The likelihood of being helped or harmed as a patient-centred tool to assess ALK-Inhibitors clinical impact and safety in ALK-addicted non-small cell lung cancer: A systematic review and sensitivity-analysis.

BACKGROUND: In untreated ALK-positive non-small cell lung cancer no randomized controlled trials (RCTs) are available directly comparing next-generation ALK-inhibitors. We conducted a sensitivity analysis using the likelihood of being helped or harmed (LHH). METHODS: Phase III trials comparing ALK-inhibitors to crizotinib were included. Efficacy outcomes were progression-free survival (PFS), objective response rate (ORR), PFS in patients with brain metastases and intracranial ORR. Safety outcomes were grade 3-4 adverse events (AEs), dose reductions and discontinuations. RESULTS: Six RCTs (1524 patients) were included. Lorlatinib and brigatinib had the lowest NNT for intracranial outcomes. Alectinib demonstrated favourable LHHs for grade 3-4 AEs, dose reductions and discontinuations. Brigatinib LHHs were low for common AEs, mainly laboratory anomalies and hypertension. Ensartinib showed mainly skin toxicity. Lorlatinib LHHs were low for specific grade 3-4 AEs, mainly metabolic alterations. CONCLUSIONS: The four ALK-inhibitors exhibited favourable risk-benefit ratios. Lorlatinib showed the lowest NNT for systemic efficacy and, alongside with Brigatinib, lower NNTs for intracranial efficacy. Alectinib exhibited higher LHHs for AEs. REGISTRATION: PROSPERO registration number: CRD42023389101.

Efficacy of ALK inhibitors in Asian patients with ALK inhibitor-naïve advanced ALK-positive non-small cell lung cancer: a systematic review and network meta-analysis.

Background: A previous network meta-analysis (NMA) compared the efficacy of anaplastic lymphoma kinase (ALK) inhibitors in ALK-positive non-small cell lung cancer (NSCLC). The phase III INSPIRE study of iruplinalkib was published recently. The present study aimed to add the results related to iruplinalkib to the NMA. Methods: A systematic literature search was performed in PubMed, Embase, Cochrane Library, Google, and Baidu. Randomized controlled trials (RCTs) reporting the independent review committee-assessed progression-free survival (PFS), objective response rate (ORR), or disease control rate (DCR) results of Asian patients with ALK inhibitor-naïve advanced ALK-positive NSCLC were eligible for inclusion in the NMA. Risk of bias was assessed using the Cochrane Risk of Bias 2 tool. Bayesian fixed-effect models were used for the direct and indirect pairwise comparisons. This study was registered with PROSPERO (CRD42024555299). Results: Eight studies, involving 1,477 Asian patients and seven treatments (crizotinib, alectinib, brigatinib, ensartinib, envonalkib, iruplinalkib, and lorlatinib), were included in the NMA. In terms of the overall risks of bias, all of the studies had "some concerns". All the next-generation ALK inhibitors were statistically superior to crizotinib in terms of PFS. Iruplinalkib had the best surface under the cumulative ranking curve (74.0%), followed by brigatinib (69.1%) and ensartinib (63.7%). Most of the pairwise comparisons did not reveal significant differences in the ORR and DCR. In terms of both the ORR and DCR, alectinib ranked first, followed by lorlatinib. Conclusions: Next-generation ALK inhibitors had better efficacy than crizotinib in the treatment of Asian patients with ALK inhibitor-naïve advanced ALK-positive NSCLC. Iruplinalkib may have more favorable PFS benefit than other ALK inhibitors for Asians.

A novel secondary ALK gene mutation which resistant to second-generation TKIs: a case report and literature review.

Background: Adenocarcinoma with positive echinoderm microtubule-associated protein-like 4 gene and anaplastic lymphoma kinase (EML4-ALK) gene fusion accounts for 3-7% of lung cancer cases and can be targeted with ALK tyrosine kinase inhibitors (TKIs). Second-generation TKIs are the standard of care for targeted populations, especially those with central nervous system (CNS) metastasis. However, most patients eventually experience disease progression because of drug resistance caused by multiple mechanisms, predominantly secondary mutations. Case description: We present a female advanced non-small cell lung cancer (NSCLC) case with positive EML4-ALK gene fusion, in which disease progression occurred in only 3 months after first-line treatment with alectinib. Two secondary mutations were detected by next-generation sequencing; one was V1180L located in exon 23, and the other was E803Q located in exon 14, which was a novel mutation that had never been reported. Ensartinib and ceritinib were administered as second-line and third-line treatments. However, the response to these TKIs was poor, and her overall survival was only 7 months. Conclusion: The secondary mutation E803Q located in exon 14 seems resistant to most second-generation ALK-TKIs. If there is an opportunity, the efficacy of the third-generation ALK-TKI loratinib should be tested.

Lorlatinib in the treatment of a rare pulmonary mucoepidermoid carcinoma with EML4-ALK fusion: a case report and literature review.

Pulmonary mucoepidermoid carcinoma (PMEC) is a rare tumor with limited clinical data available due to its low incidence. So far, there are no universal treatment guidelines for this malignant tumor. We present here the case of a 59-year-old female never smoker who was initially referred to our hospital with cough and hemoptysis and was eventually diagnosed with PMEC. Based on further genetic testing, echinoderm microtubule-associated protein-like4-anaplastic lymphoma kinase (EML4-ALK) fusion variants E20:A20 (V2) was found. The patient was treated with lorlatinib as the first-line treatment. This case is the first to describe the effectiveness of lorlatinib in treating an advanced high-grade PMEC with EML4-ALK fusion V2 mutation patient.

Diagnostic and Therapeutic Implications of a FUS::TFCP2 Fusion and ALK Activation in a Metastatic Rhabdomyosarcoma.

The identification of gene fusions in rare sarcoma subtypes can have diagnostic, prognostic, and therapeutic impacts for advanced cancer patients. Here, we present a case of a 31-year-old male with a lytic lesion of the left mandible initially diagnosed as an osteosarcoma but found to have a TFCP2 fusion and ALK alteration, redefining the diagnosis and providing rationale for a novel treatment strategy. Histologically, the tumor displayed hypercellular, spindled to epithelioid neoplasm and nuclear pleomorphism, while immunohistochemistry showed diffuse SATB2 and focal desmin staining. Whole genome and transcriptome analysis revealed a FUS::TFCP2 fusion, the defining alteration of a rare molecularly characterized subtype of soft tissue sarcoma termed intraosseous rhabdomyosarcoma. An internal ALK deletion and extremely high ALK RNA expression were also identified, suggesting potential benefit of an ALK inhibitor. This patient displayed a rapid and dramatic clinical and radiographic response to an ALK inhibitor, alectinib. Unfortunately, the response was short-lived, likely due to the advanced stage and aggressiveness of the disease. This report describes genome and transcriptome characterization of an intraosseous rhabdomyosarcoma, few of which exist in the literature, as well as providing evidence that inhibition of ALK may be a rational treatment strategy for patients with this exceedingly rare soft tissue sarcoma subtype characterized by TFCP2 fusions and ALK activation.

New findings on the incidence and management of CNS adverse reactions in ALK-positive NSCLC with lorlatinib treatment.

To explore the presentation and control of CNS adverse reactions in patients with ALK-positive NSCLC treated with lorlatinib. This study includes a retrospective case report from Sir Run Run Shaw Hospital on a lorlatinib-treated patient with CNS adverse reactions and a systematic literature review of similar cases until January 2023. The report detailed a case of a 74-year-old male with Grade III CNS adverse reactions 25 days after starting lorlatinib, which were reversible with dose modification and pharmacotherapy. The review indicated a 19.39% occurrence rate of such reactions, with a 17% improvement rate post-dose adjustment. CNS adverse reactions frequently occur in ALK-positive NSCLC patients on lorlatinib, yet they are reversible with appropriate management. Research should continue to optimize treatment protocols to decrease these reactions' frequency.

Incidentally Detected ALK-Positive Histiocytosis with EML4::ALK Fusion in a Solitary Pulmonary Nodule Following COVID-19 Infection: A Rare Case Report.

We hereby report a patient with ALK-positive histiocytosis with localized lung involvement. A 47-year-old woman presented with a solitary pulmonary nodule in the left upper lobe, 7 months after COVID infection. A well-defined 15 mm yellow mass was found in trisegmentectomy specimen. Histopathological examination revealed that the mass was composed of epithelioid and spindle cells with foamy cytoplasms. No necrosis, pleomorphism, or nuclear atypia was detected. The cells were positive for CD68, CD163, PU.1, ALK and negative for KRT, smooth muscle actin (SMA), S100, Melan-A, CD34, STAT6, and BRAF VE1. Flourescence in situ hybridization demonstrated ALK gene rearrangement, and next generation sequencing confirmed EML4::ALK fusion. Lung involvement in ALK-positive histiocytosis is characterized by the presence of pulmonary nodules, which can be seen in all forms of the disease. However, lung involvement is rarely seen in single-system ALK-positive histiocytosis. Our report represents the fourth documented instance of localized lung involvement in ALK-positive histiocytosis, an exceedingly rare occurrence, and it is the third instance with available molecular data.

Dissecting the clinicopathological, genomic, and prognostic significance of ALK rearrangement in resected lung adenocarcinoma.

OBJECTIVES: The ALINA trial introduced anaplastic lymphoma kinase (ALK) inhibitors in an early-stage context, generating notable interest. This study aims to investigate the characteristics and prognostic implications of ALK rearrangement in patients with resected lung adenocarcinoma (LUAD). METHODS: We retrospectively evaluated resected LUAD cases with documented ALK status from 2008 to 2020. The association between ALK positivity and clinicopathological characteristics, molecular profiles, and outcomes was explored. RESULTS: Among 4944 cases, 238 (4.8%) were ALK-positive, correlating with younger age and non-smokers. ALK positivity was also significantly associated with pure-solid nodules, spread through air spaces, and solid-predominant adenocarcinoma. ALK-positive tumors exhibited an overall low frequency of co-mutations (e.g., TP53, STK11). ALK positivity was associated with inferior recurrence-free survival (RFS) in stage I patients who did not receive adjuvant chemotherapy while with prolonged RFS in stage II and III patients who received adjuvant chemotherapy. Notably, six patients treated with adjuvant ALK inhibitors experienced no recurrence or metastasis during the follow-up period. Additionally, the administration of ALK inhibitors significantly improved post-recurrence survival in ALK-positive patients. CONCLUSIONS: ALK positivity was associated with specific aggressive pathological features and inferior RFS in stage I LUAD. ALK-positive patients seemed to benefit more from adjuvant chemotherapy. Active treatment with ALK inhibitors or chemotherapy should be considered for ALK-positive LUAD, although further evidence is warranted to expand their utility in early-stage disease management.

Identification and Treatment of Lung Cancer Oncogenic Drivers in a Diverse Safety Net Setting.

INTRODUCTION: Advances in the testing and treatment of patients with non-small cell lung cancer (NSCLC) harboring oncogenic drivers have improved outcomes. Little is known about testing and treatment patterns in diverse patient populations. METHODS: We conducted a retrospective study in a diverse cohort of patients treated in the John Peter Smith safety net healthcare system. We determined patterns of blood- and tissue-based testing and treatment of patients with EGFR and ALK alterations. Cox proportional-hazards regression models were used to assess the impact of EGFR and ALK testing. RESULTS: A total of 220 patients were included, 97 (44%) were non-Hispanic White, 72 (33%) were Black, 28 (13%) were Hispanic, and 23 (10%) were Asian. EGFR and ALK testing increased over time from 55% and 52%, respectively, in 2017 to 87% and 82%, respectively, in 2021. Frequency of EGFR alterations were highest in Asian patients (45%) and comparable among other groups (6-13%). Frequency of ALK alterations were highest in Hispanic (13%), and Asian (11%) patients, and were 2% for both Black and non-Hispanic White patients. In a multivariate model, lack of testing was associated with worse survival (aHR 1.6; P = .003) and testing positive for EGFR (aHR 0.43; P = .01) or ALK (aHR 0.28; P = .04) was associated with improved survival. Race and ethnicity were not associated with survival differences. CONCLUSION: As molecular testing for oncogenic mutations in NSCLC increases, druggable alterations such as ALK and EGFR can be identified in all race-ethnicity groups and are associated with improved outcomes.

Comparative Efficacy and Safety of Lorlatinib Versus Alectinib and Lorlatinib Versus Brigatinib for ALK-Positive Advanced/Metastatic NSCLC: Matching-Adjusted Indirect Comparisons.

INTRODUCTION: The comparative efficacy and safety of lorlatinib, a third-generation anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitor (TKI), versus second-generation ALK TKIs as a first-line treatment for ALK+ advanced/metastatic nonsmall cell lung cancer (NSCLC) remains uncertain as there are no head-to-head clinical trials. METHODS: Matching-adjusted indirect comparisons (MAICs) were conducted using phase III trial data demonstrating superior efficacy over crizotinib, a first-generation ALK TKI. MAICs were conducted to compare lorlatinib (CROWN) versus alectinib (ALEX and ALESIA) and brigatinib (ALTA-1L) with matching based on prespecified effect modifiers. Efficacy outcomes included progression-free survival (PFS), objective response (OR), and time to progression in the central nervous system (TTP-CNS). Safety outcomes included Grade ≥3 adverse events (AEs) and AEs leading to treatment discontinuation, dose reduction, or dose interruption. RESULTS: Lorlatinib was estimated to improve PFS compared to alectinib (ALEX) (HR: 0.54 [95% CI: 0.33, 0.88]) and brigatinib (ALTA-1L) (HR: 0.51 [95% CI: 0.31, 0.82]). Lorlatinib was estimated to improve TTP-CNS compared with brigatinib (HR: 0.19 [95% CI: 0.05, 0.71]). The estimated Grade ≥3 AE rate was higher with lorlatinib than with alectinib (RR: 1.48 [95% CI: 1.13, 1.94]); however, no differences were observed in other safety endpoints (ie, AEs leading to discontinuation, dose reduction, or interruption) or compared to brigatinib. CONCLUSION: Lorlatinib was estimated to have superior efficacy over first- and second-generation ALK-TKIs, but a higher rate of Grade ≥3 AEs compared to alectinib. These data support the use of lorlatinib as a first-line treatment for ALK+ advanced/metastatic NSCLC.

ALKTERNATE: A Pilot Study Alternating Lorlatinib With Crizotinib in ALK-Positive NSCLC With Prior ALK Inhibitor Resistance.

Introduction: ALK-positive lung cancers represent a molecularly diverse disease. With drug exposure, driving selection pressure, and resistance pathways, disease relapse will emerge. There is compelling rationale to investigate novel treatment strategies, informed by dynamic circulating tumor DNA (ctDNA) monitoring. Methods: The single-arm, pilot study ALKTERNATE investigated fixed alternating cycles of lorlatinib intercalated with crizotinib in individuals resistant to second-generation ALK inhibitors. Dynamic ctDNA explored the correlation with disease response and disease recurrence and defined disease resistance. The primary outcome was time-to-treatment failure, a composite of tolerability, feasibility, and efficacy. Secondary outcomes included standard survival measures, toxicity, pharmacokinetic analysis, and patient-reported outcomes. Tertiary outcomes were proteogenomic analyses of tissue and plasma. Results: A total of 15 individuals were enrolled; three encountered primary resistance to lorlatinib induction. There were 12 participants who received alternating therapy, and this approach revealed safety, feasibility, and effectiveness. Patient-reported outcomes were maintained or improved on therapy, and toxicity was consistent with previous reports. The pharmacokinetic measures were similar to the single-arm drug experience. Median time-to-treatment failure was 10 months; overall survival was 23 months. ctDNA profiles indicated inferior survival in those with preexistent TP53 mutations and those without clear or cleared ctDNA at trial induction. The study defined a vastly heterogeneous population with an abundance of ALK coexisting with non-ALK resistance variants. Conclusions: ALKTERNATE revealed feasibility with a novel alternating ALK inhibitor strategy in ALK-positive NSCLC. Results support progressing inquiry into this approach and propose a flexible design with drug(s) selected and alternating time frames, informed by real-time plasma profiling. Moving this concept to treatment naive may also optimize impact.

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.

A novel molecular target, superoxide dismutase 1, in ALK inhibitor-resistant lung cancer cells, detected through proteomic analysis.

BACKGROUNDS: To the best of our knowledge, there are no reports of proteomic analysis for the identification of unknown proteins involved in resistance to anaplastic lymphoma kinase (ALK) inhibitors. In this study, we investigated the proteins involved in resistance to alectinib, a representative ALK inhibitor, through proteomic analysis and the possibility of overcoming resistance. METHODS: An ALK-positive lung adenocarcinoma cell line (ABC-11) and the corresponding alectinib-resistant cell line (ABC-11/CHR2) were used. Two-dimensional difference gel electrophoresis (2D DIGE) was performed; the stained gel was scanned and the spots were analyzed using DeCyder TM2D 7.0. Mass spectrometry (MS) with the UltrafleXtreme matrix-assisted laser desorption ionization-tandem time-of-flight (MALDI-TOF/TOF) MS system was performed. For the MS/MS analysis, the samples were spotted on an AnchorChipTM 600 TF plate. The peptide masses obtained in the reflector positive mode were acquired at m/z of 400-6,000. MS/MS data were searched against the NCBI protein databases. Growth inhibition was measured using an MTT assay. The isobologram and combination index were calculated based on the median-effect analysis. Western blotting was performed using antibodies, including superoxide dismutase (SOD) 1, MET, ERK, PARP, AKT, and BRCA1. RESULTS: The 2D DIGE for ABC-11 and ABC-11/CHR2 showed different expression levels in about 2,000 spots. SOD was identified from spots highly expressed in resistant strains. Western blotting also confirmed SOD1 overexpression in ABC-11/CHR2. siSOD1 enhanced the growth inhibitory effects of alectinib, increased cleaved PARP levels, and decreased pERK, pAKT, and BRCA1 levels with a combination of alectinib. In addition, the combination of LCS-1, an SOD1 inhibitor, and alectinib synergistically suppressed the growth in ABC-11/CHR2, but not in ABC-11. CONCLUSIONS: SOD1 overexpression is thought to be a mechanism for alectinib resistance, suggesting the possibility of overcoming resistance using SOD1 inhibitors.

Alectinib Versus Crizotinib in Asian Patients With Treatment-Naïve Advanced ALK-Positive NSCLC: Five-Year Update From the Phase 3 ALESIA Study.

Introduction: Previous results from the phase 3 ALESIA study (NCT02838420) revealed that alectinib (a central nervous system [CNS]-active, ALK inhibitor) had clinical benefits in treatment-naïve Asian patients with advanced ALK-positive NSCLC, consistent with the global ALEX study. We present updated data after more than or equal to 5 years of follow-up from the "last patient in" date. Methods: Adult patients with treatment-naïve, advanced ALK-positive NSCLC from mainland China, South Korea, and Thailand were randomized 2:1 to receive twice-daily 600 mg alectinib (n = 125) or 250 mg crizotinib (n = 62). The primary endpoint was investigator-assessed progression-free survival. Secondary or exploratory endpoints included overall survival, objective response rate, time to CNS progression, and safety. Results: At the data cutoff (May 16, 2022), the median survival follow-up was 61 and 51 months in the alectinib and crizotinib arms, respectively. Median progression-free survival was 41.6 months with alectinib versus 11.1 months with crizotinib (stratified hazard ratio = 0.33, 95% confidence interval: 0.23-0.49). Overall survival data remain immature; 5-year overall survival rates were 66.4% (alectinib arm) versus 56.1% (crizotinib arm). Objective response rate was 91.2% versus 77.4% with alectinib and crizotinib, respectively. CNS progression was delayed with alectinib versus crizotinib (cause-specific hazard ratio = 0.16, 95% confidence interval: 0.08-0.32). Median treatment duration was longer with alectinib versus crizotinib (42.3 versus 12.6 mo). No new safety signals were observed. Conclusions: With four additional years of follow-up, these updated results confirm the clinical benefit and manageable safety of alectinib in Asian patients with advanced ALK-positive NSCLC, and confirm alectinib as a standard-of-care treatment for patients with advanced ALK-positive NSCLC.

Bilateral breast metastases from anaplastic lymphoma kinase-positive lung cancer in a male: a case report.

BACKGROUND: Distant metastases from lung cancer are commonly found in the brain, bone, and liver. Metastases to the breast from non-mammary malignancies are extremely rare, and their clinical presentations remain unclear. CASE PRESENTATION: We herein report a case of bilateral breast metastases from anaplastic lymphoma kinase-positive advanced lung cancer in a 51-year-old Japanese male patient. During the course of systemic treatment for advanced lung cancer, computed tomography revealed bilateral breast enlargement without contrast enhancement, a finding consistent with gynecomastia. While other metastatic lesions responded to chemotherapy, both breast masses grew vertically like nodules. The breast masses were immunohistochemically diagnosed as metastases from lung cancer and were removed surgically. Simultaneous bilateral breast metastases from malignancies of other organs, like ones in this case, have rarely been described. CONCLUSIONS: It is important to keep in mind that breast metastases from nonmammary malignancies are a possible explanation for unusual breast findings in a patient with a history of malignancies.

Redefining Recovery: The Transformative Impact of the ALINA Trial on Adjuvant Therapy for ALK-Positive Non-Small Cell Lung Cancer.

On April 18, 2024, the Food and Drug Administration approved alectinib as an adjuvant treatment for patients with anaplastic lymphoma kinase (ALK)-positive non-small cell lung cancer (NSCLC) after tumor resection. This approval was grounded in the outcomes of the ALINA trial, which demonstrated that alectinib significantly enhances disease-free survival compared to traditional platinum-based chemotherapy in the adjuvant setting. The ALINA trial is notable not just for advancing ALK tyrosine kinase inhibitors (TKIs) into the adjuvant setting but also for its innovative approach of comparing them to adjuvant chemotherapy, distinguishing it from other landmark trials.

ALK-positive histiocytosis: Report of a rare case with exclusive involvement of the central nervous system in an adult woman.

ALK-positive histiocytosis is a rare histiocytic disease characterized by ALK positivity. It was first described in 2008 as a systemic disease in infants. The disease often shows positivity for CD68 and CD163 on immunohistochemistry, and genomic analysis frequently reveals KIF5B::ALK fusions. ALK-positive histiocytosis typically follows an indolent course and has a promising prognosis, with conventional treatments usually being effective. Here, we report a rare case of ALK-positive histiocytosis with exclusive involvement of the central nervous system in a 33-year-old Asian adult woman. Although cranial MRI suggested a meningioma, immunohistochemical workup showed that the ALK-positive tumor cells expressed macrophage/histiocyte markers such as CD163 and CD68. Additionally, second-generation sequencing revealed a KIF5B::ALK fusion. Our case highlights the importance of the differential diagnosis in adult central nervous system tumors, emphasizing the combination of morphology, immunophenotype, and molecular approach with ALK status evaluation to confirm a diagnosis of ALK-positive histiocytosis. This case also expands the clinicopathologic spectrum of ALK-positive histiocytosis.

Real-world treatment sequencing and effectiveness of second- and third-generation ALK tyrosine kinase inhibitors for ALK-positive advanced non-small cell lung cancer.

INTRODUCTION: With multiple targeted therapies approved for anaplastic lymphoma kinase (ALK)-positive metastatic non-small cell lung cancer (NSCLC), it is increasingly important to understand outcomes with various sequences of next-generation ALK tyrosine kinase inhibitors (TKIs). We describe contemporary sequencing patterns and treatment effectiveness of first-line (1L) and second-line (2L) treatments in patients who received second-generation ALK TKIs in the 1L treatment of ALK-positive NSCLC in the United States. METHODS: A cohort of adults with ALK-positive advanced NSCLC who initiated treatment with 1L alectinib or brigatinib between June 2017 and April 2021 in the Flatiron Health electronic health record-derived de-identified database were followed through April 2023. Time to treatment discontinuation (TTD) in 1L and 2L, TTD on 1L plus 2L sequential therapy (TTD2), and total time on sequential ALK TKI therapy (including beyond 2L) were evaluated. RESULTS: Patients (N=273) were followed up for a median duration of 28.9 months. Among patients who discontinued 1L therapy, 22% died after 1L discontinuation (median time from discontinuation to death, 4.0 months) without receiving 2L therapy. Median (95% confidence interval [CI]) TTD was 21.9 (15.2-25.8) and 7.3 (5.3-10.2) months in 1L and 2L, respectively. Median (95% CI) TTD2 was 29.4 (25.1-36.1) months and total time on sequential ALK TKI treatment was 28.0 (23.6-32.9) months. CONCLUSIONS: In this large real-world study, TTD2 and the total time on sequential ALK TKIs was approximately 2.5 years. The high attrition rate from 1L to 2L and the longest clinical benefit observed with 1L therapy support using the drug with the longest 1L effectiveness up front in patients with ALK-positive advanced NSCLC.