Impact of baseline BMI and weight change in CCTG adjuvant breast cancer trials

Background

We hypothesized that increased baseline BMI and BMI change would negatively impact clinical outcomes with adjuvant breast cancer systemic therapy.

Methods

Data from chemotherapy trials MA.5 and MA.21; endocrine therapy MA.12, MA.14 and MA.27; and trastuzumab HERA/MA.24 were analyzed. The primary objective was to examine the effect of BMI change on breast cancer-free interval (BCFI) landmarked at 5 years; secondary objectives included BMI changes at 1 and 3 years; BMI changes on disease-specific survival (DSS) and overall survival (OS); and effects of baseline BMI. Stratified analyses included trial therapy and composite trial stratification factors.

Results

In pre-/peri-/early post-menopausal chemotherapy trials (N = 2793), baseline BMI did not impact any endpoint and increased BMI from baseline did not significantly affect BCFI (P = 0.85) after 5 years although it was associated with worse BCFI (P = 0.03) and DSS (P = 0.07) after 1 year. BMI increase by 3 and 5 years was associated with better DSS (P = 0.01; 0.01) and OS (P = 0.003; 0.05). In pre-menopausal endocrine therapy trial MA.12 (N = 672), patients with higher baseline BMI had worse BCFI (P = 0.02) after 1 year, worse DSS (P = 0.05; 0.004) after 1 and 5 years and worse OS (P = 0.01) after 5 years. Increased BMI did not impact BCFI (P = 0.90) after 5 years, although it was associated with worse BCFI (P = 0.01) after 1 year. In post-menopausal endocrine therapy trials MA.14 and MA.27 (N = 8236), baseline BMI did not significantly impact outcome for any endpoint. BMI change did not impact BCFI or DSS after 1 or 3 years, although a mean increased BMI of 0.3 was associated with better OS (P = 0.02) after 1 year. With the administration of trastuzumab (N = 1395) baseline BMI and BMI change did not significantly impact outcomes.

Conclusions

Higher baseline BMI and BMI increases negatively affected outcomes only in pre-/peri-/early post-menopausal trial patients. Otherwise, BMI increases similar to those expected in healthy women either did not impact outcome or were associated with better outcomes.

Clinical Trials numbers

CAN-NCIC-MA5; National Cancer Institute (NCI)-V90-0027; MA.12-NCT00002542; MA.14-NCT00002864; MA.21-NCT00014222; HERA, NCT00045032;CAN-NCIC-MA24; MA-27-NCT00066573.

Abstract P1-07-13: Prognostic relevance of statistically standardized estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) in tamoxifen(TAM)-treated NCIC CTG MA.14 patients

Background: Poor inter-laboratory comparability of common clinically used breast cancer biomarkers led to a proposal of statistical standardization (SS) of laboratory results, similar to bone mineral density (BMD) z-scores. This analysis is the first utilization of SS in a trial where all women received TAM.

Methods: MA.14 allocated 667 postmenopausal women to TAM +/− Octreotide LAR (OCT) based on locally determined ER/PR, without HER2 status. At 9.8 yrs median follow-up, the secondary endpoint of relapse-free survival (RFS) had a non-significant hazard ratio (HR) for TAM-OCT to TAM of 0.87 (95% CI 0.63–1.21; p = 0.40). 299 patients who were representative of MA.14 patients by treatment and stratification factors (exact Fisher p-values=0.19–0.90) had their tumors centrally assessed for ER, PR, and HER2 by RT-PCR. Continuous values were used for SS of each biomarker. Univariate (uni) assessment used similar categorizations as those for BMD, assigning ER/PR/HER2 values by number of standard deviations (SD) about the mean (Group 1, z-score ≥1.0 SD below mean; Group 2, z-score <1.0 SD below mean; Group 3, z-score ≤1.0 SD above mean; Group 4, z-score >1.0 SD above mean). A log-rank statistic was used to test for differences between SS biomarker groups with K-M plots for graphical description. Multivariate (multi) effects of SS biomarkers and baseline patient characteristics on RFS were examined with exploratory (un)stratified Cox step-wise forward regression, adding a factor if likelihood ratio criterion was p ≤ 0.05. Sensitivity analyses used a prior external HER2+ cut-point of ≥1.32 SD.

Results: 292 patient samples passing internal analytical quality control were included in this analysis. Uni analyses indicated SS ER was not associated with RFS (p = 0.31). SS PR had a significant uni effect on RFS [p = 0.03; Group 4 compared to Group 1, HR of 0.33 (95% CI 0.12–0.90); Group 3 compared to Group 1, HR of 0.42 (95% CI 0.21–0.83); and Group 2 compared to Group 1 HR of 0.70 (95%CI 0.36–1.37)]. SS HER2 also had a significant uni effect on RFS [p = 0.004; Group 4 compared to Group 1, HR of 0.90 (95% CI 0.37–2.16)]; Group 3 compared to Group 1, HR of 0.39 (95% CI 0.18–0.84); and, Group 2 compared to Group 1, HR of 0.34 (95% CI 0.16–0.70)]. Multi stratified/unstratified Cox models indicated T1 tumours (p = 0.02/p = 0.0002) and higher SS PR (p = 0.02/0.01) were associated with significantly longer RFS; other unstratified results showed that N-ve patients had better RFS (p < .0001), while local ER/PR status did not impact RFS (p > 0.05). The HER2+ cut-point of ≥1.32 SD indicated directionally worse RFS (uni p-value=0.05; multi p-value=0.06).

Discussion: In MA.14, all women received TAM. Local ER/PR status using categorical or semi-quantitative values did not impact RFS. A statistically standardized approach using continuous centralized ER, PR, HER2 by RT-PCR demonstrated that increasing PR values were associated with better RFS. Evaluation in other trials may provide support for this methodology.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-07-13.

Glycemic load effect on fasting and post-prandial serum glucose, insulin, IGF-1 and IGFBP-3 in a randomized, controlled feeding study

BACKGROUND/OBJECTIVES

The effect of a low glycemic load (GL) diet on insulin-like growth factor-1 (IGF-1) concentration is still unknown but may contribute to lower chronic disease risk. We aimed to assess the impact of GL on concentrations of IGF-1 and IGF-binding protein-3 (IGFBP-3).

SUBJECTS/METHODS

We conducted a randomized, controlled crossover feeding trial in 84 overweight obese and normal weight healthy individuals using two 28-day weight-maintaining high- and low-GL diets. Measures were fasting and post-prandial concentrations of insulin, glucose, IGF-1 and IGFBP-3. In all 80 participants completed the study and 20 participants completed post-prandial testing by consuming a test breakfast at the end of each feeding period. We used paired t-tests for diet component and linear mixed models for biomarker analyses.

RESULTS

The 28-day low-GL diet led to 4% lower fasting concentrations of IGF-1 (10.6 ng/ml, P=0.04) and a 4% lower ratio of IGF-1/IGFBP-3 (0.24, P=0.01) compared with the high-GL diet. The low-GL test breakfast led to 43% and 27% lower mean post-prandial glucose and insulin responses, respectively; mean incremental areas under the curve for glucose and insulin, respectively, were 64.3±21.8 (mmol/l/240 min; P<0.01) and 2253±539 (μU/ml/240 min; P<0.01) lower following the low- compared with the high-GL test meal. There was no effect of GL on mean homeostasis model assessment for insulin resistance or on mean integrated post-prandial concentrations of glucose-adjusted insulin, IGF-1 or IGFBP-3. We did not observe modification of the dietary effect by adiposity.

CONCLUSIONS

Low-GL diets resulted in 43% and 27% lower post-prandial responses of glucose and insulin, respectively, and modestly lower fasting IGF-1 concentrations. Further intervention studies are needed to weigh the impact of dietary GL on risk for chronic disease.

P5-14-01: Differences in Efficacy by Assessment Method: NCIC CTG Adjuvant Breast Cancer Trials MA.5, MA.12, MA.14, MA.21, MA.27 Meta-Analysis

Background: Based on recent breast cancer literature, we hypothesized that there could be substantive differences in apparent efficacy estimates using a log-normal (LN) survival model rather than with standard Kaplan-Meier (K-M) or Cox model methods. While both Cox and LN survival analyses offer greater specification by individual patient characteristics, the LN model may more robustly estimate survival under model misspecification. Methods: We recently pooled data for 5 NCIC CTG primary breast cancer trials: MA.5, MA.12, MA.14, MA.21, and MA.27. The total patient count for patients who received at least 1 dose of trial therapy is 11,253. Compilation included definition of STEEP endpoints (C Hudis, JCO, 2008) and standardized factor categorizations. The primary endpoint is Breast Cancer Free Interval (BCFI) defined as the time from randomization until recurrence: first local invasive or DCIS; regional, or distant; contralateral invasive or DCIS; or death from breast cancer. We found substantive evidence of non-proportionality for 7 factors compiled for the meta-analyses. In this work, we fit multivariate Cox and LN models with these 7 factors, lymph node status and pathologic T status. We then compare BCFI efficacy estimates for patient and tumour characteristics at 1-, 3-, and 5-years obtained with K-M, Cox, and LN models. Results: There was evidence that the Cox assumption of proportional hazards was violated for 7 factors: age, menopausal status, hormone receptor status, anthracycline use, chemotherapy use, race, and ECOG performance status. Differences between models were intrinsically affected by timing and extent of non-proportionality; there was no consistent pattern. In particular, investigations to date indicate efficacy estimates with absolute differences between K-M, Cox and LN estimates which varied by time of assessment: at 1-year 0.0 to 6.7%, at 3-years 0.4 to 18.6%, and at 5-years 0.2 to 17.0%. BCFI estimates with the K-M were inconsistently closer to those with the LN or Cox model: for K-M to Cox at 1-year 0.4 to 5.2%, at 3-years 0.4 to 15%, at 5-years 0.4 to 14.3%; for K-M to LN at 1-year 0.0 to 6.7%, at 3-years 0.5 to 18.6%, at 5-years 0.2 to 17.0%; for Cox to LN at 1-year 0.8 to 1.8%, at 3-years 1.9 to 6.0%, at 5-years 0.6 to 5.7%. K-M and Cox models have step-wise adjustments at events for K-M and Cox, rather than smooth modeling with the LN. Discussion: Even with reasonably large population subgroups, there were substantive differences in apparent survival (0.0 to 18.6%) between K-M, Cox and LN model types. The magnitude of differences in survival estimates was large enough to be clinically relevant and warrant further consideration as we evaluate new therapies and prognostic/predictive factors. We will be statistically investigating framework robustness under differing levels of model misspecification.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-14-01.

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.

Utilizing metformin to enhance the efficacy of androgen-deprivation therapy in the treatment of prostate cancer

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Background: Prostate cancer (PCa) incidence varies by geographic location, with developed countries exhibiting higher levels of disease. Some attribute this to the “Westernized lifestyle” of high energy diets and limited physical activity with consequent obesity. Obesity and related diseases like diabetes, cause hyperinsulinemia, which upregulates pro-survival insulin/insulin-like growth factor signalling. Previous work shows diet-induced hyperinsulinemia enhances PCa tumor growth in vivo. Metformin, a diabetic treatment, reduces hyperinsulinemia, and also exhibits anti-neoplastic properties. We assessed the potential benefit of combining a standard PCa treatment (bicalutamide) with metformin in vitro and in vivo.

Methods: The effect of bicalutamide and/or metformin on colony formation rates was assessed in LNCaP, PC3, DU145 and PC3AR2 PCa cell lines using clonogenic assay. Western blot and cell cycle analyses were used to elucidate mechanisms of interaction between the drugs. The combination treatment regimen was assessed in vivo using a murine xenograft model.

Results: Micromolar bicalutamide or millimolar metformin caused significant dose-dependent reduction in colony formation rates (p<0.001). Combination treatment further significantly reduced colony formation rates (p<0.005). Differing mechanisms of interaction occurred in AR positive and negative cell lines. Following combination treatment LNCaP cells exhibited altered cell proliferation (decreased PCNA) and perturbed cell cycle kinetics (G1/S arrest). PC3 cells showed evidence of enhanced apoptosis (increased BAX, decreased caspase 3, phospho-Akt). Preliminary in vivo results show significantly diminished tumor growth following combination treatment (p<0.0001).

Conclusions: Combining bicalutamide and metformin significantly reduces PCa cell colony formation rates further than either monotherapy. In AR positive cells this effect is mediated by reducing cell proliferation rates, whereas in AR negative cells combination treatment promotes apoptosis. This combination drug regimen may potentially improve prostate-cancer specific survival via the direct anti-neoplastic properties outlined.

[Table: see text]

Utilizing metformin as a radiosensitizing agent in the treatment of prostate cancer

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Background: External beam radiation therapy (EBRT) is a well recognized curative prostate cancer (PCa) treatment modality utilizing ionizing radiation (IR). In addition to mediating DNA damage, IR upregulates several intracellular pro-survival pathways including the insulin- like growth factor (IGR) signaling network. This may contribute to the intrinsic radioresistance exhibited by certain tumors. Diabetic patients with PCa experience poorer outcomes following EBRT than their non-diabetic counterparts. Some attribute this to diabetes-induced chronic hyperinsulinemia with consequent upregulation of pro-survival insulin/IGF signalling. Previous work by our group showed diet-induced hyperinsulinemia to enhance PCa tumor growth in vivo. Metformin, a diabetic treatment, alleviates hyperinsulinemia, and also exhibits anti-neoplastic properties. We postulate that pre-treatment with metformin to correct hyperinsulinemia may protect cells from radiation-mediated pro-survival insulin/IGF signaling. Thus we assessed the radiosensitizing potential of metformin using in vitro and in vivo PCa models.

Methods: The effect of IR and/or metformin on colony formation rates was assessed in LNCaP, PC3, DU145 and PC3AR2 PCa cell lines using clonogenic assay. The combination treatment regimen was assessed in vivo using a murine xenograft model. Western blot and cell cycle analyses are ongoing to try and elucidate any mechanisms of interaction between metformin and IR.

Results: Monotherapy with IR (1-8Gy) or metformin (0.01-10.0mM) caused significant dose-dependent reduction in colony formation rates (p<0.001). Combination treatment further significantly reduced colony formation rates (p<0.03). Preliminary results from our in vivo study show diminished tumor growth in response to combination treatment (p<0.0001), and are currently subject to ongoing statistical analyses.

Conclusions: Our in vitro findings confirm combining metformin with IR significantly reduces PCa cell colony formation rates further than either monotherapy. Recapitulation of these results in vivo would provide justification for translating this work into a phase II clinical trial of metformin as a radiosensitizing agent.

No significant financial relationships to disclose.

Pre-treatment levels of circulating free IGF-1 identify NSCLC patients who derive clinical benefit from figitumumab

BACKGROUND

Phase III trials of the anti-insulin-like growth factor type 1 receptor (IGF-IR) antibody figitumumab (F) in unselected non-small-cell lung cancer (NSCLC) patients were recently discontinued owing to futility. Here, we investigated a role of free IGF-1 (fIGF-1) as a potential predictive biomarker of clinical benefit from F treatment.

MATERIALS AND METHOD

Pre-treatment circulating levels of fIGF-1 were tested in 110 advanced NSCLC patients enrolled in a phase II study of paclitaxel and carboplatin given alone (PC) or in combination with F at doses of 10 or 20 mg kg(-1) (PCF10, PCF20).

RESULTS

Cox proportional hazards model interactions were between 2.5 and 3.5 for fIGF-1 criteria in the 0.5-0.9 ng ml(-1) range. Patients above each criterion had a substantial improvement in progression-free survival on PCF20 related to PC alone. Free IGF-1 correlated inversely with IGF binding protein 1 (IGFBP-1, ρ=-0.295, P=0.005), and the pre-treatment ratio of insulin to IGFBP-1 was also predictive of F clinical benefit. In addition, fIGF-1 levels correlated with tumour vimentin expression (ρ=0.594, P=0.021) and inversely with E-cadherin (ρ=-0.389, P=0.152), suggesting a role for fIGF-1 in tumour de-differentiation.

CONCLUSION

Free IGF-1 may contribute to the identification of a subset of NSCLC patients who benefit from F therapy.

Abstract P4-09-09: Serum SDF-1: Biomarker of Bone Relapse in the NCIC MA.14 Adjuvant Breast Cancer Trial

Background: Massague et al have shown that breast cancer cell line subpopulations with elevated bone metastatic activity overexpress chemokine receptor 4 (CXCR4), interleukin 11 (IL11), osteopontin (OPN) and connective tissue growth factor (CTGF) (Cancer Cell 3:537, 2003). CXCR4 overexpression results in bone-homing and extravasation of tumor cells in bone. In MA.14, we found that serum β-CTx was associated with bone-only relapse while Basik et.al showed that higher serum stromal cell-derived factor 1 (SDF-1) (ligand for CXCR-4) levels were associated with worse overall event-free survival (EFS) (ASCO 2010). In this study, we examined concurrently the association of both β-CTx and serum SDF-1 with bone relapse.

Methods: Serum β-CTx (Serum CrossLaps, Nordic Biosciences, Copenhagen, DN) was determined in pretreatment sera from 621 of 667 NCIC CTG MA.14 patients. SDF-1 (CXCL12) (R&D Systems, Minneapolis, MN) levels were successfully determined in the 4 month post-treatment serum (SDF-1) for 508 (76%) of the patients. Trial stratification was by administration of adjuvant chemotherapy, axillary lymph node status, and ER and/or PR status. Recurrence-free survival (RFS) was defined as the time from randomization to the time of recurrence of the primary disease. Adjusted and unadjusted Cox step-wise forward multivariate analyses were used to assess the effects of β-CTx, SDF-1, trial therapy and baseline patient characteristics on non-bone, all bone and bone-only RFS; a factor was added if p&lt;=0.05.

Results: Joint assessment of β-CTx and SDF-1 was possible for 493 (74%) of the 667 patients. Imbalances in who was, or was not, included in this subset led to the trial arm of Tamoxifen + Octreotide LAR having a significant longer unadjusted ITT non-bone RFS (p=0.03-0.06). There was shorter time to bone metastasis of any type with higher lymph node involvement (p=0.001), larger T (p=0.02), and higher log SDF-1 (p=0.03). Meanwhile, high categorical and continuous β-CTx was associated multivariately with shorter bone-only RFS (p=0.04 and 0.01, respectively); higher log SDF-1 was only associated with shorter bone-only RFS (p=0.02) when the number of strata were reduced to 2 categories per factor.

Conclusions: Higher serum SDF-1 level may be associated with bone metastasis, although there is less evidence of its relevance in bone-only relapse than there is for the biomarker β-CTx. Serum SDF-1 deserves further study as a promising predictive factor of bone relapse in breast cancer.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-09-09.

Serum 1-OH vitamin D (D) and prognosis of postmenopausal breast cancer (BC) patients: NCIC-CTG MA14 trial

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Background: In vitro, D has demonstrated regulatory functions in breast cancer cells and the bone microenvironment. Higher serum D levels were associated in some prior studies with favorable BC prognosis. We previously found that the baseline serum bone resorption marker, beta C-terminal telopeptides of type I collagen (B-CTx), was associated with bone-only first relapse, and that higher levels of insulin secretion as estimated by c-peptide level was associated with reduced event-free survival (EFS). We hypothesized that baseline serum D might be associated with relapse of breast cancer in bone and/or other metastatic sites. Methods: Baseline D was determined for the phase III MA.14 trial of adjuvant tamoxifen (20 mg/day oral for 5 years) ± octreotide (90 mg/month depot injection for 2 years). Stratification was by adjuvant chemotherapy, axillary lymph node status, and hormone receptor status. EFS, time from randomization to recurrence, second malignancy, or death due to any cause, was the primary endpoint. Recurrence-free survival (RFS), time from randomization to recurrence of the primary disease alone, was a secondary endpoint. For both endpoints, step-wise forward multivariate Cox regression adjusted for stratification factors was used to examine the association of D and outcome; a factor was added if p < 0.05. Results: Baseline D levels were available for 607 (91%) patients. As expected, D levels for a population far from the equator varied with month of blood draw (p = 0.007), which gives confidence in assay performance. Continuous D was not associated with RFS of any relapse (p = 0.57), bone only relapse (p = 0.19), bone + other site of relapse (p = 0.73), or all bone relapse types (p = 0.66). D was not associated with EFS (0.43), even when adjusted by season (p = 0.64), level deficiency/insufficiency vs sufficiency/toxicity (p = 0.69), age (p = 0.54), and BMI (p = 0.32). As well, interactions between D and season, age, and BMI were non-significant (respectively, p = 0.90, 0.84, 0.23). Conclusions: D was not associated with EFS or RFS in postmenopausal breast cancer patients in this well controlled hormonal therapy study, a result consistent with some, but not all, studies of this issue.

No significant financial relationships to disclose.

Dependence of malignant proliferation associated with loss of PTEN on glucose concentration in the hyperglycemic range: Relevance to population studies linking hyperglycemia to unfavorable cancer prognosis

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Background: Loss of function of the tumor suppressor PTEN enhances malignant proliferation, but effects on cellular energy metabolism are less well characterized. Population studies show that the metabolic syndrome (characterized by hyperglycemia, hyperinsulinism, and obesity) is increasingly prevalent in affluent societies and is associated with adverse outcome of many cancers, but the molecular basis for this is poorly understood. Methods: We used a tetracycline-inducible PTEN expression vector in the PTEN-null U251 glioma cell line to characterize effects of PTEN on cellular energy metabolism. Results: Forced expression of PTEN led to decreased phospho-AKTSer473, decreased hexokinase II and HIF-1 alpha levels, and increased p53 levels. While proliferation of PTEN-positive cells was insensitive to variation in glucose concentration at levels higher than 2.5 mM, PTEN-null cells significantly increased proliferation with increasing glucose concentration across normal physiologic range to ∼10 mM. PTEN-null cells consumed more glucose than PTEN-positive cells (17.2 ± 2.0 vs. 8.8 ± 1.5 mM/million cells/48 hrs) and produced more lactate (35.9 ± 4.8 vs. 10.7 ± 2.3 mM/million cells/48 hrs). When cells were incubated in presence of 2-deoxy-glucose (2-DG), growth inhibition was greater for PTEN-null cells (47.4% inhibition relative to control without 2-DG) compared with PTEN-positive cells (10.8% inhibition relative to control without 2-DG). Conclusions: Loss of function of PTEN leads to increased glycolysis, and increased dependence on glucose availability. Only in the presence of glucose in the hyperglycemic range are maximal adverse effects of loss of PTEN on cellular proliferation and survival seen. This provides a novel mechanism to explain at least in part the relationship between hyperglycemia and cancer mortality observed in several large population studies. The data also suggest that PTEN status is relevant to selection of tumors likely to respond to experimental therapies that exploit glucose dependency.

No significant financial relationships to disclose.

Pharmacodynamic properties of the anti-IGF-IR monoclonal antibody CP-751,871 in cancer patients

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Background: The Insulin like Growth Factor I receptor (IGF-IR), a tyrosine kinase, is widely expressed in human tissues. IGF- IR and its ligands (IGF-I and IGF-II) are expressed by many human cancers (e.g., breast, prostate, colorectal and non-small cell lung). Binding of the ligands to the IGF-IR activates key cellular signaling pathways important for stimulating cellular proliferation and inhibiting apoptosis. IGF- I and IGF-II are present in the circulation, but also locally expressed in neoplastic tissue. Bioavailability of these ligands is regulated by a family of IGF binding proteins (IGFBPs1–6). CP-751,871, a fully human monoclonal antibody, is a highly specific and potent inhibitor of IGF-IR activation. In vitro experiments show that binding of CP 751,871 to IGF-IR induces receptor internalization and degradation. This antibody has been shown to have antineoplastic activity using both in vivo and in vitro pre-clinical models. Methods: Blood samples were collected for characterization of the pharmacokinetic and pharmacodynamic properties of CP-751,871 in phase 1 trials of this agent given to cancer patients either alone or in combination with chemotherapy. The endpoints assessed included among others: CP-751,871 plasma concentrations, total and free IGF-I, IGFBP-3, soluble IGF-IR and IGF-IR expression on granulocytes and tumor cells. Results: CP 751,871 exposure increased with dose over the 800-fold dose range investigated. Pharmacokinetic profiles were consistent with target-mediated disposition. A dose-dependent downregulation of soluble IGF-IR serum concentration and IGF-IR expression was observed, with sustained inhibition for the entire dosing period (3–4 week cycles) observed at doses ≥ 1.5 mg/kg. As predicted for an agent that interferes with IGF-I action, IGF-I and IGFBP-3 serum levels were up-regulated in a similar dose-dependent manner. Conclusions: The pharmacodynamic endpoints of clinical trials provide evidence that CP-751,871 targets IGF-IR in granulocytes, tumor cells and tissues involved in regulation of the growth hormone -IGF-I axis. These data provide proof of principle for the use of CP-751,871 as a first-in-class therapeutic approach to inhibit the IGF-IR pathway in cancer patients.

No significant financial relationships to disclose.

Circulating insulin-like growth factor axis and the risk of pancreatic cancer in four prospective cohorts

Insulin-like growth factor (IGF)-I induces growth in pancreatic cancer cells and blockade of the IGF-I receptor has antitumour activity. The association of plasma IGF-I and IGF binding protein-3 (IGFBP-3) with pancreatic cancer risk has been investigated in two small studies, with conflicting results. We conducted a nested case–control study within four large, prospective cohorts to investigate whether prediagnostic plasma levels of IGF-I, IGF-II, and IGFBP-3 were associated with pancreatic cancer risk. Plasma levels in 212 cases and 635 matched controls were compared by conditional logistic regression, with adjustment for other known pancreatic cancer risk factors. No association was observed between plasma levels of IGF-I, IGF-II, or IGFBP-3 and incident diagnosis of pancreatic cancer. Relative risks for the highest vs the lowest quartile of IGF-I, IGF-II, and IGFBP-3 were 0.94 (95% confidence interval (CI), 0.60–1.48), 0.96 (95% CI, 0.61–1.52), and 1.21 (95% CI, 0.75–1.92), respectively. The relative risk for the molar ratio of IGF-I and IGFBP-3, a surrogate measure for free IGF-I, was 0.84 (95% CI, 0.54–1.31). Additionally, no association was noted in stratified analyses or when requiring longer follow-up. In four prospective cohorts, we found no association between the risk of pancreatic cancer and prediagnostic plasma levels of IGF-I, IGF-II, or IGFBP-3.

Insulin resistance, estimated by serum C-peptide level, is associated with reduced event-free survival for postmenopausal women in NCIC CTG MA.14 adjuvant breast cancer trial

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Background: NCIC CTG MA.14 is a randomized multi-centre trial of tamoxifen versus combined tamoxifen and octreotide LAR therapy in the adjuvant treatment of breast cancer in post-menopausal women. Planned secondary analyses included investigation of baseline metabolic factors that might influence survival. Laboratory and clinical studies indicate that insulin resistance is associated with adverse outcome in breast cancer. Insulin resistance elevates C-peptide levels. Methods: In MA.14, trial patients with stage I or II postmenopausal breast cancer were randomized from September, 1996 until July, 2000 to receive 20 mg tamoxifen PO daily for 5 years with/without the administration of the somatostatin analogue Octreotide LAR 90 mg depot injection monthly for 2 years. Event-free survival (EFS), the trial’s primary outcome measure, was defined as time from randomization to time of recurrence of primary disease, time of second malignancy or death due to any cause. We investigated the effect of baseline IGF-I, IGFBP-3, and C-peptide levels on EFS. Kaplan-Meier univariate and Cox step-wise multivariate regressions were performed with/without adjustment for the stratification factors of adjuvant chemotherapy, nodal status, and hormone receptor status, and included patient age (years) and tumour size (T-status). Results: These results are based on analysis of patient serum for the trial’s 667 patients. Median follow-up for those alive is 6.1 years; patients experienced 165 events. Higher C-peptide levels were associated with significantly worse EFS in adjusted, and unadjusted, univariate and multivariate analyses. Final efficacy analyses are expected within a few months. Updated analyses for the effects of baseline metabolic markers and body mass index on EFS will be presented. Conclusions: This is the largest data set, and the first clinical trial, linking higher serum C-peptide levels to adverse outcome in patients with early breast cancer. These results raise concern in the context of increasing population prevalence of insulin resistance. Potential novel adjuvant therapies exist as insulin resistance is modifiable.

[Table: see text]

Phase II randomized clinical trial of lycopene supplementation before radical prostatectomy

An inverse association has been observed between dietary intake of lycopene and the risk of prostate cancer. We investigated the effects of lycopene supplementation in patients with prostate cancer. Twenty-six men with newly diagnosed, clinically localized (14 T(1) and 12 T(2)) prostate cancer were randomly assigned to receive 15 mg of lycopene (n = 15) twice daily or no supplementation (n = 11) for 3 weeks before radical prostatectomy. Biomarkers of differentiation and apoptosis were assessed by Western blot analysis on benign and malignant parts of the prostate gland. Prostatectomy specimens were entirely embedded, step-sectioned, and evaluated for pathological stage, Gleason score, volume of cancer, and extent of high-grade prostatic intraepithelial neoplasia. Plasma levels of lycopene, insulin-like growth factor-1 (IGF-1), IGF binding protein-3, and prostate-specific antigen were measured at baseline and after 3 weeks of supplementation or observation. Eleven (73%) subjects in the intervention group and two (18%) subjects in the control group had no involvement of surgical margins and/or extra-prostatic tissues with cancer (P = 0.02). Twelve (84%) subjects in the lycopene group and five (45%) subjects in the control group had tumors <4 ml in size (P = 0.22). Diffuse involvement of the prostate by high-grade prostatic intraepithelial neoplasia was present in 10 (67%) subjects in the intervention group and in 11 (100%) subjects in the control group (P = 0.05). Plasma prostate-specific antigen levels decreased by 18% in the intervention group, whereas they increased by 14% in the control group (P = 0.25). Expression of connexin 43 in cancerous prostate tissue was 0.63 +/- 0.19 absorbance in the lycopene group compared with 0.25 +/- 0.08 in the control group (P = 0.13). Expression of bcl-2 and bax did not differ significantly between the two study groups. IGF-1 levels decreased in both groups (P = 0.0002 and P = 0.0003, respectively). The results suggest that lycopene supplementation may decrease the growth of prostate cancer. However, no firm conclusions can be drawn at this time because of the small sample size.

Serum insulin-like growth factor-I (IGF-I) does not correlate positively with isometric strength, fatigue, and quality of life in post-polio syndrome

OBJECTIVES AND BACKGROUND

To determine if serum insulin-like growth factor-I (IGF-I) levels are associated with strength, body mass index (BMI), fatigue, or quality of life in post-poliomyelitis syndrome (PPS). PPS is likely due to a distal disintegration of enlarged post-polio motor units as a result of terminal axonal sprouting. Age-related decline in growth hormone and IGF-I (which support terminal axonal sprouts) is proposed as a contributing factor.

METHODS

As part of the North American Post-Poliomyelitis Pyridostigmine Study (NAPPS), baseline data on maximum voluntary isometric contraction (MVIC), BMI, subjective fatigue (fatigue severity scale, Hare fatigue symptom scale), health-related quality of life (short form health survey-36; SF-36), and serum IGF-I levels were gathered on 112 PPS patients. Pearson correlation coefficients were calculated to evaluate the association between serum IGF-I and MVIC in 12 muscles, BMI, two fatigue scales, and SF-36 scale scores.

RESULTS

There is a significant inverse correlation of IGF-I levels with MVIC in left ankle dorsiflexors (r=-0.30, P<0.01), and left and right knee extensors (r=-0.22, -0.25, P=<0.01, 0.01), but no significant correlations in other muscles. When men and women were evaluated separately, inverse correlations of IGF-I levels with MVIC were found only in men. IGF-I correlated inversely with BMI (r=-0.32, P=0006) and age (r=-0.32, P=0.0005). IGF-I did not correlate with the fatigue or SF-36 scales.

CONCLUSIONS

In this exploratory study, we found that contrary to our expectations, IGF-I did not correlate positively with strength. IGF-I correlated negatively with strength in several lower extremity muscles, BMI, and age. IGF-I is likely not an important factor in the pathogenesis of fatigue and in determining quality of life in PPS, but its role on strength should be studied further.

Vertex balding, plasma insulin-like growth factor 1, and insulin-like growth factor binding protein 3

BACKGROUND

A recent report suggested that men with vertex balding have higher levels of plasma insulin-like growth factor 1 (IGF-1). The association of its major carrier protein, insulin-like growth factor binding protein 3 (IGFBP-3), with male pattern hair loss has not been examined.

OBJECTIVE

We evaluated the relations of plasma concentrations of IGF-1 and IGFBP-3 with vertex balding in middle-aged and elderly men.

METHODS

Participants were 431 male members of the Health Professionals Follow-up Study who responded to a question in 1992 on their hair pattern at 45 years of age and who were 47 to 81 years old when they provided a blood specimen in 1993-1994. Odds ratios (ORs) of vertex balding associated with IGF-1 and IGFBP-3 were estimated from logistic regression models mutually adjusting for each other and controlling for age at blood draw.

RESULTS

Of the 431 men, 128 had vertex balding at age 45. Compared with men who were not balding, for a 1 standard deviation increase in plasma IGF-1 level (72.4 ng/mL), the OR for vertex balding was 1. 31 (95% CI, 0.95-1.81). For a 1 standard deviation increase in plasma IGFBP-3 (957 ng/mL), the OR for vertex balding was 0.62 (95% CI, 0.44-0.88).

CONCLUSION

Older men with vertex balding have lower circulating levels of IGFBP-3 and higher levels of IGF-1 when controlling for IGFBP-3 level.

A prospective study of plasma insulin-like growth factor-1 and binding protein-3 and risk of colorectal neoplasia in women

Insulin-like growth factor-1 (IGF-1) is an important mitogen, and IGF binding protein-3 (IGFBP-3) has opposing effects. Acromegalics, who have abnormally elevated levels of IGF-1, are at increased risk of colorectal tumors. Recent studies have found that IGF-1 levels correlate with risk of prostate cancer and colorectal cancer in men, premenopausal breast cancer in women, and lung cancer in men and women. We examined whether prediagnostic plasma levels of IGF-1 and IGFBP-3 influence risk of colorectal cancer and adenoma in women. From 1989 to 1990, a total of 32,826 women from the Nurses' Health Study provided blood specimens that were archived in liquid nitrogen. During 6 years of follow-up from 1989 to 1994, we documented 79 new cases of colorectal cancer, 90 cases of intermediate/late-stage adenoma (> or =1 cm or tubulovillous/villous histology), and 107 cases of early-stage adenoma (<1 cm and tubular histology). After matching controls (2:1 for cancers and 1:1 for adenomas) to cases by age, month of blood draw, fasting status, and indication for endoscopy (for adenoma controls), plasma IGF-1 and IGFBP-3 levels were measured. Controlling for IGFBP-3 level, relative to women in the low tertile of IGF-1, those in the high tertile were at elevated risk of intermediate/late-stage colorectal neoplasia adenoma [multivariate relative risk (RR), 2.78; 95% confidence interval (CI), 0.76-9.76] and cancer (RR, 2.18; 95% CI, 0.94-5.08). Controlling for IGF-1 level, relative to women in the low tertile of IGFBP-3, women in the high tertile of IGFBP-3 were at lower risk of intermediate/late-stage colorectal adenoma (RR, 0.28; 95% CI, 0.09-0.85) and cancer (RR, 0.28; 95% CI, 0.10-0.83). Neither IGF-1 nor IGFBP-3 had any appreciable relation with early-stage adenoma. These analyses indicate that high levels of circulating IGF-1 and particularly low levels of IGFBP-3 are associated independently with an elevated risk of large or tubulovillous/villous colorectal adenoma and cancer.

Primary node negative breast cancer in BRCA1 mutation carriers has a poor outcome

BACKGROUND

The association between BRCA1 germ-line mutations and breast cancer prognosis is controversial. A historical cohort study was designed to determine the prognosis for women with axillary lymph node negative hereditary breast cancer.

PATIENTS AND METHODS

We tested pathology blocks from 118 Ashkenazi Jewish women with axillary lymph node negative breast cancer for the presence of the two common BRCA1 founder mutations, 185delAG and 5382insC. Patients were followed up for a median of 76 months. Somatic TP53 mutations were screened for by immunohistochemistry, and direct sequencing was performed in the BRCA1-positive tumours.

RESULTS

Sixteen breast cancer blocks (13.6%) carried a BRCA1 mutation. Young age of onset, high nuclear grade, negative estrogen receptor status and over-expression of p53 were highly associated with BRCA1-positive status (P-values all <0.01). BRCA1 mutation carriers had a higher mortality than non-carriers (five-year overall survival, 50% and 89.6%, respectively, P = 0.0001). Young age of onset, estrogen receptor negative status, nuclear grade 3, and over-expression of p53 also predicted a poor outcome. Cox multivariate analyses showed that only germ-line BRCA1 mutation status was an independent prognostic factor for overall survival (P = 0.01). Among nuclear grade 3 tumours, the BRCA1 mutation carrier status was a significant prognostic factor of death (risk ratio 5.8, 95% confidence interval: 1.5-22, P = 0.009). Sequencing of BRCA1-related breast cancers revealed one TP53 missense mutation not previously reported in breast cancer.

CONCLUSIONS

Using a historical cohort approach, we have identified BRCA1 mutation status as an independent prognostic factor for node negative breast cancer among the Ashkenazi Jewish women. Those managing women carrying a BRCA1 mutation may need take these findings into consideration. Additionally, our preliminary results, taken together with the work of others suggest a different carcinogenic pathway in BRCA1-related breast cancer, compared to non-hereditary cases.

Racial variation in insulin-like growth factor-1 and binding protein-3 concentrations in middle-aged men

African-American men have the highest and Asian-American men have the lowest prostate cancer incidence rates in the United States; internationally, rates for the Asian continent are among the lowest. Higher insulin-like growth factor (IGF)-1, which participates in the control of cellular growth and differentiation and is modulated by IGF-binding protein-3 (IGFBP-3), was associated with an increased prostate cancer risk in three recent studies. We, therefore, investigated whether plasma levels of IGF-1 and IGFBP-3 vary by race in United States men selected from among members of the Health Professionals Follow-up Study who were 47-78 years old in 1993-1995 when they provided blood (n = 18,000). All of the men who described their major ancestry as African American (n = 63) and a random sample of 75 Asians and 75 Caucasians were invited to provide a second blood sample in 1997, of whom 42, 52, and 55, respectively, did so. IGF-1 and IGFBP-3 concentrations were determined by ELISA. We used nonparametric methods to assess racial variation in age-adjusted levels. Caucasians had the highest median IGF-1 level (224 ng/ml), followed by Asians (208 ng/ml) and African Americans (205 ng/ml). Median IGFBP-3 concentration was similar between Caucasians and Asians but was more than 13% lower in African Americans. Median molar IGF-1:IGFBP-3 ratio was greatest in Caucasians and lowest in Asians. The lower IGF-1 blood levels relative to IGFBP-3 levels among Asian men are consistent with their lower prostate cancer incidence. Although differences in circulating IGF-1 do not seem to account for the greater prostate cancer risk among African-American men, their absolute lower levels of IGFBP-3 may be contributory.

Prospective study of colorectal cancer risk in men and plasma levels of insulin-like growth factor (IGF)-I and IGF-binding protein-3

BACKGROUND

Insulin-like growth factor-I (IGF-I) is a potent mitogen for normal and neoplastic cells, whereas IGF-binding protein-3 (IGFBP-3) inhibits cell growth in many experimental systems. Acromegalics, who have abnormally high levels of growth hormone and IGF-I, have higher rates of colorectal cancer. We therefore examined associations of plasma levels of IGF-I and IGFBP-3 with the risk of colorectal cancer in a prospective case-control study nested in the Physicians' Health Study.

METHODS

Plasma samples were collected at baseline from 14916 men without diagnosed cancer. IGF-I, IGF-II, and IGFBP-3 were assayed among 193 men later diagnosed with colorectal cancer during 14 years of follow-up and among 318 age- and smoking-matched control subjects. All P values are two-sided.

RESULTS

IGFBP-3 levels correlated with IGF-I levels (r=.64) and with IGF-II levels (r=.90). After controlling for IGFBP-3, age, smoking, body mass index (weight in kg/[height in m]2), and alcohol intake, men in the highest quintile for IGF-I had an increased risk of colorectal cancer compared with men in the lowest quintile (relative risk [RR]=2.51; 95% confidence interval [CI]=1.15-5.46; P for trend = .02). After controlling for IGF-I and other covariates, men with higher IGFBP-3 had a lower risk (RR=0.28; 95% CI=0.12-0.66; P for trend = .005, comparing extreme quintiles). The associations were consistent during the first and the second 7-year follow-up intervals and among younger and older men. IGF-II was not associated with risk.

CONCLUSIONS

Our findings suggest that circulating IGF-I and IGFBP-3 are related to future risk of colorectal cancer.

A randomized trial of tamoxifen alone or combined with octreotide in the treatment of women with metastatic breast carcinoma

BACKGROUND

Tamoxifen (TAM) is generally considered the hormonal agent of choice for postmenopausal women with hormone receptor positive breast carcinoma. The somatostatin analogues, including octreotide, have demonstrated inhibition of breast carcinoma cell lines and multiple endocrinologic actions, including reduction of insulin-like growth factor I (IGF-I), a potent mitogen for breast carcinoma cells. In an attempt to improve the efficacy of TAM, this randomized trial was performed.

METHODS

One hundred thirty-five eligible postmenopausal women with metastatic breast carcinoma were randomized to TAM (10 mg twice daily) alone or combined with octreotide 150 microg (administered subcutaneously thrice daily). The two groups were well balanced, except the TAM group had higher proportions of patients with visceral disease (50% vs. 37%) and a disease free interval longer than 5 years (47% vs. 34%). A cohort of 18 patients was evaluated for the impact of treatment on serum IGF-I, free IGF-I, IGF binding protein 3 levels, and total IGF binding capacity.

RESULTS

The median time to progression was estimated to be 14.2 months with TAM and 10.3 months with TAM plus octreotide. The distribution of progression free survival times revealed no significant difference (P = 0.26), and the progression hazard ratio (TAM/TAM + octreotide) was 0.81 (95% confidence interval [CI], 0.56-1.17). The distribution of survival times revealed no significant difference (P = 0.92), and the death hazard ratio was 0.98 (95% CI, 0.62-1.55). When the 106 patients with measurable or evaluable disease were considered, the objective response rate was 49% with TAM alone and 43% with TAM plus octreotide (P = 0.70). Patients who received TAM plus octreotide had higher incidences of nausea, diarrhea, and steatorrhea. The percentage of decline in serum IGF-I, from pretreatment levels to those following 3-6 weeks of treatment, was significantly greater (P < 0.01) with TAM plus octreotide than with TAM alone.

CONCLUSIONS

There is no indication that the combination of TAM plus octreotide as administered in this study is substantially more efficacious than TAM alone in the treatment of postmenopausal women with metastatic breast carcinoma. The limited cohort included in IGF-I studies suggests that TAM plus octreotide produces a significantly greater reduction in serum IGF-I levels.

Endocrine effects of IGF-I on normal and transformed breast epithelial cells: potential relevance to strategies for breast cancer treatment and prevention

Insulin-like growth factors (IGFs) are mitogenic and anti-apoptotic peptides that influence the proliferative behavior of many cell types, including normal and transformed breast epithelial cells. IGF-I has properties of both a tissue growth factor and a systemic hormone: there is evidence that IGF bioactivity in tissues is influenced not only by local factors such as tissue expression of IGFs, IGF binding proteins (IGFBPs), and IGFBP proteases, but also by factors that regulate whole-body IGF physiology and circulating IGF-I levels. Experimental evidence that interventions that reduce circulating IGF-I levels reduce proliferation of breast neoplasms has raised interest in the possibility of developing novel endocrine therapies that target the growth hormone/IGF-I axis. Furthermore, influences of the growth hormone/IGF-I axis on normal breast epithelial cells may underlie recent epidemiological observations that suggest that premenopausal women with high circulating IGF-I level are at increased risk for breast cancer. These studies suggest that the growth hormone/IGF-I axis deserves investigation as a possible target for novel breast cancer prevention strategies.

Mechanisms of antineoplastic action of somatostatin analogs

Over the past decade, impressive antineoplastic activity of somatostatin analogs has been demonstrated in many tumor models. More recent research has provided information regarding mechanisms underlying the antiproliferative and apoptosis-inducing actions of these compounds. These include both 'direct' mechanisms that are sequellae of binding of somatostatin analogs to somatostatin receptors present on neoplastic cells and 'indirect' mechanisms related to effects of somatostatin analogs on the host. The upregulation of intracellular tyrosine phosphatase activity triggered by binding of ligands to the type II somatostatin receptor has received considerable attention as a direct mechanism, not only because this activity is the converse of the tyrosine kinase activity associated with many peptide mitogen receptors, but also because the type II somatostatin receptor is frequently expressed by common human neoplasms, including breast cancer. The potential importance of indirect mechanisms of action of somatostatin analogs, such as alterations in host insulin-like growth factor physiology, is emphasized by the in vivo antineoplastic activity of these compounds against somatostatin receptor-negative neoplasms. Clinical efficacy and a favorable toxicity profile of somatostatin analogs in the treatment of relatively uncommon conditions such as acromegaly and neuroendocrine tumors have already been demonstrated. Preclinical data now are sufficient to justify controlled clinical trials in breast, prostate, and pancreatic cancer. The development of monthly depot formulations will facilitate the clinical evaluation of somatostatin analogs for these and other indications.

Germ-line BRCA1 mutation is an adverse prognostic factor in Ashkenazi Jewish women with breast cancer

Germ-line mutations in BRCA1 confer an increased risk of developing breast and ovarian cancer, but little is known about the clinical course of breast cancer in BRCA1 mutation carriers compared with noncarriers. Two recurrent BRCA1 mutations (185delAG and 5382insC) are common ( approximately 1.3%) in Ashkenazi Jews and account for about 20% of breast cancers diagnosed before age 40 in this group. We assayed paraffin-embedded tumor blocks from 117 unselected Ashkenazi Jewish women with primary breast cancer, diagnosed before age 65 at a single institution, for the presence of either of the two BRCA1 mutations. We reviewed the medical records and constructed survival curves for BRCA1-positive and -negative subgroups. Twelve of the women (10.3%) were found to carry BRCA1 mutations (eight mutations were 185delAG, and four were 5382insC). The probability of death from breast cancer in the first 5 years was 35.7% in the BRCA1 mutation-positive group and 4.3% in the 100 women without a mutation (P = 0.0023). The 5-year distant disease-free survival was 68.2% in BRCA1 mutation carriers and 88.7% in noncarriers (P = 0.019). These data suggest that breast cancer occurring in an Ashkenazi Jewish woman carrying a germ-line BRCA1 mutation has an adverse prognosis. This information is available before the diagnosis of breast cancer, and therefore, this finding may have important implications for prevention of breast cancer in BRCA1 mutation carriers.

Influence of BRCA1 mutations on nuclear grade and estrogen receptor status of breast carcinoma in Ashkenazi Jewish women

BACKGROUND

In the Ashkenazim, three recurrent germline mutations have been identified in the breast carcinoma susceptibility genes BRCA1 and BRCA2: 185delAG, 5382insC (BRCA1), and 6174delT (BRCA2). The frequency of these mutations in the general Ashkenazi population approaches 2%. There is little available controlled data comparing the characteristics of breast carcinoma arising in BRCA1 mutation carriers or BRCA2 mutation carriers with that arising in noncarriers, although such data would be relevant to the urgent clinical need to develop risk-reduction strategies for individuals at increased risk due to genetic factors.

METHODS

The authors screened 149 unselected tumors arising in Ashkenazi Jewish women for the 185delAG, 5382insC, and 6174delT mutations and compared tumors arising in mutation carriers with tumors arising in noncarriers with respect to nuclear grade, steroid hormone receptor status, and axillary lymph node status.

RESULTS

In the 149 cases, the authors found 17 BRCA1 mutations (11.4%; 95% confidence interval [ci], 6.8-17.6%), and 4 6174delT BRCA2 mutations (2.7%; 95% CI, 0.8-6.7%). Tumors from women with BRCA1 mutations were significantly less likely to be estrogen receptor positive (age-adjusted odds ratio [or]: 0.091; P < 0.001) and more likely to have a high nuclear grade (OR: 5.55; P 0.001) than tumors in which no mutation was identified. All four BRCA2 positive breast carcinoma specimens were estrogen receptor positive.

CONCLUSIONS

Breast carcinoma arising in Ashkenazim BRCA1 mutation carriers has adverse prognostic features relative to those arising in noncarriers in the same population. This may be relevant to the development of prevention and treatment strategies for these women. For example, if tamoxifen reduces the risk of breast carcinoma via its antiestrogenic effects, it is possible that this effect will be diminished in the largely estrogen receptor negative BRCA1-related hereditary breast carcinoma.

The human mammary-derived growth inhibitor (MDGI) gene: genomic structure and mutation analysis in human breast tumors

The mammary-derived growth inhibitor (MDGI) gene is a candidate tumor suppressor gene for human breast cancer. It has been shown to reduce the tumorigenicity of breast cancer cell lines in nude mice, and loss of expression of this gene has been shown in primary breast tumors. Furthermore, the human MDGI gene has been mapped to human chromosome 1p32-p35, a common region of deletion in sporadic breast tumors. We have determined the genomic structure of the human MDGI gene from a cosmid clone mapping to chromosome 1p32-p35 and have more finely mapped the MDGI gene relative to chromosome 1p microsatellite markers. The gene covers approximately 8 kb of genomic DNA and is divided into four exons. In an attempt to identify possible inactivating mutations in the MDGI gene in human breast cancer, we have sequenced all four exons and their surrounding splice junctions in 30 sporadic breast tumors. Ten of these tumors showed loss of heterozygosity (LOH) in the 1p32-p35 region, with 5 tumors showing LOH in the subregion containing the MDGI gene. No mutations were found in this analysis. A polymorphism was identified in exon 2 in the constitutional DNA of 1/30 cases in this study, which resulted in the conversion of a lysine to an arginine residue at codon 53. This variant was present in the constitutional DNA of a further 3/26 women with sporadic breast cancer and 2/90 control individuals (P = 0.20). Despite experimental evidence that MDGI has tumor suppressor activity, our data suggest that mutations in the coding region are uncommon in human breast tumorigenesis.

Insulin-like growth factor binding protein 3 (IGF-BP3) inhibits estrogen-stimulated breast cancer cell proliferation

We have recently demonstrated that exposure of MCF7 cells to antiestrogens in vitro results in both accumulation of IGF-BP3 in media and reduced mitogenic responsivity to IGFs (Cancer Res. 53:5193-5198). We show here that MCF7 cell proliferation in steroid-stripped, serum containing media is significantly attenuated by rhIGF-BP3 (p < 0.05), with a maximal 40% inhibition of serum stimulated growth achieved by 6.25nM IGF-BP3. 10(-10) M estradiol (E2) significantly stimulated MCF7 proliferation, and co-incubation of estrogen containing cultures with 50nM IGF-BP3 resulted in significant attenuation of the estrogen-stimulated proliferation ([3H]thymidine incorporation: E2, 147 +/- 18% of control; E2 +/- IGF-BP3, 111 +/- 18% of control, p < 0.05). These results demonstrate antagonism of steroid stimulated proliferation by an IGF binding protein and are compatible with the hypothesis that antiestrogen-induced accumulation of IGF-BP3 in the conditioned media of MCF7 cells contributes to the cytostatic action of these drugs.

Estrogen and antiestrogen modulation of MCF7 human breast cancer cell proliferation is associated with specific alterations in accumulation of insulin-like growth factor-binding proteins in conditioned media

Many neoplastic cell lines secrete insulin-like growth factor binding proteins (IGFBPs). The physiological role of these proteins is incompletely characterized; under various conditions IGFBPs have been observed to either enhance or inhibit the biological activity of insulin-like growth factors. MCF7 human breast cancer cells are known to be mitogenically responsive to insulin-like growth factors and estrogens, to secrete several IGFBPs, including BP-2, BP-4 and BP-5, and to be growth inhibited by antiestrogens. We report here that the pure antiestrogen ICI 182,780 and, to a lesser extent, the commonly used drug tamoxifen significantly increase levels of a M(r) 43,000-46,000 IGFBP (BP-3) and significantly reduce levels of a M(r) 24,000 IGFBP (BP-4) in the conditioned medium of MCF7 cells. Effects of estradiol and antiestrogens on M(r) 30,000 and M(r) 36,000 IGFBPs are also described. The effects of ICI 182,780 on IGFBPs in the conditioned medium of MCF7 cells may contribute to the remarkable ability of this compound to attenuate insulin-like growth factor I stimulated MCF7 cell proliferation.

Direct effects of tamoxifen on growth hormone secretion by pituitary cells in vitro

There is now strong evidence to suggest that insulin-like growth factor I (IGF-I) plays an important role in breast cancer proliferation. Recently we observed that tamoxifen-treated stage I breast cancer patients have serum IGF-I levels significantly lower than placebo-treated patients. Since IGF-I is growth hormone (GH) dependent, we have tested the hypothesis that tamoxifen alters serum IGF-I levels through direct inhibition of GH secretion. Immature lamb pituitary cultures were examined for acute (3 h) or chronic (1-6 day) effects of the drug, using doses (0.1-10 mumol/l) based on known steady state levels in patients on tamoxifen therapy (0.31-3.1 mumol/l). Tamoxifen had a direct, dose-related, inhibitory effect on GH release from pituitary somatotropes, during acute as well as chronic treatment. The 10 mumol/l dose consistently decreased both basal and growth hormone releasing factor stimulated GH release. These in vitro data are consistent with our hypothesis that tamoxifen suppresses serum IGF-I levels by acting at the pituitary to inhibit GH release.

Tamoxifen reduces serum insulin-like growth factor I (IGF-I)

Antiestrogens are widely used in the management of hormonally responsive breast cancer in both adjuvant and palliative settings, and are currently being evaluated as chemopreventive agents. The classical mechanism of action of these drugs involves inhibition of estrogen-stimulated neoplastic cell proliferation by blockade of estrogen receptors present on breast cancer cells. This paper reviews recent clinical and laboratory data that suggest that the commonly used antiestrogen tamoxifen also acts to reduce serum IGF-I levels. Estrogens appear to play a permissive role in growth hormone (GH) release by the pituitary gland and GH is known to stimulate IGF-I expression by hepatocytes. It is therefore possible that blockade of estrogen receptors in the hypothalamic-pituitary axis by tamoxifen interferes with GH release, leading to reduced hepatic IGF-I expression. In view of results suggesting that IGF-I is a more potent mitogen than estradiol for breast cancer cells and data demonstrating a positive correlation between estrogen receptor level and IGF-I receptor level of breast cancer cells, the IGF-I lowering effect of tamoxifen may contribute to the cytostatic activity of the drug. The interrelationships between steroid hormone physiology and IGF-I physiology may have relevance to a variety of commonly used treatments for hormonally responsive cancers.

Insulinlike growth factor I: a potent mitogen for human osteogenic sarcoma

Insulinlike growth factor I (IGF-I) is among the peptide mitogens that play key roles in the regulation of normal skeletal growth. To investigate the possibility that certain skeletal neoplasms retain a sensitivity to mitogenic stimulation by IGF-I, we studied the effects of this growth factor on human osteosarcoma. Competitive-binding assays and affinity-labeling experiments on membranes prepared from MG-63 immortalized human osteosarcoma cells and primary human osteogenic sarcoma cells demonstrate the presence of specific IGF-I receptors. Furthermore, we show that IGF-I is a potent stimulator of proliferation of MG-63 cells in vitro and is active at concentrations as low as 10(-10) M. A blocking antibody against the IGF-I receptor (alpha-IR3) significantly reduces IGF-I-stimulated proliferation in a dose-dependent manner. These results are consistent with the hypothesis that at least a subset of human osteogenic sarcomas are responsive to IGF-I and indicate that it may be possible to exploit this responsiveness therapeutically.

Somatostatin analogue SMS 201-995 reduces serum IGF-I levels in patients with neoplasms potentially dependent on IGF-I

Tumors of several organs have been shown to bear cell surface receptors for insulin-like growth factor I (IGF-I), and to exhibit dependence on this mitogen for optimum proliferation both in vivo and in vitro. To investigate the feasibility of a novel form of endocrine therapy that would exploit such dependence, we treated 8 patients with non-endocrine solid tumours with the somatostatin analogue SMS 201-995, in an effort to reduce growth hormone-stimulated IGF-I production. Significant decreases in basal and arginine-stimulated serum growth hormone and serum IGF-I were noted. This approach deserves evaluation as a potentially useful form of palliative endocrine therapy for certain cancers.

Characterization of insulin-like growth factor I (IGF-I) receptors of human breast cancer cells

Studies of binding of IGF-I to a plasma-membrane-enriched subcellular fraction prepared from MCF-7 human breast cancer cells reveal the presence of 0.2 pmols specific binding sites for this mitogen per mg membrane protein, with an equilibrium affinity constant of 1.45 nM-1. Competition studies with insulin, IGF-II, and an anti-IGF-I receptor antibody are consistent with the presence of specific IGF-I receptors, and SDS-PAGE showed binding to a 130 kDa subunit identical to that of receptors from human placenta. In addition, we show that IGF-I is more potent than estradiol and comparable to EGF in stimulating in vitro proliferation of MCF-7 cells, and that IGF-I-stimulated proliferation of these cells is inhibited by a blocking monoclonal antibody against the IGF-I receptor. These results demonstrate that IGF-I is an important mitogen for MCF-7 cells and that the mitogenic effect is mediated by specific IGF-I receptors.

Presence of somatomedin receptors on primary human breast and colon carcinomas

Competitive binding techniques were used to study the interaction of insulin-like growth factor I (IGF-I) with a plasma membrane-enriched subcellular fraction purified from primary breast and colon carcinoma specimens obtained at surgery. The presence of specific binding sites for IGF-I was detected in all tumour specimens studied. Scatchard analysis and competition studies with insulin and insulin-like growth factor-II (IGF-II) revealed the presence of specific IGF-I receptors, showing a Kd-value of approximately 2 nM. These results are consistent with the hypothesis that somatomedins play a role in determining the proliferative behaviour of human breast and colon tumors, and suggest that recent laboratory studies showing dependence of neoplastic cells on somatomedins for optimum proliferation may have clinical relevance.

Epidermal growth factor receptor gene-amplified MDA-468 breast cancer cell line and its nonamplified variants

We have recently reported (J. Filmus, M. N. Pollak, R. Cailleau, and R. N. Buick, Biochem. Biophys. Res. Commun. 128:898-905, 1985) that MDA-468, a human breast cancer cell line with a high number of epidermal growth factor (EGF) receptors, has an amplified EGF receptor gene and is growth inhibited in vitro pharmacological doses of EGF. We have derived several MDA-468 clonal variants which are resistant to EGF-induced growth inhibition. These clones had a number of EGF receptors, similar to normal human fibroblasts, and had lost the EGF receptor gene amplification. Karyotype analysis showed that MDA-468 cells had an abnormally banded region (ABR) in chromosome 7p which was not present in the variants. It was shown by in situ hybridization that the amplified EGF receptor sequences were located in that chromosome, 7pABR. Five of the six variants studied were able to generate tumors in nude mice, but their growth rate was significantly lower than that of tumors derived from the parental cell line. The variant that was unable to produce tumors was found to be uniquely dependent on EGF for growth in soft agar.

Amplified, overexpressed and rearranged epidermal growth factor receptor gene in a human astrocytoma cell line

We report here that SK-MG-3, a human astrocytoma cell line with a high number of epidermal growth factor (EGF) receptors, has an amplified and overexpressed EGF receptor gene. Northern blot analysis did not show any abnormal EGF receptor gene-related mRNA species. No amplification or rearrangement was noted in 21 other astrocytoma cell lines. In contrast to other cell lines that have EGF receptor gene amplifications, we have not detected inhibition of in vitro proliferation of the SK-MG-3 line by EGF.

Computer-aided information management systems in clinical trials. A physician's perspective

Clinical trials involve the administration of new or experimental treatments to patients and the subsequent observation of responses to these treatments over appropriate periods of time. During a clinical trial, large volumes of data describing the course of each patient must be gathered and analyzed. Traditionally, computers have been used only for final statistical calculations after labour-intensive data capture and tabulation. These methods are becoming increasingly expensive, and problems with traditional data management techniques in clinical research are compounded by trends including increasing numbers of patients, increasing length of follow-up period, increasing numbers of relevant treatment and response variables, and participation of geographically dispersed research groups in 'multicentre' trials. Existing computer systems to aid with data management in clinical research are reviewed and criticized, and a new system designed to solve data management problems as perceived by the clinical researcher is described.