Brain Exposure to the Macrocyclic ALK Inhibitor Zotizalkib is Restricted by ABCB1, and Its Plasma Disposition is Affected by Mouse Carboxylesterase 1c.

Zotizalkib (TPX-0131), a fourth-generation macrocyclic anaplastic lymphoma kinase (ALK) inhibitor, is designed to overcome resistance due to secondary ALK mutations in non-small cell lung cancer (NSCLC). We here evaluated the pharmacokinetic roles of the ABCB1 (P-gp/MDR1) and ABCG2 (BCRP) efflux transporters, OATP1 influx transporters and the metabolizing enzymes CES1 and CYP3A in plasma and tissue disposition of zotizalkib after oral administration in relevant mouse models. Zotizalkib was efficiently transported by hABCB1 in vitro. In vivo, a significant ∼9-fold higher brain-to-plasma ratio was observed in Abcb1a/b-/- and Abcb1a/b;Abcg2-/- compared to wild-type mice. No change in brain disposition was observed in Abcg2-/- mice, suggesting that mAbcb1a/b markedly restricts the brain accumulation of zotizalkib. ABCB1-mediated efflux of zotizalkib was completely inhibited by elacridar, a dual ABCB1/ABCG2 inhibitor, increasing brain exposure without any signs of acute CNS-related toxicities. In Oatp1a/b-/- mice, no marked changes in plasma exposure or tissue-to-plasma ratios were observed, indicating that zotizalkib is not a substantial in vivo substrate for mOatp1a/b. Zotizalkib may further be metabolized by CYP3A4 but only noticeably at low plasma concentrations. In Ces1-/- mice, a 2.5-fold lower plasma exposure was seen compared to wild-type, without alterations in tissue distribution. This suggests increased plasma retention of zotizalkib by binding to the abundant mouse plasma Ces1c. Notably, the hepatic expression of human CES1 did not affect zotizalkib plasma exposure or tissue distribution. The obtained pharmacokinetic insights may be useful for the further development and optimization of therapeutic efficacy and safety of zotizalkib and related compact macrocyclic ALK inhibitors.

Pan-HER inhibitors overcome lorlatinib resistance caused by NRG1/HER3 activation in ALK-rearranged lung cancer.

Lorlatinib, a third-generation anaplastic lymphoma kinase (ALK)-tyrosine kinase inhibitor (TKI) with a broad coverage against ALK mutations, has demonstrated dramatic effects in patients with ALK-rearranged lung cancer. The mechanisms of acquired resistance to lorlatinib by secondary ALK compound mutations have recently been reported; however, resistance mechanisms other than secondary mutations remain unclear. Here, we investigated the molecular mechanisms of the acquired resistance in ALK-rearranged lung cancer cells in vitro. We established two different lorlatinib-resistant ALK-rearranged lung cancer cell lines (H3122LR and A925LLR) via long-term administration of lorlatinib. These resistant cells did not harbor the secondary ALK mutations and showed cross-resistance to the other kinds of ALK-TKIs (crizotinib or alectinib) compared with the parental cells; however, these resistant cells overexpressed the phosphorylated human epidermal growth factor receptor 3 (HER3) protein and the ligand of HER3 (neuregulin 1; NRG1). Pharmacological inhibition of HER3 with pan-HER inhibitors or genetic knockdown of HER3 with siRNA resensitized H3122LR and A925LLR cells to lorlatinib in vitro, indicating that H3122LR and A925LLR acquired resistance by NRG1/HER3 activation. These findings demonstrated that targeting NRG1/HER3 is a potential novel therapeutic option for lorlatinib-resistant ALK-rearranged lung cancer.

Discovery and preclinical evaluations of WX-0593, a novel ALK inhibitor targeting crizotinib-resistant mutations.

ALK gene rearrangements are oncogenic drivers in approximately 5% of NSCLC. Crizotinib, a first generation ALK inhibitor, is widely prescribed for ALK-positive NSCLC in clinic. Resistance to crizotinib and other ALK inhibitors has been problematic. Addressing resistance, here we describe discovery and development of a novel, proprietary spirocyclic diamine-substituted aryl phosphine oxide series of inhibitors, which led to the identification of WX-0593 (16a) as a potent ALK inhibitor. WX-0593 inhibited the activity of both wild type and resistant mutants of ALK in vitro, showed strong antitumor activity in a crizotinib-resistant mouse PDX model. WX-0593 is currently under development in phase II/III clinical trials.

Design and synthesis of boron-containing ALK inhibitor with favorable in vivo efficacy.

ALK is an attractive therapeutic target for the treatment of non-small cell lung cancer. As an emerging element in medicinal chemistry, boron has achieved great success in the discovery of antitumor drugs and antibacterial agents. Through construction of a BCC (boron-containing compound) compound library and broad kinase screening, we found the ALK inhibitor hit compound 10a. Structural optimization by CADD and isosterism revealed that lead compound 10k has improved activity (ALKL1196M IC50 = 8.4 nM, NCI-H2228 cells IC50 = 520 nM) and better in vitro metabolic stability (human liver microsomes, T1/2 = 238 min). Compound 10k showed good in vivo efficacy in a nude mouse NCI-H2228 lung cancer xenograft model with a TGI of 52 %. Molecular simulation analysis results show that the hydroxyl group on the oxaborole forms a key hydrogen bond with Asn1254 or Asp1270, and this binding site provides a new idea for drug design. This is the first publicly reported lead compound for a boron-containing ALK inhibitor.

Indirect comparisons of brigatinib and alectinib for front-line ALK-positive non-small-cell lung cancer.

Aim: To conduct an indirect treatment comparison (ITC) of the relative efficacy of brigatinib and alectinib for progression-free survival in people with tyrosine kinase inhibitor (TKI)-naive ALK-positive non-small-cell lung cancer (NSCLC). Methods: Final aggregate and patient-level data from the ALTA-1L trial comparing brigatinib to crizotinib and published aggregate data from ALEX (comparing alectinib to crizotinib) were contrasted using Bucher ITC and matching-adjusted indirect comparisons (MAICs). Results: No statistically significant differences were identified between brigatinib and alectinib in reducing the risk of disease progression overall and in patients with baseline central nervous system metastases. Conclusion: Brigatinib appeared similar to alectinib in reducing risk of disease progression for people with TKI-naive ALK-positive NSCLC.

Patients with advanced non-small-cell lung cancer (NSCLC) who have a genetic marker called rearrangement in the anaplastic lymphoma kinase, or ALK-positive disease, are treated with targeted medications taken by mouth. Two medications, alectinib and brigatinib, are both considered first-line treatment for these patients but have not been compared head-to-head. Recently, updated clinical trial results were published for these medications. The present study utilized these updated results and advanced statistical tests to indirectly compare the effectiveness of the two treatments to help guide clinical treatment choices. Results showed brigatinib and alectinib have a similar magnitude of effect in decreasing the risk of a patient with ALK-positive NSCLC developing worsening disease.

Alectinib for relapsed or refractory anaplastic lymphoma kinase-positive anaplastic large cell lymphoma: An open-label phase II trial.

Anaplastic lymphoma kinase (ALK) inhibition is expected to be a promising therapeutic strategy for ALK-positive malignancies. We aimed to examine the efficacy and safety of alectinib, a second-generation ALK inhibitor, in patients with relapsed or refractory ALK-positive anaplastic large cell lymphoma (ALCL). This open-label, phase II trial included patients (aged 6 years or older) with relapsed or refractory ALK-positive ALCL. Alectinib 300 mg was given orally twice a day (600 mg/d) for 16 cycles, and the duration of each cycle was 21 days. Patients who weighed less than 35 kg were given a reduced dose of alectinib of 150 mg twice a day (300 mg/d). Ten patients were enrolled, and the median age was 19.5 years (range, 6-70 years). Objective responses were documented in eight of 10 patients (80%; 90% confidence interval, 56.2-95.9), with six complete responses. The 1-year progression-free survival, event-free survival, and overall survival rates were 58.3%, 70.0%, and 70.0%, respectively. The median duration of therapy was 340 days. No unexpected adverse events occurred. The most common grade 3 and higher adverse event was a decrease in neutrophil count in two patients. Alectinib showed favorable clinical activity and was well tolerated in patients with ALK-positive ALCL who had progressed on standard chemotherapy. Based on the results of the current study, the Ministry of Health, Labour and Welfare of Japan approved alectinib for the treatment of recurrent or refractory ALK-positive ALCL in February 2020.

Antitumor activity and combined inhibitory effect of ceritinib with gemcitabine in pancreatic cancer.

Pancreatic cancer (PC) is predominantly incurable and is primarily treated with gemcitabine, but drug resistance commonly develops. Thus, new medicines are needed. Ceritinib (LDK378) is a second-generation tyrosine kinase inhibitor of anaplastic lymphoma kinase (ALK) with antitumor activity in various cancers. However, studies involving ceritinib for the treatment of PC are inadequate. We analyzed the combined effects of ceritinib and gemcitabine on PC and their mechanism of action. Three PC cell lines were used to evaluate the antitumor effects of ceritinib combined with gemcitabine. We analyzed cell viability using CCK-8 assays, determined apoptosis levels through flow cytometry, and analyzed autophagy and cell signaling pathways by Western blotting and tissue array analysis with samples from xenograft models. Ceritinib strongly inhibited the proliferation of PC cells in a dose-dependent manner, induced apoptosis, and inhibited autophagy and cell migration by regulating relevant factors. Ceritinib in combination with gemcitabine exhibited significant growth inhibition and additive antitumor effects in vitro. In vivo, gemcitabine and ceritinib reduced tumor size by up to 30%. In our study, ALK was shown to be highly expressed in various PC cells and tissues. Ceritinib strongly inhibited the levels of activated ALK in PC cells with subsequent effects on the downstream mediators STAT3, AKT, and ERK. In addition, ceritinib inhibited tumor progression in xenograft models. Overall, our research shows that ceritinib inhibits the ALK signaling pathway, leading to cell growth/angiogenesis inhibition in PC and the induction of apoptosis. We recommend using ceritinib as a new treatment for PC.NEW & NOTEWORTHY These data proved that ceritinib inhibits the anaplastic lymphoma kinase signaling pathway, leading to cell growth/angiogenesis inhibition and the induction of apoptosis by inhibiting STAT3, AKT, and ERK pathway in pancreatic cancer (PC). We recommend using ceritinib as a new treatment for PC.

Temozolomide treatment combined with AZD3463 shows synergistic effect in glioblastoma cells.

Temozolomide (TMZ) is used in the standard therapy regimen for patients with glioblastoma (GBM). However, some GBM patients do not respond to TMZ therapy. The combining therapeutic agents in GBM treatment are attracting considerable interest due to TMZ resistance. This study aims to identify the combinatorial effect of TMZ and AZD3463 on the viability of the T98G GBM cells. The cytotoxic effects of compounds were determined by using WST-8 assay. Flow cytometry was used to determine apoptosis and cell cycle profiles after treatments. Real-time PCR was used to identify mRNA expression of genes in the PI3K/AKT signaling pathway after treatments. IC50 concentrations of TMZ and AZD3463 were found to be 1.54 mM and 529 nM after incubation for 48 h, respectively. The combination treatment showed a synergistic effect on reducing the viability of GBM cells. Each one of TMZ, AZD3463, and combination treatments induced apoptosis. Treatments, either alone or the combination of these agents, caused the cell cycle arrest in distinct phases. TMZ and AZD3463 treatments, either alone or in combination, downregulated mRNA expression of genes in the PI3K/AKT signaling pathway. The combination of TMZ with AZD3463 may increase the efficacy of single TMZ treatment in GBM cells due to decreased expression of genes in the PI3K/AKT signaling pathway that is responsible for drug resistance and intratumoral heterogeneity.

KRCA-0008 suppresses ALK-positive anaplastic large-cell lymphoma growth.

Anaplastic lymphoma kinase (ALK), which belongs to the insulin receptor tyrosine kinase superfamily, plays an important role in nervous system development. Due to chromosomal translocations, point mutations, and gene amplification, constitutively activated ALK has been implicated in a variety of human cancers, including anaplastic large-cell lymphoma (ALCL), non-small cell lung cancer, and neuroblastoma. We evaluated the anti-cancer activity of the ALK inhibitor KRCA-0008 using ALCL cell lines that express NPM (nucleophosmin)-ALK. KRCA-0008 strongly suppressed the proliferation and survival of NPM-ALK-positive ALCL cells. Additionally, it induced G0/G1 cell cycle arrest and apoptosis by blocking downstream signals including STAT3, Akt, and ERK1/2. Tumor growth was strongly suppressed in mice inoculated with Karpas-299 tumor xenografts and orally treated with KRCA-0008 (50 mg/kg, BID) for 2 weeks. Our results suggest that KRCA-0008 will be useful in further investigations of ALK signaling, and may provide therapeutic opportunities for NPM-ALK-positive ALCL patients.

Pyrroformyl-containing 2,4-diaminopyrimidine derivatives as a new optimization strategy of ALK inhibitors combating mutations.

Aiming to identify new optimization strategy effective for ALK-mutations, two series of pyrroformyl-containing 2,4-diaminopyrimidine compounds (11a-o, 12a-o) were designed, synthesized and evaluated for their anti-proliferative activities against three cancer cell lines in vitro by MTT assay. The biological evaluations on cellular assay resulted in discovery of compound 11k, which performed considerable activity with IC50 value of 0.034 µM against H2228 cell. Meanwhile, 11k exhibited outstanding enzymatic inhibitory potency with IC50 values of 1.9 nM and 3.1 nM against ALKWT and ALKL1196M, respectively, surpassing the reference ceritinib (IC50 = 2.4 nM and 7.6 nM). Ultimately, the binding mode of 11k with ALK was established to explore the SARs. Overall, 11k was considered as a promising ALK inhibitor for mutation treatment.

Design, synthesis and biological evaluation of 2-arylaminopyrimidine derivatives bearing 1,3,8-triazaspiro[4,5]decan-4-one or piperidine-3-carboxamide moiety as novel Type-I1/2 ALK inhibitors.

Aiming to develop novel Type-I1/2 inhibitors of ALK to overcome extensive resistance mutations, especially the L1196M mutation surrounding the ATP pocket, two series of 2-arylaminopyrimidine derivatives (11a-f and 22a-t) were designed based on scaffold hopping. The extensive structural elaboration discovered compound 22o which possessed excellent IC50 values of 0.06 and 0.23 µM against ALK-positive Karpas299 and H2228 cell lines, respectively. Meanwhile, 22o displayed encouraging inhibitory potency in the ALKWT (2.5 nM) and ALKL1196M (6.5 nM) enzymatic assays. Furthermore, the AO/EB and Hoechst 33258 assays illustrated 22o could induce cell apoptosis in a dose-dependent manner. Eventually, the molecular docking of 22o with ALK clearly presented the vital interactions within the active site, which was in accordance with Type-I1/2 inhibitor binding mode.

Recent advances in targeted small-molecule inhibitor therapy for non-small-cell lung cancer-An update.

WHAT IS KNOWN AND OBJECTIVE: Targeted small molecule EGFR Tyrosine Kinase Inhibitors (TKI's) and the Anaplastic Lymphoma Kinase (ALK) inhibitors have been promising tools for advanced non-small-cell lung cancers (NSCLCs). However, tumours tend to develop subsequent mutations, rendering them drug-resistant. Hence, alternative pathways of therapy need to be explored. COMMENT: Gefitinib, erlotinib and afatinib, once considered as alternatives to platinum-based cytotoxic chemotherapy, have been rendered ineffective in patients with NSCLCs harbouring T790M mutation. Osimertinib is effective in T790M-mutant cancers, but not against those exhibiting the subsequent C797S mutation. ALK gene alterations have rendered tumours insensitive to crizotinib. However, lorlatinib and brigatinib are effective in tumours showing ALK+ mutations. Drugs acting through alternative pathways like the PD-1 pathway, BRAF, VEGFR, EGFR antibodies and NTRK inhibition have been showing promising results. WHAT IS NEW AND CONCLUSIONS: Osimertinib, brigatinib and allosteric C797S EGFR inhibitors like AI1045, BRAF inhibitors like LXH254 under trials and entrictinib, a recently approved NTRK inhibitor, have all shown improved progression-free survival compared with earlier generations of small molecule inhibitors for NSCLCs.

Carcinoma of Unknown Primary with EML4-ALK Fusion Response to ALK Inhibitors.

With the advent of next-generation sequencing (NGS) and precision medicine, investigators have determined that tumors from different tissue sources that have the same types of genetic mutations will have a positive response to the same targeted therapy. This finding has prompted us to seek potential therapeutic targets for patients with carcinoma of unknown primary (CUP) using NGS technology. Here, we reported a case of a woman with CUP resistance to chemotherapy. We detected 450 cancer-related gene alterations using three metastatic tumor specimens and found the presence of EML4 exon13 and ALK exon20 fusion. The tumor did respond to crizotinib, a first-generation ALK inhibitor. When her tumor progressed, circulating tumor DNA detection revealed ALK L1196 M and G1269A mutation resistance to crizotinib, but she had a response to brigatinib. This case revealed that NGS technology used to detect the genetic alterations in patients with CUP might be a reliable method to find potential therapeutic targets, although the primary lesion could not always be confirmed. KEY POINTS: This case exemplifies responsiveness to ALK inhibitor in carcinoma of unknown primary (CUP) with EML4-ALK fusion.Next-generation sequencing is an important diagnostic tool to find potential therapeutic targets in CUP.Liquid biopsy may be useful to provide critical information about resistance mechanisms in CUP to guide sequential treatment decision with targeted therapy.

Anaplastic lymphoma kinase expression in small-cell lung cancer.

AIMS: Anaplastic lymphoma kinase (ALK) immunohistochemistry has shifted from being a screening tool to being a sole determinant for ALK-targeted therapy. Recent articles have referred to small-cell lung cancer (SCLC) transformation as a resistance mechanism after ALK inhibitor treatments, but few reports have addressed ALK expression in treatment-naive SCLC in a comprehensive manner. Therefore, we examined ALK expression and the mechanisms in treatment-naive SCLCs. METHODS AND RESULTS: We examined ALK expression in a consecutive series of SCLC tumours, and the expression mechanism was analysed regarding gene rearrangement, copy number changes, and point mutations. We also examined whether SCLC with ALK expression can be suppressed by crizotinib treatment in vitro. Immunohistochemical results revealed that ALK was expressed in 16 of 142 (11.3%) SCLCs. The expression was focal and less intense, which is in contrast to strong and uniform expression in adenocarcinoma with ALK rearrangement. Two combined SCLCs showed a positive reaction restricted to the SCLC component. None of the known genetic alterations, including rearrangement, amplification, copy number gain, or point mutations, were associated with ALK expression. A SCLC cell line, SKLC2, which expressed ALK without known genetic alterations, was not inhibited by a practically achievable serum concentration of crizotinib. CONCLUSIONS: Anaplastic lymphoma kinase immunohistochemistry for treatment-naive SCLCs should not be used as a predictive biomarker for ALK inhibitor therapy, because the positive reactions were due to intrinsic expression of normal ALK transcript.

Meta-analysis comparing incidence of grade 3-4 neutropenia with ALK inhibitors and chemotherapy in patients with non-small-cell lung cancer.

Aim: This meta-analysis compared incidence of grade 3-4 neutropenia with ALK inhibitors versus chemotherapy in patients with non-small-cell lung cancer. Materials & methods: PubMed/MEDLINE was searched to identify Phase II and III randomized clinical trials published up to 25 October 2018. Summary incidence, relative risk and corresponding 95% CIs were calculated for grade 3-4 neutropenia. Results: Five randomized clinical trials were included. Relative risk (95% CI) of developing grade 3-4 neutropenia with ALK inhibitor versus chemotherapy was 0.27 (0.07-1.06). Probabilities of developing grade 3-4 neutropenia were 6.56 and 14.19%, respectively; no significant difference was found. Conclusion: In patients with non-small-cell lung cancer, incidence of grade 3-4 neutropenia with ALK-targeted therapy is not significantly different compared with chemotherapy.

Which Should Be Used First for ALK-Positive Non-Small-Cell Lung Cancer: Chemotherapy or Targeted Therapy? A Meta-Analysis of Five Randomized Trials.

Background and objectives: Targeted therapy is widely used in the era of precision medicine. Whether the sequence in which targeted therapy and chemotherapy are performed matters, is however not known. We examined the impact of the sequential treatment of targeted therapy and chemotherapy among advanced anaplastic lymphoma kinase (ALK), non-small cell lung cancer (NSCLC) patients. Materials and Methods: Randomized controlled trials comparing the use of ALK inhibitors with chemotherapy were included in this meta-analysis. We estimated the hazard ratios (HRs) and 95% confidence intervals (CI), for progression-free survival (PFS) and overall survival (OS) from a random effects model. Two-sided statistical tests were used to determine the significance of these estimates. Results: In five eligible studies (1404 patients), ALK targeted therapy, in comparison with chemotherapy, had a significantly higher PFS (HR = 0.48; 95% CI, 0.42⁻0.55), but not significantly higher OS (HR = 0.88; 95% CI, 0.72⁻1.07). Crossover from chemotherapy to ALK inhibitors was allowed after progression in all trials. The sensitivity analysis of the use of ALK inhibitors as either the first- or second-line treatment, showed improvements in PFS but not in OS. Conclusions: Our results indicate that using targeted therapy first improved PFS, but that the sequence in which the treatments were performed did not cause a significant difference in overall survival.

Alectinib.

Alectinib is an ATP-competitive small molecule and a second-generation inhibitor of ALK. EML4-ALK rearrangement is found in 3-5% of patients with NSCLC. The first-generation inhibitor crizotinib has changed the treatment dramatically, though most of the patients show disease progression within one year. Extra-thoracic progress, i.e., CNS metastases is common. The second-generation inhibitor alectinib has shown significant improvement in PFS and a remarkable prolongation of time to CNS progression. Alectinib has received approval as first-line therapy as well as second-line therapy after crizotinib failure. The toxicity profile is favorable compared to crizotinib and chemotherapy.

Design, synthesis and biological evaluation N2-(2-alkyoxy-6-aliphatic aminopyridin-3-yl)-2,4-diaminepyrimidine derivatives bearing acylamino or DBTD 'head' as potential ALK inhibitors.

Aiming to develop promising ALK inhibitors, two series of N2-(2-alkyoxy-6-aliphatic aminopyridin-3-yl)-2,4-diaminepyrimidine derivatives (22a-x and 23a-d) were designed according to scaffold hopping and bioisosterism principles. All compounds were efficiently synthesized by concise reactions and anti-proliferative activities on ALK-addicted H2228, Karpas299 cells and EGFR-expressive A549 cell were evaluated by MTT assay. Several compounds exhibited potential cytotoxic activities with IC50 values below 0.10 µM. Five compounds (22g, 22h, 22l, 22s and 23a) were selected for further enzymatic determination, resulting in the discovery of 22l against ALK and ALKL1196M with IC50 values of 2.1 nM and 3.8 nM. Particularly, western blot and cell apoptosis assays identified 22l as a promising ALK inhibitor, which was capable of obviously inhibiting cellular ALK activity and inducing cell apoptosis. Eventually, molecular docking modes of 22l with ALK confirmed structural basis in accordance with the SARs analysis.

Tracking a CAD-ALK gene rearrangement in urine and blood of a colorectal cancer patient treated with an ALK inhibitor.

BACKGROUND: Monitoring response and resistance to kinase inhibitors is essential to precision cancer medicine, and is usually investigated by molecular profiling of a tissue biopsy obtained at progression. However, tumor heterogeneity and tissue sampling bias limit the effectiveness of this strategy. In addition, tissue biopsies are not always feasible and are associated with risks due to the invasiveness of the procedure. To overcome these limitations, blood-based liquid biopsy analysis has proven effective to non-invasively follow tumor clonal evolution. PATIENTS AND METHODS: We exploited urine cell-free, trans-renal DNA (tr-DNA) and matched plasma circulating tumor DNA (ctDNA) to monitor a metastatic colorectal cancer patient carrying a CAD-ALK translocation during treatment with an ALK inhibitor. RESULTS: Using a custom next generation sequencing panel we identified the genomic CAD-ALK rearrangement and a TP53 mutation in plasma ctDNA. Sensitive assays were developed to detect both alterations in urine tr-DNA. The dynamics of the CAD-ALK rearrangement in plasma and urine were concordant and paralleled the patient's clinical course. Detection of the CAD-ALK gene fusion in urine tr-DNA anticipated radiological confirmation of disease progression. Analysis of plasma ctDNA identified ALK kinase mutations that emerged during treatment with the ALK inhibitor entrectinib. CONCLUSION: We find that urine-based genetic testing allows tracing of tumor-specific oncogenic rearrangements. This strategy could be effectively applied to non-invasively monitor tumor evolution during therapy. The same approach could be exploited to monitor minimal residual disease after surgery with curative intent in patients whose tumors carry gene fusions. The latter could be implemented without the need of patient hospitalization since urine tr-DNA can be self-collected, is stable over time and can be shipped at specified time-points to central labs for testing.

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.