Combined targeting of mTOR and AKT is an effective strategy for basal-like breast cancer in patient-derived xenograft models

Basal-like breast cancer is an aggressive disease for which targeted therapies are lacking. Recent studies showed that basal-like breast cancer is frequently associated with an increased activity of the phosphatidylinositol 3-kinase (PI3K) pathway, which is critical for cell growth, survival, and angiogenesis. To investigate the therapeutic potential of PI3K pathway inhibition in the treatment of basal-like breast cancer, we evaluated the antitumor effect of the mTOR inhibitor MK-8669 and AKT inhibitor MK-2206 in WU-BC4 and WU-BC5, two patient-derived xenograft models of basal-like breast cancer. Both models showed high levels of AKT phosphorylation and loss of PTEN expression. We observed a synergistic effect of MK-8669 and MK-2206 on tumor growth and cell proliferation in vivo. In addition, MK-8669 and MK-2206 inhibited angiogenesis as determined by CD31 immunohistochemistry. Biomarker studies indicated that treatment with MK-2206 inhibited AKT activation induced by MK-8669. To evaluate the effect of loss of PTEN on tumor cell sensitivity to PI3K pathway inhibition, we knocked down PTEN in WU-BC3, a basal-like breast cancer cell line with intact PTEN. Compared with control (GFP) knockdown, PTEN knockdown led to a more dramatic reduction in cell proliferation and tumor growth inhibition in response to MK-8669 and MK-2206 both in vitro and in vivo. Furthermore, a synergistic effect of these two agents on tumor volume was observed in WU-BC3 with PTEN knockdown. Our results provide a preclinical rationale for future clinical investigation of this combination in basal-like breast cancer with loss of PTEN.

A phase I trial of the IGF-1R antibody Cixutumumab in combination with temsirolimus in patients with metastatic breast cancer

The mammalian target of rapamycin (mTOR) plays a critical role in promoting tumor cell growth and is frequently activated in breast cancer. In preclinical studies, the antitumor activity of mTOR inhibitors is attenuated by feedback up-regulation of AKT mediated in part by Insulin-like growth factor type 1 receptor (IGF-1R). We designed a phase I trial to determine the maximum-tolerated dose (MTD) and pharmacodynamic effects of the IGF-1R antibody Cixutumumab in combination with temsirolimus in patients with metastatic breast cancer refractory to standard therapies. A 3 + 3 Phase I design was chosen. Temsirolimus and Cixutumumab were administered intravenously on days 1, 8, 15, and 22 of a 4-week cycle. Of the 26 patients enrolled, four did not complete cycle 1 because of disease progression (n = 3) or comorbid condition (n = 1) and were replaced. The MTD was determined from the remaining 22 patients, aged 34-72 (median 48) years. Most patients (86 %) had estrogen receptor positive cancer. The median number of prior chemotherapy regimens for metastatic disease was 3. The MTD was determined to be Cixutumumab 4 mg/kg and temsirolimus 15 mg weekly. Dose-limiting toxicities (DLTs) included mucositis, neutropenia, and thrombocytopenia. Other adverse events included grade 1/2 fatigue, anemia, and hyperglycemia. No objective responses were observed, but four patients experienced stable disease that lasted for at least 4 months. Compared with baseline, there was a significant increase in the serum levels of IGF-1 (p < 0.001) and IGFBP-3 (p = 0.019) on day 2. Compared with day 2, there were significant increases in the serum levels of IGF-1 (p < 0.001), IGF-2 (p = 0.001), and IGFBP-3 (p = 0.019) on day 8. A phase II study in women with metastatic breast cancer is ongoing.

Abstract LB-265: Patient-derived xenografts from advanced luminal-type breast cancer: insights into endocrine therapy resistance

Deeper understanding the mechanisms by which luminal-type breast cancer develops resistance to endocrine therapy and development of novel strategies to treat these patients requires model systems recapitulate human breast cancer as accurately as possible. An increasing body of work suggests patient derived xenografts (PDX) may represent an informative model for development of novel therapeutics. We therefore established seven xenograft tumor lines from late-stage breast cancer patients with estrogen positive (ER+) disease. To date five ER+ PDX lines have been tested for responses to estradiol treatment in overiectomized NOD/SCID mice. Three showed estradiol independent-growth, one estrogen-stimulated growth and in one estradiol-induced a regression. These patterns mimicked the clinical phenotypes of each patient, tracking survival and responses to serial endocrine treatments. To define new mechanisms for resistance, whole genome DNA sequencing, RNA sequencing and Reverse Phase Protein Assay analysis was conducted. These studies identified an ESR1/YAP1 balanced translocation in a PDX model and tumor of origin showing low levels of ER, paradoxical high level expression form luminal genes and extreme ET resistance. The ESR1 YAP1 fusion maintained the N terminal DNA binding motif of ESR1, but the hormone binding and AF2 motifs were replaced with the C terminal transactivation domain of YAP1. Expression ESR1 YAP1 in ER+ breast cancer models down-regulated ER and induced estrogen independent growth. PDX endocrine phenotypes parallel tumor of origin responses to endocrine therapy and revel novel mechanism for endocrine therapy resistance.

Citation Format: Matthew J. Ellis, Shunqiang Li, Dong Shen, Li Ding, Robert Crowder, Jeiya Shao, Rodrigo Goncalves, Yu Tao, Jingqin Luo, Aleix Prat, Wenbin Liu, Ana Maria Gonzalez-Angulo, Shuying Liu, Joshua F. McMichael, Chris Miller, Dave Larson, Robert S. Fulton, Tom Mooney, Jeremy Hoog, Li Lin, Therese Giuntoli, Caroline Bumb, Crystal Cooper, Rebecca Aft, Robert T. Kitchens, Stephen N. Johnson, Chanpheng Phommaly, Megha Shiyam Kavuri, Katherine DeSchryver, Austin Lin, YiYu Dong, Cynthia X. Ma, Timothy Pluard, Michael Naughton, Ron Bose, Rama Suresh, Reida G. McDowell, Loren Michel, Richard Wilson, Shaomeng Wang, Christopher Maher, Gordon B. Mills, Charles Perou, Elaine R. Mardis. Patient-derived xenografts from advanced luminal-type breast cancer: insights into endocrine therapy resistance. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-265. doi:10.1158/1538-7445.AM2013-LB-265

Racial differences in outcomes of triple-negative breast cancer

African American (AA) women have a higher incidence of triple-negative breast cancer (TNBC: negative for the expression of estrogen receptor, progesterone receptor, and HER2 gene amplification) than Caucasian (CA) women, explaining in part their higher breast cancer mortality. However, there have been inconsistent data in the literature regarding survival outcomes of TNBC in AA versus CA women. We performed a retrospective chart review on 493 patients with TNBC first seen at the Washington University Breast Oncology Clinic (WUBOC) between January 2006 and December 2010. Analysis was done on 490 women (30 % AA) for whom follow-up data was available. The median age at diagnosis was 53 (23-98) years and follow-up time was 27.2 months. There was no significant difference between AA and CA women in the age of diagnosis, median time from abnormal imaging to breast biopsy and from biopsy diagnosis to surgery, duration of follow-up, tumor stage, grade, and frequency of receiving neoadjuvant or adjuvant chemotherapy and pathologic complete response rate to neoadjuvant chemotherapy. There was no difference in disease free survival (DFS) and overall survival (OS) between AA and CA groups by either univariate or multivariate analysis that included age, race, and stage. The hazard ratio for AA women was 1.19 (CI 0.80-1.78, p = 0.39) and 0.91 (CI 0.62-1.35, p = 0.64) for OS and DFS, respectively. Among the 158 patients who developed recurrence or presented with stage IV disease (AA: n = 36, CA: n = 122), no racial differences in OS were observed. We conclude that race did not significantly affect the clinical presentation and outcome of TNBC in this single center study where patients received similar therapy and follow-up.

Activating HER2 mutations in HER2 gene amplification negative breast cancer

Data from 8 breast cancer genome-sequencing projects identified 25 patients with HER2 somatic mutations in cancers lacking HER2 gene amplification. To determine the phenotype of these mutations, we functionally characterized 13 HER2 mutations using in vitro kinase assays, protein structure analysis, cell culture, and xenograft experiments. Seven of these mutations are activating mutations, including G309A, D769H, D769Y, V777L, P780ins, V842I, and R896C. HER2 in-frame deletion 755-759, which is homologous to EGF receptor (EGFR) exon 19 in-frame deletions, had a neomorphic phenotype with increased phosphorylation of EGFR or HER3. L755S produced lapatinib resistance, but was not an activating mutation in our experimental systems. All of these mutations were sensitive to the irreversible kinase inhibitor, neratinib. These findings show that HER2 somatic mutation is an alternative mechanism to activate HER2 in breast cancer and they validate HER2 somatic mutations as drug targets for breast cancer treatment.

SIGNIFICANCE

We show that the majority of HER2 somatic mutations in breast cancer patients are activating mutations that likely drive tumorigenesis. Several patients had mutations that are resistant to the reversible HER2 inhibitor lapatinib, but are sensitive to the irreversible HER2 inhibitor, neratinib. Our results suggest that patients with HER2 mutation–positive breast cancers could benefit from existing HER2-targeted drugs.

A phase II study of UCN-01 in combination with irinotecan in patients with metastatic triple negative breast cancer

Mutations in TP53 lead to a defective G1 checkpoint and the dependence on checkpoint kinase 1 (Chk1) for G2 or S phase arrest in response to DNA damage. In preclinical studies, Chk1 inhibition resulted in enhanced cytotoxicity of several chemotherapeutic agents. The high frequency of TP53 mutations in triple negative breast cancer (TNBC: negative for estrogen receptor, progesterone receptor, and HER2) make Chk1 an attractive therapeutic target. UCN-01, a non-selective Chk1 inhibitor, combined with irinotecan demonstrated activity in advanced TNBC in our Phase I study. The goal of this trial was to further evaluate this treatment in women with TNBC. Patients with metastatic TNBC previously treated with anthracyclines and taxanes received irinotecan (100–125 mg/m² IV days 1, 8, 15, 22) and UCN-01 (70 mg/m² IV day 2, 35 mg/m² day 23 and subsequent doses) every 42-day cycle. Peripheral blood mononuclear cells (PBMC) and tumor specimens were collected. Twenty five patients were enrolled. The overall response (complete response (CR) + partial response (PR)) rate was 4 %. The clinical benefit rate (CR + PR + stable disease ≥6 months) was 12 %. Since UCN-01 inhibits PDK1, phosphorylated ribosomal protein S6 (pS6) in PBMC was assessed. Although reduced 24 h post UCN-01, pS6 levels rose to baseline by day 8, indicating loss of UCN-01 bioavailability. Immunostains of γH2AX and pChk1^S296 on serial tumor biopsies from four patients demonstrated an induction of DNA damage and Chk1 activation following irinotecan. However, Chk1 inhibition by UCN-01 was not observed in all tumors. Most tumors were basal-like (69 %), and carried mutations in TP53 (53 %). Median overall survival in patients with TP53 mutant tumors was poor compared to wild type (5.5 vs. 20.3 months, p = 0.004). This regimen had limited activity in TNBC. Inconsistent Chk1 inhibition was likely due to the pharmacokinetics of UCN-01. TP53 mutations were associated with a poor prognosis in metastatic TNBC.

Endocrine resistance in breast cancer: molecular pathways and rational development of targeted therapies

Endocrine resistance presents a major challenge in the management of estrogen receptor (ER)-positive breast cancer and is an area under intense investigation. Although the underlying mechanism is still poorly understood, many studies point towards the 'cross-talk' between ER and growth factor receptor signaling pathways as the key in the development of estrogen-independent growth in breast cancer. This review aims to provide the reader our current understanding of various molecular pathways that mediate endocrine resistance and that are being evaluated as therapeutic targets for ER-positive breast cancer. While most of the agents that target these pathways have only been tested in Phase I or small Phase II trials, some have shown encouraging results. A critical issue that remains is the development of research strategies and clinical trials that take into account the molecular heterogeneity of ER-positive breast cancer.

TBCRC 001: randomized phase II study of cetuximab in combination with carboplatin in stage IV triple-negative breast cancer

PURPOSE

Epidermal growth factor receptor (EGFR) is a targetable receptor frequently overexpressed in basal-like breast cancer, which comprises most triple-negative breast cancers (TNBCs), the only subtype without established targeted therapy.

PATIENTS AND METHODS

In this randomized phase II trial, patients with metastatic TNBC received anti-EGFR antibody cetuximab (400 mg/m(2) load then 250 mg/m(2) per week intravenously [IV]) alone, with carboplatin (area under the curve of 2, once per week IV) added after progression or as concomitant therapy from the beginning. Response rate (RR) was the primary end point; others included time to progression (TTP), overall survival (OS), and toxicity. Embedded correlative studies included molecular subtyping on archival tissue. Fresh tumor tissue before and after 7 to 14 days of therapy was used for microarray analyses exploring EGFR pathway activity and inhibition.

RESULTS

In 102 patients with TNBC, RRs were 6% (two of 31) to cetuximab and 16% (four of 25) to cetuximab plus carboplatin after progression. RR to those treated from the beginning with cetuximab plus carboplatin was 17% (12 of 71); 31% of patients responded or had prolonged disease stabilization. The cetuximab plus carboplatin regimen was well tolerated, but both TTP and OS were short at 2.1 months (95% CI, 1.8 to 5.5 months) and 10.4 months (95% CI, 7.7 to 13.1 months), respectively. Of 73 patients with archival tissue for analysis, 74% had basal-like molecular subtype. Sixteen patients had tumor biopsies before and 1 week after therapy; genomic patterns of the EGFR pathway showed activation in 13 and inhibition by therapy in five.

CONCLUSION

Despite strong preclinical data, combination cetuximab plus carboplatin in metastatic TNBC produced responses in fewer than 20% of patients. EGFR pathway analysis showed that most TNBCs involved activation. However, cetuximab blocked expression of the EGFR pathway in only a minority, suggesting that most had alternate mechanisms for pathway activation.

Clinical and correlative science results in a phase II study of UCN-01in combination with irinotecan in recurrent triple-negative breast cancer (TNBC)

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Background: Chk1 inhibitors enhance chemotherapy efficacy by inducing “mitotic catastrophe” in p53 deficient TNBC preclinical models. Irinotecan (I) combined with UCN-01, a nonselective Chk1 inhibitor, showed promising activity in TNBC in our phase I study. The primary objective of the phase II trial was to determine the efficacy and toxicity. Correlatives included assessing tumor molecular subtype, TP53, PTEN and pathways targeted by UCN-01. Methods: Pts with measurable, metastatic (met) TNBC, prior anthracycline (A) and taxane (T), received I (100-125 mg/m2 IV on days (d) 1, 8, 15, 22) and UCN-01 (70 mg/m2 IV on d2 and 35 mg/m2 on d23 and later doses) on a 42-d cycle (C). Archival tumors and serial peripheral blood mononuclear cells (PBMC) and optional tumor biopsies were collected. Results: Twenty five pts were enrolled. All had prior A and T. The median no. of prior regimens for met disease was 3 (range 1-4). Toxicities included neutropenia, diarrhea, nausea, vomiting, and hyperglycemia. Best responses included 1 PR, 8 SD (range 2.3-8.6 mos) for a clinical benefit rate (CR+PR+SD>6 mos) of 3/25 (12%), 95% CI (3, 31%). The median PFS and OS were 2.3 and 11.3 mos, respectively. pS6 was examined since UCN-01 inhibits PDK1. pS6 was reduced in PBMC 24h post UCN-01, but close to baseline by d8. Immunostain of cleaved caspase 3 (CC3), pHistone H3 (pHH3), γH2AX, and pS6 were done on serial biopsies from 4 pts with adequate biopsy materials. In all cases, pS6 was reduced 24h post UCN-01. Results for other markers were variable. One case with TP53 deletion showed an induction of CC3, with an increase in pHH3 and γH2AX, suggesting abrogation of cell cycle arrest and enhanced DNA damage. Among 15 with sufficient specimen for analysis, most were basal-like (basal 10, basal/HER2-E 1, HER2-E 2, Luminal B 2) by PAM50, low in PTEN level (11) and carried mutations in TP53 (8). Median OS was 5.5 (95% CI: 2, 11.3) mos in TP53 mutant and 20.3 (95% CI: 2.9, - ) mos in wild type populations (p=0.004). Conclusions: This regimen had limited activity in TNBC. Despite the long half-life, drug activity is not detectable by d8 based on PBMC analysis. Our data indicates that future trials in TNBC should consider p53 status.

A phase I study of BKM120, a novel oral selective phosphatidylinositol-3-kinase (PI3K) inhibitor, in combination with fulvestrant in postmenopausal women with estrogen receptor positive metastatic breast cancer

TPS664

Background: PI3K pathway activation plays a crucial role in mediating endocrine therapy resistance in estrogen receptor positive (ER+) breast cancer. We have shown previously that BKM120 in combination with fulvestrant induced synergistic apoptotic cell death in long-term estrogen deprived ER+ breast cancer (LTED) cell line models, supporting the clinical investigation of this combination in ER+ breast cancer. Methods: The study is composed of the dose escalation cohort (phase IA) and the expansion cohort (phase IB). In phase IA, a standard 3+3 phase I design is employed to determine the maximum tolerated dose (MTD) of the combination of BKM120 and fulvestrant in patients (pts) with ER+ metastatic breast cancer (MBC). In phase IB, an additional 10 pts will be enrolled at the MTD to further examine the toxicity profile and preliminary efficacy of this combination. Steady state concentrations of BKM120 will be analyzed. Postmenopausal women with ER+ MBC and measurable disease per RECIST are eligible. Pts who are currently taking fulvestrant without disease progression are eligible. There is no restriction on the number of prior lines of systemic therapy for metastatic disease in phase IA but < 3 lines is required in phase IB. Treatment consists of fulvestrant 500 mg IM administered monthly on day (d) 1 of each 28-d cycle, following the loading dose of 500 mg on d1 and d15, and BKM120 orally daily on d1-28 of each cycle. The starting dose level (DL) is DL1 (Table). Correlative studies include assessing PI3K pathway abnormalities (loss of PTEN and PIK3CA mutation) on archival tumor specimen, and treatment induced inhibition of PI3K pathway activity (pAKT, pS6, Cyclin D1, subcellular localization of FOXO3a, phosphoproteomics), tumor cell proliferation (Ki67) and apoptosis (cleaved caspase 3 or TUNEL staining) on tumor biopsies collected at baseline and cycle 2 day 1 in consented patients. Enrollment to DL1 is complete and the study is currently enrolling pts to DL2. [Table: see text]

A phase I trial of the IGF-1R antibody IMC-A12 in combination with temsirolimus in patients with metastatic breast cancer

534

Background: mTOR plays a critical role in promoting tumor cell growth. In preclinical studies, the anti-tumor activity of mTOR inhibitors is attenuated by feedback up-regulation of AKT mediated by IGF-1R. We designed a phase I trial to determine the maximum-tolerated dose (MTD), dose-limiting toxicities (DLT) and pharmacodynamic effects of the IGF-1R antibody IMC-A12 in combination with temsirolimus (tem) in patients (pts) with metastatic breast cancer (MBC) where mTOR is frequently activated. Methods: A 3+3 phase I design was chosen. Tem and IMC-A12 were administered IV days (d) 1, 8, 15, and 22 of a 4-week cycle in pts with MBC refractory to standard therapies. Tumor response was evaluated by RECIST. Adverse events (AE) were reported using CTC v3.0. Serum IGF 1 and C-peptide levels on d2 (24h post infusion) and d8 prior to drug infusion were compared to baseline (BL) using paired t-test. Results: Of 26 pts enrolled, 4 did not complete cycle 1 due to progression (3) or co-morbid condition (1). MTD was determined from remaining 22 pts aged 34-72 (median 48) years with ECOG PS 0 (55%) or 1 (45%). 86% had ER+ cancer. Median number of regimens for MBC was 4. Two DLTs at the starting DL (DL 1) necessitated dose de-escalation of tem to 20mg (DL-1), then to 15 mg (DL-2) which was tolerable (Table). Subsequent dose escalation of IMC-A12 led to DLTs in 0 of 6 in DL-2A and 2 of 3 pts in DL-2B. The MTD was defined as DL-2A. Other AEs included gr 1/2 fatigue, neutropenia, anemia, and hyperglycemia. No CR or PR, but 4 SD lasting ≥ 4 months were observed. At DL-2, -2A and -2B, serum IGF 1 levels were significantly elevated on d2 (p <0.002) and d8 compared to BL (p <0.001), but C-peptide levels were not found to differ from BL. Conclusions: The MTD for the combination of IMC-A12 and tem in pts with MBC is lower than that observed for single agents alone. A phase II study is ongoing in MBC. The study is supported in part by ASCO CDA, Komen Craft to CXM, N01-CM62205 and N01-CM-2011-00071. [Table: see text]

Racial differences in outcomes of triple-negative breast cancer

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Background: The incidence and mortality of breast cancer can differ significantly among racial and ethnic groups. African American (AA) women have a lower incidence of breast cancer, but higher mortality compared to other racial groups. Triple negative breast cancer (TNBC: negative for the expression of estrogen receptor, progesterone receptor and HER2), which is an aggressive type of breast cancer, occurs more frequently in AA women. The few studies addressing whether racial differences exist in the outcomes of patients with TNBC have yielded inconsistent results. Methods: The Washington University Medical Oncology Database captures the clinical information for all new patients (pts) seen at the Breast Oncology Clinic. Most of these pts reside in the St. Louis metropolitan area. Using this database, we performed a retrospective analysis to examine the association of race with the clinical presentation and outcome of TNBC in this geographically defined patient population. Results: Between May 2006 and March 2011, 506 pts with TNBC were entered in the database. Analysis was done on 499 patients for whom follow up data is available. The median follow up (F/U) time was 24.5 months and the median age at diagnosis was 53 (24 to 98) years. Thirty percent of pts were AA. Only 5% presented with stage IV at diagnosis and the majority of tumors (86%) were high grade. Neoadjuvant chemotherapy was administered in 151 pts, 22% of whom achieved a pathologic complete response (pCR). There was no significant difference between races in the age of diagnosis, F/U time, tumor stage, grade, frequency of receiving neo/adjuvant chemotherapy and pCR rate to neoadjuvant chemotherapy. There was no difference in disease free survival (DFS) and overall survival (OS) between AA and other racial groups by either univariate or multivariate analysis that took into account tumor stage, grade, patient age and menopausal status. The HR for OS was 1.154 (CI 0.772 – 1.725, p value 0.4860) and for DFS it was 0.947 (CI 0.650 – 1.380, p value 0.7764) in AA compared to other races. In the 92 pts who recurred, there was no racial difference in time from recurrence to death. Conclusions: Race does not significantly affect the clinical presentation or outcome of TNBC in the St. Louis metropolitan area.

ABT-888 (veliparib) in combination with carboplatin in patients with stage IV BRCA-associated breast cancer. A California Cancer Consortium Trial

1010

Background: Platinum and PARP inhibitors have both shown activity in BRCA-associated breast cancer (BC) patients (pts). We have conducted a phase I trial of carboplatin (Carb) and velapirib [V], a PARP inhibitor, to define dose limiting toxicities [(DLT) during cycle (C) 1] and the maximum tolerated dose (MTD). Methods: BRCA 1 or 2 carriers with stage IV BC were eligible. Carb starting at an AUC of 6 was given IV every 21 days (length of planned C) and V was administered orally, BID at dose levels (L) L1 through L5 (highest L planned). Results: 22 pts (21 eligible/evaluable, 20 with measurable BC) carrying BRCA1 (10) or BRCA2 (11), or both (1) mutations were accrued. Median age: 45 years, (32-65); 68% of BCs were ER+, and 10% were HER2+. In the table below are the schema, incidence of DLTs, and # of Cs on study. Toxicities: At L1, grade ¾ DLTs with C 1 were seen in 2/6 evaluable pts (1 pt w/grade 3 hyponatremia, pleural effusion, and dehydration, and 1pt w/grade 4 thrombocytopenia [PLT]), leading to deescalation of carb (AUC 5) for pts treated at Ls 2-5. At L2, 1 of 6 pts had grade 4 PLT. There were no DLTs at Ls 3 and L4. L5 is currently being expanded to 6 pts (3 currently enrolled, 1 pt with grade 4 granulocytopenia (Gr) and grade PLT reached DLT). Non-DLT dose delays mostly due ≥ grade 2 Gr or PLT were needed at 60%, 53%, 53%, and 43% of Cs in pts treated on Ls 1-4. Response: In 12 eligible pts treated at Ls 1 and 2, 2 complete and 6 partial responders (67%) and a clinical benefit (CB) of 75% were seen. All pts at Ls 3-5 are still being treated, and in pts treated at Ls 3 and 4, 2 unconfirmed PRs, and 4 cases of stable disease were seen, with L5 too early to assess. Conclusions: The combination of Carb at an AUC of 5 and daily V at doses 150 to 200 mg BID is feasible and the MTD is being defined. In preliminary analysis, response and CB rates are better than expected with the individual agents alone, providing justification to proceed with a planned phase II randomized single agent versus combination trial. [Table: see text]

Abstract IA3: PI3K inhibitors in ER+ breast cancer: Next steps

Gain and loss of function mutations in the PI3 kinase pathway are extremely common in breast cancer and can be seen in all five intrinsic subtypes (Luminal A, Luminal B, HER2+, Basal-like and Claudin Low). However there is a subtype-selective spectrum of activation events including gain of kinase mutations/amplifications (e.g. PIK3CA, HER2 and AKT1) and loss of negative regulators (e.g.PTEN, INPP4B and PIK3R 1). These lesions must be matched to a large number of agents in development that target PI3K, AKT and mTOR. These agents have variable specificities, toxicities, pharmacokinetics and administration routes which affect the development of combinations with standard therapies and also with each other. In keeping with very broad clinical opportunities, positive findings in preclinical models in both luminal and basal-like breast cancer will be presented. Ongoing clinical trial designs will also be discussed and biomarker approaches for patient selection and stratification will be considered.

Abstract 2861: Inhibition of mTOR and AKT as a potential strategy for the treatment of basal-like breast cancer

Basal-like breast cancer is an aggressive disease, for which effective targeted therapies are lacking. The frequent loss of phosphatase and tensin homolog (PTEN) and aberrant activation of phosphatidylinositol 3-kinase (PI3K)-AKT-mTOR pathway in basal-like breast cancer make it an attractive therapeutic strategy to target AKT and mTOR. To evaluate the effect of PTEN loss on tumor cell sensitivity to mTOR inhibition, we performed PTEN knockdown experiment in vitro using a basal-like breast cancer cell line WU-BC3, which was derived from a patient with triple negative breast cancer. A more dramatic reduction in cell proliferation was observed in WU-BC3 siPTEN compared to that in WU-BC3 siControl following 7 days of treatment with the mTOR inhibitor MK-8669 (p&lt;0.001). We then tested MK-8669 and MK-2206 (an allosteric, selective pan-AKT inhibitor), either alone or in combination, in 2 Human Tumor in Mouse (HIM) models of basal-like breast cancer, WU-BC4 and WU-BC5, that are deficient in PTEN expression in vivo. In both models, MK-8669 alone significantly inhibited tumor growth (p&lt;0.001). However, the combination of MK-8669 and MK-2206 was more effective than either MK-8669 (p&lt;0.05) or MK-2206 (p&lt;0.01) alone. Biomarker studies indicated that the combination therapy resulted in a more dramatic inhibition of tumor cell proliferation (as assessed by Ki67) and angiogenesis (as assessed by CD31 staining) than single agents alone in both models. In addition, treatment with MK-2206 abolished the MK-8669-induced AKT activation in vivo, suggesting the inhibition of the feedback loop between mTOR and AKT being a potential underlying mechanism for the enhanced anti-tumor effect observed with the combination therapy. Our results provide a preclinical rationale for future clinical investigation of this combination in basal-like breast cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2861. doi:1538-7445.AM2012-2861

Targeting Chk1 in p53-deficient triple-negative breast cancer is therapeutically beneficial in human-in-mouse tumor models

Patients with triple-negative breast cancer (TNBC) - defined by lack of estrogen receptor and progesterone receptor expression as well as lack of human epidermal growth factor receptor 2 (HER2) amplification - have a poor prognosis. There is a need for targeted therapies to treat this condition. TNBCs frequently harbor mutations in TP53, resulting in loss of the G1 checkpoint and reliance on checkpoint kinase 1 (Chk1) to arrest cells in response to DNA damage. Previous studies have shown that inhibition of Chk1 in a p53-deficient background results in apoptosis [corrected] in response to DNA damage. We therefore tested whether inhibition of Chk1 could potentiate the cytotoxicity of the DNA damaging agent irinotecan in TNBC using xenotransplant tumor models. Tumor specimens from patients with TNBC were engrafted into humanized mammary fat pads of immunodeficient mice to create 3 independent human-in-mouse TNBC lines: 1 WT (WU-BC3) and 2 mutant for TP53 (WU-BC4 and WU-BC5). These lines were tested for their response to irinotecan and a Chk1 inhibitor (either UCN-01 or AZD7762), either as single agents or in combination. The combination therapy induced checkpoint bypass and apoptosis in WU-BC4 and WU-BC5, but not WU-BC3, tumors. Moreover, combination therapy inhibited tumor growth and prolonged survival of mice bearing the WU-BC4 line, but not the WU-BC3 line. In addition, knockdown of p53 sensitized WU-BC3 tumors to the combination therapy. These results demonstrate that p53 is a major determinant of how TNBCs respond to therapies that combine DNA damage with Chk1 inhibition.

Molecular profiling of triple negative breast cancer

Advances in high-throughput technology and bioinformatics have made it possible to analyze tumors in an unbiased manner at the genomic level. These techniques aim to produce novel prognostic and predictive biomarkers, and most importantly, mechanistic insights that can be translated into ground-breaking therapeutic hypotheses. Genome-wide analysis is particularly relevant to the study of triple negative breast cancer (TNBC), as effective targeted therapy would make a considerable impact. At the transcriptome level, TNBC most frequently overlaps the intrinsic subtype referred to as "Basal-like''. However other less common subtypes, including "Claudin-low", "HER2-enriched but without HER2 gene amplification", "Luminal B", "Luminal A" and "Molecular apocrine'' subtypes have also been described in TNBC. Additionally TNBC tumors that arise in the setting of a germ-line BRCA1 mutation may be considered a separate entity because of their potential susceptibility to poly ADP ribose polymerase (PARP) inhibitor therapy. With the advent of whole genome sequencing, we envision further classification of TNBC that is based on genetic abnormalities linked to targeted therapeutics.

Phase II trial of temsirolimus in patients with metastatic breast cancer

Preclinical models suggested that activating mutations of the PIK3CA gene are associated with sensitivity to inhibitors of the mammalian target of rapamycin (mTOR). In breast cancers, PIK3CA mutations are associated with estrogen receptor (ER) positivity. We therefore performed an open-label single arm phase II study of the rapamycin analog, temsirolimus, at a dose of 25 mg weekly, in women with pretreated breast cancers that were positive for ER, PR, or HER2. Archived formalin-fixed paraffin embedded tumor was collected for immunohistochemical evaluation of components of the PI3K/Akt/mTOR pathway and PIK3CA mutation analysis. Thirty-one patients were enrolled. There were no major objective responses; however, three patients had stable disease for over 24 weeks. Twenty-three tumor samples were available for mutational analysis. There were five tumors with PIK3CA mutations; no association was found between prolonged stable disease and PIK3CA mutation or any immunohistochemical marker. There was a trend toward improved progression free survival (PFS) for patients with positive nuclear staining for phospho-Akt308. One patient remains on study four and a half years after starting therapy; her tumor did not have a PIK3CA mutation. We conclude that single agent temsirolimus has minimal activity in a population of women with heavily pretreated breast cancer. We found no evidence that either absence of immunohistochemical staining for PTEN or mutations in the hotspot domains of PIK3CA in the primary tumor were associated with clinical benefit.

Neoadjuvant chemotherapy is associated with improved survival compared with adjuvant chemotherapy in patients with triple-negative breast cancer only after complete pathologic response

INTRODUCTION

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer that is known to be chemosensitive. In patients with TNBC, we sought to compare survival outcomes between patients receiving neoadjuvant chemotherapy, with and without complete pathologic response (pCR), and those receiving adjuvant chemotherapy.

METHODS

We performed a retrospective chart review and identified 385 patients with stage I-III TNBC who were treated with neoadjuvant or adjuvant chemotherapy between 2000 and 2008. Patients were divided according to receipt of neoadjuvant chemotherapy with pCR, neoadjuvant chemotherapy without pCR, and adjuvant chemotherapy. Data were compared using Fisher's exact test and analysis of variance (ANOVA). Kaplan-Meier curves were generated.

RESULTS

Of 385 patients, 151 (39%) received neoadjuvant chemotherapy and 234 (61%) received adjuvant chemotherapy. Twenty-six (17%) of those patients receiving neoadjuvant chemotherapy had pCR. After controlling for covariates associated with survival in unadjusted tests, patients undergoing neoadjuvant chemotherapy with residual tumor had significantly worse survival compared with patients receiving adjuvant therapy [hazard ratio (HR) = 0.51, P = 0.007] and a trend towards worse survival compared with patients receiving neoadjuvant therapy with pCR (HR = 0.19, P = 0.10).

CONCLUSIONS

Although previous clinical trials have not demonstrated a survival difference between patients receiving neoadjuvant versus adjuvant chemotherapy for breast cancer, our study suggests an overall survival benefit in patients with pCR following neoadjuvant chemotherapy compared with patients receiving adjuvant therapy. It is clear that a prospective study needs to be carried out to better elucidate the timing of chemotherapy in patients with TNBC.

Importance of PI3-kinase pathway in response/resistance to aromatase inhibitors

Endocrine therapy has been the most effective treatment modality for hormone receptor positive breast cancer. However, its efficacy has been limited by either de novo or acquired resistance. Recent data indicates that activation of the phosphatidylinositol 3-kinase (PI3K) signaling is associated with the poor outcome luminal B subtype of breast cancer and accompanied by the development of endocrine therapy resistance. Importantly, inhibition of PI3K pathway signaling in endocrine resistant breast cancer cell lines reduces cell survival and improves treatment response to endocrine agents. Interestingly, mutations in PIK3CA, the alpha catalytic subunit of the class IA PI3K, which renders cells dependent on PI3K pathway signaling, is the most common genetic abnormality identified in hormone receptor positive breast cancer. The synthetic lethality observed between estrogen deprivation and PI3K pathway inhibition in estrogen receptor positive (ER+) breast cancer cell lines provides further scientific rational to target both estrogen receptor and the PI3K pathway in order to improve the outcome of ER+ breast cancer.

Preclinical modeling of combined phosphatidylinositol-3-kinase inhibition with endocrine therapy for estrogen receptor-positive breast cancer

Introduction

Inhibition of phosphatidylinositol-3-kinase (PI3K) induces apoptosis when combined with estrogen deprivation in estrogen receptor (ER)-positive breast cancer. The aims of the present study were to identify effective PI3K pathway inhibitor and endocrine therapy combinations, to evaluate the effect of PI3K pathway mutations and estrogen dependency on tumor response, and to determine the relevance of PIK3CA mutation in recurrent disease.

Methods

The PI3K catalytic subunit inhibitor BKM120, the mammalian target of rapamycin (mTOR) inhibitor RAD001 and the dual PI3K/mTOR inhibitor BGT226 were tested against ER-positive breast cancer cell lines before and after long-term estrogen deprivation (LTED). The impact of estradiol deprivation and the ER downregulator fulvestrant on PI3K pathway inhibitor-induced apoptosis was assessed. PIK3CA hotspot mutation analysis was performed in 51 recurrent or metastatic breast cancers and correlated with ER status and survival.

Results

Drug-induced apoptosis was most marked in short-term estrogen-deprived cells with PIK3CA mutation and phosphatase and tensin homolog loss. Apoptosis was most highly induced by BGT226, followed by BKM120, and then RAD001. Estradiol antagonized PI3K inhibitor-induced apoptosis following short-term estrogen deprivation, emphasizing a role for estrogen-deprivation therapy in promoting PI3K inhibitor activity in the first-line setting. ER-positive MCF7 LTED cells exhibited relative resistance to PI3K pathway inhibition that was reversed by fulvestrant. In contrast, T47D LTED cells exhibited ER loss and ER-independent PI3K agent sensitivity. PIK3CA mutation was prevalent in relapsed ER-positive disease (48%) and was associated with persistent ER positivity and a late relapse pattern.

Conclusions

Estrogen deprivation increased the apoptotic effects of PI3K and dual PI3K/mTOR inhibitors in ER-positive disease, providing a rationale for PI3K/aromatase inhibitor combinations as first-line therapy. In LTED cells, differential effects on ER expression may be a relevant consideration. When ER was persistently expressed, fulvestrant strongly promoted PI3K drug activity. When ER was lost, PI3K inhibitor monotherapy was sufficient to induce high-level apoptosis. Although tumors with PIK3CA mutation had a late recurrence pattern, these mutations were common in metastatic disease and were most often associated with persistent ER expression. Targeting PIK3CA mutant tumors with a PI3K pathway inhibitor and fulvestrant is therefore a feasible strategy for aromatase-inhibitor-resistant ER-positive relapsed breast cancer.

Aromatase gene polymorphisms are associated with survival among patients with cardiovascular disease in a sex-specific manner

Introduction

CYP19A1 encodes aromatase, the enzyme responsible for the conversion of androgens to estrogens, and may play a role in variation in outcomes among men and women with cardiovascular disease. We sought to examine genetic variation in CYP19A1 for its potential role in sex differences in cardiovascular disease outcomes.

Methods

Caucasian individuals from two independent populations were assessed: 1) a prospective cohort of patients with acute coronary syndromes with 3-year mortality follow-up (n = 568) and 2) a nested case-control study from a randomized, controlled trial of hypertension patients with stable coronary disease in which the primary outcome was death, nonfatal myocardial infarction (MI) or nonfatal stroke (n = 619). Six CYP19A1 SNPs were genotyped (-81371 C>T, -45965 G>C, M201T, R264C, 80 A>G, and +32226 G>A). The sex*genotype interaction term was assessed for the primary outcome and compared by genotype in men and women when a significant interaction term was identified.

Results

We identified a significant interaction between -81371 C>T and sex (p = 0.025) in the ACS population. The variant allele was associated with a 78% increase in mortality in men (HR 1.78, 95% confidence interval [CI] 1.08-2.94) and a nonsignificant 42% decrease in mortality among women (HR 0.58, 95% CI 0.22-1.54). We identified a similar association in the hypertensive CAD group, the -81371 C>T*sex interaction term was p<0.0001, with an associated 65% increase in death, MI, or stroke (HR 1.65, 95% CI 1.00-2.73) in men and a 69% decrease (HR 0.31, 95% CI 0.16-0.6) in women.

Conclusions

Using two independent populations, this study is the first to document a significant interaction between CYP19A1 genotype and sex on cardiovascular outcomes. These findings could illuminate potential mechanisms of sex differences in cardiovascular disease outcomes.

Neoadjuvant endocrine therapy in primary breast cancer: indications and use as a research tool

Neoadjuvant endocrine therapy has been increasingly employed in clinical practice to improve surgical options for postmenopausal women with bulky hormone receptor-positive breast cancer. Recent studies indicate that tumour response in this setting may predict long-term outcome of patients on adjuvant endocrine therapy, which argues for its broader application in treating hormone receptor-positive disease. From the research perspective, neoadjuvant endocrine therapy provides a unique opportunity for studies of endocrine responsiveness and the development of novel therapeutic agents.

Predicting endocrine therapy responsiveness in breast cancer

Endocrine therapy is one of the most effective treatment strategies for breast cancer. However, in the adjuvant setting, up to 40% to 50% of patients with estrogen receptor (ER)-positive breast cancers relapse despite these interventions. Although ER and HER2 analysis has increased our ability to predict which patients will benefit from endocrine therapy, further improvement is needed, most specifically for patients with ER-positive, HER2-negative disease. Recent advances in genomic technology have made it possible to classify breast cancers into risk categories with significant prognostic implications. However, the predictive value of these tests remains the subject of investigation. Long-term follow-up of neoadjuvant endocrine therapy studies suggests that the in vivo assessment of therapeutic efficacy provided by this treatment approach is also valuable in predicting outcome. Indeed, the Preoperative Endocrine Prognostic Index (PEPI), based on tumor pathologic staging and expression levels of ER and Ki67 following 3 to 4 months of neoadjuvant endocrine therapy, reproducibly predicts long-term outcomes of hormone receptor-positive breast cancer. This article reviews ongoing progress in the effort to identify predictors of endocrine therapy responsiveness for breast cancer and discusses the value of "pre-treatment" vs "on-treatment" tumor profiling for predicting outcomes.

Targeted therapies for triple negative breast cancer based on TP53 status

Abstract #403

Background: Triple negative breast cancer (TNBC: negative for ER, PR and HER2) presents a significant clinical challenge. The frequent occurrence of mutations in TP53, the gene encoding the p53, in TNBC provides an opportunity for therapeutic intervention. p53 is required for cells to respond to DNA damage in the G1 phase of the cell cycle. Tumors with a defective p53 pathway fail to arrest (or undergo apoptosis) in G1 and rely on p53-independent pathways at S and G2 for their survival following DNA damage. Therefore, a potential therapeutic strategy for TP53 mutant tumors is to inhibit the S- and G2-checkpoints. Chk1 is a key regulator of both the S- and G2- checkpoints as such, p53 mutant cells are absolutely dependent on Chk1 activity to respond to DNA damage. This property makes Chk1 a potential therapeutic target in p53 defective tumors. Therefore, we tested the combination of irinotecan (DNA damaging agent) and UCN-01 (non-specific Chk1 inhibitor) in a preclinical model of TNBC. This combination was chosen based on preliminary results obtained in patients with TNBC on a Phase I trial conducted at our institution. UCN-01 is also a potent inhibitor of PDK1 and therefore inhibits the PI3K pathway. Given that PTEN is frequently deficient in TNBC, we also monitored components of the PI3K pathway in our preclinical model of TNBC.&#x2028; Material and Method: Tumor biopsies from patients with TNBC were engrafted into the humanized mammary fat pad of immunodeficient NOD/SCID mice. TP53 was sequenced in each engrafted tumor explant and the integrity of the p53 pathway was determined by monitoring p53 stabilization and p21 induction following DNA damage. Three independent TNBC tumor explants, one wild-type and two mutant for TP53 were analyzed for their response to irinotecan and UCN-01 either as single agents or in combination. UCN-01 was administered 24h post irinotecan in mice treated with the combination. Mice were sacrificed 48 h later and tumors were harvested and analyzed for cell cycle arrest (geminin, pCdk1), DNA damage (pChk1, gamma H2AX), apoptosis (cleaved caspase 3), checkpoint bypass (pHistone H3) and the PI3K pathway (pS6) by Western blotting and immunohistochemistry.&#x2028; Results: Expression profiling revealed that the characteristics of the tumor are preserved in the tumor explants suggesting this is a valid model system to study experimental therapy for TNBC. Irinotecan induced similar levels of DNA damage in TP53 wild-type and TP53 mutant TNBCs. UCN-01 potently inhibited levels of pS6 independent of p53 status. Strikingly, the combination of irinotecan and UCN-01 selectively induced checkpoint bypass and apoptosis in p53 mutant TNBCs.&#x2028; Conclusion: p53 status is a significant predictor of response to combination therapies involving DNA damage followed by Chk1 inhibition. Tumors, like TNBC, that frequently lack a functional p53 pathway may be effectively treated using this strategy. Studies are underway to test different chemotherapy agents and more selective Chk1 and PI3K inhibitors in this preclinical model of TNBC.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 403.

Characterization of phytoene synthase 1 gene (Psy1) located on common wheat chromosome 7A and development of a functional marker

Phytoene synthase (Psy), a critical enzyme in the carotenoid biosynthetic pathway, demonstrated high association with the yellow pigment (YP) content in wheat grain. Characterization of Psy genes and the development of functional markers for them are of importance for marker-assisted selection in wheat breeding. In this study, the full-length genomic DNA sequence of a Psy gene (Psy-A1) located on chromosome 7A, was characterized by in silico cloning and experimental validation. The cloned Psy-A1 comprises six exons and five introns, 4,175 bp in total, and an ORF of 1,284 bp. A co-dominant marker, YP7A, was developed based on polymorphisms of two haplotypes of Psy-A1, yielding 194 and 231-bp fragments in cultivars with high and low YP content, respectively. The marker YP7A was mapped on chromosome 7AL using an RIL population from cross PH82-2/Neixing 188, and a set of Chinese Spring nullisomic-tetrasomic lines and ditelosomic line 7AS. Psy-A1, co-segregating with the STS marker YP7A, was linked to SSR marker Xwmc809 on chromosome 7AL with a genetic distance of 5.8 cM, and explained 20-28% of the phenotypic variance for YP content across three environments. A total of 217 Chinese wheat cultivars and advanced lines were used to validate the association between the polymorphic band pattern and grain YP content. The results showed that the functional marker YP7A was closely related to grain YP content and, therefore, could be used in wheat breeding programs targeting of YP content for various wheat-based products.

Neoadjuvant endocrine therapy for locally advanced breast cancer

Patients with locally advanced breast cancer are frequently treated with preoperative (neoadjuvant) systemic therapy to downstage the tumor and improve surgical outcomes. The conventional approach has been to administer chemotherapy but for estrogen receptor-positive (ER+) tumors endocrine therapy is a logical alternative. Neoadjuvant endocrine therapy was initially investigated in older or medically frail individuals who were poor candidates for cytotoxic drugs. However, indirect comparisons suggest that preoperative endocrine therapy with an aromatase inhibitor promotes breast conservation probably as frequently as chemotherapy. As a result, primary systemic therapy with an aromatase inhibitor is now being explored in a younger, healthier population. A key advance would be the development of predictive biomarkers so that this treatment can be more confidently incorporated into routine clinical practice. Interestingly, it seems logical that such a test also would identify patients with highly endocrine therapy-responsive tumors that do not derive much benefit from adjuvant chemotherapy. The American College of Surgeons Oncology Group and the Central Clinical Trials Unit recently activated a neoadjuvant aromatase inhibitor trial with these aims in mind. In this review, we outline the rationale for preoperative endocrine therapy, and consider predictive models for endocrine therapy responsiveness in this setting.

A comprehensive examination of CYP19 variation and risk of breast cancer using two haplotype-tagging approaches

BACKGROUND

Numerous studies point to a positive relationship between elevated levels of estrogens and increased risk of breast. Androgens are converted to estrogens by the aromatase enzyme, which is encoded by the CYP19 gene. We recently published resequencing data on 88 polymorphisms identified in that gene. The hypothesis tested in this study was that polymorphisms, or haplotypes, in CYP19 are related to risk of breast cancer.

METHODS

Incident cases of breast cancer were identified through the Division of Medical Oncology at the Mayo Clinic in Rochester, MN. Controls were patients visiting Mayo for an annual medical examination. Controls were frequency matched to cases based on age and region of residence. Tag-polymorphisms were selected using 2 methods: (1) 12 variants using the tag-selection method of Carlson et al. (Am J Hum Genet 74:106-120, 2004); and (2) 12 variants using the haplotype method of Stram (Genet Epidemiol 27:365-374, 2004). Six SNPs were selected by both methods. Genotyping was conducted using SNPStream, TaqMan and RFLP analyses. Logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI). Analyses were conducted among all cases and controls, or stratified by estrogen receptor alpha (ER) status and/or menopausal status.

RESULTS

A total of 750 cases (60% postmenopausal) and 732 controls (75% postmenopausal) were included. No association with breast cancer risk was detected for individual variants, selected tagSNPs or hap-tag SNPs despite 80% power to detect OR as low as 1.49 for minor allele frequency (MAF) of 0.10. Similarly, stratified analyses based on ER status or menopausal status failed to detect any association with breast cancer risk.

CONCLUSION

These analyses suggest that variants of CYP19 are not associated with risk of breast cancer.

A phase II trial of a combination of pemetrexed and gemcitabine in patients with metastatic breast cancer: an NCCTG study

PURPOSE

This phase II study was undertaken to define the efficacy and toxicity of pemetrexed in combination with gemcitabine in patients with metastatic breast cancer.

PATIENTS AND METHODS

Patients with measurable metastatic breast cancer who had previously received an anthracycline and a taxane in either the adjuvant or metastatic setting were treated with gemcitabine 1250 mg/m2 (intravenous; days 1 and 8) and pemetrexed 500 mg/m2 (intravenous; day 8) every 21 days.

RESULTS

Fifty-nine patients received a median of five cycles (range one to 22) of treatment and were followed until death or for a median of 28 months (range 19.4-36.6) among living patients. Fourteen partial responses for an overall response rate of 24% [95% confidence interval (CI) 16% to 39%] were documented. Nine (15%; CI 5% to 32%) patients had stable disease for >6 months. The median survival time was 10.3 months (95% CI 8.3-18.9) and the 1 year survival rate was 49% (95% CI 38% to 64%). The median time to progression was estimated to be 3.7 months (95% CI 2.3-5.3). The most common grade 3 or 4 toxicities were neutropenia and thrombocytopenia in 83% and 27% of patients, respectively. Fourteen percent of patients experienced febrile neutropenia. Other common grade 3 or 4 non-hematological toxicities included fatigue (17%), dyspnea (15%), rash (7%) and anorexia (5%).

CONCLUSIONS

The combination of pemetrexed and gemcitabine is clinically active, with an overall response rate of 24% in patients with metastatic breast cancer who have previously been treated with an anthracycline and a taxane. Myelosuppression (66% grade 4 neutropenia and 14% febrile neutropenia) was the major treatment-related toxicity observed for this combination.

Starch properties of mutant rice high in resistant starch

As the staple food of over half the world's population, hot cooked rice high in resistant starch (RS) is of particular interest, which will have greater impact in the dietary prevention of diabetes and hyperlipidemia. A mutant rice high in RS in hot cooked rice, described as RS111, was comparatively studied with the wild type and common rice. Despite obviously low RS content in the raw milled rice, the RS content in the hot cooked rice of mutant RS111 was significantly higher than that of the wild type and common rice and, correspondingly, in vitro starch hydrolysis by porcine pancreatic alpha-amylase tends to be incomplete with low hydrolysis extent for the cooked mutant rice high in RS. Obvious differences in physicochemical properties, starch granule morphology, pasting properties, thermal properties, and X-ray diffraction pattern were observed among the mutant RS111, wild type, and common indica rice. The high-RS mutant was characterized by significantly higher apparent amylose content and crude lipid content, higher percentage of oval-shaped granules and bigger oval size, reduced paste viscosity, and low onset temperature, peak temperature, final temperature, enthalpy of gelatinization, and crystallinity.

Human aromatase: gene resequencing and functional genomics

Aromatase [cytochrome P450 19 (CYP19)] is a critical enzyme for estrogen biosynthesis, and aromatase inhibitors are of increasing importance in the treatment of breast cancer. We set out to identify and characterize genetic polymorphisms in the aromatase gene, CYP19, as a step toward pharmacogenomic studies of aromatase inhibitors. Specifically, we "resequenced" all coding exons, all upstream untranslated exons plus their presumed core promoter regions, all exon-intron splice junctions, and a portion of the 3'-untranslated region of CYP19 using 240 DNA samples from four ethnic groups. Eighty-eight polymorphisms were identified, resulting in 44 haplotypes. Functional genomic studies were done with the four nonsynonymous coding single nucleotide polymorphisms (cSNP) that we observed, two of which were novel. Those cSNPs altered the following amino acids: Trp39Arg, Thr201Met, Arg264Cys, and Met364Thr. The Cys264, Thr364, and double variant Arg39Cys264 allozymes showed significant decreases in levels of activity and immunoreactive protein when compared with the wild-type (WT) enzyme after transient expression in COS-1 cells. A slight decrease in protein level was also observed for the Arg39 allozyme, whereas Met201 displayed no significant changes in either activity or protein level when compared with the WT enzyme. There was also a 4-fold increase in apparent K(m) value for Thr364 with androstenedione as substrate. Of the recombinant allozymes, only the double mutant (Arg39Cys264) displayed a significant change from the WT enzyme in inhibitor constant for the aromatase inhibitors exemestane and letrozole. These observations indicate that genetic variation in CYP19 might contribute to variation in the pathophysiology of estrogen-dependent disease.

Randomized phase II trial of three schedules of pemetrexed and gemcitabine as front-line therapy for advanced non-small-cell lung cancer

PURPOSE

A randomized three-arm phase II study was undertaken to evaluate the optimum administration schedule of pemetrexed and gemcitabine in chemotherapy-naïve patients with non-small-cell lung cancer.

PATIENTS AND METHODS

Patients were randomly assigned to three schedules of pemetrexed 500 mg/m2 plus gemcitabine 1,250 mg/m2, separated by a 90-minute interval, on a 21-day cycle as follows: schedule A, pemetrexed followed by gemcitabine on day 1 and gemcitabine on day 8; schedule B, gemcitabine followed by pemetrexed on day 1 and gemcitabine on day 8; and schedule C, gemcitabine on day 1 and pemetrexed followed by gemcitabine on day 8.

RESULTS

One hundred fifty-two eligible patients (schedule A, n = 59; schedule B, n = 31, and schedule C, n = 62) received a median of five (schedule A), two (schedule B), and four (schedule C) treatment cycles. Overall, 66% of patients experienced grade 3 or 4 neutropenia. Common grade 3 and 4 nonhematologic toxicities were dyspnea (11%), fatigue (16%), and transaminase elevation (9%). Schedule A seemed less toxic compared with schedule C (grade 3 or 4 events: 86% v 94%, respectively; P = .19; grade 4 events: 39% v 48%, respectively; P = .30). Schedule B was closed at interim analysis for inferior efficacy. Schedule A, with a confirmed response rate of 31% (95% CI, 20% to 45%), met the protocol-defined efficacy criteria, whereas schedule C, with a confirmed response rate of 16.1% (95% CI, 11% to 34%), did not. Median survival time and time to progression were 11.4 and 4.4 months, respectively, with no observable difference between the arms.

CONCLUSION

Pemetrexed and gemcitabine administered as outlined for schedule A met the protocol-defined efficacy criteria, was less toxic compared with the other treatment schedules, and should be further evaluated.

Acquired Fanconi syndrome is an indolent disorder in the absence of overt multiple myeloma

Adult-acquired Fanconi syndrome (FS) is a rare complication of monoclonal gammopathy. We retrospectively reviewed 32 patients diagnosed with adult-acquired FS between April 1968 and June 2002 at Mayo Clinic (Rochester, MN). At diagnosis, most patients had monoclonal gammopathy of undetermined significance (MGUS) or smoldering multiple myeloma (SMM), with a median creatinine level of 176.8 μM (2.0 mg/dL; range, 79.56-327.08 μM [0.9-3.7 mg/dL]) and evidence of osteomalacia. During the average 65 months (range, 2-238 months) of follow-up, 5 patients developed end-stage renal disease (ESRD) and only 1 of 14 patients with MGUS transformed to multiple myeloma (MM). Also, 14 deaths occurred, with only 1 from ESRD but 4 from alkylator-related leukemia or myelodysplastic syndrome. Chemotherapy offered little benefit on renal functions of MGUS or SMM patients. In conclusion, FS associated with monoclonal gammopathy does not appear to confer an additional risk of subsequent evolution to MM. ESRD occurs late in the disease process.

A multivalent pairing model of linkage analysis in autotetraploids

Polyploidy has been recognized as an important step in the evolutionary diversification of flowering plants and may have a significant impact on plant breeding. Statistical analyses for linkage mapping in polyploid species can be difficult due to considerable complexities in polysomic inheritance. In this article, we develop a novel statistical method for linkage analysis of polymorphic markers in a full-sib family of autotetraploids. This method is established on multivalent pairings of homologous chromosomes at meiosis and can provide a simultaneous maximum-likelihood estimation of the double reduction frequencies of and recombination fraction between two markers. The EM algorithm is implemented to provide a tractable way for estimating relative proportions of different modes of gamete formation that generate identical gamete genotypes due to multivalent pairings. Extensive simulation studies were performed to demonstrate the statistical properties of this method. The implications of the new method for understanding the genome structure and organization of polyploid species are discussed.

[Application of skin and soft tissue expansion in treatment of burn injury]

OBJECTIVE

To evaluate the application of skin and soft tissue expansion in the treatment of deformity due to extensive severe burn injury and repair of severe deep electrical burned scalp and skull with fresh wound.

METHODS

From 1988, 83 cases of application of skin and soft tissue expansion were reported. In those patients with deformity due to severe burn of large area and with whole nasal defect, soft tissue expander was used under the forehead skin graft and venter frontalis, followed by reconstruction of nose with the expanded vascularized skin flap and carved cartilago costalis as nasal frame. In patients of severe deep electrical burned scalp and skull with fresh wound, skin and soft tissue expansion were used to repair the wound simultaneously with scalp burn alopecia, anesthetics and antibiotics injected into the extracapsular space of the expander in case of pain and infection.

RESULTS

All of the cases were successfully treated with little pain and minimized infection.

CONCLUSION

Skin and soft tissue expansion in a safe and reliable measure in the treatment of deformity due to extensive severe burn injury and repair of severe deep electrical burned scalp and skull with fresh wound.

Experimental study of early diagnosis and treatment of fat embolism syndrome

An experimental animal model has been established using i.v. fat injection to mimic fat embolism syndrome (FES). Fourteen healthy mongrel dogs who were administered 0.7 ml/kg of fluid marrow fat obtained from the long bone marrow cavity of mongrel dogs were divided into control and therapeutic groups. The therapeutic group (n = 7) was given dexamethasone (1.0 mg/kg) and repeated every 6 h i.v. During 48 h of observation, blood gas analysis and frozen sections were performed on blood samples collected from the pulmonary vessels by a floating catheter and from a peripheral vein at different time intervals. The frozen sections were stained with Oil Red O. Positive results were seen 2 h after fat injection in both pulmonary and peripheral blood samples of both control and therapeutic groups. By computer image analysis, the average median number of fat droplets per section and the average median diameter of fat droplets in pulmonary blood of the control group were found to be significantly higher and larger than were those of the therapeutic group. The average median number and diameter of fat droplets in pulmonary blood were significantly higher and larger than were those of peripheral blood in both control and therapeutic groups. These findings correlated well with blood gas changes and the clinical appearance of the experimental animals. The fat droplets from pulmonary or peripheral blood as demonstrated by Oil Red O staining in combination with blood gases changes [PaO2 < 7.99 KPa, difference between the alveolar and arterial oxygen tension (P(A - a)O2) > 6.09 KPa] may be a rapid method for screening of an earlier diagnosis of FES.(ABSTRACT TRUNCATED AT 250 WORDS)

Langerhans cells in nasopharyngeal carcinoma in relation to prognosis

Langerhans cells (LC) and macrophages in 119 cases of nasopharyngeal carcinoma and 19 cases of nasopharyngeal mucosa obtained from non-cancer patients were studied by SPA immunohistochemical methods with the use of antibodies against S-100 protein and lysozyme, respectively. The distribution of LC in the tumor tissue was different from that in macrophages. Patients with dense infiltration of LC in the tumor tissue survived longer than those without such infiltration (mean survival times, 26.9, 51.7 and 72.6 months in the patients with -, + and ++ density, respectively: P < 0.005). There was no relationship between patient prognosis and density of macrophages (P > 0.25). LC may play an important role in tumor immunity and may be taken as one of the criteria of prognosis.

[The effects of injection salviae miltiorrhizae in preventing and treating fat embolism syndrome]

This study was to examine the effects and mechanisms of injectio salviae miltiorrhizae (ISM) in preventing and treating fat embolism syndrome (FES), which was simulated by intravenous injection of homologous bone marrow fat in 16 dogs. PaO2, free fatty acids (FFAs), TXA2/PGI2, SOD/MDA were measured in different times combined with X-ray, conjunctiva microcirculation observation, radioisotope scanning and histologic examination. It was found that in the control group there were a significant fall in PaO alpha and rise in FFAs and MDA; blood clot stained with oil red O showed many fat droplets; radioisotope scanning revealed mild hypoperfusion or perfusion defects. In the treatment group, arterial oxygen levels were maintained, serum level of FFAS and MDA was reduced significantly. It is concluded that there is damage induced by oxygen-derived radicals in FES, LSM is an effective therapy for the FES, and 99mTc radioisotope scanning is a promising technique for noninvasive identification of FES in the early stage.

Electron microscopic observations on the synaptonemal complex of spermatocytes of the giant panda (Ailluropoda melanoleuca)

Surface-spread and silver-stained preparations of spermatocytes from a giant panda were observed by electron microscopy for synaptonemal complex karyotyping. Ten pachytene spermatocyte nuclei were selected for length quantitation of SC. The mean relative lengths and centromeric indices of each SC agreed closely with those of the mitotic chromosomes. The pairing between lateral elements of autosomal chromosomes starts at early zygotene and leads progressively along their length to complete pairing at pachytene. The whole Y is paired with 1/3 length of X at mid-pachytene. The morphology of X and Y chromosome axes and the nonhomologous pairing of X and Y is discussed.