Developing an oncology portfolio of anticancer drugs: the experience of one pharmaceutical company.

For a company or institute that wishes to develop new anti-cancer agents, it is necessary to establish a portfolio of agents to reduce the risk of failure. Success rates for developing new agents are low and therefore different biological effect areas should be explored to ensure that at least one agent targeting cancer or a specific histological sub-type of cancer is effectively developed. This paper describes how one pharmaceutical company has developed a range of different agents with the ultimate aim of developing as many of these as is technically feasible into useful new medicines for the treatment of cancer.

Gefitinib ('Iressa', ZD1839) and new epidermal growth factor receptor inhibitors.

The epidermal growth factor receptor (EGFR) is a promising target for cancer therapy and a number of EGFR-targeted agents have been developed. Those most advanced in development are the EGFR tyrosine kinase inhibitors gefitinib ('Iressa', ZD1839) and erlotinib ('Tarceva', OSI-774), and the monoclonal antibody cetuximab ('Erbitux', IMC-C225). This review provides a clinical overview of these agents, highlighting their antitumour activities in different tumour types. Epidermal growth factor receptor-targeted agents are generally well tolerated and are not typically associated with the severe adverse events often seen with cytotoxic chemotherapy. Gefitinib is the agent with the most extensive clinical experience, particularly in non-small-cell lung cancer (NSCLC). Recently, gefitinib became the first-approved EGFR-targeted agent, for use in patients with previously treated advanced NSCLC in Japan, the USA and other countries. Further studies are required to explore the full potential of these novel agents either as monotherapy or combination therapy.

[Comparison of management of advanced cancer in various organs].

The management of advanced cancer presents the greatest challenge to physicians involved in oncology. There will usually be a large burden of disease; cure is unlikely; and the needs of the patient in terms of pain control and palliation will also be important over and above the direct treatment of the disease. Different issues will arise depending on the site and pathological type of the cancer. Increasingly over the past few years, treatment protocols and guidelines have been developed for different cancers, but these can only be rough guides rather than definite treatment recommendations. Additionally in most cancers advanced disease offers the opportunity for evaluation of new treatments in Phase II studies and other trials. With the new generation of molecular targeted therapies, such as EGFR inhibitors, striking results are being seen in advanced disease that compare favourably with what has been seen previously. Other agents such as those which attack the tumour vasculature may also have promise in this setting. Palliation is also an important aspect of the management of advanced disease, and pain control in particular is an important component of patient management. In summary, the treatment of advanced disease provides a test bed for new agents, but this need to develop better cancer therapies must be balanced against patient needs for a pain-free and comfortable end to life.

Growth factors and their receptors: new targets for prostate cancer therapy.

Stimulation of the signal transduction pathway of the epidermal growth-factor receptor (EGFR) tyrosine kinase family of receptors in tumor cells enhances cellular proliferation, prevents apoptosis, and promotes tumor-cell mobility, adhesion, and invasion. Therapeutic approaches used to target the EGFR and its signal transduction cascade include (1) monoclonal antibodies (eg, cetuximab [IMC-C225]) directed against the extracellular binding domain of the receptor; and (2) trastuzumab, a monoclonal antibody binding to the HER2 receptor; immunotoxin conjugates use an antibody directed against EGFR joined to a cell toxin. All are in clinical trials for a number of cancers, including prostate cancer. Antisense strategies are in preclinical development. Low-molecular-weight inhibitors of the EGFR tyrosine kinase also in clinical development include OSI-774, PD182905, PKI-166, CI-1033, and ZD1839. ZD1839 has shown encouraging results in patients with prostate cancer in phase 1 trials. mn

[Development of molecular targeting drugs for the treatment of cancer-therapeutic potential and issues to be addressed in global development].

A survey of cancer treatment in a sample of hospitals > 100 beds conducted in 1998 compared with experience in the US showed that good progress has been achieved in Japan in the screening and early treatment of gastric cancer, and that the prognosis for breast cancer is better than in the West. Although in the past, the cytotoxic therapies available to physicians in Japan vs the West have been different, recent acceleration of regulatory review will result in a convergence of treatment paradigms and some improvement in acute response in many tumour types. However, world wide there is a need for new improved therapies in all cancers evaluated. Particular needs are in the management of NSCLC, advanced disease and cancers which form micrometastases. The eventual hope is that cancer can be turned from a lethal disease into a chronic disease where patients maintain a good QOL. Apart from anti hormonal therapies, the usual approach has been to kill the cancerous cells. However, the new approaches to intervening in the growth and migration of cancerous cells or the host tissue response by molecular targeting offer the promise of achieving a step change in therapy. Although EGF tyrosine Kinase inhibitors such as ZD 1839 have been shown to cause a conventional tumour response in NSCLC, many of these new approaches are unlikely to show a short term response even if they have the capacity to affect tumour development and increase disease free survival. Some compounds will require combination therapy with a conventional cytotoxic or radiotherapy to show their full benefit. For conventional cytotoxics, the usual approach to development has been to select the maximum tolerated dose and then evaluate the efficacy in advanced disease. However, for the new approaches which will not have such severe dose limiting toxicities, it will be necessary to select a surrogate marker of the intended biological effect to select the optimal biological dose (OBD) and dose regimen in phase I/II studies for further evaluation in phase II or III studies which are designed to show the expected patient benefit. The tumour target, the stage of the disease and the possible need for concomitant therapy will also have to be considered according to the mechanism of action of the product.

Anti-EGF receptor therapy.

The epidermal growth factor receptor (EGFR) signalling pathway contributes to a number of processes important to tumour progression, including cell proliferation, apoptosis, angiogenesis and metastatic spread. EGFR signalling is thought to be an important cell survival mechanism in hormone-resistant prostate cancer. ZD1839 ('Iressa') is an orally active, selective EGFR-tyrosine kinase inhibitor (EGFR-TKI) which blocks signal transduction pathways implicated in promoting cancer growth. In preclinical studies, ZD1839 alone, and in combination with cytotoxic agents, produced reversible growth inhibition and growth delay in a wide range of tumour cell lines and human tumour xenografts. Preliminary results from phase I trials in patients with advanced disease suggest that ZD1839 has an acceptable tolerability profile and promising clinical efficacy in patients with a variety of tumour types, including hormone-resistant prostate cancer, where new treatment strategies are needed. Prostate Cancer and Prostatic Diseases (2000) 3, 296-302

A randomised comparison of 'Casodex' (bicalutamide) 150 mg monotherapy versus castration in the treatment of metastatic and locally advanced prostate cancer.

OBJECTIVES: To evaluate the efficacy and tolerability of 'Casodex' monotherapy (150 mg daily) for metastatic and locally advanced prostate cancer. METHODS: A total of 1,453 patients with either confirmed metastatic disease (M1), or T3/T4 non-metastatic disease with elevated prostate-specific antigen (M0) were recruited into one of two identical, multicentre, randomised studies to compare 'Casodex' 150 mg/day with castration. The protocols allowed for combined analysis. RESULTS: At a median follow-up period of approximately 100 weeks for both studies, 'Casodex' 150 mg was found to be less effective than castration in patients with metastatic disease (M1) at entry (hazard ratio of 1.30 for time to death) with a difference in median survival of 6 weeks. In symptomatic M1 patients, 'Casodex' was associated with a statistically significant improvement in subjective response (70%) compared with castration (58%). Analysis of a validated quality-of-life questionnaire proved an advantage for 'Casodex' in sexual interest and physical capacity. 'Casodex' had a substantially lower incidence of hot flushes compared to castration (6-13% compared with 39-44%) and the most commonly reported adverse events were those expected for a potent antiandrogen. However, in patients with M0 disease at entry, the data are still immature with only 13% of M0 patients having died. An initial analysis of this immature data has suggested that the results in these patients may be different to those obtained in patients with M1 disease. A further survival analysis in patients with M0 disease is therefore planned when the data are more mature. CONCLUSIONS: 'Casodex' 150 mg is less effective than castration in patients with M1 disease. However, 'Casodex' has shown a benefit in terms of quality of life and subjective response when compared to castration and has an acceptable tolerability profile. Thus 'Casodex' 150 mg monotherapy is an option for patients with M1 prostate cancer for whom surgical or medical castration is not indicated or is not acceptable.

New developments in cancer treatment with the novel thymidylate synthase inhibitor raltitrexed ('Tomudex').

Following the demonstration of efficacy, tolerability and quality-of-life benefits of raltitrexed ('Tomudex'), principally in advanced colorectal but also in other cancers, an extensive evaluation of combination therapy with other agents in patients with colorectal and other tumour types is being undertaken. This work has been prompted by preclinical observations of enhanced activity of raltitrexed when coadministered with other cytotoxic agents or radiotherapy and by preliminary results showing the activity of raltitrexed in patients with cancers other than colorectal. Raltitrexed is currently being investigated as monotherapy in phase I and II cancer studies, including head and neck cancer, hormone-resistant prostate cancer, paediatric and adult leukaemias and solid tumours, and soft tissue sarcoma. In addition, phase I clinical trials are evaluating the drug in combination with taxanes (paclitaxel) in solid tumours, anthracyclines (doxorubicin) in gastric carcinoma, topoisomerase I inhibitors (CPT-11) and 5-fluorouracil (both infusion and bolus regimens) in advanced colorectal cancer, platinum compounds (oxaliplatin and cisplatin) in a variety of tumours and radiotherapy in rectal cancer. Preliminary reports indicate good tolerability and acceptability of the combinations being investigated, with no dose-limiting toxicity being reported to date, and some early indications of efficacy.

Casodex (bicalutamide) 150-mg monotherapy compared with castration in patients with previously untreated nonmetastatic prostate cancer: results from two multicenter randomized trials at a median follow-up of 4 years.

OBJECTIVES: To compare the efficacy, tolerability, and quality of life benefits of bicalutamide (Casodex) 150-mg/day monotherapy and castration in previously untreated nonmetastatic (M0) advanced prostate cancer. METHODS: A total of 480 patients with Stage T3/T4 nonmetastatic disease randomly received oral bicalutamide 150 mg/day or castration (either bilateral orchiectomy or goserelin acetate [Zoladex] 3.6 mg every 28 days) in a 2:1 ratio in two open multicenter studies (studies 306 and 307). The design of these studies was similar to allow a pooled analysis. RESULTS: In the combined survival analysis, at median follow-up of 202 and 205 weeks in studies 306 and 307, respectively, with 31% of the cases resulting in death, bicalutamide 150-mg monotherapy was statistically equivalent to castration; the risk of death from any cause was 7% less with bicalutamide than with castration (hazard ratio [HR] = 0.93). Data on time to treatment failure and objective progression could not be pooled, as results for these end points differed between the trials. In study 306, bicalutamide 150-mg monotherapy increased time to objective progression (HR = 0.58; P = 0.033) and treatment failure (HR = 0.66; P = 0.074), whereas in study 307, time to progression (HR = 1.35; P = 0.0471) and treatment failure (HR = 1.24; P = 0.097) favored castration. Bicalutamide therapy showed significant advantages over castration for both sexual interest (P = 0.029) and physical capacity (P = 0.046). Bicalutamide 150-mg monotherapy was well tolerated. CONCLUSIONS: Bicalutamide 150-mg monotherapy provides a similar survival outcome to castration in previously untreated patients with nonmetastatic advanced prostate cancer and confers statistically significant benefits over castration with respect to sexual interest and physical capacity.

Bicalutamide (Casodex) in the treatment of prostate cancer: history of clinical development.

BACKGROUND: Bicalutamide (Casodex) is a new nonsteroidal antiandrogen developed for use in patients with prostate cancer. The efficacy and tolerability of bicalutamide as monotherapy and as combination therapy for patients with advanced prostate cancer have been evaluated in randomized clinical trials. Clinical trials are currently in progress to further evaluate bicalutamide as monotherapy in patients with advanced stages of disease and as adjuvant or first-line therapy in patients with early-stage disease. METHODS: A review of published trials of bicalutamide focusing on dose-ranging investigations, phase II and phase III monotherapy trials, a phase III trial of combined androgen blockade, and a safety overview. RESULTS: In dose-ranging trials, bicalutamide doses of 10-200 elicited biochemical, objective, and subjective responses; higher bicalutamide doses (up to 600 mg) have also been evaluated. A 50-mg daily dose of bicalutamide was initially evaluated as monotherapy in phase II and phase III trials; in subsequent trials, a 150-mg daily dose was investigated. A 150-mg daily dose is considered to provide equivalent survival outcome compared with castration in patients with locally advanced prostate cancer, whereas the benefits of a better quality of life and better palliation with the 150-mg daily bicalutamide dose relative to castration in patients with metastatic disease needs to be balanced against the small shortfall (median difference, 42 days) in survival. In combination with a luteinizing hormone-releasing hormone agonist analogue (LHRH-A), a 50-mg daily dose of bicalutamide has equivalent efficacy to a corresponding flutamide (250 mg three times daily) combination regimen. Treatment with the bicalutamide combination regimen resulted in a longer median survival than with the flutamide combination regimen. Bicalutamide is well tolerated when used as monotherapy or in combination with a LHRH-A. The benefits of bicalutamide as monotherapy include retention of libido and sexual potency and as combination therapy a lower incidence of diarrhea relative to flutamide. CONCLUSIONS: A 50-mg daily dose of bicalutamide is sufficient when given in combination with an agent, such as a LHRH-A, that lowers serum testosterone, but higher doses of bicalutamide may be needed when the drug is given as monotherapy. Bicalutamide, 50-mg daily, is a logical first choice for antiandrogen therapy when used in combination with an LHRH-A for the treatment of patients with advanced prostate cancer. Bicalutamide 150-mg daily is considered an effective monotherapy for use in patients with locally advanced disease. Additional clinical trials are currently in progress to further evaluate bicalutamide as a monotherapy for advanced prostate cancer and to assess its value as adjuvant or first-line therapy for early-stage prostate cancer.

Receptor affinity and potency of non-steroidal antiandrogens: translation of preclinical findings into clinical activity.

The non-steroidal antiandrogens flutamide (Eulexin((R))), nilutamide (Anandron((R))) and bicalutamide (Casodex((R))) are widely used in the treatment of advanced prostate cancer, particularly in combination with castration. The naturally occurring ligand 5alpha-DHT has higher binding affinity at the androgen receptor than the non-steroidal antiandrogens. Bicalutamide has an affinity two to four times higher than 2-hydroxyflutamide, the active metabolite of flutamide, and around two times higher than nilutamide for wild-type rat and human prostate androgen receptors. Animal studies have indicated that bicalutamide also exhibits greater potency in reducing seminal vesicle and ventral prostate weights and inhibiting prostate tumour growth than flutamide. Although preclinical data can give an indication of the likely clinical activity, clinical studies are required to determine effective, well-tolerated dosing regimens. As components of combined androgen blockade (CAB), controlled studies have shown survival benefits of flutamide plus a luteinising hormone-releasing hormone analogue (LHRH-A) over LHRH-A alone, and for nilutamide plus orchiectomy over orchiectomy alone. Other studies have failed to show such survival benefits, including those comparing flutamide plus orchiectomy with orchiectomy alone, and nilutamide plus LHRH-A with LHRH-A alone. In a direct comparative study, bicalutamide (50 mg, once daily) was compared with flutamide (250 mg, three times daily), each in combination with an LHRH-A. Both therapies were well tolerated, although more patients could not tolerate flutamide therapy: 25 flutamide plus LHRH-A and 2 bicalutamide plus LHRH-A patients withdrew from therapy due to diarrhoea. There were no statistically significant differences for time to progression or survival between the two antiandrogens. This clinical trial of bicalutamide confirms the prediction from preclinical studies that a 50 mg dose of bicalutamide would be appropriate for use in patients with advanced prostate cancer, and demonstrates that this bicalutamide dose is clinically effective when administered as part of CAB.

Casodex (bicalutamide): overview of a new antiandrogen developed for the treatment of prostate cancer.

Casodex (bicalutamide, Zeneca Ltd), has been developed for prostate cancer therapy. Its preclinical, pharmacokinetic, pharmacodynamic, clinical efficacy and tolerability data are described. Casodex is a potent and specific non-steroidal antiandrogen. Clinical studies indicated that Casodex is orally bioavailable and well absorbed, with a plasma half-life of around 1 week. A Casodex dose of 50 mg daily decreased prostatic acid phosphatase comparable with castration. This dose was, therefore, evaluated initially as monotherapy and later as a component of maximal androgen blockade. Using prostate specific antigen as an end point, Casodex 150 mg daily was well-tolerated with demonstrable evidence of activity. Casodex 150 mg monotherapy was less effective than castration in terms of efficacy in patients with metastatic disease at entry. However, in patients non-metastatic at entry, Casodex 150 mg monotherapy appeared to be equivalent to castration in terms of time to death (data immature). Casodex was well-tolerated. In combination treatment, Casodex at 50 mg daily was at least as effective as 750 mg flutamide (Eulexin, Schering-Plough International) with respect to time to treatment failure, equivalent in terms of survival, and better tolerated with respect to diarrhoea. In conclusion, Casodex is a good option for the antiandrogen component of maximal androgen blockade.

A randomised phase III cross-over study of tamoxifen versus megestrol acetate in advanced and recurrent breast cancer.

139 peri- and postmenopausal women with advanced or recurrent breast cancer who had not received prior hormonal therapy were randomised in an open, cross-over study comparing the synthetic progestogen megestrol acetate with tamoxifen. The response rate (CR/PR) to megestrol acetate (25%; 95% confidence interval (CI) 15-35%) was not significantly different from that produced by tamoxifen (33%, CI 22-44%). Time-to-treatment failure was also similar in the two groups. Cross-over treatment was given on progression in 76 cases. Cross-over response (CR/PR) was seen in 3 of 35 patients (9%) receiving megestrol acetate as second-line therapy and in 6 of 41 patients (15%) receiving tamoxifen second-line. There was no significant difference in survival between the groups (P = 0.17) with median survival times of 24 and 32 months for the megestrol acetate and tamoxifen groups, respectively. The toxicity profile of the two drugs was different, although significant toxicity was rare with either agent. Megestrol acetate is an effective treatment for advanced breast cancer in older women when used either as first- or second-line treatment. Cross-over response is seen following both treatments. Given that most patients now receive tamoxifen as adjuvant treatment, megestrol acetate would appear to be one of the logical choices for patients who find the side-effects of tamoxifen unacceptable and for those who relapse on tamoxifen with further hormone therapy being clinically indicated.

Bicalutamide: a new antiandrogen for use in combination with castration for patients with advanced prostate cancer.

Maximum androgen blockade, a relatively recent development in the treatment of prostate cancer, combines medical or surgical castration with antiandrogen therapy. A large randomized study comparing the non-steroidal antiandrogen, bicalutamide, with flutamide, each in combination with luteinizing hormone-releasing hormone (LHRH) analogs, showed that after a median follow-up of 49 weeks, the time to treatment failure was significantly longer for the bicalutamide patients compared with the flutamide patients (p = 0.005). After a median follow up to 95 weeks, bicalutamide in combination with LHRH analog therapy produced at least equivalent efficacy with flutamide in combination with LHRH analog therapy in terms of time to treatment failure and equivalent efficacy in terms of survival. The tolerability profile of bicalutamide, as based on reported findings and a literature review, indicates a superior tolerability to that of currently available antiandrogens, particularly with respect to diarrhea with a low incidence of treatment-related withdrawals.

Clinical progress with a new antiandrogen, Casodex (bicalutamide).

Casodex (bicalutamide, Zeneca Limited) is a nonsteroidal competitive inhibitor of androgens at the androgen receptor. The drug was developed to fulfil a number of needs for the treatment of prostate cancer. The specific aim was to demonstrate pharmacological activity, which would translate into clinical efficacy, good tolerability in the context of its use, oral availability, a convenient and forgiving dosing regimen, and clinical acceptability. Casodex has been shown to be orally bioavailable and well absorbed, with a plasma half-life of around 1 week. Although steady-state levels are not reached for 1 month, there is evidence that the androgen receptor blockade achieved with Casodex is equivalent to that of flutamide by the end of the first day. The dose of Casodex was established in a series of dose-ranging studies using the surrogate endpoints of prostatic acid phosphatase (PAP) and prostate-specific antigen (PSA). Initial studies suggested that a dose of 50 mg daily gave a fall in PAP equivalent to that seen with castration. This dose was, therefore, evaluated as monotherapy and subsequently as a component of combined androgen blockade. Higher doses were evaluated using PSA as a surrogate endpoint and, although doses up to 450 mg have been given to man, 150 mg daily is well tolerated with demonstrable evidence of activity. Although trials of the drug at 150 mg in monotherapy have, to date, not shown survival equivalence with castration, Casodex has been well tolerated with evidence of good symptomatic response and quality-of-life benefits including the potential of retaining libido. In combination treatment, Casodex is associated with significantly less gastrointestinal effects (diarrhoea) than the nonsteroidal antiandrogen flutamide (Eulexin, Schering-Plough International). Casodex is not associated with alcohol intolerance, pneumonitis and ocular defects which have been seen with the antiandrogen nilutamide (Anandron, Roussel). Moreover, since Casodex is a nonsteroidal antiandrogen, no steroidal effects have been seen.

High-dose bicalutamide monotherapy for the treatment of prostate cancer.

OBJECTIVES: Bicalutamide is a nonsteroidal competitive inhibitor of androgens at the androgen receptor. The level of blockade that can be achieved is dependent on the relative numbers of molecules of the agonist and the competitive antagonist around the receptor. Increasing the dose of a competitive inhibitor, therefore, should potentially increase the level of blockade. Bicalutamide has been investigated extensively at daily doses up to 150 mg, and there is evidence of increasing blockade at doses up to this point, as evidenced by increasing suppression of prostate-specific antigen (PSA) and also improvement in response rate, both subjective and objective. At doses of up to 150 mg, increases in plasma concentration of bicalutamide were approximately linear, and all doses were equally well tolerated. It was thought, therefore, that there was a case for investigating higher doses of bicalutamide to determine whether increased androgen blockade could be achieved with the use of bicalutamide as monotherapy. METHODS: A number of studies have now been carried out evaluating bicalutamide in daily doses of 200 mg, 300 mg, and 450 mg. The 200-mg dose has been evaluated as a primary treatment for advanced prostate cancer and also as a second-line treatment option for patients who have demonstrated a flutamide withdrawal response. RESULTS: In noncomparative trials, the decline in PSA value associated with daily doses of 200 mg bicalutamide was greater than that observed with daily doses of 150 mg, and there was also a slightly higher response rate. When 200 mg daily doses were used as therapy following failure of flutamide in combination with castration, and also following evidence of a flutamide withdrawal response, further responses were seen, perhaps suggesting the theory that in some prostate cancer cell mutations, bicalutamide acts as a pure antagonist rather than as a partial agonist. More recently, bicalutamide has been evaluated at higher doses: 20 patients have been exposed for periods up to 6 months at daily doses of 300 mg. This dose was well tolerated, and evidence of PSA suppression and responses were seen that were at least equivalent to those observed at lower doses. Pharmacokinetics evaluation has been carried out at this dose, and there is now evidence of nonlinearity of plasma concentrations, suggesting that further dose escalation is unlikely to confer major additional benefit over the 150- and 200-mg doses. To confirm the evidence of nonlinearity of plasma concentrations at doses > 200 mg, a randomization between 450 mg bicalutamide and medical castration is currently being carried out. Patients are still being recruited into this trial, but there has been no evidence of any change in the tolerability profile of bicalutamide at any dose > 150 mg. CONCLUSIONS: In summary, bicalutamide has shown increasing evidence of activity as a competitive blocker of the androgen receptor at daily doses of up to 200 mg. At daily doses > 200 mg, there is evidence of nonlinearity of plasma concentrations, and therefore further benefit is unlikely to be seen as a result of further escalating the dose of bicalutamide.

Worldwide activity and safety of bicalutamide: a summary review.

OBJECTIVES: To evaluate bicalutamide as a therapy in nearly 3000 patients with advanced prostate cancer and to determine the dose-ranging, pharmacodynamic, and pharmacokinetic properties of bicalutamide. To evaluate bicalutamide as a monotherapy or in combination with luteinizing hormone-releasing hormone analogue (LHRH-A) therapy. RESULTS: Bicalutamide is a potent, nonsteroidal antiandrogen with a plasma half-life consistent with a once-daily schedule. Monotherapy trials with 50 mg of bicalutamide established its intrinsic activity, as demonstrated by subjective and objective responses and decreases in PSA concentrations. In comparison with castration, 50 mg of bicalutamide monotherapy was inferior with respect to survival. In a randomized, double-blind (for antiandrogen therapy) trial, with a median follow-up of 49 weeks, 50 mg of bicalutamide plus an LHRH-A was superior (P = 0.005) to flutamide plus an LHRH-A in delaying time-to-treatment failure and was better tolerated, as was evident from a significantly (P < 0.001) lower incidence of diarrhea and fewer withdrawals for adverse events among bicalutamide-treated patients. With longer follow-up and a 34% mortality, survival was equivalent between groups. Dose-related effects of bicalutamide on serum PSA concentrations were clearly demonstrated in the clinical trial program. With a total exposure of > 2800 patient-years, bicalutamide has been shown to be a well-tolerated therapy with a low incidence of treatment-related withdrawals. CONCLUSIONS: Bicalutamide is a new antiandrogen that offers the convenience of once-daily administration, demonstrated activity in prostate cancer, and an excellent safety profile. Because it is effective and offers better tolerability than flutamide, bicalutamide represents a valid first choice for antiandrogen therapy in combination with castration for the treatment of patients with advanced prostate cancer.

Multicentre cross-over study of aminoglutethimide and trilostane in advanced postmenopausal breast cancer.

Trilostane and aminoglutethimide, both given with a physiological replacement dose of hydrocortisone, were randomly allocated to 112 eligible patients with postmenopausal advanced breast cancer. Following treatment failure on either drug the patient continued with the other, if they were in a suitable clinical condition. Sixty-three patients initially received trilostane, of whom 33 subsequently received aminoglutethimide; 49 patients initially had aminoglutethimide and 14 of these then received trilostane. Both groups of patients were comparable in all respects. There was no difference in the response rate to either drug or in the average time to disease progression for the two drugs. Of the 47 patients who received both drugs, nine (19%) showed a response to both, indicating no cross-resistance. Side effects were seen to both drugs in approximately half the patients; these were mainly gastrointestinal symptoms with trilostane and rashes and drowsiness with aminoglutethimide. There was no evidence of cross-over patient susceptibility to side effects.

A prospective randomized trial to evaluate different oral dose regimens of medroxyprogesterone acetate in women with advanced breast cancer.

A prospective randomized study was conducted to try to answer two questions: is a loading dose of medroxyprogesterone acetate (1000 mg p.o. q.d.s. for 48 h) superior to conventional dosing; and does an oral maintenance dose of 1000 mg daily offer any advantage over 500 mg daily in women with advanced breast cancer who have failed to respond to, or have relapsed after, tamoxifen? Of 211 patients randomized, 207 were evaluable. There was no improvement in response rates, time to response, response duration or overall survival as a result of the loading dose. When comparing high and low maintenance doses, there was a significant difference in response rates (48% versus 32%; chi 2 = 10.09, df = 2, P = 0.006) and survival (66% versus 41% alive at 12 months; chi 2 = 9.06, df = 1, P = 0.003) in favour of the higher dose regimen, although there was no significant difference in the duration of response. There was no additional toxicity attributable to the loading dose regimen, but side effects were more frequent with the high dose maintenance schedule (141 of 201 adverse effects occurring in these two groups) although the incidence of severe toxicity was similar with both high dose and low dose treatments.