ABSTRACT
Abiraterone acetate plus prednisolone (AAP) previously demonstrated improved survival in STAMPEDE, a multiarm, multistage platform trial in men starting long-term hormone therapy for prostate cancer. This long-term analysis in metastatic patients was planned for 3 years after the first results. Standard-of-care (SOC) was androgen deprivation therapy. The comparison randomised patients 1:1 to SOC-alone with or without daily abiraterone acetate 1000 mg + prednisolone 5 mg (SOC + AAP), continued until disease progression. The primary outcome measure was overall survival. Metastatic disease risk group was classified retrospectively using baseline CT and bone scans by central radiological review and pathology reports. Analyses used Cox proportional hazards and flexible parametric models, accounting for baseline stratification factors. One thousand and three patients were contemporaneously randomised (November 2011 to January 2014): median age 67 years; 94% newly-diagnosed; metastatic disease risk group: 48% high, 44% low, 8% unassessable; median PSA 97 ng/mL. At 6.1 years median follow-up, 329 SOC-alone deaths (118 low-risk, 178 high-risk) and 244 SOC + AAP deaths (75 low-risk, 145 high-risk) were reported. Adjusted HR = 0.60 (95% CI: 0.50-0.71; P = 0.31 × 10-9 ) favoured SOC + AAP, with 5-years survival improved from 41% SOC-alone to 60% SOC + AAP. This was similar in low-risk (HR = 0.55; 95% CI: 0.41-0.76) and high-risk (HR = 0.54; 95% CI: 0.43-0.69) patients. Median and current maximum time on SOC + AAP was 2.4 and 8.1 years. Toxicity at 4 years postrandomisation was similar, with 16% patients in each group reporting grade 3 or higher toxicity. A sustained and substantial improvement in overall survival of all metastatic prostate cancer patients was achieved with SOC + abiraterone acetate + prednisolone, irrespective of metastatic disease risk group.
Subject(s)
Prostatic Neoplasms, Castration-Resistant , Prostatic Neoplasms , Abiraterone Acetate/therapeutic use , Aged , Androgen Antagonists/therapeutic use , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Follow-Up Studies , Hormones , Humans , Male , Prednisolone/therapeutic use , Prednisone/therapeutic use , Prostatic Neoplasms/pathology , Prostatic Neoplasms, Castration-Resistant/drug therapy , Retrospective Studies , Treatment OutcomeABSTRACT
BACKGROUND: Immune checkpoint inhibitors (ICI) improve survival but cause immune-related adverse events (irAE). We sought to determine if CTCAE classification, IBD biomarkers/endoscopic/histological scores correlate with irAE colitis outcomes. METHODS: A dual-centre retrospective study was performed on patients receiving ICI for melanoma, NSCLC or urothelial cancer from 2012 to 2018. Demographics, clinical data, endoscopies (reanalysed using Mayo/Ulcerative Colitis Endoscopic Index of Severity (UCEIS) scores), histology (scored with Nancy Index) and treatment outcomes were analysed. RESULTS: In all, 1074 patients were analysed. Twelve percent (134) developed irAE colitis. Median patient age was 66, 59% were male. CTCAE diarrhoea grade does not correlate with steroid/ infliximab use. G3/4 colitis patients are more likely to need infliximab (p < 0.0001) but colitis grade does not correlate with steroid duration. CRP, albumin and haemoglobin do not correlate with severity. The UCEIS (p = 0.008) and Mayo (p = 0.016) scores correlate with severity/infliximab requirement. Patients with higher Nancy indices (3/4) are more likely to require infliximab (p = 0.03). CONCLUSIONS: CTCAE assessment does not accurately reflect colitis severity and our data do not support its use in isolation, as this may negatively impact timely management. Our data support utilising endoscopic scoring for patients with >grade 1 CTCAE disease, and demonstrate the potential prognostic utility of objective histologic scoring.
Subject(s)
Carcinoma, Non-Small-Cell Lung/drug therapy , Colitis/diagnosis , Immune Checkpoint Inhibitors/adverse effects , Melanoma/drug therapy , Aged , Carcinoma, Non-Small-Cell Lung/complications , Carcinoma, Non-Small-Cell Lung/pathology , Colitis/chemically induced , Colitis/diagnostic imaging , Colitis/pathology , Colonoscopy , Drug-Related Side Effects and Adverse Reactions , Female , Humans , Immune Checkpoint Inhibitors/administration & dosage , Infliximab/administration & dosage , Infliximab/adverse effects , Male , Melanoma/complications , Melanoma/pathology , Middle Aged , Prognosis , Severity of Illness Index , Treatment Outcome , Urothelium/drug effects , Urothelium/pathologyABSTRACT
OBJECTIVES: To map current practice regarding discussions around resuscitation across England and Scotland in patients with cancer admitted acutely to hospital and to demonstrate the value of medical students in rapidly collecting national audit data. METHODS: Collaborators from the Macmillan medical student network collected data from 251 patient encounters across eight hospitals in England and Scotland. Data were collected to identify whether discussion regarding resuscitation was documented as having taken place during inpatient admission to acute oncology. As an audit standard, it was expected that all patients should be invited to discuss resuscitation within 24 hr of admission. RESULTS: Resuscitation discussions were had in 43.1% of admissions and of these 64.0% were within 24 hr; 27.6% of all admissions. 6.5% of patients had a "do not attempt resuscitation" order prior to admission with a difference noted between patients receiving palliative and curative treatment (8.5% and 0.39%, respectively, p < .05). Discussions regarding escalation of care took place in only 29.3% of admissions. CONCLUSIONS: These data highlight deficiencies in the number of discussions regarding resuscitation that are being conducted with cancer patients that become acutely unwell. It also demonstrates the value of medical student collaboration in rapidly collecting national audit data.
Subject(s)
Advance Care Planning , Cardiopulmonary Resuscitation , Hospitalization , Neoplasms , Resuscitation Orders , Clinical Audit , Communication , Data Collection , England , Female , Humans , Male , Middle Aged , Oncology Service, Hospital , Professional-Patient Relations , Scotland , Students, MedicalABSTRACT
Bleomycin, a cytotoxic chemotherapy agent, forms a key component of curative regimens for lymphoma and germ cell tumours. It can be associated with severe toxicity, long-term complications and even death in extreme cases. There is a lack of evidence or consensus on how to prevent and monitor bleomycin toxicity. We surveyed 63 germ cell cancer physicians from 32 cancer centres across the UK to understand their approach to using bleomycin. Subsequent guideline development was based upon current practice, best available published evidence and expert consensus. We observed heterogeneity in practice in the following areas: monitoring; route of administration; contraindications to use; baseline and follow-up investigations performed, and advice given to patients. A best-practice clinical guideline for the use of bleomycin in the treatment of germ cell tumours has been developed and includes recommendations regarding baseline investigations, the use of pulmonary function tests, route of administration, monitoring and patient advice. It is likely that existing heterogeneity in clinical practice of bleomycin prescribing has significant economic, safety and patient experience implications. The development of an evidence-based consensus guideline was supported by 93% of survey participants and aims to address these issues and homogenise practice across the UK.
Subject(s)
Antibiotics, Antineoplastic/administration & dosage , Bleomycin/administration & dosage , Neoplasms, Germ Cell and Embryonal/drug therapy , Testicular Neoplasms/drug therapy , Antibiotics, Antineoplastic/adverse effects , Antibiotics, Antineoplastic/pharmacology , Bleomycin/adverse effects , Bleomycin/pharmacology , Clinical Trials as Topic , Consensus , Evidence-Based Medicine , Humans , Male , Neoplasms, Germ Cell and Embryonal/physiopathology , Respiratory Function Tests , Testicular Neoplasms/physiopathology , United KingdomABSTRACT
Objectives: This study aimed to investigate the anti-PD-1 inhibitor pembrolizumab as a potential agent for use in non-muscle-invasive bladder cancer (NMIBC) by conducting a Phase 1 safety run-in study to assess the safety and tolerability of intravesical pembrolizumab after transurethral resection of the bladder tumour (TURBT). Patients and methods: Eligible patients had recurrent NMIBC for which adjuvant treatment post TURBT was a reasonable treatment option, Eastern Cooperative Oncology Group Performance Status (ECOG PS) 0-1 and adequate end-organ function. Pembrolizumab was administered by intravesical instillation once weekly for a total of six doses. Intra-patient dose escalation was performed in three paired patient cohorts with doses starting at 50 mg and increasing through 100 mg to a maximum of 200 mg. Adverse events (AEs) were assessed using Common Terminology Criteria for Adverse Events (CTCAE) v4.03 with dose limiting toxicity (DLT) defined as a clinically significant, drug-related, Grade 4 haematological or Grade 3 or higher non-haematological toxicity occurring within 7 days of administration of the first treatment at a given dose for that patient. Results: Six patients were treated with no DLTs seen during dose escalation. Drug-related AEs were of low grade and included dysuria and fatigue. All patients completed six doses of treatment as planned. Pharmacokinetic and pharmacodynamic assays did not detect any pembrolizumab in the serum following repeated intravesical administration, and no changes in peripheral immune cell populations were observed. Conclusions: Administration of intravesical pembrolizumab was well tolerated and did not raise any safety concerns in patients with NMIBC following TURBT. There was no evidence of systemic absorption or systemic immune effects following intravesical administration. Further studies are required to assess whether intravesical administration has anti-tumour activity.
ABSTRACT
BACKGROUND: STAMPEDE previously reported adding upfront docetaxel improved overall survival for prostate cancer patients starting long-term androgen deprivation therapy. We report long-term results for non-metastatic patients using, as primary outcome, metastatic progression-free survival (mPFS), an externally demonstrated surrogate for overall survival. METHODS: Standard of care (SOC) was androgen deprivation therapy with or without radical prostate radiotherapy. A total of 460 SOC and 230 SOC plus docetaxel were randomly assigned 2:1. Standard survival methods and intention to treat were used. Treatment effect estimates were summarized from adjusted Cox regression models, switching to restricted mean survival time if non-proportional hazards. mPFS (new metastases, skeletal-related events, or prostate cancer death) had 70% power (α = 0.05) for a hazard ratio (HR) of 0.70. Secondary outcome measures included overall survival, failure-free survival (FFS), and progression-free survival (PFS: mPFS, locoregional progression). RESULTS: Median follow-up was 6.5 years with 142 mPFS events on SOC (3 year and 54% increases over previous report). There was no good evidence of an advantage to SOC plus docetaxel on mPFS (HR = 0.89, 95% confidence interval [CI] = 0.66 to 1.19; P = .43); with 5-year mPFS 82% (95% CI = 78% to 87%) SOC plus docetaxel vs 77% (95% CI = 73% to 81%) SOC. Secondary outcomes showed evidence SOC plus docetaxel improved FFS (HR = 0.70, 95% CI = 0.55 to 0.88; P = .002) and PFS (nonproportional P = .03, restricted mean survival time difference = 5.8 months, 95% CI = 0.5 to 11.2; P = .03) but no good evidence of overall survival benefit (125 SOC deaths; HR = 0.88, 95% CI = 0.64 to 1.21; P = .44). There was no evidence SOC plus docetaxel increased late toxicity: post 1 year, 29% SOC and 30% SOC plus docetaxel grade 3-5 toxicity. CONCLUSIONS: There is robust evidence that SOC plus docetaxel improved FFS and PFS (previously shown to increase quality-adjusted life-years), without excess late toxicity, which did not translate into benefit for longer-term outcomes. This may influence patient management in individual cases.
Subject(s)
Prostatic Neoplasms , Androgen Antagonists/therapeutic use , Androgens , Docetaxel/therapeutic use , Humans , Male , Prostate-Specific Antigen , Prostatic Neoplasms/drug therapyABSTRACT
Research conducted over the past two decades has shown the importance of the type 1 insulin-like growth factor receptor (IGF1R) in tumorigenesis, metastasis, and resistance to existing forms of cancer therapy. The IGF1R itself has only recently been accepted as a credible treatment target, however, perhaps reflecting the potential problems for drug design posed by normal tissue IGF1R expression, and close homology with the insulin receptor. Currently approximately 12 anti-IGF1R therapeutics are undergoing clinical evaluation, including blocking antibodies and tyrosine kinase inhibitors. This review will summarize the principal signaling pathways activated by IGF1R and the preclinical data that validated this receptor as a treatment target. We will review clinical progress in the testing of IGF1R inhibitory drug candidates, the relative benefits and potential toxicities of coinhibition of the insulin receptor, and the rationale for combining IGF1R blockade with other cancer treatments. An understanding of IGF1R signaling is important because it will guide the incorporation of appropriate molecular markers into clinical trial design. This will be key to the identification of patients most likely to benefit, and so will influence the ability of IGF1R inhibition to make the transition from experimental intervention to clinical therapy.
Subject(s)
Receptor, IGF Type 1/physiology , Animals , Antineoplastic Agents/therapeutic use , Humans , Neoplasms/drug therapy , Receptor, IGF Type 1/antagonists & inhibitors , Receptor, Insulin/physiology , Signal Transduction/drug effectsABSTRACT
More than a million men worldwide are diagnosed with prostate cancer every year. After androgen deprivation therapy (ADT), chemotherapy has been the only subsequent intervention to improve survival in the metastatic setting but has limitations for patients who may not tolerate its toxicity profile or are not candidates on the basis of comorbidities. Novel anti-androgens such as abiraterone acetate have shown promise for such patients. This review draws on clinical evidence and experience to identify abiraterone as a well-tolerated, effective alternative to docetaxel. In the castration-resistant setting, studies demonstrated a survival benefit over placebo, prompting further trials in the hormone-naïve population. More recently the STAMPEDE and LATITUDE studies suggest abiraterone has comparable survival outcomes to docetaxel in the castration-sensitive setting, with evidence in favour of its quality of life profile. Available comparisons with docetaxel are limited, but those available suggest they have comparable efficacy. However, the significant cost compared with docetaxel is a major barrier in resource-rationed healthcare settings. Overall, abiraterone is an effective alternative to chemotherapy for men with castration-sensitive prostate cancer, but this should be balanced with the significantly greater cost.
ABSTRACT
The outlook for patients with advanced renal cell cancer (RCC) has been improved by targeted agents including inhibitors of the PI3 kinase (PI3K)-AKT-mTOR axis, although treatment resistance is a major problem. Here, we aimed to understand how RCC cells acquire resistance to PI3K-mTOR inhibition. We used the RCC4 cell line to generate a model of in vitro resistance by continuous culture in PI3K-mTOR kinase inhibitor NVP-BEZ235 (BEZ235, Dactolisib). Resistant cells were cross-resistant to mTOR inhibitor AZD2014. Sensitivity was regained after 4 months drug withdrawal, and resistance was partially suppressed by HDAC inhibition, supporting an epigenetic mechanism. BEZ235-resistant cells up-regulated and/or activated numerous proteins including MET, ABL, Notch, IGF-1R, INSR and MEK/ERK. However, resistance was not reversed by inhibiting or depleting these pathways, suggesting that many induced changes were passengers not drivers of resistance. BEZ235 blocked phosphorylation of mTOR targets S6 and 4E-BP1 in parental cells, but 4E-BP1 remained phosphorylated in resistant cells, suggesting BEZ235-refractory mTORC1 activity. Consistent with this, resistant cells over-expressed mTORC1 component RAPTOR at the mRNA and protein level. Furthermore, BEZ235 resistance was suppressed by RAPTOR depletion, or allosteric mTORC1 inhibitor rapamycin. These data reveal that RAPTOR up-regulation contributes to PI3K-mTOR inhibitor resistance, and suggest that RAPTOR expression should be included in the pharmacodynamic assessment of mTOR kinase inhibitor trials.
Subject(s)
Carcinoma, Renal Cell/drug therapy , Kidney Neoplasms/drug therapy , Phosphoinositide-3 Kinase Inhibitors , Regulatory-Associated Protein of mTOR/metabolism , TOR Serine-Threonine Kinases/antagonists & inhibitors , Up-Regulation , Antineoplastic Agents/pharmacology , Antineoplastic Agents/therapeutic use , Benzamides , Carcinoma, Renal Cell/metabolism , Carcinoma, Renal Cell/pathology , Cell Line, Tumor , Drug Resistance, Neoplasm , Histone Deacetylase Inhibitors/pharmacology , Humans , Imidazoles/pharmacology , Imidazoles/therapeutic use , Kidney Neoplasms/metabolism , Kidney Neoplasms/pathology , Morpholines/therapeutic use , Pyrimidines , Quinolines/pharmacology , Quinolines/therapeutic use , Signal Transduction/drug effectsABSTRACT
BACKGROUND: Stage 1 seminoma is frequently cured by radical orchiectomy; however, the management strategies after this diagnosis vary in terms of the use of adjuvant treatment and the nature of the follow-up protocols. We analyzed stage 1 seminomas treated in the Thames Valley Cancer Network for outcomes to determine whether any factors are predictive of recurrence. We also studied relapses to determine the optimal follow-up schedule and protocol. MATERIALS AND METHODS: Data were obtained from centers within the Thames Valley Cancer Network for a 12-year period from 2004 to 2016. We identified 501 patients with stage 1 seminoma. RESULTS: Relapses occurred in 6.2% of the patients receiving adjuvant treatment and 6.1% of those who did not. The only statistically significant predictive factor identified for relapse was rete testis invasion, and the risk was greater when only stromal rete invasion was included, rather than pagetoid as well. A trend was seen toward an increased risk with increased tumor size, but the difference was not statistically significant. Recurrences developed within the first 2 years after surgery in nearly 75% of cases and were identified through surveillance computed tomography scans in 54.8% of the patients. All relapses were treated curatively. CONCLUSION: Active surveillance leads to excellent outcomes for stage 1 seminoma; however, adjuvant treatment should be reserved for those with high-risk disease. Follow-up schedules should include computed tomography imaging during the first 3 years, long-term measurement of tumor markers, and mechanisms for patients to be seen promptly should symptoms of tumor recurrence occur.
Subject(s)
Neoplasm Recurrence, Local/epidemiology , Seminoma/drug therapy , Testicular Neoplasms/surgery , Watchful Waiting/methods , Adult , Chemotherapy, Adjuvant , Humans , Male , Orchiectomy , Practice Guidelines as Topic , Prospective Studies , Radiotherapy, Adjuvant , Survival Analysis , Testicular Neoplasms/drug therapy , Tomography, X-Ray Computed , Tumor BurdenABSTRACT
Purpose Two previous single-arm trials have drawn conflicting conclusions regarding the activity of pazopanib in urothelial cancers after failure of platinum-based chemotherapy. Patients and Methods This randomized (1:1) open-label phase II trial compared the efficacy of pazopanib 800 mg orally with paclitaxel (80 mg/m2 days 1, 8, and 15 every 28 days) in the second-line setting. The primary end point was overall survival (OS). Results Between August 2012 and October 2014, 131 patients, out of 140 planned, were randomly assigned. The study was terminated early on the recommendation of the independent data monitoring committee because of futility. Final analysis after the preplanned number of deaths (n = 110) occurred after a median follow-up of 18 months. One hundred fifteen deaths had occurred at the final data extract presented here. Median OS was 8.0 months for paclitaxel (80% CI, 6.9 to 9.7 months) and 4.7 months for pazopanib (80% CI, 4.2 to 6.4 months). The hazard ratio (HR) adjusted for baseline stratification factors was 1.28 (80% CI, 0.99 to 1.67; one-sided P = .89). Median progression-free survival was 4.1 months for paclitaxel (80% CI, 3.0 to 5.6 months) and 3.1 months for pazopanib (80% CI, 2.7 to 4.6 months; HR, 1.09; 80% CI, 0.85 to 1.40; one-sided P = .67). Discontinuations for toxicity occurred in 7.8% and 23.1% for paclitaxel and pazopanib, respectively. Conclusion Pazopanib did not have greater efficacy than paclitaxel in the second-line treatment of urothelial cancers. There was a trend toward superior OS for paclitaxel.
Subject(s)
Paclitaxel/administration & dosage , Pyrimidines/administration & dosage , Sulfonamides/administration & dosage , Urologic Neoplasms/drug therapy , Administration, Oral , Aged , Antineoplastic Agents, Phytogenic/administration & dosage , Drug Administration Schedule , Female , Humans , Indazoles , Kaplan-Meier Estimate , Male , Middle Aged , Survival RateABSTRACT
Many localised, superficial bladder cancers can be effectively controlled. However, disease which has spread to nodes outside the pelvis or to distant organs is generally incurable and systemic therapies, rather than surgery, are appropriate. Combination chemotherapy based around established cytotoxic drugs such as cisplatin has proven benefit in palliating symptoms and prolonging survival in responsive patients with advanced disease. Combination chemotherapies which include newer cytotoxic drugs such as gemcitabine provide the potential for equivalent efficacy with less toxicity than established regimens. Between the extremes of superficial and advanced disease, muscle-invasive bladder cancers have traditionally been treated, with curative intent, by radical surgery or radiotherapy. However, newly published data suggest, for the first time, genuine survival benefits from peri-operative chemotherapy. This article reviews the evidence for cisplatin-based chemotherapy in advanced disease, assesses the potential benefits of newer cytotoxic drugs, discusses the latest evidence pertaining to peri-operative chemotherapy in muscle-invasive disease, and looks forward to potential new biological agents in the systemic therapy of bladder cancer.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Deoxycytidine/analogs & derivatives , Urinary Bladder Neoplasms/drug therapy , Antimetabolites, Antineoplastic/administration & dosage , Chemotherapy, Adjuvant , Cisplatin/administration & dosage , Clinical Trials as Topic , Deoxycytidine/administration & dosage , Genes, p53 , Genetic Therapy , Humans , Immunologic Factors/therapeutic use , Neoadjuvant Therapy , Phenotype , Treatment Outcome , Urinary Bladder Neoplasms/genetics , Urinary Bladder Neoplasms/pathology , Urinary Bladder Neoplasms/surgery , GemcitabineSubject(s)
Neoplasms, Germ Cell and Embryonal/epidemiology , Neoplasms, Multiple Primary/epidemiology , Neoplasms, Second Primary/epidemiology , Testicular Neoplasms/epidemiology , Adult , Age of Onset , Aged , Disease Management , Humans , Longitudinal Studies , Male , Middle Aged , Neoplasms, Germ Cell and Embryonal/pathology , Neoplasms, Multiple Primary/pathology , Neoplasms, Second Primary/pathology , Retrospective Studies , Tertiary Care Centers , Testicular Neoplasms/pathology , United Kingdom/epidemiology , Young AdultABSTRACT
BACKGROUND AND PURPOSE: IGF-1R depletion sensitizes prostate cancer cells to ionizing radiation and DNA-damaging cytotoxic drugs. This study investigated the hypothesis that IGF-1R regulates DNA double strand break (DSB) repair. METHODS: We tested effects of IGF-1R siRNA transfection on the repair of radiation-induced DSBs by immunoblotting and immunofluorescence for γH2AX, and pulsed-field gel electrophoresis. Homologous recombination (HR) was quantified by reporter assays, and cell cycle distribution by flow cytometry. RESULTS: We confirmed that IGF-1R depletion sensitized DU145 and PC3 prostate cancer cells to ionizing radiation. DU145 control transfectants resolved radiation-induced DSBs within 24 h, while IGF-1R depleted cells contained 30-40% unrepaired breaks at 24 h. IGF-1R depletion induced significant reduction in DSB repair by HR, although the magnitude of the repair defect suggests additional contributory factors. Radiation-induced G2-M arrest was attenuated by IGF-1R depletion, potentially suppressing cell cycle-dependent processes required for HR. In contrast, IGF-1R depletion induced only minor radiosensitization in LNCaP cells, and did not influence repair. Cell cycle profiles were similar to DU145, so were unlikely to account for differences in repair responses. CONCLUSIONS: These data indicate a role for IGF-1R in DSB repair, at least in part via HR, and support use of IGF-1R inhibitors with DNA damaging cancer treatments.
Subject(s)
DNA Breaks, Double-Stranded/radiation effects , DNA Repair/radiation effects , Prostatic Neoplasms/metabolism , Receptor, IGF Type 1/metabolism , Cell Cycle/radiation effects , Cell Line, Tumor , Electrophoresis, Gel, Pulsed-Field , Histones/metabolism , Homologous Recombination/radiation effects , Humans , Insulin Receptor Substrate Proteins/metabolism , Male , RNA, Small Interfering/metabolism , Radiation Dosage , Radiation Tolerance/physiology , Receptor, Insulin/metabolismABSTRACT
The type 1 insulin-like growth factor receptor (IGF-1R) is a transmembrane glycoprotein composed of two extracellular alpha subunits and two beta subunits with tyrosine kinase activity. The IGF-1R is frequently upregulated in cancers and signals from the cell surface to promote proliferation and cell survival. Recent attention has focused on the IGF-1R as a target for cancer treatment. Here, we report that the nuclei of human tumor cells contain IGF-1R, detectable using multiple antibodies to alpha- and beta-subunit domains. Cell-surface IGF-1R translocates to the nucleus following clathrin-mediated endocytosis, regulated by IGF levels. The IGF-1R is unusual among transmembrane receptors that undergo nuclear import, in that both alpha and beta subunits traffic to the nucleus. Nuclear IGF-1R is phosphorylated in response to ligand and undergoes IGF-induced interaction with chromatin, suggesting direct engagement in transcriptional regulation. The IGF dependence of these phenomena indicates a requirement for the receptor kinase, and indeed, IGF-1R nuclear import and chromatin binding can be blocked by a novel IGF-1R kinase inhibitor. Nuclear IGF-1R is detectable in primary renal cancer cells, formalin-fixed tumors, preinvasive lesions in the breast, and nonmalignant tissues characterized by a high proliferation rate. In clear cell renal cancer, nuclear IGF-1R is associated with adverse prognosis. Our findings suggest that IGF-1R nuclear import has biological significance, may contribute directly to IGF-1R function, and may influence the efficacy of IGF-1R inhibitory drugs.
Subject(s)
Cell Membrane/metabolism , Cell Nucleus/metabolism , Neoplasms/metabolism , Receptor, IGF Type 1/metabolism , 3T3 Cells , Animals , Breast Neoplasms/metabolism , Carcinoma, Renal Cell/metabolism , Cell Line, Tumor , Humans , Immunohistochemistry , Kidney Neoplasms/metabolism , Male , Mice , Prostatic Neoplasms/metabolism , Protein Structure, TertiaryABSTRACT
PURPOSE: Expression of the type 1 insulin-like growth factor receptor (IGF1R) confers adverse prognosis in clear cell renal cell cancer (CC-RCC). We recently showed that IGF1R expression is inhibited by the von Hippel-Lindau (VHL) tumor suppressor, and the IGF1R is up-regulated in CC-RCC, in which VHL is frequently inactivated. We tested the hypothesis that IGF1R up-regulation mediates resistance to cancer therapeutics, evaluating the effects of IGF1R depletion on sensitivity to cytotoxic drugs, which are ineffective in RCC, and the mammalian target of rapamycin (mTOR) inhibitor rapamycin, analogues of which have clinical activity in this tumor. EXPERIMENTAL DESIGN: This study used CC-RCC cells harboring mutant VHL, and isogenic cells expressing functional VHL. Cells were transfected with nonsilencing control small interfering RNA (siRNA), or with one of two different IGF1R siRNAs. The more potent siRNA was modified by 2'-O-methyl derivatization for in vivo administration. RESULTS: CC-RCC cells expressing mutant VHL and higher IGF1R were more chemoresistant than cells expressing functional VHL. IGF1R depletion induced apoptosis, blocked cell survival, and sensitized to 5-fluorouracil and etoposide. These effects were significantly greater in CC-RCC cells expressing mutant VHL, supporting the hypothesis that IGF1R up-regulation makes a major contribution to the chemoresistance associated with VHL loss. IGF1R depletion also enhanced sensitivity to mTOR inhibition, at least in part due to suppression of rapamycin-induced Akt activation. Administration of stabilized IGF1R siRNA was shown to sensitize CC-RCC xenografts to rapamycin in vivo. CONCLUSION: These data validate IGF1R as a therapeutic target in CC-RCC, and support the evaluation of IGF1R-inhibitory drugs in patients with renal cancer.