Helen Anderson

Phase I Clinical Trial of Weekly Combretastatin A4 Phosphate: Clinical and Pharmacokinetic Results

PURPOSE A phase I trial was performed with combretastatin A4 phosphate (CA4P), a novel tubulin-binding agent that has been shown to rapidly reduce blood flow in animal tumors. PATIENTS AND METHODS The drug was delivered by a 10-minute weekly infusion for 3 weeks followed by a week gap, with intrapatient dose escalation. Dose escalation was accomplished by doubling until grade 2 toxicity was seen. The starting dose was 5 mg/m2. RESULTS Thirty-four patients received 167 infusions. CA4P was rapidly converted to the active combretastatin A4 (CA4), which was further metabolized to the glucuronide. CA4 area under the curve (AUC) increased from 0.169 at 5 mg/m2 to 3.29 micromol * h/L at 114 mg/m2. The mean CA4 AUC in eight patients at 68 mg/m2 was 2.33 micromol * h/L compared with 5.8 micromol * h/L at 25 mg/kg (the lowest effective dose) in the mouse. The only toxicity that possibly was related to the drug dose up to 40 mg/m2 was tumor pain. Dose-limiting toxicity was reversible ataxia at 114 mg/m2, vasovagal syncope and motor neuropathy at 88 mg/m2, and fatal ischemia in previously irradiated bowel at 52 mg/m2. Other drug-related grade 2 or higher toxicities seen in more than one patient were pain, lymphopenia, fatigue, anemia, diarrhea, hypertension, hypotension, vomiting, visual disturbance, and dyspnea. One patient at 68 mg/m2 had improvement in liver metastases of adrenocortical carcinoma. CONCLUSION CA4P was well tolerated in 14 of 16 patients at 52 or 68 mg/m2; these are doses at which tumor blood flow reduction has been recorded.

Assessment of Pharmacodynamic Vascular Response in a Phase I Trial of Combretastatin A4 Phosphate

PURPOSE Clinical evaluation of novel agents that target tumor blood vessels requires pharmacodynamic end points that measure vascular damage. Positron emission tomography (PET) was used to measure the effects of the vascular targeting agent combretastatin A4 phosphate (CA4P) on tumor and normal tissue perfusion and blood volume. PATIENTS AND METHODS Patients with advanced solid tumors were enrolled onto part of a phase I, accelerated-titration, dose-escalation study. The effects of 5 to 114 mg/m2 CA4P on tumor, spleen, and kidney were investigated. Tissue perfusion was measured using oxygen-15 (15O)-labeled water and blood volume was measured using 15O-labeled carbon monoxide (C15O). Scans were performed immediately before, and 30 minutes and 24 hours after the first infusion of each dose level of CA4P. All statistical tests were two sided. RESULTS PET data were obtained for 13 patients with intrapatient dose escalation. Significant dose-dependent reductions were seen in tumor perfusion 30 minutes after CA4P administration (mean change, -49% at >or= 52 mg/m2; P =.0010). Significant reductions were also seen in tumor blood volume (mean change, -15% at >or= 52 mg/m2; P =.0070). Although by 24 hours there was tumor vascular recovery, for doses >or= 52 mg/m2 the reduction in perfusion remained significant (P =.013). Thirty minutes after CA4P administration borderline significant changes were seen in spleen perfusion (mean change, -35%; P =.018), spleen blood volume (mean change, -18%; P =.022), kidney perfusion (mean change, -6%; P =.026), and kidney blood volume (mean change, -6%; P =.014). No significant changes were seen at 24 hours in spleen or kidney. CONCLUSION CA4P produces rapid changes in the vasculature of human tumors that can be assessed using PET measurements of tumor perfusion.

Relationship between plasma estradiol levels and estrogen-responsive gene expression in estrogen receptor-positive breast cancer in postmenopausal women.

PURPOSE To determine whether plasma estradiol (E2) levels are related to gene expression in estrogen receptor (ER)-positive breast cancers in postmenopausal women. Materials and METHODS Genome-wide RNA profiles were obtained from pretreatment core-cut tumor biopsies from 104 postmenopausal patients with primary ER-positive breast cancer treated with neoadjuvant anastrozole. Pretreatment plasma E2 levels were determined by highly sensitive radioimmunoassay. Genes were identified for which expression was correlated with pretreatment plasma E2 levels. Validation was performed in an independent set of 73 ER-positive breast cancers. Results The expression of many known estrogen-responsive genes and gene sets was highly significantly associated with plasma E2 levels (eg, TFF1/pS2, GREB1, PDZK1 and PGR; P < .005). Plasma E2 explained 27% of the average expression of these four average estrogen-responsive genes (ie, AvERG; r = 0.51; P < .0001), and a standardized mean of plasma E2 levels and ER transcript levels explained 37% (r, 0.61). These observations were validated in an independent set of 73 ER-positive tumors. Exploratory analysis suggested that addition of the nuclear coregulators in a multivariable analysis with ER and E2 levels might additionally improve the relationship with the AvERG. Plasma E2 and the standardized mean of E2 and ER were both significantly correlated with 2-week Ki67, a surrogate marker of clinical outcome (r = -0.179; P = .05; and r = -0.389; P = .0005, respectively). CONCLUSION Plasma E2 levels are significantly associated with gene expression of ER-positive breast cancers and should be considered in future genomic studies of ER-positive breast cancer. The AvERG is a new experimental tool for the study of putative estrogenic stimuli of breast cancer.

Molecular Profiling of Aromatase Inhibitor–Treated Postmenopausal Breast Tumors Identifies Immune-Related Correlates of Resistance

Purpose: Estrogen withdrawal by treatment with aromatase inhibitors is the most effective form of endocrine therapy for postmenopausal estrogen receptor–positive (ER+) breast cancer. However, response to therapy varies markedly and understanding of the precise molecular effects of aromatase inhibitors and causes of resistance is limited. We aimed to identify in clinical breast cancer those genes and pathways most associated with resistance to aromatase inhibitors by examining the global transcriptional effects of AI treatment. Experimental Design: Baseline and 2-week posttreatment biopsies were obtained from 112 postmenopausal women with ER+ breast cancer receiving neoadjuvant anastrozole. Gene expression data were obtained from 81 baseline and 2-week paired samples. Pathway analysis identified (i) the most prevalent changes in expression and (ii) the pretreatment genes/pathways most related to poor antiproliferative response. Results: A total of 1,327 genes were differentially expressed after 2-week treatment (false discovery rate < 0.01). Proliferation-associated genes and classical estrogen-dependent genes were strongly downregulated whereas collagens and chemokines were upregulated. Pretreatment expression of an inflammatory signature correlated with antiproliferative response to anastrozole and this observation was validated in an independent study. Higher expression of immune-related genes such as SLAMF8 and TNF as well as lymphocytic infiltration were associated with poorer response (P < 0.001) and validated in an independent cohort. Conclusions: The molecular response to aromatase inhibitor treatment varies greatly between patients consistent with the variable clinical benefit from aromatase inhibitor treatment. Higher baseline expression of an inflammatory signature is associated with poor antiproliferative response and should be assessed further as a novel biomarker and potential target for aromatase inhibitor-treated patients. Clin Cancer Res; 19(10); 2775–86. ©2013 AACR.

A Gene Expression Signature from Human Breast Cancer Cells with Acquired Hormone Independence Identifies MYC as a Mediator of Antiestrogen Resistance

Purpose: Although most patients with estrogen receptor α (ER)-positive breast cancer initially respond to endocrine therapy, many ultimately develop resistance to antiestrogens. However, mechanisms of antiestrogen resistance and biomarkers predictive of such resistance are underdeveloped. Experimental Design: We adapted four ER+ human breast cancer cell lines to grow in an estrogen-depleted medium. A gene signature of estrogen independence was developed by comparing expression profiles of long-term estrogen-deprived (LTED) cells to their parental counterparts. We evaluated the ability of the LTED signature to predict tumor response to neoadjuvant therapy with an aromatase inhibitor and disease outcome following adjuvant tamoxifen. We utilized Gene Set Analysis (GSA) of LTED cell gene expression profiles and a loss-of-function approach to identify pathways causally associated with resistance to endocrine therapy. Results: The LTED gene expression signature was predictive of high tumor cell proliferation following neoadjuvant therapy with anastrozole and letrozole, each in different patient cohorts. This signature was also predictive of poor recurrence-free survival in two studies of patients treated with adjuvant tamoxifen. Bioinformatic interrogation of expression profiles in LTED cells revealed a signature of MYC activation. The MYC activation signature and high MYC protein levels were both predictive of poor outcome following tamoxifen therapy. Finally, knockdown of MYC inhibited LTED cell growth. Conclusions: A gene expression signature derived from ER+ breast cancer cells with acquired hormone independence predicted tumor response to aromatase inhibitors and associated with clinical markers of resistance to tamoxifen. Activation of the MYC pathway was associated with this resistance. Clin Cancer Res; 17(7); 2024–34. ©2011 AACR.

Endocrine Therapy, New Biologicals, and New Study Designs for Presurgical Studies in Breast Cancer

The preoperative setting is increasingly popular for the clinical investigation of hormonal agents and new biological drugs. The effectiveness of endocrine agents is well established for estrogen receptor-positive disease, and the emphasis in preoperative studies is on their combination with agents targeted at resistance mechanisms over 3 or more months. New agents are also being assessed for early evidence of clinical efficacy in shorter-term window-of-opportunity studies. The establishment of Ki67 as an intermediate marker of treatment benefit and of long-term outcome, with endocrine drugs, provides the opportunity for new trial designs with Ki67 as the primary endpoint. The PeriOperative Endocrine Therapy for Individualizing Care (POETIC) trial is randomizing (2:1) 4000 estrogen receptor-positive patients to 2 weeks presurgical treatment with a nonsteroidal aromatase inhibitor or no presurgical treatment. It provides a unique opportunity for detailed study of the determinants of response and resistance to estrogen deprivation as well as testing the role of presurgical therapy for improved biomarker-based estimates of prognosis.

Comparative validation of the SP6 antibody to Ki67 in breast cancer

Aim To compare SP6 and MIB1 antibodies for Ki67 staining in breast cancer. Background Immunohistochemical detection of Ki67 has been widely used to assess the proliferative fraction in breast cancer. Ki67 is used prognostically and is the primary end-point for some presurgical trials. MIB1 has been the preferred antibody, but SP6 has become available, with apparently improved performance. The importance of Ki67 led us to systematically compare SP6 with MIB1. Methods Two sets of tissue microarrays were used. These were constructed from formalin-fixed paraffin-embedded breast cancers: (i) 177 cancers with data on response to an aromatase inhibitor for advanced disease (cohort 1); (ii) 200 mainly oestrogen-receptor-positive cancers without response data (cohort 2). Twenty-eight pairs of core-cut biopsies taken before and after aromatase inhibitor treatment were also assessed (cohort 3). Stained sections were examined either visually or by using an image analysis system (Ariol). Results There was a strong correlation between the two antibodies in all cohorts of samples scored visually (cohort 1: n=161, r=0.93, p<0.0001; cohort 2: n=194, r=0.84, p<0.0001; cohort 3: n=54, r=0.89, p<0.0001). Correlation between visual and Ariol scores was markedly better with the SP6 antibody (r=0.71 and r=0.88 for MIB1 and SP6, respectively). Ki67 related similarly with time-to-treatment failure with the two antibodies (cohort 1). Changes in Ki67 values with the two antibodies after 2 weeks of aromatase inhibitor treatment also correlated strongly. Conclusions SP6 and MIB1 provide highly comparable measures of Ki67 that predict progression of advanced disease similarly. SP6 is substantially better suited than MIB1 to image analysis.

Predictors of response to aromatase inhibitors

Aromatase inhibitors are now considered to be part of the endocrine treatment for most hormone receptor-positive breast cancer in post-menopausal women for both early and advanced disease. Despite the impressive efficacy of these agents, up to 50% of treated patients exhibit de novo or intrinsic resistance to aromatase inhibitors and hence identification of response predictors is essential to allow treatment to be directed towards responsive populations and for alternative or additional therapies to be offered to resistant patients. Emerging data seem to suggest a role for the conventional tumour markers of oestrogen receptor and progesterone receptor as possible predictors of response but, particularly in the adjuvant setting, the extent to which these are useful has not been fully elucidated. Data from both the neo-adjuvant and advanced disease settings suggest that response to aromatase inhibitors does not appear to be adversely affected by HER-2 overexpression. Within neo-adjuvant aromatase inhibitor studies, the proliferation marker Ki67 has shown a significant correlation with relapse-free survival, suggesting a role in prediction for measurement of Ki67 and other dynamic markers of response. Analysis of multiple gene expression changes over a short treatment period may also have potential clinical utility for prediction of response.

Pan Canadian Rash Trial: A Randomized Phase III Trial Evaluating the Impact of a Prophylactic Skin Treatment Regimen on Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitor–Induced Skin Toxicities in Patients With Metastatic Lung Cancer

PURPOSE Erlotinib is an epidermal growth factor receptor inhibitor approved for patients with advanced non-small-cell lung cancer (NSCLC) whose epidermal growth factor receptor expression status is positive or unknown. Although it is efficacious, erlotinib can cause skin toxicity. This prospective, randomized phase III trial examined the effect of prophylactic treatment of erlotinib-induced skin rash. PATIENTS AND METHODS Patients receiving erlotinib in the second- or third-line setting for advanced NSCLC were randomly assigned to prophylactic minocycline (100 mg twice per day for 4 weeks), reactive treatment (after rash developed, per grade of rash), or no treatment unless severe (grade 3). Rash incidence and severity, time to maximal rash, time to resolution, and overall survival (OS) were compared among treatment groups. RESULTS In all, 150 patients were randomly assigned, 50 to each of three treatment arms. The incidence of skin toxicity was 84% regardless of treatment arm. Prophylactic treatment with minocycline significantly lengthened the time to the most severe grade of rash. Grade 3 rash was significantly higher in the no-treatment arm. OS was not significantly different among treatment arms, but patients receiving prophylactic or reactive treatments had a longer OS (7.6 and 8 months, respectively) than those who received no rash treatment (6 months). Rash was not self-limiting. CONCLUSION The incidence of all grades of rash did not differ statistically among the three arms, so the trial was negative. The incidence of grade 3 skin toxicities was reduced in patients who were treated with prophylactic minocycline or reactive treatment. Efficacy was not compromised. Prophylactic minocycline and reactive treatment are both acceptable options for the necessary treatment of erlotinib-induced rash in the second- or third-line setting of metastatic NSCLC.

Selection of Reference Genes for Normalization of qRT-PCR Data Derived From FFPE Breast Tumors

Gene expression analysis of formalin-fixed paraffin-embedded (FFPE) material by quantitative real-time polymerase chain reaction is a valuable tool for the retrospective analysis of clinical samples. The degraded nature of RNA from FFPE tissue can lead to variation in detection of gene expression between samples, hence, it is necessary to select reference genes that can reflect this variation. To identify suitable references for the normalization of target genes in FFPE breast tumors, expression of 10 potential references were measured in 10 endocrine therapy-naive, primary invasive breast tumors. The most stably expressed reference genes were identified with the use of the freely available algorithm geNorm. Using the geometric mean of MRPL19, TBP, and TFRC as a reference factor for FFPE tissue, there was a good correlation of ERα and HER2 measurements between FFPE and matched frozen tumors, indicating that this combination of reference genes successfully removed the effect of RNA degradation on quantitative real-time polymerase chain reaction analysis.