MET Fusions in NSCLC: Clinicopathologic Features and Response to MET Inhibition.

INTRODUCTION: MET fusions have been described only rarely in NSCLC. Thus, data on patient characteristics and treatment response are limited. We here report histopathologic data, patient demographics, and treatment outcome including response to MET tyrosine kinase inhibitor (TKI) therapy in MET fusion-positive NSCLC. METHODS: Patients with NSCLC and MET fusions were identified mostly by RNA sequencing within the routine molecular screening program of the national Network Genomic Medicine, Germany. RESULTS: We describe a cohort of nine patients harboring MET fusions. Among these nine patients, two patients had been reported earlier. The overall frequency was 0.29% (95% confidence interval: 0.15-0.55). The tumors were exclusively adenocarcinoma. The cohort was heterogeneous in terms of age, sex, or smoking status. We saw five different fusion partner genes (KIF5B, TRIM4, ST7, PRKAR2B, and CAPZA2) and several different breakpoints. Four patients were treated with a MET TKI leading to two partial responses, one stable disease, and one progressive disease. One patient had a BRAF V600E mutation as acquired resistance mechanism. CONCLUSIONS: MET fusions are very rare oncogenic driver events in NSCLC and predominantly seem in adenocarcinomas. They are heterogeneous in terms of fusion partners and breakpoints. Patients with MET fusion can benefit from MET TKI therapy.

KEAP1/NFE2L2 Pathway Signature Outperforms KEAP1/NFE2L2 Mutation Status and Reveals Alternative Pathway-Activating Mutations in NSCLC.

INTRODUCTION: Activation of the antioxidant KEAP1/NFE2L2 (NRF2) pathway leads to increased glutamine dependence and an aggressive phenotype in NSCLC. Because this pathway has been explored as a clinical target, we developed a transcriptomic signature for identifying KEAP1/NFE2L2-activated tumors. METHODS: A total of 971 NSCLC samples were used to train an expression signature (K1N2-score) to predict KEAP1/NFE2L2 mutations. There were 348 in-house NSCLCs that were analyzed using a NanoString expression panel for validation. RESULTS: The 46-gene K1N2 score robustly predicted KEAP1/NFE2L2 mutations in the validation set irrespective of histology and mutation (area under the curve: 89.5, sensitivity: 90.2%), suggesting that approximately 90% of KEAP1/NFE2L2 mutations are pathway-activating. The K1N2-score outperformed KEAP1/NFE2L2 mutational status when predicting patient survival (score p = 0.047; mutation p = 0.215). In K1N2 score-positive but KEAP1/NFE2L2 wild-type samples, enrichment testing identified SMARCA4/BRG1 and CUL3 mutations as mimics of KEAP1/NFE2L2 mutations. CONCLUSIONS: The K1N2-score identified KEAP1/NFE2L2-activated NSCLC by robustly detecting KEAP1/NFE2L2mut cases and discovering alternative genomic activators. It is a potential means for selecting patients with a constitutively active KEAP1/NFE2L2 pathway.

Resistance to MET inhibition in MET-dependent NSCLC and therapeutic activity after switching from type I to type II MET inhibitors.

OBJECTIVES: Resistance to MET inhibition occurs inevitably in MET-dependent non-small cell lung cancer and the underlying mechanisms are insufficiently understood. We describe resistance mechanisms in patients with MET exon 14 skipping mutation (METΔex14), MET amplification, and MET fusion and report treatment outcomes after switching therapy from type I to type II MET inhibitors. MATERIALS AND METHODS: Pre- and post-treatment biopsies were analysed by NGS (next generation sequencing), digital droplet PCR (polymerase chain reaction), and FISH (fluorescense in situ hybridization). A patient-derived xenograft model was generated in one case. RESULTS: Of 26 patients with MET tyrosine kinase inhibitor treatment, eight had paired pre- and post-treatment biopsies (Three with MET amplification, three with METΔex14, two with MET fusions (KIF5B-MET and PRKAR2B-MET).) In six patients, mechanisms of resistance were detected, whereas in two cases, the cause of resistance remained unclear. We found off-target resistance mechanisms in four cases with KRAS mutations and HER2 amplifications appearing. Two patients exhibited second-site MET mutations (p.D1246N and p. Y1248H). Three patients received type I and type II MET tyrosine kinase inhibitors sequentially. In two cases, further progressive disease was seen hereafter. The patient with KIF5B-MET fusion received three different MET inhibitors and showed long-lasting stable disease and a repeated response after switching therapy, respectively. CONCLUSION: Resistance to MET inhibition is heterogeneous with on- and off-target mechanisms occurring regardless of the initial MET aberration. Switching therapy between different types of kinase inhibitors can lead to repeated responses in cases with second-site mutations. Controlled clinical trials in this setting with larger patient numbers are needed, as evidence to date is limited to preclinical data and case series.

Differentially expressed messenger RNA/proteins can distinguish teratoma from necrosis in postchemotherapy retroperitoneal lymph node dissection tissue.

BACKGROUND: Before postchemotherapy retroperitoneal lymph node dissection (pcRPLND), in patients with metastasized germ cell tumors (GCTs), those harboring necrosis (NEC) cannot be distinguished from those who have teratoma (TER), resulting in relevant overtreatment, whereas microRNA-371a-3p may be predictive for viable GCT. The purpose of this study was to explore messenger RNA (mRNA) and proteins to distinguish TER from NEC in pcRPLND tissue. METHODS: The discovery cohort consisted in total of 48 patients, including 16 each with TER, viable GCT, and NEC. Representative areas were microdissected. A NanoString panel and proteomics were used to analyze 770 genes and >5000 proteins. The most significantly and differentially expressed combination of both parameters, mRNA and its associated protein, between TER and NEC was validated using immunohistochemistry (IHC) in an independent validation cohort comprising 66 patients who were not part of the discovery cohort. RESULTS: The authors observed that anterior gradient protein 2 homolog (AGR2) and keratin, type I cytoskeletal 19 (KRT19) were significantly differentially expressed in TER versus NEC in mRNA and protein analyses (proteomics). The technical validation using IHC was successful in the same patients. These proteins were further validated by IHC in the independent patient cohort and exhibited significantly higher levels in TER versus NEC (p < .0001; area under the curve, 1.0; sensitivity and specificity, 100% each). CONCLUSIONS: The current study demonstrated that KRT19 and AGR2 mRNA and protein are overexpressed in TER versus NEC in pcRPLND tissue and might serve as a future diagnostic target to detect TER, for instance, by functional imaging, to avoid overtreatment. PLAIN LANGUAGE SUMMARY: The proteins and the corresponding genes called AGR2 and KRT19 can differentiate between teratoma and necrosis in remaining tumor masses after chemotherapy in patients who have metastasized testicular cancer. This may be a way to improve presurgical diagnostics and to reduce the current overtreatment of patients with necrosis only, who could be treated sufficiently by surveillance.

Proficiency testing of PIK3CA mutations in HR+/HER2-breast cancer on liquid biopsy and tissue.

Precision oncology based on specific molecular alterations requires precise and reliable detection of therapeutic targets in order to initiate the optimal treatment. In many European countries-including Germany-assays employed for this purpose are highly diverse and not prescribed by authorities, making inter-laboratory comparison difficult. To ensure reproducible molecular diagnostic results across many laboratories and different assays, ring trials are essential and a well-established tool. Here, we describe the design and results of the ring trial for the detection of therapeutically relevant PIK3CA hotspot mutations in HR+/HER2-breast cancer tissue and liquid biopsy (LB). For PIK3CA mutation detection in tissue samples, 43 of the 54 participants (80%) provided results compliant with the reference values. Participants using NGS-based assays showed higher success rate (82%) than those employing Sanger sequencing (57%). LB testing was performed with two reference materials differing in the length of the mutated DNA fragments. Most participants used NGS-based or commercial real-time PCR assays (70%). The 167 bp fragments led to a successful PIK3CA mutation detection by only 31% of participants whereas longer fragments of 490 bp were detectable even by non-optimal assays (83%). In conclusion, the first ring trial for PIK3CA mutation detection in Germany showed that PIK3CA mutation analysis is broadly established for tissue samples and that NGS-based tests seem to be more suitable than Sanger sequencing. PIK3CA mutation detection in LB should be carried out with assays specifically designed for this purpose in order to avoid false-negative results.

Transcriptome analysis reveals upregulation of immune response pathways at the invasive tumour front of metastatic seminoma germ cell tumours.

BACKGROUND: Testicular germ cell tumours (TGCTs) have a high metastasis rate. However, the mechanisms related to their invasion, progression and metastasis are unclear. Therefore, we investigated gene expression changes that might be linked to metastasis in seminomatous testicular germ cell tumour (STGCT) patients. METHODS: Defined areas [invasive tumour front (TF) and tumour centre (TC)] of non-metastatic (with surveillance and recurrence-free follow-up >2 years) and metastatic STGCTs were collected separately using laser capture microdissection. The expression of 760 genes related to tumour progression and metastasis was analysed using nCounter technology and validated with quantitative real-time PCR and enzyme-linked immunosorbent assay. RESULTS: Distinct gene expression patterns were observed in metastatic and non-metastatic seminomas with respect to both the TF and TC. Comprehensive pathway analysis showed enrichment of genes related to tumour functions such as inflammation, angiogenesis and metabolism at the TF compared to the TC. Remarkably, prominent inflammatory and cancer-related pathways, such as interleukin-6 (IL-6) signalling, integrin signalling and nuclear factor-κB signalling, were significantly upregulated in the TF of metastatic vs non-metastatic tumours. CONCLUSIONS: IL-6 signalling was the most significantly upregulated pathway in metastatic vs non-metastatic tumours and therefore could constitute a therapeutic target for future personalised therapy. In addition, this is the first study showing intra- and inter-tumour heterogeneity in STGCT.

Biomarkers for Homologous Recombination Deficiency in Cancer.

DNA double-strand breaks foster tumorigenesis and cell death. Two distinct mechanisms can be activated by the cell for DNA repair: the accurate mechanism of homologous recombination repair or the error-prone non-homologous end joining. Homologous Recombination Deficiency (HRD) is associated with sensitivity towards PARP inhibitors (PARPi) and its determination is used as a biomarker for therapy decision making. Nevertheless, the biology of HRD is rather complex and the application, as well as the benefit of the different HRD biomarker assays, is controversial. Acquiring knowledge of the underlying molecular mechanisms is the main prerequisite for integration of new biomarker tests. This study presents an overview of the major DNA repair mechanisms and defines the concepts of HRR, HRD and BRCAness. Moreover, currently available biomarker assays are described and discussed with respect to their application for routine clinical diagnostics. Since patient stratification for efficient PARP inhibitor therapy requires determination of the BRCA mutation status and genomic instability, both should be established comprehensively. For this purpose, a broad spectrum of distinct assays to determine such combined HRD scores is already available. Nevertheless, all tests require careful validation using clinical samples to meet the criteria for their establishment in clinical testing.

Cancer-specific immune evasion and substantial heterogeneity within cancer types provide evidence for personalized immunotherapy.

The immune response against cancer is orchestrated by various parameters and site-dependent specificities have been poorly investigated. In our analyses of ten different cancer types, we describe elevated infiltration by regulatory T cells as the most common feature, while other lymphocyte subsets and also expression of immune-regulatory molecules on tumor-infiltrating lymphocytes showed site-specific variation. Multiparametric analyses of these data identified similarities of renal and liver or lung with head and neck cancer. Co-expression of immune-inhibitory ligands on tumor cells was most frequent in colorectal, lung and ovarian cancer. Genes related to antigen presentation were frequently dysregulated in liver and lung cancer. Expression of co-inhibitory molecules on tumor-infiltrating T cells accumulated in advanced stages while T-cell abundance was related to enhanced expression of genes related to antigen presentation. Our results promote evaluation of cancer-specific or even personalized immunotherapeutic combinations to overcome primary or secondary resistance as major limitation of immune-checkpoint inhibition.

Detection of gene fusions using targeted next-generation sequencing: a comparative evaluation.

BACKGROUND: Gene fusions represent promising targets for cancer therapy in lung cancer. Reliable detection of multiple gene fusions is therefore essential. METHODS: Five commercially available parallel sequencing assays were evaluated for their ability to detect gene fusions in eight cell lines and 18 FFPE tissue samples carrying a variety of known gene fusions. Four RNA-based assays and one DNA-based assay were compared; two were hybrid capture-based, TruSight Tumor 170 Assay (Illumina) and SureSelect XT HS Custom Panel (Agilent), and three were amplicon-based, Archer FusionPlex Lung Panel (ArcherDX), QIAseq RNAscan Custom Panel (Qiagen) and Oncomine Focus Assay (Thermo Fisher Scientific). RESULTS: The Illumina assay detected all tested fusions and showed the smallest number of false positive results. Both, the ArcherDX and Qiagen panels missed only one fusion event. Among the RNA-based assays, the Qiagen panel had the highest number of false positive events. The Oncomine Focus Assay (Thermo Fisher Scientific) was the least adequate assay for our purposes, seven fusions were not covered by the assay and two fusions were classified as uncertain. The DNA-based SureSelect XT HS Custom Panel (Agilent) missed three fusions and nine fusions were only called by one software version. Additionally, many false positive fusions were observed. CONCLUSIONS: In summary, especially RNA-based parallel sequencing approaches are potent tools for reliable detection of targetable gene fusions in clinical diagnostics.

Prevalence and potential biological role of TERT amplifications in ALK translocated adenocarcinoma of the lung.

AIMS: The advent of specific ALK-targeting drugs has radically changed the outcome of patients with ALK translocated non-small-cell lung cancer (NSCLC). However, emerging resistance to treatment with ALK inhibitors in these patients remains a major concern. In previous studies, we analysed two ALK+ patient cohorts (TP53 wild-type/TP53 mutated) in terms of copy number alterations. All patients belonging to the TP53 wild-type group had mainly genetically stable genomes, with one exception showing chromosomal instability and amplifications of several gene loci, including TERT. Here, we aimed to determine the prevalence of TERT amplifications in these ALK+ lung cancer patients by analysing an independent cohort of 109 ALK translocated cases. We further analysed the copy numbers of numerous cancer-relevant genes and other genetic aberrations. METHODS AND RESULTS: The prevalence of TERT amplifications was determined by means of FISH analyses. Copy numbers of 87 cancer-relevant genes were determined by NanoString nCounter® technology, FoundationOne® and lung-specific NGS panels in some of these TERT-amplified samples, and clinical data on patients with TERT-amplified tumours were collected. Our data revealed that five (4.6%) of all 109 analysed ALK+ patients harboured amplification of TERT and that these patients had genetically unstable genomes. CONCLUSIONS: Our preliminary study shows that ALK+ adenocarcinomas should be evaluated in the context of their genomic background in order to more clearly understand and predict patients' individual course of disease.

Expression Profiling of Extracellular Matrix Genes Reveals Global and Entity-Specific Characteristics in Adenoid Cystic, Mucoepidermoid and Salivary Duct Carcinomas.

The composition of the extracellular matrix (ECM) plays a pivotal role in tumour initiation, metastasis and therapy resistance. Until now, the ECM composition of salivary gland carcinomas (SGC) has not been studied. We quantitatively analysed the mRNA of 28 ECM-related genes of 34 adenoid cystic (AdCy; n = 11), mucoepidermoid (MuEp; n = 14) and salivary duct carcinomas (SaDu; n = 9). An incremental overexpression of six collagens (including COL11A1) and four glycoproteins from MuEp and SaDu suggested a common ECM alteration. Conversely, AdCy and MuEp displayed a distinct overexpression of COL27A1 and LAMB3, respectively. Nonhierarchical clustering and principal component analysis revealed a more specific pattern for AdCy with low expression of the common gene signature. In situ studies at the RNA and protein level confirmed these results and indicated that, in contrast to MuEp and SaDu, ECM production in AdCy results from tumour cells and not from cancer-associated fibroblasts (CAFs). Our findings reveal different modes of ECM production leading to common and distinct RNA signatures in SGC. Of note, an overexpression of COL27A1, as in AdCy, has not been linked to any other neoplasm so far. Here, we contribute to the dissection of the ECM composition in SGC and identified a panel of deferentially expressed genes, which could be putative targets for SGC therapy and overcoming therapeutic resistance.

Predictive molecular pathology in the time of coronavirus disease (COVID-19) in Europe.

AIMS: Lung cancer predictive biomarker testing is essential to select advanced-stage patients for targeted treatments and should be carried out without delays even during health emergencies, such as the coronavirus (COVID-19) outbreak. METHODS: Fifteen molecular laboratories from seven different European countries compared 4 weeks of national lockdown to a corresponding period in 2019, in terms of tissue and/or plasma-based molecular test workload, analytical platforms adopted, number of cases undergoing programmed death-ligand1 (PD-L1) expression assessment and DNA-based molecular tests turnaround time. RESULTS: In most laboratories (80.0%), tissue-based molecular test workload was reduced. In 40.0% of laboratories (6/15), the decrease was >25%, and in one, reduction was as high as 80.0%. In this instance, a concomitant increase in liquid biopsy was reported (60.0%). Remarkably, in 33.3% of the laboratories, real-time PCR (RT-PCR)-based methodologies increased, whereas highly multiplexing assays approaches decreased. Most laboratories (88.9%) did not report significant variations in PD-L1 volume testing. CONCLUSIONS: The workload of molecular testing for patients with advanced-stage lung cancer during the lockdown showed little variations. Local strategies to overcome health emergency-related issues included the preference for RT-PCR tissue-based testing methodologies and, occasionally, for liquid biopsy.

Mutational spectrum of acquired resistance to reversible versus irreversible EGFR tyrosine kinase inhibitors.

BACKGROUND: Over the past years, EGFR tyrosine kinase inhibitors (TKI) revolutionized treatment response. 1st-generation (reversible) EGFR TKI and later the 2nd -generation irreversible EGFR TKI Afatinib were aimed to improve treatment response. Nevertheless, diverse resistance mechanisms develop within the first year of therapy. Here, we evaluate the prevalence of acquired resistance mechanisms towards reversible and irreversible EGFR TKI. METHODS: Rebiopsies of patients after progression to EGFR TKI therapy (> 6 months) were targeted to histological and molecular analysis. Multiplexed targeted sequencing (NGS) was conducted to identify acquired resistance mutations (e.g. EGFR p.T790M). Further, Fluorescence in situ hybridisation (FISH) was applied to investigate the status of bypass mechanisms like, MET or HER2 amplification. RESULTS: One hundred twenty-three rebiopsy samples of patients that underwent first-line EGFR TKI therapy (PFS ≥6 months) were histologically and molecularly profiled upon clinical progression. The EGFR p.T790M mutation is the major mechanism of acquired resistance in patients treated with reversible as well as irreversible EGFR TKI. Nevertheless a statistically significant difference for the acquisition of T790M mutation has been identified: 45% of afatinib- vs 65% of reversible EGFR TKI treated patients developed a T790M mutation (p-value 0.02). Progression free survival (PFS) was comparable in patients treated with irreversible EGFR irrespective of the sensitising primary mutation or the acquisition of p.T790M. CONCLUSIONS: The EGFR p.T790M mutation is the most prominent mechanism of resistance to reversible and irreversible EGFR TKI therapy. Nevertheless there is a statistically significant difference of p.T790M acquisition between the two types of TKI, which might be of importance for clinical therapy decision.

Immune profile and immunosurveillance in treatment-naive and neoadjuvantly treated esophageal adenocarcinoma.

The outcome in esophageal adenocarcinoma (EAC) is still poor with only 20% of patients in Western populations surviving for more than 5 years. Almost nothing is known about the precise composition of immune cells and their gene expression profiles in primary resected EACs and also nothing compared to neoadjuvant treated EACs. This study analyzes and compares immune profiles of primary resected and neoadjuvant treated esophageal adenocarcinoma and unravels possible targets for immunotherapy. We analyzed 47 EAC in total considering a set of 30 primary treatment-naive EACs and 17 neoadjuvant pretreated (12 × CROSS, 5 × FLOT) using the Nanostring's panel-based gene expression platform including 770 genes being important in malignant tumors and their immune micromileu. Most of the significantly altered genes are involved in the regulation of immune responses, T-and B cell functions as well as antigen processing. Chemokine-receptor axes like the CXCL9, -10,-11/CXCR3- are prominent in esophageal adenocarcinoma with a fold change of up to 9.5 promoting cancer cell proliferation and metastasis. ARG1, as a regulator of T-cell fate is sixfold down-regulated in untreated primary esophageal tumors. The influence of the currently used neoadjuvant treatment revealed a down-regulation of nearly all important checkpoint markers and inflammatory related genes in the local microenvironment. We found a higher expression of checkpoint markers like LAG3, TIM3, CTLA4 and CD276 in comparison to PD-L1/PD-1 supporting clinical trials analyzing the efficacy of a combination of different checkpoint inhibitors in EACs. We found an up-regulation of CD38 or LILRB1 as examples of additional immune escape mechanism.

Comparison of in situ and extraction-based methods for the detection of MET amplifications in solid tumors.

In EGFR-treatment naive NSCLC patients, high-level MET amplification is detected in approximately 2-3% and is considered as adverse prognostic factor. Currently, clinical trials with two different inhibitors, capmatinib and tepotinib, are under way both defining different inclusion criteria regarding MET amplification from proven amplification only to defining an exact MET copy number. Here, 45 patient samples, including 10 samples without MET amplification, 5 samples showing a low-level MET amplification, 10 samples with an intermediate-level MET amplification, 10 samples having a high-level MET amplification by a MET/CEN7 ratio ≥2.0 and 10 samples showing a high-level MET amplification with GCN ≥6, were evaluated by MET FISH, MET IHC, a ddPCR copy number assay, a NanoString nCounter copy number assay and an amplicon-based parallel sequencing. The MET IHC had the best concordance with MET FISH followed by the NanoString copy number assay, the ddPCR copy number assay and the custom amplicon-based parallel sequencing assays. The concordance was higher in the high-level amplified cohorts than in the low- and intermediate-level amplified cohorts. In summary, currently extraction-based methods cannot replace the MET FISH for the detection of low-level, intermediate-level and high-level MET amplifications, as the number of false negative results is very high. Only for the detection of high-level amplified samples with a gene copy number ≥6 extraction-based methods are a reliable alternative.

First report on two cases of pleomorphic dermal sarcoma successfully treated with immune checkpoint inhibitors.

Pleomorphic dermal sarcoma (PDS) is one of the most common sarcoma of the skin. Currently, limited treatment options exist for advanced stages of the disease. While immune checkpoint inhibitors (CPIs) have revolutionized cancer treatment options-their efficacy in PDS has not been explored yet. Here, we present two advanced PDS cases that showed response to anti-PD-1 therapy. Patient A had a locally metastasized PDS and reached a complete remission of the disease after eight cycles of Pembrolizumab. Patient B developed an inoperable relapse of PDS with a complete remission of the disease 4 months after treatment with Pembrolizumab in combination with radiotherapy. To our knowledge, this is the first report of two individuals with advanced PDS that successfully underwent anti-PD1 treatment. By comparing the immune micromilieu to a previously published cohort, we show that the two cases are representative for PDS tumors - potentially making these results more generalizable.

Immune-phenotyping of pleomorphic dermal sarcomas suggests this entity as a potential candidate for immunotherapy.

BACKGROUND: Pleomorphic dermal sarcomas (PDS) are sarcomas of the skin with local recurrences in up to 28% of cases, and distant metastases in up to 20%. Although recent evidence provides a strong rational to explore immunotherapeutics in solid tumors, nothing is known about the immune environment of PDS. METHODS: In the current study, a comprehensive immune-phenotyping of 14 PDS using RNA and protein expression analyses, as well as quantitative assessment of immune cells using an image-analysis tool was performed. RESULTS: Three out of 14 PDS revealed high levels of CD8-positive tumor-infiltrating T-lymphocytes (TILs), also showing elevated levels of immune-related cytokines such as IL1A, IL2, as well as markers that were very recently linked to enhanced response of immunotherapy in malignant melanoma, including CD27, and CD40L. Using a multivariate analysis, we found a number of differentially expressed genes in the CD8-high group including: CD74, LYZ and HLA-B, while the remaining cases revealed enhanced levels of immune-suppressive cytokines including CXCL14. The "CD8-high" PDS showed strong MHC-I expression and revealed infiltration by PD-L1-, PD-1- and LAG-3-expressing immune cells. Tumor-associated macrophages (TAMs) predominantly consisted of CD68 + , CD163 + , and CD204 + M2 macrophages showing an accentuation at the tumor invasion front. CONCLUSIONS: Together, we provide first explorative evidence about the immune-environment of PDS tumors that may guide future decisions whether individuals presenting with advanced PDS could qualify for immunotherapeutic options.

Advance of theragnosis biomarkers in lung cancer: from clinical to molecular pathology and biology.

One distinct molecular subtype of non-small cell lung cancer (NSCLC) is defined by rearrangement of the anaplastic lymphoma kinase (ALK). The increasing knowledge over the last years has enabled the continuous improvement of ALK inhibitors; however, resistance in these patients remains a major concern. In this review, we summarize recent findings in ALK+-adenocarcinoma of the lung, highlighting the role of TP53 mutations in this specific cancer type and suggest new diagnostic strategies for the future, in order to improve patient's outcome.