Predicting the course of functional limitation among older adults with knee pain: do local signs, symptoms and radiographs add anything to general indicators?

OBJECTIVE

To determine the additional prognostic value of clinical history, physical examination and x-ray findings to a previously derived simple generic model (age, body mass index, anxiety and pain severity) in a cohort of older adults with knee pain.

METHODS

Prospective cohort study in community-dwelling adults in North Staffordshire. 621 participants (aged >or=50 years) reporting knee pain who attended a research clinic at recruitment and were followed up by postal questionnaire at 18 months. Poor functional outcome was measured by the Physical Functioning Scale of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at 18-month follow-up defined in 60% of participants.

RESULTS

Three clinical history variables (bilateral knee pain, duration of morning stiffness and inactivity gelling) were independently associated with poor outcome. The addition of the "clinical history" model to the "generic" model led to a statistical improvement in model fit (likelihood ratio (LR) = 24.84, p = 0.001). Two physical examination variables (knee tender point count and single-leg balance) were independently associated with poor outcome but did not lead to a significant improvement when added to the "clinical history and generic" model (LR = 6.34, p = 0.50). Functional outcome was significantly associated with severity of knee radiographic osteoarthritis (OA), but did not lead to any improvement in fit when added to the "generic, clinical history and physical examination" model (LR = 1.86, p = 0.39).

CONCLUSIONS

Clinical history, physical examination and severity of radiographic knee OA are of limited value over generic factors when trying to predict which older adults with knee pain will experience progressive or persistent functional difficulties.

Psychogenic nonepileptic seizures in patients with learning disability: comparison with patients with no learning disability

Among a consecutive series of patients with psychogenic nonepileptic seizures (PNES), we compared patients with learning disability (LD) (n=25) with patients with no LD (n=263), with respect to demographic and clinical variables. A higher proportion of the LD group had epilepsy as well as PNES (P<0.001) (uncorrected P values are quoted), and a higher proportion were taking antiepileptic drugs at the time of diagnosis of PNES (P=0.007). Fewer patients with LD had a history of antecedent sexual abuse (P=0.036). A higher proportion of the LD group had previous pseudostatus (P<0.001), and a higher proportion had immediate situational or emotional triggers for their attacks (P<0.001). There were trends toward a higher proportion of men in the LD group (P=0.056) and a longer delay between onset of PNES and diagnosis (P=0.072). Our data suggest potentially important clinical differences between PNES populations with and without LD, as well as possible differences in mechanism.

Characterisation and protein expression profiling of annexins in colorectal cancer

The annexins are family of calcium-regulated phospholipid-binding proteins with diverse roles in cell biology. Individual annexins have been implicated in tumour development and progression, and in this investigation a range of annexins have been studied in colorectal cancer. Annexins A1, A2, A4 and A11 were identified by comparative proteomic analysis to be overexpressed in colorectal cancer. Annexins A1, A2, A4 and A11 were further studied by immunohistochemistry with a colorectal cancer tissue microarray containing primary and metastatic colorectal cancer and also normal colon. There was significant increase in expression in annexins A1 (P=0.01), A2 (P<0.001), A4 (P<0.001) and A11 (P<0.001) in primary tumours compared with normal colon. There was increasing expression of annexins A2 (P=0.001), A4 (P=0.03) and A11 (P=0.006) with increasing tumour stage. An annexin expression profile was identified by k-means cluster analysis, and the annexin profile was associated with tumour stage (P=0.01) and also patient survival. Patients in annexin cluster group 1 (low annexin expression) had a better survival (log rank=5.33, P=0.02) than patients in cluster group 2 (high annexins A4 and A11 expression). In conclusion, this study has shown that individual annexins are present in colorectal cancer, specific annexins are overexpressed in colorectal cancer and the annexin expression profile is associated with survival.

Congenital talipes equinovarus: a review of current management

Talipes equinovarus is one of the more common congenital abnormalities affecting the lower limb and can be challenging to manage. This review provides a comprehensive update on idiopathic congenital talipes equinovarus with emphasis on the initial treatment. Current management is moving away from operative towards a more conservative treatment using the Ponseti regime. The long-term results of surgical correction and the recent results of conservative treatment will be discussed.

Transcriptome analysis during the process ofin vitrodifferentiation ofLeishmania donovaniusing genomic microarrays

Leishmania donovanicauses visceral disease (kala-azar), a major health problem throughout the tropics with 500 000 new cases every year.Leishmaniadifferentiates from the promastigote to the amastigote form to establish infection in a mammalian host. To understand the process of differentiation, we assessed the global variation in gene expression in promastigotes, an intermediate stage of differentiation (PA24) and axenic amastigotes in culture using anL. donovanigenomic microarray with 4224 clones printed in triplicate. During an intermediate stage of differentiation 24 h after shifting the promastigotes into amastigotes (PA24), there were 41 (∼1%) clones with expression ⩾2·0-fold higher than promastigotes, whereas in terminally differentiated amastigotes there were 130 (∼3%) such clones. Of particular interest were certain genes that exhibited a transient increase or decrease in expression at the PA24 stage. Kinases showed a transient increase, and surface molecules, PSA and amino acid permease, were prominent clones among those showing a brief decrease at the PA24 stage. The microarray results have been validated using Northern blots or RT-PCR. In summary, our results provide important clues about the genes involved in the differentiation process ofL. donovanithat may contribute to virulence.

Knee osteoarthritis in community-dwelling older adults: are there characteristic patterns of pain location?

OBJECTIVE

To determine whether there are characteristic patterns of pain location associated with knee osteoarthritis (OA) among community-dwelling older adults.

DESIGN

Population-based, cross-sectional survey of 697 adults aged 50 years and over reporting knee pain within the past 6 months. Pain at 13 individual sites at or around the knee was coded. Pain locations in participants with and without "symptomatic knee OA" (defined as symptoms on most days in the past month, at least a definite osteophyte on plain X-ray, and current pain intensity of at least 2 out of 10) were compared. Participants were then grouped by pattern of knee pain location, and their clinical and radiographic characteristics compared.

RESULTS

Generalised knee pain (n=313) and medial knee pain (either in isolation or with peripatellar or lateral knee pain: n=175) were the most common patterns. Medial knee pain and distally radiating pain were significantly more likely in those with symptomatic knee OA. Individuals with generalised knee pain with radiation had more persistent, severe pain, and a relatively high proportion had moderate or severe radiographic disease.

CONCLUSION

No single pattern of pain location is pathognomonic for knee OA. Attention towards the role of peripheral nociception and central sensitisation in producing medial knee pain and distally radiating knee pain is warranted.

Optimization of the use of C57BL/6 mice as a laboratory animal model for Neospora caninum vaccine studies

The development and testing of vaccines for Neospora caninum in mice require challenge studies to demonstrate a reduction in clinical signs or prevention of vertical transmission of the parasite after vaccination. Genetic susceptibility to N. caninum varies with the strain of mice. In this study, C57BL/6 mice were evaluated as a model for Neospora vaccine studies. A lethal challenge model was developed and the LD(50) was determined to be 1.5 x 10(7)N. caninum tachyzoites/mouse, delivered intraperitoneally. Brain lesions encountered in sections from sub-lethally challenged mice were scored on the basis of severity and total number of lesions to develop a histopathological scoring system for vaccine efficacy. A vertical transmission model for N. caninum vaccine studies was developed by studying mice that were infected either 2 weeks prior to mating or between days 12 and 14 of pregnancy. It was found that infection prior to mating reduced the average number of pups per litter. DNA extracted from fetal tissue was examined by a N. caninum specific polymerase chain reaction (PCR). The rate of vertical transmission was 0, 100 and 90.5% for the uninfected controls, mice infected during pregnancy and mice infected before mating, respectively. This study demonstrates that the C57BL/6 strain of mice is a good model for N. caninum vaccine studies because it is possible to establish a clear-cut lethal challenge model in C57BL/6 mice and they transmit the disease to their offspring efficiently.

Simple methods for assessing haplotype-environment interactions in case-only and case-control studies

For investigating haplotype-environment interactions in case-control studies, one can implement statistical methods based either on a retrospective likelihood (modeling the probability of haplotype and environment conditional on disease status) or a prospective likelihood (modeling the probability of disease status conditional on haplotype and environment). Retrospective approaches are generally more powerful than prospective approaches, but require an explicit model of the joint distribution of haplotype and environmental factors in the sample with the latter being particularly unattractive to specify. To resolve this issue, we propose a number of simple retrospective procedures for haplotype-environment interaction analysis that do not require explicit modeling of environmental covariates in the sample. We first consider a cases-only procedure, followed by a simple likelihood for case-control data that is proportional to the full-retrospective likelihood. Finally, we consider a retrospective procedure for inference on haplotype-environment interaction effects in matched or finely-stratified case-control studies. Our methods are based on the assumptions that haplotypes and environmental covariates are independent in the target population and that disease is rare. We illustrate our approaches using case-control data from the Finland-United States Investigation of Non-Insulin Dependent Diabetes Mellitus (FUSION) genetic study and simulated data.

Synthesis and biological in vitro evaluation of novel PEG-psoralen conjugates

Psoralens are well-known photosensitizers, and 8-methoxypsoralen and 4,5',8-trimethylpsoralen are widely used in photomedicine as "psoralens plus UVA therapy" (PUVA), in photopheresis, and in sterilization of blood preparations. In an attempt to improve the therapeutic efficiency of PUVA therapy and photopheresis, four poly(ethylene glycol) (PEG)-psoralen conjugates were synthesized to promote tumor targeting by the enhanced permeability and retention (EPR) effect. Peptide linkers were used to exploit specific enzymatic cleavage by lysosomal proteases. A new psoralen, 4-hydroxymethyl-4',8-dimethylpsoralen (6), suitable for polymer conjugation was synthesized. The hydroxy group allowed exploring different strategies for PEG conjugation, and linkages with different stability such ester or urethanes were obtained. PEG (5 kDa) was covalently conjugated to the new psoralen derivative using four different linkages, namely, (i) direct ester bond (7), (ii) ester linkage with a peptide spacer (8), (iii) a carbamic linker (9), and (iv) a carbamic linker with a peptide spacer (12). The stability of these new conjugates was assessed at different pHs, in plasma and following incubation with cathepsin B. Conjugates 7 and 8 were rapidly hydrolyzed in plasma, while 9 was stable in buffer and in the presence of cathepsin B. As expected, only the conjugates containing the peptide linker released the drug in presence of cathepsin B. In vitro evaluation of the cytotoxic activity in the presence and absence of light was carried out in two cell lines (MCF-7 and A375 cells). Conjugates 7 and 8 displayed a similar activity to the free drug (probably due to the low stability of the ester linkage). Interestingly, the conjugates containing the carbamate linkage (9 and 12) were completely inactive in the dark (IC50 > 100 microM in both cell lines). However, antiproliferative activity become apparent after UV irradiation. Conjugate 12 appears to be the most promising for future in vivo evaluation, since it was relatively stable in plasma, which should allow tumor targeting and drug release to occur by cathepsin B-mediated hydrolysis.

Designing polymer conjugates as lysosomotropic nanomedicines

Marriage of cell biology (the concept of ‘lysosomotropic drug delivery’) and the realization that water-soluble synthetic polymers might provide an ideal platform for targeted drug delivery led to the first synthetic polymer–drug conjugates that entered clinical trials as anticancer agents. Conceptually, polymer conjugates share many features with other macromolecular drugs, but they have the added advantage of the versatility of synthetic chemistry that allows tailoring of molecular mass and addition of biomimetic features. Conjugate characteristics must be optimized carefully to ensure that the polymeric carrier is biocompatible and that the polymer molecular mass enables tumour-selective targeting followed by endocytic internalization. The polymer–drug linker must be stable in transit, but be degraded at an optimal rate intracellularly to liberate active drug. Our early studies designed two HPMA [N-(2-hydroxypropyl)methacrylamide] copolymer conjugates containing doxorubicin that became the first synthetic polymer–drug conjugates to be tested in phase I/II clinical trials. Since, a further four HPMA copolymer–anticancer drug conjugates (most recently polymer platinates) and the first polymer-based γ-camera imaging agents followed. Polymer–drug linkers cleaved by lysosomal thiol-dependent proteases and the reduced pH of endosomes and lysosomes have been used widely to facilitate drug liberation. It is becoming clear that inappropriate trafficking and/or malfunction of enzymatic activation can lead to new mechanisms of clinical resistance. Recent studies have described HPMA copolymer conjugates carrying a combination of both endocrine and chemotherapy that are markedly more active than individual conjugates carrying a single drug. Moreover, current research is investigating novel dendritic polymer architectures and novel biodegradable polymers as drug carriers that will provide improved drug delivery and imaging probes in the future. The present paper reviews the clinical status of polymeric anticancer agents, the rationale for the design of polymer therapeutics and discusses the benefits and challenges of lysosomotropic delivery.

Symptoms and radiographic osteoarthritis: not as discordant as they are made out to be?

OBJECTIVES

Joint pain and radiographic osteoarthritis are often discordant.

AIM

To investigate this issue more closely by studying the detailed nature of pain and disability, and how this relates to radiographic osteoarthritis.

METHODS

Population-based study of 819 adults aged >or=50 years with knee pain. The severity of knee pain, stiffness and disability was measured using a validated scale (the Western Ontario and McMaster Universities (WOMAC) Score) and pain persistence was recorded. Global severity was measured by the graded chronic pain scale. Three radiographic views of the knees were obtained-weight-bearing posteroanterior metatarsophalangeal, supine skyline and supine lateral.

RESULTS

745 participants with knee pain in the past 6 months were eligible (mean age 65 years, 338 men). Radiographic osteoarthritis was more common in those with a longer history and more persistent symptoms. A strong trend was found of radiographic osteoarthritis being more strongly associated with higher WOMAC scores for pain severity, stiffness and disability (adjusted odds ratio (95% confidence interval (CI)) for highest v lowest WOMAC category: 3.7 (2.0 to 6.7), 3.0 (2.0 to 4.6) and 2.8 (1.6 to 5.0), respectively). Those individual WOMAC items for pain and disability pertaining to weight-bearing mobility were the most strongly associated with radiographic osteoarthritis. Combining pain persistence and global severity, persistent severe pain was associated with a significant increase in the occurrence of radiographic osteoarthritis (2.6 (95% CI 1.5 to 4.7)).

CONCLUSIONS

A consistent association was found between severity of pain, stiffness and physical function and the presence of radiographic osteoarthritis. This study highlights the potential contribution of underlying joint disease to the degree of pain and disability.

Lack of augmentation of tumor spectrum or severity in dual heterozygous Men1 and Rb1 knockout mice

To identify possible genetic interactions between the mechanisms of tumor suppression of menin and pRb, we intercrossed mice with targeted deletions of Men1 and Rb1, and compared tumor development in cohorts of animals carrying single or dual mutations of these tumor-suppressor genes. In mice lacking one copy of Men1, pancreatic islet and anterior pituitary adenomas are common. In animals lacking one copy of Rb1, intermediate pituitary and thyroid tumors occur at high frequency, with less frequent development of pancreatic islet hyperplasia and parathyroid lesions. In mice heterozygous for both Men1 and Rb1, pancreatic hyperplasia and tumors of the intermediate pituitary and thyroid occurred at high frequency. Serum measurements of calcium and glucose did not vary significantly between genotypic groups. Loss of heterozygosity at the Rb1 locus was common in pituitary and thyroid tumors, whereas loss of menin was observed in pancreatic and parathyroid lesions. The tumor spectrum in the double heterozygotes was a combination of pathologies seen in each of the individual heterozygotes, without decrease in age of onset, indicating independent, non-additive effects of the two mutations. Together with the lack of increased tumor spectrum, this suggests that menin and pRb function in a common pathway of tumor suppression.

Electrical conductivities of the freshly excised cerebral cortex in epilepsy surgery patients; correlation with pathology, seizure duration, and diffusion tensor imaging

The electrical conductivities (sigma) of freshly excised neocortex and subcortical white matter were studied in the frequency range of physiological relevance for EEG (5-1005 Hz) in 21 patients (ages 0.67 to 55 years) undergoing epilepsy neurosurgery. Surgical patients were classified as having cortical dysplasia (CD) or non-CD pathologies. Diffusion tensor imaging (DTI) for apparent diffusion coefficient (ADC) and fractional anisotropy (FA) was obtained in 9 patients. Results found that electrical conductivities in freshly excised neocortex vary significantly from patient to patient (sigma = 0.0660-0.156 S/m). Cerebral cortex from CD patients had increased conductivities compared with non-CD cases. In addition, longer seizure durations positively correlated with conductivities for CD tissue, while they negatively correlated for non-CD tissue. DTI ADC eigenvalues inversely correlated with electrical conductivity in CD and non-CD tissue. These results in a small initial cohort indicate that electrical conductivity of freshly excised neocortex from epilepsy surgery patients varies as a consequence of clinical variables, such as underlying pathology and seizure duration, and inversely correlates with DTI ADC values. Understanding how disease affects cortical electrical conductivity and ways to non-invasively measure it, perhaps through DTI, could enhance the ability to localize EEG dipoles and other relevant information in the treatment of epilepsy surgery patients.

Clinical classification criteria for knee osteoarthritis: performance in the general population and primary care

BACKGROUND

Doubts have been expressed about the performance of the American College of Rheumatology (ACR) clinical classification criteria for osteoarthritis when applied in the general population.

OBJECTIVE

To investigate whether the distribution of population subgroups and underlying disease severity might explain the performance of these criteria in the population setting.

METHODS

Population-based cross-sectional study. 819 adults aged > or = 50 years reporting knee pain in the last 12 months were clinically assessed by research therapists using standardised protocols and blinded to radiographic status. All participants underwent plain radiography of the knees, scored by a single reader blinded to clinical status. The relationship between fulfilling the ACR clinical classification criteria for knee osteoarthritis and the presence of symptomatic radiographic knee osteoarthritis was summarised for the sample as a whole and within subgroups.

RESULTS

Radiographic osteoarthritis was present in 539 participants (68%) and symptomatic radiographic knee osteoarthritis in 259 (33%). 238 participants (30%) fulfilled the ACR clinical criteria for knee osteoarthritis. Agreement between the ACR clinical criteria and symptomatic radiographic knee osteoarthritis was low (sensitivity 41%; specificity 75%; positive predictive value 44%; negative predictive value 72%). Sensitivity and specificity did not vary markedly between population subgroups, although they were influenced by the underlying severity of radiographic osteoarthritis.

CONCLUSION

The ACR clinical criteria seem to reflect later signs in advanced disease. Other approaches may be needed to identify early, mild osteoarthritis in the general population and primary care.

Cellular immune response to pulmonary infections in HIV-infected individuals hospitalized with diverse grades of immunosuppression

The lymphocyte profile of 521 HIV-infected subjects hospitalized at Jackson Memorial (2001-2002) was compared across main respiratory diseases. Study data included medical history and all laboratory evaluations performed during hospitalization. Community-acquired pneumonias (CAP, 52%), Pneumocystis jiroveci pneumonia (PCP, 24%), tuberculosis (TB, 9%) and non-tuberculous mycobacterial diseases (NTM, 12%) were the most frequent causes of admission. Patients hospitalized with PCP and NTM exhibited the lowest CD4 counts (P=0.003). PCP patients had the highest B-cell percentages (P=0.04). CAP patients had the highest CD8 and CD4 percentages and the lowest percentage of Natural Killer (NK) cells and viral burdens. TB patients exhibited the lowest NK-cell (11.4+/-6.3) and B-cell percentages (13.6+/-12) and the highest CD8 (59+/-14) percentage. NTM patients, in contrast, had the highest NK-cell percentages of the groups (19.1+/-11.6, P=0.01). Additionally, immune responses associated with respiratory pathogens differed in HIV-infected patients with CD4(+) cells above and below 200 counts.

The safety of antiepileptic drug withdrawal in patients with non-epileptic seizures

BACKGROUND

To determine whether withdrawal of anticonvulsant drugs (AED) can be carried out safely in patients with non-epileptic seizures (NES).

METHODS

Prospective evaluation of safety and outcome in 78 patients with NES who satisfied a standardised set of criteria for excluding the diagnosis of coexisting or underlying epilepsy.

FINDINGS

The patients were taking from one to three AED. Sixty four patients were withdrawn as outpatients, 14 as inpatients. Five patients stopped their drugs abruptly, and two had AED restarted and had to be withdrawn again. Otherwise all patients adhered to withdrawal schedules. A new type of attack in addition to NES was seen in three patients (complex partial seizures in all three cases). NES frequency declined in the group as a whole over the period of the study (follow up 6-12 months) in all individuals except for eight patients in whom there was a transient increase. Fourteen patients reported new physical symptoms after withdrawal; however, no serious adverse events were reported.

CONCLUSIONS

With appropriate diagnostic investigation and surveillance during follow up withdrawal of AED can be achieved safely in patients with NES.

Review of patients in general practice with a diagnosis of epilepsy: development of a practice nurse checklist and an assessment of resource implications

BACKGROUND

SIGN has recommended annual review of all patients with epilepsy. Annual review is rewarded in the new GMS contract. There is no information on how or by whom reviews should be carried out, nor on resource implications for secondary care.

AIMS

To determine whether a practice nurse can deliver annual review of patients with epilepsy, and to estimate the resource implications of such review.

METHODS

Evaluation of a practice nurse checklist against review by neurologist in 62 patients with epilepsy identified from a practice list of 6240 from Southwest Glasgow LHCC, and audit of case records in 1259 patients with epilepsy identified from the whole LHCC population of 96,565.

RESULTS

There were 8 discrepancies between nurse and doctor reviews in a first iteration, but none in the second. Changes suggested a training effect. The review process generated 19 epilepsy nurse appointments, 7 requests for cerebral imaging and 3 requests for video EEG. Twelve patients required continuing follow up. The LHCC audit identified a large number of patients who had inadequate documentation of information and advice (over 90% in some domains). 28.6% had not been seen by a specialist, 40.7% had not had cerebral imaging, and only 37.4% were seizure free.

CONCLUSION

Annual reviews of patients with epilepsy can be carried out by practice nurses, but some training is required. The review process is likely to increase the burden on secondary care and have a significant adverse effect on neurology waiting times.

Polymer-drug conjugates: towards a novel approach for the treatment of endrocine-related cancer

The last decade has seen successful clinical application of polymer-protein conjugates (e.g. Oncaspar, Neulasta) and promising results in clinical trials with polymer-anticancer drug conjugates. This, together with the realisation that nanomedicines may play an important future role in cancer diagnosis and treatment, has increased interest in this emerging field. More than 10 anticancer conjugates have now entered clinical development. Phase I/II clinical trials involving N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-doxorubicin (PK1; FCE28068) showed a four- to fivefold reduction in anthracycline-related toxicity, and, despite cumulative doses up to 1680 mg/m2 (doxorubicin equivalent), no cardiotoxicity was observed. Antitumour activity in chemotherapy-resistant/refractory patients (including breast cancer) was also seen at doxorubicin doses of 80-320 mg/m2, consistent with tumour targeting by the enhanced permeability (EPR) effect. Hints, preclinical and clinical, that polymer anthracycline conjugation can bypass multidrug resistance (MDR) reinforce our hope that polymer drugs will prove useful in improving treatment of endocrine-related cancers. These promising early clinical results open the possibility of using the water-soluble polymers as platforms for delivery of a cocktail of pendant drugs. In particular, we have recently described the first conjugates to combine endocrine therapy and chemotherapy. Their markedly enhanced in vitro activity encourages further development of such novel, polymer-based combination therapies. This review briefly describes the current status of polymer therapeutics as anticancer agents, and discusses the opportunities for design of second-generation, polymer-based combination therapy, including the cocktail of agents that will be needed to treat resistant metastatic cancer.

Consensus statement. Workshop on therapeutic resistance in breast cancer: impact of growth factor signalling pathways and implications for future treatment

Anti-hormones (notably tamoxifen), chemotherapy and modern radiotherapeutic approaches are invaluable in the management of breast cancer, and collectively have contributed substantially to the improved survival in this disease. Moreover, there is promise that these successes will continue with the emergence of other endocrine agents (for example, aromatase inhibitors and pure anti-oestrogens). However, de novo and acquired resistance comprises a significant problem with all treatment approaches examined to date. This Workshop aimed to evaluate the contribution made by growth factor signalling pathways in the various resistant states, primarily focusing on resistance to anti-hormonal strategies and spanning experimental models and, where possible, clinical breast cancer data. The successes and limitations of therapeutic targeting of these pathways with various signal transduction inhibitors (STIs) were evaluated in model systems and from emerging clinical trials (including epidermal growth factor receptor inhibitors such as gefitinib). It was concluded that growth factor signalling is an important contributor in the development of endocrine resistance in breast cancer and that use of STIs provides a promising therapeutic strategy for this disease. However, the cancer cell is clearly able to harness alternative growth factor signalling pathways for growth and cell survival in the presence of STI monotherapy and, as a consequence, the efficacy of STIs is likely to be limited by the acquisition of resistance. A number of strategies were proposed from studies in model systems that appeared to enhance anti-tumour actions of existing STI monotherapy, notably including combination therapies targeting multiple pathways. With the increased availability of diverse STIs and improved drug delivery, there is much hope that the more complex therapeutic strategies proposed may ultimately be achievable in clinical practice.