beta-Tubulin mutations are associated with resistance to 2-methoxyestradiol in MDA-MB-435 cancer cells.

2-Methoxyestradiol is an estradiol metabolite with significant antiproliferative and antiangiogenic activity independent of estrogen receptor status. To identify a molecular basis for acquired 2-methoxyestradiol resistance, we generated a stable 2-methoxyestradiol-resistant (2ME2R) MDA-MB-435 human cancer cell line by stepwise exposure to increasing 2-methoxyestradiol concentrations. 2ME2R cells maintained in the presence of the drug and W435 cells maintained in the absence of the drug showed 32.34- to 40.07-fold resistance to 2-methoxyestradiol. Cross-resistance was observed to Vinca alkaloids, including vincristine, vinorelbine, and vinblastine (4.29- to 6.40-fold), but minimal resistance was seen to colchicine-binding agents including colchicine, colcemid, and AVE8062A (1.72- to 2.86-fold). No resistance was observed to paclitaxel and epothilone B, polymerizing agents (0.89- to 1.14-fold). Genomic sequencing identified two different heterozygous point mutations in the class I (M40) isotype of beta-tubulin at amino acids 197 (Dbeta197N) and 350 (Kbeta350N) in 2ME2R cells. Tandem mass spectrometry confirmed the presence of both wild-type and the mutant beta-tubulin in 2ME2R cells at the protein level. Consistently, treatment of parental P435 cells with 2-methoxyestradiol resulted in a dose-dependent depolymerization of microtubules, whereas 2ME2R cells remained unaffected. In contrast, paclitaxel affected both cell lines. In the absence of 2-methoxyestradiol, 2ME2R cells were characterized by an elevated level of detyrosination. Upon 2-methoxyestradiol treatment, levels of acetylated and detyrosinated tubulins decreased in P435 cells, while remaining constant in 2ME2R cells. These results, together with our structure-based modeling, show a tight correlation between the antitubulin and antiproliferative effects of 2-methoxyestradiol, consistent with acquired tubulin mutations contributing to 2-methoxyestradiol resistance.

When not to treat--chemotherapy for small (< or = 1 cm) breast cancers.

The role of adjuvant chemotherapy in treatment of breast cancers < or = 1.0 cm is controversial. Careful consideration must be given to the patient's overall risk of recurrence and death given her tumor size and lymph node status. Studies indicate that overall survival for women with lymph node-negative breast cancers < or = 1.0 cm is 90-99%. Given the known relative benefit of adjuvant chemotherapy for breast cancer, the absolute benefit of chemotherapy in this setting is usually < or = 1%. The toxicities of adjuvant chemotherapy, including cognitive dysfunction, early menopause, cardiac dysfunction, and leukemia, are significant to patients. The decision to treat women who are already at a very low risk of recurrence with adjuvant chemotherapy must involve an honest and detailed discussion between the patient and her oncologist.

Predicting response to primary chemotherapy: gene expression profiling of paraffin-embedded core biopsy tissue.

PURPOSE: Primary chemotherapy provides an ideal opportunity to correlate gene expression with response to treatment. We used paraffin-embedded core biopsies from a completed phase II trial to identify genes that correlate with response to primary chemotherapy. PATIENTS AND METHODS: Patients with newly diagnosed stage II or III breast cancer were treated with sequential doxorubicin 75 mg/M2 q2 wks x 3 and docetaxel 40 mg/M2 weekly x 6; treatment order was randomly assigned. Pretreatment core biopsy samples were interrogated for genes that might correlate with pathologic complete response (pCR). In addition to the individual genes, the correlation of the Oncotype DX Recurrence Score with pCR was examined. RESULTS: Of 70 patients enrolled in the parent trial, core biopsies samples with sufficient RNA for gene analyses were available from 45 patients; 9 (20%) had inflammatory breast cancer (IBC). Six (14%) patients achieved a pCR. Twenty-two of the 274 candidate genes assessed correlated with pCR (p < 0.05). Genes correlating with pCR could be grouped into three large clusters: angiogenesis-related genes, proliferation related genes, and invasion-related genes. Expression of estrogen receptor (ER)-related genes and Recurrence Score did not correlate with pCR. In an exploratory analysis we compared gene expression in IBC to non-inflammatory breast cancer; twenty-four (9%) of the genes were differentially expressed (p < 0.05), 5 were upregulated and 19 were downregulated in IBC. CONCLUSION: Gene expression analysis on core biopsy samples is feasible and identifies candidate genes that correlate with pCR to primary chemotherapy. Gene expression in IBC differs significantly from noninflammatory breast cancer.

Randomized phase II trial of the anti-angiogenic potential of doxorubicin and docetaxel; primary chemotherapy as Biomarker Discovery Laboratory.

PURPOSE: Primary chemotherapy provides an ideal opportunity to correlate potential non-invasive surrogate markers of angiogenesis with tumor microvessel density (MVD) and response. PATIENTS AND METHODS: Patients with newly diagnosed stages II or III breast cancer were treated with sequential doxorubicin 75 mg/M2 q2 wks x 3 and docetaxel 40 mg/M2 weekly x 6; treatment order was randomly assigned. Potential serologic and imaging markers of angiogenesis were obtained pre-treatment, at crossover and completion of chemotherapy. Non-invasive biomarkers were correlated with MVD and pathologic response. RESULTS: From June 1999 to October 2002, 70 patients were entered. Median pretreatment tumor diameter was 6.0 cm with clinically involved axillary nodes in 33 (47%) patients; 20% had inflammatory disease. Clinical response rate was 91%, including 46% clinical complete responses. Pathologic complete response (pCR) was confirmed in 9 (12.8%) patients. Baseline MVD did not correlate with clinical or pathologic response. Serologic markers were obtained in all patients; basic fibroblast growth factor (bFGF) was lower at baseline and increased during treatment in patients with a pCR but did not correlate with MVD. Color Doppler ultrasound (CDUS) was completed in 47 patients; no parameter reliably correlated with MVD or response. Positron emission tomography (PET) with [F-18]-fluoro-deoxyglucose, [O-15]-water and [C-11]-carbon monoxide were completed in 19 patients; uptake of all tracers decreased during treatment in virtually all patients. CONCLUSION: Sequential doxorubicin and docetaxel is generally well tolerated and highly active. Serum angiogenic factors and imaging parameters frequently varied throughout treatment but did not correlate with MVD or consistently predict response.

A phase II study of 9-nitro-camptothecin in patients with previously treated metastatic breast cancer.

AIMS: This Phase II study was conducted to determine the efficacy and toxicity of 9-nitro-camptothecin (9-NC) in patients with previously treated metastatic breast cancer. Pharmacokinetic samples were obtained to investigate the correlation of plasma 9-NC exposure with clinical response and toxicity. PATIENTS AND METHODS: Eligible patients had histologically confirmed metastatic breast cancer with measurable or evaluable disease. Patients must have received one or two prior chemotherapy regimens for metastatic disease. 9-NC was given orally, 1.5 mg/m(2)/day for 5 days each week; response was assessed every 8 weeks. Pharmacokinetic samples were obtained on day 1 of weeks 1 and 5. RESULTS: Eighteen patients were enrolled between September 1999 and May 2000; seventeen patients were evaluable for response. The most common toxicities were nausea, vomiting, urinary symptoms, fatigue and diarrhea. No objective responses were observed; six patients had stable disease. 9-NC apparent clearance ranged from 0.57 to 55.08 L/h (median 5.91 L/h); 9-NC area under the curve ranged from 38 to 2130 ng/ml x h (median 377 ng/ml x h). There was no relationship between pharmacokinetic parameters and individual patient toxicity. CONCLUSION: 9-NC has limited activity in patients with previously treated metastatic breast cancer. Though 9-NC has substantial pharmacokinetic variability in this patient population; no correlation was found between pharmacokinetic variables and toxicity.