Clonal Hematopoiesis and Therapy-Related Myeloid Neoplasms After Autologous Transplant for Hodgkin Lymphoma.

PURPOSE: Therapy-related myeloid neoplasm (t-MN) is a life-threatening complication of autologous peripheral blood stem cell transplantation (aPBSCT) for Hodgkin lymphoma (HL). Although previous studies have reported an association between clonal hematopoiesis (CH) in the infused PBSC product and subsequent post-aPBSCT risk of t-MN in patients with non-HL, information about patients with HL treated with aPBSCT is not available. METHODS: We constructed a retrospective cohort of 321 patients with HL transplanted at a median age of 34 years (range, 18-71). Targeted DNA sequencing of PBSC products performed for CH-associated or myeloid malignancy-associated genes identified pathogenic mutations in these patients. RESULTS: CH was identified in the PBSC product of 46 patients (14.3%) with most prominent representation of DNMT3A (n = 25), PPM1D (n = 7), TET2 (n = 7), and TP53 (n = 5) mutations. Presence of CH in the PBSC product was an independent predictor of t-MN (adjusted hazard ratio [aHR], 4.50 [95% CI, 1.54 to 13.19]). Notably all patients with TP53 mutations in the PBSC product developed t-MN, whereas none of the patients with DNMT3A mutations alone (without co-occurring TP53 or PPM1D mutations) did. Presence of TP53 and/or PPM1D mutations was associated with a 7.29-fold higher hazard of t-MN when compared with individuals carrying no CH mutations (95% CI, 1.72 to 30.94). The presence of TP53 and/or PPM1D mutations was also associated with a 4.17-fold higher hazard of nonrelapse mortality (95% CI, 1.25 to 13.87). There was no association between CH and relapse-related mortality. CONCLUSION: The presence of TP53 and/or PPM1D mutations in the PBSC product increases the risk of post-aPBSCT t-MN and nonrelapse mortality among patients with HL and may support alternative therapeutic strategies.

The uncharted role of HER2 mutant alleles in breast cancer.

Somatic HER2 mutations are a novel class of therapeutic targets across different cancer types. Treatment with the tyrosine kinase inhibitor (TKI) neratinib as a single agent continues to be evaluated in HER2-mutant metastatic disease. However, responses are heterogeneous, with frequent early progression. Herein, we discuss the under-explored effects of individual HER2 mutant alleles on therapeutic response, a role for HER2 mutation in metastatic propensity, and differences in patient outcomes in ER+ invasive lobular carcinoma (ILC) versus invasive ductal carcinoma (IDC). The preclinical efficacy of additional agents is also discussed, particularly the pan-HER inhibitor poziotinib.

Poziotinib Inhibits HER2-Mutant-Driven Therapeutic Resistance and Multiorgan Metastasis in Breast Cancer.

The pan-HER tyrosine kinase inhibitor (TKI) neratinib is therapeutically active against metastatic breast cancers harboring activating HER2 mutations, but responses are variable and often not durable. Here we demonstrate that recurrent HER2 mutations have differential effects on endocrine therapy responsiveness, metastasis, and pan-HER TKI therapeutic sensitivity. The prevalence and prognostic significance may also depend on whether the HER2 mutant has arisen in the context of lobular versus ductal histology. The most highly recurrent HER2 mutant, L755S, was particularly resistant to neratinib but sensitive to the pan-HER TKI poziotinib, alone or in combination with fulvestrant. Poziotinib reduced tumor growth, diminished multiorgan metastasis, and inhibited mTOR activation more effectively than neratinib. Similar therapeutic effects of poziotinib were observed in both an engineered HER2L755S MCF7 model and a patient-derived xenograft harboring a HER2G778_P780dup mutation. Overall, these findings support the need for clinical evaluation of poziotinib for the treatment of HER2-mutant metastatic breast cancer. SIGNIFICANCE: Evaluation of the functional impact of HER2 mutations on therapy-induced resistance and metastasis identifies robust antitumor activity of poziotinib and supports the clinical evaluation of poziotinib in ER+ HER2 mutant breast cancer.

Mismatch repair deficiency predicts response to HER2 blockade in HER2-negative breast cancer.

Resistance to endocrine treatment occurs in ~30% of ER+ breast cancer patients resulting in ~40,000 deaths/year in the USA. Preclinical studies strongly implicate activation of growth factor receptor, HER2 in endocrine treatment resistance. However, clinical trials of pan-HER inhibitors in ER+/HER2- patients have disappointed, likely due to a lack of predictive biomarkers. Here we demonstrate that loss of mismatch repair activates HER2 after endocrine treatment in ER+/HER2- breast cancer cells by protecting HER2 from protein trafficking. Additionally, HER2 activation is indispensable for endocrine treatment resistance in MutL- cells. Consequently, inhibiting HER2 restores sensitivity to endocrine treatment. Patient data from multiple clinical datasets supports an association between MutL loss, HER2 upregulation, and sensitivity to HER inhibitors in ER+/HER2- patients. These results provide strong rationale for MutL loss as a first-in-class predictive marker of sensitivity to combinatorial treatment with endocrine intervention and HER inhibitors in endocrine treatment-resistant ER+/HER2- breast cancer patients.

Vitamin D3-VDR-PTPN6 axis mediated autophagy contributes to the inhibition of macrophage foam cell formation.

Macrophage derived foam cells in atherosclerotic plaques are the major factor responsible for the pathogenesis of atherosclerosis (AS). During advanced AS, macrophage-specific macroautophagy/autophagy is dysfunctional. 1, 25-dihydroxy vitamin D3 (VitD3) and its receptor VDR (vitamin D receptor) are reported to inhibit foam cell formation and induce autophagy; however, the role of VitD3-VDR-induced autophagy and foam cell formation in AS has not been explored. Here we find that VitD3 significantly recovered oxidized low-density lipoprotein-impaired autophagy, as well as increased autophagy-mediated lipid breakdown in mouse bone marrow-derived macrophages and human monocyte-derived macrophages, thus inhibiting the conversion of macrophages into foam cells. Importantly, VitD3 functions through its receptor VDR to upregulate autophagy and attenuate the accumulation of lipids in macrophages. Moreover, this study is the first occasion to report the interesting link between VitD3 signaling and PTPN6/SHP-1 (protein tyrosine phosphatase non-receptor type 6) in macrophages. VitD3-induced autophagy was abrogated in the presence of the PTPN6/Ptpn6 shRNA or inhibitor. VDR along with RXRA (retinoid X receptor alpha), and NCOA1 (nuclear receptor coactivator 1), are recruited to a specific response element located on the gene promoter and induce PTPN6 expression. PTPN6 contributes to VitD3-mediated autophagy by regulating autophagy-related genes via activation of MAPK1 (mitogen-activated protein kinase 1) and CEBPB (CCAAT enhancer binding protein beta). Furthermore, expression of PTPN6 is also crucial for VitD3-mediated inhibition of macrophage foam cell formation through autophagy. Thus, VitD3-VDR-PTPN6 axis-regulated autophagy attenuates foam cell formation in macrophages.

The role of positron emission tomography in the selection of patients for salvage hysterectomy following chemoradiotherapy for locally advanced cervical cancer.

BACKGROUND: Patients selection for salvage hysterectomy following chemoradiotherapy of cervical cancer is vital to avoid significant morbidity. The purpose of this study was to describe the role of post-treatment F18-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography scanning (FDG-PET/CT) in patient selection for salvage hysterectomy. METHODS: This was a retrospective analysis of 49 patients with cervical cancer treated between January 1996 and December 2012 who were candidates for salvage hysterectomy. RESULTS: Three groups were defined based on institutional treatment guidelines, as experience in using post-treatment FDG-PET/CT to guide management evolved. Group 1 consisted of 15 patients who underwent planned hysterectomy based on clinical, cytological, or histological suspicion. Of these, only three (20%) patients had residual disease on histology. Group 2 consisted of 13 patients who had post-treatment FDG-PET/CT 3-6 months after the completion of chemoradiotherapy due either to suspicion of recurrence on examination or patients thought to be at high risk of recurrence at the primary site. Of these, eight patients had hysterectomy and four patients showed positive histology for residual tumor. Group 3 had 21 patients who showed isolated FDG uptake at the primary site on first FDG-PET/CT scanning at 6 months. A subsequent FDG-PET/CT scan after 3 months showed disease progression in seven and complete metabolic response in 14, and surgery was avoided in all patients. CONCLUSION: FDG-PET/CT scanning at 6 months after radiotherapy is a good tool for assessing treatment response in patients with cervical cancer. In patients with persistent uptake on 6 months post-treatment FDG-PET/CT, repeat imaging at a 3-month interval helps in selecting patients for salvage hysterectomy.

AIRE promotes androgen-independent prostate cancer by directly regulating IL-6 and modulating tumor microenvironment.

Early stage prostate cancers are dependent on androgens for their growth and survival and androgen withdrawal causes them to regress. Progressive prostate cancers eventually acquire androgen independence rendering anti-androgen therapy ineffective. However, the factors leading to this have not been adequately addressed. This study shows that AIRE finds differential expression in androgen-dependent and -independent prostate cancer cells. AIRE expression is more in androgen-independent cells due to its regulation by transcription factor Elk-1. These enhanced levels of AIRE modulate the prostate tumor microenvironment by transcriptionally activating a malignancy gene IL-6 in androgen-independent cells. Additionally, AIRE prevents the cancer cells from anticancer drug-induced death and enhances their invasiveness. Moreover, AIRE by modulating the cytokine milieu skews the tumor-associated macrophage polarization towards M2 phenotype with increased CD206 and CD163 expression. Subcutaneous mouse model of prostate cancer revealed AIRE+/+ mice forming a palpable tumor and presents lymphadenopathy however, only a small benign tumor is observed in AIRE-/- mice and lymph nodes appear normal in size. In conclusion, our findings suggest AIRE as a probable factor in promoting prostate cancer progression.

An Accord of Nuclear Receptor Expression in M. tuberculosis Infected Macrophages and Dendritic Cells.

Mycobacterium tuberculosis instigates interactions with host factors to promote its survival within the host inimical conditions. Among such factors, nuclear receptors (NRs) seem to be promising candidates owing to their role in bacterial pathogenesis. However, only few members of NR superfamily have been implicated in M. tuberculosis infection and there is a dearth of comprehensive knowledge about expression or function of the entire superfamily. In this study, we performed detailed expression analysis and identified key NRs getting differentially regulated in murine macrophages and dendritic cells (DC) upon infection with H37Rv. The murine macrophages and DCs infected with H37Rv entailed overlapping changes in the expression of certain NRs which reflect upon the possibility that both cells might utilize similar transcriptional programs upon M. tuberculosis infection. We identified Nr4a3 and Rora, which have not been implicated in M. tuberculosis pathogenesis, undergo similar changes in expression in macrophages and DCs upon H37Rv infection. Interestingly, a similar pattern in their expression was also observed in infected human monocyte derived macrophages and the findings corroborated well with PBMCs obtained from TB patients. This all-inclusive analysis provides the basis for a precise approach in identifying NRs that can be targeted therapeutically in intracellular bacterial infections.

A human xenobiotic nuclear receptor contributes to nonresponsiveness of Mycobacterium tuberculosis to the antituberculosis drug rifampicin.

Mycobacterium tuberculosis is the causative agent of tuberculosis (TB). It acquires phenotypic drug resistance inside macrophages, and this resistance mainly arises from host-induced stress. However, whether cellular drug-efflux mechanisms in macrophages contribute to nonresponsiveness of M. tuberculosis to anti-TB drugs is unclear. Here, we report that xenobiotic nuclear receptors mediate TB drug nonresponsiveness by modulating drug-efflux transporters in macrophages. This was evident from expression analysis of drug-efflux transporters in macrophages isolated from TB patients. Among patients harboring rifampicin-susceptible M. tuberculosis, we observed increased intracellular survival of M. tuberculosis upon rifampicin treatment of macrophages isolated from patients not responding to anti-TB drugs compared with macrophages from patients who did respond. Of note, M. tuberculosis infection and rifampicin exposure synergistically modulated macrophage drug-efflux transporters in vitro We also found that the xenobiotic nuclear receptor pregnane X receptor (PXR) modulates macrophage drug-efflux transporter expression and activity, which compromised the anti-TB efficacy of rifampicin. We further validated this finding in a TB mouse model in which use of the PXR antagonist ketoconazole rescued rifampicin anti-TB activity. We conclude that PXR activation in macrophages compromises the efficacy of the anti-TB drug rifampicin. Alternative therapeutic strategies, such as use of the rifampicin derivatives rifapentine and rifabutin, which do not activate PXR, or of a PXR antagonist, may be effective for tackling drug nonresponsiveness of M. tuberculosis that arises from drug-efflux systems of the host.

Human Xenobiotic Nuclear Receptor PXR Augments Mycobacterium tuberculosis Survival.

Mycobacterium tuberculosis can evade host defense processes, thereby ensuring its survival and pathogenesis. In this study, we investigated the role of nuclear receptor, pregnane X receptor (PXR), in M. tuberculosis infection in human monocyte-derived macrophages. In this study, we demonstrate that PXR augments M. tuberculosis survival inside the host macrophages by promoting the foamy macrophage formation and abrogating phagolysosomal fusion, inflammation, and apoptosis. Additionally, M. tuberculosis cell wall lipids, particularly mycolic acids, crosstalk with human PXR (hPXR) by interacting with its promiscuous ligand binding domain. To confirm our in vitro findings and to avoid the reported species barrier in PXR function, we adopted an in vivo mouse model expressing hPXR, wherein expression of hPXR in mice promotes M. tuberculosis survival. Therefore, pharmacological intervention and designing antagonists to hPXR may prove to be a promising adjunct therapy for tuberculosis.

Frienemies of infection: A chronic case of host nuclear receptors acting as cohorts or combatants of infection.

Macrophages and dendritic cells provide critical effector functions to efficiently resist and promptly eliminate infection. Pattern recognition receptors signaling operative in these cell types is imperative for their innate properties. However, it is now emerging that besides these conventional signaling pathways, nuclear receptors coupled gene regulation and transrepression pathways assemble immune regulatory networks. A couple of these networks associated with members of nuclear receptor superfamily decide heterogeneity in macrophages and dendritic cells population and thereby play decisive role in determining protective immunity against bacteria, viruses, fungi, protozoa and helminths. Pathogens also direct shift in the expression of nuclear receptors and their target genes and this is proclaimed to be a sui generis mechanism whereby microbes disconnect the genomic component from the peripheral immune response. Many endogenous and synthetic nuclear receptor ligands have been tested in various in vitro and in vivo infection models to study their effect on pathogen burden. Here, we discuss current advances in our understanding of the composite interactions between nuclear receptor and pathogens and their implications on the causatum infectious diseases.

Nuclear Receptor Nr4a2 Promotes Alternative Polarization of Macrophages and Confers Protection in Sepsis.

The orphan nuclear receptor Nr4a2 is known to modulate both inflammatory and metabolic processes, but the mechanism by which it regulates innate inflammatory homeostasis has not been adequately addressed. This study shows that exposure to ligands for Toll-like receptors (TLRs) robustly induces Nr4a2 and that this induction is tightly regulated by the PI3K-Akt signaling axis. Interestingly, exogenous expression of Nr4a2 in macrophages leads to their alternative phenotype with induction of genes that are prototypical M2 markers. Moreover, Nr4a2 transcriptionally activates arginase 1 expression by directly binding to its promoter. Adoptive transfer experiments revealed that increased survival of animals in endotoxin-induced sepsis is Nr4a2-dependent. Thus our data identify a previously unknown role for Nr4a2 in the regulation of macrophage polarization.