Absorption, Metabolism, Distribution, and Excretion of Letermovir.

BACKGROUND: Letermovir is approved for prophylaxis of cytomegalovirus infection and disease in cytomegalovirus-seropositive hematopoietic stem-cell transplant (HSCT) recipients. OBJECTIVE: HSCT recipients are required to take many drugs concomitantly. The pharmacokinetics, absorption, distribution, metabolism, and excretion of letermovir and its potential to inhibit metabolizing enzymes and transporters in vitro were investigated to inform on the potential for drug-drug interactions (DDIs). METHODS: A combination of in vitro and in vivo studies described the absorption, distribution, metabolism, and routes of elimination of letermovir, as well as the enzymes and transporters involved in these processes. The effect of letermovir to inhibit and induce metabolizing enzymes and transporters was evaluated in vitro and its victim and perpetrator DDI potentials were predicted by applying the regulatory guidance for DDI assessment. RESULTS: Letermovir was a substrate of CYP3A4/5 and UGT1A1/3 in vitro. Letermovir showed concentration- dependent uptake into organic anionic transporting polypeptide (OATP)1B1/3-transfected cells and was a substrate of P-glycoprotein (P-gp). In a human ADME study, letermovir was primarily recovered as unchanged drug and minor amounts of a direct glucuronide in feces. Based on the metabolic pathway profiling of letermovir, there were few oxidative metabolites in human matrix. Letermovir inhibited CYP2B6, CYP2C8, CYP3A, and UGT1A1 in vitro, and induced CYP3A4 and CYP2B6 in hepatocytes. Letermovir also inhibited OATP1B1/3, OATP2B1, OAT3, OCT2, BCRP, BSEP, and P-gp. CONCLUSION: The body of work presented in this manuscript informed on the potential for DDIs when letermovir is administered both intravenously and orally in HSCT recipients.

Assessment of Pharmacokinetic Interaction Between Letermovir and Fluconazole in Healthy Participants.

Letermovir is a prophylactic agent for cytomegalovirus infection and disease in adult cytomegalovirus-seropositive recipients of allogeneic hematopoietic stem cell transplant. As the antifungal agent fluconazole is administered frequently in transplant recipients, a drug-drug interaction study was conducted between oral letermovir and oral fluconazole. A phase 1 open-label, fixed-sequence study was performed in healthy females (N = 14, 19-55 years). In Period 1, a single dose of fluconazole 400 mg was administered. Following a 14-day washout, a single dose of letermovir 480 mg was administered (Period 2), and after a 7-day washout, single doses of fluconazole 400 mg and letermovir 480 mg were coadministered in Period 3. Pharmacokinetics and safety were evaluated. The pharmacokinetics of fluconazole and letermovir were not meaningfully changed following coadministration. Fluconazole geometric mean ratio (GMR; 90% confidence interval [CI]) with letermovir for area under the concentration-versus-time curve from time 0 to infinity (AUC0-∞ ) was 1.03 (0.99-1.08); maximum concentration (Cmax ) was 0.95 (0.92-0.99). Letermovir AUC0-∞ GMR (90%CI) was 1.11 (1.01-1.23), and Cmax was 1.06 (0.93-1.21) following coadministration with fluconazole. Coadministration of fluconazole and letermovir was generally well tolerated.

Pharmacokinetics and Bioequivalence Estimation of Two Formulations of Alfuzosin Extended-Release Tablets.

Alfuzosin is a medication approved by the US Food and Drug Administration to treat benign prostatic hyperplasia symptoms. Bioequivalence studies are demanded by regulatory authorities to evaluate the expected in vivo biological similarity of 2 formulations of a medication. The aim of this study is to assess the bioavailability of the generic (test) and branded (reference) formulations of 10-mg alfuzosin extended-release tablets after oral administration to healthy adults under fed conditions. The study used a comparative randomized, single-dose, 2-way crossover open-label study design. Thirty-three participants were recruited and completed the clinical assessment. The pharmacokinetic parameters maximum plasma concentration (Cmax ), area under the plasma concentration-time curve (AUC0-t ), AUC extrapolated to infinity (AUC0-∞ ), time to maximum concentration, and elimination half-life were estimated to prove bioequivalence. The confidence intervals for the log-transformed test/reference ratios for alfuzosin 110.7% (98.0-124.9) and 112.0% (101.9-123.1) for Cmax and AUC0-t respectively, which are within the allowed limits specified by the regulatory authorities (80-125% for Cmax and AUC0-t ). The test formulation can therefore be prescribed as an alternative to the reference for symptomatic treatment of benign prostatic hyperplasia.

Population exposure-safety analysis of cediranib for Phase I and II studies in patients with cancer.

AIMS: A multistudy analysis of cediranib, a potent, selective inhibitor of all three vascular endothelial growth factor receptors (VEGFR-1, -2 and -3), was conducted to establish population exposure-safety models for the relationship of cediranib exposure to the safety endpoints, diastolic and systolic blood pressure (DBP and SBP) and diarrhoea in cancer patients. These models were applied to predict safety outcomes for different cediranib dose regimens. METHODS: Models for hypertension and diarrhoea were constructed based on data from 10 Phase I and three Phase II studies comprising 631 cancer patients following cediranib once-daily oral dosing. Daily DBP and SBP were simultaneously characterized using indirect response models for predicted cediranib concentration-time courses, while daily diarrhoea events were modelled as ordered categorical variables with a proportional odds model with a Markov element for predicted average cediranib concentrations. RESULTS: For 20 mg cediranib once-daily oral administration, the mean increase in DBP and SBP was predicted to be 7 (95% CI 3-13) and 8 mmHg (95% CI 3-16), respectively, while the probability of mild diarrhoea, but not the severity, was predicted to increase over time. Severe diarrhoea was predicted to be resolved rapidly upon discontinuation of cediranib treatment. CONCLUSIONS: Maximum blood pressure increase was observed within the first few days of cediranib treatment, consistent with the pharmacokinetic profile of cediranib reaching steady state in about 5 days. The probability of diarrhoea increased with cediranib concentration but was far more dependent on the status of diarrhoea predicted on the previous day.

Caco-2 Permeability Studies and In Vitro hERG Liability Assessment of Tryptanthrin and Indolinone.

Tryptanthrin and (E,Z)-3-(4-hydroxy-3,5-dimethoxybenzylidene)indolinone (indolinone) were recently isolated from Isatis tinctoria as potent anti-inflammatory and antiallergic alkaloids, and shown to inhibit COX-2, 5-LOX catalyzed leukotriene synthesis, and mast cell degranulation at low µM to nM concentrations. To assess their suitability for oral administration, we screened the compounds in an in vitro intestinal permeability assay using human colonic adenocarcinoma cells. For exact quantification of the compounds, validated UPLC-MS/MS methods were used. Tryptanthrin displayed high permeability (apparent permeability coefficient > 32.0 × 10(-6) cm/s) across the cell monolayer. The efflux ratio below 2 (< 1.12) and unchanged apparent permeability coefficient values in the presence of the P-glycoprotein inhibitor verapamil (50 µM) indicated that tryptanthrin was not involved in P-glycoprotein interactions. For indolinone, a low recovery was found in the human colon adenocarcinoma cell assay. High-resolution mass spectrometry pointed to extensive phase II metabolism of indolinone (sulfation and glucuronidation). Possible cardiotoxic liability of the compounds was assessed in vitro by measurement of an inhibitory effect on human ether-a-go-go-related gene tail currents in stably transfected HEK 293 cells using the patch clamp technique. Low human ether-a-go-go-related gene inhibition was found for tryptanthrin (IC50 > 10 µM) and indolinone (IC50 of 24.96 µM). The analysis of compounds using various in silico methods confirmed favorable pharmacokinetic properties, as well as a slight inhibition of the human ether-a-go-go-related gene potassium channel at micromolar concentrations.

Assessment of the pharmacokinetic interaction between the novel DPP-4 inhibitor linagliptin and a sulfonylurea, glyburide, in healthy subjects.

The aim of this study was to investigate the effect of the dipeptidyl peptidase-4 inhibitor linagliptin on the pharmacokinetics of glyburide (a CYP2C9 and CYP3A4 substrate) and vice versa. This randomized, open-label, three-period, two-way crossover study examined the effects of co-administration of multiple oral doses of linagliptin (5 mg/day × 6 days) and single doses of glyburide (1.75 mg/day × 1 day) on the relative bioavailability of either compound in healthy subjects (n = 20, age 18-55 years). Coadministration of glyburide did not alter the steady-state pharmacokinetics of linagliptin. Geometric mean ratios (GMRs) [90% CI] for (linagliptin + glyburide)/linagliptin AUC(τ,ss) and C(max,ss) were 101.7% [97.7-105.8%] and 100.8% [89.0-114.3%], respectively. For glyburide, there was a slight reduction in exposure of ∼14% when coadministered with linagliptin (GMRs [90% CI] for (glyburide + linagliptin)/glyburide AUC(0-∞) and C(max) were 85.7% [79.8-92.1%] and 86.2% [79.6-93.3%], respectively). However, this was not seen as clinically relevant due to the absence of a reliable dose-response relationship and the known large pharmacokinetic interindividual variability of glyburide. These results further support the assumption that linagliptin is not a clinically relevant inhibitor of CYP2C9 or CYP3A4 in vivo. Coadministration of linagliptin and glyburide had no clinically relevant effect on the pharmacokinetics of linagliptin or glyburide. Both agents were well tolerated and can be administered together without the need for dosage adjustments.

Evaluation of [(18)F]gefitinib as a molecular imaging probe for the assessment of the epidermal growth factor receptor status in malignant tumors.

PURPOSE: Gefitinib, an inhibitor of the epidermal growth factor receptor-tyrosine kinase (EGFR-TK), has shown potent effects in a subset of patients carrying specific EGFR-TK mutations in advanced non-small-cell lung cancer. In this study, we asked whether PET with [(18)F]gefitinib may be used to study noninvasively the pharmacokinetics of gefitinib in vivo and to image the EGFR status of cancer cells. MATERIALS AND METHODS: Synthesis of [(18)F]gefitinib has been previously described. The biodistribution and metabolic stability of [(18)F]gefitinib was assessed in mice and vervet monkeys for up to 2 h post injection by both micropositron emission tomography (PET)/computed tomography (CT) scans and postmortem ex vivo tissue harvesting. Uptake levels of radiolabeled gefitinib in EGFR-expressing human cancer cell lines with various levels of EGFR expression or mutation status were evaluated both in vivo and in vitro. RESULTS: MicroPET/CT scans in two species demonstrated a rapid and predominantly hepatobiliary clearance of [(18)F]gefitinib in vivo. However, uptake levels of radiolabeled gefitinib, both in vivo and in vitro, did not correlate with EGFR expression levels or functional status. This unexpected observation was due to high nonspecific, nonsaturable cellular uptake of gefitinib. CONCLUSION: The biodistribution of the drug analogue [(18)F]gefitinib suggests that it may be used to assess noninvasively the pharmacokinetics of gefitinib in patients by PET imaging. This is of clinical relevance, as insufficient intratumoral drug concentrations are considered to be a factor for resistance to gefitinib therapy. However, the highly nonspecific cellular binding of [(18)F]gefitinib may preclude the use of this imaging probe for noninvasive assessment of EGFR receptor status in patients.

A Bayesian population PK-PD model of ispinesib-induced myelosuppression.

The goal of the present analysis is to fit a Bayesian population pharmacokinetic pharmacodynomic (PK-PD) model to characterize the relationship between the concentration of ispinesib and changes in absolute neutrophil counts (ANC). Ispinesib, a kinesin spindle protein (KSP) inhibitor, blocks assembly of a functional mitotic spindle, leading to G2/M arrest. A first time in human, phase I open-label, non-randomized, dose-escalating study evaluated ispinesib at doses ranging from 1 to 21 mg/m(2). PK-PD data were collected from 45 patients with solid tumors. The pharmacokinetics of ispinesib were well characterized by a two-compartment model. A semimechanistic model was fit to the ANC. The PK and PD data were successfully modelled simultaneously. This is the first presentation of simultaneously fitting a PK-PD model to ANC using Bayesian methods. Bayesian methods allow for the use of prior information for some system-related parameters. The model may be used to examine different schedules, doses, and infusion times.

Erlotinib: small-molecule targeted therapy in the treatment of non-small-cell lung cancer.

BACKGROUND: Erlotinib is an oral tyrosine kinase inhibitor, targeting the human epidermal receptor type 1/ epidermal growth factor receptor, recently approved by the US Food and Drug Administration (FDA) for the treatment of patients with locally advanced or metastatic non-small-cell lung cancer (NSCLC) after the failure of more than 1 or 2 previous chemotherapeutic regimens. OBJECTIVE: The purpose of this article is to summarize the development, pharmacology, pharmacokinetics, efficacy, and adverse effects of erlotinib. METHODS: A literature search was conducted with the MEDLINE and EMBASE (1999-2005) databases using the search terms non-small-cell lung cancer, erlotinib, and epidermal growth factor receptor inhibitor. Abstracts from the American Society of Clinical Oncology and documents submitted to the FDA also were reviewed. RESULTS: BR.21, a randomized, placebo-controlled, multinational Phase III trial demonstrated clinically and statistically improved overall survival in patients with advanced or metastatic NSCLC treated with erlotinib versus placebo as second-line therapy. The erlotinib group had a median survival of 6.7 months versus a median survival of 4.7 months in the placebo group (P < 0.001). The toxicity profile of erlotinib was moderately benign, with the most commonly documented adverse events requiring dose reductions including skin rash (12%) and diarrhea (5%). Interstitial lung disease and relative fatalities were reported infrequently (0.8%) in patients receiving erlotinib. Two randomized, placebo-controlled, multicenter Phase III trials conducted in patients with locally advanced and metastatic NSCLC showed no clinical benefit with first-line administration of erlotinib plus concurrent platinum-based chemotherapy. CONCLUSIONS: For patients with NSCLC in whom more than 1 or 2 previous chemotherapeutic regimens have failed, erlotinib is an effective therapy with significant overall survival benefits. The use of erlotinib as first-line therapy in combination with platinum-based chemotherapeutic regimens, however, has failed to demonstrate efficacy in the treatment of NSCLC.

Clinical assessment of drug-induced QT prolongation in association with heart rate changes.

BACKGROUND: The formulas for heart rate (HR) correction of QT interval have been shown to overcorrect or undercorrect this interval with changes in HR. A Holter-monitoring method avoiding the need for any correction formulas is proposed as a means to assess drug-induced QT interval changes. METHODS: A thorough QT study included 2 single doses of the alpha1-adrenergic receptor blocker alfuzosin, placebo, and a QT-positive control arm (moxifloxacin) in 48 healthy subjects. Bazett, Fridericia, population-specific (QTcN), and subject-specific (QTcNi) correction formulas were applied to 12-lead electrocardio-graphic recording data. QT1000 (QT at RR = 1000 ms), QT largest bin (at the largest sample size bin), and QT average (average QT of all RR bins) were obtained from Holter recordings by use of custom software to perform rate-independent QT analysis. RESULTS: The 3 Holter end points provided similar results, as follows: Moxifloxacin-induced QT prolongation was 7.0 ms (95% confidence interval [CI], 4.4-9.6 ms) for QT1000, 6.9 ms (95% CI, 4.8-9.1 ms) for QT largest bin, and 6.6 ms (95% CI, 4.6-8.6 ms) for QT average. At the therapeutic dose (10 mg), alfuzosin did not induce significant change in the QT. The 40-mg dose of alfuzosin increased HR by 3.7 beats/min and induced a small QT1000 increase of 2.9 ms (95% CI, 0.3-5.5 ms) (QTcN, +4.6 ms [95% CI, 2.1-7.0 ms]; QTcNi, +4.7 ms [95% CI, 2.2-7.1 ms]). Data corrected by "universal" correction formulas still showed rate dependency and yielded larger QTc change estimations. The Holter method was able to show the drug-induced changes in QT rate dependence. CONCLUSIONS: The direct Holter-based QT interval measurement method provides an alternative approach to measure rate-independent estimates of QT interval changes during treatment.

Gefitinib: new preparation. Non small-cell lung cancer: stricter assessment needed.

(1) Platinum-based chemotherapy is generally used to treat advanced-stage non small-cell lung cancer (stages III and IV), but has only a modest impact on survival. There is no reference treatment. (2) Gefitinib inhibits the tyrosine kinase activity of the receptor for EGF (epidermal growth factor), which is thought to be involved in tumour growth. It has a temporary licence in France and is used on a named-patient basis, but full marketing authorisation has already been granted in Japan, the United States, and elsewhere. (3) Two double-blind dose-finding studies compared two doses of oral gefitinib monotherapy (250 mg/day and 500 mg/day) in patients in whom at least two lines of chemotherapy had failed. The results were favourable, with a median survival of 6 months and a symptomatic improvement in some patients, but they are undermined by the absence of a placebo group and by major protocol violations. (4) Two double-blind trials, each in more than 1000 patients, showed that gefitinib does not increase the efficacy of first-line platinum combinations. (5) About 15% of patients receiving gefitinib monotherapy in clinical trials stopped taking the treatment because of adverse events. The most frequent were gastrointestinal (diarrhea, nausea, vomiting) and cutaneous (rash, acne, dry skin, pruritus). (6) Interstitial pneumonitis occurred in about 1% of patients, and was fatal in about one-third of cases. (7) Gefitinib is metabolised by the cytochrome P450 isoenzyme CYP3A4, so carries a potentially high risk of interactions. (8) In practice, more thorough assessment of gefitinib is needed to determine whether this new drug is beneficial for patients with non small-cell lung cancer. Marketing authorisation is not currently justified.

Gefitinib for advanced or metastatic non-small cell lung cancer.

Gefitinib is approved as monotherapy for the treatment of locally advanced or metastatic non-small cell lung cancer (NSCLC) in patients who have failed prior platinum-based treatment and docetaxel chemotherapy. Its efficacy when compared to standard treatment and best supportive care is unproven. Common drug-related adverse effects include gastrointestinal and skin disorders. Rare but serious drug-related adverse events, such as shock, thrombophlebitis, thrombocytopenia and interstitial lung disease, have been reported.

Gefitinib therapy for advanced non-small-cell lung cancer.

OBJECTIVE: To review the pharmacology, pharmacokinetics, clinical efficacy, and toxicity of gefitinib in non-small-cell lung cancer (NSCLC). DATA SOURCES: Primary literature search through MEDLINE and CANCERLIT, and abstract presentations (1966-May 2003). STUDY SELECTION AND DATA EXTRACTION: All published trials and abstracts citing gefitinib were evaluated, and all information deemed relevant was included in this article. DATA SYNTHESIS: NSCLC is known to overexpress epidermal growth factor receptor (EGFR). Gefitinib is a selective EGFR tyrosine kinase inhibitor. Based on the Phase I/II trial results, the optimal dose is 250 mg/d orally. It is well tolerated, with minimal and reversible toxicity. Skin rash and diarrhea are the most common adverse effects. Recent trials have shown that gefitinib provided a 10% tumor response rate and improved disease-related symptoms in patients with refractory, advanced NSCLC. CONCLUSIONS: Gefitinib, with a unique mechanism of action and favorable toxicity profile, has demonstrated clinical activity in NSCLC patients with chemotherapy-refractory disease. It provides a valuable addition to the treatment options as monotherapy in patients with advanced NSCLC after failure of both platinum-based and docetaxel chemotherapies. Further research is required to evaluate the use of gefitinib in different clinical settings.

Erlotinib: CP 358774, NSC 718781, OSI 774, R 1415.

Erlotinib [Tarceva, R 1415, CP 358774, OSI 774, NSC 718781] is a small molecular, once-a-day, orally active inhibitor of the epidermal growth factor receptor tyrosine kinase. This profile has been selected from R&D Insight, a pharmaceutical intelligence database produced by Adis International Ltd. It is one of a class of anticancer drugs that target the underlying molecular mechanism involving oncogenes and tumour suppressor genes, which play critical roles in the conversion of normal cells into a cancerous state. Erlotinib is undergoing clinical development as an oral tablet by an alliance between OSI Pharmaceuticals, Genentech and Roche. OSI Pharmaceuticals, Genentech and Roche have entered an agreement for the global development and commercialisation of erlotinib. Under the terms of the agreement, Genentech and OSI will share costs and profit-taking for commercialising the product in the US. The overall costs of the development programme will be shared equally between the three companies. OSI will keep certain co-promotion rights in the US and Genentech will be responsible for commercialising the drug in the US should the FDA approve it. Roche will take the responsibility for obtaining regulatory approval and commercialisation in territories outside the US and pay royalties to OSI on net sales of the product in these markets. Initially, the alliance partners intend to pursue development of erlotinib in all the major tumour markets, particularly for non-small cell lung cancer (NSCLC) in which the group will focus on front-line combination approaches. Pfizer and OSI Pharmaceuticals in the US were developing erlotinib as a treatment for solid tumours. However, in June 2000, Pfizer merged with Warner-Lambert. The resulting company retained the Pfizer name, but in order to meet Federal Trade Commission requirements for the merger Pfizer granted all developmental and marketing rights for erlotinib to OSI Pharmaceuticals. This divestiture of the erlotinib portfolio, in effect, gave OSI a royalty-free, cashless license to the drug. In November 2001, OSI announced a partnership deal with HopeLink Corporation, a healthcare information technology company with an Internet-based Clinical Trial Service. The partnership will enable OSI to heighten awareness of its clinical trials and shorten patient accrual times. It will initially involve the presentation of the OSI phase III pancreatic and refractory NSCLC trials via Hopelink's Syndicated Network. In addition to this the two companies have also agreed to develop additional products and service together that will increase the efficiency of the clinical trial process, increase awareness of clinical trials, and enhance patient accrual techniques. OSI has also entered into an agreement with Therradex, a contract research organisation (CRO) to monitor phase II trials for erlotinib in NSCLC, ovarian and head and neck cancer. In addition, OSI entered into an agreement in 2001 with the US NCI. The NCI is conducting trials in a variety of different cancers. A phase III front-line NSCLC trial (TRIBUTE) of erlotinib in combination with carboplatin and paclitaxel was initiated in July 2001. The multicentre study is being conducted by Genentech in 1000 patients in the US, and will determine whether the addition of erlotinib to carboplatin chemotherapy is able to improve the duration of patient survival. Enrolment for this trial was completed in July 2002. An independent Data Monitoring Committee (DMC) has since reviewed the data from the trial and concluded that there are no safety or efficacy concerns that would warrant stopping the trial. However, the DMC did recommend stopping erlotinib at the time of disease progression or at the start of second-line therapy. A front-line phase III study of erlotinib in NSCLC (TALENT) in combination with gemcitabine and cisplatin chemotherapy was initiated by Roche in Europe in November 2001. Enrolment into this study was completed in September 2002, with approximately 1200 patients. Roche has confirmed that the study woulde has confirmed that the study would be included in the alliance's potential regulatory submission for front-line therapy in chemotherapy-naive patients in the US. Data from the trial is expected in the second half of 2003. OSI has opened two additional phase Ib studies to examine the potential of erlotinib in combination with carboplatin and paclitaxel in one study and gemcitabine and cisplatin in the other. A phase I study of erlotinib is also being conducted in patients with lung cancer in Japan. OSI received fast-track status from the US FDA in September 2002 for erlotinib as a second- or third-line treatment for patients with incurable stage IIIB/IV NSCLC who have failed to respond to standard therapy for advanced metastatic disease. Fast-track status was also granted to erlotinib in May 2002 for the treatment of chemotherapy-naive stage III/IV NSCLC. There are important differences between phase III studies of erlotinib and AstraZeneca's direct competitor drug gefitinib, which recently returned disappointing results in a frontline NSCLC trial with combination chemotherapy. In assessing the survival benefit of erlotinib with chemotherapy, the dose employed of 150 mg/day is the maximum tolerated dose (MTD), whereas the gefitinib trials were conducted at relatively lower doses than the MTD determined in earlier phase I studies. OSI is also investigating the survival benefit of erlotinib in a phase III study in refractory NSCLC patients, a key registration study. Patient size of the NSCLC trial was increased from 330 to 700 as OSI shifted emphasis from its pancreatic cancer trials. Phase II development for this indication was initiated based on data from a phase I trial, which had completed patient enrolment by April 2003. OSI and the US NCI signed a collaborative research agreement in 2001. The NCI is developing erlotinib through its CTEP programme for multiple tumour types including epithelial malignancies, gastrointestinal and genitourinary tracts, gynaecological malignancies and brain tumours. OSI supplies erlotinib for the trial, but the NCI provides the funding and manages the trials. A series of approximately ten phase Ib trials are already underway or were set to start in the US in 2001 to determine safety, tolerance and pharmacokinetic parameters of erlotinib in combination with a number of commonly used chemotherapeutic agents. The Wall Street Journal reported on 25 February 2002, that analysts at Robert Stephens, New York, USA, have forecast Tarceva to reach annual sales of >$US1 billion. Other analysts, at Merrill Lynch & Co., have predicted that products belonging to the same class as Tarceva could reach combined worldwide sales of $US6 billion to $US10 billion annually. In an earlier report by the Financial Times on 10 May 2001, it was stated that approximately 12 new anticancer agents are expected to be approved by the FDA through to the end of 2002. These agents, of which Tarceva is one, were said to have the potential to generate total sales of $US2.6 billion. Goldman Sachs have forecast Tarceva to reach peak sales of $US250 million for the indication of head and neck cancer alone. Previously in January 2001, the Financial Times claimed that OSI Pharmaceuticals, one of the development partners for Tarceva, stood to gain $US187 million pending regulatory approval. Genentech and Roche were each said to be buying $US35 million worth of OSI's stock and paying upfront fees. Tarceva is facing competition by two similar compounds, developed by AstraZeneca and ImClone, respectively.

Erlotinib OSI/Roche/Genentech.

Erlotinib (CP-358774, OSI-774, Tarceva), a quinazoline derivative, is an orally active epidermal growth factor receptor tyrosine kinase inhibitor under development jointly by Genentech, OSI (formerly Oncogene Science) and Roche, both as monotherapy and combination therapy for the potential treatment of solid tumors, including non-small-cell lung cancer (NSCLC) and pancreatic, breast, head and neck cancers [203487]. Development of the compound is most advanced for NSCLC and pancreatic cancer; in July 2001, phase III combination trials were initiated for NSCLC [416835]. In October 2001, phase III monotherapy trials in NSCLC and phase III combination trials in pancreatic cancer were also initiated [426704]. In Japan, the compound was in phase I studies in January 2002 [439189].

Anagrelide: a novel agent for the treatment of myeloproliferative disorders.

Anagrelide hydrochloride (Agrylin, Roberts Pharmaceutical Corp.) is an oral imidazoquinazoline agent that has been shown to reduce elevated platelet counts and the risk of thrombosis in patients with thrombocythaemia in various myeloproliferative disorders (MPD). It is currently approved by the FDA as oral treatment for essential thrombocythaemia (ET) and thrombocythaemia associated with polycythaemia vera (PV). Anagrelide selectively suppresses bone marrow megakaryocytes by interfering with the maturation process and decreasing platelet production without affecting the erythroid and myeloid progenitor cells. Other medications indicated for the treatment of thrombocythaemia, including interferon alpha (IFN-alpha), alkylating agents and hydroxyurea, suppress all cell lines. Anagrelide is known to inhibit platelet cyclic adenosine monophosphate (cAMP) phosphodiesterase at concentrations that exceed those achieved at doses used to treat ET. Anagrelide is extensively metabolised in the liver and its metabolites are primarily excreted in the urine. Adverse effects associated with the use of anagrelide are primarily caused by the drugs' direct vasodilating and positive inotropic effects. These include headache, hypotension and diarrhoea. It has also been known to cause fluid retention, tachycardia, nausea, abdominal pain and arrhythmias. The starting dose of anagrelide ranges from 0.5 mg q.i.d. to 1 mg b.i.d. with a maximum dose of 2.5 mg q.i.d. Adequate responses have been maintained with a median dose of 2-2.5 mg/day. Platelet counts begin to decrease in 7-10 days, however, they return to pre-treatment levels within 4-8 days if therapy is stopped. Anagrelide 2 mg/day for one year costs approximately US$6439, and treatment must continue indefinitely [1].

Anagrelide, a selective thrombocytopenic agent.

The pharmacology, pharmacokinetics, clinical efficacy, adverse effects, and dosage and administration of anagrelide are reviewed. Anagrelide is a selective thrombocytopenic agent with FDA-approved labeling for the treatment of essential thrombocythemia. Clinical trials have shown that the drug may have a role in the treatment of other chronic myeloproliferative disorders, including polycythemia vera, chronic myeloid leukemia, and agnogenic myeloid metaplasia. The mechanism by which anagrelide reduces platelet count is not yet clear. The current hypothesis is that anagrelide affects the late (postmitotic) phases of megakaryocyte development. Anagrelide has a large volume of distribution and is extensively metabolized; less than 1% is recovered unchanged in the urine. Plasma half-life after a 0.5-mg dose is 1.3 hours. Anagrelide's efficacy and safety have been evaluated in open-label, noncomparative trials, in which the response rate was 60-93%. Adverse effects include headache, diarrhea, edema, palpitations, and abdominal pain. Patients with renal or hepatic dysfunction need to be closely monitored for signs of toxicity. The recommended starting dosage is 0.5 mg four times a day or 1 mg twice a day, with dosage adjustment to the lowest effective amount required to reduce and maintain platelet count below 600 x 10(9)/L. The wholesale acquisition price for 0.5-mg capsules is $350 per 100. Whether anagrelide will replace hydroxyurea as first-line therapy in some or all patients remains to be determined. Anagrelide is effective in the treatment of essential thrombocythemia and may have a role in the treatment of other myeloproliferative disorders.