Citations

Abstract Preclinical investigations have identified insulin-like growth factor (IGF) signaling as a key mechanism for cancer growth and resistance to clinically useful therapies in multiple tumor types including breast cancer. Thus, agents targeting and blocking IGF signaling have promise in the treatment of solid tumors. To identify possible mechanisms of resistance to blocking the IGF pathway, we generated a cell line that was resistant to the IGF-1R/InsR benzimidazole inhibitors, BMS-554417 and BMS-536924, and compared expression profiles of the parental and resistant cells lines using Affymetrix GeneChip Human Genome U133 arrays. Compared with MCF-7 cells, breast cancer resistance protein (BCRP) expression was increased 9-fold in MCF-7R4, which was confirmed by immunoblotting and was highly statistically significant (P = 7.13E-09). BCRP was also upregulated in an independently derived resistant cell line, MCF-7 924R. MCF-7R4 cells had significantly lower intracellular accumulation of BMS-536924 compared with MCF-7 cells. Expression of BCRP in MCF-7 cells was sufficient to reduce sensitivity to BMS-536924. Furthermore, knockdown of BCRP in MCF-7R4 cells resensitized cells to BMS-536924. Four cell lines selected for resistance to the pyrrolotriazine IGF-1R/InsR inhibitor, BMS-754807, did not have upregulation of BCRP. These data suggest that benzimidazole IGF-1R/InsR inhibitors may select for upregulation and be effluxed by the ATP-binding cassette transporter, BCRP, contributing to resistance. However, pyrrolotriazine IGF-1R/InsR inhibitors do not appear to be affected by this resistance mechanism. Mol Cancer Ther; 10(1); 117–25. ©2011 AACR.

Abstract Background: The Preoperative Endocrine Prognostic Index (PEPI) scores the independent prognostic effects of tumor pathologic staging and expression levels of ER and the “proliferation” marker Ki67 in the surgical sample to predict long term outcomes after completion of neoadjuvant endocrine treatment (Ellis et al JNCI 100:1380, 2008). A limitation of the PEPI is that the prognostic information becomes available only after 4 months of treatment. We therefore evaluated the value of an early assessment of the Ki67 level in a tumor biopsy sample taken two to four weeks after initiating treatment in two neoadjuvant endocrine therapy trials for the purposes of the early identification of non- respondersMethods: A Ki67 cut point of greater than 10% for poor outcome in ER+ breast cancer was derived by comparing the PAM50 intrinsic subtype profile using a qRT-PCR assay with Ki67 data in a 700+ sample data set. A baseline level of 10% or less correlated most closely with a PAM50-based definition of LumA breast cancer and above 10% LumB breast cancer. We subsequently applied the 10% cut point to the baseline and early on-treatment Ki67 data in two trials, POL (Olson et al JACS 208:906, 2009) and IMPACT (Smith et al JCO: 23, 5108, 2005).Results: At baseline the dichotomized Ki67 definition was not significantly predictive for surgical Ki67 level, PEPI score or RFS in this modest size sample set. In contrast, in a result that emphasizes the enhaced prognostic properties of the on-treatment Ki67 approach, the one month POL sample Ki67 values (62 patients) predicted a higher level of Ki67 in the surgical samples at four months after treatment initiation (P=.01), a poorer PEPI score (P=0.01), a smaller number of patients in the PEPI risk point zero group (P=0.08) and worse relapse free survival (P=0.003). The IMPACT data (153 patients) confirmed that a two week Ki67 >10% predicted higher Ki67 in the surgical specimen (P=0.001), a poorer PEPI score (P=0.001), smaller numbers of patients in the PEPI 0 risk point group (P= 0.004) and worse relapse free survival (P=0.008).Ki67 and OutcomePOL 4W Ki67% PEPI 0RFS (events)10%>1/19 (5%)5/21 (23%)10%≤10/36 (28%)1/41 (2.4%)P ValueP=0.08 (Fisher)P=0.003 (log rank)IMPACT 2W Ki67% PEPI 0RFS (events)10%>0/32 (0%)9/35 (26%)10%≤21/101 (21%)13/118 (11%)P ValueP=0.004 (Fisher)P=0.008 (log rank) Conclusions: A tumor Ki67 assessment taken a short time (2 to 4 week window) after the initiation of neoadjuvant AI identifies patients with poor outcome ER+ disease. Amendment 6 of the neoadjuvant endocrine therapy protocol ACOSOG Z1031 will triage patients with an “on treatment” Ki67 value above 10% to chemotherapy in order to assess the pathological response rate to cytotoxic therapy in this important tumor subset.Supported by R01 CA095614, Avon PFP award 3P50 CA68438-07S2, U01 CA114722, ACOSOG U10 CA 76001, Breakthrough Cancer UK and AstraZenica (IMPACT trial). Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 78.

Abstract BackgroundRIBBON-1, a Phase III, multicenter, randomized, placebo-controlled trial in patients with previously untreated MBC was designed to evaluate the efficacy and safety of adding bevacizumab (B) to chemotherapy regimens including capecitabine (Cape; n=615); a taxane (T; n=307), or an anthracycline (Anth; n=315) compared with chemotherapy alone. Pre-specified analyses of progression-free survival PFS) in the Cape and pooled T/Anth cohorts, the primary endpoints of the study were increased upon addition of B. In the Cape cohort, median PFS increased from 5.7 to 8.6 mo (HR=0.69, p-value=0.0002) and in the T/Anth cohort, it increased from 8.0 to 9.2 mo (HR=0.64; p-value<0.0001).MethodsRECIST was used to determine objective response rate (ORR). Patients without a post-baseline tumor assessment were considered non-responders. The primary analysis for the ORR and the duration of response was performed using only patients with measurable disease at baseline. ORR was formally compared between the two treatment arms using the Mantel-Haenszel Chi-squared test, using the randomization stratification factors. Fisher's exact test was also performed. Clinical benefit rate (CBR) was defined as the proportion of patients with a complete or partial response or with stable disease at Week 24. Exploratory analyses of CBR and time to response are provided here. Summary statistics of time to response at Week 9 will be presented as will the final analysis of the secondary endpoint of overall survival.ResultsAnalyses of ORR and CBR are provided in the following table. CapeTaxaneAnth PL (n=206)B (n=409)PL (n=104)B (n=203)PL (n=103)B (n=212)Patients with measurable disease, n (%)161 (78.2)325 (61.1)85 (81.7)161 (79.3)92 (89.3)184 (86.8)ORR, %23.635.435.350.340.252.2CR, n (%)1 (0.6)7 (2.2)3 (3.5)4 (2.5)2 (2.2)3 (1.6)PR, n (%)37 (23.0)108 (33.2)27 (31.8)77 (47.8)35 (38.0)93 (50.5)Difference between arms, %11.815.012.0p-value, unstratified0.00940.030.073Duration of ORMedian, mo7.29.28.68.46.08.1HR (95% CI)0.61 (0.39–0.96)0.75 (0.45–1.27)0.53 (0.34–0.83)Log-rank p-value0.03260.2840.0047Clinical benefit rate*, %47.164.365.471.969.980.7p-value, unstratified<0.00010.240.04CR+PR at Week 9, %20.229.438.354.544.451.1B=bevacizumab, cape=capecitabine, CI=confidence interval, HR=hazard ratio, OR=objective response, PL=placebo, T/Anth=taxane/anthracycline.*For randomized patients.ConclusionsIn patients with HER2-negative MBC, the addition of bevacizumab to capecitabine, taxane or anthracycline chemotherapy induces more responses and those responses occur more rapidly. For capecitabine and anthracycline the addition of bevacizumab leads to objective responses that last longer. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6084.

Abstract Background: Postmenopausal women with significant osteopenia/osteoporosis are at increased risk of fracture, a risk that is exacerbated by the use of Aromatase Inhibitors (AIs). Bisphosphonates may be used for these patients because there is no known interaction with estrogen and/or progesterone receptors (ER, PR). This study evaluated the concurrent use of zoledronic acid in patients with significant osteopenia or osteoporosis who received initial adjuvant letrozole therapy for primary BC, to determine if further bone mineral density (BMD) loss could be prevented.Methods: Postmenopausal women with Stage I-IIIa, ER and/or PR + BC, no evidence of metastatic disease, and a BMD T-score < -2.0 were treated with daily letrozole 2.5 mg/d, vitamin D 400 international units/d, calcium 500 mg twice daily, and 4 mg I.V. zoledronic acid every 6 months (for 5 years). The BMD was measured at baseline and at one year. Kruskall-Wallis p-value methodology was used as the method of statistical analysis. Since this was a single-arm study, the analysis plan was primarily descriptive. The primary endpoint was the mean change in lumbar spine (LS) BMD at 1 year.Results: 60 patients were enrolled; 46 completed 1 year of treatment. Mean patient age was 67 years, with 44% having taken prior tamoxifen. At 1 year (see figure 1), LS BMD increased 2.66% (p=0.01), femoral neck (FN) BMD increased 4.81% (p=0.01), and any measured endpoint (within the LS or FN) increased 4.55% (p=0.0052). 7% of patients experienced a fracture vs.13% with a pre-existing history of fracture before enrollment. No patients had disease recurrence during year 1. Toxicity was minimal with arthralgia as the most common complaint. There were no reports of osteonecrosis of the jaw.Conclusion: Zoledronic acid prevents additional bone loss in postmenopausal women with significant osteopenia or osteoporosis initiating letrozole. Treatment with zoledronic acid was associated with an improvement in BMD. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2103.

Abstract Abstract #6140 Background:
 Ixabepilone (ixa), the first in a new class of antineoplastic agents, showed clinical benefit in combination with capecitabine (C) in 2 large clinical trials in metastatic breast cancer (MBC) pts whose tumors were resistant to (study 046, JCO, 2007) or pretreated with anthracycline (A) and taxanes (T) (study 048). In 048, ixa + C, compared to C alone, demonstrated significant increases in PFS (HR 0.79 [0.69-0.90]) and ORR (43% vs 29%). A trend toward increased OS was seen both in 048 (HR 0.90 [0.78-1.03]) and in 046 (HR 0.90 [0.77-1.05]), which did not reach statistical significance. Similar to taxanes, dose-limiting peripheral neuropathy (PN) is a side effect associated with ixa treatment. Here we present the incidence rates, management of ixa-induced PN from 3 registrational studies in pts with MBC and an analysis of resolution time. Also, data on potential risk factors for PN are presented.
 Methods:
 Incidence of PN is summarized from a 2000 pt program from 3 multi-center clinical trials. In this program, almost 1100 pts with MBC received ixa either as a monotherapy (40 mg/m2 IV over 3h Q3w, N=126) in a phase II study, or in combination with C (1000 mg/m2 PO BID x14d Q3w) in 2 large phase III studies (N = 369 and N = 595). PN was evaluated every 4 weeks after completion of treatment until toxicity was resolved. Resolution of PN was defined as the time from onset of worst grade to baseline or grade 1. A Cox regression analysis was also performed on a dataset of 945 pts with different tumor types across multiple studies, receiving ixa as a monotherapy or in combination with C, to identify the potential risk factors for grade 3/4 PN.
 Results:
 Incidence rates of grade 3/4 PN and resolution time observed in 1 phase III study (046) and the phase II (081) have been published before (081: JCO, 25; 3407). Here we present the data from the final confirmatory phase III study (048).
 
 PN was effectively managed with dose reduction. After dose reduction, symptoms improved or did not worsen in the majority of pts, and a median of 2-3 additional treatment cycles were delivered. Pts with diabetes were at a higher risk of grade 3/4 PN (HR: 1.67 [1.00-2.78], p-value = 0.049).
 Conclusions:
 Incidence of ixa-associated PN was similar to that observed in trials of other T based regiments. Ixa-induced PN has a predictable median time to resolution of 5-6 weeks over 3 large studies. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6140.

Abstract Abstract #2149 Background: Inhibitors of the insulin-like growth factor 1 receptor (IGF-1R) are currently undergoing clinical testing. Preclinical investigations have identified IGF-1 signaling as a key mechanism for breast cancer growth and resistance to clinically useful therapies, including tamoxifen and trastuzumab. Thus, agents targeting IGF-1R have promise in the treatment of breast cancer. Determining mechanisms that can confer resistance to these agents may aid their clinical development.
 Methods: To understand factors may be important in predicting sensitivity to targeting the IGF-1 signaling pathway, we developed a cell line (MCF-7R4) that is resistant to BMS-554417, a small molecule, dual-kinase inhibitor of IGF-1R and insulin receptor (InsR). Compared with the parental MCF-7 cells, MCF-7R4 cells are 40- to 50-fold resistant to BMS-554417 and cross-resistant to the similar compound BMS-536924. The expression profiles of MCF-7R4 and that of MCF-7 were compared using Affymetrix GeneChip Human Genome U133 Plus 2.0 Arrays. Intracellular concentrations of BMS-536924 were examined by reverse phase high performance liquid chromatography. BMS-536924 cellular accumulation in vitro was visualized by fluorescence microscopy using a DAPI filter set. MCF-7 cells stably transfected with either the empty mammalian expression vector pcDNA (MCF-EV) or full length BCRP (MCF-BCRP) were examined for sensitivity to BMS 536924 by MTS assays.
 Results: Compared to MCF-7 cells, BCRP expression was increased 9-fold in MCF-7R4, which was highly statistically significant by t-test (p= 7.13E-09). Little change was observed in other ABC transporter proteins, including ABCB1. No change was observed in IGF-1R or InsR expression. BCRP overexpression in MCF-7R4 cells was confirmed by western blotting. MCF-7R4 cells had significantly lower intracellular accumulation of BMS-536924 compared to MCF-7 cells. Confirming these results, MCF-BCRP cells were significantly less sensitive to the cytoxic effects of BMS-536924 cells than MCF-EV cells.
 Conclusions: BCRP expression was stimulated by prolonged exposure of MCF-7 cells to BMS-554417. Upregulation of BCRP is one of the most significant changes observed in MCF-7R4 cells in comparison to parental cells. BCRP expression decreased cellular exposure to BMS-536924 and was sufficient to confer resistance. These data suggest that BSM-536924 is a substrate for BCRP-mediated efflux. Expression of BCRP may be important in de novo and acquired resistance to benzimidazole –based inhibitors of IGF-1R/InsR. Supported in part by the Mayo Clinic Breast SPORE (CA116201-03), NIH K12 (CA090628-05) and the Mayo Clinic Cancer Center (CA15083). Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2149.

Purpose Cumulative sensory neurotoxicity (sNT) is the dose-limiting toxicity of oxaliplatin, which commonly leads to early discontinuation of oxaliplatin-based therapy in the palliative and adjuvant settings. In a nonrandomized, retrospective study, intravenous (IV) calcium/magnesium (Ca/Mg) was associated with reduced oxaliplatin-induced sNT. Methods Patients with colon cancer undergoing adjuvant therapy with infusional fluorouracil, leucovorin, and oxaliplatin (FOLFOX) were randomly assigned to Ca/Mg (1g calcium gluconate plus 1g magnesium sulfate pre- and post-oxaliplatin) or placebo, in a double-blinded manner. The primary end point was the percentage of patients with grade 2 or greater sNT at any time during or after oxaliplatin-based therapy by National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE; version 3) criteria. An oxaliplatin-specific sNT scale and patient questionnaires were also used to assess sNT. After 104 of 300 planned patients were enrolled, the study was closed. This was due to preliminary reports from another trial that suggested that Ca/Mg decreased treatment efficacy; these data were subsequently found to be incorrect. Results Overall, 102 patients were available for analysis. Ca/Mg decreased the incidence of chronic, cumulative, grade 2 or greater sNT, as measured by NCI CTCAE (P = .038) and also by the oxaliplatin-specific sNT scale (P = .018). In addition, acute muscle spasms associated with oxaliplatin were significantly reduced (P = .01) No effect on acute, cold-induced sNT was found. No substantial differences in adverse effects were noted between Ca/Mg and placebo. Conclusion Despite early termination and decreased statistical power, this study supports IV Ca/Mg as an effective neuroprotectant against oxaliplatin-induced cumulative sNT in adjuvant colon cancer.

Purpose Functional iron deficiency may impair response to erythropoiesis-stimulating agents (ESAs) in iron-replete patients with chemotherapy-associated anemia (CAA). This study evaluated whether coadministration of parenteral iron improves ESA efficacy in patients with CAA. Patients and Methods This prospective, multicenter, randomized trial enrolled 502 patients with hemoglobin (Hb) less than 11 g/dL who were undergoing chemotherapy for nonmyeloid malignancies. All patients received darbepoetin alfa once every 3 weeks and were randomly assigned to receive either ferric gluconate 187.5 mg intravenously (IV) every 3 weeks, oral daily ferrous sulfate 325 mg, or oral placebo for 16 weeks. Results There was no difference in the erythropoietic response rate (ie, proportion of patients achieving Hb ≥12 g/dL or Hb increase ≥ 2 g/dL from baseline): 69.5% (95% CI, 61.9% to 76.5%) of IV iron-treated patients achieved an erythropoietic response compared with 66.9% (95% CI, 59.1% to 74.0%) who received oral iron and 65.0% (95% CI, 57.2% to 72.3%) who received oral placebo (P = .75). There were also no differences in the proportion of patients requiring red cell transfusions, changes in quality of life, or the dose of darbepoetin administered. Adverse events (AEs) tended to be more common in the IV iron arm: grade 3 or higher AEs occurred in 54% (95% CI, 46% to 61%) of patients receiving IV iron compared with 44% (95% CI, 36% to 52%) who received oral iron and 46% (95% CI, 38% to 54%) who received oral placebo (P = .16). Conclusion In patients with CAA, addition of IV ferric gluconate to darbepoetin failed to provide additional benefit compared with oral iron or oral placebo.