Crizotinib resistance in acute myeloid leukemia with inv(2)(p23q13)/RAN binding protein 2 (RANBP2) anaplastic lymphoma kinase (ALK) fusion and monosomy 7

Complete morphologic response to gilteritinib in ALK-rearranged acute myeloid leukemia

The cytogenetic abnormality inv(2)(p23q13) in acute myeloid leukemia (AML) results in a fusion of RANBP2 with ALK. This fusion makes ALK constitutively active and acts as a driver for the proliferation of AML cell lines. Gilteritinib, a FLT3 inhibitor approved in AML, also can inhibit ALK among other receptor tyrosine kinases. A 75-year-old-woman with a history of essential thrombocythemia (ET) and a presumed germline DDX41 mutation developed ALK-fusion positive AML and despite standard therapies was transfusion-dependent and globally declining. The patient has been on gilteritinib with an ongoing response of more than one year with near normal blood counts and no evidence of AML. The fact that she was found to harbor a presumed germline DDX41 alteration may account for why she developed, and yet survived, two myeloid neoplasms (ET and AML). Additionally, this demonstrates that gilteritinib is clinically active as an ALK inhibitor, and could be considered for use in any AML patient presenting with an inv(2(p23q13)) translocation. Finally, it is an example of using a disease-agnostic, precision medicine approach to arrive at a beneficial treatment.

ALK Fusion in an Adolescent with Acute Myeloid Leukemia: A Case Report and Review of the Literature

Activating mutations and fusions of the ALK oncogene have been identified as drivers in a number of malignancies. Crizotinib and subsequent ALK tyrosine kinase inhibitors have improved treatment outcomes for these patients. In this paper, we discuss the case of an adolescent patient with acute myeloid leukemia, who was identified to have an activating ALK fusion, which is a rare finding and has never been reported in cases of AML without monosomy 7. Crizotinib was added to this patient's frontline therapy and was well tolerated. In cases of more common gene alterations, existing data supports the use of targeted agents as post-HSCT maintenance therapy; however, crizotinib was not able to be used post-HSCT for this patient due to the inability to obtain insurance coverage.

Functional consequence and therapeutic targeting of cryptic ALK fusions in monosomy 7 acute myeloid leukemia

Acute myeloid leukemia (AML) patients have a wide array of cytogenetic and molecular aberrations, which can influence response to therapy. Monosomy 7 is a rare subset within pediatric AML (prevalence of <2%) that is highly associated with poor outcomes. Fusions involving the anaplastic tyrosine kinase (ALK) gene were exclusively identified in 14.3% of this high-risk cohort, while absent across all other AML. Given the dismal outcomes of monosomy 7, we evaluated the use of crizotinib, an FDA-approved tyrosine kinase inhibitor, used to treat patients with ALK fusions. Our findings suggest that crizotinib may serve as a novel therapy for these patients.

The SUMO Pathway in Hematomalignancies and Their Response to Therapies

SUMO (Small Ubiquitin-related MOdifier) is a post-translational modifier of the ubiquitin family controlling the function and fate of thousands of proteins. SUMOylation is deregulated in various hematological malignancies, where it participates in both tumorigenesis and cancer cell response to therapies. This is the case for Acute Promyelocytic Leukemias (APL) where SUMOylation, and subsequent destruction, of the PML-RARα fusion oncoprotein are triggered by arsenic trioxide, which is used as front-line therapy in combination with retinoic acid to cure APL patients. A similar arsenic-induced SUMO-dependent degradation was also documented for Tax, a human T-cell lymphotropic virus type I (HTLV1) viral protein implicated in Adult T-cell Leukemogenesis. SUMOylation also participates in Acute Myeloid Leukemia (AML) response to both chemo- and differentiation therapies, in particular through its ability to regulate gene expression. In Multiple Myeloma, many enzymes of the SUMO pathway are overexpressed and their high expression correlates with lower response to melphalan-based chemotherapies. B-cell lymphomas overexpressing the c-Myc oncogene also overexpress most components of the SUMO pathway and are highly sensitive to SUMOylation inhibition. Targeting the SUMO pathway with recently discovered pharmacological inhibitors, alone or in combination with current therapies, might therefore constitute a powerful strategy to improve the treatment of these cancers.

JMML genomics and decisions

Juvenile myelomonocytic leukemia (JMML) is a unique clonal hematopoietic disorder of early childhood characterized by hyperactivation of the RAS signal transduction pathway. Approximately 90% of patients harbor molecular alteration in 1 of 5 genes (PTPN11, NRAS, KRAS, NF1, CBL), which define genetically and clinically distinct JMML subtypes. Three subtypes, PTPN11- , NRAS-, and KRAS-mutated JMML, are characterized by heterozygous somatic gain-of-function mutations in non syndromic children, while two subtypes, JMML in neurofibromatosis type 1 and in JMML in children with CBL syndrome, are characterized by germ line RAS disease and acquired biallelic inactivation of the respective tumor suppressor genes in hematopoietic cells. In addition to the initiating RAS pathway lesion, secondary genetic alterations within and outside of the RAS pathway are detected in about half the patients. Most recently, genome-wide DNA methylation profiles identified distinct methylation signatures correlating with clinical and genetic features and highly predictive of outcome. JMML is a stem cell disorder, and most JMML patients require allogeneic stem cell transplantation for long-term survival. However, spontaneous disease regression is noted in the majority of children with CBL-mutated JMML and in some NRAS-mutated cases. In the absence of 1 of the 5 canonical RAS pathway alteration, rare mutations in other RAS genes and non-JMML myeloproliferative disorders need to be excluded. Understanding the genetic basis of myeloproliferative disorders in early childhood will greatly improve clinical decision making.

Receptor Tyrosine Kinases: Translocation Partners in Hematopoietic Disorders

Receptor tyrosine kinases (RTKs) activate various signaling pathways and regulate cellular proliferation, survival, migration, and angiogenesis. Malignant neoplasms often circumvent or subjugate these pathways by promoting RTK overactivation through mutation or chromosomal translocation. RTK translocations create a fusion protein containing a dimerizing partner fused to an RTK kinase domain, resulting in constitutive kinase domain activation, altered RTK cellular localization, upregulation of downstream signaling, and novel pathway activation. While RTK translocations in hematological malignancies are relatively rare, clinical evidence suggests that patients with these genetic abnormalities benefit from RTK-targeted inhibitors. Here, we present a timely review of an exciting field by examining RTK chromosomal translocations in hematological cancers, such as Anaplastic Lymphoma Kinase (ALK), Fibroblast Growth Factor Receptor (FGFR), Platelet-Derived Growth Factor Receptor (PDGFR), REarranged during Transfection (RET), Colony Stimulating Factor 1 Receptor (CSF1R), and Neurotrophic Tyrosine Kinase Receptor Type 3 (NTRK3) fusions, and discuss current therapeutic options.

Nucleoporin genes in human diseases

Nuclear pore complexes (NPCs) are large channels spanning the nuclear envelope that mediate nucleocytoplasmic transport. They are composed of multiple copies of ~30 proteins termed nucleoporins (NUPs). Alterations in NUP genes are linked to several human neoplastic and non-neoplastic diseases. This review focuses on NUPs, their genes, localization, function in the NPC and involvement in human diseases.