Novel therapeutic strategies for rare mutations in non-small cell lung cancer.

Lung cancer is still the leading cause of cancer-related mortality. Over the past two decades, the management of non-small cell lung cancer (NSCLC) has undergone a significant revolution. Since the first identification of activating mutations in the epidermal growth factor receptor (EGFR) gene in 2004, several genetic aberrations, such as anaplastic lymphoma kinase rearrangements (ALK), neurotrophic tropomyosin receptor kinase (NTRK) and hepatocyte growth factor receptor (MET), have been found. With the development of gene sequencing technology, the development of targeted drugs for rare mutations, such as multikinase inhibitors, has provided new strategies for treating lung cancer patients with rare mutations. Patients who harbor this type of oncologic driver might acquire a greater survival benefit from the use of targeted therapy than from the use of chemotherapy and immunotherapy. To date, more new agents and regimens can achieve satisfactory results in patients with NSCLC. In this review, we focus on recent advances and highlight the new approval of molecular targeted therapy for NSCLC patients with rare oncologic drivers.

Focal adhesion kinase-YAP signaling axis drives drug-tolerant persister cells and residual disease in lung cancer.

Targeted therapy is effective in many tumor types including lung cancer, the leading cause of cancer mortality. Paradigm defining examples are targeted therapies directed against non-small cell lung cancer (NSCLC) subtypes with oncogenic alterations in EGFR, ALK and KRAS. The success of targeted therapy is limited by drug-tolerant persister cells (DTPs) which withstand and adapt to treatment and comprise the residual disease state that is typical during treatment with clinical targeted therapies. Here, we integrate studies in patient-derived and immunocompetent lung cancer models and clinical specimens obtained from patients on targeted therapy to uncover a focal adhesion kinase (FAK)-YAP signaling axis that promotes residual disease during oncogenic EGFR-, ALK-, and KRAS-targeted therapies. FAK-YAP signaling inhibition combined with the primary targeted therapy suppressed residual drug-tolerant cells and enhanced tumor responses. This study unveils a FAK-YAP signaling module that promotes residual disease in lung cancer and mechanism-based therapeutic strategies to improve tumor response.

Targeting NRAS via miR-1304-5p or farnesyltransferase inhibition confers sensitivity to ALK inhibitors in ALK-mutant neuroblastoma.

Targeting Anaplastic lymphoma kinase (ALK) is a promising therapeutic strategy for aberrant ALK-expressing malignancies including neuroblastoma, but resistance to ALK tyrosine kinase inhibitors (ALK TKI) is a distinct possibility necessitating drug combination therapeutic approaches. Using high-throughput, genome-wide CRISPR-Cas9 knockout screens, we identify miR-1304-5p loss as a desensitizer to ALK TKIs in aberrant ALK-expressing neuroblastoma; inhibition of miR-1304-5p decreases, while mimics of this miRNA increase the sensitivity of neuroblastoma cells to ALK TKIs. We show that miR-1304-5p targets NRAS, decreasing cell viability via induction of apoptosis. It follows that the farnesyltransferase inhibitor (FTI) lonafarnib in addition to ALK TKIs act synergistically in neuroblastoma, inducing apoptosis in vitro. In particular, on combined treatment of neuroblastoma patient derived xenografts with an FTI and an ALK TKI complete regression of tumour growth is observed although tumours rapidly regrow on cessation of therapy. Overall, our data suggests that combined use of ALK TKIs and FTIs, constitutes a therapeutic approach to treat high risk neuroblastoma although prolonged therapy is likely required to prevent relapse.

A pragmatic guide for management of adverse events associated with lorlatinib.

Lorlatinib is a brain-penetrant, third-generation tyrosine kinase inhibitor (TKI) indicated for the treatment of anaplastic lymphoma kinase (ALK)-positive metastatic non-small cell lung cancer (NSCLC). In clinical trials, lorlatinib has shown durable efficacy and a manageable safety profile in treatment-naive patients and in those who have experienced progression while receiving first- and/or second-generation ALK TKIs. Lorlatinib has a distinct safety profile from other ALK TKIs, including hyperlipidemia and central nervous system effects. Clinical trial data showed that most adverse events (AEs) can be managed effectively or reversed with dose modifications (such as dose interruptions or reductions) or with concomitant medications without compromising clinical efficacy or quality of life for patients. A pragmatic approach to managing AEs related to lorlatinib is required. We present patient-focused recommendations for the evaluation and management of select AEs associated with lorlatinib developed by clinicians and nurses with extensive lorlatinib expertise in routine clinical practice. The recommendations follow the general framework of "prepare, monitor, manage, reassess" to streamline AE management and assist in practical, actionable, and personalized patient care.

Concurrent inhibition of ALK and SRC kinases disrupts the ALK lung tumor cell proteome.

Precision oncology has revolutionized the treatment of ALK-positive lung cancer with targeted therapies. However, an unmet clinical need still to address is the treatment of refractory tumors that contain drug-induced resistant mutations in the driver oncogene or exhibit resistance through the activation of diverse mechanisms. In this study, we established mouse tumor-derived cell models representing the two most prevalent EML4-ALK variants in human lung adenocarcinomas and characterized their proteomic profiles to gain insights into the underlying resistance mechanisms. We showed that Eml4-Alk variant 3 confers a worse response to ALK inhibitors, suggesting its role in promoting resistance to targeted therapy. In addition, proteomic analysis of brigatinib-treated cells revealed the upregulation of SRC kinase, a protein frequently activated in cancer. Co-targeting of ALK and SRC showed remarkable inhibitory effects in both ALK-driven murine and ALK-patient-derived lung tumor cells. This combination induced cell death through a multifaceted mechanism characterized by profound perturbation of the (phospho)proteomic landscape and a synergistic suppressive effect on the mTOR pathway. Our study demonstrates that the simultaneous inhibition of ALK and SRC can potentially overcome resistance mechanisms and enhance clinical outcomes in ALK-positive lung cancer patients. ONE SENTENCE SUMMARY: Co-targeting ALK and SRC enhances ALK inhibitor response in lung cancer by affecting the proteomic profile, offering hope for overcoming resistance and improving clinical outcomes.

Prediction of pharmacokinetics of an anaplastic lymphoma kinase inhibitor in rat and monkey: application of physiologically based pharmacokinetic model as an alternative tool to minimise animal studies.

The pharmacokinetic (PK) and toxicokinetic profile of a drug from its preclinical evaluation helps the researcher determine whether the drug should be tested in humans based on its safety and toxicity.Preclinical studies require time and resources and are prone to error. Moreover, according to the United States Food and Drug Administration Modernisation Act 2, animal testing is no longer mandatory for new drug development, and an animal-free alternative, such as cell-based assay and computer models, can be used.Different physiologically based PK models were developed for an anaplastic lymphoma kinase inhibitor in rats and monkeys after intravenous and oral administration using its physicochemical properties and in vitro characterisation data.The developed model was validated against the in vivo data available in the literature, and the validation results were found within the acceptable limit. A parameter sensitivity analysis was performed to identify the properties of the compound influencing the PK profile.This work demonstrates the application of the physiologically based PK model to predict the PKs of a drug, which will eventually assist in reducing the number of animal studies and save time and cost of drug discovery and development.

Clinical outcomes of ALK+ non-small cell lung cancer in Denmark.

BACKGROUND: Real-world clinical outcomes of anaplastic lymphoma kinase positive (ALK+) non-small cell lung cancer (NSCLC) patients vary. This study aimed to investigate the treatment and clinical outcomes of all ALK+ NSCLC patients in Denmark in the period 2011-2018, regardless of disease stage. MATERIALS AND METHODS: A national pathology database with complete coverage was used to identify ALK+ NSCLC patients diagnosed between 2011 and 2018. Clinical data were obtained through retrospective chart reviews. Overall survival (OS) and duration of treatment (DOT) were analyzed using Kaplan-Meier methodologies. RESULTS: A total of 209 ALK+ NSCLC patients were included. The cohort had a slight overrepresentation of female patients (56.5%) with a mean age of 61.6 years. Most patients were adenocarcinoma cases (97%) and presented with an ECOG performance status of 0-1 (79%). Stage IIIb-IVb patients comprised 70% of the cohort. The use of ALK-tyrosine kinase inhibitors (TKIs) as first-line treatment increased over time, with the 1st generation ALK-TKI crizotinib being the predominant treatment in the 1st line. In 1st line treatment, 2nd generation ALK-TKIs had a median DOT more than twice the median DOT of crizotinib (25.1 and 9.1 months, respectively). The median OS for the entire cohort was 44.0 months. Patients with stage I-IIIA disease had a median OS that had not been reached, while those with stage IIIb-IVb disease had a median OS of 31.8 months. Patients with stage IIIb-IVb disease receiving an ALK-TKI as 1st line treatment had a median OS of 42.5 months with immature follow-up. Brain metastases at diagnosis or choice of 1st line treatment did not statistically significantly impact OS. CONCLUSION: This study gives insights into the treatment and outcome of ALK+ NSCLC patients in Denmark and provides a real-world confirmation of the superior disease control provided by 2nd generation ALK-TKIs as compared to the 1st generation ALK-TKI crizotinib.

Lorlatinib Effectiveness and Quality-of-Life in Patients with ALK-Positive NSCLC Who Had Failed Second-Generation ALK Inhibitors: Canadian Real-World Experience.

Lorlatinib is the only targeted therapy approved in Canada to treat patients with anaplastic lymphoma kinase (ALK)-positive non-small cell lung cancer (NSCLC) whose tumor has progressed despite treatment with second-generation ALK tyrosine kinase inhibitor (TKI), a patient population with high unmet need and lack of publicly reimbursed targeted treatments in Canada. We prospectively examined the real-world effectiveness and impact of lorlatinib on quality-of-life in 59 lorlatinib-treated patients, characterized as: median age of 62.0 years; 47.5% were female; 32.2% had central nervous system metastases; 50.8% had 2+ prior ALK TKI lines; and alectinib was the most common ALK TKI (72.9%) administered before lorlatinib, including 44.1% who received first-line alectinib. With a median follow-up of 15.3 months (IQR: 6.2-19.2), median time-to-treatment discontinuation of lorlatinib was 15.3 months (95% CI: 7.9-not reached), with 54.2% (95% CI: 40.8-65.9%) of patients without treatment discontinuation at 12 months. At baseline, the mean health utility score (HUS) was 0.744 (SD: 0.200). At 3 months, patients receiving lorlatinib demonstrated a 0.069 (95% CI: 0.020-0.118; p = 0.007) average HUS increase over baseline; HUS was maintained at 6 and 12 months. Thus, patients with ALK-positive NSCLC post second-generation ALK TKI remained on lorlatinib for a meaningful duration of time while their quality-of-life was preserved.

Risks of cardiovascular toxicities associated with ALK tyrosine kinase inhibitors in patients with non-small-cell lung cancer: a meta-analysis of randomized control trials.

BACKGROUND: Anaplastic lymphoma kinases (ALK) tyrosine kinase inhibitors (TKIs) are effective and safe targeted therapies used in advanced ALK-positive non-small cell lung cancers (NSCLC). However, ALK-TKIs associated cardiovascular toxicities in patients with ALK-positive NSCLCremain incompletely characterized. We conducted the first meta-analysis to investigate this. RESEARCH DESIGN AND METHODS: To determine the cardiovascular toxicities associated with these agents, we carried out a meta-analysis comparing ALK-TKIs with chemotherapy and a meta-analysis comparing crizotinib with other ALK-TKIs. Statistical analysis was conducted to calculate the RRs and 95% confidence intervals (CIs) by using either random effects or fixed-effect models according to the heterogeneity of the included studies. RESULTS: A total of 11 studies (2855 patients) were included. ALK-TKIs ranked to have more severe cardiovascular toxicities than chemotherapy (RR 5.03, 95% CI 1.97-12.84, P = 0.0007) . Compared with other ALK-TKIs, increased risks of cardiac disorders and VTEs associated with crizotinib were found (cardiac disorders RR 1.75, 95% CI 1.07-2.86, P = 0.03; risk of VTEs RR 3.97, 95% CI 1.69-9.31, P = 0.002; respectively). CONCLUSION: ALK-TKIs were associated with higher risks of cardiovascular toxicities. Special attention should be given to the risks of cardiac disorders and VTEs related to crizotinib therapy.

Autocrine EGF and TGF-α promote primary and acquired resistance to ALK/c-Met kinase inhibitors in non-small-cell lung cancer.

Drug resistance severely limits the clinical therapeutic value of molecularly targeted drugs. Growth factors gain a tremendous amount of focus due to the ability to promote drug resistance in non-small-cell lung cancer (NSCLC). However, whether tumor cells themselves can mediate drug resistance by secreting growth factors needs further clarification. Here, we first screened growth factors to identify autocrine epidermal growth factor (EGF) and transforming growth factor alpha (TGF-α) that caused primary resistance to the ALK inhibitor TAE684 in H3122 cells and the c-MET-specific inhibitor SGX-523 in EBC-1 cells. Next, we discovered increased autocrine production of EGF and TGF-α in established acquired resistant H3122/TR and EBC-1/SR cells. Importantly, overexpression of EGF and TGF-α in two NSCLC cell lines produced resistance to TAE684 and SGX-523. Clinically, NSCLC patients with high expression of EGF and TGF-α developed primary resistance to crizotinib. Mechanistically, autocrine EGF and TGF-α activated EGFR signaling pathways to survive targeted c-Met and ALK inhibition. Furthermore, combined treatment with gefitinib circumvented EGF- and TGF-α-mediated primary and acquired resistance to TAE684/SGX-523. Taken together, these results suggested increased autocrine EGF and TGF-α conferred primary and acquired resistance to ALK/c-Met kinase inhibitors in NSCLC.

Use of ALK-tyrosine kinase inhibitors (ALK TKI) in clinical practice, overall survival, and treatment duration - a Swedish nationwide retrospective study.

BACKGROUND: The real-world treatment and outcomes of patients with anaplastic lymphoma kinase positive (ALK+) advanced non-small cell lung cancer treated with ALK Tyrosine Kinase Inhibitor (TKI) drugs in Sweden is not well described. MATERIAL AND METHODS: A retrospective population-based cohort study was conducted using Swedish national registers. All patients with a filled prescription for an ALK TKI between January 2012 and October 2020 were included. The sequencing of ALK TKI and duration of treatment (DOT) were described, and overall survival (OS) was estimated using the Kaplan-Meier method. Patients were stratified based on treatment with frontline chemotherapy, presence of CNS metastases prior to the first ALK TKI, and generation of ALK TKI agent. RESULTS: Among the total of 579 patients, 549 (95%) underwent a therapy sequence in line with current clinical practice with 204 (37%) patients receiving frontline chemotherapy. Single-line ALK TKI was given to 366 patients (crizotinib: 211; alectinib: 146; ceritinib: 9), whereas 128 patients received two different ALK TKI (frontline crizotinib: 100, alectinib: 24, ceritinib: 4); 40 patients received three lines and 15 patients four ALK TKI lines or more. With frontline chemotherapy, the mean (standard deviation) DOT was 1.07 (1.25) years for the entire TKI therapy sequence compared to 1.23 (1.28) years with frontline ALK TKI. The median (95% confidence interval) OS was 1.83 (1.48-2.13) years for the entire cohort, 1.44 (0.89-1.98) years for patients given frontline chemotherapy, and 2.02 (1.60-2.58) years for patients given frontline ALK TKI. CONCLUSION: This study provides a unique overview of the patient population treated with ALK TKI in Sweden and reveals the treatment patterns applied in real clinical practice. More research is needed when longer follow-up data are available for later-generation ALK TKI, to fully understand ALK TKI sequencing and its effect on patient survival in a real-world setting.

Response to treatment with an ALK-TKI in a patient with advanced lung adenocarcinoma with concurrent ALK fusion and high PD-L1 expression: A case report.

RATIONALE: Previous studies have shown that PD-L1 TPS ≥50% in lung cancer rarely overlaps with driver oncogenes such as epidermal growth factor receptor and anaplastic lymphoma kinase (ALK). The initial gene detection of the patient in this study showed ALK fusion combined with high expression of PD-L1. We explored the treatment options for this patient. PATIENT CONCERNS: A 34-year-old woman presented for the first time with "repeated fever and cough for 20 days." The patient denied any underlying medical history. DIAGNOSIS: After a series of imaging examinations and needle biopsy, the patient was diagnosed as stage IV lung adenocarcinoma with multiple liver and bone metastases (EML4-ALK fusion, PD-L1 TPS 80%). INTERVENTIONS: The patient was initially given alectinib targeted therapy. After progression, a second round of genetic testing was performed and the patient was detected to have both ALK fusion and BRAF mutation. The patient was then successively changed to treatment with ensatinib combined with dabrafenib, and lorlatinib combined with dabrafenib. OUTCOMES: The initial efficacy evaluation of alectinib was PR, but its PFS was only 4 months. The patient only achieved an overall survival of 10 months. LESSONS: Non-small cell lung cancer with an ALK fusion and high PD-L1 expression responds poorly to most current treatment options, with survival time after ALK-tyrosine kinase inhibitor treatment notably shorter than that of patients with an ALK fusion alone.

Alectinib for the treatment of pretreated RET-rearranged advanced NSCLC: Results of the ETOP ALERT-lung trial.

BACKGROUND: Alectinib, a highly selective next generation ALK-inhibitor, has exhibited potent anti-tumour activity in RET-rearranged NSCLC in the preclinical stage. METHODS: ALERT-lung is a single-arm, phase II trial evaluating the activity of alectinib for the treatment of pretreated RET-rearranged advanced NSCLC. Alectinib was administered orally, 600 mg, twice per day until progression, refusal or unacceptable toxicity (treatment could continue beyond progression, if patient was deriving clinical benefit). Patient recruitment closed prematurely due to discouraging results for alectinib in a phase I/II study in the same indication. RESULTS: All 14 patients who enrolled until the premature accrual closure, received at lease one dose of alectinib. Among them, median age was 61 years, majority (71 %) was female, never smokers, of ECOG PS 1. No objective response (complete or partial response) was recorded. Of the 13 evaluable patients, three (23 %) achieved and maintained disease stabilisation for 24 weeks. Up to 31 March 2021 (median follow-up 15.9 months), 12 PFS-events (92 %) were observed, with median PFS of 3.7 months (95 % C.I.: 1.8 - 7.3 months). Overall, three deaths (23 %) were reported. Seven patients (50 %) experienced grade ≥ 3 adverse events, while three discontinued treatment due to erythema multiforme of grade 3, related to alectinib. No treatment-related serious adverse event was reported. CONCLUSIONS: Accrual into our trial was terminated early in response to other reports of limited activity of alectinib in patients with RET-fusion NSCLC and the emergence of more potent selective RET-inhibitors. Also in our trial, alectinib did not show the expected potential for anti-tumour activity in NSCLC.

Anaplastic lymphoma kinase tyrosine kinase inhibitors associated gastrointestinal obstruction, perforation, and ulceration: an analysis of the FDA adverse event reporting system database (FAERS).

BACKGROUND : There have been cases reporting anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitors (TKIs) and associated serious gastrointestinal (GI) adverse drug reactions (gastrointestinal obstruction, perforation, and ulceration). These adverse drug reactions are not in the drug package inserts, and the drug relationships are not proven in the literature.  AIM: We aimed to examine the potential association between GI obstruction, perforation, and ulceration, and ALK-TKIs by data mining of the US FDA Adverse Event Reporting System (FAERS). METHOD  : We conducted a disproportionality analysis of GI obstruction, perforation, and ulceration by estimating the reporting odds ratios (ROR) and the information component (IC) with 95% confidence intervals. RESULTS : A total of 279 cases of ALK-TKI-associated GI obstruction, perforation, and ulceration from January 1, 2011, to December 31, 2020, were identified. GI obstruction, perforation, and ulceration cause 16% of cases of death. A significantly increased reporting rate for GI obstruction [ROR 1.77 (1.45-2.15); IC 0.82 (0.53-2.03)] and perforation [ROR 1.61 (1.28-2.02); IC 0.68 (0.35-1.92)] was observed for ALK-TKIs as a drug class. The signal of GI ulceration was detected only in crizotinib [ROR 1.23 (1.01-1.50); IC 0.29 (0.01-1.51)]. A statistically significant ROR and IC emerged for the site of the esophagus.  CONCLUSION : Overall, the pharmacovigilance study of the FAERS indicates slightly increased reporting of GI obstruction and perforation, which may cause severe or even fatal outcomes among ALK-TKIs users.

A systematic review of economic evaluations of tyrosine kinase inhibitors for non-small cell lung cancer (NSCLC).

INTRODUCTION: Although tyrosine kinase inhibitors (TKIs) have improved the efficacy of treatment for non-small cell lung cancer (NSCLC), the accessibility of TKIs is limited due to high costs. Despite the critical role of the cost-effectiveness of TKIs on decision-making, no systematic reviews have compared the cost-effectiveness of comparable TKIs. Therefore, we systemically reviewed the economic evaluation studies on various TKIs for NSCLC. AREAS COVERED: We searched PubMed and the Cochran Library to identify the published economic evaluation studies of TKIs in NSCLC patients that were published by January 2022. All of the included studies (n = 38) evaluated the cost-effectiveness of epidermal growth factor receptor (EGFR)-TKIs (n = 29) or anaplastic lymphocyte kinase (ALK)-TKIs (n = 9). The cost-effectiveness results were reported as the incremental cost-effectiveness ratio per quality-adjusted life-year, except for three studies. EXPERT OPINION: We found that the economic evaluation studies of the first and second generation of EGFR-TKIs and ALK-TKIs varied by the country and study settings, such as comparator and input parameters. In 12 studies, osimertinib (EGFR-TKI) was not cost-effective compared to other first/second EGFR-TKIs, regardless of the study settings. More evidence can be provided about cost-effectiveness of the third-generation TKIs in future research.

Third-generation EGFR and ALK inhibitors: mechanisms of resistance and management.

The discoveries of EGFR mutations and ALK rearrangements as actionable oncogenic drivers in non-small-cell lung cancer (NSCLC) has propelled a biomarker-directed treatment paradigm for patients with advanced-stage disease. Numerous EGFR and ALK tyrosine kinase inhibitors (TKIs) with demonstrated efficacy in patients with EGFR-mutant and ALK-rearranged NSCLCs have been developed, culminating in the availability of the highly effective third-generation TKIs osimertinib and lorlatinib, respectively. Despite their marked efficacy, resistance to these agents remains an unsolved fundamental challenge. Both 'on-target' mechanisms (largely mediated by acquired resistance mutations in the kinase domains of EGFR or ALK) and 'off-target' mechanisms of resistance (mediated by non-target kinase alterations such as bypass signalling activation or phenotypic transformation) have been identified in patients with disease progression on osimertinib or lorlatinib. A growing understanding of the biology and spectrum of these mechanisms of resistance has already begun to inform the development of more effective therapeutic strategies. In this Review, we discuss the development of third-generation EGFR and ALK inhibitors, predominant mechanisms of resistance, and approaches to tackling resistance in the clinic, ranging from novel fourth-generation TKIs to combination regimens and other investigational therapies.

Long-term effects of pharmacological inhibition of anaplastic lymphoma kinase in neurofibromatosis 1 mutant mice.

Neurofibromatosis type 1 (NF1) is associated with behavioral alterations and cognitive impairments. There is a genetic interaction between NF1 and the receptor tyrosine kinase Alk. Short-term pharmacological Alk inhibition, with a compound FDA-approved for cancer starting 10 days prior to cognitive testing, was shown to improve cognitive performance of NF1 heterozygous (HET) mice. However, effects of long-term Alk inhibition on behavioral cognitive performance are not known. Therefore, in the study described below we determine the effects of prolonged pharmacological Alk inhibition for 24 weeks on behavioral and cognitive performance of NF1 HET mice. As these studies have the ultimate objective of developing a treatment for humans with neurofibromatosis and acceptable side effects in the context of cancer are not acceptable in the context of long-term treatment of patients with neurofibromatosis, we included additional behavioral tests of anxiety-like and depressive-like behaviors as well. Long-term effects of Alk inhibition had genotype-dependent effects, consistent with a specific interaction between Alk and NF1. Beneficial effects of long-term Alk inhibition in NF1 HET mice included rescue of impairments in object recognition in NF1 HET males and females, and improved cognitive performance of NF1 HET males and females in the water maze test. In contrast, long-term Alk inhibition had detrimental effects in WT mice not seen after short-term treatments. As longer treatments are translationally more relevant for NF1 patients, these data highlight the important to assess long-term effects of drugs, especially of repurposed drugs used originally as part of cancer therapy.

ALK-positive histiocytosis: a new clinicopathologic spectrum highlighting neurologic involvement and responses to ALK inhibition.

ALK-positive histiocytosis is a rare subtype of histiocytic neoplasm first described in 2008 in 3 infants with multisystemic disease involving the liver and hematopoietic system. This entity has subsequently been documented in case reports and series to occupy a wider clinicopathologic spectrum with recurrent KIF5B-ALK fusions. The full clinicopathologic and molecular spectra of ALK-positive histiocytosis remain, however, poorly characterized. Here, we describe the largest study of ALK-positive histiocytosis to date, with detailed clinicopathologic data of 39 cases, including 37 cases with confirmed ALK rearrangements. The clinical spectrum comprised distinct clinical phenotypic groups: infants with multisystemic disease with liver and hematopoietic involvement, as originally described (Group 1A: 6/39), other patients with multisystemic disease (Group 1B: 10/39), and patients with single-system disease (Group 2: 23/39). Nineteen patients of the entire cohort (49%) had neurologic involvement (7 and 12 from Groups 1B and 2, respectively). Histology included classic xanthogranuloma features in almost one-third of cases, whereas the majority displayed a more densely cellular, monomorphic appearance without lipidized histiocytes but sometimes more spindled or epithelioid morphology. Neoplastic histiocytes were positive for macrophage markers and often conferred strong expression of phosphorylated extracellular signal-regulated kinase, confirming MAPK pathway activation. KIF5B-ALK fusions were detected in 27 patients, whereas CLTC-ALK, TPM3-ALK, TFG-ALK, EML4-ALK, and DCTN1-ALK fusions were identified in single cases. Robust and durable responses were observed in 11/11 patients treated with ALK inhibition, 10 with neurologic involvement. This study presents the existing clinicopathologic and molecular landscape of ALK-positive histiocytosis and provides guidance for the clinical management of this emerging histiocytic entity.

Evaluation of the absolute oral bioavailability of the anaplastic lymphoma kinase/c-ROS oncogene 1 kinase inhibitor lorlatinib in healthy participants.

PURPOSE: Lorlatinib is a third-generation tyrosine kinase inhibitor currently approved for the treatment of anaplastic lymphoma kinase (ALK)-positive metastatic non-small cell lung cancer. This open-label, phase 1, randomized two-sequence, two-treatment, two-period, crossover study investigated the absolute oral bioavailability of lorlatinib in healthy participants. METHODS: Eligible participants were randomized to receive two treatments in one of two sequences: lorlatinib 100 mg single oral dose followed by lorlatinib 50 mg intravenous (IV) dose, or lorlatinib IV dose followed by lorlatinib oral dose, each with at least a 10-day washout between successive lorlatinib doses. Blood samples for pharmacokinetics were collected for up to 144 hours (h) after dosing. Validated liquid chromatographic-tandem mass spectrometry was used to determine plasma concentrations of lorlatinib and its benzoic acid metabolite PF-06895751. RESULTS: In total, 11 participants were enrolled (mean age 37.6 years, all male). The adjusted geometric mean (90% confidence interval) for the absolute oral bioavailability was 80.78% (75.73-86.16%). Using non-compartmental analysis, the estimated arithmetic mean elimination plasma half-life of lorlatinib was 25.5 and 27.0 h after the oral and IV doses, respectively. No deaths, serious adverse events (AEs), or severe AEs were reported, and most treatment-emergent AEs were mild in severity, with two events of transaminase increase of moderate severity. All treatment-emergent AEs were resolved by the end of the study. CONCLUSION: Both oral and IV lorlatinib were well-tolerated in healthy participants and oral lorlatinib is highly bioavailable after oral administration.