Nao Yoshida-Sakai

Background: The development of newer agents, including anti-CD38 monoclonal antibodies (mAbs), has significantly improved overall survival (OS) in patients with relapsed or refractory multiple myeloma (RRMM). However, the treatment of older patients with RRMM who are transplant-ineligible remains challenging. Methods: We retrospectively evaluated OS in 78 transplant-ineligible patients with RRMM who were aged ≥ 65 years and treated at our institution between February 2012 and November 2023. Results: Unadjusted OS was significantly longer in the anti-CD38 mAb-exposed group (i.e., those previously treated with daratumumab and receiving isatuximab plus pomalidomide and low-dose dexamethasone because of disease progression during treatment with daratumumab [n = 6], daratumumab plus pomalidomide and low-dose dexamethasone [n = 9], or isatuximab plus pomalidomide and low-dose dexamethasone without daratumumab-exposure [n = 14]) than in the anti-CD38 mAb-naïve group (no exposure to daratumumab or isatuximab [n = 49]) (p < 0.001). To address potential confounder factors associated with use or nonuse of anti-CD38 mAbs, we performed propensity score matching (PSM) using age, sex, performance status, and Geriatric 8 and Instrumental Activities of Daily Living scores. PSM identified 14 subjects from the anti-CD38 mAb-exposed group with baseline characteristics similar to those of 14 subjects from the anti-CD38 mAb-naïve group. After PSM, the adjusted OS was significantly longer in the anti-CD38 mAb-exposed group than in the anti-CD38 mAb-naïve group (p < 0.001). Conclusion: These findings provide insights into the optimal use of anti-CD38 mAbs in patients with RRMM who are transplant-ineligible and aged ≥65 years and on candidates who are appropriate for novel approaches, such as chimeric antigen receptor T-cell or bispecific T-cell engager therapy.

5-azacytidine (AZA), a representative DNA-demethylating drug, has been widely used to treat myelodysplastic syndromes (MDS). However, it remains unclear whether AZA’s DNA demethylation of any specific gene is correlated with clinical responses to AZA. In this study, we investigated genes that could contribute to the development of evidence-based epigenetic therapeutics with AZA. A DNA microarray identified that AZA specifically upregulated the expression of 438 genes in AZA-sensitive MDS-L cells but not in AZA-resistant counterpart MDS-L/CDA cells. Of these 438 genes, the ALOX12 gene was hypermethylated in MDS-L cells but not in MDS-L/CDA cells. In addition, we further found that (1) the ALOX12 gene was hypermethylated in patients with MDS compared to healthy controls; (2) MDS classes with excess blasts showed a relatively lower expression of ALOX12 than other classes; (3) a lower expression of ALOX12 correlated with higher bone marrow blasts and a shorter survival in patients with MDS; and (4) an increased ALOX12 expression after AZA treatment was associated with a favorable response to AZA treatment. Taking these factors together, an enhanced expression of the ALOX12 gene may predict favorable therapeutic responses to AZA therapy in MDS.

Adult T-cell leukemia/lymphoma (ATL) is triggered by infection with human T-cell lymphotropic virus-1 (HTLV-1). Here, we describe the reprogramming of pyrimidine biosynthesis in both normal T cells and ATL cells through regulation of uridine-cytidine kinase 2 (UCK2), which supports vigorous proliferation. UCK2 catalyzes the monophosphorylation of cytidine/uridine and their analogues during pyrimidine biosynthesis and drug metabolism. We found that UCK2 was overexpressed aberrantly in HTLV-1–infected T cells but not in normal T cells. T-cell activation via T-cell receptor (TCR) signaling induced expression of UCK2 in normal T cells. Somatic alterations and epigenetic modifications in ATL cells activate TCR signaling. Therefore, we believe that expression of UCK2 in HTLV-1–infected cells is induced by dysregulated TCR signaling. Recently, we established azacitidine-resistant (AZA-R) cells showing absent expression of UCK2. AZA-R cells proliferated normally in vitro, whereas UCK2 knockdown inhibited ATL cell growth. Although uridine and cytidine accumulated in AZA-R cells, possibly because of dysfunction of pyrimidine salvage biosynthesis induced by loss of UCK2 expression, the amount of UTP and CTP was almost the same as in parental cells. Furthermore, AZA-R cells were more susceptible to an inhibitor of dihydroorotic acid dehydrogenase, which performs the rate-limiting enzyme of de novo pyrimidine nucleotide biosynthesis, and more resistant to dipyridamole, an inhibitor of pyrimidine salvage biosynthesis, suggesting that AZA-R cells adapt to UCK2 loss by increasing de novo pyrimidine nucleotide biosynthesis. Taken together, the data suggest that fine-tuning pyrimidine biosynthesis supports vigorous cell proliferation of both normal T cells and ATL cells.

Adult T-cell leukemia/lymphoma (ATL) is a malignancy of mature CD4+ T cells caused by human T-cell lymphotropic virus type 1 (HTLV-1)–induced T-cell transformation. After infection with HTLV-1, it takes several decades for HTLV-1 carriers to develop ATL. The prognosis of ATL remains poor despite several new agents being approved in the last few years. Recently, it has been noted that epigenetic abnormalities, both DNA methylation and trimethylation at histone H3Lys27 (H3K27me3), contribute to ATL leukemogenesis. Here, we investigated the effect of combination treatment with DNA demethylating agents (azacitidine [AZA], decitabine (DAC), and OR-2100 (OR21), which is a silylated derivative of DAC) and inhibitors of enhancer of zeste homolog 2 (EZH2) (EPZ-6438 and DS-3201b), which catalyze trimethylation of H3K27, in ATL. The combination of DAC and OR21 but not AZA with EZH inhibitors exhibited synergistic anti-ATL effects in vitro and in vivo, concomitant with DNA demethylation and reduction of H3K27me3. The combination induced gene expression reprogramming. Dual-specificity phosphatase 5 (DUSP5), an extracellular signal-regulated kinase (ERK)–specific phosphatase, was identified as a key molecule that mediated the inhibitory effect of combination treatment by inactivating the ERK signaling pathway. DUSP5 was downregulated by DNA methylation and H3K27me3 accumulation in the promoter region in HTLV-1–infected cells from patients with ATL during ATL leukemogenesis. The present results demonstrate that dual targeting of aberrant DNA and histone methylation synergistically suppresses tumor cell growth by restoring DUSP5, and that dual targeting of aberrant DNA and histone methylation is a feasible therapeutic approach for ATL.

IC50 in acute myeloid leukemia cell lines (µM)

The Bliss score in combination of venetoclax

Figure S5. The combination effect of venetoclax (Ven) and S63845 (S6) in acute myeloid leukemia.