Dihydronicotinamide riboside (NRH):quinone oxidoreductase 2 (NQO2) is a flavoenzyme that catalyzes the reductive metabolism of quinones. To examine the in vivo role of NQO2, NQO2-null (NQO2؊/؊) mice were generated using targeted gene disruption. Mice lacking NQO2 gene expression showed no detectable developmental abnormalities and were indistinguishable from wild-type (NQO2؉/؉) mice. However, NQO2-null mice exhibited myeloid hyperplasia of the bone marrow and increased neutrophils, basophils, eosinophils, and platelets in the peripheral blood. Decreased apoptosis of bone marrow cells and circulating granulocytes contributed to myeloid hyperplasia and hyperactivity of bone marrow in NQO2-null mice. The hematological changes in NQO2؊/؊ mice were specifically associated with loss of the NQO2 gene because histological analysis of various tissues including spleen, thymus, blood cultures, and urine analysis demonstrated no sign of infection. NQO2-null mice also demonstrated decreased toxicity when exposed to menadione or menadione with NRH. These results establish a role for NQO2 in protection against myelogenous hyperplasia and in metabolic activation of menadione, leading to hepatic toxicity. The NQO2-null mice are a model for NQO2 deficiency in humans and can be used to determine the role of this enzyme in sensitivities to toxicity and carcinogenesis.

Immuno-oncology therapies engage the immune system to treat cancer. BiTE (bispecific T-cell engager) technology is a targeted immuno-oncology platform that connects patients' own T cells to malignant cells. The modular nature of BiTE technology facilitates the generation of molecules against tumor-specific antigens, allowing off-the-shelf immuno-oncotherapy. Blinatumomab was the first approved canonical BiTE molecule and targets CD19 surface antigens on B cells, making blinatumomab largely independent of genetic alterations or intracellular escape mechanisms. Additional BiTE molecules in development target other hematologic malignancies (eg, multiple myeloma, acute myeloid leukemia, and B-cell non-Hodgkin lymphoma) and solid tumors (eg, prostate cancer, glioblastoma, gastric cancer, and small-cell lung cancer). BiTE molecules with an extended half-life relative to the canonical BiTE molecules are also being developed. Advances in immuno-oncology made with BiTE technology could substantially improve the treatment of hematologic and solid tumors and offer enhanced activity in combination with other treatments. Cancer 2020;126:3192-3201.

Abstract. Landgren O, Iskander K (Memorial SloanKettering Cancer Center, New York, NY, USA; Amgen, Thousand Oaks, CA, USA). Modern multiple myeloma therapy: deep, sustained treatment response and good clinical outcomes. J Intern Med 2017; 281: 365-382.In the USA at the beginning of this century, the average overall survival in patients with multiple myeloma was about 3 years. Around that time, three drugs (bortezomib, lenalidomide and thalidomide) were introduced for the treatment of multiple myeloma and, in 2012, carfilzomib received accelerated approval by the US Food and Drug Administration (FDA). Driven by access to better drugs, median overall survival in younger patients (aged <50 years) was >10 years by 2014. The FDA approved 14 new drugs for the treatment of cancer in 2015; four of these were approved for the treatment of myeloma (panobinostat, daratumumab, elotuzumab and ixazomib). In 2015 and 2016, expanded label indications were approved by the FDA for lenalidomide and carfilzomib, respectively. The recent increase in approved, highly effective combination therapies for patients with multiple myeloma has led the way to redefining the goals of therapy. Here, we review and provide a clinical perspective on the treatment goals and management of multiple myeloma in the era of modern therapy. Recent meta-analyses show that minimal residual disease (MRD) negativity is associated with longer progression-free and overall survival in patients with multiple myeloma. With the use of modern combination therapy, large proportions (>60-70%) of newly diagnosed multiple myeloma patients achieve complete responses and MRD negativity. Modern combination therapies induce rapid, deep and sustainable responses (including MRD negativity), supporting a treatment paradigm shift away from palliative two-drug combinations towards the use of modern, potent, three-or four-drug combination regimens in early lines of therapy. Data support the use of modern therapy upfront rather than reserving it for later stages of the disease. As survival time increases with modern combination therapies, development of early reliable surrogate end-points for survival, such as MRD negativity, are needed for expedited read-out of future randomized clinical trials.

Tumor suppressor p53 is either lost or mutated in several types of cancer. MDM2 interaction with p53 results in ubiquitination and 26S proteasomal degradation of p53. Chronic DNA damage leads to inactivation of MDM2, stabilization of p53, and apoptotic cell death. Here, we present a novel MDM2/ubiquitination-independent mechanism of stabilization and transient activation of p53. The present studies show that 20S proteasomes degrade p53. The 20S degradation of p53 was observed in ubiquitin-efficient and -deficient cells, indicating that this pathway of degradation did not require ubiquitination of p53. The cytosolic quinone oxidoreductases [NRH:quinone oxidoreductase 2 (NQO2) and NAD(P)H:quinone oxidoreductase 1 (NQO1)] interacted with p53 and protected p53 against 20S proteasomal degradation. Further studies revealed that acute exposure to radiation or chemical leads to induction of NQO1 and NQO2 that stabilizes and transiently activates p53 and downstream genes. These results suggest that stress-induced NQO1 and NQO2 transiently stabilize p53, which leads to protection against adverse effects of stressors. [Cancer Res 2007;67(11):5380-8]

NAD(P)H:quinone oxidoreductase 1 (NQO1) is a cytosolic protein that catalyzes metabolic detoxification of quinones and protects cells against redox cycling and oxidative stress. NQO1 -null mice deficient in NQO1 protein showed increased sensitivity to 7,12-dimethylbenz(a)anthraceneand benzo(a)pyrene-induced skin carcinogenesis. In the present studies, we show that benzo(a )pyrene metabolite benzo(a)pyrene-trans -7,8-dihydrodiol-9,10-epoxide and not benzo(a)pyrene quinones contributed to increased benzo(a)pyrene-induced skin tumors in NQO1-null mice. An analysis of untreated skin revealed an altered intracellular redox state due to accumulation of NADH and reduced levels of NAD/NADH in NQO1-null mice as compared with wild-type mice. Treatment with benzo(a)pyrene failed to significantly increase p53 and apoptosis in the skin of NQO1-null mice when compared with wild-type mice. These results led to the conclusion that altered intracellular redox state along with lack of induction of p53 and decreased apoptosis plays a significant role in increased sensitivity of NQO1-null mice to benzo(a) pyrene-induced skin cancer. (Cancer Res 2005; 65(6): 2054-8)