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Biomedical subjects

Stephen R D Johnston

Publications and source records attributed to Stephen R D Johnston.

At least 19 recordsLinked to original sources
PubMed2006

A phase II study of weekly docetaxel in patients with anthracycline pretreated metastatic breast cancer.

BACKGROUND: Docetaxel has significant activity in metastatic breast cancer and weekly schedules are associated with less myelosuppression than 3-weekly schedules. We evaluated the toxicity and the activity of weekly docetaxel in anthracycline-pretreated patients. PATIENTS AND METHODS: A total of 42 patients were studied. Treatment consisted of docetaxel 35 mg/m2 weekly as a 30-min infusion for 6 weeks followed by a 2-week rest, with dexamethasone 8 mg i.v. pre-medication and 4 mg orally 12-hourly for 48 h following treatment. RESULTS: The median age of the patients was 53 years (range 34-74). Twenty-six (62%) patients had received prior chemotherapy for advanced disease. Patients received a median 10 weeks of treatment (range 1-24). 11 had a partial response (ORR 26%; 95% CI 13-39%), five of whom had relapsed <12 months since the end of previous anthracycline-based chemotherapy. In addition six patients (14%) had stable disease for >16 weeks. Myelosuppression was rare with only 2 patients (5%) experiencing grade 3 neutropenia (no grade 4 neutropenia). Non-haematological grade III toxicities were as follows: fatigue 17%, neuropathy 0%, hyperlacrimation 5%, stomatitis 7%, diarrhoea 14%, and cutaneous toxicity 19%. Skin toxicity consisted of limb/palmar-plantar erythematous reactions, or fixed-plaque erythrodysaesthesia. CONCLUSIONS: Weekly docetaxel has moderate activity in women with anthracycline pre-treated breast cancer. Although the level of myelosuppression is lower than 3-weekly regimens, this weekly regimen cannot be recommended due to the significant non-haematological toxicities associated with the treatment.

Adult↗
PubMed2006

Clinical efforts to combine endocrine agents with targeted therapies against epidermal growth factor receptor/human epidermal growth factor receptor 2 and mammalian target of rapamycin in breast cancer.

Enhancing the benefit of endocrine therapy by overcoming de novo or acquired resistance remains an important goal in systemic breast cancer therapy. Progress continues to be made in elucidating the molecular pathways by which estrogen receptor-positive breast cancer cells escape from endocrine therapy. The increasing recognition of the roles of epidermal growth factor receptor (EGFR) and human EGFR2 in cross-talk activation of estrogen receptor signaling has led to studies aimed at identifying whether small-molecule tyrosine kinase inhibitors targeted against these receptors give additive or synergistic effects when combined with endocrine agents. Activation of the phosphatidylinositol-3-OH kinase/Akt pathway has also been associated with resistance to either tamoxifen or estrogen deprivation, and preclinical studies have shown that the mammalian target of rapamycin antagonist temsirolimus can restore endocrine sensitivity in breast cancer cells. Randomized phase II trials of aromatase inhibitors combined with EGFR/human EGFR2 tyrosine kinase inhibitors or mammalian target of rapamycin antagonists have been completed in both the neoadjuvant and advanced breast cancer settings. Larger phase III trials with both approaches are now in progress and have been powered to detect whether either strategy can significantly prolong time to disease progression compared with endocrine therapy alone. The correlation of molecular and clinical results from these ongoing studies will be important to establish appropriate biological variables for selecting those patients who may benefit most from this combined approach.

Antineoplastic Agents, Hormonal↗
PubMed2006

Lapatinib: a novel EGFR/HER2 tyrosine kinase inhibitor for cancer.

Lapatinib is an oral dual tyrosine kinase inhibitor that targets epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor-2 (HER2), both frequently overexpressed in human cancer. Preclinical data have shown that lapatinib is a potent and selective inhibitor of the tyrosine kinase domain of EGFR and HER2, and tumor cells that overexpress these receptors are growth inhibited by lapatinib both in vitro and in vivo. Phase I clinical trials have shown that lapatinib is well tolerated, with mild diarrhea and rash the most frequent toxicities, and early evidence of clinical efficacy has been reported especially in HER2-positive breast cancer. Phase II studies have shown activity for lapatinib in trastuzumab-refractory breast cancer either alone or in combination with trastuzumab. When used as first-line monotherapy for advanced breast cancer, objective tumor responses have been seen in 28% of patients with untreated HER2-positive advanced breast cancer. An extensive phase III program in advanced breast cancer is now in progress both for refractory disease and as first-line therapy in combination with chemotherapy with and without trastuzumab, and with endocrine therapy. Phase II studies have also been conducted in a variety of other tumors, including renal cell cancer. Parallel biomarker studies are starting to elucidate predictive molecular phenotypes that may indicate likelihood of response to lapatinib, and these may direct future trials with this oral tyrosine kinase inhibitor.

Clinical Trials as Topic↗
PubMed2006

Cost effectiveness of extended adjuvant letrozole in postmenopausal women after adjuvant tamoxifen therapy: the UK perspective.

BACKGROUND: MA17 was a randomised placebo-controlled trial of letrozole 2.5 mg/day in 5187 estrogen receptor-positive, 50% node-negative, postmenopausal women (median age 62 years at enrollment) with early breast cancer, post-5 years' adjuvant tamoxifen therapy. The objective of this evaluation was to extrapolate the findings from the MA17 trial to estimate the lifetime cost effectiveness of letrozole in this setting. METHODS: A Markov model was used to estimate the incremental cost per QALY gained with extended adjuvant letrozole versus no therapy. Probabilities of disease progression and death were estimated using data from the MA17 study and other secondary sources. Costs of breast cancer care (letrozole therapy, surveillance, recurrences, terminal care) and treatment of osteoporosis and utilities were derived from literature. A full probabilistic sensitivity analysis was undertaken. The analysis was conducted from the perspective of the UK National Health Service (NHS) and cost estimates reflect 2004 values. All costs and outcomes were discounted at 3.5%. RESULTS: Extended adjuvant letrozole resulted in a gain of 0.36 QALYs per patient (13.66 vs 13.30 with no therapy). These benefits were obtained at an additional expected lifetime cost of 3732 pounds per patient (10,833 pounds letrozole vs 7101 pounds with no therapy). Cost effectiveness was estimated at 10,338 pounds per QALY gained (95% CI 5276, 43,828). The results were robust to sensitivity analyses. CONCLUSION: Five years of letrozole therapy appears to be cost effective from the NHS perspective and should be considered in women with early breast cancer, following tamoxifen adjuvant therapy.

Aged↗
PubMed2006

Cost-effectiveness of extended adjuvant letrozole therapy after 5 years of adjuvant tamoxifen therapy in postmenopausal women with early-stage breast cancer.

OBJECTIVE: To estimate the cost-effectiveness of extended adjuvant letrozole in postmenopausal women with early breast cancer and estrogen or progesterone receptor-positive tumors who had completed 5 years of adjuvant tamoxifen. STUDY DESIGN: Cost-effectiveness analysis using a Markov model. METHODS: Using a Markov model, we estimated the incremental cost per quality-adjusted life-year (QALY) gained with extended adjuvant letrozole vs no extended adjuvant therapy. Probabilities of breast cancer recurrence or new contralateral tumor adverse effects and death were estimated using data from the MA.17 study and other secondary sources. Costs (in 2004 US dollars) and quality-of-life effects (utilities) of breast cancer events and adverse effects were derived from the literature. RESULTS: In base-case analyses, extended adjuvant letrozole vs no extended adjuvant therapy results in an expected gain of 0.34 QALYs per patient (13.62 vs 13.28 QALYs), at an additional lifetime cost of 9699 dollars per patient (55,254 dollars vs 45,555 dollars). The incremental cost per QALY gained with letrozole is 28,728 dollars. Cost-effectiveness is sensitive to the assumed reduction in risk of breast cancer events with letrozole but is insensitive to the risks, costs, and quality-of-life effects of osteoporosis and hip fracture. Cost-effectiveness is less than 100,000 dollars per QALY for node-positive patients younger than 81 years and for node-negative patients younger than 73 years. CONCLUSION: For postmenopausal women with early breast cancer who have completed 5 years of adjuvant tamoxifen, the cost-effectiveness of extended adjuvant letrozole is within the range of other generally accepted medical interventions in the United States.

Adult↗
PubMed2005

Endocrinology and hormone therapy in breast cancer: selective oestrogen receptor modulators and downregulators for breast cancer - have they lost their way?

Although tamoxifen has been an effective treatment for breast cancer, several novel anti-oestrogen compounds have been developed with a reduced agonist profile on breast and gynaecological tissues. These include selective oestrogen receptor modulators (SERMs; both 'tamoxifen-like' and 'fixed-ring' SERMs) and selective oestrogen receptor downregulators (SERDs), although none has been proved superior in efficacy to tamoxifen in various advanced breast cancer trials. Thus, many have questioned whether a need for SERMs in breast cancer still exists, although chemoprevention remains a possible niche setting. In contrast, SERDs may have useful efficacy following aromatase inhibitors because of their unique mechanism of action, and clinical trials to determine their optimal use or sequence are ongoing.

Antineoplastic Agents, Hormonal↗
PubMed2005

Aromatase inhibitors: combinations with fulvestrant or signal transduction inhibitors as a strategy to overcome endocrine resistance.

There is an increasing rationale for effective combinations of endocrine therapy with novel drugs that target aberrant signal transduction pathways in estrogen receptor (ER) positive breast cancer. Prolonged endocrine therapy can be associated with an acquired increase in peptide growth factor signaling (EGFR, HER2), together with cross-talk activation of ER-dependent gene transcription and cell growth that leads to endocrine resistance. Current approaches to target these pathways include both the selective ER downregulator fulvestrant, and various signal transduction inhibitors (STIs). Fulvestrant can overcome resistance to tamoxifen (TAM-R) and long-term estrogen deprivation (LTED-R) in experimental models by reducing ER expression, and represents a current option for post-menopausal women with endocrine resistant ER+ve breast cancer. Emerging data suggest that fulvestrant's effect may be greater when combined with estrogen deprivation, and several phase III trials are assessing fulvestrant combined with aromatase inhibitors (AIs). Small molecule STIs such as tyrosine kinase inhibitors (TKIs), farnesyltransferase inhibitors (FTIs) and mTOR antagonists are also active in breast cancer. Pre-clinical data suggest that combined endocrine/STI therapy may result in greater growth inhibition than either therapy alone, and thus delay emergence of resistance. Several clinical trials are now examining STIs combined with AIs both in the tamoxifen-resistant and first-line advanced breast cancer setting, while pre-surgical studies are investigating the efficacy of combined endocrine/STI therapy utilising biological primary endpoints. This article reviews the pre-clinical rationale for this strategy and the clinical trials in this area.

Antineoplastic Agents, Hormonal↗
PubMed2005

Elevated ERK1/ERK2/estrogen receptor cross-talk enhances estrogen-mediated signaling during long-term estrogen deprivation.

The knowledge that steroids play a pivotal role in the development of breast cancer has been exploited clinically by the development of endocrine treatments. These have sought to perturb the steroid hormone environment of the tumour cells, predominately by withdrawal or antagonism of oestrogen. Unfortunately, the beneficial actions of existing endocrine treatments are attenuated by the ability of tumours to circumvent the need for steroid hormones, whilst in most cases, retaining the nuclear steroid receptors. The mechanisms involved in resistance to estrogen deprivation are of major clinical relevance for optimal treatment of breast cancer patients and the development of new therapeutic regimes. We have shown that long-term culture of MCF7 cells in medium depleted of oestrogen (LTED) results in hypersensitivity to oestradiol (E2) coinciding with elevated levels of both ERalpha phosphorylated on Ser(118) and ERK1/ERK2. Our data suggest elevated ERK1/ERK2 activity results wholly or in part from enhanced ERBB2 expression in the LTED cells. These cells showed greater sensitivity to the tyrosine kinase inhibitor ZD1839 in both ERalpha-mediated transcription and growth assays compared with the wt-MCF7. Similarly the MEK inhibitor U0126 decreased basal ERalpha-mediated transcription and proliferation in the LTED cells by 50% and reduced their sensitivity to the proliferative effects of E2 10-fold, whilst having no effect on the wild type (wt). However, complete suppression of ERK1/ERK2 activity in the LTED cells did not inhibit ERalpha Ser(118) phosphorylation suggesting that the cells remained ligand-dependent. This was further confirmed by the increased sensitivity of the LTED cells to the growth suppressive effects of ICI 182,780 and suggested that the LTED cells remained wholly or partially dependent on oestrogen receptor (ER)/oestrogen responsive elements directed growth. These findings suggest that treatments targeted at growth factor signalling pathways may be useful in patients acquiring resistance to oestrogen deprivation with aromatase inhibitors and that the pure anti-oestrogen ICI 182,780 may also be effective by blocking or destabilizing ER and hence disrupting cross-talk.

Breast Neoplasms↗
PubMed2005

Potential of endogenous estrogen receptor beta to influence the selective ER modulator ERbeta complex.

The ratio of estrogen receptor beta (ERbeta) to ERalpha can alter the estrogen-like properties of tamoxifen. Transient transfection of ERbeta cDNA into cells can decrease the estrogen-like properties of the ERalpha:tamoxifen complex, whereas an increase in the amount of ERbeta is associated with tamoxifen-resistant breast cancer. We have addressed each of these hypotheses by examining well characterized laboratory models. We determined whether changes in endogenous ERbeta are responsible for the estrogen-like or antiestrogenic properties of tamoxifen or raloxifene in MDA-MB-231 cells transfected with cDNAs for ERalpha or mutants D351G, D351Y. We found that the amount of ERbeta mRNA in separate, stable transfectants of mutant ERalpha cDNA was always < 2% of ERalpha. Since at least a 50:50 mixture of ERalpha:ERbeta is needed to silence the tamoxifen:ERalpha complex, we conclude that insufficient ERbeta mRNA is available for selective ER modulation in stable transfectants of D351G and D351Y ERalpha. Similarly, to test the hypothesis that ERbeta is up-regulated and plays an important role during the development of tamoxifen-stimulated tumor growth, we quantitatively analyzed ERbeta and ERalpha mRNA in tamoxifen-naïve (MCF-7:E2, ECC1:E2) and tamoxifen-stimulated tumors (MCF-7:TAM, EnCa 101:TAM). We found that ERbeta mRNA levels were not significantly elevated in tamoxifen-stimulated tumors and the ERalpha mRNA remained over 99% out of all ER species for all the tumors tested. The same results were also obtained when mRNA levels of ERbeta and ERalpha in a series of tamoxifen-naïve and tamoxifen-resistant breast cancer was analyzed. We conclude that endogenous ERbeta may not play a dominant role in the modulation of the tamoxifen ERalpha complex, or in the development of tamoxifen-stimulated resistant tumor growth.

Animals↗
PubMed2004

New targets for therapy in breast cancer: farnesyltransferase inhibitors.

Current systemic therapies for breast cancer are often limited by their nonspecific mechanism of action, unwanted toxicities on normal tissues, and short-term efficacy due to the emergence of drug resistance. However, identification of the molecular abnormalities in cancer, in particular the key proteins involved in abnormal cell growth, has resulted in development of various signal transduction inhibitor drugs as new treatment strategies against the disease. Protein farnesyltransferase inhibitors (FTIs) were originally designed to target the Ras signal transduction pathway, although it is now clear that several other intracellular proteins are dependent on post-translational farnesylation for their function. Preclinical data revealed that although FTIs inhibit the growth of ras-transformed cells, they are also potent inhibitors of a wide range of cancer cell lines that contain wild-type ras, including breast cancer cells. Additive or synergistic effects were observed when FTIs were combined with cytotoxic agents (in particular the taxanes) or endocrine therapies (tamoxifen). Phase I trials with FTIs have explored different schedules for prolonged administration, and dose-limiting toxicities included myelosuppression, gastrointestinal toxicity and neuropathy. Clinical efficacy against breast cancer was seen for the FTI tipifarnib in a phase II study. Based on promising preclinical data that suggest synergy with taxanes or endocrine therapy, combination clinical studies are now in progress to determine whether FTIs can add further to the efficacy of conventional breast cancer therapies.

Alkyl and Aryl Transferases↗
PubMed2004

The use of selective estrogen receptor modulators and selective estrogen receptor down-regulators in breast cancer.

Tamoxifen is one of the most effective treatments for breast cancer through its ability to antagonize estrogen-dependent growth by binding estrogen receptors (ERs) and inhibiting proliferation of breast epithelial cells. However, tamoxifen has estrogenic agonist effects in other tissues such as bone and endometrium due to liganded ER activating target genes in these different types of cell. Several novel anti-estrogen compounds have been developed which have a reduced agonist profile on breast and gynaecological tissues. These compounds offer the potential for enhanced efficacy and reduced toxicity compared with tamoxifen. In advanced breast cancer clinical data exist for two groups of agents: the selective estrogen receptor modulators (SERMs), further divided into "tamoxifen-like" (e.g. toremifene, droloxifene and idoxifene) and "fixed ring" compounds (e.g. raloxifene, arzoxifene and EM-800), and the selective estrogen receptor down-regulators (SERDs; e.g. fulvestrant (ICI 182780), SR 16234 and ZK 191703) also termed "pure anti-estrogens". In phase II trials in tamoxifen-resistant metastatic breast cancer the SERMs show low objective response rates (range 0-15%), suggesting cross resistance with tamoxifen. Randomized phase III trials for toremifene and idoxifene in over 1500 patients showed no significant difference compared with tamoxifen. Fewer clinical data exist for the "fixed ring" SERMs and it remains unclear whether any clinical advantage exists for the "fixed ring" SERMs over tamoxifen as first-line therapy. The main advantage for SERMs such as tamoxifen and raloxifene probably remains in early-stage disease (adjuvant therapy or prevention). Fulvestrant and the other SERDs have a high affinity for the estrogen receptor (ER) compared to tamoxifen, but none of its agonist activities. Of the SERDs, only fulvestrant has entered the clinic and this new agent is showing promising clinical activity in the treatment of advanced breast cancer. Recently published phase III studies have shown fulvestrant to be at least as effective as the third-generation aromatase inhibitor anastrozole in patients whose disease has relapsed or progressed on prior endocrine therapy. Surprisingly, however, in a phase III trial versus tamoxifen for the first-line therapy of advanced breast cancer fulvestrant did not attain the requirements for equivalence to tamoxifen, and in terms of time-to-treatment failure was inferior (5.9 versus 7.8 months for fulvestrant and tamoxifen, respectively; P=0.029). Future clinical studies will evaluate fulvestrant in the neoadjuvant setting together with its optimal sequencing in relation to tamoxifen and other endocrine therapies in advanced disease.

Antineoplastic Agents, Hormonal↗
PubMed2004

Ovarian cancer: review of the National Institute for Clinical Excellence (NICE) guidance recommendations.

The National Institute for Clinical Excellence (NICE), established in 1996 as a special Health Authority for England and Wales, provides the United Kingdom medical community with robust and reliable guidance on current "best practices" in medicine. Based on analyses of clinical efficacy, safety, and cost effectiveness, clinical guideline recommendations are developed in an attempt to standardize treatment of various diseases and medical conditions. To date, NICE has issued guidance for the use of three chemotherapeutic agents in the treatment of ovarian cancer: paclitaxel, topotecan, and pegylated liposomal doxorubicin. NICE guidance recommends surgery and adjuvant chemotherapy with paclitaxel/platinum combination therapy or platinum therapy alone as first-line treatment for ovarian cancer. NICE has also issued guidance recommending the use of topotecan or pegylated liposomal doxorubicin as second-line agents for the treatment of women with relapsed or refractory disease. Accounting for all available data, NICE guidance supports the appropriate roles of paclitaxel, topotecan, and pegylated liposomal doxorubicin in the treatment of advanced ovarian cancer.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2003

Comparison of the selective estrogen receptor modulator arzoxifene (LY353381) with tamoxifen on tumor growth and biomarker expression in an MCF-7 human breast cancer xenograft model.

Arzoxifene (ARZ) is a selective estrogen receptor (ER) modulator with greater bioavailability than raloxifene which is being developed as treatment for breast cancer. We have used an in vivo model of hormone-sensitive breast cancer to study the growth-inhibitory and pharmacodynamic effects of ARZ in comparison with the most widely used antiestrogen, tamoxifen (TAM). We compared the abilities of ARZ and TAM to antagonize the estrogen (E2)-dependent growth of MCF-7 human breast cancer xenografts in oophorectomized athymic mice. At four different time points over 28 days, we studied their time-related pharmacodynamic effects on biomarkers of tumor growth (cell proliferation/death measured by Ki-67 and apoptosis scores), cell cycle activity (cyclin D1 and p27(kip1)), and hormone-regulated gene expression (ERalpha, progesterone receptor, and pS2). Although maximal growth inhibition was seen after E2 withdrawal, ARZ and TAM induced significant and similar inhibition of E2-stimulated tumor growth. Inhibition of growth was reflected by changes in the tumor growth index (ratio posttreatment/pretreatment Ki-67/apoptosis scores). ARZ and TAM resulted in a significant (P < 0.001) increase in ER expression and reduction in progesterone receptor expression, whereas changes in cyclin D1 score were inversely related to p27(kip1) score. A significant but delayed biological effect was observed with a 10-fold lower dose of ARZ. These results show that ARZ is an effective antagonist of E2-stimulated breast cancer growth with similar growth-inhibitory and pharmacodynamic effects to TAM in this model.

Animals↗
PubMed2003

Phase II study of the efficacy and tolerability of two dosing regimens of the farnesyl transferase inhibitor, R115777, in advanced breast cancer.

PURPOSE: R115777 is an orally active farnesyl transferase inhibitor that specifically blocks farnesylation of proteins involved in growth-factor-dependent cell-signal-transduction pathways. We conducted a phase II study in 76 patients with advanced breast cancer. PATIENTS AND METHODS: Two cohorts of patients were recruited sequentially. The first cohort (n = 41) received a continuous dosing [CD] regimen of R115777 400 or 300 mg bid. The second cohort (n = 35) received 300 mg bid in a cyclical regimen of 21 days of treatment followed by 7 days of rest (intermittent dosing [ID]). RESULTS: In the CD cohort, four patients (10%) had a partial response (PR) and six patients (15%) had stable disease at > or = 24 weeks (SD). In the ID cohort, five patients (14%) had a PR and three patients (9%) had prolonged SD. The first six patients in the CD cohort treated at 400 mg bid all developed grade 3 to 4 neutropenia, so the subsequent 35 patients were treated at 300 mg bid. The incidence of hematologic toxicity was significantly lower in the ID than in the CD (300-mg bid) cohort: grade 3 to 4 neutropenia (14% v 43%; P =.016) and grade 3 to 4 thrombocytopenia (3% v 26%; P =.013). One patient in the ID cohort developed grade 2 to 3 neurotoxicity compared with 15 patients in the CD cohort (3% v 37%; P =.0004). CONCLUSION: The farnesyl transferase inhibitor R115777 has demonstrated clinical activity in patients with metastatic breast cancer, and the ID regimen has a significantly improved therapeutic index compared with the CD regimen.

Administration, Oral↗
PubMed2003

Enhanced estrogen receptor (ER) alpha, ERBB2, and MAPK signal transduction pathways operate during the adaptation of MCF-7 cells to long term estrogen deprivation.

The mechanisms involved in resistance to estrogen deprivation are of major importance for optimal patient therapy and the development of new drugs. Long term culture of MCF-7 cells in estrogen (E2)-depleted medium (long term estrogen deprivation; LTED) results in hypersensitivity to E2 coinciding with elevated levels of estrogen receptor (ER) alpha phosphorylated on Ser118 and MAPK, together with several of its downstream targets associated previously with ERalpha phosphorylation. Our data suggest elevated MAPK activity results from enhanced ERBB2 expression in the LTED cells versus the wild-type (wt), and treatment with the tyrosine kinase inhibitor ZD1839 revealed increased sensitivity in both transcription and proliferation assays. Similarly the MEK inhibitor U0126 decreased transcription and proliferation in the LTED cells and reduced their sensitivity to the proliferative effects of E2, while having no effect on the wt. However, the complete suppression of MAPK activity in the LTED cells did not inhibit ERalpha Ser118 phosphorylation suggesting that ER activity remained ligand-dependant. The LTED cells also expressed elevated levels of insulin-like growth factor-1R, and inhibition of phosphatidylinositol 3-kinase activity with LY294002 reduced basal ERalpha transactivation by 70% in the LTED cells compared with the wt. However, LY294002 had no effect on ERalpha Ser118 phosphorylation. These data suggest that although elevated levels of MAPK occur during LTED and influence the phenotype, this is unlikely to be the sole pathway operating to achieve adaptation.

Adaptation, Physiological↗
PubMed2003

Novel systemic therapies for breast cancer.

The rapid expansion in our knowledge of the molecular pathogenesis of cancer has created several opportunities for novel strategies in anti-cancer drug design and development. Recent developments have included a series of new endocrine therapies such as pure anti-oestrogens and selective oestrogen receptor modulators, and trials are in progress to determine their role in the sequence of therapies given the first-line role now occupied by the aromatase inhibitors. Novel cytotoxic drugs have been developed with an improved toxicity profile, including oral prodrugs that are activated within tumour cells, and liposomal delivery mechanisms for conventional drugs that reduce some of the systemic toxicities. There has been much success with monoclonal antibodies targeted against growth factor receptors, both as monotherapy and in enhancing the efficacy of cytotoxic drugs. A number of small molecule signal transduction inhibitors are in early stages of clinical development for breast cancer, including tyrosine-kinase inhibitors and farnesyl transferase inhibitors. Emerging pre-clinical evidence suggests that these drugs may best be used in combination with endocrine therapy. Other novel strategies that are being tested include vaccines and anti-angiogenesis drugs. As these new therapies evolve towards the clinic, the challenge to oncologists is whether their potential seen in the laboratory can be matched by further substantial improvements in clinical outcome.

Adult↗