Stefania Landolfi

Lapatinib, a HER2 tyrosine kinase inhibitor, induces stabilization and accumulation of HER2 and potentiates trastuzumab-dependent cell cytotoxicity

Lapatinib is a human epidermal growth factor receptor 2 (HER2) tyrosine kinase inhibitor (TKI) that has clinical activity in HER2-amplified breast cancer. In vitro studies have shown that lapatinib enhances the effects of the monoclonal antibody trastuzumab suggesting partially non-overlapping mechanisms of action. To dissect these mechanisms, we have studied the effects of lapatinib and trastuzumab on receptor expression and receptor signaling and have identified a new potential mechanism for the enhanced antitumor activity of the combination. Lapatinib, given alone or in combination with trastuzumab to HER2-overexpressing breast cancer cells SKBR3 and MCF7-HER2, inhibited HER2 phosphorylation, prevented receptor ubiquitination and resulted in a marked accumulation of inactive receptors at the cell surface. By contrast, trastuzumab alone caused enhanced HER2 phosphorylation, ubiquitination and degradation of the receptor. By immunoprecipitation and computational protein modeling techniques we have shown that the lapatinib-induced HER2 accumulation at the cell surface also results in the stabilization of inactive HER2 homo- (HER2/HER2) and hetero- (HER2/EGFR and HER2/HER3) dimers. Lapatinib-induced accumulation of HER2 and trastuzumab-mediated downregulation of HER2 was also observed in vivo, where the combination of the two agents triggered complete tumor remissions in all cases after 10 days of treatment. Accumulation of HER2 at the cell surface by lapatinib enhanced immune-mediated trastuzumab-dependent cytotoxicity. We propose that this is a novel mechanism of action of the combination that may be clinically relevant and exploitable in the therapy of patients with HER2-positive tumors.

Risk factors for positive findings in patients with high-grade T1 bladder cancer treated with transurethral resection of bladder tumour (TUR) and bacille Calmette-Guérin therapy and the decision for a repeat TUR

Study Type – Therapy (case series)

Epigenetic Homogeneity Within Colorectal Tumors Predicts Shorter Relapse-Free and Overall Survival Times for Patients With Locoregional Cancer

BACKGROUND & AIMSnThere are few validated biomarkers that can be used to predict outcomes for patients with colorectal cancer. Part of the challenge is the genetic and molecular heterogeneity of colorectal tumors not only among patients, but also within tumors. We have explored intratumor heterogeneity at the epigenetic level, due to its dynamic nature. We analyzed DNA methylation profiles of the digestive tract surface and the central bulk and invasive front regions of colorectal tumors.nnnMETHODSnWe determined the DNA methylation profiles of >450,000 CpG sites in 3 macrodissected regions of 79 colorectal tumors and 23 associated liver metastases, obtained from 2 hospitals in Spain. We also analyzed samples for KRAS and BRAF mutations, 499,170 single nucleotide polymorphisms, and performed immunohistochemical analyses.nnnRESULTSnWe observed differences in DNA methylation among the 3 tumor sections; regions of tumor-host interface differed the most from the other tumor sections. Interestingly, tumor samples collected from areas closer to the gastrointestinal transit most frequently shared methylation events with metastases. When we calculated individual coefficients to quantify heterogeneity, we found that epigenetic homogeneity was significantly associated with short time of relapse-free survival (log-rank Pxa0= .037) and short time of overall survival (log-rank Pxa0= .026) in patients with locoregional colorectal cancer.nnnCONCLUSIONSnIn an analysis of 79 colorectal tumors, we found significant heterogeneity in patterns of DNA methylation within each tumor; the level of heterogeneity correlates with times of relapse-free and overall survival.

Pre-operative chemoradiotherapy with UFT and Leucovorin in patients with advanced rectal cancer: A phase II study

PURPOSEnThe aim this study was to determine the pathologic complete response (pCR) rate defined as tumor regression grade 1 (TRG1) and toxicity profile of the combination of high-dose pre-operative radiotherapy and simultaneous UFT/leucovorin (LV) in patients with locally advanced rectal cancer.nnnMATERIALS/METHODSnEligibility included biopsy proven rectal adenocarcinoma; T3-T4 N0-N2; performance status < 2 (ECOG) and adequate blood, hepatic and renal function. Treatment consisted of radiotherapy 54 Gy at 1.8 Gy/day and UFT 300 mg/m(2)/day and LV 60 mg/day, given simultaneously daily for 6 weeks. Surgery was performed within 4-6 weeks period after chemoradiotherapy. Patients who did not achieve TGR1 were to receive 4 cycles of adjuvant UFT/LV on days 1-28, every 5 weeks.nnnRESULTSnSixty-eight patients were included. All but one received full dose of radiation and 62 had the total planned pre-operative UFT/LV dose. Grade 3 toxicities were diarrhea 7% and proctitis 3%. Complete resection was achieved in 62 patients (91%). Tumor regression grade 1 (TRG1) was seen in 11 patients (16%). Forty-eight patients received adjuvant UFT/LV. Grade 3 toxicity during adjuvant UFT/LV included diarrhea 12%, asthenia 4%, neutropenia 2%, and hand-foot syndrome 2%. The 3-year disease-free survival was 71%.nnnCONCLUSIONSnSimultaneous high-dose pre-operative localized radiation therapy concurrent with UFT/LV is feasible and has a low toxicity profile. This schedule is highly effective and merits further investigation.

Updated guidelines for biomarker testing in colorectal carcinoma: a national consensus of the Spanish Society of Pathology and the Spanish Society of Medical Oncology

Publication of this consensus statement is a joint initiative of the Spanish Society of Pathology (SEAP) and the Spanish Society of Medical Oncology (SEOM), intended to revise and update the diagnostic and treatment recommendations published 2xa0years ago on biomarker use and the management of patients with colorectal carcinoma (CRC), thereby providing an opportunity to improve healthcare efficiency and resource use in these patients. This expert group recommends testing for KRAS and NRAS status in all patients with metastatic CRC being considered for anti-epidermal growth factor receptor (anti-EGFR) therapy, as this type of treatment should only be used in patients not harbouring mutations in these genes. In contrast, testing for BRAF, EGFR, PI3K and PTEN mutation status is not necessary for therapeutic decision making, so does not need to be done routinely.

Abstract 5756: The receptor tyrosine kinase EPHB4 has tumor suppressor activities in intestinal tumorigenesis

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DCnnColorectal cancer is the second cause of cancer related death in the western world and although the genetic and molecular mechanisms involved in initiation and progression of these tumors is among the best characterized, there are significant gaps in our understanding of this disease. The family of receptor tyrosine kinases EPH and their Ephrin ligands regulate cell proliferation, migration and attachment. An important role in colorectal carcinogenesis is emerging for some of its members. In this study we used animal models and analysis of large tumor collections to investigate the possible role of EPHB4 as a new tumor suppressor gene in colorectal cancer. Modulation of EPHB4 levels in colon cancer cell lines resulted in significant growth differences in vitro and in a xenograft model, with low levels of EPHB4 associated with faster growth. In addition, using a genetic model of intestinal tumorigenesis where Apc mutations lead to initiation of the tumorigenic process (Apcmin mice), we show that inactivation of a single allele of EphB4 results in: a) higher proliferation both in the normal epithelium and intestinal tumors, b) significantly larger tumors in the small intestine and c) a 10-fold increase in the number of tumors in the large intestine. This was associated with a 25% reduction in the lifespan of Apcmin mice (p<0.0001). Gene expression analysis demonstrated that EphB4 inactivation causes a profound transcriptional reprogramming affecting genes involved in cell proliferation, remodeling of the extracellular matrix and cell attachment to the basement membrane, among other functional groups of genes. Importantly, in agreement with the expression profiling experiments, using an in vitro assay we demonstrate that loss of EPHB4 in colon cancer cells results in a significantly increased potential to invade through a complex extracellular matrix. In addition, using archived human colorectal tumors we investigated the possible association between EPHB4 levels and patient prognosis. In a series of 252 cases, we found that EPHB4 expression is frequently reduced or lost in colorectal tumors. Patients with low EPHB4 tumor levels had significantly shorter survival than patients in the high EPHB4 group (Logrank test p<0.01; median survival of 1.8 and over 9 years, respectively). Moreover, we demonstrate that EPHB4 promoter hypermethylation is a common mechanism of EPHB4 inactivation. Collectively, these results indicate that EPHB4 has tumor suppressor activities in colorectal cancer and that tumor expression of this tyrosine kinase can be used to predict patient prognosis.nnCitation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5756.

Effect of lapatinib on accumulation of inactive HER2 at the cell membrane and on antibody-dependent cellular cytotoxicity (ADCC) mediated by trastuzumab: A novel mechanism for the enhanced effects of combined anti-HER2 therapy

3594 Background: Lapatinib is a HER2 tyrosine kinase inhibitor that has clinical activity in HER2 overexpressing (HER2+) breast cancer. In vitro and clinical studies have shown that lapatinib enhan...