A Phase 2 Trial of Alternative Volumes of Oropharyngeal Irradiation for De-intensification (AVOID): Omission of the Resected Primary Tumor Bed After Transoral Robotic Surgery for Human Papilloma Virus-Related Squamous Cell Carcinoma of the Oropharynx

PURPOSE

This trial tested the safety and efficacy of a novel, deintensified radiation therapy (RT) approach after initial surgical resection for patients with human papilloma virus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC).

METHODS AND MATERIALS

This single-arm phase 2 prospective clinical trial enrolled 60 patients with stage pT1-pT2 N1-3 HPV-associated OPSCC treated with transoral robotic surgery (TORS) and selective neck dissection at a single institution between May 2014 and September 2017. Patients had favorable features at the primary site (negative surgical margins ≥2 mm, no perineural invasion, and no lymphovascular invasion) but required adjuvant therapy based on lymph node involvement. Surgeries were all performed at a high-volume head and neck cancer center with expertise in TORS. Patients received postoperative RT to at-risk areas in the involved neck (60-66 Gy) and uninvolved neck (54 Gy). The resected primary site was treated as an active avoidance structure in the treatment planning of postoperative RT. Concurrent chemotherapy was administered for patients with extranodal extension.

RESULTS

Median follow-up of the 60 patients enrolled was 2.4 years (range, 8.5-53.8 months). A single patient recurred at the primary site, for 2-year local control of 98.3%. One patient (1.7%) developed a regional neck recurrence, and 2 patients (3.3%) developed distant metastases. Measured 2-year local recurrence-free survival was 97.9% (95% confidence interval, 86.1%-99.7%). Overall survival was 100% at the time of analysis. The mean radiation dose to the primary site was 36.9 Gy (standard deviation, 10.3 Gy). Two patients (3.3%) experienced late soft tissue necrosis in the primary site surgical bed that resolved within 2 months. Feeding tube dependence rates were 0% during RT, 3.3% temporarily during follow-up, and 0% at last follow-up.

CONCLUSIONS

Deintensified postoperative RT that avoids the resected primary tumor site and targets only the at-risk neck after TORS for selected patients with HPV-associated OPSCC may be safe and is worthy of further study.

Novel approach using ultrasonic bone curettage and transoral robotic surgery for en bloc resection of cervical spine chordoma: case report

Chordomas are rare, locally aggressive neoplasms that develop from remnants of the notochord. The typical approach to chordomas of the clivus and axial cervical spine often limits successful en bloc resection. In this case report, authors describe the first-documented transoral approach using both transoral robotic surgery (TORS) for exposure and the Sonopet bone scalpel under navigational guidance to achieve en bloc resection of a cervical chordoma. This 27-year-old man had no significant past medical history (Charlson Comorbidity Index 0). During a trauma workup following a motor vehicle collision, a CT of the patient's cervical spine demonstrated an incidental 2.2-cm lesion situated along the posterior aspect of the C2 vertebral body. Postoperative imaging showed successful en bloc resection with adequate placement of hardware, and the pathology report demonstrated negative resection margins. The patient tolerated the procedure well, and because of the successful en bloc resection, radiation has been deferred. At 7 months postoperatively, the patient returned to work in New York City. Contrasted MRI at 15 months postoperatively showed the patient to be disease free. This approach offers a promising way forward in the treatment of these complex tumors.

Abstract P5-05-01: Metabolic enzyme PFKFB4 activates transcriptional coactivator SRC-3 to drive aggressive metastatic breast cancer

Background: Metabolic rewiring is one of the central hallmarks of cancer progression and survival to support anabolic and energetic demands. Tumor cells constantly alter their metabolic state in response to oncogenic stimuli, nutrient availability, and interaction with immune cells however the precise regulation that precedes the metabolic alteration is poorly understood. Here we report a direct interaction of glycolytic enzyme PFKFB4 with transcriptional coregulator SRC-3. PFKFB4 functions as a critical regulator of Warburg effect and our study reveals that upon glucose stimulation PFKFB4 activates SRC-3 driving an invasive-metastatic breast cancer.

Methods: Molecular experiments were performed to understand the transcriptional activation of SRC-3 by PFKFB4 enzyme. Chromatin immunoprecipitation and gene expression studies were performed to investigate the functions of PFKFB4/SRC-3 crosstalk on transcriptional regulation. Metabolomics and isotope tracing studies were performed to identify the metabolic adaptations regulated by PFKFB4/SRC-3 in breast tumors. PFKFB4-knockout was established using CRISPR-Cas9 system and functional studies were carried out to define its role in tumor cell proliferation, invasion-migration, and breast to lung metastasis. Human breast tumor samples were evaluated to identify the clinical importance of PFKFB4/SRC-3 crosstalk in patients.

Results:Molecular studies revealed that PFKFB4 enzyme phosphorylates SRC-3 at serine 857 (S857) enhancing its transcriptional activity, whereas either suppression of PFKFB4 or ectopic expression of a phosphorylation-deficient SRC-3 mutant S857A (SRC-3S857A) significantly abolished SRC-3-mediated transcriptional output (p<0.000001). Functionally, PFKFB4-driven SRC-3 activation drives glucose flux towards the pentose phosphate pathway enabling purine synthesis by transcriptionally upregulating the expression of enzyme transketolase (TKT). Deletion of PFKFB4 by CRISPR-Cas9 system resulted in significantly reduced proliferation (p<0.05) and migration-invasion (p<0.001) compared to wildtype breast tumor cells. Ablation of SRC-3 or PFKFB4 suppressed in vivo breast tumor growth and prevents metastasis to the lung from an orthotopic setting (p<0.0001). PFKFB4 and phosphorylated SRC-3 levels are significantly increased in breast tumors (p=0.02), whereas, in patients with the basal subtype, PFKFB4 and SRC-3 drive a common protein signature that correlates with the poor survival of TNBC patients (p=0.03).

Conclusion:Our data suggest that the Warburg pathway enzyme PFKFB4 acts as a molecular fulcrum that couples sugar metabolism to transcriptional activation by stimulating SRC-3 to promote aggressive metastatic tumors. It also provides first evidence how Warburg pathway drives aggressive breast tumorigenesis by directly activating powerful oncogene SRC-3. Our work suggests that targeting the PFKFB4–SRC-3 axis may be therapeutically valuable in breast tumors that are notably dependent on glucose metabolism.

(This work is funded by grants from Susan G. Komen and NCI to S.D.)

Citation Format: Dasgupta S, Anand V, John H, Sawant Dessai A, Katsuta E, Takabe K, O'Malley B. Metabolic enzyme PFKFB4 activates transcriptional coactivator SRC-3 to drive aggressive metastatic breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-05-01.

Advances in nano-based inner ear delivery systems for the treatment of sensorineural hearing loss

Sensorineural hearing loss (SNHL) is one of the most common diseases, accounting for about 90% of all hearing loss. Leading causes of SNHL include advanced age, ototoxic medications, noise exposure, inherited and autoimmune disorders. Most of SNHL is irreversible and managed with hearing aids or cochlear implants. Although there is increased understanding of the molecular pathophysiology of SNHL, biologic treatment options are limited due to lack of noninvasive targeted delivery systems. Obstacles of targeted inner ear delivery include anatomic inaccessibility, biotherapeutic instability, and nonspecific delivery. Advances in nanotechnology may provide a solution to these barriers. Nanoparticles can stabilize and carry biomaterials across the round window membrane into the inner ear, and ligand bioconjugation onto nanoparticle surfaces allows for specific targeting. A newer technology, nanohydrogel, may offer noninvasive and sustained biotherapeutic delivery into specific inner ear cells. Nanohydrogel may be used for inner ear dialysis, a potential treatment for ototoxicity-induced SNHL.

Risk of fatal cerebrovascular accidents after external beam radiation therapy for early-stage glottic laryngeal cancer

BACKGROUND

This study compared the risk of fatal cerebrovascular accidents (CVAs) in patients with early-stage glottic laryngeal cancer receiving surgery or external beam radiation therapy (EBRT).

METHODS

Using a competing risks survival analysis, we compared the risk of death because of CVA among patients with early-stage glottic laryngeal cancer receiving surgery or EBRT in the Surveillance, Epidemiology, and End Results (SEER) database.

RESULTS

The cumulative incidence of fatal CVA at 15 years was higher in patients receiving EBRT (2.8%; 95% confidence interval [CI], 2.3% to 3.4%) compared to surgery (1.5%; 95% CI, 0.8% to 2.3%; p = .024). In multivariable competing risks regression models, EBRT remained associated with an increased risk of fatal CVA compared to surgery (adjusted hazard ratio [HR], 1.75; 95% CI, 1.04-2.96; p = .037).

CONCLUSION

Treatment for early-stage glottic laryngeal cancer with EBRT was associated with a small increase in the risk of late fatal CVA events relative to surgery.

Abstract 1474: An RNAi-based functional classification of lung cancer reveals recurring subgroups strongly correlated with EMT status

Introduction: Personalized therapeutic approaches which stratify patients into subgroups based on mutation, amplification, or expression profiles have proven effective. Previously, we showed that mRNA expression profiling of nuclear receptors (NRs) segregated NSCLC patients into prognostic groups. Using a gene-library knockdown strategy, we aim to demonstrate the diagnostic and therapeutic value of NRs and their co-regulators (Co-Regs).

Aims and Methods: We used a large panel of lung and breast cell lines of various types to develop a patient stratification scheme based on functional/survival response to pooled siRNA “mini” library screens. The first siRNA mini-library consists of 48 NR and 72 CoReg targets. Screens were performed in triplicate across a panel of 54 lung cancers (NSCLC and SCLC), 20 breast cancers, 6 immortalized human bronchial epithelial cell lines (HBECs), and a series of oncogenically progressed HBECs. Each triplicate assay was repeated three times using optimized transfection conditions and followed by statistical analysis (r>0.83 for replicate screens). A second siRNA library targeting 53 chromatin remodelers, 26 jumonji enzymes, and 23 palmitoyl transferases was also screened against these same lines using the same protocol.

Results and Conclusions:

1) Response (inhibition or stimulation of growth) to any given siRNA knockdown was heterogeneous across the panel, reflecting the high degree of genetic/functional variability between cancer lines.

2) 85% of the siRNA knockdowns reduced viability in at least one tumor line. Several knockdowns demonstrated selective killing of a significant portion of the cancer lines but not the “normal” HBECs. Many knockdowns differentially affected subsets of cell lines (suggesting possible personalized therapeutics) while others uniformly affected nearly the entire panel.

3) Screening a series of oncogenically progressed HBECs (with p53, KRAS, LKB1) revealed new vulnerabilities detected by a change in response to NR/CoReg knockdown, highlighting the underlying biological changes accompanying oncogenesis.

4) Unexpectedly, we found that classification of the tumor cells by the NR/CoReg mini-library was similar to the classification derived from the second library. The two libraries independently produced a similar subgrouping of the tumor panel. Combined analysis of the two libraries found similar groups.

5) Although there was no obvious correlation between oncogenotypes or mRNA expression of individual NRs or CoRegs, one subgroup (n=26) consisted almost exclusively of lines that had undergone EMT, suggesting possible subtypes of mesenchymal cells.

We conclude that siRNA-minilibrary screens targeting NRs, CoRegs, and chromatin remodeling genes provide a new functional classification of lung and breast cancer with strong translational potential. Work funded by CPRIT.

Citation Format: Ryan Carstens, Kenneth Huffman, Shuguang Wei, Luc Girard, Yang Xie, Sandra Hofmann, Ignacio Wistuba, Suzanne Fuqua, Bruce Posner, Adi F. Gazdar, Steven Kliewer, Bert O'Malley, David Mangelsdorf, John D. Minna. An RNAi-based functional classification of lung cancer reveals recurring subgroups strongly correlated with EMT status. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1474. doi:10.1158/1538-7445.AM2013-1474

Abstract P4-08-09: Targeting Thyroid Receptor b in Estrogen Receptor Negative Breast Cancer

Background: The treatment of estrogen receptor (ER)-negative breast cancer (BC) is a major clinical problem due to the lack of useful therapeutic targets. Nuclear receptors (NRs) are potential targets in these patients because they regulate global transcriptional events and many already have agonists/antagonists available.

Material and Methods: We used microarray analysis of 227 ER-negative tumors to identify NR targets, and performed hierarchical clustering using 41 NRs. Expressed receptors were scored using prediction analysis of microarrays (PAM) across clustered groups. Cell lines were matched to subtypes using previously described data (Neve et al. 2006). Candidate gene expression levels were confirmed by qRT-PCR using TaqMan probes. pGIPZ lentiviral vectors encoding shRNA were used to knockdownselected candidates. MTT and soft agar assays were used to measure chemosensitivity and growth following treatment with Docetaxel (Doc), Doxorubicin (Dox), or Cisplatin (Cis). Statistical analysis was performed using Red-R.

Results: The 41 NRs clustered tumors into 5 groups. For each group we selected genes representing the highest ranked discriminators, and examined their effects in cell lines matching each groups' gene signature. Thyroid hormone receptor b (THRβ) was selected from group V. The expression levels of this receptor were confirmed by qRT-PCR and Western blot analysis.

Knockdown of THRβ in ER-negative HCC2185 cells rendered cells more resistant to all chemotherapeutics by using MTT assay. Similar results were confirmed in ER-negative MDA-MB-453 and HCC202 cells. Knockdown of THRβ enhanced colony forming potential in anchorage-independent soft agar assays in MDA-MB-453 and HCC202 cells. Statistical analysis using clinical data from Sabatier et al. (BCRT 2011) showed that patients with low THRb have a worse clinical outcome. In order to translate these findings into the clinic, we treated cells with a specific THRβ agonists, GC-1 and KB-141. GC-1 inhibited cell growth in growth assays, and synergistic effects were observed when cells were treated with GC-1 and Docetaxel in combination. Re-expression of ERα protein was observed in ER-nagative cells lines after treatment with GC-1 and KB141, suggesting that modulation of THRβ may also extend hormonal therapy to this hormonally insensitive group of patients.

Conclusion: Clinical targeting of NRs in ER-negative BCs is a novel strategy since receptors can be specifically targeted with ligands. Our data suggest that chemotherapy response in ER-negative patients overexpressing THRβ could be enhanced with a THRβ agonist. Similarly, functional re-activation of ERα by activating THRβ might extend hormonal therapies to these patients as well.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-08-09.

Abstract 5757: A new functional classification of lung and breast cancers based on siRNA mediated knockdown of 48 NRs and 72 CoRegulators

Introduction: Nuclear receptors (NRs) and their co-regulators (CoRegs) are master regulators of key transcriptional processes important in cancer pathogenesis and could provide molecular biomarkers for prognosis and personalizing new cancer targeted therapy. Aims and Methods: Our goal is to functionally classify a panel of 54 lung cancer, 20 breast cancer, and several immortalized human lung and breast epithelial cell strains based on their growth and survival response to siRNA mediated knockdown of 48 NRs and 72 CoRegs. Following knockdown of individual NR/CoRegs, changes in growth patterns are quantified and statistical methods are used to identify disease subgroups of similar responders. These subgroups are then integrated with our legacy datasets for clinical demographics, cancer cell oncogenotype and genome wide molecular characterization, and responses to standard and targeted chemotherapy. Results and Conclusions: A diverse, representative panel consisting of lung cancer, breast cancer, and normal epithelial cell lines was tested by siRNA transfection. After optimization to determine transfection conditions, all cell lines were screened using a focused siRNA library targeting all 48 NRs and 72 CoRegs (each gene is targeted by pools of 4 different siRNAs, Qiagen). Screening experiments were performed in triplicate, in 96 well plates, in a five-day MTS assay and assays were repeated 3 times. Correlation between replicates for the same cell line is >0.84 and knockdowns were validated by qRT-PCR. We found: 1) NR/CoReg-specific knockdown could have no effect, increase, or decrease tumor cell viability in a cell line dependent manner. 2) Overall ∼70% of the NRs or CoRegs reduced cell viability in at least one tumor line when their expression was knocked down (examples included NURR1, PRMT1, RXRalpha, BRCA1). 3) NR/CoReg-specific tumor cell toxicity was validated independently by siRNA knockdown combined with a liquid colony formation assay. 4) Knockdown of several NR/CoRegs selectively killed tumor but not normal epithelial cells. 5) Tumor cell lines could be stratified into functionally unique categories based on their changes in growth following NR/CoReg-specific knockdowns. We conclude that siRNA mediated knockdown of a large number of NRs and their CoRegs identifies genes that show tumor cell selective toxicity, and that tumor lines vary in their siRNA response phenotypes. These data strengthen the concept for NR/CoReg targeted therapy of lung and breast cancer and also the need to “personalize” such therapy.

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 5757. doi:1538-7445.AM2012-5757

Abstract 1083: Nuclear receptors as novel targets in ER negative breast cancer

Background: Estrogen negative (ER-) breast cancer is the major clinical problem in breast cancer treatment due to the limited useful targets in ER- breast cancer. Nuclear receptors are good targets in ER- breast cancer because of the availibility of agonists and antagonists. Material and methods: We used microarray analysis of 227 ER-negative tumors to identify nuclear receptor (NR) targets, and performed hierarchical clustering using 41 NR's. Contributing receptors were scored using prediction analysis of microarrays (PAM) across clustered groups. The candidates gene expression levels were confirmed by qRT-PCR using TaqMan probes. pGIPZ lentiviral vectors carrying shRNA were used to knockdown the selected receptors. Cells were treated with Docetaxel, Doxorubicin and Cisplatin for three days and MTT growth assay was used to evaluate the knockdown effect on cells proliferation and chemosensitivity. Statistical analysis was performed using Red-R software. Results: The 41 NRs clustered the tumors into 5 distinct groups. Groups III and V were chosen according to the higher representative percentage of patients (61%). For each group we selected 4 genes that were the highest ranked discriminators of the group and three cell lines which match each groups’ signature. Thus, testicular receptor 2 (TR2), testicular receptor 4 (TR4), GCNF and RevErbb receptors were selected from group III and androgen receptor, thyroid hormone receptor beta (THRB), COUP-TF1 and ESRRg receptors were selected from group V. The expression levels of the selected receptors were confirmed by q-RT-PCR. The knockdown of TR2 in HCC38 cell line (group III) rendered cells more sensitive to Docetaxel or Doxorubicin. However, the knockdown of TR4 rendered cells more resistant to all the 3 chemotherapy drugs. TR2 knockdown dramatically downregulated TR4 gene expression, whereas TR4 knockdown upregulated TR2 expression suggesting that TR2 maybe the dominant factor in chemotherapeutic response. Knockdown of THRB in HCC 2185 cells (group V), rendered cells more resistant to chemotherapy drugs while THRB agonist could be able to reverse the resistance. Interestingly, COUP-TFI was upregulated in THRB knock down cells. Statistic analysis using clinical data from Sabatier R., BCRT 2011 showed that patients with low THRB or higher COUP-TFI have worse outcome. Conclusion: Clinical targeting of NRs in selected ER-negative breast cancers may be an interesting alternative therapy since more and more agonists and antagonists are being available. The clinical data showed that THRB and COUP-TF1 could be used as predictive factors for the outcome. The use of agonists (for THRB for example) or antagonists (for TR2 for example) combined with chemotherapy could be conceivable in the future.

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 1083. doi:1538-7445.AM2012-1083

Use of e-learning to enhance medical students' understanding and knowledge of healthcare-associated infection prevention and control

An online infection prevention and control programme for medical students was developed and assessed. There was a statistically significant improvement (P<0.0001) in the knowledge base among 517 students after completing two modules. The majority of students who completed the evaluation were positive about the learning experience.

Abstract 2296: Identification of novel nuclear receptor targets in estrogen receptor negative breast cancer

Introduction: Estrogen receptor (ER)-negative breast cancer has a particularly poor prognosis, and there are limited targeted agents for this subtype.

Aims and Methods: To identify nuclear receptor (NR) targets, we did microarray analysis of 227 ER-negative tumors as assessed by immunohistochemistry, and performed hierarchical clustering using 41 NRs, and prediction analysis of microarrays (PAM) across the clustered groups. Cell lines were matched to identified groups using previously published data. Clinical correlations were made using previously published breast cancer datasets.

Results and Conclusion: The 41 NRs clustered the tumors into 5 distinct groups. We found that the androgen receptor (AR) was the highest ranked discriminator of these groups followed by ERα. Group 1 (14% of the tumors) was characterized by elevated ERRα and RXR expression. Group 2 (9%) was characterized by higher expression of the orphan receptor NURR1. Group 3 was the largest group (37%), and showed high level expression of PPARα. Group 4 (16%) expressed higher levels of PPARγ. Group 5 (24%) demonstrated particularly high relative expression of AR, and also showed higher expression of ERα and ERRα. We used previously published microarray data to match cell lines to the NR groups using the scoring matrix developed in the PAM analysis. These cell lines are currently being tested for response to NR agonists and antagonists in growth (MTT, soft-agar, mammosphere) and apoptotic assays. We used a previously published microarray data set with long-term follow up information to identify potential differences in outcomes for the different NR subtypes. While we found no significant differences between the groups, the sample size was quite low for each subtype (n∼15 per group).

In summary, we have identified several novel ER-negative tumor groups by different expression level of NRs which may contribute to the prediction of breast cancer molecular subtypes.

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 2296. doi:10.1158/1538-7445.AM2011-2296

Transoral robotic photodynamic therapy for the oropharynx

Photodynamic therapy (PDT) has been used for head and neck carcinomas with little experience in the oropharynx due to technical challenges in achieving adequate exposure. We present the case of a patient with a second right tonsil carcinoma following previous treatment with transoral robotic surgery (TORS) and postoperative chemoradiation for a left tonsil carcinoma. Repeat TORS for the right tonsil carcinoma reviewed multiple positive surgical margins. The power output from the robotic camera was modified to facilitate safe intraoperative three dimensional visualization of the tumor bed. The robotic arms facilitated clear exposure of the tonsil and tongue base with stable administration of the fluence. Real-time measurements confirmed stable photobleaching with augmentation of the prescribed light fluence secondary to light scatter in the oropharynx. We report a potential new role using TORS for exposure and accurate PDT in the oropharynx.

Hormone action in the mammary gland

A woman's breast cancer risk is affected by her reproductive history. The hormonal milieu also influences the course of the disease. The female reproductive hormones, estrogens, progesterone, and prolactin, have a major impact on breast cancer and control postnatal mammary gland development. Analysis of hormone receptor mutant mouse strains combined with tissue recombination techniques and proteomics revealed that sequential activation of hormone signaling in the mammary epithelium is required for progression of morphogenesis. Hormones impinge on a subset of luminal mammary epithelial cells (MECs) that express hormone receptors and act as sensor cells translating and amplifying systemic signals into local stimuli. Proliferation is induced by paracrine mechanisms mediated by distinct factors at different stages. Tissue and stage specificity of hormonal signaling is achieved at the molecular level by different chromatin contexts and differential recruitment of coactivators and corepressors.

Head and neck cancer radiosensitization by the novel poly(ADP-ribose) polymerase inhibitor GPI-15427

BACKGROUND

In this study, we tested the ability of a novel poly(adenosine diphosphate ribose) polymerase (PARP) inhibitor, 10-(4-methyl-piperazin-1-ylmethyl)-2H-7-oxa-1,2-diaza-benzo[de]-anthracen-3-one (GPI-15427), to enhance the effect of radiotherapy in a xenograft model of human head and neck squamous cell carcinoma (HNSCC).

METHODS

Human xenograft HNSCC tumors were established in female nude mice: animals were treated with orally administered GPI-15427 at varied doses prior to tumor irradiation. In vitro and in vivo apoptosis analyses and neutral single-cell gel electrophoresis (comet) assay were performed, with the "tail moment" calculated to evaluate DNA double-strand break damage.

RESULTS

Orally administered GPI-15427 given before radiation therapy significantly reduced tumor volume, and cells demonstrated significantly elevated mean tail moments (indicative of DNA damage) and enhanced apoptosis both in vitro and in vivo, compared with radiation-alone and control groups.

CONCLUSIONS

Use of the PARP-1 inhibitor GPI-15427 induced significant sensitization to radiotherapy, representing a promising new treatment in the management of HNSCC.