Imaging Intensity and Survival Outcomes in High-Risk Resected Melanoma Treated by Systemic Therapy at Recurrence.

BACKGROUND: Intensive imaging in melanoma remains controversial because its survival impact is unknown. We investigated the impact of imaging intensity on the rates of asymptomatic surveillance-detected recurrence (ASDR) and subsequent treatment outcomes in patients with access to immune checkpoint inhibitors (ICIs) and targeted therapy (TT). METHODS: Patients with resected malignant melanoma undergoing imaging surveillance at a single center between 2006 and 2016 were identified. Surveillance and recurrence characteristics (imaging, symptom, treatment, and survival data) were retrospectively collected. Univariate (t test, Chi square test) and multivariate Cox regression analyses were conducted. RESULTS: Of 353 high-risk melanoma patients (stage IIB, 24%; IIC, 19%; IIIA, 27%; IIIB, 16%; IIIC, 14%), 71 (45%) had ASDR and 88 (55%) had symptomatic recurrence (SR). Shorter imaging intervals identified more ASDR (57%, 0-6 months; 34%, 6-12 months; 33%, > 12 months; p = 0.03). ASDR had better prognostic factors than SR [fewer than three metastatic sites (43 vs. 21%, p = 0.003), normal lactate dehydrogenase (LDH; 53 vs. 38%, p = 0.09), brain metastases (11 vs. 40%, p < 0.001)] and received more systemic treatment (72 vs. 49%, p = 0.003; ICIs 55 vs. 31%, p = 0.002; TT 8 vs. 13%, p = 0.41). ASDR had better survival outcomes on ICI treatment (2-year OS, 56 vs. 31%, p < 0.001). Median OS from surveillance start was 39.6 vs. 22.8 months (p < 0.001). ASDR was independently associated with survival (hazard ratio 0.47, 95% confidence interval 0.29-0.78, p = 0.003), adjusting for stage, sex, age, disease burden, LDH, era of recurrence, brain metastases, and ICI/TT treatment. CONCLUSIONS: These real-world data support further study on intensified imaging surveillance protocols for high-risk resected melanoma, as ASDR was associated with superior survival outcomes from ICI therapy.

Correction to: Imaging Intensity and Survival Outcomes in High-Risk Resected Melanoma Treated by Systemic Therapy at Recurrence.

In the original article, the survival curves are missing in Fig. 1c, d.

Induction of Pax3 gene expression impedes cardiac differentiation.

Cell-based therapies using pluripotent stem cells hold great promise as regenerative approaches to treat many types of diseases. Nevertheless many challenges remain and, perhaps foremost, is the issue of how to direct and enhance the specification and differentiation of a desired cell type for potential therapeutics. We have examined the molecular basis for the inverse correlation of cardiac and skeletal myogenesis in small molecule-enhanced stem cell differentiation. Our study shows that activation of premyogenic factor Pax3 coincides with inhibiting gene expression of early cardiac factor GATA4. Interestingly, the inhibitory effect of small molecules on cardiac differentiation depends on the function of Pax3, but not the mesoderm factor Meox1. Thus Pax3 is an inhibitor of cardiac differentiation in lineage specification. Our studies reveal the dual roles of Pax3 in stem cell fate determinations and provide new molecular insights into small molecule-enhanced lineage specification.

Analysis of p300 occupancy at the early stage of stem cell differentiation by chromatin immunoprecipitation.

Chromatin immunoprecipitation (ChIP) is an invaluable method to study the specific interaction of regulatory proteins with genomic DNA. Since its first development, it has been modified extensively to make it applicable to many different cell types and experimental systems. The cross-linking of regulatory proteins to genomic DNA requires monolayer cells or single cell suspensions. Here, we describe a ChIP protocol using embryoid bodies formed at the early stage differentiation of pluripotent stem cells, which we have used to determine long-range p300-dependent regulatory elements of myogenic-specific genes.

Regulation of Myf5 Early Enhancer by Histone Acetyltransferase p300 during Stem Cell Differentiation.

Skeletal myogenesis is an intricate process coordinated temporally by multiple myogenic regulatory factors (MRF) including Myf5, which is the first MRF expressed and marks the commitment of skeletal muscle lineage. The expression of Myf5 gene during early embryogenesis is controlled by a set of enhancer elements, and requires the histone acetyltransferase (HAT) activity of transcriptional coactivator p300. However, it is unclear as to how different regulatory signals converge at enhancer elements to regulate early Myf5 gene expression, and if p300 is directly involved. We show here that p300 associates with the Myf5 early enhancer at the early stage of stem cell differentiation, and its HAT activity is important for the recruitment of ß-catenin to this early enhancer. In addition, histone H3-K27 acetylation, but not H3-K9/14, is intimately connected to the p300 HAT activity. Thus, p300 is directly involved in the regulation of the Myf5 early enhancer, and is important for specific histone acetylation and transcription factor recruitment. This connection of p300 HAT activity with H3-K27 acetylation and ß-catenin signalling during myogenic differentiation in vitro offers a molecular insight into the enhancer-elements participation observed in embryonic development. In addition, pluripotent stem cell differentiation is a valuable system to dissect the signal-dependent regulation of specific enhancer element during cell fate determinations.

Contribution of retinoid X receptor signaling to the specification of skeletal muscle lineage.

Pluripotent stem cells possess a tremendous potential for the treatment of many diseases because of their capacity to differentiate into a variety of cell lineages. However, they provide little promise for muscle-related diseases, mainly because of the lack of small molecule inducers to efficiently direct myogenic conversion. Retinoic acid, acting through the retinoic acid receptor (RAR) and retinoid X receptor (RXR), affects stem cell fate determination in a concentration-dependent manner, but it only has a modest efficacy on the commitment of ES cells into skeletal muscle lineage. The RXR is very important for embryonic development but is generally considered to act as a silent partner of RAR in a non-permissive mode. In this study, we have examined whether activation of the RXR by rexinoid or RXR-specific signaling play a role in the specification of stem cells into muscle lineage. Our findings demonstrate that mouse ES cells generate skeletal myocytes effectively upon treatment with rexinoid at the early stage of differentiation and that on a molecular level, rexinoid-enhanced myogenesis simulates the sequential events observed in vivo. Moreover, RXR-mediated myogenic conversion requires the function of ß-catenin but not RAR. Our studies establish the feasibility of applying the RXR agonist in cell-based therapies to treat muscle-related diseases. The aptitude of mouse ES cells to generate skeletal myocytes following rexinoid induction also provides a model system to study the convergence of different signaling pathways in myogenesis.