Cardiac Toxicity Associated with Immune Checkpoint Inhibitors: Case Series and Review of the Literature.

The development of immune checkpoint inhibitors (ICIs) has revolutionized the treatment of patients with advanced stage cancers. However, immune-related adverse events are frequently observed. Cardiac toxicity from ICI therapy can range from asymptomatic troponin-I elevations to conduction abnormalities of the heart and even fulminant myocarditis. Although rare, myocarditis is a potentially fatal adverse effect of ICI therapy. We present a series of five cases of ICI-related cardio-toxicity diagnosed and managed at Roswell Park Comprehensive Cancer Center along with a review of published case reports in the literature. Our series highlights the importance of high clinical suspicion, early diagnosis of myocarditis, and prompt initiation of immunosuppressive therapy.

All-trans-retinoic-acid and arsenic trioxide induced remission in promyelocytic blast crisis.

A 78-year-old-male with chronic myeloid leukemia (CML) treated for seven years with dasatinib developed an acute promyelocytic leukemia complicated by disseminated intravascular coagulopathy. A promyelocytic blast crisis was diagnosed by demonstrating co-expression of chimeric BCL/ABL and PML/RARα translocations by karyotyping, fluorescence in situ hybridization, and quantitative real-time polymerase chain reaction. Promyelocytic blast crisis of CML is a rare event with historically poor outcomes. Treatment of our patient with all-trans-retinoic acid (ATRA) and arsenic trioxide (ATO) resulted in complete morphologic remission. We review here the relevant literature of promyelocytic blast crisis and highlight the potential of ATRA/ATO as first line management.

The neuroprotective effect of Klotho is mediated via regulation of members of the redox system.

Generation of reactive oxygen species (ROS), leading to oxidative damage and neuronal cell death, plays an important role in the pathogenesis of neurodegenerative disorders, including Alzheimer disease. The present study aimed to examine the mechanism by which the anti-aging protein Klotho exerts neuroprotective effects against neuronal damage associated with neurodegeneration and oxidative stress. Pretreatment of rat primary hippocampal neurons and mouse hippocampal neuronal cell line HT22 with recombinant Klotho protected these cells from glutamate and oligomeric amyloid ß (oAß)-induced cytotoxicity. In addition, primary hippocampal neurons obtained from Klotho-overexpressing mouse embryos were more resistant to both cytotoxic insults, glutamate and oAß, compared with neurons from wild-type littermates. An antioxidative stress array analysis of neurons treated with Klotho revealed that Klotho significantly enhances the expression of the thioredoxin/peroxiredoxin (Trx/Prx) system with the greatest effect on the induction of Prx-2, an antioxidant enzyme, whose increase was confirmed at the mRNA and protein levels. Klotho-induced phosphorylation of the PI3K/Akt pathway, a pathway important in apoptosis and longevity, was associated with sustained inhibitory phosphorylation of the transcription factor forkhead box O3a (FoxO3a) and was essential for the induction of Prx-2. Down-regulation of Prx-2 expression using a lentivirus harboring shRNA almost completely abolished the ability of Klotho to rescue neurons from glutamate-induced death and significantly, but not completely, inhibited cell death mediated by oAß, suggesting that Prx-2 is a key modulator of neuroprotection. Thus, our results demonstrate, for the first time, the neuroprotective role of Klotho and reveal a novel mechanism underlying this effect.

Hsp70-Bag3 interactions regulate cancer-related signaling networks.

Bag3, a nucleotide exchange factor of the heat shock protein Hsp70, has been implicated in cell signaling. Here, we report that Bag3 interacts with the SH3 domain of Src, thereby mediating the effects of Hsp70 on Src signaling. Using several complementary approaches, we established that the Hsp70-Bag3 module is a broad-acting regulator of cancer cell signaling by modulating the activity of the transcription factors NF-κB, FoxM1, Hif1α, the translation regulator HuR, and the cell-cycle regulators p21 and survivin. We also identified a small-molecule inhibitor, YM-1, that disrupts the Hsp70-Bag3 interaction. YM-1 mirrored the effects of Hsp70 depletion on these signaling pathways, and in vivo administration of this drug was sufficient to suppress tumor growth in mice. Overall, our results defined Bag3 as a critical factor in Hsp70-modulated signaling and offered a preclinical proof-of-concept that the Hsp70-Bag3 complex may offer an appealing anticancer target.

Proteotoxicity is not the reason for the dependence of cancer cells on the major chaperone Hsp70.

Several years ago a hypothesis was proposed that the survival of cancer cells depend on elevated expression of molecular chaperones because these cells are prone to proteotoxic stress. A critical prediction of this hypothesis is that depletion of chaperones in cancer cells should lead to proteotoxicity. Here, using the major chaperone Hsp70 as example, we demonstrate that its depletion does not trigger proteotoxic stress, thus refuting the model. Accordingly, other functions of chaperones, e.g., their role in cell signaling, might define the requirements for chaperones in cancer cells, which is critical for rational targeting Hsp70 in cancer treatment.