Expression of PIM kinases in Reed-Sternberg cells fosters immune privilege and tumor cell survival in Hodgkin lymphoma

A promising natural product in diffuse large B-cell lymphoma therapy by targeting PIM1

Diffuse large B-cell lymphoma (DLBCL) is the most common and aggressive type of B-cell lymphoma. Unfortunately, about one-third of patients either relapse after the initial treatment or are refractory to first-line therapy, indicating a need for new treatment modalities. PIM serine/threonine kinases are proteins that are associated with genetic mutations, overexpression, or translocation events in B-cell lymphomas. We conducted an integrative analysis of whole-exome sequencing in 52 DLBCL patients, and no amplification, mutation, or translocation of the PIM1 gene was detected. Instead, analyses of TCGA and GTEx databases identified that PIM1 expression was increased in DLBCL samples compared to normal tissue, and high expression levels were associated with poor overall survival. Moreover, interference of PIM1 significantly suppressed DLBCL cell proliferation. In addition, we identified anwulignan, a natural small-molecule compound, as a PIM1 inhibitor. Anwulignan directly binds to PIM1 and exerts antitumor effects on DLBCL in vitro and in vivo by inducing apoptosis, cell cycle arrest, and autophagic cell death. Furthermore, we identified an effective synergistic combination between anwulignan and chidamide. Our findings suggested that PIM1 could be a therapeutic target and prognostic factor for DLBCL, and anwulignan holds promise for future development as a natural product for treatment.

A review on structure-function mechanism and signaling pathway of serine/threonine protein PIM kinases as a therapeutic target

The proviral integration for the Moloney murine leukemia virus (PIM) kinases, belonging to serine/threonine kinase family, have been found to be overexpressed in various types of cancers, such as prostate, breast, colon, endometrial, gastric, and pancreatic cancer. The three isoforms PIM kinases i.e., PIM1, PIM2, and PIM3 share a high degree of sequence and structural similarity and phosphorylate substrates controlling tumorigenic phenotypes like proliferation and cell survival. Targeting short-lived PIM kinases presents an intriguing strategy as in vivo knock-down studies result in non-lethal phenotypes, indicating that clinical inhibition of PIM might have fewer adverse effects. The ATP binding site (hinge region) possesses distinctive attributes, which led to the development of novel small molecule scaffolds that target either one or all three PIM isoforms. Machine learning and structure-based approaches have been at the forefront of developing novel and effective chemical therapeutics against PIM in preclinical and clinical settings, and none have yet received approval for cancer treatment. The stability of PIM isoforms is maintained by PIM kinase activity, which leads to resistance against PIM inhibitors and chemotherapy; thus, to overcome such effects, PIM proteolysis targeting chimeras (PROTACs) are now being developed that specifically degrade PIM proteins. In this review, we recapitulate an overview of the oncogenic functions of PIM kinases, their structure, function, and crucial signaling network in different types of cancer, and the potential of pharmacological small-molecule inhibitors. Further, our comprehensive review also provides valuable insights for developing novel antitumor drugs that specifically target PIM kinases in the future. In conclusion, we provide insights into the benefits of degrading PIM kinases as opposed to blocking their catalytic activity to address the oncogenic potential of PIM kinases.

PIM kinases regulate early human Th17 cell differentiation

The serine/threonine-specific Moloney murine leukemia virus (PIM) kinase family (i.e., PIM1, PIM2, and PIM3) has been extensively studied in tumorigenesis. PIM kinases are downstream of several cytokine signaling pathways that drive immune-mediated diseases. Uncontrolled T helper 17 (Th17) cell activation has been associated with the pathogenesis of autoimmunity. However, the detailed molecular function of PIMs in human Th17 cell regulation has yet to be studied. In the present study, we comprehensively investigated how the three PIMs simultaneously alter transcriptional gene regulation during early human Th17 cell differentiation. By combining PIM triple knockdown with bulk and scRNA-seq approaches, we found that PIM deficiency promotes the early expression of key Th17-related genes while suppressing Th1-lineage genes. Further, PIMs modulate Th cell signaling, potentially via STAT1 and STAT3. Overall, our study highlights the inhibitory role of PIMs in human Th17 cell differentiation, thereby suggesting their association with autoimmune phenotypes.

Ultra-Deep Sequencing Reveals the Mutational Landscape of Classical Hodgkin Lymphoma

The malignant Hodgkin and Reed Sternberg (HRS) cells of classical Hodgkin lymphoma (cHL) are scarce in affected lymph nodes, creating a challenge to detect driver somatic mutations. As an alternative to cell purification techniques, we hypothesized that ultra-deep exome sequencing would allow genomic study of HRS cells, thereby streamlining analysis and avoiding technical pitfalls. To test this, 31 cHL tumor/normal pairs were exome sequenced to approximately 1,000× median depth of coverage. An orthogonal error-corrected sequencing approach verified >95% of the discovered mutations. We identified mutations in genes novel to cHL including: CDH5 and PCDH7, novel stop gain mutations in IL4R, and a novel pattern of recurrent mutations in pathways regulating Hippo signaling. As a further application of our exome sequencing, we attempted to identify expressed somatic single-nucleotide variants (SNV) in single-nuclei RNA sequencing (snRNA-seq) data generated from a patient in our cohort. Our snRNA analysis identified a clear cluster of cells containing a somatic SNV identified in our deep exome data. This cluster has differentially expressed genes that are consistent with genes known to be dysregulated in HRS cells (e.g., PIM1 and PIM3). The cluster also contains cells with an expanded B-cell clonotype further supporting a malignant phenotype. This study provides proof-of-principle that ultra-deep exome sequencing can be utilized to identify recurrent mutations in HRS cells and demonstrates the feasibility of snRNA-seq in the context of cHL. These studies provide the foundation for the further analysis of genomic variants in large cohorts of patients with cHL.

SIGNIFICANCE

Our data demonstrate the utility of ultra-deep exome sequencing in uncovering somatic variants in Hodgkin lymphoma, creating new opportunities to define the genes that are recurrently mutated in this disease. We also show for the first time the successful application of snRNA-seq in Hodgkin lymphoma and describe the expression profile of a putative cluster of HRS cells in a single patient.

SIRT1 and HSP90α feed-forward circuit safeguards chromosome segregation integrity in diffuse large B cell lymphomas

Diffuse large B-cell lymphoma (DLBCL) is the most common aggressive non-Hodgkin lymphoma in adults, exhibiting highly heterogenous clinical behavior and complex molecular background. In addition to the genetic complexity, different DLBCL subsets exhibit phenotypic features independent of the genetic background. For example, a subset of DLBCLs is distinguished by increased oxidative phosphorylation and unique transcriptional features, including overexpression of certain mitochondrial genes and a molecular chaperone, heat shock protein HSP90α (termed "OxPhos" DLBCLs). In this study, we identified a feed-forward pathogenetic circuit linking HSP90α and SIRT1 in OxPhos DLBCLs. The expression of the inducible HSP90α isoform remains under SIRT1-mediated regulation. SIRT1 knockdown or chemical inhibition reduced HSP90α expression in a mechanism involving HSF1 transcription factor, whereas HSP90 inhibition reduced SIRT1 protein stability, indicating that HSP90 chaperones SIRT1. SIRT1-HSP90α interaction in DLBCL cells was confirmed by co-immunoprecipitation and proximity ligation assay (PLA). The number of SIRT1-HSP90α complexes in PLA was significantly higher in OxPhos- dependent than -independent cells. Importantly, SIRT1-HSP90α interactions in OxPhos DLBCLs markedly increased in mitosis, suggesting a specific role of the complex during this cell cycle phase. RNAi-mediated and chemical inhibition of SIRT1 and/or HSP90 significantly increased the number of cells with chromosome segregation errors (multipolar spindle formation, anaphase bridges and lagging chromosomes). Finally, chemical SIRT1 inhibitors induced dose-dependent cytotoxicity in OxPhos-dependent DLBCL cell lines and synergized with the HSP90 inhibitor. Taken together, our findings define a new OxPhos-DLBCL-specific pathogenetic loop involving SIRT1 and HSP90α that regulates chromosome dynamics during mitosis and may be exploited therapeutically.

Discovery of PIM-1 kinase inhibitors based on the 2,5-disubstituted 1,3,4-oxadiazole scaffold against prostate cancer: Design, synthesis, in vitro and in vivo cytotoxicity investigation

PIM-1 kinases play an established role in prostate cancer development and progression. This research work tackles the design and synthesis of new PIM-1 kinase targeting 2,5-disubstituted-1,3,4-oxadiazoles 10a-g&11a-f, and investigation thereof as potential anti-cancer agents through in vitro cytotoxicity assay followed by in vivo studies along with exploration of this chemotype's plausible mechanism of action. In vitro cytotoxicity experiments have disclosed 10f as the most potent derivative against PC-3 cells (IC₅₀ = 16 nM) compared to the reference drug Staurosporine (IC₅₀ = 0.36 μM), also eliciting good cytotoxicity against HepG2 and MCF-7 cells (IC₅₀ = 0.13 and 5.37 μM, respectively). Investigating PIM-1 kinase inhibitory activity of compound 10f revealed an IC₅₀ of 17 nM paralleled to that of Staurosporine (IC₅₀ = 16.7 nM). Furthermore, compound 10f displayed an antioxidant activity eliciting a DPPH inhibition ratio of 94% as compared to Trolox (96%). Further investigation demonstrated that 10f induced apoptosis in treated PC-3 cells by 43.2-fold (19.44%) compared to 0.45% in control. 10f also disrupted the PC-3 cell cycle by increasing the cell population at the PreG1-phase by 19.29-fold while decreasing the G2/M-phase by 0.56-fold compared to control. Moreover, 10f affected a downregulation of JAK2, STAT3 and Bcl-2 and upregulation of caspases 3, 8 and 9 levels that activated the caspase-dependent apoptosis. Finally, in vivo 10f-treatment caused a significant increase in tumor inhibition by 64.2% compared to 44.5% in Staurosporine treatment of the PC-3 xenograft mouse model. Additionally, it improved the hematological, biochemical parameters, and histopathological examinations compared to control untreated animals. Finally, docking of 10f with the ATP-binding site of PIM-1 kinase demonstrated good recognition of and effective binding to the active site. In conclusion, compound 10f represents a promising lead compound that merits further future optimization for controlling prostate cancer.

Intravascular Large B-Cell Lymphoma Genomic Profile Is Characterized by Alterations in Genes Regulating NF-κB and Immune Checkpoints

Intravascular large B-cell lymphoma (IVLBCL) is an uncommon lymphoma with an aggressive clinical course characterized by selective growth of tumor cells within the vessels. Its pathogenesis is still uncertain and there is little information on the underlying genomic alterations. In this study, we performed a clinicopathologic and next-generation sequencing analysis of 15 cases of IVLBCL using a custom panel for the detection of alterations in 68 recurrently mutated genes in B-cell lymphomagenesis. Six patients had evidence of hemophagocytic syndrome. Four patients presented concomitantly a solid malignancy. Tumor cells outside the vessels were observed in 7 cases, 2 with an overt diffuse large B-cell cell lymphoma. In 4 samples, tumor cells infiltrated lymphatic vessel in addition to blood capillaries. Programmed death-ligand 1 (PD-L1) was positive in tumor cells in 4 of 11 evaluable samples and in macrophages intermingled with tumor cells in 8. PD-L1 copy number gains were identified in a higher proportion of cases expressing PD-L1 than in negative tumors. The most frequently mutated gene was PIM1 (9/15, 60%), followed by MYD88L265P and CD79B (8/15, 53% each). In 6 cases, MYD88L265P and CD79B mutations were detected concomitantly. We also identified recurrent mutations in IRF4 , TMEM30A , BTG2 , and ETV6 loci (4/15, 27% each) and novel driver mutations in NOTCH2 , CCND3 , and GNA13 , and an IRF4 translocation in 1 case each. The mutational profile was similar in patients with and without evidence of hemophagocytic syndrome and in cases with or without dissemination of tumor cells outside the vessels. Our results confirm the relevance of mutations in B-cell receptor/nuclear factor-κB signaling and immune escape pathways in IVLBCL and identify novel driver alterations. The similar mutational profile in tumors with extravascular dissemination suggests that these cases may also be considered in the spectrum of IVLBCL.

Profile of MicroRNAs Associated with Death Due to Disease Progression in Metastatic Papillary Thyroid Carcinoma Patients

Papillary thyroid carcinoma (PTC) is the most common neoplasm of the endocrine system and has an excellent long-term prognosis, with low rates of distant metastatic disease. Although infrequent, there are cases of deaths directly related to PTC, especially in patients with metastatic disease, and the factors that could be associated with this unfavorable outcome remain a major challenge in clinical practice. Recently, research into genetic factors associated with PTC has gained ground, especially mutations in the TERT promoter and BRAF gene. However, the role of microRNAs remains poorly studied, especially in those patients who have an unfavorable outcome at follow-up. This paper aims to evaluate molecular markers related to the different pathological processes of PTC, as well as the histological characteristics of the neoplasm, and to compare this profile with prognosis and death from the disease using an analysis of patients treated for metastatic disease in a single tertiary cancer center. Evaluation of microRNA expression in paraffin-embedded tumor specimens was carried out by quantitative PCR using the TaqMan® Low Density Array (TLDA) system. Metastatic patients who died from progression of PTC had higher expressions of miR-101-3p, miR-17-5p, and miR-191-5p when compared to patients with stable metastatic disease. These findings are of great importance but should be considered as preliminary because of the small sample.

Targeting Pim kinases in hematological cancers: molecular and clinical review

Decades of research has recognized a solid role for Pim kinases in lymphoproliferative disorders. Often up-regulated following JAK/STAT and tyrosine kinase receptor signaling, Pim kinases regulate cell proliferation, survival, metabolism, cellular trafficking and signaling. Targeting Pim kinases represents an interesting approach since knock-down of Pim kinases leads to non-fatal phenotypes in vivo suggesting clinical inhibition of Pim may have less side effects. In addition, the ATP binding site offers unique characteristics that can be used for the development of small inhibitors targeting one or all Pim isoforms. This review takes a closer look at Pim kinase expression and involvement in hematopoietic cancers. Current and past clinical trials and in vitro characterization of Pim kinase inhibitors are examined and future directions are discussed. Current studies suggest that Pim kinase inhibition may be most valuable when accompanied by multi-drug targeting therapy.

Targeting PIM Kinases to Improve the Efficacy of Immunotherapy

The Proviral Integration site for Moloney murine leukemia virus (PIM) kinases is a family of serine/threonine kinases that regulates numerous signaling networks that promote cell growth, proliferation, and survival. PIM kinases are commonly upregulated in both solid tumors and hematological malignancies. Recent studies have demonstrated that PIM facilitates immune evasion in cancer by promoting an immunosuppressive tumor microenvironment that suppresses the innate anti-tumor response. The role of PIM in immune evasion has sparked interest in examining the effect of PIM inhibition in combination with immunotherapy. This review focuses on the role of PIM kinases in regulating immune cell populations, how PIM modulates the immune tumor microenvironment to promote immune evasion, and how PIM inhibitors may be used to enhance the efficacy of immunotherapy.

Nicotinonitrile-derived apoptotic inducers: Design, synthesis, X-ray crystal structure and Pim kinase inhibition

Although a plethora of targeted anticancer small molecule drugs became available, the low response rate and drug resistance imply the continuous need for expanding the anticancer chemical space. In this study, a novel series of nicotinonitrile derivatives was designed, synthesized and evaluated for cytotoxic activities in HepG2 and MCF-7 cells. All derivatives showed high to moderate cytotoxic activity against both cell lines, with cell-type and chemotype-dependent cytotoxic potential. The normal HEK-293 T cells were ca. 50-fold less susceptible to the cytotoxic effect of the inhibitors. The in vitro enzyme inhibitory activity of selected active cytotoxic derivatives 8c, 8e, 9a, 9e and 12 showed that they have sub- to one digit micromolar 50 % inhibitory concentration (IC₅₀) against the three Pim kinase isoforms, with 8e being the most potent (IC₅₀ ≤ 0.28 μM against three Pim kinases), comparable to the pan kinase inhibitor, Staurosporine. In HepG2, 8e induced cell cycle arrest at the G2/M phase. Apoptotic mechanistic studies with 8c and 8e in HepG2 cells, indicated a significant upregulation in both P53 and caspase-3 relative gene expression, as well as increased Bax/Bcl-2 protein expression level. Further, docking studies combined with molecular dynamic simulation showed a stable complex with high binding affinity of 8e to Pim-1 kinase; exploiting a negative electrostatic potential surface interaction with the added dimethyl amino group in the new compounds. Moreover, in silico ADME profile prediction indicated that all compounds are orally bioavailable and most of them can penetrate the blood-brain barrier. This study presents novel nicotinonitrile derivatives as auspicious hits for further optimization as antiproliferative agents against liver cancer cells and promising pan Pim kinase inhibitors at submicromolar concentrations.

NFkB Pathway and Hodgkin Lymphoma

The tumor cells that drive classical Hodgkin lymphoma (cHL), namely, Hodgkin and Reed-Sternberg (HRS) cells, display hallmark features that include their rareness in contrast with an extensive and rich reactive microenvironment, their loss of B-cell phenotype markers, their immune escape capacity, and the activation of several key biological pathways, including the constitutive activation of the NFkB pathway. Both canonical and alternative pathways are deregulated by genetic alterations of their components or regulators, EBV infection and interaction with the microenvironment through multiple receptors, including CD30, CD40, BAFF, RANK and BCMA. Therefore, NFkB target genes are involved in apoptosis, cell proliferation, JAK/STAT pathway activation, B-cell marker expression loss, cellular interaction and a positive NFkB feedback loop. Targeting this complex pathway directly (NIK inhibitors) or indirectly (PIM, BTK or NOTCH) remains a challenge with potential therapeutic relevance. Nodular predominant HL (NLPHL), a distinct and rare HL subtype, shows a strong NFkB activity signature because of mechanisms that differ from those observed in cHL, which is discussed in this review.

Updates in the Role of Checkpoint Inhibitor Immunotherapy in Classical Hodgkin's Lymphoma

Classical Hodgkin's lymphoma is a highly curable disease, but 10-25% of patients with higher-risk disease relapse. The introduction of checkpoint inhibitors (CPIs) targeting PD-1 have changed the landscape of treatment for patients with relapsed/refractory disease to multiple lines of therapy. The depth of response to CPI as a monotherapy is highest in the first relapse as salvage therapy based on outcomes reported in several phase II studies. With earlier use of CPI and brentuximab vedotin, the optimal sequencing of therapy is evolving. In this review, we will summarize clinical investigation of anti-PD-1 mAb in earlier line settings to provide insights on utilizing these agents as chemotherapy- and radiation-sparing approaches, increasing depth of response, and as part of combination regimens.

Stabilization of PIM Kinases in Hypoxia Is Mediated by the Deubiquitinase USP28

Proviral integration sites for Moloney murine leukemia virus (PIM) kinases are upregulated at the protein level in response to hypoxia and have multiple protumorigenic functions, promoting cell growth, survival, and angiogenesis. However, the mechanism responsible for the induction of PIM in hypoxia remains unknown. Here, we examined factors affecting PIM kinase stability in normoxia and hypoxia. We found that PIM kinases were upregulated in hypoxia at the protein level but not at the mRNA level, confirming that PIMs were upregulated in hypoxia in a hypoxia inducible factor 1-independent manner. PIM kinases were less ubiquitinated in hypoxia than in normoxia, indicating that hypoxia reduced their proteasomal degradation. We identified the deubiquitinase ubiquitin-specific protease 28 (USP28) as a key regulator of PIM1 and PIM2 stability. The overexpression of USP28 increased PIM protein stability and total levels in both normoxia and hypoxia, and USP28-knockdown significantly increased the ubiquitination of PIM1 and PIM2. Interestingly, coimmunoprecipitation assays showed an increased interaction between PIM1/2 and USP28 in response to hypoxia, which correlated with reduced ubiquitination and increased protein stability. In a xenograft model, USP28-knockdown tumors grew more slowly than control tumors and showed significantly lower levels of PIM1 in vivo. In conclusion, USP28 blocked the ubiquitination and increased the stability of PIM1/2, particularly in hypoxia. These data provide the first insight into proteins responsible for controlling PIM protein degradation and identify USP28 as an important upstream regulator of this hypoxia-induced, protumorigenic signaling pathway.

Janus Kinase Signaling: Oncogenic Criminal of Lymphoid Cancers

Simple Summary

Janus kinases (JAKs) are transmembrane receptors that pass signals from extracellular ligands to downstream. Increasing evidence has suggested that JAK family aberrations promote lymphoid cancer pathogenesis and progression through mediating gene expression via the JAK/STAT pathway or noncanonical JAK signaling. We are here to review how canonical JAK/STAT and noncanonical JAK signalings are represented and deregulated in lymphoid malignancies and how to target JAK for therapeutic purposes.

Abstract

The Janus kinase (JAK) family are known to respond to extracellular cytokine stimuli and to phosphorylate and activate signal transducers and activators of transcription (STAT), thereby modulating gene expression profiles. Recent studies have highlighted JAK abnormality in inducing over-activation of the JAK/STAT pathway, and that the cytoplasmic JAK tyrosine kinases may also have a nuclear role. A couple of anti-JAK therapeutics have been developed, which effectively harness lymphoid cancer cells. Here we discuss mutations and fusions leading to JAK deregulations, how upstream nodes drive JAK expression, how classical JAK/STAT pathways are represented in lymphoid malignancies and the noncanonical and nuclear role of JAKs. We also summarize JAK inhibition therapeutics applied alone or synergized with other drugs in treating lymphoid malignancies.

Inhibition of PIM Kinases in DLBCL Targets MYC Transcriptional Program and Augments the Efficacy of Anti-CD20 Antibodies

The family of PIM serine/threonine kinases includes three highly conserved oncogenes, PIM1, PIM2, and PIM3, which regulate multiple pro-survival pathways and cooperate with other oncogenes such as MYC. Recent genomic CRISPR-Cas9 screens further highlighted oncogenic functions of PIMs in diffuse large B cell lymphoma (DLBCL) cells, justifying development of small molecule PIM inhibitors and therapeutic targeting of PIM kinases in lymphomas. However, detailed consequences of PIM inhibition in DLBCL remain undefined. Using chemical and genetic PIM blockade, we comprehensively characterized PIM kinase-associated pro-survival functions in DLBCL and the mechanisms of PIM inhibition-induced toxicity. Treatment of DLBCL cells with SEL24/MEN1703, a pan PIM inhibitor in clinical development, decreased BAD phosphorylation and cap-dependent protein translation, reduced MCL1 expression, and induced apoptosis. PIM kinases were tightly coexpressed with MYC in diagnostic DLBCL biopsies, and PIM inhibition in cell lines and patient-derived primary lymphoma cells decreased MYC levels as well as expression of multiple MYC-dependent genes, including PLK1. Chemical and genetic PIM inhibition upregulated surface CD20 levels in a MYC-dependent fashion. Consistently, MEN1703 and other clinically available pan-PIM inhibitors synergized with the anti-CD20 monoclonal antibody rituximab in vitro, increasing complement-dependent cytotoxicity and antibody-mediated phagocytosis. Combined treatment with PIM inhibitor and rituximab suppressed tumor growth in lymphoma xenografts more efficiently than either drug alone. Taken together, these results show that targeting PIM in DLBCL exhibits pleiotropic effects that combine direct cytotoxicity with potentiated susceptibility to anti-CD20 antibodies, justifying further clinical development of such combinatorial strategies.

Therapeutic targeting of PIM KINASE signaling in cancer therapy: Structural and clinical prospects

BACKGROUND

PIM kinases are well-studied drug targets for cancer, belonging to Serine/Threonine kinases family. They are the downstream target of various signaling pathways, and their up/down-regulation affects various physiological processes. PIM family comprises three isoforms, namely, PIM-1, PIM-2, and PIM-3, on alternative initiation of translation and they have different levels of expression in different types of cancers. Its structure shows a unique ATP-binding site in the hinge region which makes it unique among other kinases.

SCOPE OF REVIEW

PIM kinases are widely reported in hematological malignancies along with prostate and breast cancers. Currently, many drugs are used as inhibitors of PIM kinases. In this review, we highlighted the physiological significance of PIM kinases in the context of disease progression and therapeutic targeting. We comprehensively reviewed the PIM kinases in terms of their expression and regulation of different physiological roles. We further predicted functional partners of PIM kinases to elucidate their role in the cellular physiology of different cancer and mapped their interaction network.

MAJOR CONCLUSIONS

A deeper mechanistic insight into the PIM signaling involved in regulating different cellular processes, including transcription, apoptosis, cell cycle regulation, cell proliferation, cell migration and senescence, is provided. Furthermore, structural features of PIM have been dissected to understand the mechanism of inhibition and subsequent implication of designed inhibitors towards therapeutic management of prostate, breast and other cancers.

GENERAL SIGNIFICANCE

Being a potential drug target for cancer therapy, available drugs and PIM inhibitors at different stages of clinical trials are discussed in detail.

Novel Pan-Pim Kinase Inhibitors With Imidazopyridazine and Thiazolidinedione Structure Exert Potent Antitumor Activities

Pim kinases are overexpressed in various types of hematological malignancies and solid carcinomas, and promote cell proliferation and survival. Here in this study, we investigated the preclinical profile of novel pan-Pim kinase inhibitors with imidazopyridazine and thiazolidinedione structure. Imidazopyridazine-thiazolidinediones inhibited activities of Pim kinases with IC₅₀ values of tens to hundreds nanomolar. With YPC-21440 and/or YPC-21817, which exhibited especially high inhibitory activities against Pim kinases, we investigated in vitro and in vivo activities of imidazopyridazine-thiazolidinediones. In silico analysis of binding mode of YPC-21440 and Pim kinases revealed that it directly bound to ATP-binding pockets of Pim kinases. In the kinase panel tested, YPC-21440 and YPC-21817 were highly specific to Pim kinases. These compounds exerted antiproliferative activities against various cancer cell lines derived from hematological malignancies and solid carcinomas. Furthermore, they suppressed phosphorylation of Pim kinase substrates, arrested cell cycle at the G1 phase, and induced apoptosis in cultured cancer cells. In tumor xenograft models, YPC-21440 methanesulfonate and YPC-21817 methanesulfonate exerted antitumor activities. Furthermore, pharmacodynamic analysis with a xenograft model suggested that YPC-21817 methanesulfonate inhibited Pim kinases in tumors. In conclusion, our data revealed that imidazopyridazine-thiazolidinediones are novel Pim kinases inhibitors, effective on various types of cancer cell lines both in vitro and in vivo.

Design and synthesis of a novel mitochondria-targeted osteosarcoma theranostic agent based on a PIM1 kinase inhibitor

Osteosarcoma (OS) is the most common malignancy of the skeletal system, with a poor prognosis and high rate of recurrence. Adequate surgical margin and adjuvant chemotherapy improve the overall survival and limb salvage rate of osteosarcoma patients. Previous studies have showed that OS exhibits an increase in the expression of proviral integration site for Moloney murine leukemia virus 1 (PIM1) kinase, and high levels of PIM1 are also associated with poor OS prognosis and metastasis. We exploited the overexpression of proto-oncogenic PIM1 in OS towards the development of a novel near-infrared imaging and targeted therapeutic agent, namely QCAi-Cy7d by conjugating a PIM1 small molecule inhibitor and heptamethine cyanine dye, for simultaneous guiding surgery and chemotherapy. QCAi-Cy7d showed targeted imaging and anticancer activities against OS in vitro and vivo without any obvious toxicity, and its antitumoral activity was much greater than the parent PIMI inhibitor. These results demonstrated the potential of new conjugate of PIM1 inhibitor and near-infrared imaging, supporting structure-based design and development of theranostic agents for precise tumor imaging and targeted treatment.

Targeting PIM Kinases to Overcome Therapeutic Resistance in Cancer

Cancer progression and the onset of therapeutic resistance are often the results of uncontrolled activation of survival kinases. The proviral integration for the Moloney murine leukemia virus (PIM) kinases are oncogenic serine/threonine kinases that regulate tumorigenesis by phosphorylating a wide range of substrates that control cellular metabolism, proliferation, and survival. Because of their broad impact on cellular processes that facilitate progression and metastasis in many cancer types, it has become clear that the activation of PIM kinases is a significant driver of resistance to various types of anticancer therapies. As a result, efforts to target PIM kinases for anticancer therapy have intensified in recent years. Clinical and preclinical studies indicate that pharmacologic inhibition of PIM has the potential to significantly improve the efficacy of standard and targeted therapies. This review focuses on the signaling pathways through which PIM kinases promote cancer progression and resistance to therapy, as well as highlights biological contexts and promising strategies to exploit PIM as a therapeutic target in cancer.

PIM Kinases Promote Survival and Immune Escape in Primary Mediastinal Large B-Cell Lymphoma through Modulation of JAK-STAT and NF-κB Activity

Primary mediastinal large B-cell lymphoma (PMBL) cells depend on the constitutive activity of NF-κB and STAT transcription factors, which drive expression of multiple molecules essential for their survival. In a molecularly related B-cell malignant tumor (classic Hodgkin lymphoma), tumor Reed-Sternberg cells overexpress oncogenic (proviral integration site for Moloney murine leukemia virus (PIM) 1, 2, and 3 kinases in a NF-κB- and STAT-dependent manner and PIMs enhance survival and expression of immunomodulatory molecules. Given the multiple overlapping characteristics of Reed-Sternberg and PMBL cells, we hypothesized that PIM kinases may be overexpressed in PMBL and involved in PMBL pathogenesis. The expression of PIM kinases in PMBL diagnostic biopsy specimens was assessed and their role in survival and immune escape of the tumor cells was determined. PIMs were abundantly expressed in primary tumors and PMBL cell lines. Inhibition of PIM kinases was toxic to PMBL cells, attenuated protein translation, and down-regulated NF-κB- and STAT-dependent transcription of prosurvival factors BCL2A1, BCL2L1, and FCER2. Furthermore, PIM inhibition decreased expression of molecules engaged in shaping the immunosuppressive microenvironment, including programmed death ligand 1/2 and chemokine (C-C motif) ligand 17. Taken together, our data indicate that PIMs support PMBL cell survival and immune escape and identify PIMs as promising therapeutic targets for PMBL.

BRAF inhibition curtails IFN-gamma-inducible PD-L1 expression and upregulates the immunoregulatory protein galectin-1 in melanoma cells

Although melanoma is considered one of the most immunogenic malignancies, spontaneous T‐cell responses to melanoma antigens are ineffective due to tumor cell‐intrinsic or microenvironment‐driven immune evasion mechanisms. For example, oncogenic BRAF V600E mutation in melanoma cells fosters tumor immune escape by modulating cell immunogenicity and microenvironment composition. BRAF inhibition has been shown to increase melanoma cell immunogenicity, but these effects are transient and long‐term responses are uncommon. For these reasons, we aimed to further characterize the role of BRAF‐V600E mutation in the modulation of PD‐L1, a known immunoregulatory molecule, and galectin‐1 (Gal‐1), a potent immunoregulatory lectin involved in melanoma immune privilege. We report herein that vemurafenib downregulates IFN‐γ‐induced PD‐L1 expression by interfering with STAT1 activity and by decreasing PD‐L1 protein translation. Surprisingly, melanoma cells exposed to vemurafenib expressed higher levels of Gal‐1. In coculture experiments, A375 melanoma cells pretreated with vemurafenib induced apoptosis of interacting Jurkat T cells, whereas genetic inhibition of Gal‐1 in these cells restored the viability of cocultured T lymphocytes, indicating that Gal‐1 contributes to tumor immune escape. Importantly, Gal‐1 plasma concentration increased in patients progressing on BRAF/MEK inhibitor treatment, but remained stable in responding patients. Taken together, these results suggest a two‐faceted nature of BRAF inhibition‐associated immunomodulatory effects: an early immunostimulatory activity, mediated at least in part by decreased PD‐L1 expression, and a delayed immunosuppressive effect associated with Gal‐1 induction. Importantly, our observations suggest that Gal‐1 might be utilized as a potential biomarker and a putative therapeutic target in melanoma patients.

Proto-Oncogene Serine/Threonine Kinase PIM3 Promotes Cell Migration via Modulating Rho GTPase Signaling

The proto-oncogene serine/threonine-protein kinase PIM3 plays critical roles in cancer, and it has been extensively exploited as a drug target. Here, we investigated the quantitative changes in the cellular proteome and phosphoproteome in liver cancer cells overexpressing PIM3 to obtain a better understanding of the regulatory functions of PIM3 and the underlying molecular mechanisms. This work depicted the landscape of gene expression and protein phosphorylation potentially regulated by PIM3. A signaling network analysis showed that PIM3 may coordinate various cellular processes, for example, signal transduction, cell cycle, apoptosis, and so forth. Intriguingly, quantitative phosphoproteomics revealed that the PIM3 overexpression elevated the phosphorylation of multiple Rho GTPase modulators that target RhoA, a central modulator of cell movement. Further investigations confirmed that PIM3 activated RhoA to subsequently regulate cytoskeletal rearrangements and cell migration. Taken together, this study comprehensively mapped the proteome and phosphoproteome regulated by PIM3 and revealed its role in promoting liver cancer cell migration and invasion by modulating Rho GTPase signaling.

PIM kinase inhibition: co-targeted therapeutic approaches in prostate cancer

PIM kinases have been shown to play a role in prostate cancer development and progression, as well as in some of the hallmarks of cancer, especially proliferation and apoptosis. Their upregulation in prostate cancer has been correlated with decreased patient overall survival and therapy resistance. Initial efforts to inhibit PIM with monotherapies have been hampered by compensatory upregulation of other pathways and drug toxicity, and as such, it has been suggested that co-targeting PIM with other treatment approaches may permit lower doses and be a more viable option in the clinic. Here, we present the rationale and basis for co-targeting PIM with inhibitors of PI3K/mTOR/AKT, JAK/STAT, MYC, stemness, and RNA Polymerase I transcription, along with other therapies, including androgen deprivation, radiotherapy, chemotherapy, and immunotherapy. Such combined approaches could potentially be used as neoadjuvant therapies, limiting the development of resistance to treatments or sensitizing cells to other therapeutics. To determine which drugs should be combined with PIM inhibitors for each patient, it will be key to develop companion diagnostics that predict response to each co-targeted option, hopefully providing a personalized medicine pathway for subsets of prostate cancer patients in the future.

Human papillomavirus insertions identify the PIM family of serine/threonine kinases as targetable driver genes in head and neck squamous cell carcinoma

Human papillomavirus (HPV) insertions in cancer genomes have been linked to various forms of focal genomic instability and altered expression of neighboring genes. Here we tested the hypothesis that investigation of HPV insertions in a head and neck cancer squamous cell carcinoma (HNSCC) cell line would identify targetable driver genes contributing to oncogenesis of other HNSCC. In the cell line UPCI:SCC090 HPV16 integration amplified the PIM1 serine/threonine kinase gene ~16-fold, thereby increasing transcript and protein levels. We used genetic and pharmacological approaches to inhibit PIM kinases in this and other HNSCC cell lines. Knockdown of PIM1 transcripts by transfected short hairpin RNAs reduced UPCI:SCC090 viability. CRISPR/Cas9-mediated mutagenesis of PIM1 caused cell cycle arrest and apoptosis. Pharmacological inhibition of PIM family kinases decreased growth of UPCI:SCC090 and additional HNSCC cell lines in vitro and a xenograft UPCI:SCC090 model in vivo. Based on established interactions between intracellular signaling pathways and relatively high levels of gene expression in almost all HNSCC, we also evaluated combinations of PIM kinase and epidermal growth factor receptor (EGFR) inhibitors. Dual inhibition of these pathways resulted in supra-additive cell death. These data support clinical testing of PIM inhibitors alone or in combination in HNSCC.

Current perspectives on targeting PIM kinases to overcome mechanisms of drug resistance and immune evasion in cancer

PIM kinases are a class of serine/threonine kinases that play a role in several of the hallmarks of cancer including cell cycle progression, metabolism, inflammation and immune evasion. Their constitutively active nature and unique catalytic structure has led them to be an attractive anticancer target through the use of small molecule inhibitors. This review highlights the enhanced activity of PIM kinases in cancer that can be driven by hypoxia in the tumour microenvironment and the important role that aberrant PIM kinase activity plays in resistance mechanisms to chemotherapy, radiotherapy, anti-angiogenic therapies and targeted therapies. We highlight an interaction of PIM kinases with numerous major oncogenic players, including but not limited to, stabilisation of p53, synergism with c-Myc, and notable parallel signalling with PI3K/Akt. We provide a comprehensive overview of PIM kinase's role as an escape mechanism to targeted therapies including PI3K/mTOR inhibitors, MET inhibitors, anti-HER2/EGFR treatments and the immunosuppressant rapamycin, providing a rationale for co-targeting treatment strategies for a more durable patient response. The current status of PIM kinase inhibitors and their use as a combination therapy with other targeted agents, in addition to the development of novel multi-molecularly targeted single therapeutic agents containing a PIM kinase targeting moiety are discussed.

Phosphorylation of HSF1 by PIM2 Induces PD-L1 Expression and Promotes Tumor Growth in Breast Cancer

Heat shock transcription factor 1 (HSF1) is the master regulator of the proteotoxic stress response, which plays a key role in breast cancer tumorigenesis. However, the mechanisms underlying regulation of HSF1 protein stability are still unclear. Here, we show that HSF1 protein stability is regulated by PIM2-mediated phosphorylation of HSF1 at Thr120, which disrupts the binding of HSF1 to the E3 ubiquitin ligase FBXW7. In addition, HSF1 Thr120 phosphorylation promoted proteostasis and carboplatin-induced autophagy. Interestingly, HSF1 Thr120 phosphorylation induced HSF1 binding to the PD-L1 promoter and enhanced PD-L1 expression. Furthermore, HSF1 Thr120 phosphorylation promoted breast cancer tumorigenesis in vitro and in vivo. PIM2, pThr120-HSF1, and PD-L1 expression positively correlated with each other in breast cancer tissues. Collectively, these findings identify PIM2-mediated HSF1 phosphorylation at Thr120 as an essential mechanism that regulates breast tumor growth and potential therapeutic target for breast cancer. SIGNIFICANCE: These findings identify heat shock transcription factor 1 as a new substrate for PIM2 kinase and establish its role in breast tumor progression.

HCV and flaviviruses hijack cellular mechanisms for nuclear STAT2 degradation: Up-regulation of PDLIM2 suppresses the innate immune response

Host encounters with viruses lead to an innate immune response that must be rapid and broadly targeted but also tightly regulated to avoid the detrimental effects of unregulated interferon expression. Viral stimulation of host negative regulatory mechanisms is an alternate method of suppressing the host innate immune response. We examined three key mediators of the innate immune response: NF-KB, STAT1 and STAT2 during HCV infection in order to investigate the paradoxical induction of an innate immune response by HCV despite a multitude of mechanisms combating the host response. During infection, we find that all three are repressed only in HCV infected cells but not in uninfected bystander cells, both in vivo in chimeric mouse livers and in cultured Huh7.5 cells after IFNα treatment. We show here that HCV and Flaviviruses suppress the innate immune response by upregulation of PDLIM2, independent of the host interferon response. We show PDLIM2 is an E3 ubiquitin ligase that also acts to stimulate nuclear degradation of STAT2. Interferon dependent relocalization of STAT1/2 to the nucleus leads to PDLIM2 ubiquitination of STAT2 but not STAT1 and the proteasome-dependent degradation of STAT2, predominantly within the nucleus. CRISPR/Cas9 knockout of PDLIM2 results in increased levels of STAT2 following IFNα treatment, retention of STAT2 within the nucleus of HCV infected cells after IFNα stimulation, increased interferon response, and increased resistance to infection by several flaviviruses, indicating that PDLIM2 is a global regulator of the interferon response.

The response of cells to an invading pathogen must be swift and well controlled because of the detrimental effects of chronic inflammation. However, viruses often hijack host control mechanisms. HCV and flaviviruses are known to suppress the innate immune response in cells by a variety of mechanisms. This study clarifies and expands a specific cellular mechanism for global control of the antiviral response after the induction of interferon expression. It shows how several viruses hijack this control mechanism to suppress the innate interferon response.

The role of dorsal root ganglia PIM1 in peripheral nerve injury-induced neuropathic pain

Neuropathic pain induced by peripheral nerve injury is a complex and chronic state that is accompanied by poor quality of life. However, whether PIM1 (proviral integration site 1) contributes to the development of nociceptive hypersensitivity induced by nerve injury remains unknown. The present study was designed to investigate the effects of PIM1 on spinal nerve ligation (SNL) induced pain hypersensitivity. Here, we found that PIM1 positive neurons in the dorsal root ganglion (DRG) were colocalized with nociceptive neuronal markers CGRP, IB4 and substance P and were upregulated after SNL surgery. Knockdown PIM1 in the DRG by AAV5-shPIM1 alleviated SNL-induced pain hypersensitivity. In neuroblastoma cells (neuro-2a), PIM1 regulated the expression of CXCR4 phosphorylated at ser339 (pCXCR4) as well as the CXCL12/CXCR4 pathway. In the DRG tissues, we found that PIM1 was co-expressed with CXCR4, and knockdown of PIM1 attenuated pCXCR4 (ser339) protein expression but had little effect on total CXCR4 protein expression after SNL surgery. These findings suggest that PIM1 contributes to nerve injury-induced nociceptive hypersensitivity. Based on these findings and the characteristics of PIM1, we speculate that PIM1 might be a viable therapeutic target for the treatment of neuropathic pain in the near future.

Pim-1 as a Therapeutic Target in Lupus Nephritis

OBJECTIVE

Lupus nephritis (LN) is a major determinant of morbidity and mortality in systemic lupus erythematosus (SLE). Pim-1 regulates lymphocyte proliferation and activation. The role of Pim-1 in autoimmune disease remains unclear. This study was undertaken to test the hypothesis that inhibition of Pim-1 would have therapeutic potential in patients with LN.

METHODS

Pim-1 expression was analyzed in lupus-prone (NZB × NZW)F1 mice (n = 6), human peripheral blood mononuclear cells (PBMCs) from SLE patients (n = 10), and glomeruli from patients with LN (n = 8). The therapeutic effect of the Pim-1 inhibitor AZD1208 was assessed in the same murine lupus model (n = 10 mice per group). In vitro analysis was conducted to explore the mechanisms of action of Pim-1 in mouse and human podocytes after Pim-1 expression had been induced by anti-double-stranded DNA (anti-dsDNA) antibody-positive serum. Finally, MRL/lpr mice were used to confirm the therapeutic effects of Pim-1 inhibition in vivo (n = 10 mice per group).

RESULTS

Up-regulation of Pim-1 was seen in renal lysates from diseased (NZB × NZW)F1 mice and in PBMCs from patients with SLE and renal biopsy tissue from patients with LN, relative to their control counterparts (each P < 0.05). The Pim-1 inhibitor AZD1208 reduced the severity of proteinuria, glomerulonephritis, renal immune complex deposits, and serum anti-dsDNA antibody levels, concomitant with the suppression of NFATc1 expression and NLRP3 inflammasome activation, in diseased (NZB × NZW)F1 mice (each P < 0.05 versus controls). Moreover, in mouse and human podocytes, Pim-1 knockdown with targeted small interfering RNA (siRNA) suppressed NFATc1 and NLRP3 inflammasome signaling in the presence of anti-dsDNA-positive serum (each P < 0.05 versus control siRNA). Mechanistically, Pim-1 modulated NLRP3 inflammasome activation through intracellular Ca²⁺ (P < 0.05 versus normal controls). The therapeutic effect of Pim-1 blockade was replicated in MRL/lpr mice.

CONCLUSION

These data identify Pim-1 as a critical regulator of LN pathogenesis in patients with SLE. Targeting of the Pim-1/NFATc1/NLRP3 pathway might therefore have therapeutic potential in human LN.

PIM inhibitor SMI-4a induces cell apoptosis in B-cell acute lymphocytic leukemia cells via the HO-1-mediated JAK2/STAT3 pathway

OBJECTIVES

The serine/threonine PIM protein kinases are critical regulators of tumorigenesis in multiple cancers. However, whether PIMs are potential therapeutic targets for treating B-cell acute lymphocytic leukemia (B-ALL) remains unclear. Therefore, here, PIM expression was detected in B-ALL patients and the effects of SMI-4a, a pan-PIM small molecule inhibitor, were investigated in B-ALL cells.

METHODS

PIM1 and PIM2 expression in 26 newly diagnosed B-ALL cases was detected by real-time PCR and Western blot. B-ALL cells were treated with varied SMI-4a doses and the viability of treated cells was investigated using a cell-counting kit-8 (CCK-8) assay. Apoptosis and cell cycles were analyzed by flow cytometry. Western blot analysis was then used to explore the expression of apoptosis-related proteins and the JAK2/STAT3 pathway.

RESULTS

PIM1 and 2 were overexpressed in B-ALL patients with high HO-1 level. SMI-4a induced decreases in PIMs and HO-1 expressions and inhibited B-ALL cell viability. Treatment with SMI-4a induced apoptosis by downregulating Bcl-2, upregulating Bax and other antiapoptotic proteins, and decreasing protein levels of p-JAK2 and p-STAT3. In addition, upregulation of HO-1 alleviated decrease in p-JAK2 and p-STAT3 expression, reduced SMI-4a-induced apoptosis of B-ALL cells, and influenced B-ALL cell survival.

CONCLUSIONS

PIMs were highly expressed in B-ALL patients. SMI-4a inhibited B-ALL proliferation and induced apoptosis via the HO-1-mediated JAK2/STAT3 pathway. SMI-4a might be applicable for treatment of B-ALL cells.

PIM Kinase as an Executional Target in Cancer

PIM (proviral integration site for moloney murine leukemia virus) kinase plays a key role as an oncogene in various cancers including myeloma, leukemia, prostate and breast cancers. The aberrant expression and/or activation of PIM kinases in various cancers follow an isoform-specific pattern. While PIM1 is predominantly expressed in hematological and solid tumors, PIM2 and PIM3 are largely expressed in leukemia and solid tumors, respectively. All of PIM kinases cause transcriptional activation of genes involved in cell survival and cell cycle progression in cancer. A variety of pro-tumorigenic signaling molecules, such as MYC, p21^Cip1/Waf1/p27^kip1, CDC25, Notch1 and BAD have been identified as the downstream targets of PIM kinases. So far, three kinds of adenosine triphosphate-competitive PIM inhibitors, SGI-1776, AZD1208, and LGH447 have been in clinical trials for the treatment of acute myelogenous leukemia, prostate cancer, lymphoma, or multiple myeloma. This review sheds light on the signaling pathways involved in the PIM kinase regulation and current status of developing PIM kinase inhibitors as clinical success in combating human cancer.

Microenvironment-induced PIM kinases promote CXCR4-triggered mTOR pathway required for chronic lymphocytic leukaemia cell migration

Lymph node microenvironment provides chronic lymphocytic leukaemia (CLL) cells with signals promoting their survival and granting resistance to chemotherapeutics. CLL cells overexpress PIM kinases, which regulate apoptosis, cell cycle and migration. We demonstrate that BCR crosslinking, CD40 stimulation, and coculture with stromal cells increases PIMs expression in CLL cells, indicating microenvironment‐dependent PIMs regulation. PIM1 and PIM2 expression at diagnosis was higher in patients with advanced disease (Binet C vs. Binet A/B) and in those, who progressed after first‐line treatment. In primary CLL cells, inhibition of PIM kinases with a pan‐PIM inhibitor, SEL24‐B489, decreased PIM‐specific substrate phosphorylation and induced dose‐dependent apoptosis in leukaemic, but not in normal B cells. Cytotoxicity of SEL24‐B489 was similar in TP53‐mutant and TP53 wild‐type cells. Finally, inhibition of PIM kinases decreased CXCR4‐mediated cell chemotaxis in two related mechanisms‐by decreasing CXCR4 phosphorylation and surface expression, and by limiting CXCR4‐triggered mTOR pathway activity. Importantly, PIM and mTOR inhibitors similarly impaired migration, indicating that CXCL12‐triggered mTOR is required for CLL cell chemotaxis. Given the microenvironment‐modulated PIM expression, their pro‐survival function and a role of PIMs in CXCR4‐induced migration, inhibition of these kinases might override microenvironmental protection and be an attractive therapeutic strategy in this disease.

A novel, dual pan-PIM/FLT3 inhibitor SEL24 exhibits broad therapeutic potential in acute myeloid leukemia

Fms-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) is one of the most common genetic lesions in acute myeloid leukemia patients (AML). Although FLT3 tyrosine kinase inhibitors initially exhibit clinical activity, resistance to treatment inevitably occurs within months. PIM kinases are thought to be major drivers of the resistance phenotype and their inhibition in relapsed samples restores cell sensitivity to FLT3 inhibitors. Thus, simultaneous PIM and FLT3 inhibition represents a promising strategy in AML therapy. For such reasons, we have developed SEL24-B489 - a potent, dual PIM and FLT3-ITD inhibitor. SEL24-B489 exhibited significantly broader on-target activity in AML cell lines and primary AML blasts than selective FLT3-ITD or PIM inhibitors. SEL24-B489 also demonstrated marked activity in cells bearing FLT3 tyrosine kinase domain (TKD) mutations that lead to FLT3 inhibitor resistance. Moreover, SEL24-B489 inhibited the growth of a broad panel of AML cell lines in xenograft models with a clear pharmacodynamic-pharmacokinetic relationship. Taken together, our data highlight the unique dual activity of the SEL24-B489 that abrogates the activity of signaling circuits involved in proliferation, inhibition of apoptosis and protein translation/metabolism. These results underscore the therapeutic potential of the dual PIM/FLT3-ITD inhibitor for the treatment of AML.

Biology of classical Hodgkin lymphoma: implications for prognosis and novel therapies

Hodgkin lymphoma is considered a prime example of treatment success, with cure rates exceeding 80% using modern combined modality therapies. However, especially in adolescents and young adults, treatment-related toxicity and long-term morbidity still represent persistent challenges. Moreover, outcomes in patients with relapsed or refractory disease remain unfavorable in the era of high-dose chemotherapy and stem-cell transplantation. Hence, there is a high demand for novel and innovative alternative treatment approaches. In recent years, many new therapeutic agents have emerged from preclinical and clinical studies that target molecular hallmarks of Hodgkin lymphoma, including the aberrant phenotype of the tumor cells, deregulated oncogenic pathways, and immune escape. The antibody-drug conjugate brentuximab vedotin and immune checkpoint inhibitors have already shown great success in patients with relapsed/refractory disease, leading to US Food and Drug Administration approval and new trials testing these agents in various clinical settings. The expanding knowledge and understanding of Hodgkin lymphoma biology and disease progression, as well as the development of robust tools for biomarker-driven risk stratification and therapeutic decision making, continue to be fundamentally important for the success of these and other novel agents. We anticipate that the availability and clinical implementation of novel molecular assays will be instrumental in an era of rapid shifts in the treatment landscape of this disease. Here, we review the current knowledge of Hodgkin lymphoma pathobiology, highlighting the related development of novel treatment strategies and prognostic models that hold the promise to continually challenge and change the current standard of care in classical Hodgkin lymphoma.

Quercetin Therapy for Selected Patients with PIM1 Kinase-Positive Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma: A Pilot Study

We reported that PIM1 kinase is expressed in the lymphocytes of patients with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). Quercetin, a naturally occurring flavonoid, is a dietary supplement and inhibits many kinases, including PIM1, in vitro. Under an Institutional Review Board-approved protocol, we performed an open-label, single-arm pilot study to evaluate the antitumor activity of quercetin in patients with CLL/SLL. Q-ForceTM chews were administered orally, 500 mg twice daily, for 3 months. Eligible patients had failed prior therapies, had had no other standard treatment, or refused other therapies. Response was assessed based on objective change in disease parameters. Patients were included if their lymphocyte counts were rising and ≥10,000/µL but not > 100,000/µL. Three patients received quercetin treatment. There was no toxicity. Two responded with stabilization of rising lymphocyte counts (p < 0.001 for each), which remained stable during their follow-up (5 and 11 months after cessation of treatment, respectively). The CLL cells in the nonresponder harbored a TP53 mutation. Although our data from this pilot translational study are based on a small sample, further studies of quercetin as a potential therapeutic agent in selected patients with CLL/SLL appear warranted.

Potential for subsets of wt-NPM1 primary AML blasts to respond to retinoic acid treatment

Acute myeloid leukemia (AML) has high mortality rates, perhaps reflecting a lack of understanding of the molecular diversity in various subtypes and a lack of known actionable targets. There are currently 12 open clinical trials for AML using combination therapeutic modalities including all-trans retinoic acid (RA). Mutant nucleophosmin-1, proposed as a possible marker for RA response, is the criterion for recruiting patients in three active RA phase 3 clinical trials. We tested the ability of RA alone or in combination with either bosutinib (B) or 6-formylindolo(3,2-b) carbazole (F) to induce conversion of 12 de novo AML samples toward a more differentiated phenotype. We assessed levels of expression of cell surface markers associated with differentiation, aldehyde dehydrogenase activity, and glucose uptake activity. Colony formation capacity was reduced with the combined treatment of RA and B or F, and correlated with modulation of a c-Cbl/Lyn/c-Raf-centered signalsome. Combination treatment was in most cases more effective than RA alone. Based on their responses to the treatments, some primary leukemic samples cluster closer to HL-60 cells than to other primary samples, suggesting that they may represent a hitherto undefined AML subtype that is potentially responsive to RA in a combination differentiation therapy.

Mutational profile of primary breast diffuse large B-cell lymphoma

Primary breast lymphoma is a rare form of extra-nodal lymphoid neoplasm. The most common histological type is the diffuse large B-cell lymphoma, which represents 60–80% of all the cases. Our study analyzes the mutational profile of the primary lymphoma of the breast through targeted massive sequencing with a panel of 38 genes in a group of 17 patients with primary breast diffuse large B-cell lymphoma. Seventy-point-five percent of the patients presented with stage IE and 29.5% with stage IIE. 44% of the cases correspond to lymphomas with germinal center phenotype and 33.3% to activated B-cell. The genes with a higher mutational frequency include PIM1 (in 50% of the analyzed samples), MYD88 (39%), CD79B, PRDM1 and CARD11 (17%), KMT2D, TNFIAP3 and CREBBP (11%). The profile of mutant genes involves mostly the NFκB signaling pathway. The high frequency of mutations in PIM1 compared with other lymphomas may have implications in the clinical presentation and evolution of this type of lymphoma.