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Department of Medical Oncology, Lung Cancer and Gastrointestinal Unit, Hunan Cancer Hospital/The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, People’s Republic of China
Department of Medical Oncology, Lung Cancer and Gastrointestinal Unit, Hunan Cancer Hospital/The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, People’s Republic of China
Department of Medical Oncology, Lung Cancer and Gastrointestinal Unit, Hunan Cancer Hospital/The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, People’s Republic of China
Department of Medical Oncology, Lung Cancer and Gastrointestinal Unit, Hunan Cancer Hospital/The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, People’s Republic of China
Department of Medical Oncology, Second Chest Cancer Unit, Hunan Cancer Hospital/The Affiliated Cancer Hospital of Xiangya School of Medicine, Changsha, People’s Republic of China
Department of Medical Oncology, Lung Cancer and Gastrointestinal Unit, Hunan Cancer Hospital/The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, People’s Republic of China
Department of Medical Oncology, Lung Cancer and Gastrointestinal Unit, Hunan Cancer Hospital/The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, People’s Republic of China
Department of Medical Oncology, Lung Cancer and Gastrointestinal Unit, Hunan Cancer Hospital/The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, People’s Republic of China
Department of Medical Oncology, Lung Cancer and Gastrointestinal Unit, Hunan Cancer Hospital/The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, People’s Republic of China
Department of Medical Oncology, Lung Cancer and Gastrointestinal Unit, Hunan Cancer Hospital/The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, People’s Republic of China
Department of Medical Oncology, Lung Cancer and Gastrointestinal Unit, Hunan Cancer Hospital/The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, People’s Republic of China
Department of Medical Oncology, Lung Cancer and Gastrointestinal Unit, Hunan Cancer Hospital/The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, People’s Republic of China
Corresponding author. Address for correspondence: Nong Yang, MD, Department of Medical Oncology, Lung Cancer and Gastrointestinal Unit, Hunan Cancer Hospital/The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha 410013, People’s Republic of China.
Department of Medical Oncology, Lung Cancer and Gastrointestinal Unit, Hunan Cancer Hospital/The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, People’s Republic of China
During nonreciprocal/reciprocal translocation process, 5′-anaplastic lymphoma kinase (ALK) sometimes gets retained in the genome and is detectable by next-generation sequencing; however, no study has investigated its clinical significance. Our study aimed to assess the impact of harboring 5′-ALK on the efficacy of crizotinib.
Methods
A total of 150 patients with next-generation sequencing–identified ALK-rearranged NSCLC from March 2014 to July 2018 at the Hunan Cancer Hospital were enrolled in this study. The efficacy of crizotinib as first-line therapy was evaluated in 112 patients according to the retention of 5′-ALK.
Results
Among the 150 patients with NSCLC, nonreciprocal/reciprocal translocation was detected in 18.7% (28 of 150), and 3′-ALK fusion alone was detected in 81.3% (122 of 150). Among the 112 patients who received first-line crizotinib, 89 had 3′-ALK fusion alone (79 echinoderm microtubule associated protein-like 4 [EML4]-ALK and 10 non–EML4-ALK), and 23 had nonreciprocal/reciprocal ALK translocation. Among the patients with nonreciprocal/reciprocal ALK translocation, three patients harbored dual concurrent 3′-ALK fusions. Patients with nonreciprocal/reciprocal ALK translocation had higher incidence of brain metastasis at baseline than those with 3′-ALK fusion alone (39.1% versus 13.4%, p = 0.028). Crizotinib-treated patients with nonreciprocal/reciprocal ALK translocation had significantly shorter median progression-free survival (PFS) compared with patients carrying 3′-ALK fusion alone (6.1 m versus 12.0 m, p = 0.001) or with EML4-ALK fusion alone (6.1 m versus 12.6 m, p = 0.001). Multivariate analysis revealed that harboring nonreciprocal/reciprocal ALK translocation was an independent predictor of worse PFS for crizotinib-treated ALK-rearranged NSCLC (p = 0.0046).
Conclusions
Presence of nonreciprocal/reciprocal ALK translocation was predictive for worse PFS and greater likelihood of baseline brain metastases in patients with ALK-rearranged NSCLC who received first-line crizotinib.
Echinoderm microtubule-associated protein-like 4 (EML4) is the most common ALK fusion partner, which was first described in 2007 as a reciprocal inversion between EML4 and ALK resulting in EML4-ALK and ALK-EML4 fusions.
Distribution of ALK fusion variants and correlation with clinical outcomes in Chinese patients with non-small cell lung cancer treated with crizotinib.
With the development of gene-sequencing technologies, more non–EML4-ALK fusions are being identified, with their responses to crizotinib reported in several case reports.
Detection of ALK translocation in non-small cell lung carcinoma (NSCLC) and its clinicopathological significance using the Ventana immunohistochemical staining method: a single-center large-scale investigation of 1, 504 Chinese Han patients.
Sequential ALK inhibitor treatment benefits patient with leptomeningeal metastasis harboring non-EML4-ALK rearrangements detected from cerebrospinal fluid: a case report.
Crizotinib is the first tyrosine kinase inhibitor approved by the US Food and Drug Administration in 2011 for ALK-rearranged NSCLCs, and its efficacy has been comprehensively verified in a series of clinical trials.
Despite dramatic responses to crizotinib therapy, the response duration of patients treated with crizotinib varies and emerging data suggest that the EML4-ALK breakpoint variants or ALK fusion partners affect clinical outcomes.
Nevertheless, the clinical outcomes of patients whose tumors retained nonreciprocal/reciprocal ALK translocation remain unexplored. In this study, we investigated the prognostic impact of nonreciprocal/reciprocal ALK rearrangements in patients who receive first-line crizotinib.
Materials and Methods
Patients
We retrospectively screened 2612 lung cancers that were analyzed by next-generation sequencing (NGS) from March 2014 to July 2018 at the Hunan Cancer Hospital. A total of 150 patients were identified with ALK-rearranged advanced NSCLC, and 112 of them received crizotinib as first-line treatment (Fig. 1). All the 112 patients met the following criteria: (1) pathologically confirmed NSCLC, (2) ALK rearrangements identified by NGS, and (3) treatment with crizotinib in the first-line setting. NGS results of all 150 patients were analyzed; however, 38 patients did not meet the third inclusion criteria and were excluded from further analysis. Hence, clinical outcomes were analyzed in 112 patients who received first-line crizotinib. Written informed consent was obtained from all the patients before inclusion to this study in 2018. Approval was also obtained from Hunan Cancer Hospital Institutional Review Board Committee.
DNA isolated from tissue biopsy or blood samples obtained from all the patients were sequenced on a Nextseq 500 (Illumina, San Diego, CA) with paired-end reads with target sequencing depth of 1000× and 10,000× for tissue and plasma samples, respectively, using commercially available panel targeting 168 genes (Supplementary Table 1) (Burning Rock Biotech, Guangzhou, People’s Republic of China).
The capture probes for detecting the ALK fusions were designed to interrogate the intronic regions of ALK, whereas no capture probe was designed to target intronic regions of the fusion partner, including EML4. Thus, the probe design does not affect the detection frequencies for EML4-ALK and non–EML4-ALK.
Evaluation of Crizotinib Efficacy
Crizotinib was orally administered with a dose of 250 mg twice daily until evaluation of progressive disease (PD) or unacceptable toxicity. Patients who experienced toxicity were managed by dose reduction or discontinuation as decided by their physicians-in-charge. The best responses were assessed according to the Response Evaluation Criteria in Solid Tumors version 1.1.
All patients underwent radiologic imaging every 8 weeks to qualify for continuation of crizotinib therapy. The overall response rate (ORR) was calculated as the total percentage of patients with complete response or partial response. Progression-free survival (PFS) was measured from the start of crizotinib administration until the date of PD. Brain metastases were regularly monitored by magnetic resonance imaging (MRI) or computed tomography (CT) in a routine follow-up every 2 months. Each image was independently evaluated by two radiologists. The data cutoff date was March 31, 2019.
Statistical Analysis
All the statistical analyses included in this study were performed with Statistical Product and Service Solutions (version 18). The comparisons of baseline characteristics between different subgroups were conducted with the chi-square or Fisher exact test. The survival probabilities were estimated using the Kaplan-Meier method and compared with the log-rank test. Multivariate data analysis was performed using Cox proportional-hazard regression model. The p values less than 0.05 were considered to be statistically significant.
Results
Patient Characteristics
We retrospectively reviewed all the 112 patients who received crizotinib as first-line treatment (Table 1). The median age was 50.5 years (range, 28–71). A total of 65 patients were women (58%), and 81 patients were never smokers (72%). Histologic examination revealed that 105 patients had adenocarcinoma, two had adenosquamous carcinoma, and five had tumors not specified. The baseline characteristics between these groups were compared, and no significant differences were observed in age, sex, smoking history, Eastern Cooperative Oncology Group performance status, and pathologic classification. No significant differences were observed in baseline clinical characteristics between patients in groups except for brain metastasis (p = 0.049) (Table 1).
Table 1Baseline Characteristics of the 112 Patients With ALK-Rearranged NSCLC Who Received First-Line Crizotinib Therapy
Among the 2612 consecutive patients with NSCLC screened, ALK fusion was detected by NGS in 150 patients, revealing an overall mutation rate of 5.7%. Table 2 summarizes the distribution of the ALK rearrangements detected in these 150 patients. Most of the patients (104 of 150, 69.3%) had single EML4-ALK rearrangement, whereas 18 (12.0%) had a single non–EML4-ALK rearrangement, and 28 (18.7%) had nonreciprocal/reciprocal ALK translocation (Table 2). Most of the non–EML4-ALK fusions (13 of 17, 76.5%) detected in our cohort were previously unreported in literature and in COSMIC (Table 2). The nonreciprocal/reciprocal ALK in our cohort was observed as harboring concurrent ALK fusions with at least one 3′-ALK fusion and one 5′-ALK. The frequency of nonreciprocal/reciprocal ALK translocation from our cohort was consistent with the two NSCLC sequencing data sets from Guangzhou and Shanghai in People’s Republic of China (Supplementary Table 2). Among the 150 patients, the most common EML4-ALK variant was 3a/b detected in 47.0% of the patients (62 of 132), followed by variant 1, variant 2, variant 5a/b, and variant 7, detected in 39, 13, 12, and four patients, respectively (Table 3). The EML4-ALK variant 3a/b was the most common in patients with single EML4-ALK fusion (n = 47, 45.2%) and those with nonreciprocal/reciprocal ALK translocation (n = 15, 53.6%) (Table 3). We found no relationship between the EML4-ALK variants (variants 1, 2, and 3) and the retention of nonreciprocal/reciprocal fusions (p = 1) (Supplementary Fig. 1). In addition, we identified two EML4-ALK variants that have not been previously reported in PubMed and COSMIC (E7; A20 and E3; A20) (Supplementary Fig. 2). Because most of the samples sequenced from the patients were tissue biopsy samples, the allele frequencies of the nonreciprocal/reciprocal translocation had a median of 24.40% and 18.31% for EML4-ALK and 5′-ALK, respectively. The allelic frequencies of the fusions detected from the 28 patients with nonreciprocal/reciprocal ALK translocation are listed in Table 4.
Table 2Distribution of ALK Rearrangements Identified From the 150 Patients
ALK Fusions Identified in 112 Patients Who Received First-Line Crizotinib
We further analyzed our data to investigate whether the ALK alleles fused to non-EML4 genes retained the ALK kinase domain. For patients with nonreciprocal/reciprocal ALK fusions, most of the nonreciprocal ALK occurred through additional inversion, duplication, or deletion events. Most of these non-EML4 genes (16 of 21, 76.1%) was located on the same chromosome as ALK and EML4, with the exception of ALK-SP3 located on the q arm of chromosome 2; the other 15 genes were located on the p arm of chromosome 2, whereas the remaining four genes, detected from six patients, were located on different chromosomes (Supplementary Table 3). In rare cases, such as those identified in three patients with dual fusions in our cohort, an additional chromosomal translocation occurred, thereby creating a fusion event between ALK and a gene located on a different chromosome (Supplementary Table 3). Most of the patients with single non–EML4-ALK fusion partner (6 of 10, 60%) harbored 3′-ALK fusions that retained the ALK kinase domain; all the patients with nonreciprocal/reciprocal ALK translocation (n = 23) had at least one ALK fusion with ALK at the 3′-end, which was primarily EML4-ALK, and a reciprocal/nonreciprocal translocation product having the 5′-end of ALK that did not contain the DNA sequence encoding the ALK kinase domain. Interestingly, all three patients identified with dual ALK fusion harbored an EML4-ALK fusion and a non-EML4 partner fused to the 3′-end of ALK, including CDC42EP3-ALK (C(3′-UTR); A20), MTA3-ALK (M6; A20), and TSPYL6-ALK (A6; A20), and 5′-ALK, including ALK-DIRC3-AS1 (A19; intergenic), ALK-SP3 (A19; intergenic), and ALK-ABCG8 (A19; A5) (patients no. 6, no. 21, and no. 27) (Supplementary Table 3).
Among the 112 patients who received first-line crizotinib therapy, 71% (n = 79) had single EML4-ALK fusion, 21% (n = 23) had nonreciprocal/reciprocal ALK translocation, and 9% (n = 10) had a single non-EML4 fusion partner. We also compared the baseline genotype of the patients with single EML4-ALK fusion, nonreciprocal/reciprocal ALK translocation, and single non–EML4-ALK fusion. The most common concurrent mutation was in TP53 identified in 13.9% of the patients with single EML4-ALK fusion (11 of 79) and 13.0% in patients with nonreciprocal/reciprocal ALK translocation (3 of 23). TP53 mutation was not detected among the 10 patients with non–EML4-ALK fusion (Supplementary Fig. 3).
Among the 112 patients, 40 also had ALK expression assessment using immunohistochemistry (IHC) (Ventana, Roche). Consistent with other published data,
the concordance rate between NGS and Ventana IHC in our cohort was 85%, with only six patients identified by NGS as having at least one EML4-ALK fusion but were negative with Ventana IHC. All the six patients responded to first-line crizotinib therapy.
Response Rates With Crizotinib
All the 112 patients who received crizotinib as first-line treatment were evaluable for treatment efficacy and had an overall ORR of 76.8% (86 of 112) (95% confidence interval [CI]: 67.9%–84.2%). Meanwhile, on the basis of fusion partners, the ORR of patients with EML4-ALK fusion alone and patients with nonreciprocal/reciprocal ALK translocation was 78.5% (67.8%–86.9%) and 69.6% (47.1%–86.8%), respectively (p = 0.709) (Supplementary Table 4). Moreover, to compare the treatment response rates of patients with 3′-ALK alone or nonreciprocal/reciprocal ALK translocation, we grouped the 79 patients with EML4-ALK fusion alone and the 10 patients with non–EML4-ALK fusion alone together as 3′-ALK fusion alone (n = 89). The ORR of the patients with 3′-ALK fusion alone and patients with nonreciprocal/reciprocal ALK translocation was 78.7% (68.7%–86.6%) and 69.6% (47.1%–86.8%), respectively (p = 0.743) (Supplementary Table 4). Supplementary Table 5 summarizes the clinical outcome of the patients with non–EML4-ALK fusions treated with first-line crizotinib.
Efficacy of Crizotinib in Patients With 3'-ALK Fusion Alone Versus Nonreciprocal/Reciprocal ALK Translocation
We next assessed the impact of nonreciprocal/reciprocal ALK translocation on the PFS outcome with first-line crizotinib. The overall median PFS (mPFS) of the 112 patients who received first-line crizotinib was 11.0 months (95% CI: 8.0–14.1 mo) (Supplementary Table 4) (Fig. 2A). Patients with nonreciprocal/reciprocal ALK translocation (n = 23, 6.1 mo [95% CI: 5.0–11.0 mo]) have significantly shorter mPFS compared with patients with 3′-ALK fusion alone (n = 89, 12.0 mo [95% CI: 11.0–20.0 mo], p = 0.001; Fig. 2B). Meanwhile, the mPFS for the patients with nonreciprocal/reciprocal ALK translocation (n = 23, 6.1 mo [95% CI: 5.0–11.0 mo]) was significantly inferior than the patients with EML4-ALK fusion alone (n = 79, 12.6 mo [95% CI: 11.0–24.0 mo], p = 0.001; Fig. 2C).
Figure 2Progression-free survival (PFS) of patients with nonreciprocal/reciprocal translocations was significantly shorter. Kaplan–Meier curves for (A) 112 crizotinib-treated patients with anaplastic lymphoma kinase (ALK)-rearranged NSCLC; (B) patients with 3′-ALK fusion alone (both echinoderm microtubule-associated protein-like 4 [EML4] and non-EML4] and nonreciprocal/reciprocal ALK translocation (12.0 versus 6.1 mo, p = 0.001); (C) patients with EML4-ALK fusion alone and nonreciprocal/reciprocal ALK translocations (12.6 versus 6.1 mo, p = 0.001). (D and E) Patients with nonreciprocal/reciprocal ALK translocations who presented with either brain metastasis (D) or nonbrain metastasis (E) have significantly shorter progression-free survival than patients with EML4-ALK fusion alone.
We investigated the pattern of brain metastasis among the ALK fusions of the patients at baseline. First, we compared the number of patients according to the imaging method used to evaluate brain involvement during enrollment. Among the patients with the EML4-ALK fusion alone (n = 79), 26 and 53 patients underwent head CT with contrast and MRI, respectively. Among the patients with nonreciprocal/reciprocal ALK translocation (n = 23), eight and 15 patients underwent CT and MRI, respectively. Among the patients with non–EML4-ALK fusion alone (n = 10), three and seven patients underwent CT and MRI, respectively. On the basis of the detection method used, there was no significant difference among the groups (Supplementary Table 6). Nevertheless, the patients with nonreciprocal/reciprocal ALK translocation (9 of 23, 39.1%) had a significantly higher incidence of brain metastasis at baseline as compared with those with single 3′-ALK fusion with either EML4 or non-EML4 fusions (12 of 89, 13.4%; p = 0.028). Moreover, the patients with nonreciprocal/reciprocal ALK translocation tend to present with brain metastasis (9 of 23, 39.1%) more frequently than the patients with the EML4-ALK fusion alone (12 of 79, 15.2%; p = 0.049). Among the patients who presented with brain metastasis at baseline, those with nonreciprocal/reciprocal ALK translocation had a significantly shorter PFS as compared with those with 3′-ALK fusion alone (4.0 mo [95% CI: 2.2–5.7 mo] versus 11.0 mo [95% CI: 2.9–21.3 mo]; p = 0.0412; Fig. 2D). Consistently, patients with nonreciprocal/reciprocal ALK translocation who presented with metastasis at sites other than the brain with no brain metastasis at baseline also had significantly shorter PFS (6.6 mo [95% CI: 5.7–7.2 mo] versus 12.0 mo [95% CI: 10.1–15.1 mo]; p = 0.0204; Fig. 2E). Multivariate analysis of clinical variables, including age, sex, brain metastasis, and harboring nonreciprocal/reciprocal ALK translocation, revealed that harboring nonreciprocal/reciprocal translocation was an independent predictor of worse PFS for crizotinib-treated ALK-rearranged NSCLC (p = 0.0046) (Table 5).
Table 5Multivariate Analysis for Progression-Free Survival
Patterns of Disease Progression and Subsequent Treatment
Among the 112 patients treated with crizotinib, 68 (55.7%) had PD during the follow-up period. Of them, 20 (29.4%), 14 (20.6%), and 34 (50.0%) patients progressed with metastasis in the brain, extrathoracic sites, and intrathoracic sites, respectively. We found that among the patients with the EML4-ALK fusion alone (n = 79), 43 were evaluated with PD, of which 32.6% (14 of 43) developed brain metastasis at failure of crizotinib therapy. Among the 19 patients with nonreciprocal/reciprocal ALK translocation who were evaluated with PD, 26.3% (5 of 19) developed brain metastasis. Meanwhile, among the six patients with the non–EML4-ALK fusion alone evaluated with PD, only one (1 of 6, 16.7%) developed brain metastasis. No significant difference was found among the three groups for disease progression in the brain, extrathoracic, and intrathoracic sites (Supplementary Table 7).
After the failure of crizotinib in these 68 patients, 33.8% (23 of 60) of them received crizotinib combined with radiotherapy, 20.5% (14 of 68) received ceritinib, 11.8% (8 of 68) received chemotherapy, 7.4% (8 of 68) were enrolled in other ALK-tyrosine kinase inhibitor clinical trials, and 7.4% (5 of 68) received alectinib. A total of 10 patients (10 of 68, 14.7%) did not receive further treatment. Among the patients who received alectinib after failure of crizotinib, three who harbored nonreciprocal/reciprocal ALK fusions also did not benefit from alectinib therapy, with two evaluated with PD after 1 month of therapy, whereas one had disease progression within 3 months of therapy.
Patients With Dual ALK Fusions With Concurrent 5′-ALK
Among the patients with nonreciprocal/reciprocal ALK translocation, three were detected with dual ALK fusions. Patient no. 6 who harbored EML4-ALK (E6; A20), CDC42EP3-ALK (C(3′-UTR); A20), and ALK-DIRC3-AS1 (A19; intergenic) did not benefit from either first-line crizotinib or second-line alectinib with best response evaluated as PD after 1 month of therapy. She succumbed to her disease shortly after with an overall survival of 3 months. Patient no. 21 who harbored EML4-ALK (E13; A20), MTA3-ALK (M6; A20), and ALK-SP3 (A19; intergenic) had stable disease with crizotinib, which lasted for 3 months. He received alectinib as second-line therapy without benefit. He was administered with a combination of chemotherapy and immunotherapy and achieved partial response. His treatment is still ongoing as of December 31, 2019. Meanwhile, patient no. 27 who harbored EML4-ALK (E6; A20), TSPYL6-ALK (A6; A20), and ALK-ABCG8 (A19; A5) achieved partial response with crizotinib therapy lasting for 6.5 months. He received second-line alectinib therapy lasting for 3 months and is currently receiving a combination of chemotherapy and immunotherapy as of December 31, 2019. Their treatment details are summarized in Supplementary Table 4.
Discussion
In this hypothesis-generating study, we demonstrate the negative prognostic impact of nonreciprocal/reciprocal ALK translocation in patients with ALK-rearranged NSCLC who received first-line crizotinib. Moreover, the patients with nonreciprocal/reciprocal ALK translocation were more likely to present with brain metastases at diagnosis than patients with the 3′-ALK fusion alone. Previous work has assessed the variability of crizotinib efficacy of patients with various EML4-ALK fusion variants and ALK fusions with non-EML4 partners
; however, none has investigated the clinical relevance of retaining the 5′-ALK DNA from nonreciprocal/reciprocal translocation process. To the best of our knowledge, our study was the first to assess the prognostic impact of nonreciprocal/reciprocal translocation and the fate of 5′-ALK DNA on the efficacy of crizotinib. The ORR of our cohort was 76.8% (86 of 112), with no statistical difference in response rates among the patients with single fusion or nonreciprocal/reciprocal translocation who received crizotinib in the first-line setting. On the basis of the absence of the ALK tyrosine kinase domain of the 5′-ALK, these ALK nonreciprocal/reciprocal translocation products would be nonfunctional in terms of tyrosine kinase activity and would not affect inhibitor response. Nevertheless, the patients who harbored nonreciprocal/reciprocal ALK translocation and received crizotinib in the first-line setting have significantly shorter PFS than those with 3′-ALK fusion alone, suggesting prognostic implications of the concurrent 5′-ALK. These events may be part of a more complex chromoanagenesis phenomenon, such as chromothripsis or chromoplexy.
These complex events might be the molecular mechanism underlying the presence of dual ALK fusions in three patients, including one EML4-ALK and one non-EML4 fusion with 3′-ALK and retention of 5′-ALK. These observations indicate that specific combinations bring about differential treatment responses and do not fit in a one-size-fit-all pattern. It is critical to understand not just the actionable mutations but also the concurrent mutations and retention of certain DNA fragments that could contribute to the treatment response and prognosis of the patient.
It would be interesting to know how these 5′-ALK DNA could contribute to the poor prognosis of patients who harbor them. Further mechanistic studies are warranted to elucidate their intracellular function. Moreover, our study is also limited by the lack of RNA samples derived from patients that could provide information on whether the 5′-ALK DNA are transcribed into RNA. There were also other limitations with our study, including potential patient selection bias and limited sample size. Owing to the retrospective nature of our study, some information, such as overall survival, was not available for some patients, whereas some patients are still being followed up. Accordingly, our findings would benefit from validation in a separate cohort with a larger sample size.
In conclusion, we reported that nonreciprocal/reciprocal ALK translocations were associated with poor survival outcomes with first-line crizotinib compared with 3′-ALK fusion alone. In addition, patients with nonreciprocal/reciprocal ALK translocation more often present with brain metastases.
Acknowledgments
This work was supported by grants from the National Natural Science Foundation (No. 81401902 to Yongchang Zhang and No. 81501992 to Rui Guan) and the Natural Science Foundation of Hunan Province (2018RS3106 to Yongchang Zhang, 2018JJ2238 to Yongchang Zhang, and 2017SK2134 to Nong Yang). The authors thank all the patients who participated in this study. The authors thank Ms. Dandan Hu and Dr. Rui Guan for providing their technical support and discussions throughout the study. The authors also thank Xinru Mao of Burning Rock Biotech for analyzing and interpreting the genomic data.
Figure S3Baseline mutation profile of the cohort. Colored bar at the bottom indicates the ALK rearrangement of the cohort, red refers to patients with EML4-ALK fusion alone; blue refers to patients with nonreciprocal/reciprocal ALK translocations; and green refers to patients with non-EML4 ALK fusion alone. Each column represents a patient and each row represents a gene. Number on the left represents the percentage of patients with mutations in a specific gene. Top plot represents the overall number of mutations a patient carried. Different colors denote different types of mutation.
Distribution of ALK fusion variants and correlation with clinical outcomes in Chinese patients with non-small cell lung cancer treated with crizotinib.
Detection of ALK translocation in non-small cell lung carcinoma (NSCLC) and its clinicopathological significance using the Ventana immunohistochemical staining method: a single-center large-scale investigation of 1, 504 Chinese Han patients.
Sequential ALK inhibitor treatment benefits patient with leptomeningeal metastasis harboring non-EML4-ALK rearrangements detected from cerebrospinal fluid: a case report.
When EML4-ALK fusion generated from intrachromosomal inversion was first identified in NSCLC in 2007, the reciprocal translocation ALK-EML4 was also identified.1 Fluorescence in situ hybridization (FISH) became the first U.S. Food and Drug Administration (FDA)–approved companion diagnostic platform to identify ALK rearrangement for clinical purposes in 2011.2 The criteria for ALK positivity was either the presence of ALK break-apart signals or the presence of isolated 3′ ALK signals present in more than 15% of the cells examined (minimum of 50 cells).
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