Molecular phenotype predicts sensitivity of squamous cell carcinoma of the head and neck to epidermal growth factor receptor inhibition

Multi-kinase compensation rescues EGFR knockout in a cell line model of head and neck squamous cell carcinoma

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is a debilitating disease with poor survival rates. While the epidermal growth factor receptor (EGFR)-targeting antibody Cetuximab is approved for treatment, responses are limited and the molecular mechanisms driving resistance remain incompletely understood.

METHODS

To better understand how cells survive without EGFR activity, we developed an EGFR knockout derivative of the UM-SCC-92 cell line using CRISPR/Cas9 technology. We then characterized changes to the transcriptome with RNAseq and changes in response to kinase inhibitors with resazurin cell viability assays. Finally, we tested if inhibitors with activity in the EGFR knockout model also had synergistic activity in combination with EGFR inhibitors in either wild type UM-SCC-92 cells or a known Cetuximab-resistant model.

RESULTS

Functional and molecular analysis showed that knockout cells had decreased cell proliferation, upregulation of FGFR1 expression, and an enhanced mesenchymal phenotype. In fact, expression of common EMT genes including VIM, SNAIL1, ZEB1 and TWIST1 were all upregulated in the EGFR knockout. Surprisingly, EGFR knockout cells were resistant to FGFR inhibitor monotherapies, but sensitive to combinations of FGFR and either XIAP or IGF-1R inhibitors. Accordingly, both wild type UM-SCC-92 and Cetuximab-resistant UM-SCC-104 cells with were sensitive to combined inhibition of EGFR, FGFR and either XIAP or IGF-1R.

CONCLUSIONS

These data offer insights into EGFR inhibitor resistance and show that resistance to EGFR knockout likely occurs through a complex network of kinases. Future studies of cetuximab-resistant HNSCC tumors are warranted to determine if this EMT phenotype and/or multi-kinase resistance is observed in patients.

Pharmacological PI3K inhibition in head and neck squamous cell carcinoma: A systematic review

BACKGROUND

This systematic review aimed to investigate the in vitro and in vivo effects of phosphatidylinositol-3-kinase (PI3K) inhibitors on head and neck squamous cell carcinoma (HNSCC). Considering the role of PI3K and its downstream effectors in cell proliferation, invasion, and survival, it is reasonable to expect that treatment with PI3K inhibitors could control HNSCC onset and progression. Thus, the research question for our review was whether pharmacological inhibition of PI3K affects HNSCC progression.

METHODS

In vitro and in vivo studies were selected from six databases. We collected data regarding cell viability, apoptosis, and the regulation of protein expression levels from in vitro studies. For the in vivo studies, we analyzed the reduction in tumor size or gene and protein expression.

RESULTS

The included studies showed reduced cell proliferation and apoptosis after treatment with PI3K inhibitors. PI3K inhibitors in combination with other drugs had an enhanced anticancer effects compared to those of single-drug treatments.

CONCLUSIONS

The results support the potential of PI3K inhibitors as candidates for clinical trials in HNSCC.

Small molecule profiling to define synergistic EGFR inhibitor combinations in head and neck squamous cell carcinoma

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is a debilitating disease with poor survival. Although epidermal growth factor receptor (EGFR)-targeting antibody cetuximab improves survival in some settings, responses are limited suggesting that alternative approaches are needed.

METHODS

We performed a high throughput drug screen to identify EGFR inhibitor-based synergistic combinations of clinically advanced inhibitors in models resistant to EGFR inhibitor monotherapies, and then performed downstream validation experiments on prioritized synergistic combinations.

RESULTS

From our screen, we re-discovered known synergistic EGFR inhibitor combinations with FGFR or IGF-1R inhibitors that were broadly effective and also discovered novel synergistic combinations with XIAP inhibitor and DNMT inhibitors that were effective in only a subset of models.

CONCLUSIONS

Conceptually, our data identify novel synergistic combinations that warrant evaluation in future studies, and suggest that some combinations, although highly synergistic, will require parallel companion diagnostic development to be effectively advanced in patients.

PIK3CA Gene Mutations in HNSCC: Systematic Review and Correlations with HPV Status and Patient Survival

PIK3CA mutations are believed to contribute to the pathogenesis of human papillomavirus (HPV)-associated head and neck squamous cell carcinomas (HNSCC). This study aims to establish the frequency of PIK3CA mutations in a Portuguese HNSCC cohort and to determine their association with the HPV status and patient survival. A meta-analysis of scientific literature also revealed widely different mutation rates in cohorts from different world regions and a trend towards improved prognosis among patients with PIK3CA mutations. DNA samples were available from 95 patients diagnosed with HNSCC at the Portuguese Institute of Oncology in Lisbon between 2010 and 2019. HPV status was established based on viral DNA detected using real-time PCR. The evaluation of PIK3CA gene mutations was performed by real-time PCR for four mutations (H1047L; E542K, E545K, and E545D). Thirty-seven cases were found to harbour PIK3CA mutations (39%), with the E545D mutation (73%) more frequently detected. There were no significant associations between the mutational status and HPV status (74% WT and 68% MUT were HPV (+); p = 0.489) or overall survival (OS) (3-year OS: WT 54% and MUT 65%; p = 0.090). HPV status was the only factor significantly associated with both OS and disease-free survival (DFS), with HPV (+) patients having consistently better outcomes (3-year OS: HPV (+) 65% and HPV (-) 36%; p = 0.007; DFS HPV (+) 83% and HPV (-) 43%; p = 0.001). There was a statistically significant interaction effect between HPV status and PIK3CA mutation regarding DFS (Interaction test: p = 0.026). In HPV (+) patients, PIK3CA wild-type is associated with a significant 4.64 times increase in the hazard of recurrence or death (HR = 4.64; 95% CI 1.02-20.99; p = 0.047). Overall, PIK3CA gene mutations are present in a large number of patients and may help define patient subsets who can benefit from therapies targeting the PI3K pathway. The systematic assessment of PIK3CA gene mutations in HNSCC patients will require further methodological standardisation.

Combined EGFR1 and PARP1 Inhibition Enhances the Effect of Radiation in Head and Neck Squamous Cell Carcinoma Models

Head and neck squamous cell carcinoma (HNSCC) is a challenging cancer with little change in five-year overall survival rate of 50-60% over the last two decades. Radiation with or without platinum-based drugs remains the standard of care despite limited benefit and high toxicity. HNSCCs often overexpress epidermal growth factor receptor (EGFR) and inhibition of EGFR signaling enhances radiation sensitivity by interfering with repair of radiation-induced DNA breaks. Poly (adenosine diphosphate-ribose) polymerase-1 (PARP1) also participates in DNA damage repair, but its inhibition provides benefit in cancers that lack DNA repair by homologous recombination (HR) such as BRCA-mutant breast cancer. HNSCCs in contrast are typically BRCA wild-type and proficient in HR repair, making it challenging to apply anti-PARP1 therapy in this model. A recently published study showed that a combination of EGFR and PARP1 inhibition induced more DNA damage and greater growth control than each single agent in HNSCC cells. This led us to hypothesize that a combination of EGFR and PARP1 inhibition would enhance the efficacy of radiation to a greater extent than each single agent, providing a rationale for paradigm-shifting combinatorial approaches to improve the standard of care in HNSCC. Here, we report a proof-of-concept study using Detroit562 HNSCC cells, which are proficient for DNA repair by both HR and non-homologous end joining (NHEJ) mechanisms. We tested the effect of adding cetuximab and/or olaparib (inhibitors of EGFR and PARP1, respectively) to radiation and compared it to that of cisplatin and radiation combination, which is the standard of care. Our results demonstrate that the combination of cetuximab and olaparib with radiation was superior to the combination of any single drug with radiation in terms of induction of unrepaired DNA damage, induction of senescence, apoptosis and clonogenic death, and tumor growth control in mouse xenografts. Combined with our recently published phase I safety data on cetuximab/olaparib/radiation triple combination, the data reported here demonstrate a potential for combining biologically-based therapies that might optimize radiosensitization in HNSCC.

Integrated Molecular Profiling as an Approach to Identify PI3K Inhibitor Resistance Mechanisms

The identification of drug resistance pathways and approaches to target these pathways remains a significant and important challenge in cancer biology. Here, we address this challenge in the context of ongoing efforts to advance phosphatidylinositol 3-kinase (PI3K) inhibitors for the treatment of PI3K-aberrant cancers. While PI3K inhibitors have had tremendous success in some diseases, such as breast cancer, early clinical trials in other malignancies, such as head and neck squamous cell carcinoma (HNSCC), have not had the same level of success. Since HNSCC and other cancers display relatively high PI3K pathway alteration rates (>45%), these underwhelming results suggest that additional or unexpected factors may contribute to the lower response rates. Here, we highlight some of the emerging functional genomic and sequencing approaches being used to identify predictive biomarkers of PI3K inhibitor response using both cancer cell lines and clinical trial specimens. Importantly, these approaches have uncovered both innate genetic and adaptive mechanisms driving PI3K inhibitor resistance. In this chapter, we describe recent technological advances that have revolutionized our understanding of PI3K inhibitor resistance pathways in HNSCC and highlight how these and other approaches lay the groundwork to make significant strides in our understanding of molecular pharmacology in the cancer field.

Dacomitinib and gedatolisib in combination with fractionated radiation in head and neck cancer

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We evaluated radiation with dual EGFR and PI3K targeting in head and neck cancer.

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Dacomitinib, showed an inverse correlation between growth inhibition and EGFR expression.

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Gedatolisib was effective in each cell line. Neither drug caused radiosensitization in vitro.

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Gedatolisib was relatively ineffective in vivo in combination with dacomitinib and/or radiation.

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Dacomitinib was highly effective alone and in combination with radiation and/or gedatolisib.

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Immunoblotting studies in vivo mirrored the effects seen with growth delay.

Background and purpose

There has been little success targeting individual genes in combination with radiation in head and neck cancer. In this study we investigated whether targeting two key pathways simultaneously might be more effective.

Materials and methods

We studied the effect of combining dacomitinib (pan-HER, irreversible inhibitor) and gedatolisib (dual PI3K/MTOR inhibitor) with radiation in well characterized, low passage xenograft models of HNSCC in vitro and in vivo.

Results

Dacomitinib showed differential growth inhibition in vitro that correlated to EGFR expression whilst gedatolisib was effective in both cell lines. Neither agent radiosensitized the cell lines in vitro. In vivo studies demonstrated that dacomitinib was an effective agent alone and in combination with radiation whilst the addition of gedatolisib did not enhance the effect of these two modalities despite inhibiting phosphorylation of key genes in the PI3K/MTOR pathway.

Conclusions

Our results showed that combining two drugs with radiation provided no added benefit compared to the single most active drug. Dacomitinib deserves more investigation as a radiation sensitizing agent in HNSCC.

PRAS40 Phosphorylation Correlates with Insulin-Like Growth Factor-1 Receptor-Induced Resistance to Epidermal Growth Factor Receptor Inhibition in Head and Neck Cancer Cells

EGFR inhibitors have shown poor efficacy in head and neck squamous cell carcinoma (HNSCC) with demonstrated involvement of the insulin-like growth factor-1 receptor (IGF1R) in resistance to EGFR inhibition. IGF1R activates the PI3K-Akt pathway, which phosphorylates proline-rich Akt substrate of 40 kDa (PRAS40) to cease mTOR inhibition resulting in increased mTOR signaling. Proliferation assays separated six HNSCC cell lines into two groups: sensitive to EGFR inhibition or resistant; all sensitive cell lines demonstrated reduced sensitivity to EGFR inhibition upon IGF1R activation. Reverse phase protein microarray analysis and immunoblot identified a correlation between increased PRAS40 phosphorylation and IGFR-mediated resistance to EGFR inhibition. In sensitive cell lines, PRAS40 phosphorylation decreased 44%-80% with EGFR inhibition and was restored to 98%-196% of control by IGF1R activation, while phosphorylation was unaffected in resistant cell lines. Possible involvement of mTOR in this resistance mechanism was demonstrated through a similar pattern of p70S6K phosphorylation. However, addition of temsirolimus, an mTORC1 inhibitor, was insufficient to overcome IGF1R-mediated resistance and suggested an alternative mechanism. Forkhead box O3a (FOXO3a), which has been reported to complex with PRAS40 in the cytoplasm, demonstrated a 6-fold increase in nuclear to cytoplasmic ratio upon EGFR inhibition that was eliminated with concurrent IGF1R activation. Transcription of FOXO3a-regulated TRAIL and PTEN-induced putative kinase-1 (PINK1) was increased with EGFR inhibition in sensitive cell lines; this effect was diminished with IGF1R stimulation. IMPLICATIONS: These data suggest PRAS40 may play an important role in IGF1R-based therapeutic resistance to EGFR inhibition, and this likely occurs via inhibition of FOXO3a-mediated proapoptotic gene transcription.

A Phase 1b Study of Cetuximab and BYL719 (Alpelisib) Concurrent with Intensity Modulated Radiation Therapy in Stage III-IVB Head and Neck Squamous Cell Carcinoma

PURPOSE

Activation of the PI3K/mTOR signaling pathway is common in head and neck squamous cell carcinoma (HNSCC). BYL719 is an α-specific PI3K inhibitor that is synergistic and efficacious when combined with cetuximab, a Food and Drug Administration-approved radiosensitizing agent in the treatment of HNSCC. The agent independently has been shown to enhance radiosensitivity. This study evaluates the addition of BYL719 to cetuximab and radiation in the treatment of locally advanced HNSCC.

METHODS AND MATERIALS

This is a single-institution, phase 1 study. Patients with American Joint Committee on Cancer seventh edition stage III to IVB HNSCC received standard cetuximab (400 mg/m² intravenous loading dose) before intensity modulated radiation therapy (IMRT) followed by 250 mg/m² weekly infusions during IMRT. BYL719 was given orally during IMRT in 3 dose levels: (1) 200 mg/d, (2) 250 mg/d, or (3) 300 mg/d in a standard 3 + 3 dose-escalation design.

RESULTS

Eleven patients were evaluable. Dose level 2 was the maximum tolerated dose for BYL719. Two patients on dose level 3 had dose-limiting toxicities of oral mucositis that required a dose reduction of BYL719. One patient on dose level 2 had a dose-limiting toxicity of nausea that led to withdrawal of on-study treatment. Related grade 3 or higher adverse events consisted of decreased lymphocyte count, oral mucositis, dysphagia, hyperglycemia, maculopapular rash, and palmar-plantar erythrodysesthesia syndrome. All 11 patients had a complete response on posttreatment imaging, and 10 remain disease free. Of the 8 patients with mutational analysis, 1 had an activating PIK3CA mutation associated with a rapid response on serial intratreatment magnetic resonance imaging scans.

CONCLUSIONS

The recommended phase 2 dose of BYL719 is 250 mg/d in combination with cetuximab and IMRT in patients with locally advanced HNSCC. Further evaluation of the addition of BYL719 to the platinum-sparing regimen of cetuximab and IMRT in the treatment of locally advanced HNSCC is warranted.

Antitumor effect of insulin-like growth factor-1 receptor inhibition in head and neck squamous cell carcinoma

OBJECTIVES

The insulin-like growth factor-1 receptor (IGF1R) has been implicated in therapeutic resistance in head and neck squamous cell carcinoma (HNSCC), and small molecule tyrosine kinase inhibitors (TKIs) of IGF1R activity may have anticancer activity. Therefore, the relationship between survival and IGF1R expression was assessed for oral cavity (OC) cancer, and the antitumor effects of two IGF1R-TKIs, OSI-906 and BMS-754807, were evaluated in HNSCC cell lines in vitro.

METHODS

Clinical outcome data and tissue microarray immunohistochemistry were used to generate IGF1R expression-specific survival curves. Immunoblot, alamarBlue proliferation assay, trypan blue exclusion viability test, clonogenic assay, flow cytometry, and reverse phase protein array (RPPA) were used to evaluate in vitro responses to IGF1R-TKIs.

RESULTS

For patients with stage III/IV OCSCC, higher IGF1R expression was associated with poorer overall 5-year survival (P = 0.029). Both BMS-754807 and OSI-906 caused dose-dependent inhibition of IGF1R and Akt phosphorylation and inhibited proliferation; BMS-754807 was more potent than OSI-906. Both drugs reduced HNSCC cell viability; only OSI-906 was able to eliminate all viable cells at 10 μM. The two drugs similarly inhibited clonogenic cell survival. At 1 μM, only BMS-754807 caused a fourfold increase in the basal apoptotic rate. RPPA demonstrated broad effects of both drugs on canonical IGF1R signaling pathways and also inhibition of human epidermal growth factor receptor-3 (HER3), Src, paxillin, and ezrin phosphorylation.

CONCLUSION

OSI-906 and BMS-754807 inhibit IGF1R activity in HNSCC cell lines with reduction in prosurvival and proliferative signaling and with concomitant antiproliferative and proapoptotic effects. Such antagonists may have utility as adjuvants to existing therapies for HNSCC.

LEVEL OF EVIDENCE

NA Laryngoscope, 130:1470-1478, 2020.

Rationale for Using Irreversible Epidermal Growth Factor Receptor Inhibitors in Combination with Phosphatidylinositol 3-Kinase Inhibitors for Advanced Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a common and debilitating form of cancer characterized by poor patient outcomes and low survival rates. In HNSCC, genetic aberrations in phosphatidylinositol 3-kinase (PI3K) and epidermal growth factor receptor (EGFR) pathway genes are common, and small molecules targeting these pathways have shown modest effects as monotherapies in patients. Whereas emerging preclinical data support the combined use of PI3K and EGFR inhibitors in HNSCC, in-human studies have displayed limited clinical success so far. Here, we examined the responses of a large panel of patient-derived HNSCC cell lines to various combinations of PI3K and EGFR inhibitors, including EGFR agents with varying specificity and mechanistic characteristics. We confirmed the efficacy of PI3K and EGFR combination therapies, observing synergy with α isoform-selective PI3K inhibitor HS-173 and irreversible EGFR/ERBB2 dual inhibitor afatinib in most models tested. Surprisingly, however, our results demonstrated only modest improvement in response to HS-173 with reversible EGFR inhibitor gefitinib. This difference in efficacy was not explained by differences in ERBB target selectivity between afatinib and gefitinib; despite effectively disrupting ERBB2 phosphorylation, the addition of ERBB2 inhibitor CP-724714 failed to enhance the effect of HS-173 gefitinib dual therapy. Accordingly, although irreversible ERBB inhibitors showed strong synergistic activity with HS-173 in our models, none of the reversible ERBB inhibitors were synergistic in our study. Therefore, our results suggest that the ERBB inhibitor mechanism of action may be critical for enhanced synergy with PI3K inhibitors in HNSCC patients and motivate further preclinical studies for ERBB and PI3K combination therapies.

Autophagy inhibitors chloroquine and LY294002 enhance temozolomide cytotoxicity on cutaneous melanoma cell lines in vitro

Patients with metastatic melanoma are difficult to treat and have a very poor prognosis because of high resistance to therapy. Recent evidence indicates that tumors could overcome death through autophagy, a survival mechanism, which cancer cells use under lack of energy and nutrient deprivation. Melanoma cells have different sensitivity to temozolomide (TMZ) treatment. In this study, we showed that the combination of autophagy inhibitors chloroquine or LY294002 and TMZ induced enhanced cytotoxicity of alkylating agents on human melanoma cell lines. All assays were performed on patient-derived melanoma cell lines. The effectiveness of the combined treatment of TMZ and autophagy inhibitors was determined using an MTT assay. Next, we analyzed the expression mRNA level of Beclin 1, LC3B, and p62/STSQM1 and the relative expression of LC3B protein under combined treatment. Autophagic flux was determined by analysis of colocalization of Lysotracker Red and LC3B puncta. Apoptosis was measured by Annexin V/PI staining. Cell cycle analyses were carried out by flow cytometry. We showed that autophagy inhibition could enhance melanoma cell death combined with TMZ therapy. Chloroquine synergistically enhanced the TMZ-induced growth arrest and increased the G0/G1 population in Mel Z and Mel IL cell lines, but not Mel MTP. The expression analysis showed that autophagy involvement in TMZ enhanced cytotoxicity. Furthermore, LY294002, an early-stage autophagy, and PI3K inhibitor were found to exert similar effects. Both chloroquine and LY294002 improved the cytotoxic effect of TMZ treatment, making this combination applicable as a potent antitumor treatment for metastatic melanoma.

PIK3CA hotspot mutations differentially impact responses to MET targeting in MET-driven and non-driven preclinical cancer models

Background

The MET receptor tyrosine kinase represents a promising target in cancer. PIK3CA activating mutations are common in several tumor types and can potentially confer resistance to anti-receptor tyrosine kinase therapy.

Methods

MET and/or PI3K pathway inhibition was assessed in NIH3T3 cells harboring MET-activating point mutation with or without ectopic expression of PIK3CA^E545K and PIK3CA^H1047R, as well as in MET-expressing head and neck cancer cells with endogenous PIK3CA mutations. Endpoints included PI3K pathway activation, cell proliferation, colony-forming ability, cell death, wound-healing, and an in vivo model.

Results

PIK3CA^E545K and PIK3CA^H1047R confer resistance to MET inhibition in MET-driven models. PIK3CA^H1047R was more potent than PIK3CA^E545K at inducing resistance in PI3K pathway activation, cell proliferation, colony-forming ability, induction of cell death and wound-healing upon MET inhibition. Resistance to MET inhibition could be synergistically overcome by co-targeting PI3K. Furthermore, combined MET/PI3K inhibition led to enhanced anti-tumor activity in vivo in tumors harboring PIK3CA^H1047R. In head and neck cancer cells the combination of MET/PI3K inhibitors led to more-than-additive effects.

Conclusions

PIK3CA mutations can lead to resistance to MET inhibition, supporting future clinical evaluation of combinations of PI3K and MET inhibitors in common scenarios of malignant neoplasms featuring aberrant MET expression and PIK3CA mutations.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-017-0660-5) contains supplementary material, which is available to authorized users.

Antitumor Efficacy of SLPI Promoter-Controlled Expression of Artificial microRNA Targeting EGFR in a Squamous Cell Carcinoma Cell Line

The purpose of this study was to develop a recombinant adenovirus with secretory leukoprotease inhibitor (SLPI) promoter-controlled expression for gene therapy of squamous cell carcinoma (SCC). An artificial microRNA targeting epidermal growth factor receptor (EGFR) was designed, and used to construct a replication-defective recombinant adenovirus with SLPI promoter-controlled expression. The silencing efficiency of this vector (Ad-SLPI-EGFRamiR) was detected in Hep-2 cells. Western blotting showed that the expression of 170 kD EGFR was significantly reduced in Hep-2 cells 72 h after infection with Ad-SLPI-EGFRamiR. At a multiplicity of infection (MOI) of 200 pfu/cell, proliferation of Hep-2 cells was highly inhibited by Ad-SLPI-EGFRamiR (inhibition rate: ~70%). The apoptosis rate of Hep-2 cells at 72 h after infection with Ad-SLPI-EGFRamiR at a MOI 35 pfu/cell was 32.8%. The adenovirus constructed was able to specifically inhibit the growth of SCC cells in vitro.

Targeted Therapy of Head and Neck Cancer

Head and neck squamous cell carcinoma (HNSCC) is one of the most common solid cancers worldwide. It is mainly caused by exposure to tobacco smoke and alcohol as well as infection with the human papilloma virus (HPV). The prognosis is poor, especially once it recurs or metastasizes. Current therapeutic options include surgery, radio- and chemotherapy. Epidermal growth factor receptor (EGFR) inhibitors are so far the only targeted agents that have been approved in head and neck cancer. Primary or secondary resistance is frequent or will eventually develop. Several driver mutations and other genomic aberrations have been described in HNSCC including EGFR overexpression and amplification. Yet, no predictive biomarkers for the application of EGFR inhibitors have been identified. Further targeted agents are in development for HNSCC, of which inhibitors of the PI3K pathway are the closest to clinical application. In recent years, the incidence of HPV-driven HNSCC has risen in Western countries. HPV-positive and -negative HNSCC are distinct molecular tumor entities, and consequences for targeted therapies have been discussed. This review looks at approved and investigational targeted treatment strategies as well as potential predictive biomarkers such as the HPV status to guide treatment.

Genomic Correlate of Exceptional Erlotinib Response in Head and Neck Squamous Cell Carcinoma

IMPORTANCE

Randomized clinical trials demonstrate no benefit for epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors in unselected patients with head and neck squamous cell carcinoma (HNSCC). However, a patient with stage IVA HNSCC received 13 days of neoadjuvant erlotinib and experienced a near-complete histologic response.

OBJECTIVE

To determine a mechanism of exceptional response to erlotinib therapy in HNSCC.

DESIGN, SETTING, AND PARTICIPANTS

Single patient with locally advanced HNSCC who received erlotinib monotherapy in a window-of-opportunity clinical trial (patients scheduled to undergo primary cancer surgery are treated briefly with an investigational agent). Whole-exome sequencing of pretreatment tumor and germline patient samples was performed at a quaternary care academic medical center, and a candidate somatic variant was experimentally investigated for mediating erlotinib response.

INTERVENTION

A brief course of erlotinib monotherapy followed by surgical resection.

MAIN OUTCOMES AND MEASURES

Identification of pretreatment tumor somatic alterations that may contribute to the exceptional response to erlotinib. Hypotheses were formulated regarding enhanced erlotinib response in preclinical models harboring the patient tumor somatic variant MAPK1 E322K following the identification of tumor somatic variants.

RESULTS

No EGFR alterations were observed in the pretreatment tumor DNA. Paradoxically, the tumor harbored an activating MAPK1 E322K mutation (allelic fraction 0.13), which predicts ERK activation and erlotinib resistance in EGFR-mutant lung cancer. The HNSCC cells with MAPK1 E322K exhibited enhanced EGFR phosphorylation and erlotinib sensitivity compared with wild-type MAPK1 cells.

CONCLUSIONS AND RELEVANCE

Selective erlotinib use in HNSCC may be informed by precision oncology approaches.

Exceptional response to cetuximab monotherapy in a patient with metastatic oropharyngeal squamous cell carcinoma: a molecular insight

Background

Metastatic head and neck squamous cell carcinoma (HNSCC) carries a very poor prognosis. A better understanding of the molecular driver of the disease and the identification of biomarkers of response remain paramount for an effective personalized therapy.

Case report

We report an original case of a 56-year-old patient diagnosed with metastatic HNSCC to both kidneys, who experienced a long-lasting complete response to a single-agent cetuximab, a monoclonal antibody-targeting EGFR. Comprehensive multiplatform biomarker analysis of the tumor revealed the presence of phosphatidyl-inositol 3 kinase mutation, EGFR overexpression, and the absence of PD-1/PD-L1 expression. Since PI3K, a downstream effector of EGFR, is activated, the tumor regression may have occurred mainly through a cetuximab-induced immune-mediated response, rather than EGFR signal blockade. It is plausible that this effect was enhanced by the lack of PD-1 and PD-L1 expression.

Conclusion

Our case proposes that the absence of PD-1 and PD-L1 expression in conjunction with EGFR overexpression may correlate with better response to cetuximab in HNSCC. This hypothesis needs to be examined through a large clinical trial.

Gene of the month: PIK3CA

PIK3CA encodes the p110α catalytic subunit of phosphatidylinositol 3-kinase (PI3K) which through its role in the PI3K/Akt pathway is important for the regulation of important cellular functions such as proliferation, metabolism and protein synthesis, angiogenesis and apoptosis. Mutations in PIK3CA are known to be involved in a wide range of human cancers and mutant PIK3CA is thought to act as an oncogene. The specific PIK3CA inhibitor, NVP-BYL719, has displayed promising results in cancer therapy and is currently under clinical trials. Furthermore, PI3K regulates autophagy, a cellular process that recycles proteins and organelles through lysosomal degradation and has recently been recognised as an attractive therapeutic target due to its pro- and anti-cancer properties. Several studies have attempted to investigate the effects of combining the inhibition of both PI3K and autophagy in cancer therapy, and an in vivo model has demonstrated that the combined use of a concomitant PI3K and autophagy inhibitor induced apoptosis in glioma cells.

Phase II clinical and exploratory biomarker study of dacomitinib in patients with recurrent and/or metastatic squamous cell carcinoma of head and neck

PURPOSE

The goals of this study were to investigate the clinical activity, safety, and biomarkers of dacomitinib, an irreversible tyrosine kinase inhibitor of EGFR, HER2, and HER4, in recurrent and/or metastatic squamous cell carcinoma of the head and neck (R/M-SCCHN).

EXPERIMENTAL DESIGN

Patients were eligible if the diseases were not amenable to curative treatment and had progressed on platinum-based chemotherapy, and were treated with dacomitinib 45 mg/day. The primary endpoint was objective response rate by RECISTv1.1. Exploratory analysis included the characterization of somatic mutation, gene copy number, gene expression, p16(INK4A) expression by IHC, and investigation of their relationship with clinical outcomes.

RESULTS

Forty-eight patients were evaluable for efficacy and toxicity. Ten patients (20.8%) had partial responses and 31 patients (65%) had stable diseases. The median progression-free survival (PFS) and overall survival (OS) were 3.9 months [95% confidence interval (CI), 2.9-5.0] and 6.6 months (95% CI, 5.4-10.3). Adverse events were mostly grade 1-2. Mutations in the PI3K pathway (PIK3CA, PTEN) and high expression of inflammatory cytokines (IL6, IL8, IL1A, IL1B, IL4, and TNF) were significantly associated with shorter PFS (2.9 vs. 4.9 months without mutations, P = 0.013; 2.8 vs. 9.9 months with low expression, P = 0.004). Those harboring PI3K pathway mutations or high inflammatory cytokine expression had shorter median OS (6.1 vs. 12.5 months lacking PI3K pathway mutations and with low inflammatory cytokine expression, P = 0.005).

CONCLUSIONS

Dacomitinib demonstrated clinical efficacy with manageable toxicity in platinum-failed R/M-SCCHN patients. Screening of PI3K pathway mutation and inflammatory cytokine expression may help identify which R/M-SCCHN patients are likely to gain benefit from dacomitinib.

Novel treatments for head and neck squamous cell carcinoma: preclinical identification and clinical investigation

Head and neck squamous cell carcinoma (HNSCC) is a common cancer worldwide. Classically, it is a disease related to tobacco and alcohol use; an increasing number of patients are being diagnosed with HNSCC caused by infection with the human papillomavirus. New deep-sequencing techniques have confirmed the importance of p53 and EGF receptor in HNSCC development, and have identified pathways of critical importance, such as PI3K/mTOR and NOTCH. Increasing knowledge of key molecular features has lead to new therapeutic avenues for HNSCC. Novel therapies under investigation in HNSCC include antibody and small molecule inhibitors of EGF receptor and its family members, PI3K inhibitors, antiangiogenic agents, immunotherapies and agents interacting with early developmental pathways such as Hedgehog.

Afatinib efficacy against squamous cell carcinoma of the head and neck cell lines in vitro and in vivo

Epidermal growth factor receptor (EGFR) inhibitors have demonstrated efficacy in squamous cell carcinoma of the head and neck (SCCHN). In addition to EGFR, other ErbB family members are expressed and activated in SCCHN. Afatinib is an ErbB family blocker that has been approved for treating patients with EGFR-mutated nonsmall cell lung cancer. We sought to determine the efficacy of afatinib in preclinical models and compare this to other EGFR-targeted agents. Afatinib efficacy was characterized in a panel of ten SCCHN cell lines and found to be most effective against cell lines amplified for EGFR. Afatinib had lower IC(50) values than did gefitinib against the same panel. Two EGFR-amplified cell lines that are resistant to gefitinib are sensitive to afatinib. Cetuximab was not found to have a synergistic effect with afatinib either in vitro or in vivo. Both afatinib and cetuximab were effective in tumor xenograft model. Afatinib is an effective agent in SCCHN especially in models with EGFR amplification.

Cytogenetic alterations and their molecular genetic correlates in head and neck squamous cell carcinoma: a next generation window to the biology of disease

Cytogenetic alterations underlie the development of head and neck squamous cell carcinoma (HNSCC), whether tobacco and alcohol use, betel nut chewing, snuff or human papillomavirus (HPV) causes the disease. Many of the molecular genetic aberrations in HNSCC result from these cytogenetic alterations. This review presents a brief introduction to the epidemiology of HNSCC, and discusses the role of HPV in the disease, cytogenetic alterations and their frequencies in HNSCC, their molecular genetic and The Cancer Genome Atlas (TCGA) correlates, prognostic implications, and possible therapeutic considerations. The most frequent cytogenetic alterations in HNSCC are gains of 5p14-15, 8q11-12, and 20q12-13, gains or amplifications of 3q26, 7p11, 8q24, and 11q13, and losses of 3p, 4q35, 5q12, 8p23, 9p21-24, 11q14-23, 13q12-14, 18q23, and 21q22. To understand their effects on tumor cell biology and response to therapy, the cytogenetic findings in HNSCC are increasingly being examined in the context of the biochemical pathways they disrupt. The goal is to minimize morbidity and mortality from HNSCC using cytogenetic abnormalities to identify valuable diagnostic biomarkers for HNSCC, prognostic biomarkers of tumor behavior, recurrence risk, and outcome, and predictive biomarkers of therapeutic response to identify the most efficacious treatment for each individual patient's tumor, all based on a detailed understanding of the next generation biology of HNSCC.

mTOR co-targeting in cetuximab resistance in head and neck cancers harboring PIK3CA and RAS mutations

Background

Cetuximab, a monoclonal blocking antibody against the epidermal growth factor receptor EGFR, has been approved for the treatment of squamous cell carcinomas of the head and neck (HNSCC). However, only few patients display long-term responses, prompting the search for cetuximab resistance mechanisms and new therapeutic options enhancing cetuximab effectiveness.

Methods

Cetuximab-sensitive HNSCC cells were retro-engineered to express PIK3CA and RAS oncogenes. These cells and HNSCC cells harboring endogenous PIK3CA and RAS oncogenes were xenografted into mice (n = 10 per group) and studied for their biochemical, antitumor, antiangiogenic, and antilymphangiogenic responses to cetuximab and mTOR targeting agents. All P values are two-sided.

Results

Cetuximab treatment of PIK3CA- and RAS-expressing HNSCC xenografts promoted an initial antitumor response, but all tumors relapsed within few weeks. In these tumors, cetuximab did not decrease the activity of mTOR, a downstream signaling target of EGFR, PIK3CA, and RAS. The combined administration of cetuximab and mTOR inhibitors exerted a remarkably increased antitumor activity, particularly in HNSCC cells that are resistant to cetuximab as a single agent. Indeed, cotargeting mTOR together with cetuximab caused a rapid tumor collapse of both PIK3CA- and RAS-expressing HNSCC xenografts (P < .001), concomitant with reduced proliferation (P < .001) and lymphangiogenesis (P < .001).

Conclusion

The presence of PIK3CA and RAS mutations and other alterations affecting the mTOR pathway activity in HNSCC could be exploited to predict the potential resistance to cetuximab, and to select the patients that may benefit the most from the concomitant administration of cetuximab and PI3K and/or mTOR inhibitors as a precision molecular therapeutic option for HNSCC patients.

An open-label single-arm, phase II trial of zalutumumab, a human monoclonal anti-EGFR antibody, in patients with platinum-refractory squamous cell carcinoma of the head and neck

PURPOSE

Treatment options for patients with platinum-refractory recurrent or metastatic squamous cell carcinoma of the head and neck (R/M SCCHN) are limited. The purpose of this study was to assess the efficacy and safety of zalutumumab in platinum-refractory R/M SCCHN.

METHODS

Patients with platinum-refractory R/M SCCHN were enrolled if they had performance status of 0-2, age ≥18 years and adequate organ function. Patients received weekly infusions of zalutumumab individually titrated to a grade 2 skin rash. Primary objective was overall survival (OS), and secondary objectives were efficacy and safety. A subgroup analysis of OS and progression-free survival (PFS) was conducted for various demographic, disease-related and molecular factors.

RESULTS

Ninety patients were enrolled. Twenty-three percent of patients had performance status (PS) 2 and 74 % had distant metastases. Median OS was 5.3 months (95 % CI [4.1, 7.1]), and median PFS was 2.1 months (95 % CI [2.0, 2.6]). Subgroup analysis by ECOG PS revealed median OS of 6.3 months for PS = 0-1 and 2.5 months for PS = 2. Objective response rate was 5.7 %, and disease control rate was 39.8 %. Grade 3-4 adverse events related to zalutumumab were observed in 19 % of patients and included skin rash (5 %), hypomagnesemia (4 %) and pneumonitis (1 %). The frequency of all-cause grade 3-4 AEs was 62 % and included infections (14 %), gastrointestinal disorders (12 %) and hypokalemia (6 %). Two deaths were deemed related to zalutumumab [ClinicalTrials.gov Identifier: NCT00542308].

CONCLUSIONS

Zalutumumab showed reasonable efficacy in platinum-refractory R/M SCCHN patients, and dose titration based on skin rash evaluation was feasible.

p70S6 kinase is a critical node that integrates HER-family and PI3 kinase signaling networks

Therapies targeting oncogenic drivers rapidly induce compensatory adaptive responses that blunt drug effectiveness, contributing to therapeutic resistance. Adaptive responses are characteristic of robust cell signaling networks, and thus there is increasing interest in drug combinations that co-target the driver and the adaptive response. An alternative approach to co-inhibiting oncogenic and adaptive targets is to identify a critical node where the activities of these targets converge. Nodes of convergence between signaling modules represent potential therapeutic vulnerabilities because their inhibition could result in the collapse of the network, leading to enhanced cytotoxicity. In this report we demonstrate that p70S6 kinase (p70S6K) can function as a critical node linking HER-family and phosphoinositide-3-kinase (PI3K) pathway signaling. We used high-throughput combinatorial drug screening to identify adaptive survival responses to targeted therapies, and found that HER-family and PI3K represented compensatory signaling pathways. Co-targeting these pathways with drug combinations caused synergistic cytotoxicity in cases where inhibition of neither target was effective as a monotherapy. We utilized Reverse Phase Protein Arrays and determined that phosphorylation of ribosomal protein S6 was synergistically down-regulated upon HER-family and PI3K/mammalian target of rapamycin (mTOR) co-inhibition. Expression of constitutively active p70S6K protected against apoptosis induced by combined HER-family and PI3K/mTOR inhibition. Direct inhibition of p70S6K with small molecule inhibitors phenocopied HER-family and PI3K/mTOR co-inhibition. These data implicate p70S6K as a critical node in the HER-family/PI3K signaling network. The ability of direct inhibitors of p70S6K to phenocopy co-inhibition of two upstream signaling targets indicates that identification and targeting of critical nodes can overcome adaptive resistance to targeted therapies.

p62/SQSTM1 accumulation in squamous cell carcinoma of head and neck predicts sensitivity to phosphatidylinositol 3-kinase pathway inhibitors

The phosphoinositol-3 kinase (PI3K) pathway is highly dysregulated in squamous cell carcinoma of the head and neck (SCCHN). While inhibitors of the PI3K/AKT pathway are being developed in cancer, their efficacy does not appear to be related to the presence of mutations or amplification in pathway genes. The PI3K pathway is a major regulator of macro-autophagy, an evolutionarily conserved catabolic process that degrades cellular materials to promote cellular homeostasis and survival under stress. Employing a panel of SCCHN cell lines, we observed a significant correlation between the activity of PI3K/AKT inhibitors and their ability to induce autophagy. More specifically, resistance to these inhibitors was associated with accumulation of p62/SQSTM1, a pleotropic protein that is consumed during autophagy, while loss of autophagy was, for the first time, found to be due to silencing of an essential autophagy gene, ATG7. Moreover, modulating ATG7 and p62/SQSTM1 could regulate sensitivity to PI3K/AKT inhibitors, underscoring a mechanistic link between autophagy and drug sensitivity. Analysis of human tissues revealed progressive accumulation of p62/SQSTM1 in a significant proportion of cancer samples compared to normal tissue, suggesting that defective autophagy has relevance to SCCHN. These findings are further validated by analysis of TCGA data confirming homozygous deletion and mRNA down-regulation of ATG7 in 10.0% of SCCHN samples. Taken together, these data indicate that p62/SQSTM1 levels modulate sensitivity to PI3K/AKT inhibitors; cancers vary in their capacity to undergo autophagy through epigenetic modification and, when deficient, accumulate p62/SQSTM1; and expression of autophagy-related proteins may serve as markers for resistance to PI3K/AKT inhibitors in SCCHN.

What is the best treatment for patients with human papillomavirus-positive and -negative oropharyngeal cancer?

The discovery that the human papilloma virus (HPV) is associated with a high and increasing percentage of oropharyngeal squamous cell carcinomas (SCCs) is among the most significant advances in the field of head and neck oncology. HPV-positive oropharyngeal cancer (HPVOPC) has clinical, etiologic, pathologic, and molecular features that distinguish it from HPV-negative disease. Increasingly, HPVOPC is being diagnosed in clinical practice because of the easy availability of p16 immunohistochemistry, a surrogate marker of HPV. The superior prognosis of HPVOPC has led to a reexamination of treatment approaches, and clinical trials are currently investigating strategies to deintensify treatment to reduce acute and late toxicity while preserving efficacy. This is of particular interest in low-risk patients. Unfortunately, patients with HPV-negative tumors still have high rates of locoregional failure and more efficacious treatments are required. This review of oropharyngeal SCC focuses on current and investigational treatment strategies in patients with both HPV-positive and HPV-negative oropharyngeal SCC.

Axl mediates acquired resistance of head and neck cancer cells to the epidermal growth factor receptor inhibitor erlotinib

Elevated expression and activity of the epidermal growth factor receptor (EGFR) is associated with development and progression of head and neck cancer (HNC) and a poor prognosis. Clinical trials with EGFR tyrosine kinase inhibitors (e.g., erlotinib) have been disappointing in HNC. To investigate the mechanisms mediating resistance to these agents, we developed an HNC cell line (HN5-ER) with acquired erlotinib resistance. In contrast to parental HN5 HNC cells, HN5-ER cells exhibited an epithelial-mesenchymal (EMT) phenotype with increased migratory potential, reduced E-cadherin and epithelial-associated microRNAs (miRNA), and elevated vimentin expression. Phosphorylated receptor tyrosine kinase profiling identified Axl activation in HN5-ER cells. Growth and migration of HN5-ER cells were blocked with a specific Axl inhibitor, R428, and R428 resensitized HN5-ER cells to erlotinib. Microarray analysis of HN5-ER cells confirmed the EMT phenotype associated with acquired erlotinib resistance, and identified activation of gene expression associated with cell migration and inflammation pathways. Moreover, increased expression and secretion of interleukin (IL)-6 and IL-8 in HN5-ER cells suggested a role for inflammatory cytokine signaling in EMT and erlotinib resistance. Expression of the tumor suppressor miR-34a was reduced in HN5-ER cells and increasing its expression abrogated Axl expression and reversed erlotinib resistance. Finally, analysis of 302 HNC patients revealed that high tumor Axl mRNA expression was associated with poorer survival (HR = 1.66, P = 0.007). In summary, our results identify Axl as a key mediator of acquired erlotinib resistance in HNC and suggest that therapeutic inhibition of Axl by small molecule drugs or specific miRNAs might overcome anti-EGFR therapy resistance.

Overcoming cancer cell resistance to VSV oncolysis with JAK1/2 inhibitors

Oncolytic vesicular stomatitis virus (VSV) has potent antitumor activity but some cancer cells are resistant to VSV killing, either constitutively or due to type I interferon (IFN) inducing an antiviral state in the cells. Here, we evaluated VSV oncolysis of a panel of human head and neck cancer cells and showed that VSV resistance in SCC25 and SCC15 cells could be reversed with Janus kinase (JAK) 1/2 inhibitors (JAK inhibitor I and ruxolitinib). Pre-treatment of cells with JAK1/2 inhibitors before or in conjunction with VSV enhanced viral infection, spread and progeny yield (100- to 1000-fold increase). In contrast, inhibitors of histone deacetylase (LBH589), phosphatidylinositol 3-kinase (GDC-0941, LY294002), mammalian target of rapamycin (rapamycin) or signal transducer and activator of transcription 3 (STAT3 inhibitor VII) were ineffective. Compared with VSV-sensitive SW579 cells, IFNα/β responsive antiviral genes (IRF-9, IRF-7, OAS1 but not MxA) are constitutively expressed in SCC25 cells. Pretreatment with JAK inhibitors reduced mRNA levels of these genes, increasing VSV expression in the cells. Interestingly, 1 h of drug exposure was sufficient to reverse SCC25 resistance to VSV and was still effective if virus was added 24 h later. Overall, we show here that JAK inhibitor I and ruxolitinib (Jakafi) can reverse resistance to VSV, supporting the rationale to incorporate JAK1/2 inhibitors in future VSV virotherapy trials.

Molecular phenotype predicts sensitivity of squamous cell carcinoma of the head and neck to epidermal growth factor receptor inhibition

Despite nearly universal expression of the wild-type epidermal growth factor receptor (EGFR) and reproducible activity of EGFR inhibitors in patients with squamous cell carcinoma of the head and neck (SCCHN), the majority of patients will not have objective responses. The mechanisms of this intrinsic resistance are not well established. We hypothesized that sensitivity to EGFR inhibitors can be predicted based on the inhibitors' effects on downstream signaling. Cell viability assays were used to assess sensitivity to the EGFR inhibitor gefitinib (ZD1839) in 8 SCCHN cell lines. Fluorescence in-situ hybridization showed the two most sensitive lines to be highly gene-amplified for EGFR. Western blotting confirmed that phosphoEGFR was inhibited at low concentrations of gefitinib in all lines tested. Phosphorylation of downstream signaling protein AKT was inhibited in sensitive lines while inhibition of phosphoERK displayed no relationship to gefitinib efficacy. Phosphatase and tensin homolog (PTEN) expression was evident in all cell lines. Activating PIK3CA mutations were found in two resistant cell lines where pAKT was not inhibited by gefitinib. In resistant cell lines harboring PIK3CA mutations, a PI3K inhibitor, LY294002, or AKT siRNA reduced cell viability with an additive effect demonstrated in combination with gefitinib. Additionally, LY294002 alone and in combination with gefitinib, was effective at treating PIK3CA mutated tumors xenografted into nude mice. Taken together this suggests that constitutively active AKT is a mechanism of intrinsic gefitinib resistance in SCCHN. This resistance can be overcome through targeting of the PI3K/AKT pathway in combination with EGFR inhibition.