Efficacy and comparative effectiveness of sirolimus as an anticancer drug.

OBJECTIVES/HYPOTHESIS: To evaluate antitumor efficacy of the generic mammalian target of rapamycin (mTOR) inhibitor sirolimus in preclinical animal models of head and neck squamous cell carcinoma (HNSCC) and compare its effects with those of the patented analogue temsirolimus. STUDY DESIGN: In vivo study. METHODS: To develop xenograft established tumor model (ETM) of HNSCC, FaDu cells were injected subcutaneously into nude mice. When tumors reached 50 to 60 mm(3), mice were randomized into five groups and treated daily intraperitoneally with sirolimus at various doses for 5 days per week for 3 weeks. Tumor volumes were measured. The results were compared with historical data on temsirolimus effects. In the minimal residual disease (MRD) model, surgical wounds were created and FaDu cells implanted. After 72 hours, animals were randomized into two groups and were injected intraperitoneally with 0 or 5 mg/kg sirolimus for 5 days per week for 30 days. RESULTS: In the ETM, sirolimus significantly inhibited tumor growth (P < .01), although there was no overall significant difference in tumor growth inhibition between sirolimus and temsirolimus. In the MRD model, sirolimus significantly suppressed growth of tumors (P < .001) and improved survival compared with controls (P < .01). There was a significant decrease in pS6 expression, indicating mTOR inhibition. CONCLUSIONS: In this study, we demonstrate that the generic mTOR inhibitor sirolimus shows potent antitumor activity in HNSCC and produces comparable effects to the patent drug temsirolimus. Sirolimus has the potential of serving as an economic and comparative targeted agent to temsirolimus in the treatment of HNSCC.

Curcumin inhibits skin squamous cell carcinoma tumor growth in vivo.

OBJECTIVE: Squamous cell carcinoma (SCCa) has increased from 4% to 10% over 4 decades, stimulating interest in developing novel agents that slow sun-damaged skin progression. This is the first study evaluating the naturally occurring bioactive food compound curcumin on skin cancer xenografts. Low bioavailability of curcumin has slowed its transition to clinical trials. It is hypothesized that curcumin has growth-inhibitory effects through the TOR pathway and chemopreventive potential in skin SCCa where local application could bypass bioavailability problems. STUDY DESIGN: A randomized experimental animal and laboratory study. SETTING: Louisiana State University Health Sciences Center, Shreveport, Louisiana. SUBJECTS AND METHODS: SCID mice were pretreated with 0, 5, or 15 mg of curcumin (n = 8 per group), 3 days prior to injecting 106 SRB12-p9 skin SCCa cells in each flank, and were gavaged daily thereafter. Tumor volumes were measured and tumors were harvested on day 24 when mice were sacrificed. Immunohistochemical analysis of pS6 expression (n = 3 per group) and tumor volumes in the 3 groups were compared using 1-way analysis of variance and pairwise comparisons were determined with the Tukey t test if overall comparisons were significant. RESULTS: Tumor volume increased 2.3 times faster in control mice compared with the group receiving 15 mg of curcumin (P = .0003). A significant difference in average tumor volumes was seen (P = .0012), especially with treatment of 15 mg of curcumin compared with control P = .0003). Curcumin inhibited S6 phosphorylation (P = .0027), suggest-ing inhibition of the MTOR pathway. CONCLUSION: Curcumin appears to inhibit skin SCCa growth and blocks tumor progression by inhibiting pS6 even when gavage is used to deliver curcumin, indicating even more significant effects in future experiments with local application.

Human papillomavirus in metastatic lymph nodes from unknown primary head and neck squamous cell carcinoma.

OBJECTIVE: Determine human papillomavirus (HPV) incidence in unknown primary squamous cell carcinomas (SCCa) of the head and neck and assess if HPV status influenced survival. STUDY DESIGN: Historical cohort study. SETTING: Tertiary care center. SUBJECTS: Patients with unknown primary SCCa despite a complete workup who underwent neck dissection or excisional biopsy and postoperative comprehensive ± chemoradiotherapy between 2002 and 2009. METHODS: HPV fluorescence in situ hybridization (FISH) and p16(INK4a) immunohistochemistry (p16 IHC) were performed. Results were compared with survival, age, race, gender, tobacco use, alcohol use, and nodal stage. RESULTS: Twenty-five patients met the inclusion criteria, of whom 88% were >10 pack year tobacco users. Twenty-eight percent were HPV-positive defined by both p16+ and FISH+. Five-year overall survival was 66.7% in HPV-positive and 48.5% in HPV-negative patients (P = .35). Similarly, 5-year disease-free survival rates were 66.7% in HPV-positive and 48.5% in HPV-negative patients (P = .54). All 3 HPV-positive nonsmokers were survivors, but this was not significant because of the small sample size (P > .05). No other characteristics were associated with survival (P > .05). CONCLUSION: Twenty-eight percent of metastatic lymph nodes from occult primary tumors were HPV positive. There was no survival difference associated with HPV status. Most of the HPV-positive patients in this study were tobacco users who had similar survival to HPV-negative patients, so caution should be used in interpreting HPV status in these patients.

Teasing out the best molecular marker in the AKT/mTOR pathway in head and neck squamous cell cancer patients.

OBJECTIVES/HYPOTHESIS: No reliable molecular biomarker is currently available for clinical application in the management of head and neck cancer patients. The AKT/mTOR pathway is activated in 90% to 100% of head and neck squamous cell cancer (HNSCC) and could be promising biomarkers closely linked to cancer incidence. STUDY DESIGN: Retrospective study of HNSCC and non-cancer patients. METHODS: Oral mucosa from noncancer patients were compared to HNSCC tumors and junctional zone mucosa. The candidate biomarkers mTOR, AKT, 4EBP1, and S6 kinase, signaling components upstream and downstream of mTOR that appear dysregulated in HNSCC, were evaluated using immunohistochemistry (IHC) and Western blot analysis. RESULTS: Expression of phosphorylated AKT and phosphorylated mTOR were significantly higher in cancer patient tumors compared to noncancer oral mucosa samples (P = .004 and P = .026, respectively) by Western blot analysis. Expression of p-mTOR and p-4EBP1 were higher in patient junctional zones compared to tumors (p = 0.017 and p = 0.022, respectively) and no difference in p-AKT or p-S6 expression in HNSCC patients' junctional zone compared to tumors. IHC-demonstrated p-mTOR expression was 81.9% sensitive and 100% specific in differentiating cancer from noncancer mucosa, whereas p-4EBP1 expression by IHC was only 50.0% sensitive and 95.5% specific in differentiating normal mucosa from HNSCC (P < .01). CONCLUSIONS: Phosphorylated mTOR appears to be a reliable biomarker by both Western blot analysis (P = .026) and IHC in human head and neck cancer (P < .001). Moreover, phosphorylated AKT, which is immediately upstream of mTOR, is a potential biomarker that should be further studied. Clinical trials with mTOR inhibitors are being evaluated for HNSCC, and selecting patients that are likely to respond to these inhibitors requires identifying and validating predictive biomarkers of response.