Further demonstration of the diversity of chromosomal changes involving 2p23 in ALK-positive lymphoma: 2 cases expressing ALK kinase fused to CLTCL (clathrin chain polypeptide-like)

Acquired resistance to crizotinib in novel CDK14-ALK and CLTC-ALK fusions of ALK-positive large B-cell lymphoma identified by next-generation sequencing

Anaplastic lymphoma kinase-positive large B-cell lymphoma (ALK+ LBCL) is a rare subtype of non-Hodgkin lymphoma. ALK inhibitors are being tried to treat recurrent/refractory ALK+ LBCL. A majority of patients with ALK+ tumors respond to crizotinib, but partial cases ultimately develop resistance about a year later. Here, we report a case of ALK+ LBCL carrying a new fusion gene involving CDK14 and ALK, CLTC-ALK gene rearrangements and MTOR gene mutation. The patient had progressive disease after combination of crizotinib and chemotherapy treatment about 5.5 months later, accompanied by reduced abundance of CDK14-ALK, increased abundance of CLTC-ALK and a novel MFHAS1 gene mutation. However, MTOR mutation turned negative. The patient received alectinib combined with hyper-CVAD, then followed by alectinib as monotherapy for 21 months. The patient achieved partial response and remained in a stable condition. This case suggests that CDK14-ALK fusion gene may be more sensitive to crizotinib than CLTC-ALK fusion gene. MTOR is associated with the anti-tumor mechanism of ALK inhibitors. MFHAS1 gene mutation and/or CLTC-ALK gene copy number amplification may involve resistance to crizotinib. Furthermore, alectinib may inhibit the carcinogenicity of these gene changes and improve the prognosis of ALK+ LBCL.

ALK fusions in the pan-cancer setting: another tumor-agnostic target?

Anaplastic lymphoma kinase (ALK) alterations (activating mutations, amplifications, and fusions/rearrangements) occur in ~3.3% of cancers. ALK fusions/rearrangements are discerned in >50% of inflammatory myofibroblastic tumors (IMTs) and anaplastic large cell lymphomas (ALCLs), but only in ~0.2% of other cancers outside of non-small cell lung cancer (NSCLC), a rate that may be below the viability threshold of even large-scale treatment trials. Five ALK inhibitors -alectinib, brigatinib, ceritinb, crizotinib, and lorlatinib-are FDA approved for ALK-aberrant NSCLCs, and crizotinib is also approved for ALK-aberrant IMTs and ALCL, including in children. Herein, we review the pharmacologic tractability of ALK alterations, focusing beyond NSCLC. Importantly, the hallmark of approved indications is the presence of ALK fusions/rearrangements, and response rates of ~50-85%. Moreover, there are numerous reports of ALK inhibitor activity in multiple solid and hematologic tumors (e.g., histiocytosis, leiomyosarcoma, lymphoma, myeloma, and colorectal, neuroendocrine, ovarian, pancreatic, renal, and thyroid cancer) bearing ALK fusions/rearrangements. Many reports used crizotinib or alectinib, but each of the approved ALK inhibitors have shown activity. ALK inhibitor activity is also seen in neuroblastoma, which bear ALK mutations (rather than fusions/rearrangements), but response rates are lower (~10-20%). Current data suggests that ALK inhibitors have tissue-agnostic activity in neoplasms bearing ALK fusions/rearrangements.

Decoding Oncofusions: Unveiling Mechanisms, Clinical Impact, and Prospects for Personalized Cancer Therapies

Cancer-associated gene fusions, also known as oncofusions, have emerged as influential drivers of oncogenesis across a diverse range of cancer types. These genetic events occur via chromosomal translocations, deletions, and inversions, leading to the fusion of previously separate genes. Due to the drastic nature of these mutations, they often result in profound alterations of cellular behavior. The identification of oncofusions has revolutionized cancer research, with advancements in sequencing technologies facilitating the discovery of novel fusion events at an accelerated pace. Oncofusions exert their effects through the manipulation of critical cellular signaling pathways that regulate processes such as proliferation, differentiation, and survival. Extensive investigations have been conducted to understand the roles of oncofusions in solid tumors, leukemias, and lymphomas. Large-scale initiatives, including the Cancer Genome Atlas, have played a pivotal role in unraveling the landscape of oncofusions by characterizing a vast number of cancer samples across different tumor types. While validating the functional relevance of oncofusions remains a challenge, even non-driver mutations can hold significance in cancer treatment. Oncofusions have demonstrated potential value in the context of immunotherapy through the production of neoantigens. Their clinical importance has been observed in both treatment and diagnostic settings, with specific fusion events serving as therapeutic targets or diagnostic markers. However, despite the progress made, there is still considerable untapped potential within the field of oncofusions. Further research and validation efforts are necessary to understand their effects on a functional basis and to exploit the new targeted treatment avenues offered by oncofusions. Through further functional and clinical studies, oncofusions will enable the advancement of precision medicine and the drive towards more effective and specific treatments for cancer patients.

How molecular advances may improve the diagnosis and management of PTCL patients

Peripheral T-cell lymphomas (PTCL) comprised more than 30 rare heterogeneous entities, representing 10 to 15% of adult non-Hodgkin lymphomas. Although their diagnosis is still mainly based on clinical, pathological, and phenotypic features, molecular studies have allowed for a better understanding of the oncogenic mechanisms involved and the refinement of many PTCL entities in the recently updated classifications. The prognosis remains poor for most entities (5-year overall survival < 30%), with current conventional therapies based on anthracyclin-based polychemotherapy regimen, despite many years of clinical trials. The recent use of new targeted therapies appears to be promising for relapsed/refractory patients, such as demethylating agents in T-follicular helper (TFH) PTCL. However further studies are needed to evaluate the proper combination of these drugs in the setting of front-line therapy. In this review, we will summarize the oncogenic events for the main PTCL entities and report the molecular targets that have led to the development of new therapies. We will also discuss the development of innovative high throughput technologies that aid the routine workflow for the histopathological diagnosis and management of PTCL patients.

ALK-positive lung cancer: a moving target

Anaplastic lymphoma kinase (ALK) is a potent oncogenic driver in lung cancer. ALK tyrosine kinase inhibitors yield significant benefit in patients with ALK fusion-positive (ALK+) lung cancers; yet the durability of response is limited by drug resistance. Elucidation of on-target resistance mechanisms has facilitated the development of next-generation ALK inhibitors, but overcoming ALK-independent resistance mechanisms remains a challenge. In this Review, we discuss the molecular underpinnings of acquired resistance to ALK-directed therapy and highlight new treatment approaches aimed at inducing long-term remission in ALK+ disease.

Hallmarks of Anaplastic Lymphoma Kinase Inhibitors with Its Quick Emergence of Drug Resistance

Anaplastic lymphoma kinase (ALK) is one of the most popular targets for anticancer therapies. In the past decade, the use of anaplastic lymphoma tyrosine kinase inhibitors (ALK-TKIs), including crizotinib and ceritinib, has been a reliable and standard options for patients with lung cancer, particularly for patients with nonsmall cell lung carcinoma. ALK-targeted therapies initially benefit the patients, yet, resistance eventually occurs. Therefore, resistance mechanisms of ALK-TKIs and the solutions have become a formidable challenge in the development of ALK inhibitors. In this review, based on the knowledge of reported ALK inhibitors, we illustrated the crystal structures of ALK, summarized the resistance mechanisms of ALK-targeted drugs, and proposed potential therapeutic strategies to prevent or overcome the resistance.

ALK fusion promotes metabolic reprogramming of cancer cells by transcriptionally upregulating PFKFB3

Anaplastic lymphoma kinase (ALK), a receptor tyrosine kinase of the insulin receptor kinase subfamily, is activated in multiple cancer types through translocation or overexpression. Although several generations of ALK tyrosine kinase inhibitors (TKIs) have been developed for clinic use, drug resistance remains a major challenge. In this study, by quantitative proteomic approach, we identified the glycolytic regulatory enzyme, 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3), as a new target of ALK. Expression of PFKFB3 is highly dependent on ALK activity in ALK⁺ anaplastic large cell lymphoma and non-small-cell lung cancer (NSCLC) cells. Notably, ALK and PFKFB3 expressions exhibit significant correlation in clinic ALK⁺ NSCLC samples. We further demonstrated that ALK promotes PFKFB3 transcription through the downstream transcription factor STAT3. Upregulation of PFKFB3 by ALK is important for high glycolysis level as well as oncogenic activity of ALK⁺ lymphoma cells. Finally, targeting PFKFB3 by its inhibitor can overcome drug resistance in cells bearing TKI-resistant mutants of ALK. Collectively, our studies reveal a novel ALK-STAT3-PFKFB3 axis to promote cell proliferation and tumorigenesis, providing an alternative strategy for the treatment of ALK-positive tumors.

Anaplastic Large Cell Lymphoma: Molecular Pathogenesis and Treatment

Simple Summary

Anaplastic large cell lymphoma is a rare type of disease that occurs throughout the world and has four subtypes. A summary and comparison of these subtypes can assist with advancing our knowledge of the mechanism and treatment of ALCL, which is helpful in making progress in this field.

Abstract

Anaplastic large cell lymphoma (ALCL) is an uncommon type of non-Hodgkin’s lymphoma (NHL), as well as one of the subtypes of T cell lymphoma, accounting for 1 to 3% of non-Hodgkin’s lymphomas and around 15% of T cell lymphomas. In 2016, the World Health Organization (WHO) classified anaplastic large cell lymphoma into four categories: ALK-positive ALCL (ALK+ALCL), ALK-negative ALCL (ALK−ALCL), primary cutaneous ALCL (pcALCL), and breast-implant-associated ALCL (BIA-ALCL), respectively. Clinical symptoms, gene changes, prognoses, and therapy differ among the four types. Large lymphoid cells with copious cytoplasm and pleomorphic characteristics with horseshoe-shaped or reniform nuclei, for example, are found in both ALK+ and ALK−ALCL. However, their epidemiology and pathogenetic origins are distinct. BIA-ALCL is currently recognized as a new provisional entity, which is a noninvasive disease with favorable results. In this review, we focus on molecular pathogenesis and management of anaplastic large cell lymphoma.

ALK-positive anaplastic large cell lymphoma of skeletal muscle masquerading as soft tissue sarcoma

Anaplastic large cell lymphoma (ALCL) is a subtype of T cell non-Hodgkin's lymphoma and can present as an extranodal disease. Primary ALCL of skeletal muscle is rare. We report a case of ALK-positive ALCL involving the left thigh and anterior chest wall in a 12-year-old male child. The fine needle aspiration cytology from the lesion showed cellular smears with singly scattered and occasional clusters of large pleomorphic atypical cells. A diagnosis of poorly differentiated malignant neoplasm was rendered. On core biopsy, the histomorphological features posed a diagnostic challenge with a myriad of morphological mimickers. The diagnosis was established by excluding specific entities by relevant immunostains and confirming the diagnosis by strong expression of CD30 and ALK on immunohistochemistry. Fluorescence in-situ hybridisation confirmed the characteristic t(2:5) translocation. Presentation of ALCL with skeletal muscle involvement is uncommon, and the diagnosis relies on broadening the diagnostic possibilities and judicious use of immunohistochemical markers.

Detection of Gene Fusion Transcripts in Peripheral T-Cell Lymphoma Using a Multiplexed Targeted Sequencing Assay

The genetic basis of peripheral T-cell lymphoma (PTCL) is complex and encompasses several recurrent fusion transcripts discovered over the past years by means of massive parallel sequencing. However, there is currently no affordable and rapid technology for their simultaneous detection in clinical samples. Herein, we developed a multiplex ligation-dependent RT-PCR-based assay, followed by high-throughput sequencing, to detect 33 known PTCL-associated fusion transcripts. Anaplastic lymphoma kinase (ALK) fusion transcripts were detected in 15 of 16 ALK-positive anaplastic large-cell lymphomas. The latter case was further characterized by a novel SATB1_ALK fusion transcript. Among 239 other PTCLs, representative of nine entities, non-ALK fusion transcripts were detected in 24 samples, mostly of follicular helper T-cell (TFH) derivation. The most frequent non-ALK fusion transcript was ICOS_CD28 in nine TFH-PTCLs, one PTCL not otherwise specified, and one adult T-cell leukemia/lymphoma, followed by VAV1 rearrangements with multiple partners (STAP2, THAP4, MYO1F, and CD28) in five samples (three PTCL not otherwise specified and two TFH-PTCLs). The other rearrangements were CTLA4_CD28 (one TFH-PTCL), ITK_SYK (two TFH-PTCLs), ITK_FER (one TFH-PTCL), IKZF2_ERBB4 (one TFH-PTCL and one adult T-cell leukemia/lymphoma), and TP63_TBL1XR1 (one ALK-negative anaplastic large-cell lymphoma). All fusions detected by our assay were validated by conventional RT-PCR and Sanger sequencing in 30 samples with adequate material. The simplicity and robustness of this targeted multiplex assay make it an attractive tool for the characterization of these heterogeneous diseases.

NPM-ALK: A Driver of Lymphoma Pathogenesis and a Therapeutic Target

Simple Summary

Anaplastic lymphoma kinase (ALK) is a tyrosine kinase associated with Anaplastic Large Cell lymphoma (ALCL) through oncogenic translocations mainly NPM-ALK. Chemotherapy is effective in ALK(+) ALCL patients and induces remission rates of approximately 80%. The remaining patients do not respond to chemotherapy and some patients have drug-resistant relapses. Different classes of ALK tyrosine kinase inhibitors (TKI) are available but used exclusively for EML4-ALK (+) lung cancers. The significant toxicities of most ALK inhibitors explain the delay in their use in pediatric ALCL patients. Some ALCL patients do not respond to the first generation TKI or develop an acquired resistance. Combination therapy with ALK inhibitors in ALCL is the current challenge.

Abstract

Initially discovered in anaplastic large cell lymphoma (ALCL), the ALK anaplastic lymphoma kinase is a tyrosine kinase which is affected in lymphomas by oncogenic translocations, mainly NPM-ALK. To date, chemotherapy remains a viable option in ALCL patients with ALK translocations as it leads to remission rates of approximately 80%. However, the remaining patients do not respond to chemotherapy and some patients have drug-resistant relapses. It is therefore crucial to identify new and better treatment options. Nowadays, different classes of ALK tyrosine kinase inhibitors (TKI) are available and used exclusively for EML4-ALK (+) lung cancers. In fact, the significant toxicities of most ALK inhibitors explain the delay in their use in ALCL patients, who are predominantly children. Moreover, some ALCL patients do not respond to Crizotinib, the first generation TKI, or develop an acquired resistance months following an initial response. Combination therapy with ALK inhibitors in ALCL is the current challenge.

Colonic inflammatory myofibroblastic tumour presenting as 'pyrexia of unknown origin': report of a rare disease and its unique presentation

An intra-abdominal inflammatory myofibroblastic tumour (IMT) belongs to a rare group of diseases initially described as an inflammatory pseudotumour. Even though it is seen more often in children, its incidence in adults is even rarer. Clinical presentations can vary depending on its site and inherent tumour properties. The colon is an uncommon site for IMT and pyrexia of unknown origin (PUO) as its dominant clinical presentation is even rarer. A 27-year-old woman presented with PUO. She was evaluated under the department of internal medicine before undergoing an 18F-fluorodeoxyglucose positron emission tomography-computed tomography scan. This showed an intensely enhancing descending colon mass. An image-guided biopsy of this lesion was reported as IMT. She underwent a left hemicolectomy and complete excision of the tumour, following which her symptoms resolved completely. The patient has been disease-free at a 6-month follow-up and is asymptomatic at 1 year.

Minimal Residual Disease Monitoring Using a 3'ALK Universal Probe Assay in ALK-Positive Anaplastic Large-Cell Lymphoma: ddPCR, an Attractive Alternative Method to Real-Time Quantitative PCR

In ALK-positive anaplastic large-cell lymphomas, positive qualitative PCR for NPM1-anaplastic lymphoma kinase (ALK) in peripheral blood and/or bone marrow at diagnosis and during treatment are associated with a higher risk of treatment failure. Real-time quantitative PCR allows identification of very high risk patients. However, this latter technique initially designed for patients with lymphomas carrying the most frequent NPM1-ALK translocation necessitates calibration curves, limiting interlaboratory reproducibility. An ALK universal quantitative PCR based on 3'ALK transcript amplification was designed to allow the detection of all ALK fusion transcripts. The absolute concordance of 3'ALK quantitative PCR results were validated with the routine NPM1-ALK qualitative and quantitative PCR on 46 samples. The universality of ALK fusion transcript detection also was validated on TPM3-, ALO17-, and ATIC-ALK-positive samples, and the EML4-ALK-positive cell line. Digital droplet PCR using the 3'ALK universal probe showed highly concordant results with 3'ALK universal quantitative PCR. A major benefit of digital droplet PCR is a reduced experimental set-up compared with quantitative PCR, without generation of standard curves, leading to a reliable protocol for multilaboratory validation in multicenter clinical trials essential for this rare pathology. Our ALK universal method could be used for the screening of ALK fusion transcripts in liquid biopsy specimens of other ALK-positive tumors, including non-small cell lung carcinomas.

Crizotinib and Surgery for Long-Term Disease Control in Children and Adolescents With ALK-Positive Inflammatory Myofibroblastic Tumors

PURPOSE

Before anaplastic lymphoma kinase (ALK) inhibitors, treatment options for ALK-positive inflammatory myofibroblastic tumors (AP-IMTs) were unsatisfactory. We retrospectively analyzed the outcome of patients with AP-IMT treated with crizotinib to document response, toxicity, survival, and features associated with relapse.

METHODS

The cohort comprised eight patients with AP-IMT treated with crizotinib and surgery. Outcome measures were progression-free and overall survival after commencing crizotinib, treatment-related toxicities, features associated with relapse, outcome after relapse, and outcome after ceasing crizotinib.

RESULTS

The median follow-up after commencing crizotinib was 3 years (range, 0.9 to 5.5 years). The major toxicity was neutropenia. All patients responded to crizotinib. Five were able to discontinue therapy without recurrence (median treatment duration, 1 year; range, 0.2 to 3.0 years); one continues on crizotinib. Two critically ill patients with initial complete response experienced relapse while on therapy. Both harbored RANBP2-ALK fusions and responded to alternative ALK inhibitors; one ultimately died as a result of progressive disease, whereas the other remains alive on treatment. Progression-free and overall survival since commencement of crizotinib is 0.75 ± 0.15% and 0.83 ± 0.15%, respectively.

CONCLUSION

We confirm acceptable toxicity and excellent disease control in patients with AP-IMT treated with crizotinib, which may be ceased without recurrence in most. Relapses occurred in two of three patients with RANBP2-ALK translocated IMT, which suggests that such patients require additional therapy.

Discovery Stories of RET Fusions in Lung Cancer: A Mini-Review

In 2004, a chemical inhibitor of the kinase activity of EGFR was reported to be effective in a subset of lung cancer patients with activating somatic mutations of EGFR. It remained unclear, however, whether kinase fusion genes also play a major role in the pathogenesis of lung cancers. The discovery of the EML4-ALK fusion kinase in 2007 was a breakthrough for this situation, and kinase fusion genes now form a group of relevant targetable oncogenes in lung cancer. In this mini-review article, the discovery of REarrangement during Transfection fusions, the third kinase fusion gene in lung cancer, is briefly described.

The Pathological Spectrum of Systemic Anaplastic Large Cell Lymphoma (ALCL)

Anaplastic large cell lymphoma (ALCL) represents a group of malignant T-cell lymphoproliferations that share morphological and immunophenotypical features, namely strong CD30 expression and variable loss of T-cell markers, but differ in clinical presentation and prognosis. The recognition of anaplastic lymphoma kinase (ALK) fusion proteins as a result of chromosomal translocations or inversions was the starting point for the distinction of different subgroups of ALCL. According to their distinct clinical settings and molecular findings, the 2016 revised World Health Organization (WHO) classification recognizes four different entities: systemic ALK-positive ALCL (ALK+ ALCL), systemic ALK-negative ALCL (ALK− ALCL), primary cutaneous ALCL (pC-ALCL), and breast implant-associated ALCL (BI-ALCL), the latter included as a provisional entity. ALK is rearranged in approximately 80% of systemic ALCL cases with one of its partner genes, most commonly NPM1, and is associated with favorable prognosis, whereas systemic ALK− ALCL shows heterogeneous clinical, phenotypical, and genetic features, underlining the different oncogenesis between these two entities. Recognition of the pathological spectrum of ALCL is crucial to understand its pathogenesis and its boundaries with other entities. In this review, we will focus on the morphological, immunophenotypical, and molecular features of systemic ALK+ and ALK− ALCL. In addition, BI-ALCL will be discussed.

Tumor Resistance against ALK Targeted Therapy-Where It Comes From and Where It Goes

Anaplastic lymphoma kinase (ALK) is a validated molecular target in several ALK-rearranged malignancies, particularly in non-small-cell lung cancer (NSCLC), which has generated considerable interest and effort in developing ALK tyrosine kinase inhibitors (TKI). Crizotinib was the first ALK inhibitor to receive FDA approval for ALK-positive NSCLC patients treatment. However, the clinical benefit observed in targeting ALK in NSCLC is almost universally limited by the emergence of drug resistance with a median of occurrence of approximately 10 months after the initiation of therapy. Thus, to overcome crizotinib resistance, second/third-generation ALK inhibitors have been developed and received, or are close to receiving, FDA approval. However, even when treated with these new inhibitors tumors became resistant, both in vitro and in clinical settings. The elucidation of the diverse mechanisms through which resistance to ALK TKI emerges, has informed the design of novel therapeutic strategies to improve patients disease outcome. This review summarizes the currently available knowledge regarding ALK physiologic function/structure and neoplastic transforming role, as well as an update on ALK inhibitors and resistance mechanisms along with possible therapeutic strategies that may overcome the development of resistance.

Anaplastic lymphoma kinase aberrations correlate with metastatic features in pediatric rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is the most frequent soft tissue tumor in childhood and arises from immature mesenchymal cells committed to skeletal muscle differentiation. Anaplastic Lymphoma Kinase (ALK) is a receptor tyrosine kinase aberrantly expressed in several cancers. Moreover, ALK full-length receptor protein has been observed in RMS, although its clinical and functional significance is yet controversial. The role of ALK and its clinical relevance were investigated in a selected cohort of 74 FFPE pediatric RMS and a panel of RMS cell lines, evaluating its gene and protein status, utilizing Fluorescent In Situ Hybridization (FISH), immunohistochemistry (IHC) and Western blot approaches. Moreover, to get insight into its possible therapeutic relevance, effects of ALK silencing on cell proliferation, invasion and apoptosis were studied in RMS cells. ALK IHC positivity was significantly correlated with gene copy number gain, the alveolar subtype, PAX3/7-FOXO1 rearrangements, the presence of metastasis at diagnosis and a worse overall outcome. Furthermore, EML4-ALK fusion gene associated with higher protein expression was identified in an embryonal RMS. ALK silencing in RH30 ALK positive cells strongly inhibited invasion capability. Overall, our data suggest a potential role of ALK in pediatric RMS.

ALK expression plays different roles in anaplastic large-cell lymphomas and outcome of crizotinib use in relapsed/refractory ALK+ patients in a Chinese population

The prognostic value of anaplastic lymphoma kinase (ALK) expression in patients with anaplastic large-cell lymphoma (ALCL) remains controversial. Data on the clinical features of ALCL in a Chinese population are limited. We retrospectively reviewed 1293 patients with pathologically diagnosed lymphoma at Guangdong General Hospital from June 2007 through August 2016. We evaluated the incidence of ALCL, clinical characteristics, survival status, and outcome of crizotinib use in four relapsed/refractory ALK-positive patients. Among the 1293 patients, 1193 (92.3%) were non-Hodgkin's lymphoma, and 53 (4.4%) of whom were ALCL. Of the 50 ALCL patients, with a median age of 34 years, were evaluated. Among them, 33 (66.0%) were ALK-positive and 17 (34.0%) were ALK-negative. Significantly, more patients younger than 40 years old were ALK-positive than ALK-negative (66.7 vs. 23.5%; P = 0.003). The 5-year progression-free survival (PFS) for ALK-positive and ALK-negative patients were 61 and 11%, and the 5-year overall survival (OS) were 70 and 22%, respectively. Median PFS and OS were significantly better for patients with ALK-positive than ALK-negative (60.1 vs. 9.4 months, P = 0. 017; not reached vs. 32.7 months, P = 0.021). Multivariate analyses identified ALK expression, stage, and bone marrow involvement as independent prognostic factors for PFS and OS. Four relapsed ALK-positive patients were treated with crizotinib and two died. Our results suggest that ALK expression has different prognostic significance in patients with ALCL. Mechanisms underlying early relapse after chemotherapy and resistance to crizotinib need further investigation.

Targeting ALK: Precision Medicine Takes on Drug Resistance

Anaplastic lymphoma kinase (ALK) is a validated molecular target in several ALK-rearranged malignancies, including non-small cell lung cancer. However, the clinical benefit of targeting ALK using tyrosine kinase inhibitors (TKI) is almost universally limited by the emergence of drug resistance. Diverse mechanisms of resistance to ALK TKIs have now been discovered, and these basic mechanisms are informing the development of novel therapeutic strategies to overcome resistance in the clinic. In this review, we summarize the current successes and challenges of targeting ALK.

SIGNIFICANCE

Effective long-term treatment of ALK-rearranged cancers requires a mechanistic understanding of resistance to ALK TKIs so that rational therapies can be selected to combat resistance. This review underscores the importance of serial biopsies in capturing the dynamic therapeutic vulnerabilities within a patient's tumor and offers a perspective into the complexity of on-target and off-target ALK TKI resistance mechanisms. Therapeutic strategies that can successfully overcome, and potentially prevent, these resistance mechanisms will have the greatest impact on patient outcome. Cancer Discov; 7(2); 137-55. ©2017 AACR.

Subcellular Localization of Immunohistochemical Signals

In the literature, sufficient attention has not been paid to the precise subcellular localization of immunohistochemical signals, the knowledge of which is essential for proper interpretation of immunostains and distinction of genuine staining from biotin-associated or other nonspecific stainings. The subcellular localization of the signals can in fact be easily deduced from the known biologic or ultrastructural characteristics of the antigens. Extracellular antigens obviously are located in the extracellular compartment. Cellular antigens fall into 3 major groups: membranous, nuclear, and cytoplasmic. Membranous antigens include cell adhesion molecules (such as E-cadherin, N-CAM), cell surface/transmembrane receptors and proteins (such as tyrosine kinase receptors, most leukocyte antigens, CD10, CEA), and molecules linking surface molecules to cytoskeleton (such as β-catenin, dystrophin). Nuclear antigens include cell cycle-associated proteins (such as cyclins, p16, Ki-67), nuclear enzymes (such as TdT), transcription factors (such as TTF-1, CDX-2, myogenin, PAX-5), tumor suppressor gene products (such as p53, p63, WT1, Rb), steroid hormone receptors (such as ER, PR), calcium-binding proteins (such as S-100 protein, calretinin), and some viral proteins (such as CMV, herpes). Cytoplasmic antigens can take up a granular pattern due to localization in organelles, granules, or secretory vesicles (such as chromogranin, hormones, lysozyme, HMB-45), fibrillary pattern attributable to the filamentous nature of the molecules (intermediate filaments and microfilaments), or diffuse or patchy pattern due to localization in the cytosol or large vesicles (such as myoglobin, albumin, thyroglobulin). Aberrant localization of the molecules, when present, can provide important insight into disease processes and aid in their diagnosis, such as loss of membranous E-cadherin expression in lobular breast carcinoma, aberrant nuclear localization of β-catenin in colorectal adenocarcinoma, pattern of ALK staining in anaplastic large cell lymphoma correlating with the different types of chromosomal translocations, presence of additional cytoplasmic CD10 staining in the enterocytes indicative of microvillous inclusion disease, and “reversed” staining for EMA in micropapillary mammary carcinoma.

Molecular genetics of childhood, adolescent and young adult non-Hodgkin lymphoma

Molecular genetic abnormalities are ubiquitous in non-Hodgkin lymphoma (NHL), but genetic changes are not yet used to define specific lymphoma subtypes. Certain recurrent molecular genetic abnormalities in NHL underlie molecular pathogenesis and/or are associated with prognosis or represent potential therapeutic targets. Most molecular genetic studies of B- and T-NHL have been performed on adult patient samples, and the relevance of many of these findings for childhood, adolescent and young adult NHL remains to be demonstrated. In this review, we focus on NHL subtypes that are most common in young patients and emphasize features actually studied in younger NHL patients. This approach highlights what is known about NHL genetics in young patients but also points to gaps that remain, which will require cooperative efforts to collect and share biological specimens for genomic and genetic analyses in order to help predict outcomes and guide therapy in the future.

Anaplastic large cell lymphoma in paediatric and young adult patients

Anaplastic large cell lymphoma (ALCL) is a heterogeneous disease of debateable origin that, in children, is largely anaplastic lymphoma kinase (ALK) positive with aberrant ALK activity induced following the formation of chromosomal translocations. Whilst the survival rates for this disease are relatively high, a significant proportion (20-40%) of patients suffer disease relapse, in some cases on multiple occasions and therefore suffer the toxic side-effects of combination chemotherapy. Traditionally, patients are treated with a combination of agents although recent data from relapse patients have suggested that low risk patients might benefit from single agent vinblastine and, going forward, the addition of ALK inhibitors to the therapeutic regimen may have beneficial consequences. There are also a plethora of other drugs that might be advantageous to patients with ALCL and many of these have been identified through laboratory research although the decision as to which drugs to implement in trials will not be trivial.

Adult systemic anaplastic large-cell lymphoma: recommendations for diagnosis and management

Systemic anaplastic large-cell lymphomas (sALCLs) comprise a heterogeneous group of relatively rare T-cell non-Hodgkin lymphomas (NHLs) characterized by CD30 expression and other unifying pathologic features. Anaplastic lymphoma kinase (ALK) fusions are present in about 50% of cases. Pathological diagnosis can be challenging, particularly in ALK-negative cases. Though ALK-positive and ALK-negative sALCLs are similar morphologically and immunophenotypically, they are separate entities with different genetics, clinical behavior, and outcomes. Evidence-based data evaluating treatment regimens are limited as randomized controlled trials are lacking and most prospective studies are too small to draw definitive conclusions. However, recent advances in molecular biology are bringing forth much-needed knowledge in this field, and are likely to guide further targeted therapeutic development.

Novel ALK inhibitors in clinical use and development

Anaplastic lymphoma kinase 1 (ALK-1) is a member of the insulin receptor tyrosine kinase family. ALK-1 was initially found in anaplastic large cell lymphoma (ALCL). ALK mutations have also been implicated in the pathogenesis of non-small cell lung cancer (NSCLC) and other solid tumors. Multiple small molecule inhibitors with activity against ALK and related oncoproteins are under clinical development. Two of them, crizotinib and ceritinib, have been approved by FDA for treatment of locally advanced and metastatic NSCLC. More agents (alectinib, ASP3026, X396) with improved safety, selectivity, and potency are in the pipeline. Dual inhibitors targeting ALK and EGFRm (AP26113), TRK (TSR011), FAK (CEP-37440), or ROS1 (RXDX-101, PF-06463922) are under active clinical development.

Advances in understanding the pathogenesis of systemic anaplastic large cell lymphomas

The currently used 2008 World Health Organization classification recognizes two types of systemic anaplastic large T cell lymphoma according to ALK protein expression in tumour cells. First, the 'anaplastic large cell lymphoma, ALK positive' (ALK(+) ALCL) that is characterized by the presence of ALK gene rearrangements and consequent ALK protein expression, and, second, the 'anaplastic large cell lymphoma, ALK negative' (ALK(-) ALCL) that is a provisional entity lacking ALK protein expression but cannot be distinguished morphologically from ALK(+) ALCL. In this review we summarize the current knowledge on the genetic lesions and biological features that underlie the pathogenesis of ALK(+) and the ALK(-) ALCL and that can lead to the use of targeted anti-cancer agents.

Anaplastic large cell lymphomas: ALK positive, ALK negative, and primary cutaneous

Anaplastic large cell lymphomas (ALCLs) comprise a group of CD30-positive non-Hodgkin lymphomas that generally are of T-cell origin and share common morphologic and phenotypic characteristics. The World Health Organization recognizes 3 entities: primary cutaneous ALCL (pcALCL), anaplastic lymphoma kinase (ALK)-positive ALCL, and, provisionally, ALK-negative ALCL. Despite overlapping pathologic features, these tumors differ in clinical behavior and genetics. pcALCL presents in the skin and, while it may involve locoregional lymph nodes, rarely disseminates. Outcomes typically are excellent. ALK-positive ALCL and ALK-negative ALCL are systemic diseases. ALK-positive ALCLs consistently have chromosomal rearrangements involving the ALK gene with varied gene partners, and generally have a favorable prognosis. ALK-negative ALCLs lack ALK rearrangements and their genetic and clinical features are more variable. A subset of ALK-negative ALCLs has rearrangements in or near the DUSP22 gene and has a favorable prognosis similar to that of ALK-positive ALCL. DUSP22 rearrangements also are seen in a subset of pcALCLs. In this review, we discuss the clinical, morphologic, phenotypic, genetic, and biological features of ALCLs.

Inflammatory myofibroblastic tumors of the urinary bladder: a systematic review

We systemically reviewed the literature on inflammatory myofibroblastic tumors (IMTs) of the urinary bladder and compared between anaplastic lymphoma kinase (ALK)-positive and ALK-negative IMTs. An extensive search of the literature was performed in Medline and Web of Science using the following terms: "inflammatory myofibrolastic tumor," "inflammatory pseudotumor," and "bladder." A manual search was also performed using the web-based search engine Google Scholar. Reference lists of the retrieved articles were reviewed for other relevant studies. Patients' and disease characteristics of each individual case were reviewed. Further analyses were performed to compare between ALK-positive and ALK-negative IMTs. Forty-one studies were identified, and 182 patients were included for review and subsequent analyses. Of the IMTs, 65% were ALK-positive. Local tumor recurrence rate was 4%, and no cases of distant metastases have been reported. Compared with ALK-negative IMTs, ALK-positive IMTs had a female predilection with a sex ratio (male:female) of 1:1.67 (P = .048). ALK-positive IMTs also appeared to occur in younger patients (P = .072). No significant differences were noted in terms of their clinical presentations and histologic features. On immunohistochemical staining, ALK-positive IMTs had more positive results for desmin (P = .042) and p53 (P = .05), and more negative results for clusterin (P = .003). In summary, ALK-positive IMTs of the urinary bladder had a female predilection, appeared to occur more frequently in younger patients, and had different immunohistochemical staining patterns when compared with ALK-negative IMTs. Regardless of its ALK status, IMT of the urinary bladder has a good prognosis after surgical resection.

ALK-positive cancer: still a growing entity

 Since the discovery of ALK-positive anaplastic large-cell lymphoma in 1994 many other types of tumors showing ALK expression were disclosed. They form a heterogeneous group, including lung, renal and soft tissue tumors. The biological function of ALK, its role in carcinogenesis and impact exerted on the clinical outcome have been studied by many research groups. New drugs specifically dedicated for ALK inhibition, for example, crizotinib, have been synthesized and have become a viable treatment option for ALK-positive lung adenocarcinoma, and potentially for other ALK-positive cancers. This review summarizes the current state of knowledge concerning ALK-positive neoplasms, focusing on the clinical aspects of the subject.

Detection of ALK rearrangement by immunohistochemistry in lung adenocarcinoma and the identification of a novel EML4-ALK variant

INTRODUCTION

The echinoderm microtubule-associated protein-like 4 anaplastic lymphoma kinase (EML4-ALK) fusion gene has been identified as a potent oncogenic driver in non-small-cell lung cancer, in particular adenocarcinoma (ADC). It defines a unique subgroup of lung ADC, which may be responsive to ALK inhibitors. Detection of ALK rearrangement by fluorescence in situ hybridization (FISH) or reverse transcriptase polymerase chain reaction (RT-PCR) is considered to be the standard procedure, but each with its own limitation. We evaluated the practical usefulness of immunohistochemistry (IHC) to detect ALK expression as a reliable detection method of ALK rearrangement in lung ADC.

METHODS

We tested 373 lung ADCs for ALK rearrangement by IHC and FISH. Multiplex RT-PCR was performed to confirm the fusion variants.

RESULTS

Twenty-two of 373 lung ACs (5.9%) were positive for ALK immunoreactivity. ALK-positive tumor cells demonstrated strong and diffused granular staining in the cytoplasm. All the ALK IHC-positive cases were confirmed to harbor ALK rearrangement, either by FISH, or RT-PCR. Two cases with positive ALK protein expression, but negative for breakapart FISH signal were shown to harbor EML4-ALK variant 1 by RT-PCR. None of the ALK IHC-negative cases were FISH-positive. In addition, we identified a novel EML4-ALK fusion variant (E3:ins53A20), and its potent transformation potential has been confirmed by in vivo tumorigenicity assay.

CONCLUSION

IHC can effectively detect ALK rearrangement in lung cancer. It might provide a reliable and cost-effective diagnostic approach in routine pathologic laboratories for the identification of suitable candidates for ALK-targeted therapy.

Molecular diagnostics of T-cell lymphoproliferative disorders

T-cell neoplasms include both mature T-cell leukemias and lymphomas and immature proliferations of precursor T cells. Molecular laboratories routinely assay suspected T-cell proliferations for evidence of clonality. In addition, some T-cell neoplasms are characterized by recurrent structural abnormalities that can be readily identified by such techniques as fluorescence in situ hybridization. New massively parallel sequencing technologies have led to the identification of numerous recurrent gene mutations in T-cell neoplasms. These findings are reviewed. As new technologies become implemented in molecular diagnostic laboratories and as targeted therapies are developed, it is anticipated that more extensive genomic characterization of T-cell neoplasms will be routinely performed in the future.

Anaplastic lymphoma kinase (ALK) inhibitors: a review of design and discovery

This review elucidates the hit-to-drug evolution design of three ALK inhibitors.

CLTC-ALK fusion as a primary event in congenital blastic plasmacytoid dendritic cell neoplasm

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a subtype of acute myeloid leukemia, affecting mainly the elderly. It is thought to be derived from plasmacytoid dendritic cell precursors, which frequently present as cutaneous lesions. We have made a detailed analysis of an infant with BPDCN, who manifested with hemophagocytic lymphohistiocytosis. The peripheral blood leukocytes revealed the t(2;17;8)(p23;q23;p23) translocation and a CLTC-ALK fusion gene, which have never been reported in BPDCN or in any myeloid malignancies thus far. Neonatal blood spots on the patient's Guthrie card were analyzed for the presence of the CLTC-ALK fusion gene, identifying the in utero origin of the leukemic cell. Although the leukemic cells were positive for CD4, CD56, CD123, and CD303, indicating a plasmacytoid dendritic cell phenotype, detailed analysis of the lineage distribution of CLTC-ALK revealed that part of monocytes, neutrophils, and T cells possessed the fusion gene and were involved in the leukemic clone. These results indicated that leukemic cells with CLTC-ALK originated in a multipotent hematopoietic progenitor in utero. This is the first report of the CLTC-ALK fusion gene being associated with a myeloid malignancy, which may give us an important clue to the origin of this rare neoplasm.

A novel ALK rearrangement in an inflammatory myofibroblastic tumor in a neonate

Inflammatory myofibroblastic tumors (IMTs) are uncommon lesions primarily affecting children and young adults. They have rarely been described in infants, with a very small number described in neonates. Structural rearrangements in the anaplastic large-cell lymphoma kinase gene (ALK) has contributed to our categorizing this lesion as a neoplasm. In addition, rearrangements of the ALK gene have been implicated in the pathogenicity of many other hematolymphoid and non-hematolymphoid tumors, typically involving 2p23 with different partners or with pericentric inversion. We report a previously undescribed cryptic deletion and intrachromosomal-insertional translocation of the 3'-region of the ALK gene from 2p23 to the 2q33-q35 in an IMT of a newborn patient with an apparently normal G-band karyotype of the tumor.

Mechanistic insight into ALK receptor tyrosine kinase in human cancer biology

The burgeoning field of anaplastic lymphoma kinase (ALK) in cancer encompasses many cancer types, from very rare cancers to the more prevalent non-small-cell lung cancer (NSCLC). The common activation of ALK has led to the use of the ALK tyrosine kinase inhibitor (TKI) crizotinib in a range of patient populations and to the rapid development of second-generation drugs targeting ALK. In this Review, we discuss our current understanding of ALK function in human cancer and the implications for tumour treatment.

Anaplastic lymphoma kinase as a therapeutic target

INTRODUCTION

Anaplastic lymphoma kinase (ALK), a tyrosine kinase receptor, has been initially identified through its involvement in chromosomal translocations associated with anaplastic large cell lymphoma. However, recent evidence that aberrant ALK activity is also involved in an expanding number of tumor types, such as other lymphomas, inflammatory myofibroblastic tumor, neuroblastomas and some carcinomas, including non-small cell lung carcinomas, is boosting research progress in ALK-targeted therapies.

AREAS COVERED

The first aim of this review is to describe current understandings about the ALK tyrosine kinase and its implication in the oncogenesis of human cancers as a fusion protein or through mutations. The second goal is to discuss its interest as a therapeutic target and to provide a review of the literature regarding ALK inhibitors. Mechanisms of acquired resistance are also reviewed.

EXPERT OPINION

Several ALK inhibitors have recently been developed, offering new treatment options in tumors driven by abnormal ALK signaling. However, as observed with other tyrosine kinase inhibitors, resistance has emerged in patients treated with these agents. The complexity of mechanisms of acquired resistance recently described suggests that other therapeutic options, including combination of ALK and other kinases targeted drugs, will be required in the future.

NPM-ALK: The Prototypic Member of a Family of Oncogenic Fusion Tyrosine Kinases

Anaplastic lymphoma kinase (ALK) was first identified in 1994 with the discovery that the gene encoding for this kinase was involved in the t(2;5)(p23;q35) chromosomal translocation observed in a subset of anaplastic large cell lymphoma (ALCL). The NPM-ALK fusion protein generated by this translocation is a constitutively active tyrosine kinase, and much research has focused on characterizing the signalling pathways and cellular activities this oncoprotein regulates in ALCL. We now know about the existence of nearly 20 distinct ALK translocation partners, and the fusion proteins resulting from these translocations play a critical role in the pathogenesis of a variety of cancers including subsets of large B-cell lymphomas, nonsmall cell lung carcinomas, and inflammatory myofibroblastic tumours. Moreover, the inhibition of ALK has been shown to be an effective treatment strategy in some of these malignancies. In this paper we will highlight malignancies where ALK translocations have been identified and discuss why ALK fusion proteins are constitutively active tyrosine kinases. Finally, using ALCL as an example, we will examine three key signalling pathways activated by NPM-ALK that contribute to proliferation and survival in ALCL.

Tyrosine kinase gene fusions in cancer: translating mechanisms into targeted therapies

Tyrosine kinase fusion genes represent an important class of oncogenes associated with leukaemia and solid tumours. They are produced by translocations and other chromosomal rearrangements of a subset of tyrosine kinase genes, including ABL, PDGFRA, PDGFRB, FGFR1, SYK, RET, JAK2 and ALK. Based on recent findings, this review discusses the common mechanisms of activation of these fusion genes. Enforced oligomerization and inactivation of inhibitory domains are the two key processes that switch on the kinase domain. Activated tyrosine kinase fusions then signal via an array of transduction cascades, which are largely shared. In addition, the fusion partner provides a scaffold for the recruitment of proteins that contribute to signalling, protein stability, cellular localization and oligomerization. The expression level of the fusion protein is another critical parameter. Its transcription is controlled by the partner gene promoter, while translation may be regulated by miRNA. Several mechanisms also prevent the degradation of the oncoprotein by proteasomes and lysosomes, leading to its accumulation in cells. The selective inhibition of the tyrosine kinase activity by adenosine-5'-triphosphate competitors, such as imatinib, is a major therapeutic success. Imatinib induces remission in leukaemia patients that are positive for BCR-ABL or PDGFR fusions. Recently, crizotinib produced promising results in a subtype of lung cancers with ALK fusion. However, resistance was reported in both cases, partially due to mutations. To tackle this problem, additional levels of therapeutic interventions are suggested by the complex mechanisms of fusion tyrosine kinase activation. New approaches include allosteric inhibition and interfering with oligomerization or chaperones.

RNASET2--an autoantigen in anaplastic large cell lymphoma identified by protein array analysis

Characterising tumour-associated antigens (TAAs) not only represents an important approach to the identification of new diagnostic/prognostic markers, but can also provide information on disease processes and additional potential therapeutic targets. Preliminary screening of a protein macroarray, containing more than 12,000 different proteins, with sera from anaplastic lymphoma kinase (ALK)-negative and ALK-positive anaplastic large cell lymphoma (ALCL) patients identified ribonuclease and tumour suppressor protein Ribonuclease T2 (RNASET2), phosphatase lipid phosphate phosphatase-related protein type 3 (LPPR3) and apoptotic adaptor molecule Fas-associating protein (FADD) as ALK-negative ALCL-associated TAAs. Further validation of these observations was confirmed using the ALCL sera in reverse ELISAs. The circulating anti-RNASET2 autoantibodies present in ALCL patients' sera also recognised eukaryotically expressed RNASET2 protein. RNASET2 expression was then investigated in normal tissues and in lymphomas to explore its clinical potential. RNASET2 protein and mRNA levels showed highest expression in the spleen, leucocytes and pancreas. RNASET2 protein expression was not restricted to ALK-negative ALCL (81%), being expressed in ALK-positive ALCL (65%) as well as in a number of other lymphomas. The immunological recognition of RNASET2, its expression in ALCL and other lymphomas together with its known tumourigenic properties suggest that further studies on this autoantigen are warranted.

Inhibitors of the anaplastic lymphoma kinase

INTRODUCTION

Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase normally expressed in the developing nervous tissue. Genetic alterations of ALK are associated with a number of cancers, including anaplastic large cell lymphoma (ALCL) and a subset of non-small cell lung cancer (NSCLC). Standard therapies for these diseases include surgery plus unspecific cytotoxic agents, with a low therapeutic window and significant treatment-associated systemic toxicity. A few small-molecule inhibitors of ALK kinase activity have been described in the recent years, some of which are currently undergoing clinical evaluation.

AREAS COVERED

Literature was searched for all ALK inhibitors that have entered clinical investigation, including published research articles and meeting abstracts. Data on pharmacokinetics, safety and efficacy of crizotinib, as well as preliminary clinical data for second-generation compounds, are reviewed. The issue of drug resistance is discussed.

EXPERT OPINION

Understanding the specific genetic aberration that causes cancer development and progression allows major advances in cancer therapy. Along the same way shown by imatinib in chronic myeloid leukemia, compounds that selectively target ALK are bringing a revolution in the treatment of ALK-positive tumors. Crizotinib has just been approved, and new more potent ALK inhibitors will shortly follow. These molecules represent another excellent proof-of-principle for targeted therapy.

Pediatric T- and NK-cell lymphomas: new biologic insights and treatment strategies

T- and natural killer (NK)-cell lymphomas are challenging childhood neoplasms. These cancers have varying presentations, vast molecular heterogeneity, and several are quite unusual in the West, creating diagnostic challenges. Over 20 distinct T- and NK-cell neoplasms are recognized by the 2008 World Health Organization classification, demonstrating the diversity and potential complexity of these cases. In pediatric populations, selection of optimal therapy poses an additional quandary, as most of these malignancies have not been studied in large randomized clinical trials. Despite their rarity, exciting molecular discoveries are yielding insights into these clinicopathologic entities, improving the accuracy of our diagnoses of these cancers, and expanding our ability to effectively treat them, including the use of new targeted therapies. Here, we summarize this fascinating group of lymphomas, with particular attention to the three most common subtypes: T-lymphoblastic lymphoma, anaplastic large cell lymphoma, and peripheral T-cell lymphoma-not otherwise specified. We highlight recent findings regarding their molecular etiologies, new biologic markers, and cutting-edge therapeutic strategies applied to this intriguing class of neoplasms.

KLC1-ALK: a novel fusion in lung cancer identified using a formalin-fixed paraffin-embedded tissue only

The promising results of anaplastic lymphoma kinase (ALK) inhibitors have changed the significance of ALK fusions in several types of cancer. These fusions are no longer mere research targets or diagnostic markers, but they are now directly linked to the therapeutic benefit of patients. However, most available tumor tissues in clinical settings are formalin-fixed and paraffin-embedded (FFPE), and this significantly limits detailed genetic studies in many clinical cases. Although recent technical improvements have allowed the analysis of some known mutations in FFPE tissues, identifying unknown fusion genes by using only FFPE tissues remains difficult. We developed a 5′-rapid amplification of cDNA ends-based system optimized for FFPE tissues and evaluated this system on a lung cancer tissue with ALK rearrangement and without the 2 known ALK fusions EML4-ALK and KIF5B-ALK. With this system, we successfully identified a novel ALK fusion, KLC1-ALK. The result was confirmed by reverse transcription-polymerase chain reaction and fluorescence in situ hybridization. Then, we synthesized the putative full-length cDNA of KLC1-ALK and demonstrated the transforming potential of the fusion kinase with assays using mouse 3T3 cells. To the best of our knowledge, KLC1-ALK is the first novel oncogenic fusion identified using only FFPE tissues. This finding will broaden the potential value of archival FFPE tissues and provide further biological and clinical insights into ALK-positive lung cancer.

Anaplastic large-cell lymphoma

The concept of anaplastic large-cell lymphoma (ALCL) has changed over the years because of a stream of new information and novel understanding regarding the cell of origin, biology, genetics, and clinical features of these neoplasms. This new information has led to the current classification proposed by the expert reviewers of the World Health Organization. The objective of this review is to present the most updated information on the cytologic and histologic features of these entities, with a special reference to diagnostic algorithms. A detailed description of the genetic aberrations and the pathogenetic mechanisms leading to transformation is presented. The clinical features of ALCL and novel tailored strategies are briefly illustrated.

Targeting oncogenic ALK: a promising strategy for cancer treatment

Recently, the anaplastic lymphoma kinase (ALK) has been found to be altered in several solid and hematologic tumors. Novel drugs targeting this tyrosine kinase receptor are under development, and early clinical trials are showing promising activity in non-small cell lung cancer patients with ALK+ tumors. Here, we review the structure and function of the ALK receptor, the mechanisms associated with its deregulation in cancer, methods for ALK detection in tumor samples, its potential as a new marker for candidate patient selection for tailored therapy, and novel drugs under development that target ALK.

Anaplastic lymphoma kinase in human cancer

The receptor tyrosine kinases (RTKs) play a critical role, controlling cell proliferation, survival, and differentiation of normal cells. Their pivotal function has been firmly established in the pathogenesis of many cancers as well. The anaplastic lymphoma kinase (ALK), a transmembrane RTK, originally identified in the nucleophosmin (NPM)-ALK chimera of anaplastic large cell lymphoma, has emerged as a novel tumorigenic player in several human cancers. In this review, we describe the expression of the ALK-RTK, its related fusion proteins, and their molecular mechanisms of activation. Novel tailored strategies are briefly illustrated for the treatment of ALK-positive neoplasms.