Oxylipins as Biomarkers for Aromatase Inhibitor-Induced Arthralgia (AIA) in Breast Cancer Patients

Aromatase inhibitor-induced arthralgia (AIA) presents a major problem for patients with breast cancer but is poorly understood. This prospective study explored the inflammatory metabolomic changes in the development of AIA. This single-arm, prospective clinical trial enrolled 28 postmenopausal women with early-stage (0-3) ER+ breast cancer starting adjuvant anastrozole. Patients completed the Breast Cancer Prevention Trial (BCPT) Symptom Checklist and the Western Ontario and McMaster Universities Arthritis Index (WOMAC) at 0, 3, and 6 months. The plasma levels of four polyunsaturated fatty acids (PUFAs) and 48 oxylipins were quantified at each timepoint. The subscores for WOMAC-pain and stiffness as well as BCPT-total, hot flash, and musculoskeletal pain significantly increased from baseline to 6 months (all p < 0.05). PUFA and oxylipin levels were stable over time. The baseline levels of 8-HETE were positively associated with worsening BCPT-total, BCPT-hot flash, BCPT-musculoskeletal pain, WOMAC-pain, and WOMAC- stiffness at 6 months (all p < 0.05). Both 9-HOTrE and 13(S)-HOTrE were related to worsening hot flash, and 5-HETE was related to worsening stiffness (all p < 0.05). This is the first study to prospectively characterize oxylipin and PUFA levels in patients with breast cancer starting adjuvant anastrozole. The oxylipin 8-HETE should be investigated further as a potential biomarker for AIA.

Abstract P1-05-04: Physician Practice Patterns of Breast Imaging After Treatment: Survey of Real-World Practice

Introduction: Mammography is the cornerstone of breast cancer screening, diagnosis, and surveillance. After definitive treatment for breast cancer, mammograms are continued for surveillance. The current recommendations regarding surveillance after definitive treatment (surgery and radiation) lack consensus amongst various societies. There are no clear guidelines in regards to the type of mammogram recommended: diagnostic or screening mammogram or if a diagnostic mammogram is used, when to return to routine screening protocols. Current practice patterns are driven by physician’s preference. We conducted a survey to evaluate physicians’ preferences in ordering breast imaging post- breast cancer diagnosis and treatment. Methods: This survey was approved by University of Arizona institutional review board. This survey was conducted through American Society of Clinical Oncology (ASCO) voluntary opt-in Research Survey Pool (RSP). ASCO sent out this survey to 1000 randomly selected members between 10/19/2021-11/22/2021. Weekly reminders to participate were sent through the ASCO RSP for 5 weeks. Participants clicked the link to the survey platform where upon consent they completed the survey. Results: The survey was completed by 244 healthcare professionals through the ASCO RSP. Most respondents were physicians (n=228), primarily medical oncologists (n=174) and practiced in an academic environment in the United States (n=132). After definitive treatment, majority (58%) ordered first imaging at 6 months post-surgery/radiation, and it was primarily a diagnostic mammogram (68%). Interestingly, for patients at age 80 or above, screening mammogram was used for surveillance after definitive treatment by most respondents (59%). After first post-surgery/radiation mammogram there is an almost even spilt (50%) on continuing with diagnostic versus screening mammograms for follow up. Of those who order diagnostic mammograms, majority (38%) do it for 3-5 years with an additional 30% continuing it beyond 5 years. Almost 65% of respondents reported they do not stop screening mammograms at any age for patients with a history of early-stage breast cancer as long as they are healthy. Conclusions: The practice patterns of healthcare professionals as it relates to the type and frequency of breast imaging varies significantly. Despite having the same imaging quality there is a significant difference in the cost of screening and diagnostic mammograms. In addition, in clinical practice, most routine screening care is covered by insurances without co-pays or out of pocket costs for patients. Diagnostic imaging does not fall under routine screening care and frequently requires out of pocket expenses for patients. As insurance companies start to decline certain imaging modalities used for cancer detection due to lack of data supporting the use of these expensive studies, specific imaging guidelines for follow up in post-treatment setting for patients with breast cancer are needed.

Citation Format: Meredith Whittaker, Kiah Farr, Preethika Potluri, Nova Foster, Jennifer Erdrich, Jennifer Segar, Sima Ehsani, Sao Jiralerspong, Denise Roe, Pavani Chalasani. Physician Practice Patterns of Breast Imaging After Treatment: Survey of Real-World Practice [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-05-04.

Abstract P4-04-02: Evaluation of Dronabinol to Decrease Opioid Use for Cancer- Induced Bone Pain

Purpose Bone metastases (BM) from breast cancer cause significant complications including pain, hypercalcemia, spinal cord compression, and pathologic fractures, collectively referred to as skeletal related events (SREs). Of all SREs, bone pain impacts the quality of life (QOL) most significantly. Cancer- induced bone pain (CIBP) is difficult to treat with limited treatment options and requires a multimodal approach. Management of CIBP is primarily by opioids which have notable side effects like sedation, constipation, and concern for addiction. In addition, pre-clinical evidence suggests that opioids accelerate bone loss and increase risk of fractures. There is an unmet need for novel analgesic therapy interventions to optimize QOL for patients with BM from metastatic breast cancer. Preclinical studies have shown that the endogenous cannabinoid (CB) system is involved in pain modulation, bone regulation, immunity, and restraint of cancer pathogenesis. CB2 receptor activation has been shown to inhibit proinflammatory cytokines/chemokines in pre-clinical models. Treatment with selective CB2 agonist in mice with BM led to significant antinociception, decreased cancer-induced bone degradation, and reduced side effects of morphine. In addition to alleviating pain, CB2 agonists were shown to enhance bone growth/strength in these mice. Based on this pre-clinical data, we hypothesized that the addition of a CB2 agonist will improve pain symptoms and decrease opioid requirement in patients with bone metastases from breast cancer. We proceeded to conduct a pilot study by repurposing a clinically approved CB2/CB1 agonist, dronabinol. Methods We conducted a prospective, single site study among patients with BM from breast cancer at our center (NCT03661892). Patients had to have been on opioids for CIBP for at least 4 weeks and not using marijuana or CBD products. Patients were treated with 10mg dronabinol BID for 8 weeks. Our primary objective was to determine the proportion who decrease their opioid use by ≥ 20%. The null hypothesis value was 5% of women would have a 20% decrease. With 14 participants, we could detect an increase from 5% to 29% (n=4) with 80% statistical power using a one-sided alpha level of 0.05. Participants completed Brief Pain Inventory and the European Organization for Research and Treatment of Cancer quality of life questionnaires pre and post treatment. Results Twenty participants consented with 14 patients completing the study and evaluable for primary analysis. No patients received any palliative radiation therapy or other therapies for bone pain within 3 months prior to enrollment to this study. Four patients decreased their opioid use by ≥ 20% meeting the primary objective. Patients reported significant improvement in pain severity, interference scores, quality of life and insomnia based on the questionnaires. There were no grade 4 side effects and only 1 patient had grade 3 adverse event (dizziness) related to study drug. Of the 14 patients who completed the study, 9 desired to continue dronabinol therapy after completion. Conclusion Our pilot study shows that the addition of dronabinol resulted in decreased opioid requirements for CIBP in patients with metastatic breast cancer. Patient-reported outcomes also demonstrated improved pain and QOL with the addition of dronabinol. While we did not see any significant AEs tolerability may be of concern due to CB1 psychoactive effects. Our results are promising and warrant further investigation into evaluating CB2 agonists for improved pain control from CIBP and to decrease opioid use.

Citation Format: Jennifer Segar, Kiah Farr, Mary Junak, Denise Roe, Sima Ehsani, Sao Jiralerspong, Ibrahim Mohab, Todd Vanderah, Pavani Chalasani. Evaluation of Dronabinol to Decrease Opioid Use for Cancer- Induced Bone Pain [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-04-02.

Investigating keratinocyte growth factor hair serum for the prevention of chemotherapy-induced alopecia

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Background: Chemotherapy induced alopecia (CIA) is known to have a significant psychological and quality of life impact, mainly in women. While cold caps have been shown to decrease CIA, expense, availability, and extension of treatment durations are barriers for routine clinical use. Keratinocyte Growth Factor (KGF) has been shown to have cytoprotective effects on human keratinocytes in vitro and reduce apoptosis in human hair follicles. Based on this data, we hypothesized that KGF-Hair serum (KGF-HS) will prevent CIA in women undergoing chemotherapy as treatment for breast cancer. Methods: We designed a Simon 2-stage prospective study to test our hypothesis. Study was approved by our institutional review board and registered on clinicaltrials.gov (NCT04554732). In part 1 we planned to enroll 20 patients into a single arm. If ≥ 4 responses are noted, we proposed to initiate part 2: randomized double-blind placebo-controlled study. Patients with early-stage breast cancer (ESBC) who were scheduled to get at least 4 cycles of anthracycline or taxane based chemotherapy were included. Patients with inflammatory scalp conditions, hair loss disorder, scalp disorders were excluded. The primary endpoint was successful hair preservation using the Common Terminology Criteria for Adverse Events 4.0 scale at the end of 4 cycles of chemotherapy. Secondary end points included wig use and scores on the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire–Core 30, Hospital Anxiety and Depression Scale, and a summary scale of the Body Image Scale. Results: Twenty patients completed part 1 of the study and were evaluable for primary endpoint. Mean age was 60 years and 70% were treated with taxane based chemotherapy. Successful hair preservation was noted in 0 of 20 women. Mean duration of treatment with KGF-HS was 4.6wks (range 2-10 weeks) before women came off study due to grade 2 hair loss. There were no statistically significant differences in changes in any of the scales of quality of life from baseline to end of treatment. There were only 2 grade 1 events (1 rash and 1 itching) reported which resolved after coming off the KGF-HS. There were no serious adverse device events. Conclusions: Among women with early-stage breast cancer receiving chemotherapy with a taxane, anthracycline, or both, using KGF-HS did not prevent CIA. Further research is needed to investigated other novel topical options to prevent CIA. Clinical trial information: NCT04554732.

Metformin and an insulin/IGF-1 receptor inhibitor are synergistic in blocking growth of triple-negative breast cancer

PURPOSE

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer with poor survival outcomes. Metformin has been shown to have antitumor effects by lowering serum levels of the mitogen insulin and having pleiotropic effects on cancer cell signaling pathways. BMS-754807 is a potent and reversible inhibitor of both insulin-like growth factor 1 receptor (IGF-1R) and insulin receptor (IR). Both drugs have been reported to have some efficacy in TNBC. However, it is unclear whether the combination of the two drugs is more effective than single drug treatment in TNBC.

METHODS

We treated a panel of TNBC cell lines with metformin and BMS-754807 alone and in combination and tested cell viability using MTS assays. We used the CompuSyn software to analyze for additivity, synergism, or antagonism. We also examined the molecular mechanism by performing reverse phase protein assay (RPPA) to detect the candidate pathways altered by single drugs and the drug combination and used Western blotting to verify and expand the findings.

RESULTS

The combination of metformin and BMS-754807 showed synergy in 11 out of 13 TNBC cell lines tested (85%). RPPA analysis detected significant alterations by the drug combination of multiple proteins known to regulate cell cycle and tumor growth. In particular, the drug combination significantly increased levels of total and phosphorylated forms of the cell cycle inhibitor p27^Kip1 and decreased the level of the p27^Kip1 E3 ligase SCF^Skp2.

CONCLUSIONS

We conclude that the combination of metformin and BMS-754807 is more effective than either drug alone in inhibiting cell proliferation in the majority of TNBC cell lines, and that one important mechanism may be suppression of SCF^Skp2 and subsequent stabilization of the cell cycle inhibitor p27^Kip1. This combination treatment may represent an effective targeted therapy for a significant subset of TNBC cases and should be further evaluated.

TBCRC023: A Randomized Phase II Neoadjuvant Trial of Lapatinib Plus Trastuzumab Without Chemotherapy for 12 versus 24 Weeks in Patients with HER2-Positive Breast Cancer

PURPOSE

Prior neoadjuvant trials with 12 weeks of dual anti-HER2 therapy without chemotherapy demonstrated a meaningful pathologic complete response (pCR) in patients with HER2-positive breast cancer. In this trial, we sought to determine whether longer treatment would increase the rate of pCR.

PATIENTS AND METHODS

TBCRC023 (NCT00999804) is a randomized phase II trial combining a Simon phase II design in the experimental arm with a pick-the-winner design, not powered for direct comparison. Women with HER2-positive breast tumors measuring ≥2 cm (median = 5 cm) were randomized in a 1:2 ratio to 12 versus 24 weeks of lapatinib and trastuzumab. Letrozole (along with ovarian suppression if premenopausal) was administered in patients whose tumors were also estrogen receptor (ER) positive. All evaluable patients were assessed for in-breast pCR.

RESULTS

Ninety-seven patients were enrolled (33 in 12-week arm and 64 in 24-week arm), of whom 94 were evaluable. Median age was 51 years, and 55% were postmenopausal. Median tumor size was 5 cm, and 65% were ER-positive. The rate of pCR in the 24-week arm was 28% and numerically superior to the 12-week arm (12%). This was driven by increased pCR in the ER-positive subgroup (33% vs. 9%). Study treatment was well tolerated, with grade 1-2 diarrhea and acneiform rash being the most common toxicities.

CONCLUSIONS

Treatment with dual anti-HER2 therapy for 24 weeks led to a numeric increase in pCR rate in women with HER2-positive breast cancer, without using chemotherapy. If validated, this approach may help identify patients who may benefit from deescalation of therapy.

Randomized controlled trial of high-dose versus standard-dose vitamin D3 for prevention of aromatase inhibitor-induced arthralgia

PURPOSE

Half of hormone receptor-positive (HR+) breast cancer patients will develop joint pain, termed aromatase inhibitor-induced arthralgia (AIA), while taking aromatase inhibitor therapy. Though there is no universally accepted effective treatment for AIA, there has been some evidence to support high-dose vitamin D as a treatment.

METHODS

We randomized post-menopausal women who were beginning adjuvant AI therapy to receive standard-dose vitamin D3 (800 IU daily for 52 weeks), or high-dose vitamin D3 (50,000 IU weekly for 12 weeks, followed by 2000 IU daily for 40 weeks). The primary end point was development of AIA. The trial was designed to enroll 184 patients. This futility analysis was performed after 93 patients were enrolled.

RESULTS

The high-dose vitamin D regimen was effective in raising serum vitamin D levels, but there was no significant difference in development of AIA between the two arms. In the high-dose arm, 25 patients (54%) developed AIA, compared to 27 patients (57%) in the standard-dose arm. The planned futility analysis was positive; thus, the study was terminated. Neither baseline vitamin D nor 12-week vitamin D level was predictive of AIA development.

CONCLUSION

Although vitamin D levels were increased in the high-dose arm, there was no significant signal for benefit of high-dose vitamin D supplementation for AIA prevention in this unblinded trial. This study, along with several others, implies that vitamin D likely does not play a significant role in AIA for the majority of patients.

Abstract PD6-02: A randomized, controlled trial of high dose vs. standard dose vitamin D for aromatase inhibitor-induced arthralgia in breast cancer survivors

Background: Approximately half of women on aromatase inihbitor (AI) therapy develop AI-induced arthralgia (AIA), and many discontinue the medication because of this common side effect. While Vitamin D has been studied as a treatment for AIA, trial results have been conflicting thus far.

Patients and Methods: All subjects were post menopausal women who were beginning adjuvant AI therapy for stage I-III hormone receptor positive breast cancer. Patients were randomized 1:1 to receive standard dose vitamin D3 (800 IU daily for 52 weeks) or high dose vitamin D3 (50,000 IU weekly for 12 weeks, followed by 2000 IU daily for 40 weeks). All patients also took oral calcium 600 mg daily. The primary endpoint was development of AIA, as defined by pre-specified changes in the Health Assessment Questionnaire II (HAQ-II). Secondary endpoints include compliance with AI therapy, and correlation between grip strength and development of AIA. Exploratory endpoint was measurement of inflammatory cytokine reduction in each arm. The trial was designed to enroll 184 patients, but this futility analysis was performed after 93 patients were enrolled. The futility boundary for stopping the trial early was calculated as p = 0.47.

Results: All 93 patients (46 in the high dose arm, and 47 in the standard dose arm) enrolled in the study at the time of the interim analysis were evaluable. The HAQ-II was completed at 12 weeks in 76% on the high dose arm, and 68% in the standard dose arm. Subjects who did not complete the questionnaire were deemed as study failures (i.e. development of AIA was assumed). In the high dose arm, 25 patients (54%) developed AIA, compared to 27 patients (57%) in the standard dose arm. The one-tailed p value is 0.3818, and the Z-score is 0.3, yielding only a 38% conditional power that that study would find a significant difference between the two arms. Thus, the study was terminated early for futility. There was no significant difference between the two arms in adherence to AI therapy. The grip strength and inflammatory cytokine data are pending at this time. They will be ready by the time of the conference.

Conclusions: There was no significant signal for benefit of high dose vitamin D supplementation, as compared to standard dose vitamin D, for AIA prevention in post menopausal women taking adjuvant AI therapy. These results further characterize the role of Vitamin D in AIA, and they inform future clinical trials in this arena. Further research is necessary, as this remains an important cause of non-adherence to this highly effective therapy.

Citation Format: Niravath P, Wang T, Hilsenbeck SG, Lipscomb K, Pavlick A, Jiralerspong S, Nangia J, Ellis M, Ademuyiwa F, Cherian M, Frith A, Ma C, Park H, Rigden C, Suresh R, Osborne CK, Rimawi MF. A randomized, controlled trial of high dose vs. standard dose vitamin D for aromatase inhibitor-induced arthralgia in breast cancer survivors [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD6-02.

Unbiased Lipidomic Profiling of Triple-Negative Breast Cancer Tissues Reveals the Association of Sphingomyelin Levels with Patient Disease-Free Survival

The reprogramming of lipid metabolism is a hallmark of many cancers that has been shown to promote breast cancer progression. While several lipid signatures associated with breast cancer aggressiveness have been identified, a comprehensive lipidomic analysis specifically targeting the triple-negative subtype of breast cancer (TNBC) may be required to identify novel biomarkers and therapeutic targets for this most aggressive subtype of breast cancer that still lacks effective therapies. In this current study, our global LC-MS-based lipidomics platform was able to measure 684 named lipids across 15 lipid classes in 70 TNBC tumors. Multivariate survival analysis found that higher levels of sphingomyelins were significantly associated with better disease-free survival in TNBC patients. Furthermore, analysis of publicly available gene expression datasets identified that decreased production of ceramides and increased accumulation of sphingoid base intermediates by metabolic enzymes were associated with better survival outcomes in TNBC patients. Our LC-MS lipidomics profiling of TNBC tumors has, for the first time, identified sphingomyelins as a potential prognostic marker and implicated enzymes involved in sphingolipid metabolism as candidate therapeutic targets that warrant further investigation.

Obesity and Breast Cancer Prognosis: Evidence, Challenges, and Opportunities

Purpose To summarize the evidence of an association between obesity and breast cancer prognosis. Methods We reviewed the literature regarding overweight and obesity and breast cancer survival outcomes, overall and with regard to breast cancer subtypes, breast cancer therapies, biologic mechanisms, and possible interventions. We summarize our findings and provide clinical management recommendations. Results Obesity is associated with a 35% to 40% increased risk of breast cancer recurrence and death and therefore poorer survival outcomes. This is most clearly established for estrogen receptor-positive breast cancer, with the relationship in triple-negative and human epidermal growth factor receptor 2-positive subtypes less well established. A range of biologic mechanisms that may underlie this association has been identified. Weight loss and lifestyle interventions, as well as metformin and other obesity-targeted therapies, are promising avenues that require further study. Conclusion Obesity is associated with inferior survival in breast cancer. Understanding the nature and mechanisms of this effect provides an important opportunity for interventions to improve the diagnosis, treatment, and outcomes of obese patients with breast cancer.

Abstract 1212: Effect of metformin and insulin-/IGF1-receptor inhibitor combination drug therapy in triple negative breast cancer

Background: Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer with poor survival outcomes. Chemotherapy is the only approved treatment, as there are no targeted therapies. Metformin is an anti-diabetic drug for Type 2 Diabetes. It has been shown to have anti-tumor effects by lowering serum levels of the mitogen insulin, and by pleiotropic effects on cancer cell signaling pathways. BMS-754807 is a potent and reversible inhibitor of the insulin receptor (IR)/insulin-like growth factor 1 receptor (IGF-1R) family kinases that has been shown to have activity in a subset of TNBC. The aim of this study is to evaluate the hypothesis that the combination of metformin and BMS-754807 is more effective than single drug treatment in TNBC.

Experimental design and methods: We treated TNBC cell lines with metformin and BMS-754807 alone and in combination and tested cell viability using MTS assays. Then we used CompuSyn software to analyze the dose-effect of drug combinations for additivity, synergism, or antagonism. We also examined the mechanism by performing Western blots of candidate pathways.

Results: 5 out of the 9 cell lines tested (56%) showed synergism of metformin and BMS-754807 in the drug combination assays. Western blots showed significant inhibition of IR/IGF-1R and PI3K/Akt pathways with the drug combination.

Conclusion: We conclude that the combination of metformin and BMS-754807 is more effective than single drug in a significant proportion of triple negative breast cancer cell lines. This combination may represent effective targeted therapy for a subset of TNBC. Further studies to evaluate this possibility are underway.

Citation Format: Lei Xue, Laura Camacho, Sushma Kothapalli, Sao Jiralerspong. Effect of metformin and insulin-/IGF1-receptor inhibitor combination drug therapy in triple negative 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 1212.

Metformin in breast cancer - an evolving mystery

Metformin, a diabetes drug with well-established side effect and safety profiles, has been widely studied for its anti-tumor activities in a number of cancers, including breast cancer. But its mechanism of action in the clinical arena remains elusive. In a window of opportunity trial of metformin in non-diabetic breast cancer patients, Dowling and colleagues examined both the direct actions of the drug on cancer cells (as mediated by AMP kinase), as well as its indirect actions (as mediated by circulating insulin). The data suggest that short-term administration of metformin in this setting has anti-tumor effects significantly involving the indirect, insulin-dependent pathway. The role of the direct pathway remains to be determined. This study represents an important step forward in establishing one of several possible mechanisms for metformin, information that will be useful in determining candidate biomarkers to evaluate in large clinical trials of metformin, such as the ongoing NCIC CTG MA.32 trial of adjuvant metformin. The potential significance of these data for metformin in the treatment of breast cancer is discussed here.

Obesity, diabetes, and survival outcomes in a large cohort of early-stage breast cancer patients

BACKGROUND

To determine the relationship between obesity, diabetes, and survival in a large cohort of breast cancer patients receiving modern chemotherapy and endocrine therapy.

PATIENTS AND METHODS

We identified 6342 patients with stage I-III breast cancer treated between 1996 and 2005. Patients were evaluated according to body mass index (BMI) category and diabetes status.

RESULTS

In a multivariate model adjusted for body mass index, diabetes, medical comorbidities, patient- and tumor-related variables, and adjuvant therapies, relative to the normal weight, hazard ratios (HRs) for recurrence-free survival (RFS), overall survival (OS), and breast cancer-specific survival (BCSS) for the overweight were 1.18 [95% confidence interval (CI) 1.02-1.36], 1.20 (95% CI 1.00-1.42), and 1.21 (95% CI 0.98-1.48), respectively. HRs for RFS, OS, and BCSS for the obese were 1.13 (95% CI 0.98-1.31), 1.24 (95% CI 1.04-1.48), and 1.23 (95% CI 1.00-1.52), respectively. Subset analyses showed these differences were significant for the ER-positive, but not ER-negative or HER2-positive, groups. Relative to nondiabetics, HRs for diabetics for RFS, OS, and BCSS were 1.21 (95% CI 0.98-1.49), 1.39 (95% CI 1.10-1.77), and 1.04 (95% CI 0.75-1.45), respectively.

CONCLUSIONS

In patients receiving modern adjuvant therapies, obesity has a negative impact on RFS, OS, and BCSS; and diabetes has a negative impact on RFS and OS. Control of both may be important to improving survival in obese and diabetic breast cancer patients.

Using whole-exome sequencing to identify inherited causes of autism

Despite significant heritability of autism spectrum disorders (ASDs), their extreme genetic heterogeneity has proven challenging for gene discovery. Studies of primarily simplex families have implicated de novo copy number changes and point mutations, but are not optimally designed to identify inherited risk alleles. We apply whole-exome sequencing (WES) to ASD families enriched for inherited causes due to consanguinity and find familial ASD associated with biallelic mutations in disease genes (AMT, PEX7, SYNE1, VPS13B, PAH, and POMGNT1). At least some of these genes show biallelic mutations in nonconsanguineous families as well. These mutations are often only partially disabling or present atypically, with patients lacking diagnostic features of the Mendelian disorders with which these genes are classically associated. Our study shows the utility of WES for identifying specific genetic conditions not clinically suspected and the importance of partial loss of gene function in ASDs.

P1-08-04: Obesity, Adjuvant Therapy, and Survival Outcomes in Early-Stage Breast Cancer

BACKGROUND: Obesity has risen to epidemic proportions and is associated with worse breast cancer (BC) prognosis in most studies. However, the effects of obesity according to adjuvant therapy choice are largely unknown. To address this issue, we examined the relationship between body mass index (BMI), adjuvant therapy, and survival outcomes in a large cohort of early-stage BC patients.

METHODS: We retrospectively studied patients from the Baylor Breast Center Tumor Bank treated from 1970–1995. Patients were divided into 3 BMI classes: normal/underweight (N, BMI&lt;25), overweight (Ov, BMI 25–30), obese (Ob, BMI≥30); and 4 treatment groups: no adjuvant therapy, chemotherapy (mainly CMF), endocrine therapy (mainly tamoxifen), both chemo- and endocrine therapy. Time-to-recurrence (TTR), disease-free survival (DFS) and overall survival (OS) were estimated by the Kaplan-Meier method and compared among groups via the log-rank test. Multivariate analysis was conducted via Cox proportional hazards models.

RESULTS: There were 4,368 patients. Median age was 58. 74% were postmenopausal. 72% had stage I-II disease, 28% stage III. 76% were estrogen receptor (ER)-positive, 24% ER-negative. Patients distributed into BMI classes as follows: N 48%, Ov 30%, Ob 22%. Higher BMI was associated with postmenopausal status and increasing age, tumor size, positive lymph nodes, and stage, as well as a higher likelihood of receiving treatment. Median follow-up was 5 years. Kaplan-Meier analysis showed that TTR was significantly shorter in the Ov and Ob groups as compared to the N group (p=0.019), due to distant (p=0.001) rather than local (p=0.970) recurrences. DFS was also significantly worse in the Ov and Ob groups (p=0.002), as was OS (p=0.001). The Table shows the hazard ratios for the various survival outcomes after adjustment for age, tumor size, nodal status, and treatment groups. For all patients, TTR, DFS, and OS were significantly worse in the Ob vs. N groups. TTR and DFS were significantly worse in the chemo treated Ob vs. N groups. DFS and OS were significantly better in the endo treated Ov vs. N groups.

DISCUSSION: In this large cohort of BC patients, survival outcomes (TTR, DFS, OS) were significantly worse in the obese group. This remained true after adjustment for multiple factors. Obesity was associated with worse survival outcomes in the chemo treated (CMF) group. Overweight was associated with better survival outcomes in the endo treated (tamoxifen) group. These results confirm and extend the results of previous studies. Further studies to discover the reasons for these differences in outcomes are underway.

Metformin and pathologic complete responses to neoadjuvant chemotherapy in diabetic patients with breast cancer

PURPOSE

Population studies have suggested that metformin use in diabetic patients decreases cancer incidence and mortality. Metformin inhibits the growth of cancer cells in vitro and tumors in vivo. However, there is little clinical data to support this. Our purpose was to determine whether metformin use was associated with a change in pathologic complete response (pCR) rates in diabetic patients with breast cancer receiving neoadjuvant chemotherapy.

PATIENTS AND METHODS

We identified 2,529 patients who received neoadjuvant chemotherapy for early-stage breast cancer between 1990 and 2007. Patients were compared by groups: 68 diabetic patients taking metformin, 87 diabetic patients not taking metformin, and 2,374 nondiabetic patients. pCR rates were compared between the three groups using chi(2) tests of independence and compared pair- wise using a binomial test of proportions. Factors predictive of pCR were assessed using a multivariate logistic regression model.

RESULTS

The rate of pCR was 24% in the metformin group, 8.0% in the nonmetformin group, and 16% in the nondiabetic group (P = .02). Pairwise comparisons between the metformin and nonmetformin groups (P = .007) and the nonmetformin and nondiabetic groups (P = .04) were significant. Comparison of the pCR rates between the metformin and nondiabetic groups trended toward but did not meet significance (P = .10). Metformin use was independently predictive of pCR (odds ratio, 2.95; P = .04) after adjustment for diabetes, body mass index, age, stage, grade, receptor status, and neoadjuvant taxane use.

CONCLUSION

Diabetic patients with breast cancer receiving metformin and neoadjuvant chemotherapy have a higher pCR rate than do diabetics not receiving metformin. Additional studies to evaluate the potential of metformin as an antitumor agent are warranted.

Manganese superoxide dismutase induction by iron is impaired in Friedreich ataxia cells

Iron-mediated oxidative stress has been implicated in the pathology of the neurodegenerative disease Friedreich ataxia (FRDA). Here, we show that normal upregulation of the stress defense protein manganese superoxide dismutase (MnSOD) fails to occur in FRDA fibroblasts exposed to iron. This impaired induction was observed at iron levels in which increased activation of the redox-sensitive factor NF-kappaB was absent. Furthermore, MnSOD induction could only be partially suppressed by antioxidants. We conclude that an NF-kappaB-independent pathway that may not require free radical signaling is responsible for the reduction of MnSOD induction. This impairment could constitute both a novel defense mechanism against iron-mediated oxidative stress in cells with mitochondrial iron overload and conversely, an alternative source of free radicals that could contribute to the disease pathology.

Analysis of the enzymatic domains in the modular portion of the coronafacic acid polyketide synthase

Coronafacic acid (CFA) is the polyketide component of coronatine (COR), a phytotoxin produced by the plant pathogen Pseudomonas syringae. The CFA polyketide synthase (PKS) consists of two open reading frames (ORFs) that encode type I multifunctional proteins and several ORFs that encode monofunctional proteins. Sequence comparisons of the modular portions of the CFA PKS with other prokaryotic, modular PKSs elucidated the boundaries of the domains that are involved in the individual stages of polyketide assembly. The two beta-ketoacyl:acyl carrier protein synthase (KS) domains in the modular portion of the CFA PKS exhibit a high degree of similarity to each other (53%), but are even more similar to the KS domains of DEBS, RAPS, and RIF. Cfa6 possesses two acyltransferases- AT0, which is associated with a loading domain, and AT1, which uses ethylmalonyl-CoA (eMCoA) as a substrate for chain extension. Cfa7 contains an AT that uses malonyl-CoA as a substrate for chain extension. The Cfa6 AT0 shows 35 and 32% similarity to the DEBS1 and NidA1 AT0s, respectively, and 32 and 36% similarity to the Cfa6 and Cfa7 AT1s. Sequence motifs have previously been identified that correlate with AT substrates. The motifs in Cfa6 AT1 were found to correlate reasonably well with those predicted for methylmalonyl-CoA (mMCoA) ATs. The motifs in the AT of Cfa7 correlated more poorly with those predicted for MCoA ATs. Three ACP domains occur in the modular proteins of the COR PKS. The loading domain-associated ACP0 showed 38% similarity to the loading domain ACP0s of DEBS1 and NidA1 and 32-36% similarity to the two module-associated ACPs of the COR PKS. It exhibited a higher degree of similarity to the module-associated ACPs of RAPS. The two module-associated ACPs show 39% similarity to each other, but appear more closely related to module-associated ACP domains in RAPS and RIFS. Furthermore, the DH and KR domains of Cfa6 and Cfa7 show greater similarity to DH and KR domains in RAPS and RIFS than to each other. The CFA PKS includes a thioesterase domain (TE I) that resides at the C-terminus of Cfa7 and a second thioesterase, which exists as a separate ORF (Cfa9, a TE II). Analysis of a Cfa7 thioesterase mutant demonstrated that the TE domain is required for the production of CFA. The co-existence of TE domains within modular PKSs along with physically separated, monofunctional TEs (TE IIs) has been reported for a number of modular polyketide and non-ribosomal peptide synthases (NRPS). An analysis of the two types of thioesterases using Clustal X yielded a dendrogram showing that TE IIs from PKSs and NRPSs are more closely related to each other than to domain TEs from either PKSs or NRPSs. Furthermore, the dendrogram indicates that both types of TE IIs are more closely related to TE domains associated with PKSs than to TE domains in NRPSs. Finally, the overall % G+C content and the % G+C content at the third codon for all of the PKS genes in the COR cluster suggest that these genes may have been recruited from a gram-positive bacterium.

Knock-out of the cyaY gene in Escherichia coli does not affect cellular iron content and sensitivity to oxidants

Friedreich ataxia is a recessively inherited neurodegenerative disease caused by deficiency of a highly conserved mitochondrial protein, frataxin. Frataxin deficiency results in mitochondrial iron accumulation and oxidative stress. Frataxin shows homology with the CyaY proteins of gamma-purple bacteria, whose function is unknown. We knocked out the CyaY gene in Escherichia coli MM383 by homologous recombination and we generated an E. coli MM383 strain overexpressing CyaY. Bacterial growth, iron content and survival after exposure to H2O2 did not differ among these strains, suggesting that, despite structural similarities, cyaY proteins in bacteria may have a different function from frataxin homologues in mitochondria.

Biosynthesis of the Pseudomonas polyketide coronafacic acid requires monofunctional and multifunctional polyketide synthase proteins

Coronafacic acid (CFA) is the polyketide component of the phytotoxin coronatine, a virulence factor of the plant pathogen Pseudomonas syringae. Our current knowledge of polyketide biosynthesis largely is based on the analysis of polyketide synthases (PKSs) in actinomycetes and other Gram-positive bacteria. Consequently, the cloning and characterization of the CFA biosynthetic gene cluster will contribute significantly to our knowledge of polyketide synthesis in Pseudomonas. In this report, we describe two genes in the CFA biosynthetic gene cluster that encode PKSs that are structurally and functionally similar to the multifunctional modular PKSs, which catalyze the synthesis of macrolide antibiotics. The CFA PKS genes were overproduced in Escherichia coli and shown to cross-react with antisera made to a modular PKS involved in erythromycin synthesis. A scheme for CFA biosynthesis is presented that incorporates the activities of all proteins in the CFA PKS. In this report a gene cluster encoding a pseudomonad polyketide has been completely sequenced and the deduced gene functions have been used to develop a biosynthetic scheme.

Frataxin is reduced in Friedreich ataxia patients and is associated with mitochondrial membranes

Friedreich ataxia is a progressive neurodegenerative disorder caused by loss of function mutations in the frataxin gene. In order to unravel frataxin function we developed monoclonal antibodies raised against different regions of the protein. These antibodies detect a processed 18 kDa protein in various human and mouse tissues and cell lines that is severely reduced in Friedreich ataxia patients. By immunocytofluorescence and immunocytoelectron microscopy we show that frataxin is located in mitochondria, associated with the mitochondrial membranes and crests. Analysis of cellular localization of various truncated forms of frataxin expressed in cultured cells and evidence of removal of an N-terminal epitope during protein maturation demonstrated that the mitochondrial targetting sequence is encoded by the first 20 amino acids. Given the shared clinical features between Friedreich ataxia, vitamin E deficiency and some mitochondriopathies, our data suggest that a reduction in frataxin results in oxidative damage.

Somatic mosaicism for Friedreich's ataxia GAA triplet repeat expansions in the central nervous system

Most patients with Friedreich's ataxia (FRDA) carry expanded GAA repeats in both homologues of the frataxin gene on chromosome 9. We determined the size of the GAA repeats in autopsied samples from the CNS of six FRDA patients. We observed heterogeneity of repeat sizes in different CNS regions, indicative of extensive mitotic instability. Samples from the same CNS subdivision (e.g., cortex, thalamus) contained a similar mixture of alleles, suggesting that the pattern of repeat size mosaicism reflects the developmental history of each sample. Regional differences in repeat size could not account for the characteristic distribution of pathology in FRDA, which appears instead to be related to the pattern of frataxin expression.

Regulation of mitochondrial iron accumulation by Yfh1p, a putative homolog of frataxin

The gene responsible for Friedreich's ataxia, a disease characterized by neurodegeneration and cardiomyopathy, has recently been cloned and its product designated frataxin. A gene in Saccharomyces cerevisiae was characterized whose predicted protein product has high sequence similarity to the human frataxin protein. The yeast gene (yeast frataxin homolog, YFH1) encodes a mitochondrial protein involved in iron homeostasis and respiratory function. Human frataxin also was shown to be a mitochondrial protein. Characterizing the mechanism by which YFH1 regulates iron homeostasis in yeast may help to define the pathologic process leading to cell damage in Friedreich's ataxia.

Frataxin shows developmentally regulated tissue-specific expression in the mouse embryo

Friedreich ataxia (FRDA) is an autosomal recessive degenerative disease caused either by an intronic GAA triplet repeat expansion that suppresses the expression of the frataxin gene on chromosome 9q13, or, rarely, by point mutations in the frataxin gene. We investigated the expression of the mouse frataxin homologue during embryonic development by Northern blot analysis and RNA in situ hybridization. Very faint expression could be detected from E10.5 in the neuroepithelium and more clearly from E12.5 in the developing central nervous system. At E14.5, frataxin was expressed at a much higher level that remained constant into the postnatal period. Maximum expression was observed in the spinal cord, particularly at the thoracolumbar level, and in the dorsal root ganglia. Significant levels of transcript could also be detected in the proliferating cells in the periventricular zone, in the cortical plates, in the heart, in the axial skeleton, and in some epithelial and mesenchymal tissues. Overall, the distribution of frataxin mRNA was in good accordance with previous data from Northern analysis of adult human tissues, the major discrepancy being the expression in mouse embryonic cerebral cortex which was not observed in adult human brain. The tissues expressing frataxin during development appear to be those that become dysfunctional or atrophied in FRDA. Overall, our data suggest that frataxin is a protein whose expression is cell-specific and developmentally regulated.

Regulation of the hypoxanthine phosphoribosyltransferase gene: in vitro and in vivo approaches

The hypoxanthine phosphoribosyltransferase (HPRT) locus is a constitutively expressed housekeeping gene characterized by a notably higher level of expression in the mammalian brain. The enzyme it encodes is key to purine salvage in humans and is the basis for the X-linked recessive disorder, Lesch-Nyhan syndrome (LNS). Methylation in the promoter plays a critical, if not fully understood, role in transcriptional silencing of the locus on the inactive chromosome, possibly by conferring structural stability. In vivo footprinting assays of the promoter region have shown protein interaction with multiple Spl-binding sites, a possible AP2 site, and a potentially novel binding site. In vitro studies of HPRT promoter deletion constructs have identified a minimal promoter element necessary for maximal transcription and a position-dependent, orientation-independent repressor element (HPRT-NE) that functions on heterologous promoters. Regulatory intron elements have also been observed. Studies on transgenic mice bearing HPRT promoter constructs have shown that the minimal promoter element is insufficient for in vivo expression and that HPRT-NE is responsible for conferring neuronal specificity. HPRT-mice possess metabolic defects similar to LNS patients, but fail to develop human behavioral abnormalities, perhaps because of species differences in purine metabolism. A neuronal-specific protein complex appears to be necessary for activator function of HPRT-NE, while a ubiquitously expressed complex may be responsible for repression. Sequence analysis Indicates that the latter complex may depend on the multifunctional transcription factor YY1 for binding. A fuller understanding of HPRT gene regulation will hopefully provide insight into the transcriptional mechanisms controlling the expression of housekeeping and brain-specific genes.

Haploinsufficiency of cytosolic serine hydroxymethyltransferase in the Smith-Magenis syndrome

Folate-dependent one-carbon metabolism is critical for the synthesis of numerous cellular constituents required for cell growth, and serine hydroxymethyltransferase (SHMT) is central to this process. Our studies reveal that the gene for cytosolic SHMT (cSHMT) maps to the critical interval for Smith-Magenis syndrome (SMS) on chromosome 17p11.2. The basic organization of the cSHMT locus on chromosome 17 was determined and was found to be deleted in all 26 SMS patients examined by PCR, FISH, and/or Southern analysis. Furthermore, with respect to haploinsufficiency, cSHMT enzyme activity in patient lymphoblasts was determined to be approximately 50% that of unaffected parent lymphoblasts. Serine, glycine, and folate levels were also assessed in three SMS patients and were found to be within normal ranges. The possible effects of cSHMT hemizygosity on the SMS phenotype are discussed.

The gene for a human microfibril-associated glycoprotein is commonly deleted in Smith-Magenis syndrome patients

Smith-Magenis syndrome (SMS) is a clinically recognizable multiple congenital anomaly/mental retardation syndrome associated with deletion of chromosome 17p11.2. Here we report the identification of a novel gene encoding a human microfibril-associated glycoprotein (MFAP4), which has been mapped to the SMS region. A full-length cDNA corresponding to this gene has been sequenced, and reveals a coding region of 255 amino acids. MFAP4 has a fibrinogen-like domain and shares a high level of sequence homology to a fragment of a bovine 36 kDa microfibril-associated glycoprotein. The N-terminus of the protein bears an Arg-Gly-Asp sequence that serves as the ligand motif for cell surface receptor integrin. These structural features of MFAP4 suggest that it is an extracellular matrix protein involved in cell adhesion or intercellular interactions. Deletion analysis has been conducted on 31 SMS patients by polymerase chain reaction and Southern analysis of somatic cell hybrids retaining the del(17)(p11.2) chromosome or by fluorescence in situ hybridization. The MFAP4 locus is deleted in 30 of 31 SMS patients. Thus, the function of this gene must be considered in the pathogenesis of SMS. Given our previous hypothesis that SMS is a contiguous gene syndrome, complete and exhaustive definition of the critical deletion interval and a thorough phenotype-genotype correlation is required to demonstrate the role and importance of the MFAP4 gene in SMS.