into the study. Clotrimazole decreased the apparent oral clearance of midazolam from 57 +/- 13 l h(-1)[95% confidence interval 48, 66] to 36 +/- 9.8 l h(-1) (95% confidence interval 29, 43) (P= 0.003). These changes were accompanied by a decrease in the area under the concentration-time curve (mean difference 22 microg h(-1) l(-1), P= 0.001) and bioavailability (mean difference 0.21, P= NS). There were no significant differences in the systemic clearance of midazolam with or without clotrimazole troches. CONCLUSIONS: Oral clotrimazole troches decreased the apparent oral clearance of midazolam; no significant differences in the systemic clearance of midazolam were found.

Influence of cyclooxygenase-1 genotype on ex vivo aspirin response in patients at risk for stroke.

BACKGROUND: We sought to determine whether cyclooxygenase-1 (PTGS1) genotype is associated with the ability of aspirin to inhibit platelet aggregation in patients at risk for stroke. METHODS: Blood and urine samples were collected from 60 subjects, including 28 African Americans, who were taking aspirin for primary or secondary stroke prevention. Samples were analyzed for the PTGS1 A-707G, PTGS1 P17L, and glycoprotein IIIa (ITGB3)P1(A1/A2) genotypes, ex-vivo platelet aggregation, serum cholesterol, plasma salicylate levels, and urinary 11-dehydrothromboxane B(2) (11-dhTxB(2)) concentrations. The association between PTGS1 A-707G and P17L genotypes and aspirin response, as assessed by ex vivo studies and 11-dhTxB(2) concentrations, was evaluated by statistical testing and nonlinear mapping. RESULTS: Salicylate concentrations, ITGB3 genotype distribution and 11-dhTxB(2) concentrations were similar among PTGS1 genotype groups. More subjects with the PTGS1 17PP versus PL genotype had incomplete ex-vivo inhibition of platelet aggregation by aspirin (57 vs. 20%; p = 0.04). Fifty-nine percent of subjects homozygous for both the PTGS -707A and 17P alleles, but none with both the PTGS1 -707G and 17L alleles had incomplete inhibition with aspirin; p = 0.04. Similarly, nonlinear mapping showed a direct relationship between the PTGS1 17P allele and decreased aspirin response. When analyzed separately by ethnicity, the association with the P17L genotype and aspirin response persisted in African Americans, but not Caucasians. CONCLUSIONS: Our data suggest that the PTGS1 P17L genotype contributes to response to aspirin as assessed by ex-vivo platelet aggregation. Our data further suggest that the association between PTGS1 genotype and aspirin response might vary by ethnicity.

Evaluation of the Modified Diet in Renal Disease equation for calculation of carboplatin dose.

BACKGROUND: Serum creatinine (SCr)-based formulas are used to estimate glomerular filtration rate (GFR) when calculating a dosage for carboplatin using the Calvert equation, but these formulas often underestimate measured GFR. The Modified Diet in Renal Disease (MDRD) equation appears to be a more accurate estimate of GFR in patients with chronic kidney disease, but this equation has not been studied extensively in patients with cancer. OBJECTIVE: To determine the absolute difference between the dose of carboplatin administered (traditional SCr-based formulas used to estimate GFR) and the dose calculated using the MDRD equation to estimate GFR and compare the frequencies of thrombocytopenia, neutropenia, and dosage modifications between subjects in whom the difference in dose was 20% or more (divergent) or less than 20% (nondivergent). METHODS: A retrospective analysis was conducted using data from patients who received carboplatin. Inclusion criteria were receipt of at least 2 doses of carboplatin, either as monotherapy or combination therapy, and documentation of desired area under the concentration-time curve (AUC). Patients were excluded if the baseline values needed to estimate GFR using the MDRD equation were not available. The absolute difference between the dose of carboplatin administered and that calculated using the MDRD equation was determined and, from this comparison, the subjects were divided into 2 groups (divergent vs nondivergent). RESULTS: The medical records of 186 adults who received more than 2 doses of carboplatin were included in the analysis. The doses were divergent in 89 (48%) patients. The mean target AUC values were 5.3 mg/mL/min and 5.1 mg/mL/min in the divergent and nondivergent groups, respectively, and most patients received cytotoxic regimens with a relatively low risk of febrile neutropenia. The frequencies of neutropenia, thrombocytopenia, and dosage modifications were similar between the 2 groups. Use of the MDRD equation to calculate the carboplatin dosage did not appear to result in a change in the frequency of myelosuppression or the need for dose modifications compared with traditional SCr-based formulas. CONCLUSIONS: The traditional SCr-based formulas for the calculation of carboplatin dosage should be used to estimate carboplatin dose until more data become available regarding the use of the MDRD equation in this population.

The pharmacokinetics of codeine and its metabolites in Blacks with sickle cell disease.

PURPOSE: We conducted a prospective, open-label study in 54 adult subjects with sickle cell disease to determine the relationship between morphine concentrations, cytochrome P450 (CYP) 2D6 genotype, and clinical outcomes. METHODS: A blood sample was obtained for genotyping and serial blood samples were drawn to measure codeine and its metabolites in the plasma before and after oral codeine sulfate 30 mg. Codeine and its metabolites were measured by liquid chromatography-tandem mass spectrometry (LC-MS). CYP2D6 genetic testing included four single nucleotide polymorphisms (SNP) indicative of three variant alleles: *17 (1023T); *29 (1659A, 3183A); and *41 (2988A) alleles. RESULTS: Thirty subjects (group I) had a mean (standard deviation) maximal morphine concentration of 2.0 (1.0) ng/ml. Morphine was not measurable in the remaining 24 subjects (group II). Nine (30%) subjects in group I and 11 (46%) subjects in group II carried a variant *17, *29, or *41 allele (p = 0.23); one (3%) subject in group I and 5 (21%) subjects in group II were homozygous for *17 or *29 allele (p = 0.07). Emergency room visits (group I 1.5 +/- 1.8 vs. group II 2.1 +/- 4.3, p = NS) did not differ based on metabolic status, but more hospital admissions (0.9 +/- 1.4 vs. 2.2 +/- 4.1, p = 0.05) were documented in patients with no measurable morphine concentrations. CONCLUSIONS: We conclude that Blacks with sickle cell disease without measurable plasma morphine levels after a single dose of codeine were not more likely to be a carrier of a single variant allele commonly associated with reduced CYP2D6 metabolic capacity; however, homozygosity for a variant CYP2D6 allele may result in reduced metabolic capacity. Furthermore, it appears that subjects without measurable morphine concentrations were more likely to be admitted to the hospital for an acute pain crisis.

Regulation of cytochrome P450 2C9 expression in primary cultures of human hepatocytes.

Cytochrome P450 2C9 (CYP2C9) expression is regulated by multiple nuclear receptors including the constitutive androstane receptor (CAR) and pregnane X receptor (PXR). We compared coregulation of CYP2C9 with CYP2B6 and CYP3A4, prototypical target genes for human CAR and PXR using human hepatocyte cultures treated for three days with the PXR activators clotrimazole, rifampin, and ritonavir; the CAR/PXR activator phenobarbital (PB); and the CAR-selective agonists CITCO, (6-(4-chlorophenyl)imidazo[2,1-beta][1,3]thiazole-5-carbaldehyde-O-(3,4-dichlorobenzyl)oxime) and phenytoin. Clotrimazole, rifampin, ritonavir, phenytoin, and phenobarbital induced CYP2C9 consistent with previous findings for CYP3A4. We observed EC(50) values of 519 microM (phenobarbital), 11 microM (phenytoin), and 0.75 microM (rifampin), similar to those for CYP3A4 induction. Avasimibe, a potent PXR activator, produced nearly identical concentration-dependent CYP2C9 and CYP3A4 activity profiles and EC(50) values. In 17 donors, rifampin increased mean basal CYP2C9 activity from 59 +/- 43 to 143 +/- 68 pmol/mg protein/min; fold induction ranged from 1.4- to 6.4-fold. Enzyme activity and mRNA measurements after rifampin, CITCO and PB treatment demonstrated potency and efficacy consistent with CYP2C9 regulation being analogous to CYP3A4 rather than CYP2B6. We demonstrate that hepatic CYP2C9 is differentially regulated by agonists of CAR and PXR, and despite sharing common regulatory mechanisms with CYP3A4 and CYP2B6; this enzyme exhibits an induction profile more closely aligned with that of CYP3A4.

FDA Approval Summary: (Daunorubicin and Cytarabine) Liposome for Injection for the Treatment of Adults with High-Risk Acute Myeloid Leukemia.

On August 3, 2017, the FDA granted regular approval to Vyxeos (also known as CPX-351; Jazz Pharmaceuticals), a liposomal formulation of daunorubicin and cytarabine in a fixed combination, for the treatment of adults with newly diagnosed therapy-related acute myeloid leukemia (t-AML) or acute myeloid leukemia (AML) with myelodysplasia-related changes (AML-MRC). Approval was based on data from Study CLTR0310-301, a randomized, multicenter, open-label, active-controlled trial comparing Vyxeos with a standard combination of daunorubicin and cytarabine ("7+3") in 309 patients 60-75 years of age with newly diagnosed t-AML or AML-MRC. Because of elemental copper concerns with the Vyxeos formulation, patients with Wilson disease were excluded from the study. Vyxeos demonstrated an improvement in overall survival (HR 0.69; 95% confidence interval, 0.52-0.90; P = 0.005) with an estimated median overall survival of 9.6 months compared with 5.9 months for the "7+3" control arm. The toxicity profile of Vyxeos was similar to that seen with standard "7+3" with the exception of more prolonged neutropenia and thrombocytopenia on the Vyxeos arm. Because the pharmacology of Vyxeos differs from that of other formulations of daunorubicin and cytarabine, labeling includes a warning against interchanging formulations during treatment. This is the first FDA-approved treatment specifically for patients with t-AML or AML-MRC.