Tan, Winston

Abstract Despite the rapid progress in personalized cancer therapy (PCT) for breast cancer, no previous studies have used genomic predictors to choose among multiple chemotherapy regimens. It is unclear that given the current regimens how much PCT can improve the response rate for patients who will receive chemotherapy. In this study, we reanalyzed data from published studies of 1111 breast cancer patients who were treated with neoadjuvant chemotherapies. Those patients were divided into three regimen groups: an anthracycline alone, anthracycline plus paclitaxel, and anthracycline plus docetaxel. We developed a new strategy called PRES (Personalized REgimen Selection) to reassign the optimal regimen to each of the patients. First, a variable selection scheme was developed to identify significant genetic predictors for chemotherapy response. The selected genetic variables were then combined with clinical variables to build random forest models to predict the response of a patient to each regimen using pCR (pathological complete response) as the measure of response. The models were used to assign an optimal regimen to each patient to maximize the chance of pCR. We found that the expected rate of pCR was improved from 21.2% to 39.6% (95% CI: 34.6% - 43.0%). We also found that 31.1% of the patients may have been overtreated and 8.2% patients undertreated. A validation study on 21 cell lines showed that our prediction agrees with their paclitaxel-sensitivity profiles. We performed additional analysis on the Cancer Genome Atlas (TCGA) data and found that 18 of the 19 genes identified are significantly differentially expressed between normal and tumor tissues, and 2 of them, TAF6L and METRN (meteorin), are associated with overall survival. In conclusion, PRES could substantially increase response rates for breast cancer patients who will receive one of the widely-accepted chemotherapy regimens at present. Citation Format: Jinfeng Zhang, Kaixian Yu, Qingxiang Amy Sang, Winston Tan, Mayassa B. Dargham, Jun S. Liu, Ty Lively, Cedric Sheffield. Personalized chemotherapy regimen selection for breast cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2034.

Abstract The addition of trastuzumab to chemotherapy extends survival among patients with HER2+ breast cancer. Prior work showed that trastuzumab and chemotherapy augments HER2 extracellular domain (ECD)-specific antibodies. The current study investigated whether combination therapy induced immune responses beyond HER2-ECD and, importantly, whether those immune responses were associated with survival. Pretreatment and posttreatment sera were obtained from 48 women with metastatic HER2+ breast cancer on NCCTG (now Alliance for Clinical Trials in Oncology) studies, N0337 and N983252. IgG to HER2 intracellular domain (ICD), HER2-ECD, p53, IGFBP2, CEA, and tetanus toxoid were examined. Sera from 25 age-matched controls and 26 surgically resected HER2+ patients were also examined. Prior to therapy, some patients with metastatic disease had elevated antibodies to IGFBP2, p53, HER2-ICD, HER2-ECD, and CEA, but not to tetanus toxin, relative to controls and surgically resected patients. Treatment augmented antibody responses to HER2-ICD in 69% of metastatic patients, which was highly associated with improved progression-free survival (PFS; HR = 0.5, P = 0.0042) and overall survival (OS; HR = 0.7, P = 0.038). Augmented antibody responses to HER2-ICD also correlated (P = 0.03) with increased antibody responses to CEA, IGFBP2, and p53, indicating that treatment induces epitope spreading. Paradoxically, patients who already had high preexisting immunity to HER2-ICD did not respond to therapy with increased antibodies to HER2-ICD and demonstrated poorer PFS (HR = 1.6, P < 0.0001) and OS (HR = 1.4, P = 0.0006). Overall, the findings further demonstrate the importance of the adaptive immune system in the efficacy of trastuzumab-containing regimens. Cancer Res; 76(13); 3702–10. ©2016 AACR.

Abstract Background Intra-tumor heterogeneity is the driving force behind disease progression and metastasis, drug resistance, and relapse in cancer patients. Defining personalized treatment regimens and increasing the arsenal of targeted therapies available will provide the best chance of prolonging survival and finding curative treatments. Recent work by our group and others has shed light on aberrant de novo lipogenesis as a feature of many cancers including kidney, breast, and lung cancer. Of the molecules involved in fatty acid metabolism, stearoyl-CoA desaturase 1 (SCD1) is frequently over-expressed. Targeted inhibition of SCD1 demonstrates a loss of tumor cell viability in a variety of cancer models. While there currently are specific small molecule inhibitors for SCD1 none are under investigation as anti-cancer therapeutics. In order to evaluate the efficacy of SCD1 inhibitors against ccRCC in both a preclinical and eventually a clinical setting we sought to generate unique compounds and test their biological efficacy. Methods Utilizing an innovative in silico approach, we designed new inhibitors for SCD1 via a scaffold hopping approach while searching for different “core” scaffolds. Critical interaction moieties from the chemical R-groups were held fixed, while generated cores were rapidly scanned for best-fit criteria (shape, docking, pharmacophore fit (QSAR)) into our Z-matrix. Following de novo compound generation and synthesis, we implemented iterative analog generation for the top hits. Using this method and diversity of chemical space, we pursued three divergent species of compounds into the nanomolar regime. Biological testing of the novel compounds included high-throughput proliferative-based screening, oleic acid rescue, and evaluation of the endoplasmic stress response. Enzymatic inhibition of SCD1 was evaluated by LC-MS. Preclinical pharmacokinetics was established using a range of doses administered intravenously and orally. Anti-tumor response was evaluated in an ectopic model of renal carcinoma, both as a single agent and in combination with SOC. Results A cohort of potential unique small molecule inhibitors against SCD1 were designed and synthesized. Of these, a select group of compounds demonstrated potent and selective enzyme inhibition and reduced tumor growth in in vitro and in vivo models of ccRCC. These novel inhibitors reliably reproduced activation of ER stress markers, authenticating this biological response as a harbinger for successful abrogation of SCD1 activity. Conclusions We have established an effective, expedited, and economical format for in silico modeling of novel agents based on a scaffold-hopping methodology. Our findings provide compelling evidence supporting the therapeutic benefit of SCD1 inhibitors for clinical use as broad-spectrum anti-tumor agents alone or in combination with SOC. Citation Format: Christina A. Von Roemeling, Thomas R. Caulfield, Derek C. Radisky, Ilah Bok, Laura A. Marlow, James Miller, Mojda Sidiqi, Anthony B. Pinkerton, Winston W. Tan, Amy L. Lane, Han W. Tun, John A. Copland. Accelerated drug discovery platform yields synthesis of novel stearoyl-CoA desaturase 1 inhibitors that demonstrate anti-tumor efficacy in several models of aggressive cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4459. doi:10.1158/1538-7445.AM2015-4459

Abstract Introduction: Clear cell renal cell carcinoma (ccRCC) is the most common subtype of RCC, which is the most prevalent kidney cancer among adults. Of the patients who develop this disease, over 1/3 will already present with advanced or metastatic disease during initial diagnosis due to the lack of symptoms in early stages. RCC demonstrates considerable resistance to radiation and traditional chemotherapeutics. Despite advances in the development of targeted anti-cancer treatments, no current drug therapy leads to significant improvement in long term survival in patients with advanced disease with the rare exception of those who respond to immunotherapy. Additionally, patients inevitably develop drug resistance. Therefore new molecular targets for therapy are sorely needed. Our group has identified stearoyl coA desaturase (SCD1) as a novel molecular target in ccRCC. We examined its role in tumor cell growth and viability in vitro and in vivo independently as well as in combination with current FDA approved regimens. Methods: Patient normal and ccRCC tissue samples and cell lines were examined for SCD1 expression. Genetic knockdown models and targeted inhibition of SCD1 through use of a small molecule inhibitor were analyzed for growth, apoptosis, and alterations in gene expression using gene array analysis. Therapeutic models of synergy were evaluated utilizing pharmacologic inhibition of SCD1 with the tyrosine kinase inhibitors (TKI) sunitinib and pazopanib, and the mTOR inhibitor temsirolimus. Results: Our studies identify increased SCD1 expression in all stages of ccRCC. Both genetic knockdown and pharmacologic inhibition of SCD1 decrease tumor cell proliferation and induce apoptosis in vitro and in vivo. Upon gene array, quantitative real-time PCR, and protein analysis of SCDi treated or SCD1 lentiviral knockdown samples, induction of endoplasmic reticulum (ER) stress response signaling was observed, providing mechanistic insight for SCD1 activity in ccRCC. Furthermore, combinatorial application of SCDi with temsirolimus synergistically inhibits tumor growth in vitro and in vivo. Conclusions: Increased SCD1 expression supports ccRCC viability and therefore we propose it as a novel molecular target for therapy either independently or in combination with an mTOR inhibitor for patients whose disease cannot be remedied with surgical intervention, such as in cases of advanced or metastatic disease. These findings support the further evaluation of targeting SCD1 as an anti-cancer strategy in a phase I clinical trial. Citation Format: Christina A. von Roemeling, Laura Marlow, Thomas Caulfield, Kevin Wu, Winston Tan, Han Tun, John A. Copland, Adam Mathias, Chuck Harrison, Louis Dawson, Beth Hollister. Stearoyl-CoA desaturase 1 is a novel molecular therapeutic target for clear cell renal cell carcinoma. [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-210. doi:10.1158/1538-7445.AM2013-LB-210

Renal leiomyosarcoma is a very rare tumor that clinically and radiographically mimics more common renal malignancies. The infrequency of the condition makes it very difficult to diagnose. A 70-year-old male smoker presented with months of hematuria, right-sided flank pain, and weight loss. Imaging revealed a 3.8-centimeter renal mass that had characteristics similar to renal cell carcinoma. Initial biopsy of the mass was negative for malignancy. Two months later, subsequent imaging revealed what appeared to be metastatic bone lesions. Again, a biopsy of one of the lesions was negative for malignancy. Subsequent ureteral pyeloscopy, ureteroscopic renal pelvis biopsy, and brush cytology were negative for malignancy as well. The decision was made to perform nephrectomy for the removal of the mass. Pathologic analysis revealed renal leiomyosarcoma. This case illustrates the difficulty in diagnosing renal leiomyosarcoma. Repeated pathologic sampling was negative because of the tumor heterogeneity. Prompt diagnosis and treatment are very significant as surgical resection at an early stage offers the best prognosis.

Objective: To summarize the pharmacology, development, and clinical application of sorafenib, a specific tyrosine kinase and vascular growth factor inhibitor, for the treatment of renal cell carcinoma (RCC). Data Sources: Clinical literature, including both primary studies and review articles, was obtained by searching MEDLINE (1966–May 2006), using the search terms BAY 43-9006, sorafenib, renal cell carcinoma, and tyrosine kinase inhibitor. Additional information was supplied by the manufacturer, Bayer HealthCare Pharmaceuticals. Study Selection and Data Extraction: Review articles, abstracts, and clinical studies related to sorafenib were analyzed. An evaluation of the research exploring sorafenib as a potential therapy for RCC was conducted. Relevant information was then selected and is reviewed in this article. Data Synthesis: Knowledge of the cellular abnormalities that can cause solid tumors has led to the development of medications that block these pathways. Sorafenib is an oral tyrosine kinase inhibitor that both blocks the Raf kinase pathway and inhibits vascular growth factors. Phase I and II trials have demonstrated that sorafenib has activity against RCC. Dermatologic reactions (rash, desquamation), fatigue, and hypertension have been the most commonly seen treatment-related adverse events. Sorafenib received FDA approval in December 2005 for treatment of advanced RCC. Conclusions: Sorafenib is a novel oral tyrosine kinase inhibitor effective in the treatment of RCC.

Abstract Purpose: We set out to identify Stearoyl-CoA desaturase 1 (SCD1) as a novel molecular target in clear cell renal cell carcinoma (ccRCC) and examine its role in tumor cell growth and viability in vitro and in vivo independently as well as in combination with current U.S. Food and Drug Administration (FDA)-approved regimens. Experimental Design: Patient normal and ccRCC tissue samples and cell lines were examined for SCD1 expression. Genetic knockdown models and targeted inhibition of SCD1 through use of a small molecule inhibitor, A939572, were analyzed for growth, apoptosis, and alterations in gene expression using gene array analysis. Therapeutic models of synergy were evaluated utilizing pharmacologic inhibition of SCD1 with the tyrosine kinase inhibitors (TKI) sunitinib and pazopanib, and the mTOR inhibitor temsirolimus. Results: Our studies identify increased SCD1 expression in all stages of ccRCC. Both genetic knockdown and pharmacologic inhibition of SCD1 decreased tumor cell proliferation and induced apoptosis in vitro and in vivo. Upon gene array, quantitative real-time PCR, and protein analysis of A939572-treated or SCD1 lentiviral knockdown samples, induction of endoplasmic reticulum stress response signaling was observed, providing mechanistic insight for SCD1 activity in ccRCC. Furthermore, combinatorial application of A939572 with temsirolimus synergistically inhibited tumor growth in vitro and in vivo. Conclusions: Increased SCD1 expression supports ccRCC viability and therefore we propose it as a novel molecular target for therapy either independently or in combination with an mTOR inhibitor for patients whose disease cannot be remedied with surgical intervention, such as in cases of advanced or metastatic disease. Clin Cancer Res; 19(9); 2368–80. ©2013 AACR.

No single therapy benefits the majority of patients in the practice of oncology as responses differ even among patients with similar tumor types. The variety of response to therapy witnessed while treating our patients supports the concept of personalized medicine using patients' genomic and biologic information and their clinical characteristics to make informed decisions about their treatment. Personalized medicine relies on identification and confirmation of biologic targets and development of agents to target them. These targeted agents tend to focus on subsets of patients and provide improved clinical outcomes. The continued success of personalized medicine will depend on the expedited development of new agents from proof of concept to confirmation of clinical efficacy.

Abstract Background: Treatment of aromatase refractory metastatic breast cancer (MBC) is difficult and challenging. Estrogen receptor (ER) resistance causes enhanced expression of the vascular endothelial growth factor (VEGF).Several studies have shown that the ER interacts with the VEGF pathway and is an important mechanism of resistance. Therefore we embarked on a phase II study of fulvestrant, a complete ER suppressor and bevacizumab, a well studied VEGF monoclonal antibody in aromatase refractory MBC patients. Methods: A single stage phase II study with an interim analysis of fulvestrant and bevacizumab was conducted with these objectives: 6 month progression-free survival rate (PFS), tumor response, toxicity, and overall survival. Regimen: fulvestrant 250 mg day1 and 15 (cycle 1) then day 1 (cycle 2 and beyond) and bevacizumab 10mg/kg days 1 and 15 of each 4 weeks is a cycle. Results: At the time of interim analysis, 11/20 evaluable patients achieved 3-month progression-free survival status while remaining on treatment for at least 3 months, not meeting the protocol specified efficacy requirements and thus halting accrual. 36 patients were enrolled from September 2007-December 2008; 33 patients were evaluable. Number of prior metastatic chemotherapy regimens: 0 in 26 patients and 1 in 7 patients. 22 (67%) patients received prior hormonal therapy in the metastatic setting. 18 (55%) had measurable disease. A median of 6 cycles (range 1-19) were administered. 12/33 evaluable patients (95% CI:20-55%) achieved 6-month progression-free survival status while remaining on treatment for a least 6 months. Among 18 patients with measurable disease, 2 (11%) patients CI:1.4-35%) had a confirmed tumor reponse (both PR). Additionally, 2 patients had stable disease for greater than 6 months, for a clinical benefit rate of 22%. Median follow up was 8.5 months (range 1.7-17.5 months). Median progression-free survival was 6.2 months (95% CI:5.4-10.1 months). The 6 -month overall survival rate was 84.8% (95% CI 73.5-98%). The median dose level administered was 250 mg for fulvestrant and 10 mg/kg for bevacizumab for cycles 1-19. The most common grade 3/4 adverse events (AEs) were hypertension 2 (6%), headache pain 2 (6%), and confusion 2 (6%). There was 1 grade 5 central nervous system hemorrhage. 13 (39%) patients experienced a grade 3 non-hematologic AE and 4 (12%) experience a grade 4+ non-hematologic AE. Conclusion: Fulvestrant/bevacizumab is safe and tolerable. Although this regimen did not meet its statistical endpoint, 22% of evaluable patients with aromatase refractory diesease achieved clinical benefit with minimal toxicity. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4096.

Abstract Abstract #4020 Background: HER2 positive (HER2+) breast cancer accounts for 20% of all breast cancer and is an independent adverse prognostic factor. Breast magnetic resonance imaging (MRI) has been shown to identify additional mammographically occult ipsilateral (I/L) and contralateral (C/L) disease, however indications for preoperative MRI in patients with newly diagnosed breast cancer are not standardized. While invasive lobular cancer, younger patient age, and increased breast density have been suggested as routine indications, the role of preoperative MRI according to HER2 status has not been evaluated.
 Methods: All patients with invasive breast cancer who underwent preoperative MRI between January 2003 and December 2007 were reviewed. Retrospective chart review was performed to collect clinical, radiographic, and pathologic data. The incidence of additional I/L or C/L malignacy was calculated. Additionally, changes in surgical management because of MRI findings were recorded.
 Results: Of the 401 women with invasive breast cancer undergoing preoperative breast MRI, 51 (13%) had HER2+ tumors. The average age at the time of MRI was similar in both groups. HER2+ patients were more likely to have nodal disease, and tumors with higher rates of lymphovascular invasion or extensive intraductal components.
 
 When compared to HER2- patients, more HER2+ patients had additional ipsilateral MRI abnormalities. A second ipsilateral cancer was found in 31% of HER2+ patients compared to 25% of HER2- patients. When analyzed according to ER status, HER2+/ ER- patients were more likely to have an additional site of cancer compared to HER2+/ER+ patients (42% vs 23%). Conversely, among HER2- patients, rates of additional ipsilateral cancer were similar for HER2-/ER+ (26%) and HERr2-/ER- (23%) patients. Of the 216 patients (HER2+ and HER2-) with additional ipsilateral MRI findings (benign or malignant), 125/216 (58%) patients were deemed appropriate breast conservation (BCT) candidates after MRI. However, BCT was only chosen in 84/125 (67%) patients. Additional contralateral disease was documented in 8% of HER2+ versus 5% of HER2- patients.
 Conclusions: HER2 positivity remains and important prognostic factor for women with breast cancer. Indications for routine preoperative MRI are unclear. In patients with newly diagnosed Her2+ invasive breast cancer routine preoperative MRI may be valuable in the subset of patients who are also ER-. Further study is needed to determine the influence of MRI on patient decisions for surgical therapy. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 4020.