Dossier — ALK

The FDA prescribing information directs selection of metastatic NSCLC patients for crizotinib based on ALK positivity in tumor specimens detected by an FDA-approved test. This establishes ALK rearrangement/positivity as the clinically actionable biomarker for ALK inhibition.

In the randomized phase 3 PROFILE 1014 trial, patients were centrally confirmed to have an ALK rearrangement using the Vysis ALK Break-Apart FISH assay. Crizotinib improved median progression-free survival to 10.9 versus 7.0 months (HR 0.45) and objective response rate was 74% versus 45% with chemotherapy.

In the phase 2 lorlatinib biomarker analysis of 198 previously treated ALK-positive NSCLC patients, those who had failed at least one second-generation ALK TKI had higher objective response rates when an ALK mutation was detected: 62% versus 32% by plasma genotyping and 69% versus 27% by tissue genotyping.…

Analysis of 103 repeat biopsies from ALK-positive patients progressing on ALK inhibitors identified distinct secondary ALK resistance mutations, including enrichment of G1202R after second-generation therapy; resistant models without ALK mutations were also resistant to lorlatinib, consistent with non-ALK-dependent…

In 22 ALK-positive NSCLC patients with acquired resistance to ALK TKIs, plasma and tissue ALK mutation calls were 100% concordant in contemporaneous paired samples. ALK mutations emerged and disappeared according to the administered TKI, and the common second-generation-TKI resistance mutation ALK G1202R was…

In a discordant NSCLC series, three clearly ALK-IHC-negative/FISH-positive samples were negative for ALK fusion transcripts by two RNA-based assays; four patients with borderline FISH results received ALK TKIs without benefit. This weakens the assumption that genomic break-apart signals alone demonstrate target…

In PROFILE 1014, 343 previously untreated patients with advanced ALK-positive NSCLC were randomized to crizotinib or platinum-pemetrexed chemotherapy. Crizotinib significantly improved progression-free survival, objective response rate, lung-cancer symptoms, and quality of life, establishing ALK-directed therapy as a…

In the randomized phase 3 ALEX trial, alectinib reduced the risk of progression or death versus crizotinib (HR 0.47; 95% CI 0.34–0.65) and reduced CNS progression (cause-specific HR 0.16). Twelve-month progression-free survival was 68.4% with alectinib versus 48.7% with crizotinib.

In ALTA-1L, brigatinib reduced the risk of disease progression or death versus crizotinib (HR 0.49; P<0.001); 12-month progression-free survival was 67% with brigatinib versus 43% with crizotinib. The treatment effect was particularly pronounced in patients with baseline brain metastases (HR 0.20).

The 7-year CROWN update reported a progression-free survival hazard ratio of 0.19 for lorlatinib versus crizotinib; median progression-free survival remained unreached with lorlatinib, and the study demonstrated durable benefit through extended follow-up, including in patients with baseline brain metastases.

The FDA approved ensartinib on December 18, 2024, based on the randomized phase 3 eXALT3 trial. Among 290 patients, ensartinib significantly improved independently reviewed progression-free survival versus crizotinib (HR 0.56; 95% CI 0.40–0.79; P=0.0007), with median progression-free survival of 25.8 versus 12.7…

With 84.2% of chemotherapy-arm patients crossing over to crizotinib, the unadjusted overall-survival hazard ratio was 0.760 (95% CI 0.548–1.053; P=0.0978); median OS was not reached with crizotinib versus 47.5 months with chemotherapy. The OS advantage appeared only after a crossover-adjusted analysis.

The ASCO living guideline recommends alectinib, brigatinib, or lorlatinib as first-line therapy and notes that pivotal trials used crizotinib as the comparator; it explicitly acknowledges the absence of head-to-head trials between second-generation ALK TKIs and lorlatinib. This makes differentiation primarily…

In the phase III CROWN trial, five-year PFS was 60% with lorlatinib versus 8% with crizotinib, with a PFS hazard ratio of 0.19. Median time to intracranial progression was not reached with lorlatinib versus 16.4 months with crizotinib, with an intracranial-progression hazard ratio of 0.06. The publication describes…

The FDA approved ensartinib on December 18, 2024, for previously untreated ALK-positive locally advanced or metastatic NSCLC. In the randomized eXALT3 trial, ensartinib improved PFS versus crizotinib with HR 0.56; median PFS was 25.8 versus 12.7 months. Overall survival was not statistically different, and the FDA…

A systematic molecular study of post-treatment samples and engineered models found that lorlatinib was the only tested ALK inhibitor to potently inhibit ALK phosphorylation across all evaluated single secondary ALK mutations, including G1202R. This supports a differentiated role for lorlatinib after progression on…

The ASCO 2026.3.0 living guideline identifies ongoing development of next-generation or fourth-generation ALK inhibitors, including NVL-655 and TPX-0131, with activity against compound ALK mutations that commonly emerge after lorlatinib. This indicates that current differentiation is dynamic and that lorlatinib’s…

In the phase 3 ALTA-3 trial, median blinded independent review committee-assessed PFS was 19.3 months with brigatinib versus 19.2 months with alectinib (HR 0.97; p=0.8672), and the study met its futility criterion. Treatment-related laboratory abnormalities were common with both drugs, although their safety profiles…

EML4-ALK fusions are causal drivers with unambiguous direction of effect in fusion-positive NSCLC.

The original study identified a small chromosome 2p inversion producing EML4–ALK in NSCLC cells; the fusion transcript was detected in 5 of 75 patients (6.7%), was distinct from EGFR-mutant tumors, and transformed fibroblasts in culture and nude mice.

The TCGA study profiled 230 untreated lung adenocarcinomas using matched tumor/normal DNA, RNA, copy-number, methylation and proteomic data; ALK fusions were identified among the recurrent kinase rearrangements, with 3 of 230 tumors reported as ALK-fusion positive in the genomic analysis.

GeneReviews defines ALK-related inherited susceptibility as risk for neuroblastoma, ganglioneuroblastoma, and ganglioneuroma. It describes somatic ALK translocations in NSCLC separately and does not identify NSCLC as a phenotype of germline ALK susceptibility.

In a US real-world cohort of 19,895 advanced NSCLC patients with documented ALK testing, 519 (2.6%) had an ALK rearrangement; prevalence was 8.9% in never-smokers, 21.6% in patients aged 18–39 years, and 6.3% among Asian patients.

Comprehensive genomic profiling of 39,159 NSCLC cases identified ALK internal inversions as the sole ALK rearrangement in 6 cases (0.02%) and internal deletions in 3 cases (0.01%). RNA testing confirmed EML4–ALK in 2 of 2 evaluated inversion cases, and all 3 treated inversion cases had durable responses to ALK…

In 1,026 NSCLC patients tested with a 58-gene hereditary-cancer panel, plausible genetic susceptibility was identified in 4.7% (14 pathogenic and 34 likely pathogenic cases). The study emphasized that the genetic predisposition of lung cancer remains incompletely elucidated; the reported susceptibility findings…

The fusion drives constitutive kinase activity; the mechanism is precisely defined.

The FDA-approved XALKORI prescribing information states that ALK translocations produce oncogenic fusion proteins, and that these fusions activate and dysregulate ALK expression and signaling, contributing to increased proliferation and survival. It also reports concentration-dependent inhibition of ALK…

The original Nature study identified EML4-ALK in human NSCLC and demonstrated that the fusion gene transforms cells, establishing a direct mechanistic link between ALK rearrangement and lung-cancer pathogenesis.

In EML4-ALK lung-cancer models, inhibition of MAPK signaling suppressed growth comparably to ALK inhibition, whereas PI3K-AKT or JAK-STAT inhibition had less effect. EML4-ALK activated all three major RAS isoforms through the EML4 HELP domain, and genetic activation of RAS, RAF, or MEK rescued cells from ALK…

The study found that EML4-ALK variant 1 forms cytoplasmic condensates through phase separation in human cancer cells and in genetically engineered mouse-model tumors. Mutating aromatic residues in EML4 impaired condensate formation, reduced downstream signaling—especially STAT3 phosphorylation—and decreased malignant…

In the original EML4-ALK study, a selective ALK inhibitor strongly inhibited only 1 of 3 EML4-ALK-positive NSCLC cell lines; the other two were resistant and showed no growth arrest or apoptosis. The authors noted that ALK inhibition alone might not be sufficient for some EML4-ALK tumors.

Different EML4-ALK variants and fusion partners showed differential sensitivity to structurally distinct ALK inhibitors, correlated with differences in fusion-protein stability. This complicates treating “ALK” as a uniform mechanistic biomarker.

In H3122 and H2228 EML4-ALK-positive lung adenocarcinoma cells, siRNA knockdown of ALK reduced cell viability by at least 60% and significantly reduced colony formation; these effects were not observed in ALK-rearrangement-negative HCC827 and H157 cells. ALK knockdown also reduced viability in the patient-derived…

In an ALK-positive patient-derived NSCLC cell line, genome-wide CRISPR/Cas9 knockout screening under alectinib or lorlatinib identified MIG6/ERRFI1 loss as a resistance mechanism. MIG6 knockout was validated in vitro and in vivo and restored survival under ALK-TKI treatment through EGFR–MAPK and PI3K/AKT/mTOR…

A CRISPR-Cas9 gene-deletion screen performed under ALK inhibition identified KEAP1 loss as a modifier of response. KEAP1 loss reduced treatment-associated oxidative stress and enabled proliferation despite MAPK-pathway inhibition, providing perturbational evidence for a genetically defined resistance route to…

Genome-scale CRISPR-Cas9 drug-resistance screens found that KEAP1 loss modulated response to ALK inhibitors; validation included KEAP1 knockout in MGH-065 ALK-mutant cells treated with LDK378 or crizotinib, and H3122 cells treated with crizotinib. This indicates that ALK inhibition can be bypassed by a redox/metabolic…

In a patient-derived ALK-rearranged NSCLC line, loss of MIG6/ERRFI1 conferred tolerance or resistance to ALK inhibitors; low-dose EGF further enhanced survival and proliferation, while EGFR blockade resensitized MIG6-deficient cells. This weakens the premise that perturbing ALK alone is sufficient across relevant…

Somatic genome editing generated EML4-ALK V1- and V3-driven lung tumors, and multiplexed CRISPR inactivation of 29 tumor-suppressor genes produced variant-specific effects on tumorigenesis. V3 was more oncogenic than V1, and pharmacogenomic analyses indicated that tumor genotype can alter response to ALK inhibition,…

Narrow adult expression predicts a favourable on-target safety profile.

In a primary NSCLC study, the selective ALK inhibitor TAE684 inhibited growth of EML4-ALK-positive H3122 cells in vitro and in vivo, inhibited AKT phosphorylation, and induced apoptosis; activity was not uniform across all EML4-ALK-positive lines, indicating context-dependent but strong ALK dependency.

In the first expanded clinical study of crizotinib, 82 patients with advanced ALK-positive NSCLC were treated; the reported objective response rate was approximately 57%, demonstrating substantial antitumor dependence on ALK kinase activity in molecularly selected tumors.

A targeted kinase-domain ALK knockout mouse model produced viable and fertile homozygous animals without gross embryonic or adult morphological abnormalities, but with reduced testosterone, delayed pubertal onset, and altered gonadotropin-releasing-hormone neuron numbers. This supports a therapeutic window while…

The FDA-aligned XALKORI prescribing information reports common adult NSCLC adverse reactions including visual disorders, gastrointestinal toxicity, edema, elevated transaminases, fatigue, dizziness, and neuropathy, and identifies serious organ-specific warnings requiring monitoring or treatment interruption.

The June 2026 FDA label reports hepatotoxicity in 41% of the pooled 533-patient safety population, grade ≥3 hepatotoxicity in 8%, ILD/pneumonitis in 1.3%, renal impairment in 12% including fatal cases, bradycardia in 11%, elevated CPK in 56%, and hemolytic anemia in 3.1% of ALINA patients. The label also warns of…

In the phase 3 CROWN trial, grade 3–4 adverse events occurred in 72% of lorlatinib-treated patients versus 56% with crizotinib, driven mainly by altered lipid levels. Lorlatinib-specific frequent events included hypercholesterolemia in 70%, hypertriglyceridemia in 64%, cognitive effects in 21%, mood effects in 16%,…

The original discovery study identified the EML4–ALK fusion in NSCLC cells and detected the fusion transcript in 5 of 75 NSCLC patients (6.7%); forced expression transformed cells, supporting a tumor-cell-intrinsic role.

In a multicenter tissue-microarray study of 594 resected NSCLCs, ALK rearrangement was identified in 7 cases by FISH, and all seven ALK-positive cases were identified by ALK immunohistochemistry. The ALK-positive tumors included acinar, papillary, minimally invasive and pleomorphic lung carcinomas.

A conditional transgenic mouse model expressed EML4–ALK under the surfactant protein C promoter, targeting lung alveolar epithelial cells, and developed EML4–ALK-positive lung tumors. This is mechanistic preclinical evidence and does not by itself establish the exact human cell of origin.

In a 1,426-specimen FISH study, the proportion of rearranged cells varied substantially; only 8.1% of specimens had more than 50% ALK-positive cells, while 8.5% had 10–15% positive cells. The authors also observed atypical patterns and noted that not every cell in an ALK-positive tumor necessarily showed a detectable…

In 54 extensively sampled ALK-rearranged lung carcinomas, all tumors had at least a focal adenocarcinoma component, but 3 also showed squamous differentiation and 2 showed sarcomatoid differentiation. Although characteristic patterns were enriched, no histologic parameter was completely sensitive or specific for ALK…

Studies of ALK-rearranged lung adenocarcinoma report association with solid, micropapillary and papillary-predominant patterns and signet-ring tumor cells; ALK-positive tumors commonly show TTF-1 expression, supporting localization to pulmonary adenocarcinoma cells rather than a nonspecific stromal compartment.

Several approved ALK TKIs demonstrate strong small-molecule tractability.

The FDA label identifies lorlatinib as a kinase inhibitor for metastatic ALK-positive NSCLC, selected by an FDA-approved test, with oral tablet dosing at 100 mg once daily. This provides direct regulatory evidence for both target tractability and a validated modality.

In the randomized phase 3 CROWN trial, first-line lorlatinib significantly prolonged progression-free survival versus crizotinib and produced higher intracranial response activity in previously untreated advanced ALK-positive NSCLC. The study enrolled 296 patients and established a CNS-active, third-generation oral…

In the randomized phase 3 ALEX trial, alectinib improved progression-free survival versus crizotinib and markedly reduced CNS progression: 12-month progression-free survival was 68.4% versus 48.7%, and CNS progression occurred in 12% versus 45% of patients, respectively.

The FDA approved adjuvant alectinib for ALK-positive NSCLC after tumor resection based on the global randomized ALINA trial in resectable stage IB to IIIA disease. ALK rearrangements were identified using FDA-approved testing or the VENTANA ALK D5F3 CDx assay, demonstrating clinical and diagnostic tractability in…

The FDA-authorized companion-diagnostic list includes ALK rearrangement testing for multiple approved ALK-directed therapies, including alectinib, crizotinib, and ceritinib, using assays such as FoundationOne CDx; FDA-authorized ALK FISH and IHC assays are also listed for selecting patients for ALK-directed treatment.

A peer-reviewed study combining mutagenesis experiments with repeat biopsies from lorlatinib-resistant patients found compound ALK resistance mutations in 7 of 20 clinical samples (35%). The findings show that sequential first-, second-, and third-generation ALK inhibitors can select compound mutations that confer…