Ultrasound image-based endoscope localization for minimally invasive fetoscopic surgery

The purpose of this work is to introduce an ultrasound image-based intraoperative scheme for rigid endoscope localization during minimally invasive fetoscopic surgery. Positional information of surgical instruments with respect to anatomical features is important for the development of computer-aided surgery applications. While most surgical navigation systems use optical tracking systems with satisfactory accuracy, there are several operation limitations in such systems. We propose an elegant framework for intraoperative instrument localization that does not require any external tracking system but uses an ultrasound imaging system and a computation scheme based on constrained kinematics of minimally invasive fetoscopic surgery. Our proposed algorithm simultaneously estimates endoscope and port positions in an online sequential fashion with standard deviation of 1.28 mm for port estimation. Robustness of the port estimation algorithm against external disturbance was demonstrated by intentionally introducing artificial errors to measurement data. The estimation converges within eight iterations under disturbance magnitude of 30 mm.

Abstract P3-12-03: Combined targeting of HER2 and VEGFR2 for effective treatment of HER2-amplified breast cancer brain metastases

Brain metastases remain a serious obstacle in the treatment of patients with human epidermal growth factor receptor-2 (HER2)-amplified breast cancer. Unlike HER2-amplified breast tumors growing in extra-cranial locations, brain metastases do not respond well to HER2 inhibitors and are often the reason for treatment failure. One of the major challenges in studying brain metastases is the lack of preclinical models. We developed a HER2-amplified mouse model of brain metastasis using an orthotopic xenograft of BT474 cells in mice. As seen in patients, the HER2 inhibitors trastuzumab and lapatinib failed to contain brain metastatic tumor growth.

Based on previous findings from our laboratory suggesting a role of vascular endothelial growth factor (VEGF) in the resistance of HER2-overexpressing breast cancer brain metastases to trastuzumab, we combined HER2 inhibitors with the anti-VEGFR2 antibody DC101. The combination of either trastuzumab and DC101 or lapatinib and DC101 significantly slowed metastatic tumor growth in the brain, and resulted in a striking improvement in overall survival. The benefit is due largely to an anti-angiogenic effect. The combination of anti-HER2 and anti-VEGFR2 therapy reduced both the total and functional microvascular density in the brain metastatic tumors. Moreover, tumor tissues under combination therapy showed a marked increase in necrosis.

Preclinical and clinical evidence suggest that the combination of trastuzumab and lapatinib is superior to either agent alone – though this has never been tested in the brain metastatic setting. We consistently observed increased phosphorylation of HER2 in breast tumor cells growing in the brain compared with the mammary fat pad. In addition, while short-term lapatinib treatment significantly reduced HER2 activation in the brain, it could do so only to the level of that observed in the untreated mammary fat pad - and this effect disappeared over time. We hypothesized that more pronounced HER2 inhibition would be beneficial to these brain metastases with increased HER2 activation. We show here a significant growth delay with the combination of the two HER2 inhibitors compared with monotherapy. Moreover, we found a dramatic brain metastatic tumor growth delay in mice treated with both HER2 inhibitors, trastuzumab and lapatinib, and DC101. The triple combination prolonged overall survival 5 times longer than control-treated mice.

Brain metastasis from breast cancer is considered the “final frontier” of breast cancer research and treatment. Our findings support the clinical development of a three-drug regimen of trastuzumab, lapatinib and a VEGF pathway inhibitor for the treatment of HER2-amplified breast cancer brain metastases. While the anti-VEGF antibody bevacizumab in combination with trastuzumab and chemotherapy has shown some promise in HER2-positive metastatic breast cancer patient, there are no data on its efficacy in the context of brain metastases. A clinical trial is now recruiting patients to evaluate the efficacy of bevacizumab in breast cancer patients with active brain metastases, including its combination with trastuzumab in patients with HER2-positive disease. This trial may provide clinical evidence for the approach presented here.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-12-03.

Abstract P3-06-18: Increase of serum androgen and its metabolites in postmenopausal primary breast cancer patients with disease progression during neo-adjuvant exemestane treatment; JFMC 34–0601 TR

BACKGROUND: We reported a positive correlation between body mass index (BMI) and clinical response to neo-adjuvant hormonal therapy (NAH) with steroidal aromatase inhibitor, exemestane, in post-menopausal breast cancer patients (Takada M et al. Breast 2012). Here, we examined the relationship between serum concentrations of sex steroids and BMI, and explored their predictive value for clinical response.

PATIENTS AND METHODS: Among the 116 post-menopausal patients enrolled in the JFMC 34–0601 clinical trial of 24 weeks (wks) of NAH with exemestane, serums from 60 patients at pre-treatment, at 4wks and end of the treatment (24wks) were subjected to this study. Estradiol (E2), estrone (E1), dehydroepiandrosterone (DHEA), androstenedione (A-dione), 5-androstene-3β, 17β-diol (Aenediol), 5α-androstane-3β, 17β-diol (Aanediol) were measured using LC-MS/MS analysis and E1- sulfate (E1S) was by RIA.

RESULTS: There were no significant correlations between pre-treatment concentrations of sex steroids and BMI, except for moderate correlation of E2 and BMI (p = 0.004). In multivariate analysis, E1 was an independent predictive factor for objective response [odds 6.0, 95% confidence interval (CI) 1.5 — 34.6, p = 0.011], as well as BMI. All of the estrogens decreased to under-detection levels (0.5 for E1 and E2, 5 pg/assay for E1S) at 4 wks of treatment, and maintained through to the end of treatment in almost all patients independently of clinical response. The geometric mean percentage changes in androgens after NAH were: DHEA −0.2% (95%CI −15.3% — +17.6%) for patients without progressive disease (non-PD) and +44.8% (95%CI +22.1% — +71.8%) for patients with progressive disease (PD); A-dione −2.3% (95%CI −17.3% — +15.4%) for non-PD and +45.6% (95%CI +28.3% — +65.3%) for PD; Aenediol −11.5% (95%CI −20.6% — −1.4%) for non-PD and +24.9% (95%CI +1.9% — +53.0%) for PD; Aanediol +21.3% (95%CI −5.5% — +55.8%) for non-PD and +56.3% (95%CI +5.3% — +132.0%) for PD, respectively. The changes in the concentrations of both DHEA and A-dione in patients with PD were statistically significant (p = 0.008 and p = 0.002, respectively). In all of the PD patients, the serum concentrations of DHEA and A-dione were increased after NAH.

CONCLUSION: Pretreatment serum concentration of E1 was an independent predictive factor for clinical response to NAH with exemestane. Measurement of dynamics of the serum androgen concentrations might be helpful for monitoring treatment response, and mechanism of increase of androgens has a value for further investigation. Our results should be validated using a larger dataset. (UMIN ID; C000000345)

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-06-18.

Abstract P1-14-02: Preoperative docetaxel (T) with or without capecitabine (X) following epirubicin, 5-fluorouracil and cyclophosphamide (FEC) in patients with operable breast cancer (OOTR N003): Results of comparative study and predictive marker analysis

Objective: This preoperative study aimed to evaluate the efficacy of 4 cycles of TX compared with 4 cycles of T, following 4 cycles of FEC in operable breast cancer patients.

Methods: Women with operable breast cancer (T1C-3N0M0/T1-3N1M0) were randomly assigned to receive either T (75 mg/m2, q3) plus X (825 mg/m2 bid, days 1 to 14) or T alone (75 mg/m2, q3) after completion of FEC (5-fluorouracil 500 mg/m2, epirubicin 100 mg/m2, cyclophosphamide 500 mg/m2, q3). Patients who had disease progression on FEC were excluded from randomization. The primary endpoint was pathological complete response (pCR). Predictive factor analysis was conducted using clinicopathological markers such as hormone receptors, Ki67 labeling index (Ki67LI) and thymidine phosphorylase (TP).

Results: From November 2005 to October 2009, 504 patients were enrolled and 239 and 238 patients were assigned to TX and T group, respectively (median age 49 years, median tumor size 3.5 cm and node positive rate 56%). Treatment discontinuation was observed in 22% of TX group and 5% in T group (p < 0.0001). The major reasons for discontinuation were toxicity, refusal/ consent withdrawal and several others. No significant difference in pCR rate was shown between the two groups (TX 23% and T 24%, p = 0.748). Neither clinical response nor surgical outcome differed between TX and T. The pCR rate in patients who had therapy discontinuation or dose-reduction on TX was 23%, whereas pCR rate in those on T was 11%. A subpopulation treatment effect pattern plots method indicated a trend that TX may improve the pCR rate in patients having a middle range of pretreatment Ki67LI, such as 10%–20%. In the median follow-up time of 3.7 years, disease-free survival (DFS) was not different between TX and T (3-year DFS: 92% in TX and 91% in T; hazard ratio 0.907, 95%CI 0.528–1.557, p = 0.723). The frequency of major grade 3 or greater adverse events of TX and T were leukopenia, 36% and 34%, febrile neutropenia 8% and 5%, and hand-foot syndrome 15% and 2%, respectively.

According to the analysis for evaluating predictive values of biomarkers, a multivariate logistic regression analysis showed that HER2 (+/−: odds ratio 4.107, p < 0.0001), Ki67LI (continuous variables: 1.029, p = 0.003), hormone receptor status (+/−: 0.457, p = 0.009), stroma TP status (0.523, p = 0.02) and grade (1/3: 0.387, 2/3: 0.532, p = 0.047) had statistical significant values for predicting pCR. A multiple Cox model in landmark analysis showed that tumor size (p < 0.0001), cancer cell TP status (p = 0.005), pCR and posttreatment Ki67LI (p = 0.016), and age (p = 0.049) were associated with DFS significantly.

Conclusions: Addition of X to T showed no superiority to T alone following FEC in neoadjuvant treatment of these patients with operable breast cancer. Treatment discontinuation rate was significantly higher in TX than T group, however the pCR rate in patients in TX group who required treatment discontinuation or dose-reduction was similar to that in patients who completed as scheduled, which was different from T group. Determination of pre-/ post-treatment Ki67LI looks useful for predicting pCR and DFS.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-14-02.

Abstract P4-12-06: A mammographic density prediction model using environmental factors, endogenous hormones and growth factors in Japanese women

The incidence of breast cancer in Japanese women has doubled in all age groups over the past two decades, making it important to evaluate breast cancer risk factors in Japanese women. It is well known that mammographic density is positively associated with breast cancer risk in Western countries, and mammographic density is known to be affected by some environmental factors, serum hormones, and growth factors. We performed stepwise variable selection in a multiple regression model with fifteen independent variables as described below, based on the Akaike information criteria (AIC) to build a mammographic density prediction model using a dataset of 1191 women (913 women with breast cancer and 278 disease-free controls). The variables included were: environmental risk factors (body-mass index (BMI), age at menarche, pregnancy, age at first birth, breastfeeding, family history of breast cancer, age at menopause, use of hormone replacement therapy, alcohol intake and smoking), serum hormones and growth factors (estradiol, testosterone, prolactin, insulin-like growth factor 1 (IGF1) and IGF binding protein 3 (IGFBP3)) and mammographic density. The resulting prediction model is:

Mammographic density = + 0.000476 (IGF1) −0.0605 (testosterone) − 0.0508 (IGFBP3) − 0.00683 (age) − 0.0175 (BMI) + 0.00883 (age at menarche) − 0.0153 (breast feeding), (R2 = 0.336).

In this model, IGF1, testosterone, IGFBP3, age, BMI, age at menarche, and breastfeeding were considered to be important factors. IGF1 and age at menarche were positively associated with mammographic density, while on the other hand testosterone, IGFBP3, age, BMI, and breast feeding were negatively associated with mammographic density. Further studies are required to build a modified model incorporating serial measurements of serum hormones and growth factors to take into account time-dependent changes of serum hormones and growth factors, and to assess its accuracy.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-12-06.

SU-E-J-203: Determination of PTV Margin for Lung Tumor Using In-Treatment 4D CBCT

PURPOSE

To determine a planning target volume (PTV) margin for lung cancer patients using a four-dimensional cone-beam CT (4D CBCT) acquired during volumetric modulated arc therapy (VMAT) treatment.

METHODS

A VMAT plan for lung cancer patients was created by Pinnacle v9.0 (Philips) treatment planning system (TPS), where the gross target volume (GTVs) in each breathing phase was delineated by using 4D-planning CT scan (TOSHIBA and ANZAI). The VMAT treatment was performed with a stereotactic body frame after the registration using Elekta X-ray volume imaging (XVI) unit. Simultaneous cone-beam projection images were acquired for 3 or 4 fractions of 10 patients. The in-treatment 4D CBCT was reconstructed by dividing into four breathing phase bins. A total of 38 in-treatment 4D-CBCT sets were exported to Pinnacle TPS. The isocenter of in-treatment 4D CBCT was matched with that of 4D-planning CT. The tumor motion during treatment was manually tracked on in-treatment 4D CBCT, and the center-of-mass (COM) location of the tumor was estimated. Analyzing the tumor regions observed by in-treatment 4D CBCT, a PTV margin in our system was derived.

RESULTS

The average difference in COM location of the tumor was less than 1mm for all directions, while the standard deviations (SD's) were about 1.3mm, 1.6mm, and 2.1mm for the lateral, the vertical, and the longitudinal directions, respectively. The large discrepancy more than 3mm was observed for one patient. The required PTV margin was about 3-4mm for the lateral and the vertical directions, whereas it was about 5mm for the longitudinal direction.

CONCLUSIONS

The uncertainties of the tumor motion caused by respiration were observed by in-treatment 4D CBCT images. It was feasible to determine the PTV margin from 4D volume images. K. Nakagawa receives research funding from Elekta.