Anaplastic Lymphoma Kinase Variants and the Percentage of ALK-Positive Tumor Cells and the Efficacy of Crizotinib in Advanced NSCLC

ALK Amplification and Rearrangements Are Recurrent Targetable Events in Congenital and Adult Glioblastoma

PURPOSE

Anaplastic lymphoma kinase (ALK) aberrations have been identified in pediatric-type infant gliomas, but their occurrence across age groups, functional effects, and treatment response has not been broadly established.

EXPERIMENTAL DESIGN

We performed a comprehensive analysis of ALK expression and genomic aberrations in both newly generated and retrospective data from 371 glioblastomas (156 adult, 205 infant/pediatric, and 10 congenital) with in vitro and in vivo validation of aberrations.

RESULTS

ALK aberrations at the protein or genomic level were detected in 12% of gliomas (45/371) in a wide age range (0-80 years). Recurrent as well as novel ALK fusions (LRRFIP1-ALK, DCTN1-ALK, PRKD3-ALK) were present in 50% (5/10) of congenital/infant, 1.4% (3/205) of pediatric, and 1.9% (3/156) of adult GBMs. ALK fusions were present as the only candidate driver in congenital/infant GBMs and were sometimes focally amplified. In contrast, adult ALK fusions co-occurred with other oncogenic drivers. No activating ALK mutations were identified in any age group. Novel and recurrent ALK rearrangements promoted STAT3 and ERK1/2 pathways and transformation in vitro and in vivo. ALK-fused GBM cellular and mouse models were responsive to ALK inhibitors, including in patient cells derived from a congenital GBM. Relevant to the treatment of infant gliomas, we showed that ALK protein appears minimally expressed in the forebrain at perinatal stages, and no gross effects on perinatal brain development were seen in pregnant mice treated with the ALK inhibitor ceritinib.

CONCLUSIONS

These findings support use of brain-penetrant ALK inhibitors in clinical trials across infant, pediatric, and adult GBMs. See related commentary by Mack and Bertrand, p. 2567.

The percentage of ALK-positive cells and the efficacy of first-line alectinib in advanced non-small cell lung cancer: is it a novel factor for stratification? (Turkish Oncology Group Study)

INTRODUCTION

Alectinib is an effective second-generation ALK tyrosine kinase inhibitor (TKI) used in the first-line treatment of patients with advanced ALK-positive NSCLC. Recent studies demonstrated that the percentage of ALK-positive tumor cells in patient groups receiving crizotinib might affect outcomes. This study aimed to investigate whether the percentage of ALK-positive cells had a predictive effect in patients with advanced NSCLC who received first-line Alectinib as ALK-TKI.

MATERIALS AND METHODS

This retrospective study included patients with advanced-stage NSCLC who received alectinib as a first-line ALK-TKI and whose percentage of ALK-positive cells was determined by FISH at 27 different centers. Patients who received any ALK-TKI before alectinib were not included in the study. Patients were separated into two groups according to the median (40%) value of the percentage of ALK-positive cells (high-positive group ≥ 40% and low-positive group < 40%). The primary endpoint was PFS, and the secondary endpoints were OS, ORR, and PFS of the subgroups based on different threshold values for the percentage of ALK-positive cells.

RESULTS

211 patients were enrolled (48.3% female, 51.7% male) to study. 37% (n = 78) of the patients had received chemotherapy previously. After a median of 19.4 months of follow-up, the median PFS was not reached in the high-positive group (n = 113), but it was 10.8 months in the low-positive group (n = 98) (HR 0.39; 95% CI 0.25-0.60, p < 0.001). The median OS in the high-positive group was not reached, whereas it was 22.8 months in the low-positive group (HR 0.37; 95% CI 0.22-0.63, p < 0.001). ORR was significantly higher in the high-positive group (87.2 vs. 68.5%; p = 0.002). According to the cut-off values of < 20%, 20-39%, 40-59%, and ≥ 60%, the median PFS was 4.5, 17.1, and 26 months, respectively, and could not be reached in the ≥ 60% group.

CONCLUSION

Our study demonstrated that the efficacy of alectinib varies significantly across patient subgroups with different percentages of ALK-positive cells. If these findings are prospectively validated, the percentage of ALK-positive cells may be used as a stratification factor in randomized trials comparing different ALK-TKIs.

Dramatic response to alectinib in a lung adenocarcinoma patient harboring a Novel SSFA2-ALK fusion

ALK (anaplastic lymphoma kinase) gene rearrangements have been reported in 3-5% of NSCLC patients. Different ALK fusion forms can mediate different downstream signaling pathways and may exhibit different sensitivities to ALK tyrosine kinase inhibitors (TKIs). To identify more fusion partners that are sensitive to ALK-TKIs, we present a case of 46-year-old woman with stage IV lung adenocarcinoma. NGS panel analysis suggested that a novel SSFA2-ALK fusion was identified in this patient. Moreover, this fusion was validated through IHC (VENTANA ALK (D5F3) antibody) and FISH (ZytoLight ALK Break Apart FISH Probe). Importantly, to the best of our knowledge, there is no report about SSFA2-ALK fusion in solid cancers. Moreover, the patient achieved an admirable response to alectinib, with a clinical evaluation of complete response (CR). In summary, our findings expand the spectrum of ALK fusion patterns and provide robust evidence for the precise administration of alectinib in the future.

The impact of the ALK fusion variant on clinical outcomes in EML4-ALK patients with NSCLC: a systematic review and meta-analysis

Background: Recent studies showed that ALK-fusion variants are associated with heterogeneous clinical outcomes. However, contradictory conclusions have been drawn in other studies showing no correlation between ALK variants and prognoses. Methods: A systematic review and meta-analysis was performed to evaluate the prognostic value of EML4-ALK fusion variants for patient outcomes. Results: 28 studies were included in the analysis. According to the pooled results, patients harboring variant 1 showed equivalent progression-free survival (PFS) and overall survival (OS) with non-v1 patients (hazard ratio [HR] for PFS: 0.91 [0.68-1.21]; p = 0.499; OS: 1.12 [0.73-1.72]; p = 0.610). Similarly, patients with v3 showed the same disease progress as non-v3 patients (pooled HR for PFS = 1.07 [0.72-1.58]; p = 0.741). However, pooled results for OS suggested that patients with v3 had worse survival than non-v3 patients (HR = 3.44 [1.42-8.35]; p = 0.006). Conclusion: Results suggest that patients with v1 exhibited no significant difference from non-v1 in terms of OS and PFS, while v3 was associated with shorter OS in ALK-positive patients with non-small cell lung cancer.

Clinicopathological features and resistance mechanisms in HIP1-ALK-rearranged lung cancer: A multicenter study

Anaplastic lymphoma kinase (ALK)-rearranged non-small cell lung cancer (NSCLC) respond well to ALK tyrosine kinase inhibitors (TKIs), and echinoderm microtubule-associated protein-like 4 (EML4)-ALK-rearranged NSCLC accounts for the majority of those patients. However, few studies have evaluated ALK-TKIs treatment for patients with huntingtin-interacting protein 1 (HIP1)-ALK fusions. This retrospective study evaluated the clinicopathological characteristics, genomic features, response to ALK-TKIs, and resistance mechanisms in 11 cases with HIP1-ALK fusions from five Chinese centers. Patients who received crizotinib at the Chinese centers had an objective response rate of 90% [9/10 cases, 95% confident index (CI): 54.1%-99.5%], median progression-free survival of 17.9 months (95% CI: 5.8-NA months), and median overall survival of 58.8 months (95% CI: 24.7-NA months). One patient who received first-line lorlatinib treatment achieved partial response for > 26.5 months. Despite the small sample size, HIP1-ALK (H21:A20) variant was the most common variant (four of 11 cases, 36.4%) and associated with better outcomes. Among the 11 cases, there were eight patients having available specimens for genetic testing before ALK-TKIs treatment and four patients undergoing biopsy after ALK-TKIs failure. The most common coexisting gene was TP53 among 11 patients and two of four patients after crizotinib failure harbored acquired ALK mutations (e.g., L1152V/Q1146K and L1196M). Brigatinib treatment appeared to be effective for a patient who failed crizotinib treatment because of the L1152V/Q1146K mutations, which might be related to increased binding affinity to these mutants. Although HIP1-ALK-rearranged NSCLC appears to initially respond well to ALK-TKIs, crizotinib resistance may be correlated with the AKAP9-BRAF fusion, ALK compound mutations (L1152V/Q1146K), and the ALK L1196M mutation. Larger studies are needed to evaluate the significance of HIP1-ALK-rearranged NSCLC.

The Resistance Mechanisms and Treatment Strategies for ALK-Rearranged Non-Small Cell Lung Cancer

Anaplastic lymphoma kinase (ALK) is a validated molecular target for non-small-cell lung cancer (NSCLC). The use of tyrosine kinase inhibitors (TKIs) has led to significantly improved survival benefits. However, the clinical benefits of targeting ALK using TKIs are limited due to the emergence of drug resistance. The landscape of resistance mechanisms and treatment decisions has become increasingly complex. Therefore, continued research into new drugs and combinatorial therapies is required to improve outcomes in NSCLC. In this review, we explore the resistance mechanisms of ALK TKIs in advanced NSCLC in order to provide a theoretical basis and research ideas for solving the problem of ALK drug resistance.

Sensitivity of eight types of ALK fusion variant to alectinib in ALK-transformed cells

Tyrosine kinase inhibitors of anaplastic lymphoma kinase (ALK-TKIs) including alectinib have been the standard therapy against ALK fusion gene-positive non–small cell lung cancers (NSCLCs). Many ALK fusion variants have been identified in NSCLCs, and the predominant variants are echinoderm microtubule-associated protein-like 4-ALK (EML4-ALK) variant 1 (V1), V2 and V3a/b. However, there have been conflicting reports on the clinical responses of these variants to ALK-TKIs, and there are few reports on other less common ALK variants. To examine the influence of ALK variants on the efficacy of ALK-TKIs, we analyzed the sensitivity to alectinib of eight types of ALK variant: three major variants (V1, V2 and V3a) and five less common variants (V4; kinesin family member 5-ALK; kinesin light chain 1-ALK; striatin, calmodulin-binding protein-ALK; and tropomyosin-receptor kinase fused gene-ALK). Analysis was done by cell-free kinase assays using the recombinant proteins and by cell, growth assays using murine Ba/F3 cells expressing ALK variants. The kinase activity of each recombinant protein was significantly inhibited by alectinib. Intracellular ALK phosphorylation levels and its downstream signaling mediators, STAT3 and ERK, were suppressed by alectinib in each ALK variant-expressing Ba/F3 cell. Each cellular proliferation was markedly inhibited by alectinib treatment. There was no significant difference in the IC₅₀ values between cells, with a <3.6-fold difference in responsiveness. In conclusion, these eight ALK variants had similar sensitivity to alectinib in vitro, indicating that it may not be possible to predict the response to alectinib just by determination of the ALK variant type in ALK fusion-positive NSCLCs.

Association of anaplastic lymphoma kinase variants and alterations with ensartinib response duration in non-small cell lung cancer

Background

Here, we aimed to assess the association of ALK variants and alterations with ensartinib response duration in NSCLC, and explore the potential value of computed tomography (CT) radiomic features in predicting progression‐free survival (PFS).

Methods

We enrolled 88 patients with identified ALK variant NSCLC in a multicenter phase 2 trial, and assessed the impact of ALK variants and secondary ALK alterations on the clinical outcome (response duration) of patients receiving ensartinib. We also established a multifactorial model of clinicopathological and quantitative CT radiomic features to predict PFS and risk stratification. Kaplan–Meier analysis was conducted to identify risk factors for tumor progression.

Results

Univariate analysis indicated a statistical difference (p = 0.035) in PFS among ALK variants in three classifications (V1, V3, and other variants). Secondary ALK alterations were adversely associated with PFS both in univariate (p = 0.008) and multivariate (p = 0.04) analyses and could identify patients at high risk for early progression in the Kaplan–Meier analysis (p = 0.002). Additionally, response duration to crizotinib <1 year and liver metastasis were adversely associated with PFS. The combined model, composed of clinicopathological signature and CT radiomic signature, showed good prediction ability with the area under the receiver operating characteristic curve being 0.85, and 0.89 in the training and validation dataset respectively.

Conclusions

Our study showed that secondary ALK alterations were adversely associated with ensartinib efficacy, and that ALK variants might not correlate with PFS. The quantitative radiomic signature provided added prognostic prediction value to the clinicopathological features.

Going beneath the tip of the iceberg. Identifying and understanding EML4-ALK variants and TP53 mutations to optimize treatment of ALK fusion positive (ALK+) NSCLC

Since the discovery of echinoderm microtubule-associated protein-like 4 (EML4) and anaplastic lymphoma kinase (ALK) gene fusion in non-small cell lung carcinoma (NSCLC) in 2007, more than 10 EML4-ALK variants based on the exon breakpoints in EML4 have been identified. Unlike other receptor tyrosine kinase fusion positive NSCLC such as ROS1 or RET fusion, EML4-ALK is the dominant fusion variant in ALK+ NSCLC accounting for approximately 85 % of all fusion variants in ALK+ NSCLC. Currently, eight EML4-ALK variants are generally recognized with a number (1, 2, 3a/b, 4', 5a/b, 5', 7, 8) with EML4-ALK variants 1 and 3 being the two most common variants accounting for 75-80 % of the total EML4-ALK variants. Preclinical, retrospective analyses of institutional databases, and global randomized phase 3 trials have demonstrated differential clinical response (overall response rate, progression-free survival) to ALK tyrosine kinase inhibitors (TKIs) between the "short" (v3 and v5) and "long" (v1, v2, v5', v7, and v8) EML4-ALK variants. We discuss in more details how EML4-ALK variant structure influences protein stability and response to ALK TKIs. Additionally, the most recalcitrant single solvent-front mutation ALK G1202R is more prone to develop among EML4-ALK v3 following sequential use of next-generation ALK TKIs. Furthermore, TP53 mutations being the most common genomic co-alterations in ALK+ NSCLC also contribute to the heterogeneous response to ALK TKIs. Recognizing ALK+ NSCLC is not one homogeneous disease entity but comprised of different ALK fusion variants with different underlying genomic alterations in particular TP53 mutations that modulate treatment response will provide insight into the further optimization of treatment of ALK+ NSCLC patients potentially leading to improvement in survival.

Targeting EML4-ALK gene fusion variant 3 in thyroid cancer

Finding targetable gene fusions can expand the limited treatment options in radioactive iodine-refractory (RAI-r) thyroid cancer. To that end, we established a novel cell line 'JVE404' derived from an advanced RAI-r papillary thyroid cancer (PTC) patient, harboring an EML4-ALK gene fusion variant 3 (v3). Different EML4-ALK gene fusions can have different clinical repercussions. JVE404 cells were evaluated for cell viability and cell signaling in response to ALK inhibitors crizotinib, ceritinib and lorlatinib, in parallel to the patient's treatment. He received, after first-line lenvatinib, crizotinib (Drug Rediscovery Protocol (DRUP) trial), and lorlatinib (compassionate use). In vitro treatment with crizotinib or ceritinib decreased viability in JVE404, but most potently and significantly only with lorlatinib. Western blot analysis showed a near total decrease of 99% and 89%, respectively, in pALK and pERK expression levels in JVE404 cells with lorlatinib, in contrast to remaining signal intensities of a half and a third of control, respectively, with crizotinib. The patient had a 6-month lasting stable disease on crizotinib, but progressive disease occurred, including the finding of cerebral metastases, at 8 months. With lorlatinib, partial response, including clinical cerebral activity, was already achieved at 11 weeks' use and ongoing partial response at 7 months. To our best knowledge, this is the first reported case describing a patient-specific targeted treatment with lorlatinib based on an EML4-ALK gene fusion v3 in a thyroid cancer patient, and own cancer cell line. Tumor-agnostic targeted therapy may provide valuable treatment options in personalized medicine.

Concomitant mutation status of ALK-rearranged non-small cell lung cancers and its prognostic impact on patients treated with crizotinib

Background

In non-small cell lung cancer (NSCLC), anaplastic lymphoma kinase (ALK) rearrangement characterizes a subgroup of patients who show sensitivity to ALK tyrosine kinase inhibitors (TKIs). However, the prognoses of these patients are heterogeneous. A better understanding of the genomic alterations occurring in these tumors could explain the prognostic heterogeneity observed in these patients.

Methods

We retrospectively analyzed 96 patients with NSCLC with ALK detected by immunohistochemical staining (VENTANA anti-ALK(D5F3) Rabbit Monoclonal Primary Antibody). Cancer tissues were subjected to next-generation sequencing using a panel of 520 cancer-related genes. The genomic landscape, distribution of ALK fusion variants, and clinicopathological characteristics of the patients were evaluated. The correlations of genomic alterations with clinical outcomes were also assessed.

Results

Among the 96 patients with immunohistochemically identified ALK fusions, 80 (83%) were confirmed by next-generation sequencing. TP53 mutation was the most commonly co-occurring mutation with ALK rearrangement. Concomitant driver mutations [2 Kirsten rat sarcoma viral oncogene homolog (KRAS) G12, 1 epidermal growth factor receptor (EGFR) 19del, and 1 MET exon 14 skipping] were also observed in 4 adenocarcinomas. Echinoderm microtubule associated protein-like 4 (EML4)-ALK fusions were identified in 95% of ALK-rearranged patients, with 16.2% of them also harboring additional non-EML4-ALK fusions. Nineteen non-EML4 translocation partners were also discovered, including 10 novel ones. Survival analyses revealed that patients concurrently harboring PIK3R2 alterations showed a trend toward shorter progression-free survival (6 vs. 13 months, P=0.064) and significantly shorter overall survival (11 vs. 32 months, P=0.004) than did PIK3R2-wild-type patients. Patients with concomitant alterations in PI3K the signaling pathway also had a shorter median overall survival than those without such alterations (23 vs. 32 months, P=0.014), whereas progression-free survival did not differ significantly.

Conclusions

The spectrum of ALK-fusion variants and the landscape of concomitant genomic alterations were delineated in 96 NSCLC patients. Our study also demonstrated the prognostic value of concomitant alterations in crizotinib-treated patients, which could facilitate improved stratification of ALK-rearranged NSCLC patients in the selection of candidates who could optimally benefit from therapy.

The effect of EML4-ALK break-apart ratio on crizotinib outcomes in non-small cell lung cancer harboring EML4-ALK rearrangement

PURPOSE

Anaplastic lymphoma kinase (ALK) gene rearrangement exists in approximately 3-7% of non-small cell lung cancer (NSCLC) and more than 15% split or isolated red signals among 50 tumor nuclei scored in the FISH analysis defines as ALK-positive. The previous studies showed that the high EGFR mutational load related to better outcomes in EGFR mutant NSCLC. Therefore, we aimed to investigate the effect of the ALK break-apart ratio on treatment outcome in metastatic ALK-positive NSCLC.

METHODS

The patients (pts) who ALK-positive and treated with crizotinib were retrospectively enrolled. The 30%, 40%, 50%, 60%, and 70% break-apart ratios were determined as a threshold value, and each of these was evaluated separately. Based on the results of these analyses, we detected the optimal threshold value and also performed further investigations.

RESULTS

A total of 70 patients were enrolled in the study. The most significant decrease in the risk of the progression or death was detected at the 50% threshold value and it was accepted as the optimal threshold. The median PFS was 17.9 vs. 7.06 months (mo) in the pts with high ALK rearrangement than low (HR: 0.43, 95% CI 0.24-0.76, p 0.004). The median OS was also significant longer in high ALK rearrange group (44.6 mo vs. 16.8 mo; HR: 0.37, 95% Cl 0.1883-0.7315; p 0.004). The intracranial progression during crizotinib treatment was significantly frequent in the pts with high ALK rearrangement (62.5-32.5%, P 0.039) DISCUSSION: In this study, we found that the high break-apart ratio can predict the extent of benefit from targeted therapy in ALK-positive NSCLC patients. Based on the results of this study, the percentage of the ALK rearrangement can be used to predict treatment outcome and to choose the optimal targeted agent in the treatment of metastatic ALK-positive NSCLC.

Complex ALK Fusions Are Associated With Better Prognosis in Advanced Non-Small Cell Lung Cancer

Background

Echinoderm microtubule-associated protein-like 4 (EML4) is the canonical anaplastic lymphoma kinase (ALK) fusion partner in non-small cell lung cancer (NSCLC), and ALK-positive patients showed promising responses to ALK tyrosine kinase inhibitors (TKIs). However, studies that comprehensively investigate ALK TKI treatment in patients with different ALK fusion patterns are still lacking.

Methods

Ninety-eight ALK-positive patients with advanced NSCLC were retrospectively studied for their response to crizotinib and subsequent treatments. Comprehensive genomic profiling (CGP) was conducted to divide patients into different groups based on their ALK fusion patterns. Non-canonical ALK fusions were validated using RNA-sequencing.

Results

54.1% of patients had pure canonical EML4-ALK fusions, 19.4% carried only non-canonical ALK fusions, and 26.5% harbored complex ALK fusions with coexisting canonical and non-canonical ALK fusions. The objective response rate and median progression-free survival to crizotinib treatment tended to be better in the complex ALK fusion group. Notably, patients with complex ALK fusions had significantly improved overall survival after crizotinib treatment (p = 0.012), especially when compared with the pure canonical EML4-ALK fusion group (p = 0.010). The complex ALK fusion group also tended to respond better to next-generation ALK TKIs, which were used as later-line therapies. Most identified non-canonical ALK fusions were likely to be expressed in tumors, and some of them formed canonical EML4-ALK transcripts during mRNA maturation.

Conclusion

Our results suggest NSCLC patients with complex ALK fusions could potentially have better treatment outcomes to ALK TKIs therapy. Also, diagnosis using CGP is of great value to identify novel ALK fusions and predict prognosis.

ALK variants, PD-L1 expression, and their association with outcomes in ALK-positive NSCLC patients

It remains unclear how programmed death-ligand 1 (PD-L1) expression interacts with anaplastic lymphoma kinase (ALK) mutation, its variants, and the outcome of treatment. One hundred and twenty four out of 1255 patients (9.9%) were deemed ALK-positive by the Ventana IHC assay. PD-L1 status and ALK variants were available in 100 and 59 patients, respectively. PD-L1 positive (TPS ≥ 1%) and strong positive (TPS ≥ 50%) rate was 50% and 16%, respectively. A total of 64 variant types were detected in 59 patients. V1 (32.8%) and V3a/b (28.1%) were the most common variants. There was no significant association between ALK variants and the PD-L1 expression. The presence of V3a/b subtype independently predicted a worse overall survival in patients receiving ALK inhibitor(s) (aHR 5.10 [95% CI 1.22–21.25], P = 0.025) and platinum plus pemetrexed (aHR 9.62 [95% CI 1.90–48.80], P = 0.006). While incorporating ALK variants and PD-L1 expression together, patients with non-V3a/b/positive PD-L1 showed a trend towards longer OS. In conclusion, ALK-positive NSCLC patients possess a high PD-L1 expression rate. Although there was no significant association between PD-L1 expression and ALK variants, the outcome of ALK-positive patients could be sorted by these two biomarkers.

A rare double ALK fusion variant EML4-ALK and CDK15-ALK in lung adenocarcinoma and response to crizotinib: A case report

RATIONALE

The anaplastic lymphoma kinase (ALK) fusion has been identified to be a driver gene in lung cancer, and serves as important diagnostic and therapeutic targets. Owing to the advanced sequencing technologies, new partner genes of ALK have been constantly detected.

PATIENT CONCERNS

A 55-year-old Chinese woman went to our hospital because of cough and expectoration for 1 year. The patient had no fever, chest pain and hemoptysis.

DIAGNOSES

She was diagnosed with lung adenocarcinoma. Because she had no operational condition, combination chemotherapy with docetaxel and cisplatin (CP) for 4 cycles was adopted. However, computed tomography (CT) scan indicated progression disease (PD). To explore possibility of targeted therapy, the tumor samples were subjected to next-generation sequencing (NGS), and a rare double ALK fusion variant EML4-ALK and CDK15-ALK was identified.

INTERVENTIONS AND OUTCOMES

The patient subsequently received crizotinib treatment, and achieved partial response (PR). No significant drug related adverse reactions were found during crizotinib treatment. The progression-free survival achieved 23 months.

LESSONS

Together, we identified a rare double ALK fusion variant, EML4-ALK and CDK15-ALK, in a patient with lung adenocarcinoma. The patient benefited from crizotinib treatment, which could provide a certain reference for the patients with such gene alteration.

Impact of ALK variants on brain metastasis and treatment response in advanced NSCLC patients with oncogenic ALK fusion

Background

To investigate the impact of ALK variants on the features of brain metastases (BM), the outcome of chemotherapy and targeted therapy using crizotinib, as well as the progression pattern in patients with ALK fusion.

Methods

Patients with ALK fusion were retrospectively collected from January 2013 to July 2017 in Shanghai Pulmonary Hospital. ALK rearrangements were identified via ARMS-PCR. ALK variants were identified via Sanger Sequencing.

Results

A total of 135 patients and 41 with brain metastasis were identified. Radiological features showed that the patients with ALK variant 1 had a larger BM size compared with patients with ALK non-variant 1 (median tumor size: 16.89 vs. 11.01 mm, P=0.031). Similar time to treatment failure (TTF) was observed in patients with ALK variant 1 and non-variant 1 who received first-line crizotinib (median TTF: 15.7 vs. 13.8 months, HR =0.75, P=0.34). Patients with ALK variant 1 who had baseline BM had significantly shorter TTF than non-variant 1 with baseline BM when treated with first-line crizotinib (median TTF: 9.1 vs. 14.9 months, HR =2.68, P=0.037). In patients treated with chemotherapy, ALK variant 1 was associated with inferior TTF (median TTF: 5.6 vs. 8.1 months, HR =1.66, P=0.039). Progression pattern was similar between ALK variant 1 and non-variant 1.

Conclusions

Patients with ALK variant 1 and baseline BM had inferior TTF on first-line crizotinib treatment and presented with more aggressive radiological features. Patients with ALK non-variant 1 had better clinical outcome on first-line chemotherapy.

Distribution of ALK Fusion Variants and Correlation with Clinical Outcomes in Chinese Patients with Non-Small Cell Lung Cancer Treated with Crizotinib

BACKGROUND

ALK-rearranged non-small cell lung cancer (NSCLC) represents a molecular subgroup with high sensitivity to ALK inhibitors. Crizotinib, a US Food and Drug Administration (FDA)-approved tyrosine kinase inhibitor for treating ALK-rearranged NSCLC, has shown remarkable response in ALK-positive NSCLC. However, heterogeneity of clinical responses exists among different ALK fusion partners. Several small studies have investigated the correlation between fusion partners and efficacy, but not yielded consistent results.

OBJECTIVE

We investigated the prevalence of ALK rearrangements in a Chinese NSCLC population, and correlated clinical outcomes of crizotinib with different ALK partners/variants.

PATIENTS AND METHODS

We retrospectively reviewed genomic profiling and clinical data of 110 ALK-rearranged NSCLC patients from five centers. The clinical response to crizotinib and survival data in ALK-positive patients was retrospectively analyzed.

RESULTS

A total of 134 ALK rearrangements with 39 partners were identified in 110 patients (5.6%) among a cohort of 1971 NSCLC patients. The most frequently occurring ALK fusion partner was EML4, which was identified in 71.6% (96/134) of all of the rearrangements in 87.3% (96/110) patients, and with variant 3 (41/96, 42.7%) as the main variant type. No statistically significant differences in terms of progression-free survival (PFS) and overall survival (OS) were found between EML4-ALK and non-EML4-ALK NSCLC patients in our cohort (PFS, p = 0.207; OS, p = 0.678). Outcomes did not differ significantly between patients above and below 40 years of age (PFS, p = 0.427; OS, p = 0.686), nor between patients treated with crizotinib in different lines of therapy (PFS, p = 0.171; OS, p = 0.922). For EML4-ALK-positive NSCLC (n = 96), patients harboring variant 3 or variant 5 displayed significantly lower PFS and OS than those with other variants (PFS, 8.6 vs. 11.3 months, p = 0.046; OS, 31.0 vs. 37.6 months, p = 0.026). In addition, patients with a single EML4-ALK rearrangement event displayed favorable PFS (10.0 vs. 7.2 months, p = 0.040) and OS (36.0 vs. 20.0 months, p = 0.029) compared to those harboring multiple ALK rearrangements.

CONCLUSIONS

This study illustrates the patterns of ALK fusion variants present in Chinese NSCLC patients and might help explain heterogeneous clinical outcomes to crizotinib treatment according to different ALK fusion variants.

Unique molecular features and clinical outcomes in young patients with non-small cell lung cancer harboring ALK fusion genes

PURPOSE

This study aimed to determine the molecular features and clinical outcomes of young patients with non-small cell lung cancer (NSCLC) harboring ALK fusion genes.

METHODS

We interrogated the genomic profile of 1652 patients with lung cancer who underwent targeted next-generation sequencing to screen for candidate oncogenic drivers using histological specimens acquired from January 2016 to December 2018.

RESULTS

ALK fusions were identified in 101 NSCLC patients, and 52 of them were diagnosed before the age of 50 years (52/367, 14.2%). Of the 52 patients with early-onset disease, 22 (42.3%) were male and 43 (82.7%) never smoked; the median patient age was 44 years (range 28-50 years). The most frequently occurring ALK fusion partner was EML4, which was identified in 80.8% (42/52) of young patients. Compared to the older patients, patients with early-onset disease were more likely to harbor EML4-ALK variant 1 (38.5% vs. 14.3%; P = 0.007). We also identified rare ALK fusions, including CHRNA7-ALK, TACR1-ALK, HIP1-ALK, DYSF-ALK and ITGAV-ALK, in patients with early-onset disease, and patients with these fusions responded well to crizotinib treatment. A statistically significant difference was observed in progression-free survival (PFS) between the young patients and older patients who received crizotinib as the first-line therapy (17.5 months vs 9.0 months, P = 0.048). However, the median PFS of young patients harboring concurrent TP53 mutations was only 6.2 months.

CONCLUSION

Unique genetic characteristics were found in ALK-rearranged NSCLC patients with early disease onset, and these patients responded better to crizotinib and had longer PFS compared to patients with later disease onset. However, patients with concomitant TP53 mutations may not have a significant response to treatment.

The Impact of Clinical Factors, ALK Fusion Variants, and BIM Polymorphism on Crizotinib-Treated Advanced EML4-ALK Rearranged Non-small Cell Lung Cancer

Patients' clinical factors and genetics factors such as anaplastic lymphoma kinase (ALK) fusion variants and BIM (Bcl-2-like 11) polymorphism were reported to be associated with clinical outcome in crizotinib-treated advanced non-small cell lung cancer (NSCLC). However, the results were still controversial. We analyzed outcome of 54 patients with known ALK fusion variants who received crizotinib for advanced NSCLC. Thirty of them had successful BIM polymorphism analysis and 6 (20%) had a BIM deletion. Multivariate Cox regression analysis found that previous anticancer therapy [adjusted hazard ratio (aHR) 1.35, 95% confidence interval (CI), 1.04–1.76 for each additional line of therapy, p = 0.025] and Eastern Cooperative Oncology Group (ECOG) performance status ≥2 (aHR 8.35, 95% CI, 1.52–45.94, p = 0.015) were independent factors for progression-free survival (PFS). Only ECOG performance status ≥2 (aHR 7.20, 95% CI, 1.27–40.79, p = 0.026) was an independent factor for overall survival (OS). Neither ALK fusion variants nor the presence of a BIM deletion was associated with crizotinib PFS or OS. After adjusting with clinical factors, different ALK variants and BIM polymorphism might not be independent factors for crizotinib PFS or OS in advanced NSCLC with ALK rearrangement.

The prevalence of EML4-ALK variants in patients with non-small-cell lung cancer: a systematic review and meta-analysis

To investigate the prevalence of EML4-ALK variants in non-small-cell lung cancer (NSCLC) patients. Materials & methods: Database of Pubmed, Embase, Medline and Cochrane Library were searched systematically to April 2018. Results: A total of 39 articles including 1903 NSCLC patients with ALK positive were recruited. The overall pooled prevalence for EML4-ALK variant 1 to 3 was 81.84% (95% CI: 76.68-86.99%), ranging from 86.64% tested by RT-PCR to 70.85% tested by other methods (p = 0.00). Subgroup analysis showed that the pooled prevalences of variant 1, 2 and 3 were 40.38% (95% CI: 34.83-45.93%), 6.59% (95% CI: 4.27-8.91%) and 26.54% (95% CI: 20.89-32.2%), respectively. Conclusion: This present study provides the exact prevalence of EML4-ALK rearrangement in different variants for NSCLC patients with ALK positive.

Long-term complete response in a patient with postoperative recurrent ALK-rearranged lung adenocarcinoma treated with crizotinib: A case report

Anaplastic lymphoma kinase (ALK) gene rearrangements are identified in approximately 5% of patients with non-small cell lung cancer (NSCLC). Despite initial dramatic responses to ALK inhibitors, the majority of patients relapse within 1 year, owing to the development of resistance. Herein we present a case of variant type 2 ALK-rearranged lung adenocarcinoma recurrence with multiple lung metastasis that maintained complete response over 5 years with crizotinib, which is the first approved ALK inhibitor. The efficacy of crizotinib may vary among ALK fusion variants and thus, variant type may represent an important factor in guiding the treatment strategy for ALK-rearranged lung adenocarcinoma.

The Percentage of Anaplastic Lymphoma Kinase-Positive Tumor Cells Has Clinical Implications for Patients with Non-Small Cell Lung Cancer

Objectives: Anaplastic lymphoma kinase (ALK) is one of the leading therapeutic targets in patients with non-small cell lung cancer (NSCLC). However, the clinical importance that the percentage of ALK-positive tumor cells has on NSCLC remains unclear. Methods: A total of 344 ALK-positive patients were enrolled in this study. The percentage of ALK-positive tumor cells was identified by fluorescence in situ hybridization. The discrimination and calibration analyses of the nomogram were estimated with Harrell's C-index. Results: Higher percentages (≥50%) of ALK-positive tumor cells were significantly correlated with male gender, poor differentiation, and normal levels of carbohydrate antigen 153 (CA153) and blood platelets (p < 0.05). A shorter first-line progression-free survival (PFS) was correlated with a lower percentage (15-49%) of ALK-positive tumor cells, chemotherapy, a poor performance state, non-adenocarcinoma, as well as abnormal CA153 and Cyfra21-1 levels; and an abnormal thrombin time (p < 0.05). A low percentage of ALK-positive tumor cells, crizotinib treatment, CA153 levels, and neutrophil count were independent risk factors for poor PFS in the multivariate analysis (p < 0.05). The nomogram showed a C-index of 0.76 for first-line PFS. Conclusion: A nomogram including the percentage of ALK-positive tumor cells may act as a crucial indicator for first-line PFS in ALK-positive NSCLC patients.

ALK testing methods: is there a winner or loser?

INTRODUCTION

Anaplastic lymphoma kinase (ALK) is one of the most attractive molecular targets for the treatment of patients with non-small-cell lung cancer. Treatment with ALK inhibitors is recognized as the standard-of-care for patients with ALK gene rearrangements, but it is important to appropriately select patients who will benefit from such treatment. Areas covered: In this article, we review the evidence regarding ALK testing. Immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), and reverse transcription polymerase chain reaction (RT-PCR) are the representative methods for detecting ALK gene fusions. Among these diagnostic modalities, IHC in particular exhibits high sensitivity and specificity for the detection of ALK fusions when appropriately applied and interpreted. Expert commentary: Discrepancies have been reported between the results of IHC and FISH. However, it was revealed that patients with IHC-positivity and FISH-negativity may respond to alectinib, indicating that IHC can be used as a stand-alone method from a clinical standpoint for the identification of patients eligible for treatment with ALK inhibitors. In addition, differences between ALK variants have been reported to affect the prognosis and efficacy of ALK inhibitor-based treatments, and RT-PCR will likely increase in importance as a complementary tool.

Variability in lung cancer response to ALK inhibitors cannot be explained by the diversity of ALK fusion variants

Multiple laboratory evidences indicate that distinct variants of ALK translocations differ in their biochemical properties and responsiveness to ALK tyrosine kinase inhibitors (TKIs). These data are supported by some clinical studies, which showed improved responses to crizotinib in non-small cell lung cancer (NSCLC) patients carrying particular variants of ALK translocation. We retrospectively considered 64 Russian patients with ALK-rearranged NSCLC, who were treated by crizotinib (n = 23), ceritinib (n = 39) or alectinib (n = 2). ALK fusion variants were genotyped by PCR. Median progression-free survival (PFS) approached to 18 and 21 months in subjects with "short" (v.3a/b, v.5a/b) vs. "long" (TAPE-domain containing) fusion variants (p = 0.783), respectively; similar data were obtained while comparing EML4/ALK variant 1 vs. other ALK translocations (19 and 21 months, respectively; p = 0.604). Objective response rates were also strikingly similar in the above groups ("short": 88%, "long": 77%, p = 0.479; variant 1: 76%, other translocations: 81%, p = 0.753). Furthermore, ALK variants did not influence the disease outcomes when patients treated by crizotinib and ceritinib were analyzed separately. Overall, PFS on ALK TKI did not depend on whether the drug was administered upfront or after chemotherapy. Ceritinib produced significantly longer PFS than crizotinib (p = 0.022). In conclusion, this study revealed that distinct ALK translocation variants render similar clinical responsiveness to ALK inhibitors.

Challenges in ALK inhibition of ALK-positive non-small-cell lung cancer: from ALK positivity detection to treatment strategies after relapse

ALK positivity, despite representing only in a small proportion of patients with non-small-cell lung cancer, is worth researching at diagnosis given the possibility to treat these patients with some targeted ALK inhibitors, which are more potent than chemotherapy. Thanks to understanding the resistance mechanisms, newer and more selective inhibitors are now available in clinical practice. Hence, this disease represents, after EGFR inhibition, a largely effective precision medicine approach. However, there are still some clinical situations in which the targeted drug seems to be ineffective. This review discusses some uncertainty about such a 'precision medicine application', focusing on some weaknesses and giving perspectives and suggestions to improve the management of this specific population.

The correlation between crizotinib efficacy and molecular heterogeneity by next-generation sequencing in non-small cell lung cancer

Background

Non-small cell lung cancer (NSCLC) patients with EML4-ALK fusion exhibited various durations of response to crizotinib. Molecular heterogeneity is also one of the factors associated with resistance to crizotinib. This study investigated the relevance of molecular heterogeneity to the clinical efficacy of crizotinib using next-generation sequencing (NGS).

Methods

A total of 52 ALK-positive advanced NSCLC patients were enrolled. The genetic variation was revealed by NGS. We identified different ALK fusion types, allelic fraction (AF) and additional coexisting mutations (ACMs) and evaluated the correlation between the above three factors and clinical response to crizotinib.

Results

Among the group that was detected with ALK+ fusion by immunohistochemistry (IHC), patients detected as ALK- fusion by the NGS method were associated with a shorter progression-free survival (PFS) compared with ALK+ patients by NGS. Moreover, for different ALK fusion types, the median PFS of variant 1/2/3 and other uncommon variants were 305, 557, 242 and 370 days, respectively. Although there was no statistically significant difference (P=0.201), patients with ALK variant 2 appeared to display a longer PFS than other types of variants in this study. There was no significant difference in the relationship between ALK fusion AF and PFS (P=0.639). Additionally, there was no correlation between ACMs and PFS in the three groups (IHC+, IHC+/NGS-, and IHC+/NGS+, P=0.738, 0.801 and 0.550). We analysed the relationship between TP53/FAT3 and PFS in the IHC+/NGS+ group, and there was no statistically significant difference (P=0.712/0.631).

Conclusions

It is necessary to use multiple methods together to detect ALK fusion, and we can continue to carry out the study of the correlation between the different contents of heterogeneity of gene mutations and TKI effects using the NGS method.

Impact of EML4-ALK Variant on Resistance Mechanisms and Clinical Outcomes in ALK-Positive Lung Cancer

Purpose Advanced anaplastic lymphoma kinase ( ALK) fusion-positive non-small-cell lung cancers (NSCLCs) are effectively treated with ALK tyrosine kinase inhibitors (TKIs). However, clinical outcomes in these patients vary, and the benefit of TKIs is limited as a result of acquired resistance. Emerging data suggest that the ALK fusion variant may affect clinical outcome, but the molecular basis for this association is unknown. Patients and Methods We identified 129 patients with ALK-positive NSCLC with known ALK variants. ALK resistance mutations and clinical outcomes on ALK TKIs were retrospectively evaluated according to ALK variant. A Foundation Medicine data set of 577 patients with ALK-positive NSCLC was also examined. Results The most frequent ALK variants were EML4-ALK variant 1 in 55 patients (43%) and variant 3 in 51 patients (40%). We analyzed 77 tumor biopsy specimens from patients with variants 1 and 3 who had progressed on an ALK TKI. ALK resistance mutations were significantly more common in variant 3 than in variant 1 (57% v 30%; P = .023). In particular, ALK G1202R was more common in variant 3 than in variant 1 (32% v 0%; P < .001). Analysis of the Foundation Medicine database revealed similar associations of variant 3 with ALK resistance mutation and with G1202R ( P = .010 and .015, respectively). Among patients treated with the third-generation ALK TKI lorlatinib, variant 3 was associated with a significantly longer progression-free survival than variant 1 (hazard ratio, 0.31; 95% CI, 0.12 to 0.79; P = .011). Conclusion Specific ALK variants may be associated with the development of ALK resistance mutations, particularly G1202R, and provide a molecular link between variant and clinical outcome. ALK variant thus represents a potentially important factor in the selection of next-generation ALK inhibitors.

Efficacy of Pemetrexed-based Chemotherapy in Comparison to Non-Pemetrexed-based Chemotherapy in Advanced, ALK+ Non-Small Cell Lung Cancer

PURPOSE

Previous retrospective studies suggest that anaplastic lymphoma kinase (ALK) mutation-positive (ALK+) non-small cell lung cancer (NSCLC) patients are sensitive to pemetrexed. To determine its efficacy, we retrospectively evaluated clinical outcomes of pemetrexed-based chemotherapy in patients with ALK+ NSCLC.

MATERIALS AND METHODS

We identified 126 patients with advanced, ALK+ NSCLC who received first-line cytotoxic chemotherapy. We compared response, progression-free survival (PFS), and overall survival (OS) rates according to chemotherapy regimens. Furthermore, we evaluated intracranial time to tumor progression (TTP) and proportion of ALK+ cells as prognostic factors.

RESULTS

Forty-eight patients received pemetrexed-based chemotherapy, while 78 received other regimens as first-line treatment. The pemetrexed-based chemotherapy group showed superior overall response (44.7% vs. 14.3%, p<0.001) and disease control (85.1% vs. 62.3%, p=0.008) rates. The pemetrexed-based chemotherapy group also exhibited longer PFS (6.6 months vs. 3.8 months, p<0.001); OS rates were not significantly different. The lack of exposure to second-generation ALK inhibitors and intracranial metastasis on initial diagnosis were independent negative prognostic factors of OS. Intracranial TTP was similar between the treatment groups (32.7 months vs. 35.7 months, p=0.733). Patients who harbored a greater number of ALK+ tumor cells (≥70%) showed prolonged OS on univariate analysis (not reached vs. 44.8 months, p=0.041), but not on multivariate analysis (hazard ratio: 0.19, 95% confidence interval: 0.03-1.42; p=0.106).

CONCLUSION

Pemetrexed-based regimens may prolong PFS in patients with ALK+ NSCLC as a first-line treatment, but are not associated with prolonged OS. Exposure to second-generation ALK inhibitors may improve OS rates in patients with ALK+ NSCLC.

Outcomes of ALK positive lung cancer patients treated with crizotinib or second-generation ALK inhibitor: a monoinstitutional experience

Rearrangement in the anaplastic lymphoma kinase (ALK) gene is one of the oncogenic drivers in non-small cell lung cancer (NSCLC) patients.

Several ALK inhibitors (ALKis) have been developed and have demonstrated their efficacy, however the best treatment strategy for ALK positive NSCLC patients has yet to be determined. Our retrospective study has investigated the outcome of 40 ALK-rearranged NSCLC patients treated with two different sequential strategies in our Institute; a “classical group”, treated with crizotinib followed by second or third generation ALKis, and the “experimental group”, treated upfront with a second generation ALK inhibitor. The primary endpoints investigated were Progression-free survival (PFS) and intracranial activity. The analysis has revealed a significant improvement in PFS (p = 0.050) in the experimental group, furthermore none of these patients developed brain metastasis. There was no statistically significant difference in OS, but all patients in the experimental group were still alive after a median follow up of 15 months. Our retrospective analysis suggests that systemic and intracranial efficacy tends to be better in the experimental group; randomized prospective studies could confirm our observations.

Response to crizotinib in advanced ALK-rearranged non-small cell lung cancers with different ALK-fusion variants

INTRODUCTION

Anaplastic lymphoma kinase (ALK) rearrangements are present in approximately 5% of non-small-cell lung cancers (NSCLCs). NSCLCs with ALK-rearrangement can be effectively treated with crizotinib. However, magnitude and duration of responses are found to be heterogeneous. This study explored the clinical efficacy of crizotinib in different ALK variants.

METHODS

Among 96 ALK-rearrangement patients treated with crizotinib, 60 patients were identified with tumor specimens that could be evaluated by next-generation sequencing (NGS). We retrospectively evaluated the efficacy of crizotinib in different ALK variants.

RESULTS

The median Progression-free survival (PFS) of the 96 ALK-rearrangement patients was 14.17 months. Among the 60 patients with NGS results, the most frequent variants were variant 3a/b (33.33%), variant 1 (23.33%) and variant 2 (15.00%). The percentage of rare EML4-ALK variants and non EML4-ALK variants were 10.00% and 18.33%. Survival analysis showed that patients with variant 2 appeared to have longer PFS than others (P = .021); also, patients with TP53 mutation seemed to have an unfavorable PFS than those with TP53 wild-type with a borderline p value (P = .068). After adjusting for other baseline characteristics, EML4-ALK variant 2 was identified as an important factor for a better PFS of crizotinib. We also found that patients with variant 3a/b had shorter duration of response to crizotinib; however, no significant difference of PFS was observed between the PFS of variant3a/b and non-v3 EML4-ALK variants.

CONCLUSIONS

Our results indicate prolonged PFS in patients with EML4-ALK variant 2.

EML4-ALK fusion variant V3 is a high-risk feature conferring accelerated metastatic spread, early treatment failure and worse overall survival in ALK+ non-small cell lung cancer

In order to identify anaplastic lymphoma kinase-driven non-small cell lung cancer (ALK⁺ NSCLC) patients with a worse outcome, who might require alternative therapeutic approaches, we retrospectively analyzed all stage IV cases treated at our institutions with one of the main echinoderm microtubule-associated protein-like 4 (EML4)-ALK fusion variants V1, V2 and V3 as detected by next-generation sequencing or reverse transcription-polymerase chain reaction (n = 67). Progression under tyrosine kinase inhibitor (TKI) treatment was evaluated both according to Response Evaluation Criteria in Solid Tumors (RECIST) and by the need to change systemic therapy. EML4-ALK fusion variants V1, V2 and V3 were found in 39%, 10% and 51% of cases, respectively. Patients with V3-driven tumors had more metastatic sites at diagnosis than cases with the V1 and V2 variants (mean 3.3 vs. 1.9 and 1.6, p = 0.005), which suggests increased disease aggressiveness. Furthermore, V3-positive status was associated with earlier failure after treatment with first and second-generation ALK TKI (median progression-free survival [PFS] by RECIST in the first line 7.3 vs. 39.3 months, p = 0.01), platinum-based combination chemotherapy (median PFS 5.4 vs. 15.2 months for the first line, p = 0.008) and cerebral radiotherapy (median brain PFS 6.1 months vs. not reached for cerebral radiotherapy during first-line treatment, p = 0.028), and with inferior overall survival (39.8 vs. 59.6 months in median, p = 0.017). Thus, EML4-ALK fusion variant V3 is a high-risk feature for ALK⁺ NSCLC. Determination of V3 status should be considered as part of the initial workup for this entity in order to select patients for more aggressive surveillance and treatment strategies.

ALK fusion variants detection by targeted RNA-next generation sequencing and clinical responses to crizotinib in ALK-positive non-small cell lung cancer

OBJECTIVES

The aim of the present study was firstly to assess in a clinical setting the yields of an amplicon-based parallel RNA sequencing (RNA-seq) assay for ALK fusion transcript variants detection in comparison with immunohistochemistry (IHC) and fluorescent in-situ hybridization (FISH) in a selected population of ALK-positive and ALK-negative non-small cell lung cancer (NSCLC) cases, and secondly to evaluate the impact of the ALK variant on crizotinib efficacy.

MATERIALS AND METHODS

The cohort used for the assessment of the RNA-seq assay comprised 53 samples initially diagnosed as being ALK-positive based on the results obtained by IHC and/or FISH, and 23 ALK-negative samples. A distinction was made between 'truly' IHC/FISH positive or 'truly' IHC/FISH negative samples, and those for which the IHC and/or FISH were equivocal (IHC) or borderline-positive (FISH).

RESULTS

On the overall population, RNA-seq sensitivity (Se) and specificity (Spe) were of 80% and 100%, respectively when IHC and FISH were combined. For the 31 'truly positive' samples, Se and Spe of 100% were reached. An ALK status could be assigned by RNA-seq in 10/10 of the equivocal and/or borderline-positive IHC/FISH cases, 2/7 IHC/FISH discordant cases. When crizotinib efficacy was evaluated according to the type of ALK variant, better clinical outcomes were observed in crizotinib-treated patients with EML4-ALK v1/v2/others variants compared to v3a/b variants.

CONCLUSION

RNA-seq detects ALK rearrangements with a high sensitivity and specificity using only 10 ng of RNA. It appears to be a promising rescue technique for non-clear-cut IHC/FISH cases and also offers a unique opportunity to identify ALK fusion variants and evaluate their predictive value for ALK inhibitors efficacy.

EML4-ALK Variants: Biological and Molecular Properties, and the Implications for Patients

Since the discovery of the fusion between EML4 (echinoderm microtubule associated protein-like 4) and ALK (anaplastic lymphoma kinase), EML4-ALK, in lung adenocarcinomas in 2007, and the subsequent identification of at least 15 different variants in lung cancers, there has been a revolution in molecular-targeted therapy that has transformed the outlook for these patients. Our recent focus has been on understanding how and why the expression of particular variants can affect biological and molecular properties of cancer cells, as well as identifying the key signalling pathways triggered, as a result. In the clinical setting, this understanding led to the discovery that the type of variant influences the response of patients to ALK therapy. Here, we discuss what we know so far about the EML4-ALK variants in molecular signalling pathways and what questions remain to be answered. In the longer term, this analysis may uncover ways to specifically treat patients for a better outcome.

Differential protein stability and clinical responses of EML4-ALK fusion variants to various ALK inhibitors in advanced ALK-rearranged non-small cell lung cancer

Background

Anaplastic lymphoma kinase (ALK) inhibition using crizotinib has become the standard of care in advanced ALK-rearranged non-small cell lung cancer (NSCLC), but the treatment outcomes and duration of response vary widely. Echinoderm microtubule-associated protein-like 4 (EML4)-ALK is the most common translocation, and the fusion variants show different sensitivity to crizotinib in vitro. However, there are only limited data on the specific EML4-ALK variants and clinical responses of patients to various ALK inhibitors.

Patients and methods

By multiplex reverse-transcriptase PCR, which detects 12 variants of known EML4-ALK rearrangements, we retrospectively determined ALK fusion variants in 54 advanced ALK rearrangement-positive NSCLCs. We subdivided the patients into two groups (variants 1/2/others and variants 3a/b) by protein stability and evaluated correlations of the variant status with clinical responses to crizotinib, alectinib, or ceritinib. Moreover, we established the EML4-ALK variant-expressing system and analyzed patterns of sensitivity of the variants to ALK inhibitors.

Results

Of the 54 tumors analyzed, EML4-ALK variants 3a/b (44.4%) was the most common type, followed by variants 1 (33.3%) and 2 (11.1%). The 2-year progression-free survival (PFS) rate was 76.0% [95% confidence interval (CI) 56.8-100] in group EML4-ALK variants 1/2/others versus 26.4% (95% CI 10.5-66.6) in group variants 3a/b (P = 0.034) among crizotinib-treated patients. Meanwhile, the 2-year PFS rate was 69.0% (95% CI 49.9-95.4) in group variants 1/2/others versus 32.7% (95% CI 15.6-68.4) in group variants 3a/b (P = 0.108) among all crizotinib-, alectinib-, and ceritinib-treated patients. Variant 3a- or 5a-harboring cells were resistant to ALK inhibitors with >10-fold higher half maximal inhibitory concentration in vitro.

Conclusion

Our findings show that group EML4-ALK variants 3a/b may be a major source of ALK inhibitor resistance in the clinic. The variant-specific genotype of the EML4-ALK fusion allows for more precise stratification of patients with advanced NSCLC.

Circulating Tumor Cells with Aberrant ALK Copy Number Predict Progression-Free Survival during Crizotinib Treatment in ALK-Rearranged Non-Small Cell Lung Cancer Patients

The duration and magnitude of clinical response are unpredictable in ALK-rearranged non-small cell lung cancer (NSCLC) patients treated with crizotinib, although all patients invariably develop resistance. Here, we evaluated whether circulating tumor cells (CTC) with aberrant ALK-FISH patterns [ALK-rearrangement, ALK-copy number gain (ALK-CNG)] monitored on crizotinib could predict progression-free survival (PFS) in a cohort of ALK-rearranged patients. Thirty-nine ALK-rearranged NSCLC patients treated with crizotinib as first ALK inhibitor were recruited prospectively. Blood samples were collected at baseline and at an early time-point (2 months) on crizotinib. Aberrant ALK-FISH patterns were examined in CTCs using immunofluorescence staining combined with filter-adapted FISH after filtration enrichment. CTCs were classified into distinct subsets according to the presence of ALK-rearrangement and/or ALK-CNG signals. No significant association between baseline numbers of ALK-rearranged or ALK-CNG CTCs and PFS was observed. However, we observed a significant association between the decrease in CTC number with ALK-CNG on crizotinib and a longer PFS (likelihood ratio test, P = 0.025). In multivariate analysis, the dynamic change of CTC with ALK-CNG was the strongest factor associated with PFS (HR, 4.485; 95% confidence interval, 1.543-13.030, P = 0.006). Although not dominant, ALK-CNG has been reported to be one of the mechanisms of acquired resistance to crizotinib in tumor biopsies. Our results suggest that the dynamic change in the numbers of CTCs with ALK-CNG may be a predictive biomarker for crizotinib efficacy in ALK-rearranged NSCLC patients. Serial molecular analysis of CTC shows promise for real-time patient monitoring and clinical outcome prediction in this population. Cancer Res; 77(9); 2222-30. ©2017 AACR.

Is there a benefit of first- or second-line crizotinib in locally advanced or metastatic anaplastic lymphoma kinase-positive non-small cell lung cancer? a meta-analysis

BACKGROUND

Crizotinib show a promising efficacy in patients with anaplastic lymphoma kinase (ALK)-positive non-small cell lung cancer (NSCLC). However, differences in efficacy for first- and second-line crizotinib are unclear.

RESULTS

The pooled overall response rate and progression-free survival were 65% and 9.38 months, respectively. In the subgroup analysis, first-line crizotinib showed a higher trend of overall response rate and longer trend of progression-free survival although there was no statistical difference between first-line and second-line crizotinib (74%, 11.28 months vs. 65%, 8.12 months, respectively; fixed effects model). Moreover, overall response rate between Asians and Caucasians were similar (67% and 66%, respectively; fixed effects model).

MATERIALS AND METHODS

A comprehensive search of MEDLINE, EMBASE, WEB OF SCIENCE and the COCHRANE databases from their inception to February 2016 was performed to identify clinical trials in English-language journals. Pooled overall response rate, progression-free survival and differences between first- and second-line crizotinib were estimated. Moreover, overall response rate between Asians and Caucasians were also estimated.

CONCLUSIONS

First-line crizotinib may more effective than second-line crizotinib for patients with locally advanced or metastatic ALK-positive NSCLC.