Aline Mamo

The Estrogen Receptor Cofactor SPEN Functions as a Tumor Suppressor and Candidate Biomarker of Drug Responsiveness in Hormone-Dependent Breast Cancers

The treatment of breast cancer has benefitted tremendously from the generation of estrogen receptor-α (ERα)-targeted therapies, but disease relapse continues to pose a challenge due to intrinsic or acquired drug resistance. In an effort to delineate potential predictive biomarkers of therapy responsiveness, multiple groups have identified several uncharacterized cofactors and interacting partners of ERα, including Split Ends (SPEN), a transcriptional corepressor. Here, we demonstrate a role for SPEN in ERα-expressing breast cancers. SPEN nonsense mutations were detectable in the ERα-expressing breast cancer cell line T47D and corresponded to undetectable protein levels. Further analysis of 101 primary breast tumors revealed that 23% displayed loss of heterozygosity at the SPEN locus and that 3% to 4% harbored somatically acquired mutations. A combination of in vitro and in vivo functional assays with microarray-based pathway analyses showed that SPEN functions as a tumor suppressor to regulate cell proliferation, tumor growth, and survival. We also found that SPEN binds ERα in a ligand-independent manner and negatively regulates the transcription of ERα targets. Moreover, we demonstrate that SPEN overexpression sensitizes hormone receptor-positive breast cancer cells to the apoptotic effects of tamoxifen, but has no effect on responsiveness to fulvestrant. Consistent with these findings, two independent datasets revealed that high SPEN protein and RNA expression in ERα-positive breast tumors predicted favorable outcome in patients treated with tamoxifen alone. Together, our data suggest that SPEN is a novel tumor-suppressor gene that may be clinically useful as a predictive biomarker of tamoxifen response in ERα-positive breast cancers.

Real-Life Report on Chemoembolization Using DEBIRI for Liver Metastases from Colorectal Cancer.

Background. Transarterial chemoembolization (TACE) has been investigated in patients with liver metastases from colorectal cancer (LMCRC). Limited experience and available data suggest that TACE can achieve disease stabilization or improvement, even in heavily pretreated patients. Methods. Patients with LMCRC, ECOG 0–2, who failed at least 1 line of systemic chemotherapy, received embolizations with 2 mL of microspheres preloaded with 100 mg of irinotecan. Beads were delivered selectively into hepatic arteries. Primary endpoint was overall survival (OS), analyzed using the Kaplan-Meier method. Secondary endpoint was safety, assessed using CTCAE version 4.0. Results. 27 patients were treated using DEBIRI. Patient median age was 57 years (range was 45–82 years). The median number of total embolizations was 1.3 (range 1–3). The median OS was 5.4 months (95% CI; 1.1–22.7 months). The most reported postembolization events were nausea (8/27), vomiting (6/27), right upper quadrant pain (16/27), fatigue (9/27), and the development of ascites (6/27). 5/26 patients required hospitalization after TACE for severe pain. Hospitalization was also required for 1 case of allergic reaction and 1 case of infection. Conclusion. Our data suggest that TACE with DEBIRI could be efficacious in a palliative setting for patients with LMCRC, but they do not necessarily support routine use in clinical practice.

Quantifying treatment delays in adolescents and young adults with cancer at McGill University

BACKGROUND Since the end of the 1980s, the magnitude of survival prolongation or mortality reduction has not been the same for adolescents and young adults (ayas) with cancer as for their older and younger counterparts. Precise reasons for those observations are unknown, but the differences have been attributed in part to delays in diagnosis and treatment. In 2003 at the Jewish General Hospital, we developed the first Canadian multidisciplinary aya oncology clinic to better serve this unique patient population. The aim of the present study was to develop an approach to quantify diagnosis delays in our aya patients and to study survival in relation to the observed delay. METHODS In a retrospective chart review, we collected information about delays, treatment efficacy, and obstacles to treatment for patients seen at our aya clinic. RESULTS From symptom onset, median time to first health care contact was longer for girls and young women (62 days) than for boys and young men (6 days). Median time from symptom onset to treatment was 173 days; time from first health care contact to diagnosis was the largest contributor to that duration. Delays in diagnosis were shorter for patients who initially presented to the emergency room, but compared with patients whose first health contact was of another type, patients presenting to the emergency room were 3 times more likely to die from their disease. CONCLUSIONS Delays in diagnosis are frequently reported in ayas with cancer, but the duration of the delay was unrelated to survival in our sample. Application of this approach to larger prospective samples is warranted to better understand the relation between treatment delay and survival in ayas-and in other cancer patient groups.

Retrospective analysis of the effect of CAPOX and mFOLFOX6 dose intensity on survival in colorectal patients in the adjuvant setting

BACKGROUND Despite lack of a true comparative study, the folfox (5-fluorouracil-leucovorin-oxaliplatin) and capox (capecitabine-oxaliplatin) regimens are believed to be similar in their efficacy and tolerability in the treatment of stage iii colorectal cancer. However, that belief has been disputed, because real-life data suggest that the capox regimen is more toxic, leading to more frequent reductions in the delivered dose intensity-thus raising questions about the effect of dose intensity on clinical outcomes. METHODS A retrospective data review for two Canadian institutions, the Segal Cancer Centre and the Tom Baker Cancer Centre, considered patients diagnosed with stage iii colorectal cancer during 2006-2013. Primary endpoints were dose intensity and toxicity, with a secondary endpoint of disease-free survival. RESULTS The study enrolled 180 eligible patients (80 at the Segal Cancer Centre, 100 at the Tom Baker Cancer Centre). Of those 180 patients, 75 received capox, and 105 received mfolfox6. In the capox group, a significant dose reduction was identified for capecitabine compared with 5-fluorouracil in mfolfox6 group (p = 0.0014). Similarly, a significant dose reduction was observed for oxaliplatin in mfolfox6 compared with oxaliplatin in capox (p = 0.0001). Compared with the patients receiving capox, those receiving mfolfox6 were twice as likely to experience a treatment delay of more than 1 cycle-length (p = 0.03855). Toxicity was more frequent in patients receiving mfolfox6 (nausea: 30% vs. 18%; diarrhea: 47% vs. 24%; peripheral sensory neuropathy: 32% vs. 3%). At a median follow-up of 40 months, preliminary data showed no difference in disease-free survival (p = 0.598). Pooled data from both institutions were also separately analyzed, and no significant differences were found. CONCLUSIONS Our results support the use of capox despite a lack of head-to-head randomized trial data.

Abstract LB-47: SPEN is a novel candidate tumor suppressor gene that regulates response to tamoxifen in estrogen receptor positive breast cancers.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC The majority of breast cancers are hormone-responsive and are treated with anti-estrogens, such as tamoxifen. However, most of the 30 and 50% of estrogen receptor positive (ER+) patients that initially respond to tamoxifen eventually become resistant to the drug. Although there are several mechanisms responsible for resistance of breast cancers to tamoxifen, no predictive biomarkers for tamoxifen resistance are in clinical use besides the estrogen receptor (ER) and the progesterone receptors (PR). Using a novel integrative genomic method based on the discovery of nonsense mutations in deleted chromosomal fragments, we identified a nonsense mutation in the SPEN gene in the T47D breast cancer cell line. SPEN is a transcriptional repressor of the estrogen-signaling pathway, which is recruited to estrogen-responsive elements upon activation of the ER. We found 4 somatic mutations (2 nonsense and 2 missense) in 23 breast tumors showing loss of heterozygosity at the SPEN locus. Moreover, tissue microarrays showed that SPEN was frequently over-expressed in the nucleus of normal breast epithelial cells, but in only 10% of breast tumor cells, suggesting that inactivation of SPEN in breast cancer contributes to disease progression. In vitro, overexpression of SPEN in the T47D breast cancer cell line, in which SPEN is mutated and endogenous levels of the protein are very low, resulted in significantly decreased cell proliferation and anchorage-independent growth, decreased PR expression as well as increased sensitivity to tamoxifen. Remarkably, tamoxifen treatment induced 5-fold higher levels of apoptosis in SPEN-overexpressing compared to control T47D cells. In addition, using a tissue microarray of 100 tumor samples from ER+ breast cancer patients treated with tamoxifen only, we found that patients whose tumors express high levels of SPEN had a much better prognosis than patients whose tumors express low or no levels of the protein. To identify transcriptional targets of SPEN besides the PR, we performed gene expression profiling on a panel of breast cancer cell lines in which SPEN was either overexpressed or knocked-down. We found an inverse relationship between SPEN and Apolipoprotein D (APOD) expression, suggesting that SPEN potently repressed transcription of the APOD gene. APOD encodes a glycoprotein from the lipocalin family, which can chelate multiple molecules including progesterone, arachidonic acid as well as tamoxifen itself. Hence, our analysis shows that the loss or mutation of SPEN in ER+ breast cancers has the potential to affect tumor growth as well as sensitivity to tamoxifen, in part through upregulation of APOD expression. Together, our results highlight the role of SPEN as a novel putative tumor suppressor gene in breast cancer and suggest that SPEN is a candidate predictive biomarker of tamoxifen resistance in ER+ breast cancer patients. Citation Format: Stephanie Legare, Luca Cavallone, Aline Mamo, Catherine Chabot, Dana Keilty, Anthony Magliocco, Alexander Klimowicz, Patricia Tonin, Mark Basik. SPEN is a novel candidate tumor suppressor gene that regulates response to tamoxifen in estrogen receptor positive breast cancers. [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-47. doi:10.1158/1538-7445.AM2013-LB-47