Biomedical subjects
Grant Williams
Publications and source records attributed to Grant Williams.
Parallels between U.K. and U.S. healthcare systems.
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Letrozole in the extended adjuvant treatment of postmenopausal women with history of early-stage breast cancer who have completed 5 years of adjuvant tamoxifen.
PURPOSE: To present the basis of the decision of the Food and Drug Administration to grant accelerated approval for letrozole for extended adjuvant treatment of early-stage breast cancer in postmenopausal women after completion of adjuvant tamoxifen. EXPERIMENTAL DESIGN: The Food and Drug Administration reviewed the data from the MA17 trial, a single, multinational, randomized, double-blind, and placebo-controlled trial, submitted by the applicant to support the proposed new indication. RESULTS: MA17 consisted of a core study and Lipid and Bone Mineral Density safety substudies. It enrolled 5,187 patients. In the core study, median treatment duration was 24 months and median follow-up duration was 27.4 months. Using a conventional definition of disease-free survival, 122 events on letrozole and 193 events on placebo were observed (hazard ratio, 0.62; 95% confidence interval, 0.49-0.78; P = 0.00003). Distant disease-free survival also improved with letrozole, 55 versus 92 events (hazard ratio, 0.61; 95% confidence interval, 0.44-0.84; P = 0.003). No statistically significant improvement in overall survival was observed. Hot flushes, arthralgia/arthritis, myalgia, and new diagnosis of osteoporosis were more common on letrozole. Frequency of fractures and cardiovascular ischemic events was not significantly different. A statistically significant mean decrease in bone mineral density in the hip occurred at 24 months on letrozole. CONCLUSIONS: Letrozole administration led to a statistically significant prolongation in disease-free survival. Fractures and cardiovascular events were similar to placebo; however, new diagnoses of osteoporosis were more frequent. Short duration of treatment and follow-up precluded assessment of long-term safety and efficacy. Thus, accelerated approval was granted instead of regular approval.
Assessment of the value of confirming responses in clinical trials in oncology.
The requirement for a second assessment to confirm initial tumour response is required by all response guidelines. Its rationale, however, is not clear. We have conducted this study to compare validity of response rate assessment determined with and without secondary confirmation. Using specified criteria, nine trials of one single cytotoxic drug including 416 patients were selected from a pharmaceutical database. Objective response rates were determined by a single determination and by two separate determinations. 81 responses (19.5%, [15.8-23.6%]) were scored by the confirmation method and 97 responses (23.3% [19.3-27.7%]) by the no-confirmation method. The Kappa (kappa) coefficient of 0.89 indicates good agreement between both methods. This is the first study that systematically compares response rates calculated with and without performing response confirmation. Results show good agreement between both methods. We suggest that assessing response without confirmation may be the preferred method. These results should be confirmed by additional studies in a variety of cancer settings.
Accelerated approval of oncology products: a decade of experience.
We review the regulatory history of the accelerated approval process and summarize the U.S. Food and Drug Administration experience with accelerated approvals in oncology. The accelerated approval regulations, promulgated in 1992, allow approval of drugs for serious or life-threatening diseases on the basis of a surrogate endpoint that is reasonably likely to predict clinical benefit, such as survival or symptom benefit, pending completion of studies designed to confirm clinical benefit, referred to as phase 4 commitments, which are required to be conducted with due diligence. From 1992 to 2004, 22 applications involving anticancer drugs or biologics were approved. Of these 22 applications, accelerated approval was granted to 15 on the basis of findings from studies without an active comparator (i.e., single-arm studies or studies comparing two dose levels) and to the remaining seven on the basis of one or more randomized studies. Of the 22 approved applications, six (i.e., applications for dexrazoxane, irinotecan, capecitabine, docetaxel, imatinib mesylate, and oxaliplatin) have had one or more indications converted to regular approval. This review reports information that was presented at an Oncologic Drugs Advisory Committee meeting held in March 2003; it also presents a discussion of accelerated approval study designs, the study populations evaluated in the accelerated approval and confirmatory settings, and the integration of accelerated approval into a comprehensive drug development plan.
Cancer drug development: for populations or for individuals?
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Approval summary for bortezomib for injection in the treatment of multiple myeloma.
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Assessing tumor-related signs and symptoms to support cancer drug approval.
Cancer causes premature death and significant, often devastating, symptoms. While prolongation of survival is an obvious end point for new cancer drug approval, the US Food and Drug Administration (FDA) has also utilized end points that evaluate patient symptoms. In this article we discuss the end points, evidence, and analyses supporting cancer drug approvals based on evaluations of tumor-related signs and symptoms. With advice from the Oncologic Drug Advisory Committee (ODAC) in the late 1970s and early 1980s, FDA determined that acceptable end points for cancer drug approval were survival or an improvement in the quality of a patient's life, e.g., an improvement in tumor-related symptoms. This article summarizes 15 FDA cancer drug approvals based on patient symptom assessments and/or physical signs (thought to represent symptomatic improvement) as the primary evidence of effectiveness. These include painful bone events (three cases), cosmetic improvement in Kaposi's sarcoma and cutaneous T-cell lymphoma (six cases), the consequences (decreased transfusions, etc.) of long-duration responses in leukemias and lymphomas (two cases), relief of pulmonary or esophageal obstruction (two cases), and one case each of symptom benefit in pancreatic cancer (also associated with survival benefit) and pulmonary symptom benefit in lung cancer. An instructive example of an individual patient benefit end point is discussed, though it did not lead to a drug approval (the cisplatin-epinephrine gel application). Improved trial designs and analysis plans may allow greater reliance on morbidity assessments to support future cancer drug approvals. Drug sponsors are encouraged to include symptom assessments in cancer clinical trials and to perform further research to improve symptom-assessment methods. The FDA routinely meets with sponsors at End of Phase 2 Meetings to discuss drug development plans and the design of phase 3 trials. We encourage sponsors to request special protocol assessments (SPA) after meeting with the FDA to get written confirmation of the adequacy of plans for assessing cancer morbidity and quality of life, including protocols, end points, statistical analysis plans, and draft case report forms.
Language and brain injury.
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Evolution of the polarization of the optical afterglow of the gamma-ray burst GRB030329.
The association of a supernova with GRB030329 strongly supports the 'collapsar' model of gamma-ray bursts, where a relativistic jet forms after the progenitor star collapses. Such jets cannot be spatially resolved because gamma-ray bursts lie at cosmological distances; their existence is instead inferred from 'breaks' in the light curves of the afterglows, and from the theoretical desire to reduce the estimated total energy of the burst by proposing that most of it comes out in narrow beams. Temporal evolution of the polarization of the afterglows may provide independent evidence for the jet structure of the relativistic outflow. Small-level polarization ( approximately 1-3 per cent) has been reported for a few bursts, but its temporal evolution has yet to be established. Here we report polarimetric observations of the afterglow of GRB030329. We establish the polarization light curve, detect sustained polarization at the per cent level, and find significant variability. The data imply that the afterglow magnetic field has a small coherence length and is mostly random, probably generated by turbulence, in contrast with the picture arising from the high polarization detected in the prompt gamma-rays from GRB021206 (ref. 18).
Fulvestrant in postmenopausal women with advanced breast cancer.
PURPOSE: Patients with hormone-sensitive breast cancer who have responded to tamoxifen (TAM) may receive additional benefit from a second endocrine agent after progression or relapse after TAM therapy. Fulvestrant (FVT; Faslodex; i.m. injection, ICI 182,780; AstraZeneca Pharmaceuticals, Wilmington, DE) was developed as a selective antagonist of estrogen. In postmenopausal women, FVT is reported to inhibit the proliferative effects of estrogen on sensitive tissues and has no apparent measurable estrogenic activity. In this report, we describe the data and analyses supporting marketing approval for FVT by the United States Food and Drug Administration (FDA). EXPERIMENTAL DESIGN: The FDA review of 16 clinical trials and 6 pharmacokinetic trials, as well as preclinical pharmacology and chemistry data, are described. The bases for marketing approval are summarized. RESULTS: Toxicology studies in the mouse, rat, and dog showed minimal toxicity except for antiestrogenic effects. Because of FVT aqueous insolubility, an i.m. formulation, given at monthly intervals, was selected for clinical studies. Pharmacokinetic studies demonstrated sustained concentrations with monthly injection. In in vitro studies FVT was extensively metabolized, primarily by hepatic cytochrome P450 3A4. Phase I studies showed minimal toxicity, and the maximal dose (250 mg) was limited by FVT solubility. In two Phase III trials, 851 patients were randomized to either 250 mg FVT i.m. monthly or to anastrozole (ANZ) 1 mg p.o. daily. Ninety-six percent of patients had received TAM previously for early (adjuvant treatment) or advanced breast cancer. Response rates (RR) were 17% for both FVT and ANZ study arms in the North American trial, and were 20% versus 15% for FVT versus ANZ, respectively, in the European trial. There were no observed differences between study arms with respect to time to progression or survival. The most common FVT adverse events reported as potentially treatment-related were injection site reactions and hot flashes. CONCLUSIONS: FVT was approved on April 25, 2002 by the FDA for the treatment of hormone receptor-positive metastatic breast cancer in postmenopausal women with disease progression after antiestrogen therapy. The recommended dose is 250 mg i.m. monthly as a single 5 ml injection or as two concurrent 2.5 ml injections into the buttocks. Approval was based on results of two randomized trials comparing response rates and time to progression of FVT- and ANZ-treated patients. Complete prescribing information is available on the FDA website.
End points and United States Food and Drug Administration approval of oncology drugs.
PURPOSE: To summarize the end points used by the United States Food and Drug Administration (FDA) to approve new cancer drug applications over the last 13 years. MATERIALS AND METHODS: The FDA granted marketing approval to 71 oncology drug applications between January 1, 1990, and November 1, 2002. The end points used as the approval basis for each application are presented, and the rationale for each end point is discussed. RESULTS: The FDA grants either regular marketing approval or accelerated marketing approval for oncology drug applications. Regular approval is based on end points that demonstrate that the drug provides a longer life, a better life, or a favorable effect on an established surrogate for a longer life or a better life. Accelerated approval (AA) is based on a surrogate end point that is less well established but that is reasonably likely to predict a longer or a better life. Tumor response was the approval basis in 26 of 57 regular approvals, supported by relief of tumor-specific symptoms in nine of these 26 regular approvals. Relief of tumor-specific symptoms provided critical support for approval in 13 of 57 regular approvals. Approval was based on tumor response in 12 of 14 AAs. CONCLUSION: End points other than survival were the approval basis for 68% (39 of 57) of oncology drug marketing applications granted regular approval and for all 14 applications granted accelerated approval from January 1, 1990, to November 1, 2002.
Approval summary for zoledronic acid for treatment of multiple myeloma and cancer bone metastases.
PURPOSE: This article summarizes data submitted to the United States Food and Drug Administration for marketing approval of zoledronic acid (Zol; Novartis Pharmaceuticals, East Hanover, NJ), a bisphosphonate drug for treating patients with bone metastases. EXPERIMENTAL DESIGN: We review the chemistry, toxicology, pharmacology, and clinical study results submitted to support the supplemental New Drug Application for Zol for treatment of patients with bone metastases. Four- and 8-mg Zol doses were selected for Phase III trials based on bone resorption markers and clinical efficacy parameters. Patients with bone metastases were randomized in three Phase III studies (prostate cancer, solid tumors, and multiple myeloma or breast cancer) to receive 4 or 8 mg of Zol or to a control arm. The control was a placebo in the prostate cancer study and the other solid tumor study and was 90 mg of pamidronate (Pam) in the study of breast cancer and multiple myeloma. Studies were amended twice because of renal toxicity, initially to increase Zol infusion time from 5 to 15 min and later to decrease the dose in the Zol 8-mg arm to 4 mg. The efficacy end point was skeletal-related events (SREs), a composite end point consisting of pathologic fracture, radiation therapy to bone, changes in antineoplastic therapy for bone pain (prostate cancer only), surgery to bone, or spinal cord compression. This end point was analyzed either as the proportion of patients with SRE or time to first SRE. The breast cancer and myeloma study used a noninferiority statistical analysis methods to determine efficacy. RESULTS: In prostate cancer, both the proportions analysis and time-to-SRE analysis showed significantly less bone morbidity on Zol (4 mg) than placebo, but no significant difference between Zol (8 mg) and placebo in either analysis. In the solid tumor study, the time to SRE analysis but not the proportions analysis showed significantly less skeletal morbidity on Zol (4 mg) than placebo, and Zol (8 mg) was significantly better than placebo in both analyses. The breast cancer and myeloma study demonstrated noninferiority of Zol compared with Pam, with Zol retaining at least 49.3% of the Pam treatment effect previously demonstrated in placebo-controlled trials. Zol was approved on February 22, 2002, by the United States Food and Drug Administration for the "treatment of patients with multiple myeloma and documented bone metastases from solid tumors, in conjunction with standard antineoplastic therapy. Prostate cancer should have progressed after treatment with at least one hormonal therapy." The recommended dose and schedule is 4 mg of Zol infused over 15 min every 3-4 weeks. Increased Zol doses and shorter infusions are not recommended because of potential renal toxicity.
Approval summary for imatinib mesylate capsules in the treatment of chronic myelogenous leukemia.
PURPOSE: Chronic myelogenous leukemia (CML) results from the breakpoint cluster region-Abl fusion gene product, a tyrosine kinase involved in cell division and apoptosis. Imatinib, an orally administered inhibitor of the breakpoint cluster region-Abl tyrosine kinase, is capable of blocking proliferation and inducing apoptosis in CML cell lines. In this report, we describe the preclinical profile of imatinib and the data submitted in the New Drug Application that led to its marketing approval. EXPERIMENTAL DESIGN: Chemistry manufacturing and controls, animal toxicology, and biopharmaceutical data are described. Results of Phase I and Phase II clinical studies in patients with CML in blast crisis (CML-BC), in accelerated phase (CML-AP), and in chronic phase disease-resistant or intolerant to IFN-alpha (CML-CP) are summarized. The basis for marketing approval and postmarketing commitments by the pharmaceutical company are discussed. RESULTS: Toxicology studies in the rat, dog, and monkey show the hematological, renal, and hepatobiliary toxicity of imatinib. Pharmacokinetic studies in patients with CML demonstrate 98% imatinib bioavailability. The elimination half-lives of the parent drug and the major active metabolite, CGP74588, from plasma are approximately 18 and 40 h, respectively. Approximately 81% of the drug is eliminated in 7 days, 68% in the feces and 13% in the urine. Cytochrome P-450 3A4 is the main enzyme responsible for imatinib metabolism. Phase I and II clinical studies were conducted. The Phase I study, in 83 CML patients, evaluated oral imatinib doses from 25 to 1000 mg/day. Dose-limiting toxicity was not observed. The three Phase II studies, in CML-CP, CML-AP, and CML-BC, enrolled 1027 patients. CML-CP patients received 400 mg/day imatinib, whereas CML-AP and CML-BC patients generally received 600 mg/day imatinib. Primary study endpoints were cytogenetic response rate (CML-CP) and hematological response rate (CML-AP and CML-BC). The cytogenetic response rate for CML-CP patients was 49%. The hematological response rate of CML-AP and CML-BC patients was 63 and 26%, respectively. The most common imatinib adverse events were nausea, vomiting, myalgia, edema, and diarrhea. Elevated liver enzymes and/or bilirubin were reported in 27 patients (2.6%). CONCLUSIONS: On May 10, 2001, imatinib mesylate (Gleevec, formerly known as STI-571 and Glivec), manufactured and distributed by Novartis Pharmaceuticals, East Hanover, NJ, was approved by the United States Food and Drug Administration for the treatment of CML in three clinical settings: CML-BC, CML-AP, and CML-CP. This report summarizes the Food and Drug Administration's review of the New Drug Application.