Abstract 1011: NNK promotes migration and invasion of cancer cells through activation of c-Src, PKCι and FAK loop

Cigarette smoking, either active or passive, is the most important risk factor in the development of human lung cancer. Mounting evidence indicates that cigarette smoke constituents not only contribute to tumorigenesis but also may increase the spread of cancer in the body. Nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is formed by nitrosation of nicotine and has been identified as the most potent carcinogen. NNK, an important component in cigarette smoke, may also promote tumor metastasis by regulating cell motility. Here we found that NNK can induce activation of a functionally interdependent protein kinase cascade, including c-Src, PKCι and FAK, in association with increased migration and invasion of human lung cancer cells. c-Src, PKCι and FAK are extensively co-localized in the cytoplasm. Treatment of cells with α7 nAChR specific inhibitor α-bungarotoxin (α-BTX) blocks NNK-stimulated activation of c-Src, PKCι and FAK and suppresses cell migration and invasion. Intriguingly, NNK enhances c-Src/PKCι and PKCι/FAK bindings, indicating a potential mechanism by which these kinases activate each other. Specific disruption of c-Src, PKCι or FAK expression by RNA interference significantly reduces NNK-induced cell migration and invasion. These findings suggest that NNK-induced migration and invasion may occur in a mechanism through activation of a c-Src/PKCι/ FAK loop, which can contribute to metastasis and/or development of human lung cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1011. doi:10.1158/1538-7445.AM2011-1011

Mono- or double-site phosphorylation distinctly regulates the proapoptotic function of Bax

Bax is the major multidomain proapoptotic molecule that is required for apoptosis. It has been reported that phosphorylation of Bax at serine(S) 163 or S184 activates or inactivates its proapoptotic function, respectively. To uncover the mechanism(s) by which phosphorylation regulates the proapoptotic function of Bax, a series of serine (S)→ alanine/glutamate (A/E) Bax mutants, including S163A, S184A, S163E, S184E, S163E/S184A (EA), S163A/S184E (AE), S163A/S184A (AA) and S163E/S184E (EE), were created to abrogate or mimic, respectively, either single or double-site phosphorylation. The compound Bax mutants (i.e. EA and AE) can flesh out the functional contribution of individual phosphorylation site(s). WT and each of these Bax mutants were overexpressed in Bax^−/− MEF or lung cancer H157 cells and the proapoptotic activities were compared. Intriguingly, expression of any of Bax mutants containing the mutation S→A at S184 (i.e. S184A, EA or AA) represents more potent proapoptotic activity as compared to WT Bax in association with increased 6A7 epitope conformational change, mitochondrial localization/insertion and prolonged half-life. In contrast, all Bax mutants containing the mutation S→E at S184 (i.e. S184E, AE or EE) have a mobility-shift and fail to insert into mitochondrial membranes with decreased protein stability and less apoptotic activity. Unexpectedly, mutation either S→A or S→E at S163 site does not significantly affect the proapoptotic activity of Bax. These findings indicate that S184 but not S163 is the major phosphorylation site for functional regulation of Bax's activity. Therefore, manipulation of the phosphorylation status of Bax at S184 may represent a novel strategy for cancer treatment.

Abstract 34: Oncogenic tyrosine kinases phosphorylate and inhibit PKM2 to provide a metabolic advantage to tumor growth

Cancer cells show increased aerobic glycolysis and enhanced lactate production compared to healthy cells, a phenomenon known as the Warburg effect. Cell surface growth factor receptors, which often carry tyrosine kinase activities in their cytoplasmic domains, are overexpressed in many human cancers and are believed to play a key role in determining cell metabolism. Thus, we explored the hypothesis that tyrosine kinase signaling, which is commonly increased in tumors, regulates the Warburg effect and contributes to tumorigenesis and maintenance of the tumor.

We performed phospho-proteomics studies and found that oncogenic forms of fibroblast growth factor (FGF) receptor type 1 (FGFR1) inhibit the pyruvate kinase M2 isoform (PKM2) in cancer cells. Pyruvate kinase is a rate-limiting enzyme during glycolysis and catalyzes the production of pyruvate and ATP from phosphoenolpyruvate (PEP) and ADP. Recent studies demonstrated that the enzymatic activity of the pyruvate kinase M2 isoform (PKM2) is inhibited by phosphotyrosine binding; moreover, these researchers found that PKM2 is crucial for aerobic glycolysis and provides a growth advantage to tumors. However, it remains unclear which tyrosine kinase pathways are physiologically responsible for this inhibition of PKM2 activity and which protein factors undergo tyrosine phosphorylation, allowing them to bind to and thereby inhibit PKM2. We found that PKM2 is itself tyrosine phosphorylated in cancer cells and such a physiological modification of PKM2 promotes the switch to aerobic glycolysis from oxidative phosphorylation. FGFR1 directly phosphorylates PKM2 at tyrosine residue 105 (Y105). This inhibits the formation of active, tetrameric PKM2 by disrupting binding of the PKM2 cofactor fructose-1,6-bisphosphate (FBP). Moreover, we found that phosphorylation of PKM2 Y105 is common in human cancers. Immunoblotting revealed that PKM2 is phosphorylated at Y105 in diverse human breast cancer, lung cancer, prostate cancer and leukemia cell lines. Oncogenic tyrosien kianses including BCR-ABL, FLT3-ITD and JAK2 also directly phosphorylate PKM2 Y105 in in vitro kinase assays using purified proteins. Furthermore, the presence of a PKM2 mutant in which phenylalanine is substituted for Y105 (Y105F) in cancer cells leads to decreased cell proliferation under hypoxic conditions, increased oxidative phosphorylation with reduced lactate production, and reduced tumor growth in xenografts in nude mice.

Our findings suggest that tyrosine phosphorylation regulates PKM2 to provide a metabolic advantage to tumor cells, thereby promoting tumor growth. This may represent a common, short-term molecular mechanism underlying the Warburg effect in both leukemias and solid tumors, in addition to the chronic changes believed to be regulated by transcription factors, including hypoxia inducible factor 1 and Myc.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 34.

Abstract 1201: Inhibition of ASK1 through phosphorylation of serine 967 by PI3K/Akt-mediated pathways

Cancer is characterized in part by dysregulation of cell survival and cell death signals. In particular, many tumors show upregulated PI3K/Akt activity, leading to sustained cell survival and suppressed cell death. Here we report the identification of the apoptosis signal-regulating kinase 1 (ASK1) as a downstream effector of the PI3K/Akt survival signaling pathway. ASK1 can be suppressed by PI3K/Akt signaling, leading to inhibition of apoptotic signaling. ASK1 normally functions as a mitogen activated protein kinase kinase kinase (MAP3K) that, when activated by stress signals, can evoke a signaling cascade leading to activation of the MAPKs JNK and p38. This activation can result in many cellular responses, but ASK1 is most notably known for its role as a critical regulator of apoptosis. Because of its crucial role in the balance between survival and death, ASK1 activity is tightly controlled. In particular, 14-3-3 can bind ASK1 and inhibit its activity when the kinase is phosphorylated at serine 967. However, the signals that regulate this phosphorylation event are currently unknown. Recent evidence suggests that PI3K/Akt mediated pathways may be involved in phosphorylation of serine 967 and, subsequently, inhibition of ASK1. Specifically, treatment of cells with growth factors including IGF-1 and PDGF increased phosphorylation of serine 967, as did overexpression of a constitutively active Akt mutant. In addition, expression of a kinase dead Akt mutant blocked growth factor induced serine 967 phosphorylation, indicating that Akt plays a role in mediating survival signals leading to inhibition of ASK1. In support of this notion, treatment with the inhibitors of Akt and PI3K also reduced serine 967 phosphorylation. Interestingly, treatment of cells with IGF-1 or overexpression of Akt was also able to protect serine 967 from H2O2 induced dephosphorylation. Taken together, our study reveals a novel effector site in ASK1 for the action of PI3K/Akt, which may offer a potential target for cancer therapeutic development. This work was supported by the NIH Pharmacological Sciences Training Grant T32 GM008602 and NIH/NCI Grant PO1CA116676 and USAMRMC05075002 to FRK and HF.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1201.

Proportion of subjects with an ethically acceptable reason for enrolling in a phase I trial

2512

Background: Concern persists that phase I subjects, who frequently enter trials for personal benefit, are deluded. They may suffer from therapeutic misconception (TM) - conflating research and clinical care, or from therapeutic misestimation (TMis) - misestimating benefits or risks. Methods: To estimate the proportion of phase I subjects who have an ethically acceptable reason for participation, we both interviewed and surveyed subjects to obtain qualitative and quantitative data. Ethically acceptable reasons included 1) Altruism (sole motive for entering trial was to help others or advance science); 2) Self-regarding motives but no TM (correctly identifying that the trial mostly intends to help research and gain knowledge, the study decides the treatments and the subjects get different doses of drug); 3) Self-regarding motives, TM but no TMis (chance of benefit < 20% and chance of risk > 0%); or 4) Self-regarding motives, TM, overestimation of benefits but broad view of benefit (with collateral benefits like getting careful disease monitoring or access to an academic center listed) and chance of risk > 0%. This generous interpretation of ethically acceptable reasons hinges on the view that subjects at least must recognize there is some risk, that chance of disease benefit is not high and that collateral benefits count. Results: The 86 subjects were mostly white, male, with incomes more than $60,000. 49% were college educated with a mean age of 60. 53.5% had an ethical reason for participation, with 10.5% altruistic, 16.3% no TM, 8.1% TM but no TMis, and 18.5% overestimating benefit but including collateral benefits. In both univariate and multivariate analyses age younger than 60 yo and having at least a college education were the only characteristics significantly correlated with having an ethically acceptable reason for participation. Those who reported strong religious beliefs (p = 0.01) were significantly more likely not to have an ethically acceptable reason. Conclusions: With almost half of participants lacking an ethically acceptable reason for participation, interventions are necessary to bolster understanding. Older participants lacking a college education are particularly at risk and could be the target for an intervention trial.

No significant financial relationships to disclose.

Efficacy and safety of PF-00299804 (PF299) in patients (pt) with advanced NSCLC after failure of at least one prior chemotherapy regimen and prior treatment with erlotinib (E): A two-arm, phase II trial

8063

Background: Options are limited for pts with NSCLC following chemotherapy and E. PF299 is an oral irreversible small molecule inhibitor of the HER-1,-2, and -4 tyrosine kinases. Based on non-clinical and phase I NSCLC data, this ongoing phase II U.S. trial evaluates PF299 in pts with NSCLC (KRAS wild-type) who have progressive disease after at least 1 prior chemotherapy regimen and after E. Methods: Pts were enrolled by histology: adenocarcinoma (Arm A) and non-adenocarcinoma (Arm B), and received PF299 45 mg QD. Endpoints include objective response rate, duration of response, progression-free survival, survival, safety/tolerability, and pharmacokinetics. Pharmacodynamic endpoints include assessment of serum levels of HER2 and EGFR extracellular domains. Tissue and blood KRAS assays, and EGFR studies on available tissue, are also being performed. Forty-four and 22 response-evaluable pts were planned to be enrolled into Arms A and B respectively. Results: Thirty-four pts with progressive NSCLC (25 female, 14 smoker) have enrolled to date (Arm A: 30; Arm B: 4): median duration of prior E: 11.5 months; median time since E: 2.5 months. Among 20 response-evaluable pts, stable disease (SD) was observed in 9/18 pts in Arm A, and 1/2 pts in Arm B: median duration of SD: 11.5 weeks [range 6+, 32+ weeks]. Observation of disease control included pts who had recently (≤8 weeks) discontinued E; and also pts whose tumor had known EGFR T790M mutations. At time of data cutoff, confirmation per RECIST of 2 partial responses is pending. The most common treatment-related AEs were skin and gastrointestinal disorders, with grade 3 AEs in 19% and 13% of pts, respectively. Two pts experienced grade 4 pulmonary embolus/dyspnea deemed possibly treatment-related, both in the setting of progressive disease. Conclusions: PF299 shows encouraging activity in NSCLC pts after failure of prior chemotherapy and E. The AE profile was predictable and consistent with the prior phase I trial. At submission, enrollment in the adenocarcinoma arm is complete and enrollment in the non-adenocarcinoma arm continues; updated efficacy data and tumor characterization will be presented.

[Table: see text]

Abstract B106: Inhibition of IKKb and NFκB signaling by a novel curcumin analogue

B106

The nuclear factor kappa-B (NF-κB) signaling pathway has been targeted for therapeutic applications in a variety of human diseases such as cancer. A number of naturally occurring substances including curcumin have been investigated for their actions on the NF-κB pathway because of their significant therapeutic potential and safety profile. A synthetic monoketone compound termed EF24 was developed from curcumin and exhibited a potent anticancer activity. Here we report a mechanism by which EF24 potently suppresses the NF-κB signaling pathway in both head and neck cancer and lung cancer cell lines through direct action on the I-κB kinase (IKK). We demonstrate that (i) EF24 induces death of lung, head and neck, breast, ovarian, and cervical cancer cells with a potency about 10 times higher than curcumin does, (ii) EF24 rapidly blocks the nuclear translocation of NF-κB with an IC50 of 1.3 μM compared with curcumin with an IC50 of 13 μM, (iii) EF24 effectively inhibits TNFα-induced I-κB phosphorylation and degradation, suggesting a role of this compound in targeting IKK, and (iv) EF24 indeed directly inhibits the catalytic activity of IKK in an in vitro reconstituted system. This study identifies IKK as an effective target for EF24 and provides a molecular explanation for a superior activity of EF24 over curcumin. The effective inhibition of TNFα-induced NF-κB signaling by EF24 extends the therapeutic application of EF24 to other NF-κB-dependent diseases, including inflammatory diseases such as rheumatoid arthritis.

Citation Information: Cancer Prev Res 2008;1(7 Suppl):B106.

Proliferative changes in the bronchial epithelium of former smokers treated with retinoids

BACKGROUND

Retinoids have shown antiproliferative and chemopreventive activity. We analyzed data from a randomized, placebo-controlled chemoprevention trial to determine whether a 3-month treatment with either 9-cis-retinoic acid (RA) or 13-cis-RA and alpha-tocopherol reduced Ki-67, a proliferation biomarker, in the bronchial epithelium.

METHODS

Former smokers (n = 225) were randomly assigned to receive 3 months of daily oral 9-cis-RA (100 mg), 13-cis-RA (1 mg/kg) and alpha-tocopherol (1200 IU), or placebo. Bronchoscopic biopsy specimens obtained before and after treatment were immunohistochemically assessed for changes in the Ki-67 proliferative index (i.e., percentage of cells with Ki-67-positive nuclear staining) in the basal and parabasal layers of the bronchial epithelium. Per-subject and per-biopsy site analyses were conducted. Multicovariable analyses, including a mixed-effects model and a generalized estimating equations model, were used to investigate the treatment effect (Ki-67 labeling index and percentage of bronchial epithelial biopsy sites with a Ki-67 index > or = 5%) with adjustment for multiple covariates, such as smoking history and metaplasia. Coefficient estimates and 95% confidence intervals (CIs) were obtained from the models. All statistical tests were two-sided.

RESULTS

In per-subject analyses, Ki-67 labeling in the basal layer was not changed by any treatment; the percentage of subjects with a high Ki-67 labeling in the parabasal layer dropped statistically significantly after treatment with 13-cis-RA and alpha-tocopherol treatment (P = .04) compared with placebo, but the drop was not statistically significant after 9-cis-RA treatment (P = .17). A similar effect was observed in the parabasal layer in a per-site analysis; the percentage of sites with high Ki-67 labeling dropped statistically significantly after 9-cis-RA treatment (coefficient estimate = -0.72, 95% CI = -1.24 to -0.20; P = .007) compared with placebo, and after 13-cis-RA and alpha-tocopherol treatment (coefficient estimate = -0.66, 95% CI = -1.15 to -0.17; P = .008).

CONCLUSIONS

In per-subject analyses, treatment with 13-cis-RA and alpha-tocopherol, compared with placebo, was statistically significantly associated with reduced bronchial epithelial cell proliferation; treatment with 9-cis-RA was not. In per-site analyses, statistically significant associations were obtained with both treatments.

Lipid rafts and nonrafts mediate tumor necrosis factor related apoptosis-inducing ligand induced apoptotic and nonapoptotic signals in non small cell lung carcinoma cells

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is capable of inducing apoptosis in non-small cell lung carcinoma (NSCLC). However, many of the human NSCLC cell lines are resistant to TRAIL, and TRAIL treatment of the resistant cells leads to the activation of nuclear factor-kappaB (NF-kappaB) and extracellular signal-regulated kinase 1/2 (ERK1/2). TRAIL can induce apoptosis in TRAIL-sensitive NSCLC cells through the induction of death-inducing signaling complex (DISC) assembly in lipid rafts of plasma membrane. In the DISC, caspase-8 is cleaved and initiates TRAIL-induced apoptosis. In contrast, TRAIL-DISC assembly in the nonraft phase of the plasma membrane leads to the inhibition of caspase-8 cleavage and NF-kappaB and ERK1/2 activation in TRAIL-resistant NSCLC cells. Receptor-interacting protein (RIP) and cellular Fas-associated death domain-like interleukin-1beta-converting enzyme-inhibitory protein (c-FLIP) mediates the DISC assembly in nonrafts and selective knockdown of either RIP or c-FLIP with interfering RNA redistributes the DISC from nonrafts to lipid rafts, thereby switching the DISC signals from NF-kappaB and ERK1/2 activation to caspase-8-initiated apoptosis. Chemotherapeutic agents inhibit c-FLIP expression, thereby enhancing the DISC assembly in lipid rafts for caspase-8-initiated apoptosis. These studies indicate that RIP and c-FLIP-mediated assembly of the DISC in nonrafts is a critical upstream event in TRAIL resistance and thus targeting of either RIP or c-FLIP may lead to the development of novel therapeutic strategies that can overcome TRAIL resistance in human NSCLC.

14-3-3 Integrates prosurvival signals mediated by the AKT and MAPK pathways in ZNF198-FGFR1-transformed hematopoietic cells

Human 8p11 stem cell leukemia/lymphoma syndrome usually presents as a myeloproliferative disorder (MPD) that evolves to acute myeloid leukemia and/or lymphoma. The syndrome associated with t(8;13)(p11;q12) results in expression of the ZNF198-FGFR1 fusion tyrosine kinase that plays a pathogenic role in hematopoietic transformation. We found that ZNF198-FGFR1 activated both the AKT and mitogen activated protein kinase (MAPK) prosurvival signaling pathways, resulting in elevated phosphorylation of the AKT target FOXO3a at T32 and BAD at S112, respectively. These phosphorylated residues subsequently sequestered the proapoptotic FOXO3a and BAD to 14-3-3 to prevent apoptosis. We used a peptide-based 14-3-3 competitive antagonist, R18, to disrupt 14-3-3-ligand association. Expression of R18 effectively induced apoptosis in hematopoietic Ba/F3 cells transformed by ZNF198-FGFR1 compared with control cells. Moreover, purified recombinant transactivator of transcription (TAT)-conjugated R18 proteins effectively transduced into human leukemia cells and induced significant apoptosis in KG-1a cells expressing FGFR1OP2-FGFR1 fusion tyrosine kinase but not in control HL-60 and Jurkat T cells. Surprisingly, R18 was only able to dissociate FOXO3a, but not BAD as previously proposed, from 14-3-3 binding and induced apoptosis partially through liberation and reactivation of FOXO3a. Our findings suggest that 14-3-3 integrates prosurvival signals in FGFR1 fusion-transformed hematopoietic cells. Disrupting 14-3-3-ligand association may represent an effective therapeutic strategy to treat 8p11 stem cell MPD.

Phase I/II Study of Docetaxel, Cisplatin, and Concomitant Boost Radiation for Locally Advanced Squamous Cell Cancer of the Head and Neck

Purpose

To investigate the feasibility of combining concomitant boost accelerated radiation with docetaxel and cisplatin and assess the regimen's toxicity, locoregional control rate, and survival in patients with locally advanced head and neck cancer (HNSCC).

Patients and Methods

Patients with stage III-IV HNSCC were eligible. Phase I included two schedules of docetaxel and cisplatin: arm 1, once per week during weeks 1 to 4; arm 2, every 21 days for weeks 1 and 4. Radiation consisted of 72 Gy in 42 fractions over 6 weeks (concomitant boost).

Results

Twenty patients were enrolled in phase I. The arm 1 maximum-tolerated dose (MTD) was defined at docetaxel 15 mg/m2 and cisplatin 20 mg/m2 based on prolonged mucositis in 29% of patients. The initial dose level in arm 2 was above the MTD. In total, 52 patients were treated using the arm 1 regimen in phase II. Acute toxicity included grade 3 mucositis and dermatitis in 81% and 44% of patients. The 2-year locoregional control rate was 71%. The 2-year progression-free and overall survival rates were 61% and 65%. Median survival was 37.8 months. Late effects included feeding tube dependence in 17% of patients alive and free of disease.

Conclusion

Locoregional control, survival, and acute toxicity with this regimen were comparable with other trials utilizing taxanes and/or platins and concomitant conventional or altered fractionation radiation. Our data suggest that chemotherapy added to concomitant boost fractionation may increase rates of long-term feeding tube dependence. Phase III trials are needed to assess the contribution of concomitant boost fractionation to chemoradiotherapy.

Identification of insulin-like growth factor binding protein-3 as a farnesyl transferase inhibitor SCH66336-induced negative regulator of angiogenesis in head and neck squamous cell carcinoma

The farnesyl transferase inhibitor (FTI) SCH66336 has been shown to have antitumor activities in head and neck squamous cell carcinoma (HNSCC) in vitro and in vivo. However, its mechanism of action has not been well defined. Here, we report that the insulin-like growth factor (IGF) binding protein (IGFBP)-3 mediates antitumor activities of SCH66336 in HNSCC by inhibiting angiogenesis. SCH66336 significantly suppressed HNSCC tumor growth and angiogenesis via mechanisms that are independent of H-Ras and RhoB. By inducing IGFBP-3 secretion from HNSCC cells, this compound suppresses angiogenic activities of endothelial cells, including vessel formation in chorioallantoic membranes of chick, endothelial cell sprouting from chick aorta, and capillary tube formation of human umbilical vascular endothelial cells (HUVEC). Knockdown of IGFBP-3 expression in HNSCC cells by RNA interference or depletion of IGFBP-3 in HUVECs by neutralizing antibody effectively blocked the effects of IGFBP-3 secreted from SCH66336-treated HNSCC cells on HUVECs. These findings suggest that IGFBP-3 could be a primary target for antitumor activities of FTIs and that IGFBP-3 is an effective therapeutic approach against angiogenesis in HNSCC.

A phase I/II study of neoadjuvant chemotherapy followed by radiation with boost chemotherapy for advanced T-stage nasopharyngeal carcinoma

PURPOSE

Local recurrence is the most common site of failure for locally advanced nasopharyngeal carcinoma (NPC) treated with neoadjuvant cisplatin/5-fluorouracil (PF) and definitive radiation at our center. Based on this, we studied the addition of chemotherapy during the boost phase of radiation after neoadjuvant PF for advanced T-stage (T3-T4) NPC. This strategy was based on theoretical radiosensitization with chemotherapy during accelerated repopulation of the tumor with relatively radioresistant clonogens.

METHODS AND MATERIALS

Three cycles of neoadjuvant PF was followed by conventionally fractionated radiation with additional PF during the boost portion of the radiation course. An initial Phase I study was done to establish the maximum tolerated dose of concurrent PF.

RESULTS

Forty-four patients were enrolled. Six patients in Phase I defined the MTD for concurrent PF as: cisplatin 10 mg/m2/day and PF 320 mg/m2/day, on Days 1-5 during Weeks 6 and 7 of radiation therapy based on dose-limiting toxicities of mucositis, neutropenia, and thrombocytopenia. Forty-one patients were treated with concurrent therapy per protocol: complete, partial, and minor responses were seen in 23, 16, and 2 patients, respectively. Progression-free and overall survival rates at 5 years were 55% (95% CI, 41-75%) and 66% (95% CI, 52-85%), respectively. Seven of 11 tumor-related deaths were due to local recurrence. Nine of 10 patients with local recurrence had T4-stage disease at presentation. Local control of T4 disease was achieved in 74% of patients overall, and in 25% (1/4) with World Health Organization (WHO) type 1, 76% (16/21) with WHO type 2, and 90% (9/10) with WHO type 3 histology. Common toxicities included mucositis, dermatitis, fatigue, vomiting, and weight loss.

CONCLUSIONS

This regimen was feasible and associated with promising overall survival. Local recurrence remains the major reason for treatment failure in advanced T-stage NPC, especially WHO types 1 and 2. Other strategies to improve local control in these patients should be investigated.

Farnesyltransferase Inhibitor SCH66336 Induces Rapid Phosphorylation of Eukaryotic Translation Elongation Factor 2 in Head and Neck Squamous Cell Carcinoma Cells

Farnesyltransferase inhibitors (FTI) are a class of therapeutic agents designed to target tumors with mutations of the ras oncogene. However, the biological effect of FTIs is often independent of ras mutation status, which suggests the existence of additional mechanisms. In this study, we investigated the molecular effects of SCH66336, an FTI, in head and neck squamous cell carcinoma cells using proteomic approaches. We showed that SCH66336 induced phosphorylation (inactivation) of eukaryotic translation elongation factor 2 (eEF2), an important molecule for protein synthesis, as early as 3 hours after SCH66336 administration. Protein synthesis was subsequently reduced in the cells. Paradoxically, activation of eEF2 kinase (eEF2K), the only known kinase that regulates eEF2, was observed only at 12 hours after SCH66336 treatment. Consistent with this observation, the inhibition of phosphorylated-MEK and phosphorylated-p70S6K, the two key signaling molecules responsible for activation of eEF2K, also occurred at least 12 hours after SCH66336 administration. Our data suggest that inhibition of protein synthesis through inactivation of eEF2 is a novel mechanism of SCH66336-mediated growth inhibition and that this effect is independent of ras-MEK/p70S6K-eEF2K signaling cascades.

Phase I Study of the Farnesyltransferase Inhibitor BMS-214662 Given Weekly in Patients with Solid Tumors

Purpose: A phase I trial of BMS-214662, a selective farnesyltransferase inhibitor with significant preclinical antitumor activity in which drug was given as a weekly 1-hour infusion for four of six weeks, was conducted to evaluate the tolerability, pharmacokinetics, and pharmacodynamic effect on farnesyltransferase activity in peripheral blood mononuclear cells.

Experimental Design: BMS-214662 was given to 27 patients with solid tumors at 10 escalating dose levels (28-220 mg/m2) allowing intrapatient dose escalation; pharmacokinetics and pharmacodynamics were done at the first seven dose levels.

Results: Grade 4 neutropenia (four patients) was the most common dose-limiting toxicity followed by aminotransferase elevation (grade 3 alanine aminotransferase and grade 4 aspartate aminotransferase) and grade 3 dehydration. Most frequent toxicities were neutropenia in 11 (14%), anemia in 15 (19%), fatigue in 9 (12%), and nausea and diarrhea in 6 (8%) of courses, respectively. One minor response lasting 18 weeks in a patient with non–small cell lung cancer, serum calcitonin level reduction accompanied by disease stabilization in two of four patients with medullary thyroid carcinoma, and stable disease in 16 of 25 evaluable patients was seen. No correlation was observed between dose and Cmax, total body clearance (mean, 26.15 ± 10.88 L per hour per m2), volume of distribution at steady state (mean, 39.51 ± 17.91 L/m2), or half-life (mean, 2.63 ± 1.81 hours); a moderate correlation existed between dose given and systemic drug exposure (AUC). Substantial inhibition of peripheral blood mononuclear cell farnesyltransferase activity but near complete recovery by 24 hours was seen.

Conclusion: BMS-214667 was well tolerated as a weekly 1-hour i.v. infusion for four of six weeks with evidence of pharmacodynamic effect. The study was terminated before maximum tolerated dose was reached. Alternative schedules of drug administration might result in improved pharmacodynamic profile.