Shim, Kevin G

ABSTRACT Background Immunomodulatory agents (IMiDs) are a cornerstone in the successful management of multiple myeloma (MM). However, acquired IMiD resistance leading to disease relapses remains a major barrier. Hydrogen peroxide generation and oxidative stress are key mediators that determine IMiD's effectiveness in MM. Iron plays a key role in the generation of oxidative stress; therefore, cellular iron levels are tightly governed. FTH1 is the major iron storage protein that tightly regulates cellular iron availability. Hence, the present study is targeted to investigate the role of FTH1 in MM and IMiD resistance. Methods IMiD‐sensitive and IMiD‐resistant MM cells were analyzed for expression of iron‐metabolism genes. CRISPR‐cas9‐mediated knockout of FTH1 was performed and the after‐effects were assessed through multiple experiments. Results Initial analysis showed a positive correlation between FTH1 expression and IMiD resistance in MM cells. FTH1 ‐KO reduced IMiD sensitivity in the KMS11 cell line but had no effect on the RPMI8226 cell line. RNA‐seq data showed downregulation of ER‐stress and calcium signaling genes after FTH1 ‐KO. Further, KMS11‐ FTH1 KO cells exhibited lower intracellular ROS, labile‐iron, and mitochondrial superoxide levels along with increased CD63, suggesting activation of L‐ferritin secretory pathways. Conclusion Data reveals a link between FTH1 , labile iron, ROS, and IMiD resistance in MM cells.

ABSTRACTCronkhite‐Canada Syndrome (CCS) is a rare non‐hereditary gastroenterological polyposis syndrome without a clear etiology. Myelodysplastic syndromes (MDS) are clonal hematological disorders. Immune dysregulation has been posited as a contributor to the development of both. A 70‐year‐old man developed chronic diarrhea, dysgeusia, and onycholysis. Endoscopic evaluation and testing to exclude hereditary polyposis syndromes resulted in a diagnosis of CCS. Approximately 1 year later, he was noted to have persistent anemia, which was ultimately diagnosed as MDS. He was evaluated with a myeloid disorder next‐generation sequencing panel and found to have mutations in IDH2, SRSF2, and JAK2. This is the second reported case characterizing concomitant MDS and CCS. This is the first case to report the development of MDS after the diagnosis and treatment of CCS. A successful management strategy for both disorders is outlined within this case report.

Several novel T-cell-based therapies have recently become available for multiple myeloma (MM). These T-cell redirecting therapies (TRTs) include chimeric antigen receptor T-cells (CAR-T) and bispecific antibodies (BiAbs). In both clinical trial and real-world data, these therapies have demonstrated high rates of deep clinical response, and some are now approved for second-line treatment for relapsed MM. The deep and sustained clinical responses these therapies are capable of inducing will require sophisticated response monitoring to provide meaningful information for patient care. Obtaining measurable residual disease (MRD) negativity has been validated as an independent positive prognostic marker for progression-free survival (PFS) and overall survival (OS) in both newly diagnosed and relapsed refractory patients with multiple myeloma. Assessment for MRD negativity was performed in all of the trials for FDA-approved TRT. Here, we summarize pertinent data for MRD assessment following TRT in MM and provide a rationale and structured framework for conducting MRD testing post TRT.

Abstract Antitumor T-cell responses raised by first-line therapies such as chemotherapy, radiation, tumor cell vaccines, and viroimmunotherapy tend to be weak, both quantitatively (low frequency) and qualitatively (low affinity). We show here that T cells that recognize tumor-associated antigens can directly kill tumor cells if used at high effector-to-target ratios. However, when these tumor-reactive T cells were present at suboptimal ratios, direct T-cell–mediated tumor cell killing was reduced and the ability of tumor cells to evolve away from a coapplied therapy (oncolytic or suicide gene therapy) was promoted. This T-cell–mediated increase in therapeutic resistance was associated with C to T transition mutations that are characteristic of APOBEC3 cytosine deaminase activity and was induced through a TNFα and protein kinase C–dependent pathway. Short hairpin RNA inhibition of endogenous APOBEC3 reduced rates of tumor escape from oncolytic virus or suicide gene therapy to those seen in the absence of antitumor T-cell coculture. Conversely, overexpression of human APOBEC3B in tumor cells enhanced escape from suicide gene therapy and oncolytic virus therapy both in vitro and in vivo. Our data suggest that weak affinity or low frequency T-cell responses against tumor antigens may contribute to the ability of tumor cells to evolve away from first-line therapies. We conclude that immunotherapies need to be optimized as early as possible so that, if they do not kill the tumor completely, they do not promote treatment resistance.

Abstract Purpose: Virotherapies are maturing in the clinical setting. Adenoviruses (Ad) are excellent vectors for the manipulability and tolerance of transgenes. Poor tumor selectivity, off-target sequestration, and immune inactivation hamper clinical efficacy. We sought to completely redesign Ad5 into a refined, tumor-selective virotherapy targeted to αvβ6 integrin, which is expressed in a range of aggressively transformed epithelial cancers but nondetectable in healthy tissues. Experimental Design: Ad5NULL-A20 harbors mutations in each major capsid protein to preclude uptake via all native pathways. Tumor-tropism via αvβ6 targeting was achieved by genetic insertion of A20 peptide (NAVPNLRGDLQVLAQKVART) within the fiber knob protein. The vector's selectivity in vitro and in vivo was assessed. Results: The tropism-ablating triple mutation completely blocked all native cell entry pathways of Ad5NULL-A20 via coxsackie and adenovirus receptor (CAR), αvβ3/5 integrins, and coagulation factor 10 (FX). Ad5NULL-A20 efficiently and selectively transduced αvβ6+ cell lines and primary clinical ascites-derived EOC ex vivo, including in the presence of preexisting anti-Ad5 immunity. In vivo biodistribution of Ad5NULL-A20 following systemic delivery in non–tumor-bearing mice was significantly reduced in all off-target organs, including a remarkable 107-fold reduced genome accumulation in the liver compared with Ad5. Tumor uptake, transgene expression, and efficacy were confirmed in a peritoneal SKOV3 xenograft model of human EOC, where oncolytic Ad5NULL-A20–treated animals demonstrated significantly improved survival compared with those treated with oncolytic Ad5. Conclusions: Oncolytic Ad5NULL-A20 virotherapies represent an excellent vector for local and systemic targeting of αvβ6-overexpressing cancers and exciting platforms for tumor-selective overexpression of therapeutic anticancer modalities, including immune checkpoint inhibitors. Clin Cancer Res; 24(17); 4215–24. ©2018 AACR.

AbstractUnderstanding how incompletely cleared primary tumors transition from minimal residual disease (MRD) into treatment-resistant, immune-invisible recurrences has major clinical significance. We show here that this transition is mediated through the subversion of two key elements of innate immunosurveillance. In the first, the role of TNFα changes from an antitumor effector against primary tumors into a growth promoter for MRD. Second, whereas primary tumors induced a natural killer (NK)–mediated cytokine response characterized by low IL6 and elevated IFNγ, PD-L1hi MRD cells promoted the secretion of IL6 but minimal IFNγ, inhibiting both NK-cell and T-cell surveillance. Tumor recurrence was promoted by trauma- or infection-like stimuli inducing VEGF and TNFα, which stimulated the growth of MRD tumors. Finally, therapies that blocked PD-1, TNFα, or NK cells delayed or prevented recurrence. These data show how innate immunosurveillance mechanisms, which control infection and growth of primary tumors, are exploited by recurrent, competent tumors and identify therapeutic targets in patients with MRD known to be at high risk of relapse. Cancer Immunol Res; 5(11); 1029–45. ©2017 AACR.

Key PointsThe loss of the two most abundant eosinophil granule proteins disrupts the production of blood eosinophils from marrow progenitors. Knockout animals deficient for both MBP-1 and EPX represent a novel strain of mice with a specific and congenital loss of eosinophils.