Immunotherapy for Head and Neck Squamous Cell Carcinoma: Present and Future Approaches and Challenges.

Despite significant progress and improving outcomes in the management of head and neck squamous cell carcinoma (HNSCC), there are few effective treatment options for patients with recurrent or metastatic head and neck squamous cell carcinoma. The advent of immune checkpoint inhibitors has changed the treatment algorithm of head and neck squamous cell carcinoma and are approved in the frontline setting for recurrent and metastatic (R/M) head and neck squamous cell carcinomas. Although promising for some patients, most patients with R/M HNSCC do not derive clinical benefit from currently approved checkpoint inhibitors. Many studies are underway to identify the patient population that would benefit the most from immunotherapy as well as postimmunotherapy treatment failures, including novel combinations of immunomodulatory therapies. In this review, we summarize the clinical development of all major clinical trials of immunotherapy in HNSCC.

Circulating Tumor DNA Profiling in Liver Transplant for Hepatocellular Carcinoma, Cholangiocarcinoma, and Colorectal Liver Metastases: A Programmatic Proof of Concept.

INTRODUCTION: Circulating tumor DNA (ctDNA) is emerging as a promising, non-invasive diagnostic and surveillance biomarker in solid organ malignancy. However, its utility before and after liver transplant (LT) for patients with primary and secondary liver cancers is still underexplored. METHODS: Patients undergoing LT for hepatocellular carcinoma (HCC), cholangiocarcinoma (CCA), and colorectal liver metastases (CRLM) with ctDNA testing were included. CtDNA testing was conducted pre-transplant, post-transplant, or both (sequential) from 11/2019 to 09/2023 using Guardant360, Guardant Reveal, and Guardant360 CDx. RESULTS: 21 patients with HCC (n = 9, 43%), CRLM (n = 8, 38%), CCA (n = 3, 14%), and mixed HCC/CCA (n = 1, 5%) were included in the study. The median follow-up time was 15 months (range: 1-124). The median time from pre-operative testing to surgery was 3 months (IQR: 1-4; range: 0-5), and from surgery to post-operative testing, it was 9 months (IQR: 2-22; range: 0.4-112). A total of 13 (62%) patients had pre-transplant testing, with 8 (62%) having ctDNA detected (ctDNA+) and 5 (32%) not having ctDNA detected (ctDNA-). A total of 18 (86%) patients had post-transplant testing, 11 (61%) of whom were ctDNA+ and 7 (33%) of whom were ctDNA-. The absolute recurrence rates were 50% (n = 5) in those who were ctDNA+ vs. 25% (n = 1) in those who were ctDNA- in the post-transplant setting, though this difference was not statistically significant (p = 0.367). Six (29%) patients (HCC = 3, CCA = 1, CRLM = 2) experienced recurrence with a median recurrence-free survival of 14 (IQR: 6-40) months. Four of these patients had positive post-transplant ctDNA collected following diagnosis of recurrence, while one patient had positive post-transplant ctDNA collected preceding recurrence. A total of 10 (48%) patients had sequential ctDNA testing, of whom n = 5 (50%) achieved ctDNA clearance (+/-). The remainder were ctDNA+/+ (n = 3, 30%), ctDNA-/- (n = 1, 10%), and ctDNA-/+ (n = 1, 11%). Three (30%) patients showed the acquisition of new genomic alterations following transplant, all without recurrence. Overall, the median tumor mutation burden (TMB) decreased from 1.23 mut/Mb pre-transplant to 0.00 mut/Mb post-transplant. CONCLUSIONS: Patients with ctDNA positivity experienced recurrence at a higher rate than the ctDNA- patients, indicating the potential role of ctDNA in predicting recurrence after curative-intent transplant. Based on sequential testing, LT has the potential to clear ctDNA, demonstrating the capability of LT in the treatment of systemic disease. Transplant providers should be aware of the potential of donor-derived cell-free DNA and improved approaches are necessary to address such concerns.

Survival Outcomes of Advanced Thyroid Cancer Enriched in Brain Metastases Following Treatment With Small Molecule Inhibitors.

OBJECTIVE: Small molecule inhibitors (SMIs) are targeted therapies increasingly used in advanced thyroid carcinomas. This study aimed to evaluate the survival outcomes of thyroid cancer on SMI treatment, including in patients with brain metastases. METHODS: This retrospective study included patients with thyroid carcinomas who received at least one SMI between 2008 and 2022 at a tertiary level, academic institution. SMI included lenvatinib, sorafenib, dabrafenib-trametinib, selpercatinib, and cabozantinib. Patients were grouped by the presence of brain metastasis. Kaplan-Meier and log-rank tests modeled the overall survival (OS), defined from detection of first metastasis. RESULTS: In total, 116 patients (49.1% female, median age 61.1 years [IQR, 51.1-71.0]) were included. Thyroid cancer subtypes were: 57 (49.6%) papillary, 23 (19.8%) anaplastic, 23 (19.8%) medullary, and 13 (11.2%) follicular. There were 18 (15.5%) patients with brain metastases, and 98 (84.5%) with visceral metastases. Age, sex, thyroid subtype, SMI, and time to recurrence were not different between cohorts. OS was shorter in the brain metastasis cohort (31.7 vs 42.2 months, P =.44) and was not different after excluding anaplastic thyroid cancer (29.1 vs 62.3 months, P =.21). In the case of papillary thyroid cancer, patients with brain metastases trended toward worse OS (22.0 vs 59.9 months, P =.13). Nonanaplastic histology, total thyroidectomy (OR, 40.0; P <.001), number of unique therapies (OR, 10.9; P =.047), and mutation-directed therapy (OR, 24.7; P =.003) were associated with improved OS. CONCLUSION: This single-institutional analysis reports survival outcomes of 116 patients with advanced thyroid cancer on targeted therapies, including 18 patients with brain metastases. Mutation-directed therapy for BRAFV600E mutations, RET mutations, RET fusions, and NTRK fusions had superior survival.

Immunotherapy response in patients with cutaneous squamous cell carcinoma of head and neck with cranial nerve involvement.

BACKGROUND: Metastatic or locally advanced cutaneous squamous cell carcinoma (cSCC) can be treated with immunotherapy (IO). Cranial nerve involvement (CNI) is uncommon in cSCC and is a poor prognostic factor. Our aim is to describe how patients with CNI respond to IO monotherapy and/or as an adjunct to RT. METHODS: Under an IRB approved protocol, patients with histologically proven cSCC of the head and neck with CNI treated with IO were retrospectively reviewed. RESULTS: Twelve patients were included and received cemiplimab or pembrolizumab. Eight patients had CNI at diagnosis, and 4 at time of recurrence after non-IO therapy. Best responses were complete response (1), partial response (7), stable disease (1), progressive disease (2), and pending response (1). Nine patients are alive, 6 of which remain on IO. CONCLUSIONS: In this cohort, IO showed clinical response in 83% of patients, indicating IO can be an effective monotherapy, reserving RT for instances of local failure after IO.

Utilizing Dynamic Risk Stratification in Patients With Tall Cell Variant Papillary Thyroid Cancer.

OBJECTIVES: Tall cell variant (TCV) papillary thyroid cancer (PTC) is a subtype of PTC associated with aggressive tumor behavior, advanced stage, and higher rates of recurrence and mortality. The present study aimed to test an established dynamic risk stratification tool in the TCV population, with the goal of better predicting the postoperative course of these patients. STUDY DESIGN: Retrospective chart review. METHODS: A total of 94 patients with TCV who underwent total thyroidectomy with radioactive iodine ablation were retrospectively reviewed from 1998 through 2020. Biochemical, structural, and overall response to treatment was determined for each patient, based on postoperative thyroglobulin levels and imaging findings. Primary outcomes were locoregional and distant recurrence, presence of disease at final follow-up, need for additional intervention, and disease-specific mortality. RESULTS: Patients with TCV who were stratified as having an excellent overall response to treatment had lower rates of locoregional recurrence than indeterminate, biochemical incomplete, and structural incomplete responses (2.0%, 33.3%, 55.0%, and 85.7% at 5 years respectively, p < 0.001). The same was true for distant recurrence as well (2.0%, 9.0%, 35.1%, and 42.9%, p < 0.001). An excellent response was also associated with lower rates of presence of disease at final follow-up, need for additional intervention, and disease-specific mortality. CONCLUSIONS: Although TCV is an aggressive subtype associated with worse clinical outcomes than classical PTC, patients with an excellent overall response to treatment have significantly improved outcomes when compared to indeterminate, biochemical incomplete, and structural incomplete responses. LEVEL OF EVIDENCE: 3 Laryngoscope, 133:2430-2438, 2023.

Outcomes of responders to PD-1/PD-L1 inhibitors who discontinue therapy after sustained disease control.

BACKGROUND: PD-1/PD-L1 immune checkpoint inhibitors (ICIs) are widely used in the treatment of metastatic malignancies. Judiciously balancing disease control (DC) against development of immune-related adverse events (irAE) remains a crucial aspect of treatment. The effect of treatment discontinuation after sustained disease control (SDC) is unknown. The purpose of this analysis was to evaluate outcomes of responders to ICI who discontinue treatment after a minimum of 12 months (SDC). METHODS: We retrospectively reviewed the database of the University of New Mexico Comprehensive Cancer Center (UNMCCC) between 2014 and 2021 and identified patients who had received ICI. Patients with metastatic solid tumors who had stopped ICI therapy after achieving SDC [stable disease, partial response, complete response (SD, PR, CR)] were selected and outcomes reviewed from their electronic health records. RESULTS: We identified 204 patients who were treated with ICI for various solid cancers. Forty-four patients (21.6%) met the criteria, of whom 35 with follow-up data were included in the final analysis; including 11 melanoma, 5 non-small cell lung, 4 head & neck, 8 renal, 4 urothelial, 1 anal, 1 Merkel cell carcinoma, and 1 liposarcoma. Patients were divided into two groups: those who stopped ICI due to an irAE [irAE group, n = 14, median treatment time (MTT), 16.6 mo] and those who stopped due to other reasons (eg completion of 2 years of therapy, n = 20, non-cancer related surgery, n = 1) (non-irAE group, n = 21, MTT, 23.7 mo). Among the irAE group, the most common irAE included pneumonitis, rash, transaminitis, and fatigue. As of data cutoff date, 9 of 14 (64%) patients continued to show SDC. Only 5 of 14 (36%) patients in this group experienced progression of disease (PD), with 1 of 2 patients achieving DC (median follow-up of 19.2 mo after last dose of treatment, range 3-50.2 mo). Among the non-irAE group, 13 of 21 (62%) continued to have SDC. Eight of 21 (38%) experienced PD after stopping treatment, 7 of whom received ICI rechallenge, with 2 of 7 achieving DC (median follow-up of 22.2 mo, range 3.6-54.8 mo). At a median follow-up of 21.3 mo from stopping ICI therapy (range, 3-54.8 mo), 10 patients (71%) from the irAE group and 13 (61.9%) from the non-irAE group are in DC and have not experienced PD. CONCLUSIONS: We demonstrate that 22 (66%) patients experienced SDC, regardless of cancer type or development of irAE. After including patients who were re-challenged with ICI due to PD, 25 (71%) remain in DC. Future prospective malignancy-specific trials are warranted to evaluate optimal treatment duration.

Comparison of real-world outcomes following immunotherapy in recurrent or metastatic head and neck squamous cell carcinoma with outcomes of randomized controlled trials.

OBJECTIVES: Evaluate outcomes of patients with recurrent or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) treated with immunotherapy (IO). METHODS: Among patients with R/M HNSCC treated with IO in this retrospective single-institution cohort, Cox regression was used to compare overall survival (OS) for those with platinum-refractory disease and those treated in the first-line setting with OS from KEYNOTE-040/048, respectively. Multivariable Cox regression was used to identify predictors of OS. RESULTS: There was no significant OS difference for those treated in the platinum-refractory setting when compared to patients on KEYNOTE-040 (HR = 1.22, p = 0.27), nor for the first-line setting compared to KEYNOTE-048 (HR = 1.23, p = 0.19). ECOG-PS 1 (HR = 2.00, p = 0.02) and ECOG-PS 2 (HR = 3.13, p < 0.01) were associated with worse OS. Higher absolute lymphocyte count (ALC) was associated with improved OS (HR = 0.93 per 100 cells/µL, p = 0.03). CONCLUSIONS: Real-world outcomes of IO in R/M HNSCC are similar to outcomes in randomized control trials, with performance status and ALC correlating with OS.

Association of Treatment Strategies and Tumor Characteristics With Overall Survival Among Patients With Anaplastic Thyroid Cancer: A Single-Institution 21-Year Experience.

Importance: Survival outcomes for anaplastic thyroid cancer (ATC), the most aggressive subtype of thyroid cancers, have remained poor. However, targeted therapies and immunotherapies present new opportunities for treatment of this disease. Evaluations of survival outcomes over time with new multimodal therapies are needed for optimizing treatment plans. Objective: To evaluate the association of treatment strategies and tumor characteristics with overall survival (OS) among patients with ATC. Design, Setting, and Participants: This retrospective case series study evaluated the survival outcomes stratified by treatment strategies and tumor characteristics among patients with ATC treated at a tertiary level academic institution from January 1, 2000, to December 31, 2021. Demographic, tumor, treatment, and outcome characteristics were analyzed. Kaplan-Meier method and log rank test modeled OS by treatment type and tumor characteristics. Data were analyzed in May 2022. Main Outcomes and Measures: Overall survival (OS). Results: The study cohort comprised 97 patients with biopsy-proven ATC (median [range] age at diagnosis, 70 [38-93] years; 60 (62%) female and 85 [88%] White individuals; 59 [61%] never smokers). At ATC diagnosis, 18 (19%) patients had stage IVA, 19 (20%) had stage IVB, and 53 (55%) had stage IVC disease. BRAF status was assessed in 38 patients; 18 (47%) had BRAF-V600E variations and 20 (53%), BRAF wild type. Treatment during clinical course included surgery for 44 (45%) patients; chemotherapy, 41 (43%); definitive or adjuvant radiation therapy, 34 (RT; 35%); and targeted therapy, 28 (29%). Median OS for the total cohort was 6.5 (95% CI, 4.3-10.0) months. Inferior OS was found in patients who did not receive surgery (hazard ratio [HR], 2.12; 95% CI, 1.35-3.34; reference, received surgery), chemotherapy (HR, 3.28; 95% CI, 1.99-5.39; reference, received chemotherapy), and definitive or adjuvant RT (HR, 2.47; 95% CI, 1.52-4.02; reference, received definitive/adjuvant RT). On multivariable analysis, age at diagnosis (HR, 1.03; 95% CI, 1.01-1.06), tumor stage IVC (HR, 2.65; 95% CI, 1.35-5.18), and absence of definitive or adjuvant RT (HR, 1.90; 95% CI, 1.01-3.59) were associated with worse OS. Conclusions and Relevance: This retrospective single-institution study found that lower tumor stage, younger age, and the ability to receive definitive or adjuvant RT were associated with improved OS in patients with ATC.

Immunotherapy in HPV-Related Oropharyngeal Cancers.

OPINION STATEMENT: Human papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma (OPSCC) incidence has been increasing in recent decades. Treatment of the locally advanced HPV-related OPSCC includes a multidisciplinary approach. Immunotherapy with immune checkpoint inhibitors is used in the treatment of patients with recurrent/metastatic head and neck squamous cell carcinomas (HNSCC), including HPV-related OPSCC patients. There is increasing knowledge of the role of HPV in the tumor immune microenvironment. Therefore, HPV status of OPSCC plays an essential role in the design of immunotherapy clinical trials in both curative intent and metastatic settings. Moreover, HPV has become a potential therapeutic target, with vaccines and adoptive T-cell therapies being developed against HPV for the treatment of OPSCC. Several novel studies are designed to target HPV in combination with immune checkpoint inhibitors. Thus, HPV-related OPSCC remains a unique subgroup in the immunotherapy era.

Immunotherapy and Biomarker Testing in Recurrent and Metastatic Head and Neck Cancers: ASCO Guideline.

PURPOSE: To provide evidence-based recommendations for practicing physicians and other health care providers on immunotherapy and biomarker testing for head and neck cancers. METHODS: ASCO convened an Expert Panel of medical oncology, surgical oncology, radiation oncology, radiology, pathology, and patient advocacy experts to conduct a literature search, including systematic reviews, meta-analyses, randomized controlled trials, and prospective and retrospective comparative observational studies published from 2000 through 2022. Outcomes of interest included survival, overall response, and locoregional control. Expert Panel members used available evidence and informal consensus to develop evidence-based guideline recommendations. RESULTS: The literature search identified 28 relevant studies to inform the evidence base for this guideline. RECOMMENDATIONS: When possible, evidence-based recommendations were developed to address biomarker testing, first-line treatment regimens based on programmed death ligand-1 scores, immunotherapy in platinum-refractory recurrent or metastatic head and neck squamous cell carcinoma, immunotherapy in nasopharyngeal carcinoma, and radiation therapy in combination with immunotherapy for treatment of local recurrence.Additional information is available at www.asco.org/head-neck-cancer-guidelines.

Enhanced Vulnerability of LKB1-Deficient NSCLC to Disruption of ATP Pools and Redox Homeostasis by 8-Cl-Ado.

Loss-of-function somatic mutations of STK11, a tumor suppressor gene encoding LKB1 that contributes to the altered metabolic phenotype of cancer cells, is the second most common event in lung adenocarcinomas and often co-occurs with activating KRAS mutations. Tumor cells lacking LKB1 display an aggressive phenotype, with uncontrolled cell growth and higher energetic and redox stress due to its failure to balance ATP and NADPH levels in response to cellular stimulus. The identification of effective therapeutic regimens for patients with LKB1-deficient non-small cell lung cancer (NSCLC) remains a major clinical need. Here, we report that LKB1-deficient NSCLC tumor cells displayed reduced basal levels of ATP and to a lesser extent other nucleotides, and markedly enhanced sensitivity to 8-Cl-adenosine (8-Cl-Ado), an energy-depleting nucleoside analog. Treatment with 8-Cl-Ado depleted intracellular ATP levels, raised redox stress, and induced cell death leading to a compensatory suppression of mTOR signaling in LKB1-intact, but not LKB1-deficient, cells. Proteomic analysis revealed that the MAPK/MEK/ERK and PI3K/AKT pathways were activated in response to 8-Cl-Ado treatment and targeting these pathways enhanced the antitumor efficacy of 8-Cl-Ado. IMPLICATIONS: Together, our findings demonstrate that LKB1-deficient tumor cells are selectively sensitive to 8-Cl-Ado and suggest that therapeutic approaches targeting vulnerable energy stores combined with signaling pathway inhibitors merit further investigation for this patient population.

NRG-HN003: Phase I and Expansion Cohort Study of Adjuvant Pembrolizumab, Cisplatin and Radiation Therapy in Pathologically High-Risk Head and Neck Cancer.

The anti-PD1 monoclonal antibody pembrolizumab improves survival in recurrent/metastatic head and neck squamous cell carcinoma (HNSCC). Patients with locoregional, pathologically high-risk HNSCC recur frequently despite adjuvant cisplatin-radiation therapy (CRT). Targeting PD1 may reverse immunosuppression induced by HNSCC and CRT. We conducted a phase I trial with an expansion cohort (n = 20) to determine the recommended phase II schedule (RP2S) for adding fixed-dose pembrolizumab to standard adjuvant CRT. Eligible patients had resected HPV-negative, stage III-IV oral cavity, pharynx, or larynx HNSCC with extracapsular nodal extension or positive margin. RP2S was declared if three or fewer dose-limiting toxicities (DLT) occurred in a cohort of 12. DLT was defined as grade 3 or higher non-hematologic adverse event (AE) related to pembrolizumab, immune-related AE requiring over 2 weeks of systemic steroids, or unacceptable RT delay. A total of 34 patients enrolled at 23 NRG institutions. During the first cohort, only one DLT was observed (fever), thus RP2S was declared as pembrolizumab 200 mg every 3 weeks for eight doses, starting one week before CRT. During expansion, three additional DLTs were observed (wound infection, diverticulitis, nausea). Of the 34 patients, 28 (82%) received five or more doses of pembrolizumab. This regimen was safe and feasible in a cooperative group setting. Further development is warranted.

Role of molecular signature to differentiate second primary lung cancer from metastasis in a patient with squamous cell carcinoma of oral cavity.

BACKGROUND: Lung is the most common site of distant metastasis for patients with head and neck squamous cell carcinoma (HNSCC). However, differentiating second primary lung cancers from metastasis may be difficult for p16 negative HNSCC. CASE: We describe a case of oral cavity squamous cell carcinoma (SCC) who was found to have lung nodule and hilar lymphadenopathy (LAD) after surgery and radiation therapy. Hilar node was consistent with SCC however, it was difficult to differentiate second primary lung cancer and metastasis from oral cavity SCC. Next-generation sequencing was done for the primary oral cavity and the hilar node. Both samples had the same type of TP53 mutation and variants of unknown significance suggesting metastatic HNSCC. He was treated with a chemotherapy regimen for metastatic HNSCC. CONCLUSION: Molecular studies can help to differentiate metastasis from second primary lung cancers for p16 negative HNSCC.

MEK/ERK signaling is a critical regulator of high-risk human papillomavirus oncogene expression revealing therapeutic targets for HPV-induced tumors.

Intracellular pathogens have evolved to utilize normal cellular processes to complete their replicative cycles. Pathogens that interface with proliferative cell signaling pathways risk infections that can lead to cancers, but the factors that influence malignant outcomes are incompletely understood. Human papillomaviruses (HPVs) predominantly cause benign hyperplasia in stratifying epithelial tissues. However, a subset of carcinogenic or "high-risk" HPV (hr-HPV) genotypes are etiologically linked to nearly 5% of all human cancers. Progression of hr-HPV-induced lesions to malignancies is characterized by increased expression of the E6 and E7 oncogenes and the oncogenic functions of these viral proteins have been widely studied. Yet, the mechanisms that regulate hr-HPV oncogene transcription and suppress their expression in benign lesions remain poorly understood. Here, we demonstrate that EGFR/MEK/ERK signaling, influenced by epithelial contact inhibition and tissue differentiation cues, regulates hr-HPV oncogene expression. Using monolayer cells, epithelial organotypic tissue models, and neoplastic tissue biopsy materials, we show that cell-extrinsic activation of ERK overrides cellular control to promote HPV oncogene expression and the neoplastic phenotype. Our data suggest that HPVs are adapted to use the EGFR/MEK/ERK signaling pathway to regulate their productive replicative cycles. Mechanistic studies show that EGFR/MEK/ERK signaling influences AP-1 transcription factor activity and AP-1 factor knockdown reduces oncogene transcription. Furthermore, pharmacological inhibitors of EGFR, MEK, and ERK signaling quash HPV oncogene expression and the neoplastic phenotype, revealing a potential clinical strategy to suppress uncontrolled cell proliferation, reduce oncogene expression and treat HPV neoplasia.

Primary squamous cell carcinoma of thyroid with a novel BRAF mutation and High PDL-1 expression: A case report with treatment implications and review of literature.

Primary squamous cell carcinoma of thyroid (SCC-T) is an extremely rare, aggressive neoplasm with median survival of 9 months. Pure squamous morphology with absence of other cell types is required for diagnosis of SCC-T. Clinically, SCC-T behaves like anaplastic thyroid carcinoma (ATC) showing rapid growth, and extra thyroidal extension. We report a 91-year-old woman presenting with an enlarging thyroid mass and accompanying dysphagia and hoarseness. Fine needle aspiration revealed hypercellular specimen with large, pleomorphic, malignant cells. Intraoperative assessment revealed an inoperable tumor involving both thyroid lobes and extensively infiltrating surrounding soft tissues. A subtotal thyroidectomy was performed. Histology revealed squamous cell carcinoma replacing native thyroid tissue and infiltrating adjacent skeletal muscle. Lymphovascular and perineural invasion were present. Immunohistochemistry showed tumor cells positive for CK5-p40, Pax-8, TTF-1 and negative for thyroglobulin. P53 expression by IHC was high and Ki-67 proliferation index was > 90 %. (Next generation sequencing revealed a novel BRAF mutation (BRAF c.1799 T > A; 1801_1812del) along with TP53 and TERT mutations. PDL-1 immunohistochemistry showed positive expression in tumor cells (>80%), making patient also amenable to anti-PDL-1 immunotherapy. Patient was treated with BRAF inhibitor therapy with initial relief but eventually was put on hospice care due to increasing intolerance to therapy. This case represents a rare thyroid malignancy with a unique molecular signature consisting of a novel BRAF mutation [previously not described in SCC-T or ATC], associated with TERT-TP53 mutations. Further, importance of PDL-1 testing as a prognostic marker and as a guide to immunotherapy in refractory tumors is discussed.

PI3K blockage synergizes with PLK1 inhibition preventing endoreduplication and enhancing apoptosis in anaplastic thyroid cancer.

Anaplastic thyroid cancer (ATC) is among the most lethal malignancies. The mitotic kinase PLK1 is overexpressed in the majority of ATCs and PLK1 inhibitors have shown preclinical efficacy. However, they also cause mitotic slippage and endoreduplication, leading to the generation of tetraploid, genetically unstable cell populations. We hypothesized that PI3K activity may facilitate mitotic slippage upon PLK1 inhibition, and thus tested the effect of combining PLK1 and PI3K inhibitors in ATC models, in vitro and in vivo. Treatment with BI6727 and BKM120 resulted in a significant synergistic effect in ATC cells, independent of the levels of AKT activity. Combination of the two drugs enhanced growth suppression at doses for which the single drugs showed no effect, and led to a massive reduction of the tetraploid cells population. Furthermore, combined treatment in PI3Khigh cell lines showed a significant induction of apoptosis. Finally, combined inhibition of PI3K and PLK1 was extremely effective in vivo, in an immunocompetent allograft model of ATC. Our results demonstrate a clear therapeutic potential of combining PLK1 and PI3K inhibitors in anaplastic thyroid tumors.

Emerging treatment for advanced lung cancer with EGFR mutation.

INTRODUCTION: Lung cancer is the leading cause of cancer-related death worldwide. It is usually diagnosed at advanced stage for which platinum-based chemotherapy had been the standard approach, although with limited clinical benefits. Discovery of oncogenic EGFR mutations in lung cancer have shifted the treatment paradigm with molecularly targeted therapies. AREAS COVERED: EGFR tyrosine kinase inhibitors (TKIs) have become the first-line choice in patients with advanced NSCLC harboring EGFR activating mutations. However, resistance to targeted therapy develops inevitably during the course of treatment. Multiple mechanisms of acquired resistance have been discovered, most commonly the secondary mutation of T790M in exon 20. The second- and third-generation EGFR TKIs are holding promise to overcome T790M-associated acquired resistance and currently being tested in clinical trials. In this article, we focus on the emerging approaches to overcome the different mechanisms of resistance to targeted therapies in patients with EGFR-mutant advanced NSCLC. EXPERT OPINION: It is essential to uncover the complex mechanisms underlying the progression of lung cancer after upfront EGFR TKIs. Next generation, in particular, the third generations of EGFR TKIs have been developed against acquired T790M mutation with promising clinical activity and better toxicity profile. Combination of targeted therapies has also been explored. Further studies are needed to detect the real-time changes of the resistance mechanisms and to develop new therapeutic strategies for lung cancer patients with EGFR mutations.