Results of Two Open-Label, Multicenter Phase II Studies of Docetaxel, Platinum Salts, and Trastuzumab in HER2-Positive Advanced Breast Cancer

BACKGROUND

Preclinical data indicate that docetaxel, platinum salts, and the combination of both drugs are highly synergistic with the anti-HER2 antibody trastuzumab. The University of California at Los Angeles-Oncology Research Network (UCLA-ORN) and the Breast Cancer International Research Group (BCIRG) have conducted two phase II studies to evaluate docetaxel and trastuzumab in combination with either cisplatin or carboplatin for the treatment of women with advanced breast cancer that overexpresses HER2.

METHODS

Each study enrolled 62 patients with HER2-overexpressing tumors. Patients received a median of six cycles of docetaxel at 75 mg/m2 of body surface area and cisplatin (BCIRG 101 study) at 75 mg/m2 or carboplatin (UCLA-ORN study) at AUC = 6 mg/mL. min given on day 1 and then every 21 days. Trastuzumab was given on day 1, cycle 1 (4 mg/kg) and then continued weekly at 2 mg/kg for 1 year or until disease progression. Tumor measurements were obtained at baseline, after three cycles of chemotherapy, and then every 3 months. HER2 gene amplification was determined by fluorescence in situ hybridization.

RESULTS

Patient characteristics were comparable between trials with the exception that 15% of the patients in the UCLA-ORN study had received previous adjuvant taxane therapy. Both regimens were well tolerated, with manageable toxicities. Hematologic toxicities were more frequent in patients in the UCLA-ORN study than in patients in the BCIRG 101 study, whereas the reverse pattern was observed for non-hematologic toxicities. One patient in each study developed reversible congestive heart failure. Responses were observed in 49 of 62 patients in the BCIRG 101 study (overall response rate = 79%, 95% confidence interval [CI] = 66% to 89%) and in 34 of 59 evaluable patients in the UCLA-ORN study (overall response rate = 58%, 95% CI = 44% to 70%). Median times to progression were 9.9 months (95% CI = 8.3 to 13.1 months) and 12.7 months (95% CI = 8.6 to 15.5 months) for patients in the BCIRG 101 and UCLA-ORN studies, respectively. Overall response rates were higher and median time to progression was longer in the subset of patients whose tumors harbored HER2 gene amplification.

CONCLUSION

Combinations of docetaxel, a platinum salt, and trastuzumab are feasible and active in patients with advanced breast cancers that overexpress HER2. The BCIRG is conducting ongoing randomized studies of the three-drug combination in both the metastatic and adjuvant settings.

Phase III trial comparing granulocyte colony-stimulating factor to leridistim in the prevention of neutropenic complications in breast cancer patients treated with docetaxel/doxorubicin/cyclophosphamide: results of the BCIRG 004 trial

This randomized, double-blind, phase III trial compared granulocyte colony-stimulating factor (G-CSF; filgrastim) and leridistim (formerly myelopoietin), a chimeric dual agonist that binds both G-CSF and interleukin-3 receptors, for the prevention of neutropenic complications in patients with breast cancer receiving TAC (docetaxel/doxorubicin/cyclophosphamide) chemotherapy. Patients with metastatic (44%) or localized breast cancer (56%) were randomized to G-CSF 5 microg/kg subcutaneously (s.c.) daily (n = 135), leridistim 5 microg/kg s.c. daily (n = 139), or leridistim 10 microg/kg s.c. every other day alternating with placebo (n = 139). Following administration of TAC (docetaxel 75 mg/m2, doxorubicin 50 mg/m2, cyclophosphamide 500 mg/m2) on day 1, patients received growth factor beginning on day 2 until the postnadir absolute neutrophil count exceeded 1500 cells/ microL. Chemotherapy cycles were repeated every 21 days. The incidence of febrile neutropenia was 7% in the G-CSF arm, 19% in the daily leridistim arm (P = 0.003 for comparison with G-CSF) and 22% in the alternate-day leridistim arm (P < 0.001 for comparison with G-CSF). There was no significant difference between treatment arms in the cumulative percentage of patients experiencing grade 4 neutropenia at some point during therapy (85%-88%). However, grade 4 neutropenia occurred in 53% of cycles in the G-CSF cohort, 61% of cycles in the daily leridistim group (P = 0.063 for comparison with G-CSF), and 63% of cycles in the alternate-day leridistim group (P = 0.015 for comparison with G-CSF). We conclude that G-CSF is superior to leridistim in the prevention of febrile neutropenia in patients with advanced breast cancer receiving TAC chemotherapy. The up-front prophylactic use of G-CSF is a reasonable supportive therapy for patients treated with docetaxel/anthracycline-based combination chemotherapy.

Anastrozole in the management of breast cancer

Anastrozole (Arimidex, AstraZeneca) is a third-generation aromatase inhibitor which rapidly reduces oestradiol concentrations to below detectable levels. It is both potent and selective for the aromatase enzyme, with near-maximal suppression of serum oestrogens occurring at the clinical dose of 1 mg/day in postmenopausal women with advanced breast cancer. Anastrozole has also been shown to be a potent suppressor of intratumoural oestrogens, with responses comparable to those in serum. The results of two large, identically designed, randomised trials in postmenopausal women with advanced breast cancer who had progressed on tamoxifen showed that oral anastrozole 1 mg/day produced a statistically significant survival advantage over megestrol acetate 40 mg q.i.d. The median duration of survival was 26.7 months for anastrozole versus 22.5 months for megestrol acetate. Anastrozole was as well-tolerated as megestrol acetate, while weight gain was significantly increased in the megestrol acetate group compared with the anastrozole group. In another Phase III clinical trial involving 1021 postmenopausal women with advanced breast cancer, anastrozole showed a statistically significant advantage over tamoxifen in median time to progression in a combined analysis of 611 patients who were known to be oestrogen receptor- or progesterone receptor-positive. Anastrozole was as well-tolerated as tamoxifen, with a low rate of withdrawals (2%) due to drug-related adverse events. In addition, anastrozole was associated with fewer thromboembolic events and episodes of vaginal bleeding than tamoxifen. For women with hormone receptor-positive tumours who progress on tamoxifen, anastrozole is superior to megestrol acetate. In addition, anastrozole is a reasonable alternative to tamoxifen for first-line endocrine therapy of advanced breast cancer. Recent data confirm an emerging role for anastrozole as adjuvant therapy for primary breast cancer in postmenopausal patients. Anastrozole is also being investigated in the neoadjuvant setting.

Evidence for the use of chemotherapy in breast cancer

Several distinct historical phases mark the evolution of chemotherapy for breast cancer, including the introduction of single agents in the 1960s, the development of cyclophosphamide, methotrexate, and 5-fluorouracil (CMF)-based regimens in the 1970s, the evaluation of the anthracyclines in the 1980s, and the incorporation of the taxanes in the 1990s. The greatest benefit from the use of standard combination chemotherapy occurs in the adjuvant setting, where absolute improvements in overall survival on the order of 10% have been achieved. In contrast, advances have been more modest in the treatment of metastatic disease, and novel agents and regimens are required for further progress. Of the new cytotoxic drugs introduced in the past decade, the taxanes and capecitabine appear to be the most promising, and have demonstrated activity alone and in combination for the treatment of metastatic disease. The introduction of trastuzumab, an antibody directed against the HER2 receptor protein, heralded the birth of targeted molecular therapy against breast cancer. It is clear that in the near future the further evaluation of trastuzumab combinations and the development of additional molecular agents will propel clinical breast cancer research. One of the main challenges of the new era will be identifying and validating predictive factors so that therapy may be individualized based on tumor biology, rather than empirically selected.

Modulation of omega-3/omega-6 polyunsaturated ratios with dietary fish oils in men with prostate cancer

OBJECTIVES

The results of epidemiologic and animal studies support the role of a low-fat diet supplemented with omega-3 fatty acids contained in fish oil in preventing the development and progression of prostate cancer. As a first step in studying the role of a low-fat, fish oil-supplemented (LF/FOS) diet in a clinical setting, we conducted a prospective study in men with untreated prostate cancer to evaluate whether a 3-month dietary intervention affects the ratio of omega-3 to omega-6 fatty acids in plasma and gluteal fat. In addition, we evaluated the feasibility of studying cyclooxygenase-2 (COX-2) expression in serial prostate needle biopsy specimens before and after the diet.

METHODS

Nine men with untreated prostate cancer consumed an LF/FOS diet for 3 months. Plasma, gluteal adipose tissue, and prostate needle biopsy specimens were obtained from each patient before and after the intervention. The fatty acid compositions of the plasma and gluteal adipose tissue were determined by gas-liquid chromatography, and the COX-2 expression in the prostatic tissue specimens was determined by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

Short-term intervention with an LF/FOS diet caused a significant increase in the omega-3/omega-6 fatty acid ratio in plasma (P = 0.002) and gluteal adipose tissue (P = 0.002) in men with prostate cancer. The COX-2 expression in prostatic tissue was quantitated by RT-PCR in 7 of 9 patients, and COX-2 expression decreased in 4 of these 7 patients.

CONCLUSIONS

A short-term dietary intervention in men with prostate cancer leads to a significant increase in the omega-3/omega-6 fatty acid ratios in plasma and adipose tissue. The potential for this diet to prevent the development and progression of prostate cancer by way of altered COX-2 expression and prostaglandin production in prostatic tissue requires further study.

A multi-institutional phase ii study of SU101, a platelet-derived growth factor receptor inhibitor, for patients with hormone-refractory prostate cancer

In a multi-institutional Phase II trial, we evaluated the efficacy of a platelet-derived growth factor receptor (PDGF-r) inhibitor, SU101, in patients with hormonerefractory prostate cancer. The patients received a 4-day i.v. loading dose of SU101 at 400 mg/m(2) for 4 consecutive days, followed by 10 weekly infusions at 400 mg/m(2). The primary study end points were a decline in prostate-specific antigen (PSA) and a decrease in measurable tumor. Secondary end points were time to progression and an effect on pain as measured by the Brief Pain Survey. Expression of PDGF-r was examined in both metastatic and archival primary prostate tumor samples. Forty-four patients were enrolled at four centers. The median age was 72 years, the median PSA was 223 ng/ml, and 21 patients had at least one prior chemotherapy. Thirty-nine patients are evaluable for PSA, and three patients demonstrated a PSA decline >50% from baseline (55-99.9% decrease). The median time to progression was 90 days. Of 19 patients evaluable for measurable disease, 1 patient had a partial response. Nine of 35 evaluable patients had significant improvement in pain. The most frequent adverse events were asthenia (75%), nausea (55%), anorexia (50%), and anemia (41%). PDGF-r expression was detected in 80% of the metastases and 88% of primary prostate cancers. The results of this trial may warrant further clinical studies with other PDGF-r inhibitors.

Insulin-inducible changes in the relative ratio of PTP1B splice variants

The skeletal muscle activity of protein tyrosine phosphates 1B (PTP1B), a modulator of insulin and IGF-1 signaling, is reduced in obese nondiabetic subjects and in subjects with type 2 diabetes in comparison with leaner, nondiabetic controls. PTP1B mRNA, like many other signaling molecules, including the insulin receptor, is alternatively spliced. Since we have shown that the ratio of the insulin receptor splice variants is modulated by insulin in vitro and is related to insulin levels in vivo, we hypothesized that the relative ratios of the alternatively spliced PTP1B mRNA might also vary in humans in proportion to the degree of hyperinsulinemia. This was tested in 21 nondiabetic Pima Indians, a population at increased risk for obesity and type 2 diabetes. The relative ratio of the PTP1B splice variants was quantified using RT-PCR of total RNA extracted from fractionated monocytes. The ratio of the splice variants was positively correlated with fasting plasma insulin concentration (r = 0.757; P = 0.0001), 2-h plasma insulin concentration following an oral glucose tolerance test (r = 0.614; P = 0.01, n = 16), and percentage of body fat (r = 0.746; P = 0.0001). These data indicate that variability in the ratio of the two splice variants is due, in part, to in vivo levels of chronic hyperinsulinemia. This simple, noninvasive assay is therefore a potential biomarker for chronic hyperinsulinemia, similar to the HbAlc assay in use to monitor glucose management in diabetic patients.

In vitro and in vivo hematopoietic activities of Betafectin PGG-glucan

Betafectin PGG-glucan is a novel beta-(1,3)glucan that has broad-spectrum anti-infective activities without cytokine induction. Here we report that PGG-glucan also has both in vitro and in vivo hematopoietic activities. In vitro studies with bone marrow target cells from the C3H/HeN mouse revealed that although PGG-glucan alone had no direct effect on hematopoietic colony-forming cell (CFC) growth, when combined with granulocyte colony-stimulating factor (CSF) or granulocyte-macrophage CSF, it increased CFC numbers 1.5- to 2.0-fold over those obtained with CSFs alone. Bone marrow cells cultured for high-proliferative-potential CFCs in the presence of interleukin (IL)-1, IL-3, macrophage CSF, and stem cell factor (SCF), or cultured for erythroid burst-forming units in the presence of IL-3, SCF, and erythropoietin, also exhibited enhanced growth in the presence of PGG-glucan. The synergistic effect of PGG-glucan was specific and could be abrogated by anti-PGG-glucan antibody. The ability of PGG-glucan to modulate hematopoiesis in vivo was evaluated in myelosuppressed rodents and primates. C3H/HeN female mice were intravenously administered saline solution or PGG-glucan (0.5 mg/kg) 24 hours before the intraperitoneal administration of cyclophosphamide (200 mg/kg), and the recovery of bone marrow cellularity and granulocyte-macrophage progenitor cells was evaluated on days 4 and 8 after cyclophosphamide treatment. At both time points, enhanced hematopoietic recovery was observed in PGG-glucan-treated mice compared with saline-treated control mice. In a final series of in vivo experiments, we evaluated the ability of therapeutically administered PGG-glucan to enhance hematopoietic recovery in cyclophosphamide-treated cynomolgus monkeys. Monkeys received intravenous infusions of cyclophosphamide (55 mg/kg) on days 1 and 2, followed on days 3 and 10 by intravenous infusion of PGG-glucan (0.5, 1.0, or 2.0 mg/kg). Compared with those in saline-treated monkeys, accelerated white blood cell recovery and a reduction in the median duration of neutropenia were observed in PGG-glucan-treated monkeys. These studies illustrate that PGG-glucan has both in vitro and in vivo hematopoietic activities and that this agent may be useful in the prevention and/or treatment of chemotherapy-associated myelosuppression.

Neurite growth patterns leading to functional synapses in an identified embryonic neuron

We explored the relationship between neurite outgrowth and the onset of synaptic activity in the central neuropil of the leech embryo in vivo. To follow changes in early morphology and the onset of synaptic activity in the same identified neuron, we obtained whole-cell patch-clamp recordings and fluorescent dye fills from dorsal pressure-sensitive (P) cells, the first neurons that could be reliably identified in the early embryo. We followed the development of the P cell from the first extension of neurites to the elaboration of an adult-like arbor. After the growth of primary neurites, we observed a profuse outgrowth of transient neurites within the neuropil. Retraction of the transient neurites left the primary branches studded with spurs. After a dormant period, stable secondary branches grew apparently from the spurs and became tipped with terminals. At this time, neurites of the Retzius (R) cell, a known presynaptic partner in the adult, were observed to apparently contact the terminals. Although voltage-dependent currents were seen in the P cell at the earliest stage, spontaneous synaptic activity was only observed when terminals had formed. Spontaneous release was observed before evoked release could be detected from the R cell. Our results suggest that transient neurites are formed during an exploratory phase of development, whereas the more precisely timed outgrowth of stable neurites from the spurs signals functional differentiation during synaptogenesis. Because spurs have also been observed in neurons of the mammalian brain, they may constitute a primordial synaptic organizer.

Expression of the c-kit proto-oncogene and its ligand stem cell factor (SCF) in normal and malignant human testicular tissue

Recent findings suggest an important role of the proto-oncogene c-kit, a surface membrane receptor of the tyrosine kinase family, and its ligand stem cell factor (SCF) in normal spermatogenesis and possibly in the pathogenesis of certain testicular germ cell tumors. To further investigate this potential role, the expression of c-kit and SCF was studied in normal and malignant human testicular tissue specimens at the mRNA and protein level by Northern blot analysis and immunohistochemistry, respectively. The detection of the c-kit receptor in normal human germ cells and its natural ligand SCF in Sertoli cells suggests the presence of a local trophic regulatory system that may be active in human spermatogenesis. Additionally, c-kit expression was detected in the seminoma but not in the nonseminoma subtype of human testicular germ cell tumors (GCT). Stem cell factor was not expressed at the mRNA level in tissue from either subtype of GCT as determined by Northern blot analysis; however, the protein was detected immunohistochemically in the cytoplasm of rare tumor cells.

Insulin-inducible changes in insulin receptor mRNA splice variants

Alternative splicing of insulin receptor pre-mRNA has been shown to be regulated in a tissue-specific and developmental manner. We investigated whether the receptor ligand might regulate the relative distribution of alternatively spliced mRNA in insulin-sensitive cells and found that changes in the relative expression of the two alternatively spliced insulin receptor RNA isotypes expressed in hepatocytes are regulated by insulin. In addition, we observed significant differences (p < or = 0.001) in insulin receptor isotype expression in subjects who were hyperinsulinemic and insulin-resistant versus subjects who were insulin-sensitive. These results support a role for insulin in the regulation of the relative expression of alternatively spliced mRNA expressed in insulin-responsive cells and tissues.

Pursuit eye movements in late-onset esotropia

Horizontal, smooth pursuit eye movements were recorded from adults and children with infantile and late-onset esotropia using a remote, video-based, eye-movement recording system. Each subject monocularly tracked a 0.5-degree target moving back and forth on a video monitor at a constant velocity of 10 degrees, over a range of 12 degrees. Each subject's nasal and temporal gain (eye velocity/target velocity) was measured. Confirming the results of previous studies, we found that infantile esotropes had asymmetrical pursuit eye movements (nasal gain greater than temporal gain) while late-onset esotropes had symmetrical gains. However, unlike previous investigators, we found that half of the late-onset esotropes had impaired pursuit gain. The magnitude of the pursuit abnormality and the amount of refractive error were correlated--patients with the highest refractive error had the lowest pursuit gain.