Acquired gene alterations in patients treated with ribociclib plus endocrine therapy or endocrine therapy alone using baseline and end-of-treatment circulating tumor DNA samples in the MONALEESA-2, -3, and -7 trials.

BACKGROUND: A prior pooled analysis of the MONALEESA-2, -3, and -7 trials identified baseline markers predictive of sensitivity or resistance to ribociclib plus endocrine therapy (ET). We report the results of an analysis of paired baseline and end-of-treatment (EOT) circulating tumor DNA (ctDNA) samples across the MONALEESA trials. PATIENTS AND METHODS: Paired baseline and EOT ctDNA samples from MONALEESA-2, -3, and -7 were sequenced using a targeted next-generation sequencing panel. Genes with an EOT alteration prevalence of >5% were included. A McNemar test was performed on paired samples and adjusted for multiple testing to control the false discovery rate. A Bayesian mixed-effects model was used to adjust for ctDNA fraction at both time points and for study differences. RESULTS: The analysis included 523 paired samples. At EOT, 21 genes had a >5% alteration prevalence. A trend for higher ctDNA fraction at EOT vs baseline (P=0.08) was observed. Prevalence of alterations was higher at EOT vs baseline in RB1, SPEN, TPR, PCDH15, and FGFR2 in the ribociclib arm; PBRM1 in the placebo arm; and ESR1 in both arms. The mixed-effects model demonstrated that the same trends for increased prevalence of these alterations at EOT were observed after adjusting for ctDNA fraction and that the increased rate of RB1 and SPEN alterations at EOT were specific to ribociclib plus ET. Analysis of ESR1 indicated a similar increase at EOT in both arms. The most common acquired ESR1 mutations at EOT included Y537C/N/S/D, D538G, E380Q, and L536H/R/P/LC. The prevalence of PIK3CA hotspot mutations at baseline and EOT was similar. CONCLUSIONS: This analysis identified acquired gene alterations in patients with HR+/HER2- advanced breast cancer treated with ribociclib plus ET or placebo plus ET. These data may support further studies on acquired resistance mechanisms and inform future systemic interventions in the post-CDK4/6 inhibitor setting.

Pooled ctDNA analysis of MONALEESA phase III advanced breast cancer trials.

BACKGROUND: The phase III MONALEESA trials tested the efficacy and safety of the cyclin-dependent kinase (CDK)4/6 inhibitor ribociclib with different endocrine therapy partners as first- or second-line treatment of hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer (ABC). Using the largest pooled biomarker dataset of the CDK4/6 inhibitor ribociclib in ABC to date, we identified potential biomarkers of response to ribociclib. PATIENTS AND METHODS: Baseline circulating tumour DNA from patients in the MONALEESA trials was assessed using next-generation sequencing. An analysis of correlation between gene alteration status and progression-free survival (PFS) was carried out to identify potential biomarkers of response to ribociclib. RESULTS: Multiple frequently altered genes were identified. Alterations in ERBB2, FAT3, FRS2, MDM2, SFRP1, and ZNF217 were associated with a greater PFS benefit with ribociclib versus placebo. Patients with high tumour mutational burden (TMB) and with ANO1, CDKN2A/2B/2C, and RB1 alterations exhibited decreased sensitivity to ribociclib versus placebo. CONCLUSIONS: Although exploratory, these results provide insight into alterations associated with the improved response to ribociclib treatment and may inform treatment sequencing in patients with actionable alterations following progression on CDK4/6 inhibitors. Validation of potential biomarkers identified here and development of prospective trials testing their clinical utility are warranted. GOV IDENTIFIERS: NCT01958021, NCT02422615, NCT02278120.

Updated overall survival from the MONALEESA-3 trial in postmenopausal women with HR+/HER2- advanced breast cancer receiving first-line ribociclib plus fulvestrant.

BACKGROUND: The phase III MONALEESA-3 trial included first- (1L) and second-line (2L) patients and demonstrated a significant overall survival (OS) benefit for ribociclib + fulvestrant in patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative (HR+/HER2-) advanced breast cancer (ABC) in the final protocol-specified and exploratory (longer follow-up) OS analyses. At the time of these analyses, the full OS benefit of 1L ribociclib was not completely characterized because the median OS (mOS) was not reached. As CDK4/6 inhibitor (CDK4/6i) + endocrine therapy (ET) is now a preferred option for 1L HR+/HER2- ABC, we report an exploratory analysis (median follow-up, 70.8 months; 14.5 months longer than the prior analysis) to fully elucidate the OS benefit in the MONALEESA-3 1L population. METHODS: Postmenopausal patients with HR+/HER2- ABC were randomized 2:1 to 1L/2L fulvestrant + ribociclib or placebo. OS in 1L patients (de novo disease or relapse > 12 months from completion of [neo]adjuvant ET) was assessed by Cox proportional hazards model and Kaplan-Meier methods. Progression-free survival 2 (PFS2) and chemotherapy-free survival (CFS) were analyzed. MONALEESA-3 is registered with ClinicalTrials.gov (NCT02422615). RESULTS: At data cutoff (January 12, 2022; median follow-up time, 70.8 months), mOS was 67.6 versus 51.8 months with 1L ribociclib versus placebo (hazard ratio (HR) 0.67; 95% CI 0.50-0.90); 16.5% and 8.6% of ribociclib and placebo patients, respectively, were still receiving treatment. PFS2 (HR 0.64) and CFS (HR 0.62) favored ribociclib versus placebo. Among those who discontinued treatment, 16.7% and 35.0% on ribociclib or placebo, respectively, received a subsequent CDK4/6i. No new safety signals were observed. CONCLUSIONS: This analysis of MONALEESA-3 reports the longest mOS thus far (67.6 months) for 1L patients in a phase III ABC trial. These results in a 1L population show that the OS benefit of ribociclib was maintained through extended follow-up, further supporting its use in HR+/HER2- ABC.

Results of TRIO-15, a multicenter, open-label, phase II study of the efficacy and safety of ganitumab in patients with recurrent platinum-sensitive ovarian cancer.

BACKGROUND: IGF signaling has been implicated in the pathogenesis and progression of ovarian carcinoma (OC). Single agent activity and safety of ganitumab (AMG 479), a fully human monoclonal antibody against IGF1R that blocks binding of IGF1 and IGF2, were evaluated in patients with platinum-sensitive recurrent OC. METHODS: Patients with CA125 progression (GCIG criteria) or measurable disease per RECIST following primary platinum-based therapy received 18 mg/kg of ganitumab q3w. The primary endpoint was objective response rate (ORR) assessed per RECIST 1.1 by an independent radiology review committee (IRC) and/or GCIG CA125 criteria. Secondary endpoints included clinical benefit rate (CBR), progression free survival (PFS) and overall survival (OS). RESULTS: 61 pts. were accrued. Objective responses were seen in 5/61 patients (ORR 8.2%, 95% CI, 3.1-18.8) with 1 partial response (PR) by RECIST and 2 complete responses (CR) as well as 2 PR by CA125 criteria. CBR was 80.3% (95% CI, 67.8-89.0%). The median PFS according to RECIST by IRC was 2.1 months (95% CI, 2.0-3.1). The median PFS per RECIST IRC and/or CA125 was 2.0 months (95% CI, 1.8-2.2). The median OS was 21 months (95% CI, 19.5-NA). The most common overall adverse events were fatigue (36.1%) and hypertension (34.4%). Grade 1/2 hyperglycemia occurred in 30.4% of patients. Hypertension (11.5%) and hypersensitivity (8.2%) were the most frequent grade 3 adverse events. CONCLUSIONS: IGF1R inhibition with ganitumab was well-tolerated, however, our results do not support further study of ganitumab as a single agent in unselected OC patients.

Tucatinib versus placebo added to trastuzumab and capecitabine for patients with pretreated HER2+ metastatic breast cancer with and without brain metastases (HER2CLIMB): final overall survival analysis.

BACKGROUND: In the primary analysis of the HER2CLIMB trial, tucatinib added to trastuzumab and capecitabine significantly improved overall survival (OS) and progression-free survival (PFS) in patients with human epidermal growth factor receptor 2 positive (HER2+) metastatic breast cancer. We report efficacy and safety outcomes, including the final OS and safety outcomes from follow-up in HER2CLIMB. PATIENTS AND METHODS: HER2CLIMB is a randomized, double-blind, placebo-controlled trial in patients with locally advanced or metastatic HER2+ breast cancer, including patients with brain metastases. Patients were randomized 2 : 1 to receive tucatinib or placebo, in combination with trastuzumab and capecitabine. After the primary analysis (median follow-up of 14 months), the protocol was amended to allow for unblinding sites to treatment assignment and cross-over from the placebo combination to the tucatinib combination. Protocol prespecified descriptive analyses of OS, PFS (by investigator assessment), and safety were carried out at ∼2 years from the last patient randomized. RESULTS: Six hundred and twelve patients enrolled in the HER2CLIMB trial. At a median OS follow-up of 29.6 months, median duration of OS was 24.7 months for the tucatinib combination group versus 19.2 months for the placebo combination group [hazard ratio (HR) for death: 0.73, 95% confidence interval (CI): 0.59-0.90, P = 0.004] and OS at 2 years was 51% and 40%, respectively. HRs for OS across prespecified subgroups were consistent with the HR for the overall study population. Median duration of PFS was 7.6 months for the tucatinib combination group versus 4.9 months for the placebo combination group (HR for progression or death: 0.57, 95% CI: 0.47-0.70, P < 0.00001) and PFS at 1 year was 29% and 14%, respectively. The tucatinib combination was well tolerated with a low rate of discontinuation due to adverse events. CONCLUSIONS: With additional follow-up, the tucatinib combination provided a clinically meaningful survival benefit for patients with HER2+ metastatic breast cancer.

Results of TRIO-14, a phase II, multicenter, randomized, placebo-controlled trial of carboplatin-paclitaxel versus carboplatin-paclitaxel-ganitumab in newly diagnosed epithelial ovarian cancer.

PURPOSE: Insulin-like growth factor (IGF) signaling is implicated in pathogenesis and chemotherapy resistance of epithelial ovarian cancer (EOC). We explored efficacy and safety of adding ganitumab, a monoclonal antibody targeting IGF-1R, to carboplatin/paclitaxel (CP) chemotherapy in patients with primary EOC. DESIGN: Patients were randomly assigned to receive CP/ganitumab (18 mg/kg q3w) or CP/placebo for 6 cycles followed by 6 cycles of single agent ganitumab/placebo maintenance therapy as front-line therapy. Primary endpoint was progression free survival. Secondary endpoints were time to progression and overall survival. Pretreatment samples were prospectively collected for retrospective biomarker analyses. RESULTS: 170 patients enrolled. 165 patients assessable for toxicity. Median PFS was 15.7 months with CP/ganitumab and 16.7 months with CP/placebo (HR 1.23; 95% CI 0.82-1.83, P = 0.313). All grade neutropenia (84.1% vs 71.4%), thrombocytopenia (75.3% vs 57.1%) and hyperglycemia (15.9% vs 2.6%) were more common in the ganitumab group compared to the placebo group. Ganitumab/placebo related serious adverse events were reported in 26.1% of the patients with ganitumab and in 6.5% with placebo. Non-progression related fatal events were more common with ganitumab (5 versus 2 patients). The ganitumab group experienced more dose delays which resulted in lower relative dose intensity of chemotherapy in the experimental group. In an exploratory model IGFBP2 expression was predictive of ganitumab response (treatment interaction; PFS, P = 0.03; OS, P = 0.01). CONCLUSION: Addition of ganitumab to CP chemotherapy in primary EOC did not improve PFS. Our results do not support further study of ganitumab in unselected EOC patients.

Ribociclib plus fulvestrant for postmenopausal women with hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer in the phase III randomized MONALEESA-3 trial: updated overall survival.

BACKGROUND: Ribociclib plus fulvestrant demonstrated significant progression-free survival (PFS) and overall survival (OS) benefits in patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative (HR+/HER2-) advanced breast cancer (ABC). Here we present a new landmark in survival follow-up for a phase III cyclin-dependent kinases 4 and 6 inhibitor clinical trial in patients with ABC (median, 56.3 months). PATIENTS AND METHODS: This phase III, randomized, double-blind, placebo-controlled trial was conducted at 174 sites (30 countries). Patients were men and postmenopausal women (age ≥18 years) with histologically/cytologically confirmed HR+/HER2- ABC. Patients could have received ≤1 line of endocrine therapy (ET) but no chemotherapy for ABC. Patients, assigned 2:1, were stratified by the presence/absence of liver/lung metastases and previous ET. Patients received intramuscular fulvestrant (500 mg, day 1 of each 28-day cycle plus day 15 of cycle 1) with oral ribociclib (600 mg/day, 3 weeks on, 1 week off) or placebo. Efficacy analyses were by intention to treat. Safety was assessed in patients receiving ≥1 dose study treatment. OS was a secondary endpoint. MONALEESA-3 is registered with ClinicalTrials.gov (NCT02422615; no longer enrolling). RESULTS: Between 18 June 2015 and 10 June 2016, 726 patients were randomly assigned (484, ribociclib; 242, placebo). At data cut-off (30 October 2020), median OS (mOS) was 53.7 months (ribociclib) versus 41.5 months (placebo) [hazard ratio (HR), 0.73; 95% confidence interval (CI) 0.59-0.90]. Subgroup analyses were consistent with overall population. In the first-line setting, most patients in the ribociclib arm (∼60%) lived longer than median follow-up; mOS was 51.8 months in the placebo arm (HR, 0.64; 95% CI 0.46-0.88). In the second-line setting, mOS was 39.7 months (ribociclib) versus 33.7 months (placebo) (HR, 0.78; 95% CI 0.59-1.04). No apparent drug-drug interaction between ribociclib and fulvestrant or new safety signals were observed. CONCLUSIONS: This analysis reported extended OS follow-up in MONALEESA-3. mOS was ∼12 months longer in patients with HR+/HER2- ABC treated with ribociclib plus fulvestrant compared with fulvestrant monotherapy.

Palbociclib plus letrozole as first-line therapy in estrogen receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer with extended follow-up.

PURPOSE: In the initial PALOMA-2 (NCT01740427) analysis with median follow-up of 23 months, palbociclib plus letrozole significantly prolonged progression-free survival (PFS) in women with estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC) [hazard ratio (HR) 0.58; P < 0.001]. Herein, we report results overall and by subgroups with extended follow-up. METHODS: In this double-blind, phase 3 study, post-menopausal women with ER+/HER2- ABC who had not received prior systemic therapy for their advanced disease were randomized 2:1 to palbociclib-letrozole or placebo-letrozole. Endpoints include investigator-assessed PFS (primary), safety, and patient-reported outcomes (PROs). RESULTS: After a median follow-up of approximately 38 months, median PFS was 27.6 months for palbociclib-letrozole (n = 444) and 14.5 months for placebo-letrozole (n = 222) (HR 0.563; 1-sided P < 0.0001). All subgroups benefited from palbociclib treatment. The improvement of PFS with palbociclib-letrozole was maintained in the next 2 subsequent lines of therapy and delayed the use of chemotherapy (40.4 vs. 29.9 months for palbociclib-letrozole vs. placebo-letrozole). Safety data were consistent with the known profile. Patients' quality of life was maintained. CONCLUSIONS: With approximately 15 months of additional follow-up, palbociclib plus letrozole continued to demonstrate improved PFS compared with placebo plus letrozole in the overall population and across all patient subgroups, while the safety profile remained favorable and quality of life was maintained. These data confirm that palbociclib-letrozole should be considered the standard of care for first-line therapy in patients with ER+/HER2- ABC, including those with low disease burden or long disease-free interval. Sponsored by Pfizer; ClinicalTrials.gov: NCT01740427.

Impact of palbociclib plus letrozole on patient-reported health-related quality of life: results from the PALOMA-2 trial.

Background: Patient-reported outcomes are integral in benefit-risk assessments of new treatment regimens. The PALOMA-2 study provides the largest body of evidence for patient-reported health-related quality of life (QOL) for patients with metastatic breast cancer (MBC) receiving first-line endocrine-based therapy (palbociclib plus letrozole and letrozole alone). Patients and methods: Treatment-naïve postmenopausal women with estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2-negative (HER2-) MBC were randomized 2 : 1 to palbociclib plus letrozole (n = 444) or placebo plus letrozole (n = 222). Patient-reported outcomes were assessed at baseline, day 1 of cycles 2 and 3, and day 1 of every other cycle from cycle 5 using the Functional Assessment of Cancer Therapy (FACT)-Breast and EuroQOL 5 dimensions (EQ-5D) questionnaires. Results: As of 26 February 2016, the median duration of follow-up was 23 months. Baseline scores were comparable between the two treatment arms. No significant between-arm differences were observed in change from baseline in FACT-Breast Total, FACT-General Total, or EQ-5D scores. Significantly greater improvement in pain scores was observed in the palbociclib plus letrozole arm (-0.256 versus -0.098; P = 0.0183). In both arms, deterioration of FACT-Breast Total score was significantly delayed in patients without progression versus those with progression and patients with partial or complete response versus those without. No significant difference was observed in FACT-Breast and EQ-5D index scores in patients with and without neutropenia. Conclusions: Overall, women with MBC receiving first-line endocrine therapy have a good QOL. The addition of palbociclib to letrozole maintains health-related QOL and improves pain scores in treatment-naïve postmenopausal patients with ER+/HER2- MBC compared with letrozole alone. Significantly greater delay in deterioration of health-related QOL was observed in patients without progression versus those who progressed and in patients with an objective response versus non-responders. ClinicalTrials.gov: NCT01740427 (https://clinicaltrials.gov/ct2/show/NCT01740427).

Progression-free survival as surrogate end point for overall survival in clinical trials of HER2-targeted agents in HER2-positive metastatic breast cancer.

BACKGROUND: The gold standard end point in randomized clinical trials in metastatic breast cancer (MBC) is overall survival (OS). Although therapeutics have been approved based on progression-free survival (PFS), its use as a primary end point is controversial. We aimed to assess to what extent PFS may be used as a surrogate for OS in randomized trials of anti-HER2 agents in HER2+ MBC. METHODS: Eligible trials accrued HER2+ MBC patients in 1992-2008. A correlation approach was used: at the individual level, to estimate the association between investigator-assessed PFS and OS using a bivariate model and at the trial level, to estimate the association between treatment effects on PFS and OS. Correlation values close to 1.0 would indicate strong surrogacy. RESULTS: We identified 2545 eligible patients in 13 randomized trials testing trastuzumab or lapatinib. We collected individual patient data from 1963 patients and retained 1839 patients from 9 trials for analysis (7 first-line trials). During follow-up, 1072 deaths and 1462 progression or deaths occurred. The median survival time was 22 months [95% confidence interval (CI) 21-23 months] and the median PFS was 5.7 months (95% CI 5.5-6.1 months). At the individual level, the Spearman correlation was equal to ρ = 0.67 (95% CI 0.66-0.67) corresponding to a squared correlation value of 0.45. At the trial level, the squared correlation between treatment effects (log hazard ratios) on PFS and OS was provided by R(2) = 0.51 (95% CI 0.22-0.81). CONCLUSIONS: In trials of HER2-targeted agents in HER2+ MBC, PFS moderately correlates with OS at the individual level and treatment effects on PFS correlate moderately with those on overall mortality, providing only modest support for considering PFS as a surrogate. PFS does not completely substitute for OS in this setting.

Impact of palbociclib plus letrozole on pain severity and pain interference with daily activities in patients with estrogen receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer as first-line treatment.

Background Palbociclib is a recently approved drug for use in combination with letrozole as initial endocrine-based therapy for the treatment of postmenopausal women with advanced estrogen receptor-positive/human epidermal growth factor receptor 2-negative (ER+/HER2-) breast cancer. This report assesses the impact of palbociclib in combination with letrozole versus letrozole alone on patient-reported outcomes of pain. Methods Palbociclib was evaluated in an open-label, randomized, phase II study (PALOMA-1/TRIO-18) among postmenopausal women with advanced ER+/HER2- breast cancer who had not received prior systemic treatment for their advanced disease. Patients received continuous oral letrozole 2.5 mg daily alone or the same letrozole dose and schedule plus oral palbociclib 125 mg, given once daily for 3 weeks followed by 1 week off over repeated 28-day cycles. The primary study endpoint was investigator-assessed progression-free survival in the intent-to-treat population, and these results have recently been published (Finn et al., Lancet Oncol 2015;16:25-35). One of the key secondary endpoints was the evaluation of pain, as measured using the Brief Pain Inventory (BPI) patient-reported outcome tool. The BPI was administered at baseline and on day 1 of every cycle thereafter until disease progression and/or treatment discontinuation. Clinical trial registration This study is registered with ClinicalTrials.gov (NCT00721409). Results There were no statistically significant differences in Pain Severity or Pain Interference scores of the BPI between the two treatment groups for the overall population or among those with any bone disease at baseline. A limitation of the study is that results were not adjusted for the concomitant use of opioids or other medications used to control pain. Conclusions The addition of palbociclib to letrozole was associated with increased efficacy without negatively impacting pain severity or pain interference with daily activities.

Statistical controversies in clinical research: statistical significance-too much of a good thing .

The use and interpretation of P values is a matter of debate in applied research. We argue that P values are useful as a pragmatic guide to interpret the results of a clinical trial, not as a strict binary boundary that separates real treatment effects from lack thereof. We illustrate our point using the result of BOLERO-1, a randomized, double-blind trial evaluating the efficacy and safety of adding everolimus to trastuzumab and paclitaxel as first-line therapy for HER2+ advanced breast cancer. In this trial, the benefit of everolimus was seen only in the predefined subset of patients with hormone receptor-negative breast cancer at baseline (progression-free survival hazard ratio = 0.66, P = 0.0049). A strict interpretation of this finding, based on complex 'alpha splitting' rules to assess statistical significance, led to the conclusion that the benefit of everolimus was not statistically significant either overall or in the subset. We contend that this interpretation does not do justice to the data, and we argue that the benefit of everolimus in hormone receptor-negative breast cancer is both statistically compelling and clinically relevant.

KRAS mutational subtype and copy number predict in vitro response of human pancreatic cancer cell lines to MEK inhibition.

BACKGROUND: To study the molecular mechanism regulating sensitivity to MEK inhibition in pancreatic cancer cell lines. METHODS: A growth inhibition assay determined sensitivity to MEK162 in a panel of 29 pancreatic cancer cell lines. For the same panel, KRAS mutational status and copy-number variation (CNV) was determine using PCR, array CGH and FISH. Two sensitive and two resistant cell lines were further interrogated for difference in baseline and MEK162-induced gene expression, as well as signal transduction using microarray and western blotting. Cell cycle and apoptosis analysis was measured by flow cytometry. RESULTS: We report a strong correlation between both specific KRAS mutational subtype and CNV, and sensitivity to MEK inhibition. Cell lines with a KRAS (V12) mutation and KRAS gains or loss (n=7) are ∼10 times more resistant than those having neither a KRAS (V12) mutation nor KRAS CNV (n=14). Significant differences in baseline and MEK162-induced gene expression exist between the sensitive and resistant lines, especially in genes involved in RAS, EGF receptor and PI3K pathways. This was further supported by difference in signal transduction. MEK 162 blocked ERK1/2, as well as inhibited PI3K and S6 and increased p27KIP1 levels in the sensitive lines. CONCLUSIONS: Given the potency of MEK162, it may be a promising new therapy for patients with pancreatic cancer and KRAS mutational subtypes, and CNV may serve as important biomarkers for selecting patients that benefit from MEK-targeting based on these preclinical data.

FOXA1 represses the molecular phenotype of basal breast cancer cells.

Breast cancer is a heterogeneous disease that comprises multiple subtypes. Luminal subtype tumors confer a more favorable patient prognosis, which is, in part, attributed to estrogen receptor (ER)-α positivity and antihormone responsiveness. Expression of the forkhead box transcription factor, FOXA1, similarly correlates with the luminal subtype and patient survival, but is also present in a subset of ER-negative tumors. FOXA1 is also consistently expressed in luminal breast cancer cell lines even in the absence of ER. In contrast, breast cancer cell lines representing the basal subtype do not express FOXA1. To delineate an ER-independent role for FOXA1 in maintaining the luminal phenotype, and hence a more favorable prognosis, we performed expression microarray analyses on FOXA1-positive and ER-positive (MCF7, T47D), or FOXA1-positive and ER-negative (MDA-MB-453, SKBR3) luminal cell lines in the presence or absence of transient FOXA1 silencing. This resulted in three FOXA1 transcriptomes: (1) a luminal signature (consistent across cell lines), (2) an ER-positive signature (restricted to MCF7 and T47D) and (3) an ER-negative signature (restricted to MDA-MB-453 and SKBR3). Gene set enrichment analyses revealed FOXA1 silencing causes a partial transcriptome shift from luminal to basal gene expression signatures. FOXA1 binds to a subset of both luminal and basal genes within luminal breast cancer cells, and loss of FOXA1 increases enhancer RNA transcription for a representative basal gene (CD58). These data suggest FOXA1 directly represses a subset of basal signature genes. Functionally, FOXA1 silencing increases migration and invasion of luminal cancer cells, both of which are characteristics of basal subtype cells. We conclude FOXA1 controls plasticity between basal and luminal breast cancer cells, not only by inducing luminal genes but also by repressing the basal phenotype, and thus aggressiveness. Although it has been proposed that FOXA1-targeting agents may be useful for treating luminal tumors, these data suggest that this approach may promote transitions toward more aggressive cancers.

Inhibition of IGF1R activity enhances response to trastuzumab in HER-2-positive breast cancer cells.

BACKGROUND: although trastuzumab has improved the prognosis for HER-2-positive breast cancer patients, not all HER-2-positive breast tumours respond to trastuzumab treatment and those that initially respond frequently develop resistance. Insulin-like growth factor-1 receptor (IGF1R) signalling has been previously implicated in trastuzumab resistance. We tested IGF1R inhibition to determine if dual targeting of HER-2 and IGF1R improves response in cell line models of acquired trastuzumab resistance. MATERIALS AND METHODS: HER-2, IGF1R, phospho-HER-2, and phospho-IGF1R levels were measured by enzyme-linked immunosorbent assays in parental and trastuzumab-resistant SKBR3 and BT474 cells. IGF1R signalling was targeted in these cells using both small interfering RNA (siRNA) and the tyrosine kinase inhibitor, NVP-AEW541. RESULTS: IGF1R levels were significantly increased in the trastuzumab-resistant model, SKBR3/Tr, compared with the parental SKBR3 cell line. In both the SKBR3/Tr and BT474/Tr cell lines, inhibition of IGF1R expression with siRNA or inhibition of tyrosine kinase activity by NVP-AEW541 significantly increased response to trastuzumab. The dual targeting approach also improved response in the parental SKBR3 cells but not in the BT474 parental cells. CONCLUSIONS: our results confirm that IGF1R inhibition improves response to trastuzumab in HER-2-positive breast cancer cells and suggest that dual targeting of IGF1R and HER-2 may improve response in HER-2-positive tumours.

Activity of the multikinase inhibitor dasatinib against ovarian cancer cells.

BACKGROUND: Here, we explore the therapeutic potential of dasatinib, a small-molecule inhibitor that targets multiple cytosolic and membrane-bound tyrosine kinases, including members of the Src kinase family, EphA2, and focal adhesion kinase for the treatment of ovarian cancer. METHODS: We examined the effects of dasatinib on proliferation, invasion, apoptosis, cell-cycle arrest, and kinase activity using a panel of 34 established human ovarian cancer cell lines. Molecular markers for response prediction were studied using gene expression profiling. Multiple drug effect/combination index (CI) isobologram analysis was used to study the interactions with chemotherapeutic drugs. RESULTS: Concentration-dependent anti-proliferative effects of dasatinib were seen in all ovarian cancer cell lines tested, but varied significantly between individual cell lines with up to a 3 log-fold difference in the IC(50) values (IC(50) range: 0.001-11.3 micromol l(-1)). Dasatinib significantly inhibited invasion, and induced cell apoptosis, but less cell-cycle arrest. At a wide range of clinically achievable drug concentrations, additive and synergistic interactions were observed for dasatinib plus carboplatin (mean CI values, range: 0.73-1.11) or paclitaxel (mean CI values, range: 0.76-1.05). In this study, 24 out of 34 (71%) representative ovarian cancer cell lines were highly sensitive to dasatinib, compared with only 8 out of 39 (21%) representative breast cancer cell lines previously reported. Cell lines with high expression of Yes, Lyn, Eph2A, caveolin-1 and 2, moesin, annexin-1, and uPA were particularly sensitive to dasatinib. CONCLUSIONS: These data provide a clear biological rationale to test dasatinib as a single agent or in combination with chemotherapy in patients with ovarian cancer.

In vitro metabolism of the specific endothelin-A receptor antagonist ZD4054 and clinical drug interactions between ZD4054 and rifampicin or itraconazole in healthy male volunteers.

ZD4054 is an oral specific endothelin-A receptor antagonist in development for the treatment of hormone-resistant prostate cancer. Both renal and metabolic processes contribute to its overall clearance. Two preclinical in vitro studies investigated the metabolism of ZD4054 using human liver microsomes, individual cytochrome P450 (CYP) isozymes, and flavin-containing monooxygenase isoforms. Two Phase I open-label crossover volunteer studies subsequently investigated in vivo drug interactions between ZD4054 and the CYP450 inducer rifampicin or CYP3A4 inhibitor itraconazole. The most abundant metabolite produced in in vitro incubations accounted for 12.8% of radioactivity after ZD4054 was incubated with CYP3A4. No significant flavin-containing monooxygenase metabolism of ZD4054 was observed. In the in vivo studies, rifampicin co-administration reduced the area under the concentration-time curve and maximum plasma concentration of ZD4054 by 68% and 29%, respectively, whilst co-administration with itraconazole was associated with an increase in ZD4054 area under the curve of approximately 28%. While co-administration of CYP450 inducers might be associated with reduced efficacy of ZD4054, dose reduction is unlikely to be required with concomitant administration of CYP3A4 inhibitors.

Activity of lapatinib a novel HER2 and EGFR dual kinase inhibitor in human endometrial cancer cells.

In this study, we explore the therapeutic potential of lapatinib a selective inhibitor of both the EGFR and HER2 tyrosine kinases for the treatment of endometrial cancer. The effect of lapatinib on tumour cell growth and receptor activation was studied in a panel of human endometrial cancer cell lines. Candidate molecular markers predicting sensitivity were assessed by baseline gene expression profiling, ELISA, and western blot analyses. Multiple drug effect/combination index (CI) isobologram analysis was used to study the interactions between chemotherapeutic drugs and lapatinib. Concentration-dependent anti-proliferative effects of lapatinib were seen in all endometrial cancer cell lines tested, but varied significantly between individual cell lines (IC(50) range: 0.052-10.9 micromol). HER2 overexpression or increased expression of EGFR was significantly associated with in vitro sensitivity (P=0.024 or 0.011, respectively). Lapatinib exerts growth inhibition in a PTEN-independent manner. Sensitive cell lines also exhibited increased expression of EGFR ligands or HER3. In contrast, lapatinib-resistant cell lines exhibited high androgen receptor (AR) levels or epithelial-to-mesenchymal transition (post-EMT) features. In endometrial cancer cells, at a wide range of clinically achievable drug concentrations, additive and synergistic interactions were observed for lapatinib plus carboplatin, paclitaxel, docetaxel, and doxorubicin. These observations provide a clear biologic rational to test lapatinib as a single agent or in combination with chemotherapy in endometrial cancer with HER2 overexpression. Expression of EGFR, its ligands, HER3, AR, and post-EMT markers warrant further evaluation to help define patients with HER2-nonoverexpressing endometrial cancer most likely to benefit from lapatinib.