Stereotactic radiation treatment planning with volumetric modulated arc therapy: Impact of duodenal sparing on pancreatic tumor coverage

301

Background: Volumetric modulated arc therapy (VMAT) allows for intensity-modulated radiation delivery with faster treatment times and fewer delivered monitor units (MU). The dose-limiting structure for pancreatic stereotactic body radiation therapy (SBRT) is the duodenum. We evaluate VMAT dose distribution, delivery times, and the effect of duodenal sparing (DS) for pancreas SBRT.

Methods: Plans of 15 patients with unresectable pancreatic cancer (14 head/1 tail) were selected. VMAT treatment planning with the “SmartArc” function of Pinnacle v. 8.9 was used to plan one fraction of 25 Gy to the PTV (gross tumor + 2 mm expansion) normalized to the 80% isodose line. Two VMAT SBRT plans were conducted for each case; the first did not attempt to spare the duodenum (non DS) while the second did (DS). Constraints were stomach/duodenum any point max <30 Gy (for DS plan), liver D50 < 5 Gy, ipsilateral kidney D25 < 5 Gy, cord Dmax < 5 Gy and stomach D4 < 22.5 Gy.

Results: Gross tumor volume ranged from 58.4cm3 to 320.3 cm3. The average overlap volume between PTV and the duodenum was 8.4 cm3. In 10/15 non-DS plans, the duodenal Dmax exceeded 30 Gy. With DS optimization, only 1/15 plans exceeded the 30 Gy threshold. These differences were statistically significant (p<0.001). Typical MU and delivery times, as calculated by the planning software, were 5494 MU and 775 secs vs. 5296 MU and 703 secs for the DS and non-DS plans, respectively. The difference in delivery times was significant (p=0.01), but amounted to only 1.2 min on average. The average duodenal Dmax for non-DS plans was 30.4Gy, D4% was 23.4 Gy. With DS, the average Dmax was reduced to 28.1Gy and D4% to <19.7 Gy (p<0.001). As expected, VMAT plans with greater overlap between the duodenum and PTV had a higher duodenal Dmax.

Conclusions: This study demonstrates the feasibility of VMAT for high-dose SBRT treatment of pancreatic cancer incorporating constraints to limit the dose to the duodenum. Future studies will evaluate whether VMAT with fractionated SBRT results in improved duodenal sparing more efficiently than traditional IMRT.

No significant financial relationships to disclose.

Abstract P4-08-05: Delineation of HER2 Gene Status in Korean Breast Cancers by Standardized Immunohistochemistry (IHC) and Silver In Situ Hybridization (SISH): Comparison of Local IHC Result with Central IHC and SISH Results

Background: Amplification of the human epidermal growth factor receptor 2 (HER2) gene and concomitant protein overexpression are present in 20-25% of breast cancers. HER2 overexpression and/or gene amplification is associated with a worse clinical outcome and an important predictive marker for sensitivity to anthracycline-based chemotherapy and HER2- targeted therapy. In Korea, the HER2 status has usually been assessed by immunohistochemistry (IHC) in the laboratories. To verify the preanalytic, analytic, and postanalytic factors of IHC in multi-institutions, we assessed the interlaboratory variability of HER2 IHC by comparing the local IHC with the central IHC and SISH results, as a first step toward building a nationwide quality assurance program.

Methods: The Breast Pathology Study Group of Korean Society of Pathologists collected 1,198 breast carcinoma samples from 7 university-based hospitals and constructed 56 tissue microarray (TMA) blocks with triplicate of 1 mm cores. Local IHC results for HER2 were obtained from 1,130 patients. We performed IHC (PATHWAY anti-HER2/neu (4B5) rabbit monoclonal antibody, Ventana Medical Systems) and SISH (INFORM HER2 DNA Probe Kit, Ventana Medical Systems) for HER2 on the TMA sections using the automated Benchmark platform (Ventana Medical Systems). We interpreted the results according to the American Society of Clinical Oncology/College of American Pathologists guidelines. Results from local IHC were compared with central IHC and SISH. The concordant rates between central IHC and SISH results were also calculated.

Results: The total percentage of cases in each category of local IHC score was: 0/1+, 70.4%; 2+, 8.8% (range among hospitals, 0-36%); and 3+, 20.8% (10.8-28.8%). The percentage of central IHC results (1,110 patients) in each category was: 0/1+, 79.7%; 2+, 3.6% (1.1-8.3%); and 3+, 16.7% (13.1-18.8%). SISH results were obtained from 1,033 patients: negative, 79.5%; equivocal, 0.2% (0-1.6%); and positive, 20.3% (19.2-22.6%). SISH amplifications in each local IHC category were observed as follows: 0/1+, 4.3% (0.6-10%); 2+, 18.8% (5.6-66.7%); and 3+, 71.2% (50-97.3%). When considering the central SISH as gold standard, 3% of cases (30/995) were false negative and 6.3% (63/995) were false positive in local IHC. In central lab, the concordance rates between IHC 3+ and SISH-positive, and IHC 0/1+ and SISH-negative were 95.5% and 98%, respectively.

Conclusions: The results of central IHC and SISH markedly decreased the interlaboratory variability of HER2 status. The measurement of HER2 gene amplification by SISH was less affected by the preanalytic factors than the measurement of overexpression of HER2 protein by IHC. Because the rate of false positivity is higher than that of false negativity in the local IHC, the quality assurance program needs to be focused on decreasing not only the false negativity, but also the false positivity of HER2 IHC in local laboratories

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-08-05.

Lysophosphatidic acid augments human hepatocellular carcinoma cell invasion through LPA1 receptor and MMP-9 expression

Lysophosphatidic acid (LPA), produced extracellularly by autotaxin (ATX), has diverse biological activities implicated in tumor initiation and progression, including increasing cell survival, angiogenesis, invasion and metastasis. ATX, LPA and the matrix metalloproteinase (MMP)-9 have all been implicated in hepatocellular carcinoma (HCC) invasion and metastasis. We, thus sought to determine whether ATX with subsequent LPA production and action, including induction of MMP-9 could provide a unifying mechanism. ATX transcripts and LPA receptor type 1 (LPA1) protein are elevated in HCC compared with normal tissues. Silencing or pharmacological inhibition of LPA1 significantly attenuated LPA-induced MMP-9 expression and HCC cell invasion. Further, reducing MMP-9 activity or expression significantly inhibits LPA-induced HCC cell invasion, demonstrating that MMP-9 is downstream of LPA1. Inhibition of phosphoinositide-3 kinase (PI3K) signaling or dominant-negative mutants of protein kinase Cδ and p38 mitogen-activated protein kinase (MAPK) abrogated LPA-induced MMP-9 expression and subsequent invasion. We thus demonstrate a mechanistic cascade of ATX-producing LPA with LPA activating LPA1 and inducing MMP-9 through coordinate activation of the PI3K and the p38 MPAK signaling cascades, providing novel biomarkers and potential therapeutic targets for HCC.

Ferromagnetically coupled Shastry-Sutherland quantum spin singlets in (CuCl)LaNb₂O₇

A thorough crystal structure determination at very low temperature of (CuCl)LaNb₂O₇, originally proposed as a spin-1/2 square-lattice antiferromagnet, is reported thanks to the use of single-crystal x-ray diffraction and powder neutron diffraction. State-of-the-art calculations (maximum entropy method) reveal that (CuCl)LaNb₂O₇ is orthorhombic with Pbam symmetry. First-principles calculations demonstrate that the dominant magnetic interactions are antiferromagnetic between fourth nearest neighbors with a Cu-Cl-Cl-Cu exchange path, which lead to the formation of spin singlets. The two strongest interactions between the singlets are ferromagnetic, which makes (CuCl)LaNb₂O₇ the first system of ferromagnetically coupled Shastry-Sutherland quantum spin singlets.

Dexamethasone synergizes with lenalidomide to inhibit multiple myeloma tumor growth, but reduces lenalidomide-induced immunomodulation of T and NK cell function

To determine the effect of dexamethasone on the antimyeloma effects of lenalidomide, we tested in vitro proliferation, tumor suppressor gene expression, caspase activity, cell cycling, and apoptosis levels in a series of multiple myeloma (MM) and plasma cell leukemia cell lines treated with lenalidomide and dexamethasone, alone or in combination. The effect of dexamethasone on the immunomodulatory activities of lenalidomide such as T cell and natural killer (NK) cell activation was measured via interleukin [IL]-2 production, and interferon-gamma and granzyme B production respectively. Lenalidomide inhibited proliferation in most cell lines tested, and this effect was enhanced by dexamethasone. This effect was observed in MM cells containing the high-risk cytogenetic abnormalities t(4;14), t(14;16), del17p, del13, and hypodiploidy. Mechanistically, lenalidomide plus dexamethasone synergistically induced expression of the tumor suppressor genes Egr1, Egr2, Egr3, p15, p21, and p27 in MM cell lines and MM patient cells. The combination activated caspases 3, 8, and 9; and induced cell cycle arrest and apoptosis. Lenalidomide alone increased T cell production of IL-2, and NK cell production of interferon-gamma and granzyme B. Notably, dexamethasone antagonized these immunostimulatory effects of lenalidomide in a dose-dependent manner. These data further elucidate the mechanism of action of lenalidomide and dexamethasone in MM, and suggest that use of low-dose dexamethasone with lenalidomide may retain the antiproliferative effect of lenalidomide while permitting greater immunomodulatory effects of this combination regimen.

Sulforhodamine 101 induces long-term potentiation of intrinsic excitability and synaptic efficacy in hippocampal CA1 pyramidal neurons

Sulforhodamine 101 (SR101) has been extensively used for investigation as a specific marker for astroglia in vivo and activity-dependent dye for monitoring regulated exocytosis. Here, we report that SR101 has bioactive effects on neuronal activity. Perfusion of slices with SR101 (1 microM) for 10 min induced long-term potentiation of intrinsic neuronal excitability (LTP-IE) and a long-lasting increase in evoked EPSCs (eEPSCs) in CA1 pyramidal neurons in hippocampal slices. The increase in intrinsic neuronal excitability was a result of negative shifts in the action potential (AP) threshold. The N-methyl D-aspartate receptor (NMDAR) antagonist, AP-5 (50 microM), blocked SR101-induced LTP-IE, but glutamate receptor blockers, AP-5 (50 microM), MCPG (200 microM), and MSOP (100 microM), only partially blocked SR101-induced potentiation of eEPSCs. SR101 induced an enhancement of evoked synaptic NMDAR currents, suggesting that SR101 enhances activation of synaptic NMDARs. SR101-induced LTP-IE and potentiation of synaptic transmission triggered spontaneous neuronal firing in slices and in vivo epileptic seizures. Our results suggest that SR101 is an epileptogenic agent that long-lastingly lowers the AP threshold to increase intrinsic neuronal excitability and enhances the synaptic efficacy to increase synaptic inputs. As such, SR101 can be used as an experimental tool to induce epileptic seizures.

Longitudinal assessment of fibrinogen in relation to subclinical cardiovascular disease: the CARDIA study

OBJECTIVE

To examine the strength of the associations of fibrinogen with subclinical atherosclerosis in healthy persons.

METHODS

A population-based, prospective, observational study of black and white men and women (Coronary Artery Risk Development in Young Adults [CARDIA]). Fibrinogen levels were measured at year 7 (ages 25-37, n = 2969), and again at year 20 (ages 38-50, n = 2832). Measures of subclinical atherosclerosis (coronary artery calcification [CAC] and carotid intimal-medial thickness [CIMT]) were recorded at year 20.

RESULTS

Over the 13-year study interval (1992-1993 to 2005-2006), fibrinogen rose from a mean of 3.32 to 4.05 g L(-1). After adjusting for age, gender and race, fibrinogen was positively associated with greater incidence of CAC and increased CIMT cross-sectionally as well as after 13 years of follow-up (all P-trend < 0.001). After further adjustment for field center, BMI, smoking, education, systolic blood pressure, diabetes, antihypertensive medication use, total and HDL cholesterol, and CRP, significant positive relationships between fibrinogen and incidence of CAC remained for the total cohort longitudinally (P-trend = 0.037), but not cross-sectionally (P-trend = 0.147).

CONCLUSION

This 13-year study demonstrates that higher levels of fibrinogen during young adulthood are positively associated with incidence of CAC and increased CIMT in middle-age, but the strength of the association declines with increasing age.

SpermCheck Fertility, an immunodiagnostic home test that detects normozoospermia and severe oligozoospermia

BACKGROUND

A simple and inexpensive home sperm test could be of considerable value to couples attempting to conceive and to men curious about their fertility potential. A two-strip lateral flow immunochromatographic diagnostic device that allows men to evaluate their sperm count at low cost in the privacy of their own homes is described.

METHODS

The ability of SpermCheck Fertility to predict sperm counts obtained using a hemacytometer procedure based on standard World Health Organization methodology was assessed. Test results obtained by lay users were also compared with those obtained by trained laboratory professionals, and the ease of use of the device was evaluated in consumer studies.

RESULTS

A total of 225 semen samples were analyzed in the method comparison, and the performance of SpermCheck Fertility was excellent with over 96% of all samples correctly classified as normozoospermic (> or =2 x 10(7) sperm/ml), oligozoospermic (5 x 10(6)-2 x 10(7) sperm/ml) or severely oligozoospermic (<5 x 10(6) sperm/ml). Consumer studies with 164 lay users demonstrated that SpermCheck Fertility was easy to use. Lay users and laboratory professionals agreed 95% of the time when reading the same test independently. Overall, the correct response rate on a 20-question survey about the test was over 97%.

CONCLUSIONS

SpermCheck Fertility is a simple and reliable immunodiagnostic test that can quickly inform men as to whether their sperm count is normal, low or very low. This home test can assist couples in deciding whether to seek comprehensive clinical evaluation of the fertility status of the male partner.

A Phase 1 Study To Assess the Safety, Tolerability and Pharmacokinetics of ARRY-380 – An Oral Inhibitor of HER2

Background: ARRY-380 is a potent, orally active small molecule that selectively inhibits HER2 signaling in vitro and in vivo and significantly inhibits tumor growth in a variety of HER2-dependent tumor xenograft models. Based on its preclinical activity, tolerability and pharmacokinetic (PK) profile, a Phase 1 study was initiated to evaluate the safety, tolerability and PK profile of ARRY-380 as a single agent in patients with solid tumors and to establish the maximum tolerated dose (MTD).Methods: Patients with HER2 positive breast cancer or other tumor types for which published evidence of HER2 expression exists were treated with ARRY-380 as a single oral dose on Cycle 1 Day 1, followed by continuous twice-daily (BID) oral dosing starting on Cycle 1 Day 3. ARRY-380 was escalated in cohorts of 3 to 4 patients, using standard dose-limiting toxicity (DLT) criteria during Cycle 1 to determine dose escalation. Serial PK assessments were made during Cycle 1 on Days 1, 2, 3 and at steady-state on Day 15.Preliminary Results: As of June 1, 2009, 15 patients have been treated in 5 dosing cohorts at doses of 25 to 300 mg BID. Patients had a median age of 61 years (range, 37-77 years) and ECOG PS of 0 to 2. Cancer types included HER2+ breast cancer (8), colorectal (6) and salivary gland (1). No DLTs have been observed and drug-related adverse events have included Grade 1 nausea, rash and fatigue and Grade 2 fatigue in 2 patients at the 200 mg BID dose level. Preliminary PK analyses indicate a trend for increasing Cmax and AUC with increasing dose, a median Tmax of 2 hours and a mean t1/2 of 4.6 hours across all cohorts. Two patients with HER2+ breast cancer have had stable disease for ≥ 4 months with no significant toxicity. One of these two patients had a notable reduction in liver metastases (28%) after 2 cycles of ARRY-380 and is currently on study.Conclusions: ARRY-380 has demonstrated an acceptable safety and PK profile and preliminary signs of clinical benefit. Dose escalation continues to determine the MTD.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 5111.

Magnetoelastic coupling through the antiferromagnet-to-ferromagnet transition of quasi-two-dimensional [Cu(HF2)(pyz)2]BF4 using infrared spectroscopy

We investigated magnetoelastic coupling through the field-driven transition to the fully polarized magnetic state in quasi-two-dimensional [Cu(HF2)(pyz)2]BF4 by magnetoinfrared spectroscopy. This transition modifies out-of-plane ring distortion and bending vibrational modes of the pyrazine ligand. The extent of these distortions increases with the field, systematically tracking the low-temperature magnetization. These distortions weaken the antiferromagnetic spin exchange, a finding that provides important insight into magnetic transitions in other copper halides.

Consequences of the intrachain dimer-monomer spin frustration and the interchain dimer-monomer spin exchange in the diamond-chain compound azurite Cu(3)(CO(3))(2)(OH)(2)

The spin lattice appropriate for azurite Cu(3)(CO(3))(2)(OH)(2) was determined by evaluating its spin exchange interactions on the basis of first principles density functional calculations. It is found that azurite is not well described as an isolated diamond chain with no spin frustration, but is better modeled as a two-dimensional spin lattice in which diamond chains with spin frustration interact through the interchain spin exchange in the ab-plane. Our analysis indicates that the magnetic properties of azurite at low temperatures can be approximated on the basis of two independent contributions, i.e., isolated dimer and effective uniform chain contributions. This prediction was verified by analyzing the magnetic susceptibility and specific heat data for azurite.