Abstract 2879: Pre-clinical characterization of Dacomitinib, an irreversible pan-HER inhibitor, combined with radiation therapy in head and neck cancer models

Introduction: Head and neck cancer is the 5th most common cancer worldwide; the majority of cases (>90%) are squamous cell carcinomas (SCCHNs). Despite advances in treatment, the 5-year overall survival rate for SCCHN patients still remains at ∼40-50%, underscoring the need to develop novel therapeutic strategies. EGFR is over-expressed in ∼90% of SCCHN cases, and is associated with tumor progression and poor prognosis. Dacomitinib (D), an irreversible pan-HER inhibitor, has demonstrated clinical potential in patients with non-small cell lung cancer, leading us to explore its therapeutic efficacy in SCCHN pre-clinical models, in combination with radiation therapy (RT), a curative modality for HNC management. Methods: The basal expression of EGFR family members was assessed via qRT-PCR in three SCCHN models (FaDu (human hypopharyngeal), UTSCC-8 & -42a (both laryngeal) squamous cancer, and NOE (normal oral epithelial) cell lines. MTS-based cell viability and clonogenic assays were performed with various concentrations of D, both alone and in combination with irradiation (IR). Inhibition of EGFR signalling by D was confirmed via immunoblotting. Cell cycle analysis was performed to assess mode of cytotoxicity. In vivo therapeutic studies were performed using FaDu xenografts in SCID mice; tumors were extracted post-treatment and examined for TUNEL, CD31, Ki67, and pEGFR via IHC. Results: EGFR was over-expressed in all three SCCHN, compared to the NOE cells. PF (50 nM) reduced FaDu cell viability by ∼25%, with an additive interaction being observed when D was combined with 2 Gy IR (∼36%). Similar trends were observed in the other two cell lines and also in the clonogenic assays. Immunoblotting confirmed a dose-dependent inhibition of EGFR signalling in D-treated SCCHN cells, along with downstream reduction of p-Erk, p-Akt, and p-mTOR expression. Cell cycle analyses showed ∼20% increase in the G0/G1 cell population in D-treated FaDu cells, and ∼10% increase in the sub-G cell population when D and IR were combined. Mice treated with the combination of D + IR exhibited a maximum tumor growth delay of ∼21 days, as compared to the IR only group, determined by time to tumor-plus-leg diameter of 14mm. Preliminary histological analysis of the extracted tumor tissue show ∼40% reduction in Ki67 staining in the PF + IR treated mice. The addition of D to IR appeared to be well-tolerated, with no change in body weight, or extent of alopecia. Conclusion: Dacomitinib effectively inhibited EGFR signalling in SCCHN models, leading to a reduction in cell viability and clonogenic survival in vitro, along with tumor growth delay in vivo. When D was combined with IR, there was an additive interaction, both in vitro and in vivo. Thus, D combined with RT may have a therapeutic benefit for patients with SCCHN.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2879. doi:1538-7445.AM2012-2879

Regulation in the targeting of TRAIL receptor 1 to cell surface via GODZ for TRAIL sensitivity in tumor cells

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and its receptors, TRAIL-R1 (DR4) and TRAIL-R2 (DR5), promote the selective clearing of various malignancies by inducing apoptosis, holding the promise as a potent therapeutic agent for anticancer. Though DR4 and DR5 have high sequence similarity, differential regulation of both receptors in human tumor cells remains largely unexplored. Here, we repot that golgi-specific Asp-His-His-Cys (DHHC) zinc finger protein (GODZ) regulates TRAIL/DR4-mediated apoptosis. Using the SOS protein recruitment-yeast two-hybrid screening, we isolated GODZ that interacted with the death domain of DR4. GODZ binds to DR4, but not to DR5, through the DHHC and the C-terminal transmembrane domain. Expression level of GODZ affects apoptosis of tumor cells triggered by TRAIL, but not that induced by TNF-α/cycloheximide (CHX) or DNA-damaging drugs. In parallel, GODZ functions to localize DR4 to the plasma membrane (PM) via DHHC motif. Also, introduction of mutation into the cysteine-rich motif of DR4 results in its mistargeting and attenuates TRAIL- or GODZ-mediated apoptosis. Interestingly, GODZ expression is highly downregulated in Hep-3B tumor cells, which show resistance to TRAIL. However, reconstitution of GODZ expression enhances the targeting of DR4 to cell surface and sensitizes Hep-3B cells to TRAIL. Taken together, these data establish that GODZ is a novel DR4-selective regulator responsible for targeting of DR4 to the PM, and thereby for TRAIL-induced apoptosis.

Iris Nertschinskia ethanol extract differentially induces cytotoxicity in human breast cancer cells depending on AKT1/2 activity

Recently, we reported that an ethanol extract of Iris nertschinskia induces p53-dependent apoptosis in the MCF7 human breast cancer cell line. However, the detailed mechanisms were not fully explored. Here, we demonstrate another aspect of the activity of I. nertschinskia in breast cancer cells. We compared the response to an ethanol extract of I. nertschinskia in two different human breast cancer cell lines, Hs578Tand MDA-MB231, respectively with relatively low and high AKT1/2 activity by trypan blue exclusion assay and FACS analysis. Knockdown of endogenous AKT1 or AKT2 in breast cancer cells by RNA interference determined the sensitivity to I. nertschinskia ethanol extract compared to control cells. The I. nertschinskia ethanol extract induced cell death in a manner that depended on the level of phosphorylated AKT1/2 protein and was associated with a significant increase in the sub-G1 cell population, indicative of apoptosis. Our results indicate that an ethanol extract of I. nertschinskia differentially induces cell death in breast cancer cells depending on their level of phosphorylated AKT1/2.

P4-11-20: Observational Study of Body Weight Changes and Metabolic Syndrome in Breast Cancer Patients Receiving Adjuvant Therapy: Characteristics of Dietary Pattern in Korean Breast Cancer Patients

Backgroud: Obesity, postdiagnosis weight gain, and presence of metabolic syndrome in breast cancer are reported to adversely affect survival among breast cancer survivors. Most of the studies on weight gain and metabolic syndrome in breast cancer are from Western countries and few information is available on Asian population. We designed this prospective observational study to characterize weight and metabolic changes during adjuvant treatment in women with early breast cancer and to identify factors associated with occurrence of metabolic syndrome, focusing on dietary pattern.

Methods: Patients aged 18–75 who underwent curative surgery with stage I-III invasive breast cancer were enrolled from 2008 to 2010. We measured glucose (FBS), hemoglobin A1c (HbA1c), total cholesterol (TC), HDL cholesterol, and triglyceride (TG) level in fasting serum samples before starting adjuvant therapy, at 6 months and 12 months after enrollment. Body weight, body mass index (BMI), body fat mass, and percent body fat at baseline, 6 months, and 12 months were also measured. Dietary intake was assessed using valid semi-quantitative Food frequency questionnaire (FFQ).

Results: Total of 63 patients were enrolled. Median age of the enrolled patients were 48 (range, 25–68), with premenopausal/postmenopausal 40 (63.5%)/ 23 (36.5%). Fifty (82.0%) and 10 (16.4%) received adjuvant chemotherapy followed by hormone therapy and hormone therapy alone. Hormone receptor positive (ER+/PR+) and HER2 positive cancer accounted for 52 (83.9%) and 7 (12.1%). Mean FBS, HbA1c, TC, HDL, and TG level was 99.9 mg/dL (range, 83–159), 5.59 mg/dL (range, 4.8−7.5), 197.4 mg/dL (125-298), 51.9 mg/dL (range, 30–90), and 119.7 mg/dL (42-371). Mean height, weight, and BMI was 158 cm (range, 149–169), 61.7kg (range, 46.2−96.0), and 24.7 kg/m2 (range, 18.7−35.7), respectively. According to the WHO and NTH guidelines for Asian, normal (BMI 18.5−22.9), overweight (BMI 23–24.9), and obesity (BMI≥25) was 18 (28.6%), 13 (20.6%), and 32 (50.8%), respectively. Number of patients with metabolic syndrome was 18 (34%). Mean BMI (26.1 vs 24.0, p=0.021) and TG (180.6 vs 92.0, p<0.001) was higher, HDL cholesterol was lower (42.2 vs 57.3, p<0.001) in patients with metabolic syndrome. Composition of daily calorie intake consisted of 13.5% (range 10.7−21.8) of protein, 6.7% (range, 3.3−22.1) of fat, and 70.1% (range, 28.1−79.5) of carbohydrate. The presence of metabolic syndrome was associated with a higher carbohydrate intake (carbohydrate intake per ideal body weight>6.0) (p=0.071). The TG level of patients who indigested high carbohydrate was significantly higher (143.8 vs 102.9, p=0.023). The HDL level of patients who took high fat diet (>20% of total calorie) was lower (45.3 vs 53.5, p=0.045).

Conclusion: In our cohort of Korean breast cancer patients, 34% had metabolic syndrome at baseline. Those patients with metabolic syndrome consumed higher proportion of carbohydrate, which resulted in significantly higher level of TG. Our data suggest that composition of calorie intake is different in Asian population compared to Western countries, warranting for reappraisal on the recommendation on life style modification and diet.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-11-20.

Uroporphyrinogen decarboxylase is a radiosensitizing target for head and neck cancer

Head and neck cancer (HNC) is the eighth most common malignancy worldwide, comprising a diverse group of cancers affecting the head and neck region. Despite advances in therapeutic options over the last few decades, treatment toxicities and overall clinical outcomes have remained disappointing, thereby underscoring a need to develop novel therapeutic approaches in HNC treatment. Uroporphyrinogen decarboxylase (UROD), a key regulator of heme biosynthesis, was identified from an RNA interference-based high-throughput screen as a tumor-selective radiosensitizing target for HNC. UROD knockdown plus radiation induced caspase-mediated apoptosis and cell cycle arrest in HNC cells in vitro and suppressed the in vivo tumor-forming capacity of HNC cells, as well as delayed the growth of established tumor xenografts in mice. This radiosensitization appeared to be mediated by alterations in iron homeostasis and increased production of reactive oxygen species, resulting in enhanced tumor oxidative stress. Moreover, UROD was significantly overexpressed in HNC patient biopsies. Lower preradiation UROD mRNA expression correlated with improved disease-free survival, suggesting that UROD could potentially be used to predict radiation response. UROD down-regulation also radiosensitized several different models of human cancer, as well as sensitized tumors to chemotherapeutic agents, including 5-fluorouracil, cisplatin, and paclitaxel. Thus, our study has revealed UROD as a potent tumor-selective sensitizer for both radiation and chemotherapy, with potential relevance to many human malignancies.