Phase 1/2 Study Evaluating the Safety and Efficacy of DSP-7888 Dosing Emulsion in Myelodysplastic Syndromes

DSP‐7888 is an immunotherapeutic cancer vaccine derived from the Wilms’ tumor gene 1 (WT1) protein. This phase 1/2 open‐label study evaluated the safety and efficacy of DSP‐7888 dosing emulsion in patients with myelodysplastic syndromes (MDS). DSP‐7888 was administered intradermally (3.5 or 10.5 mg) every 2 weeks for 6 months and then every 2‐4 weeks until lack of benefit. Twelve patients were treated in phase 1 (3.5 mg, n = 6; 10.5 mg, n = 6), with no dose‐limiting toxicities reported. Thus, the 10.5 mg dose was selected as the recommended phase 2 dose, and 35 patients were treated in phase 2. Forty‐seven patients received ≥1 dose of the study drug and comprised the safety analysis set. The most common adverse drug reaction (ADR) was injection site reactions (ISR; 91.5%). Grade 3 ISR were common (58.8%) in phase 1 but occurred less frequently in 2 (22.9%) following implementation of risk minimization strategies. Other common ADR were pyrexia (10.6%) and febrile neutropenia (8.5%). In the efficacy analysis set, comprising patients with higher‐risk MDS after azacitidine failure in phases 1 and 2 (n = 42), the disease control rate was 19.0%, and the median overall survival (OS) was 8.6 (90% confidence interval [CI], 6.8‐10.3) months. Median OS was 10.0 (90% CI, 7.6‐11.4) months in patients with a WT1‐specific immune response (IR; n = 33) versus 4.1 (90% CI, 2.3‐8.1) months in those without a WT1‐specific IR (n = 9; P = .0034). The acceptable safety and clinical activity findings observed support the continued development of DSP‐7888 dosing emulsion.

Differential sensitization of two human colon cancer cell lines to the antitumor effects of irinotecan combined with 5-aza-2'-deoxycytidine

Irinotecan (CPT-11) is a key therapeutic drug used in the treatment of colorectal cancer, although acquired or constitutive resistance to CPT-11 (and its activated metabolite SN-38) can lead to tumor progression. Since the acquisition of drug resistance can result from DNA hypermethylation, the antitumor activity of CPT-11 and SN-38 was assessed in combination with a known DNA methyltransferase inhibitor, 5-aza-2'-deoxycytidine, also known as decitabine (DAC). DAC potentiated the antitumor activity of CPT-11 additively, and that of SN-38 synergistically, as measured by colony formation in the human colorectal cancer HCT116 cell line. No DAC potentiation of these antitumor effects was observed with another human colorectal cancer HT29 cell line. Anti-apoptotic B-cell lymphoma-2 (Bcl-2) protein expression was reduced to 50-67% of the control following a single treatment with CPT-11, SN-38, or DAC, and was markedly reduced to 7-8% following the combination of CPT-11/SN-38 with DAC. By contrast, Bcl-2 protein expression was barely detected in HT29. Wilms' tumor protein (WT1), which has been shown to be a positive regulator of Bcl-2 in HCT116 cells through WT1-kncokdown experiments, was downregulated in HCT116 and HT29 cells when treated with CPT-11/SN-38 combined with DAC, with decreases greater than any single administration of CPT-11, SN-38, or DAC. The extent of CPT-11/SN-38 potentiation by DAC may depend on Bcl-2 expression levels in human colorectal cancer cells.

Wilms' tumor gene 1 transcript levels in leukapheresis of peripheral blood hematopoietic cells predict relapse risk in patients autografted for acute myeloid leukemia

Autologous hematopoietic stem cell transplantation (ASCT) is a curative option alternative to allogeneic transplantation for patients with acute myeloid leukemia (AML). Relapse after ASCT can be due to contamination with leukemic blasts of autologous peripheral blood stem cells (PBSCs) collected by leukapheresis (LK). Identification and quantification of a minimal residual disease (MRD) marker in PBSCs could be relevant in determining the relapse risk after ASCT. High levels of the WT1 gene transcript in bone marrow of AML patients after treatment completion predict disease relapse. We evaluated WT1 transcript levels in autologous PBSC from LK used for ASCT in 30 consecutive AML patients in complete remission (CR) and established a correlation with clinical outcome. At diagnosis, all patients had WT1 overexpression. All patients were in morphological and genetic CR at the time of PBSC collection and before ASCT. Real-time quantitative PCR of WT1 was performed in samples of each LK, using TaqMan technology on RNA from mononucleated cells. The median WT1 transcript level in the PBSC graft (WT1-LK) of patients who relapsed was significantly higher than of those who did not relapse after transplantation (P <.0001). We defined a cut-off level of 80 WT1-LK copies/ABL 10e4 copies to discriminate between positive and negative PBSC grafts. The cut-off level was strongly associated with disease recurrence, DFS and OS. Our study represents the largest series of patients evaluating WT1 as a marker of MRD in PBSC LK products using a completely standardized real-time WT1-reverse transcriptase-PCR based assay. These data, if confirmed by prospective study, will help to determine an individual patient's adapted postremission allocation strategy.

Wilms' tumor gene 1 immunotherapy in pelvic gynecological malignancies

Pelvic gynecological malignancies account for 6% of all cancers. In the relapsed state, classical treatments are limited. There is an urgent need for new and personalized treatment. Wilms' tumor gene 1 (WT1) is the most important tumor-associated antigen. Although highly present in gynecological tumors, active immunotherapy against it is still underexplored. This review gives an insight into the importance of WT1 in pelvic gynecological malignancies and the first taken steps into the world of WT1 immunotherapy.

Homology modeling and molecular dynamics studies of Wilms' tumor gene 1 frameshift mutations in exon 7

As a transcription factor, the Wilms' tumor 1 (WT1) gene plays an important role in leukemogenesis. The impact of WT1 gene mutations has been reported in acute myeloid leukemia (AML). However, the number of available studies on the spatial configuration changes following WT1 mutation is limited. In this study, we sequenced the mutation in exon 7 of the WT1 gene in 60 children with newly diagnosed AML and the spatial configuration of WT1 with frameshift mutations in exon 7 was evaluated using the software for homology modeling and optimization of molecular dynamics. Three cases with frameshift mutations in exon 7 were identified (3/60; mutation rate, 5%). One case had a mutation that had been previously described, whereas the remaining two mutations were first described in our study. Of the three cases, one case presented with antecedent myelodysplastic syndrome (MDS) and the remaining two cases exhibited primary resistance to induction chemotherapy. The spatial configuration analysis demonstrated that the three mutations affected the spatial structure of exon 7 and even affected exon 8 compared to its wild-type. This study demonstrated that the frameshift mutation in exon 7 of the WT1 gene is a poor prognostic factor for children with AML, partly through the spatial configuration changes following frameshift mutations of WT1, which highlights the structure-based function analysis and may facilitate the elucidation of the pathogenesis underlying WT1 gene mutations.

Combinatorial molecular marker assays of WT1, survivin, and TERT at initial diagnosis of adult acute myeloid leukemia

High levels of expression of Wilms' tumor gene 1 (WT1), survivin, or telomerase reverse transcriptase (TERT) genes are introduced as leukemia-associated targets predicting clinical outcome. We prospectively investigated the leukemia-associated gene transcripts by real-time quantitative polymerase chain reaction from 151 adult patients with AML associated with the patients' clinical characteristics. The maximum levels of each gene in bone marrow were 64.4-, 8.1-, and 3.9-fold higher than those in the normal control, respectively. In contrast to the WT1 and TERT levels, survivin showed comparatively higher expression in the unfavorable cytogenetic group of patients. We found a significant difference in survivin levels between the CR and non-CR groups (P = 0.0237). TERT expression levels were higher in patients who had a greater number of peripheral blood leukemic blasts at diagnosis (P = 0.0191). Non-MRC subtypes and patients without specific mutations were the most powerful predictive factors for a better CR rate, by multivariate analyses. The lower levels of both WT1 and survivin co-expression (P = 0.0129) and both survivin + TERT co-expression (P = 0.0115) were significant factors for better OS. Besides lower initial levels of serum ferritin (P = 0.0401), lower levels of WT1 (P = 0.0438) and survivin (P = 0.0401), lower levels of both WT1 and survivin co-expression (P = 0.0031), and the three-gene combination of lower WT1 + survivin + TERT (P = 0.0454) were powerful predictive factors for better EFS. As our findings were based on a single disease entity, that is, adult AML, they suggest that the expression of these genes may be critical for the immunobiology of AML to influence the clinical outcome in various ways.