Targeted therapy in leukemia

Deregulation of New Cell Death Mechanisms in Leukemia

Hematological malignancies are among the top five most frequent forms of cancer in developed countries worldwide. Although the new therapeutic approaches have improved the quality and the life expectancy of patients, the high rate of recurrence and drug resistance are the main issues for counteracting blood disorders. Chemotherapy-resistant leukemic clones activate molecular processes for biological survival, preventing the activation of regulated cell death pathways, leading to cancer progression. In the past decade, leukemia research has predominantly centered around modulating the well-established processes of apoptosis (type I cell death) and autophagy (type II cell death). However, the development of therapy resistance and the adaptive nature of leukemic clones have rendered targeting these cell death pathways ineffective. The identification of novel cell death mechanisms, as categorized by the Nomenclature Committee on Cell Death (NCCD), has provided researchers with new tools to overcome survival mechanisms and activate alternative molecular pathways. This review aims to synthesize information on these recently discovered RCD mechanisms in the major types of leukemia, providing researchers with a comprehensive overview of cell death and its modulation.

Kinase gene fusions in defined subsets of melanoma

Genomic rearrangements resulting in activating kinase fusions have been increasingly described in a number of cancers including malignant melanoma, but their frequency in specific melanoma subtypes has not been reported. We used break-apart fluorescence in situ hybridization (FISH) to identify genomic rearrangements in tissues from 59 patients with various types of malignant melanoma including acral lentiginous, mucosal, superficial spreading, and nodular. We identified four genomic rearrangements involving the genes BRAF, RET, and ROS1. Of these, three were confirmed by Immunohistochemistry (IHC) or sequencing and one was found to be an ARMC10-BRAF fusion that has not been previously reported in melanoma. These fusions occurred in different subtypes of melanoma but all in tumors lacking known driver mutations. Our data suggest gene fusions are more common than previously thought and should be further explored particularly in melanomas lacking known driver mutations.

Emerging targeted therapies for lymphoid malignancies

CONTEXT

Our understanding of molecular events in the pathogenesis of hematologic malignancies has evolved substantially. The research data gathered in the past 3 decades have led to the definition of neoplastic disorders based on specific genetic and molecular alterations, which is reflected in the current World Health Organization's classification of tumors of hematopoietic and lymphoid tissues. Moreover, there have been dramatic successes in the development and implementation of therapies that specifically target the proteins and signaling cascades affected by tumor-specific genetic alterations.

OBJECTIVE

To review the development of select, novel therapies for lymphoid malignancies.

DATA SOURCES

We examine examples from the recent literature in targeting 4 major regulatory pathways: tyrosine kinase activation, transcription factor activity, apoptotic signaling, and histone acetylation in both preclinical models and early-stage (stage 1 and 2) clinical trials.

CONCLUSION

Given the successes of novel compounds that target signaling pathways critical to the growth and survival of lymphoid tumor cells, the routine clinical use of molecularly targeted therapies for the treatment of lymphoid malignancies is likely in the near future.

The immunohistochemistry laboratory: looking at molecules and preparing for tomorrow

CONTEXT

Surgical and subspecialty pathologists rely heavily on the patient's clinical context, imaging studies, morphology, and on ancillary studies such as immunohistochemistry (IHC), cytogenetics, and molecular diagnostics in arriving at accurate, contemporary diagnoses. Lymphoma/leukemia classification has led the way in the number of antibodies used in IHC algorithmic diagnostic approaches to distinguish more than 40 diseases. As the era of genomics, transcriptomics, proteomics, and targeted pathway therapeutics unfolds-and as infusion of federal funds to programs such as Accelerating Clinical Trials of Novel Oncologic PathWays (ACTNOW) requires that correlative biomarker assays be performed in Clinical Laboratory Improvement Amendments of 1988 (CLIA)-certified IHC laboratories-we face changes and challenges for the future.

OBJECTIVE

To discuss the laboratory, pertinent daily diagnostic, prognostic, and therapeutic uses of IHC, and future directions and challenges.

DATA SOURCES

Recent literature review and ongoing current activities in our laboratory and institution.

CONCLUSIONS

Meticulous attention at the microscope by expert subspecialty pathologists using ancillary methods is important in making correct diagnoses. Awareness of the literature and interactions with our research colleagues, including clinical, basic, and translational scientists, continue to expand our insights into and understanding of complex diseases; this will ultimately provide prognostic information to assist in appropriate clinical management of our patients and development of new targeted or combination therapies. Multimodality correlations will continue, with morphology, imaging data, immunophenotyping, and genetics as well as steadily increasing integration of pathway signaling, genome, sequenome, transcriptome, and proteome data used in clinical settings.