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Acute myeloid leukemia (AML) is a heterogeneous, highly malignant disease of the bone marrow. After decades of slow progress, recent years saw a surge of novel agents for its treatment. The most recent advancement is the registration of the Bcl-2 inhibitor ventoclax in combination with a hypomethylating agent (HMA) in the US and Europe for AML patients not eligible for intensive chemotherapy. Treatment of newly diagnosed AML patients with this combination results in remission rates that so far could only be achieved with intensive treatment. However, not all AML patients respond equally well, and some patients relapse early, while other patients experience longer periods of complete remission. A hallmark of AML is its remarkable genetic, molecular and clinical heterogeneity. Here, we review the current knowledge about molecular features of AML that help estimate the probability of response to venetoclax-containing therapies. In contrast to other newly developed AML therapies that target specific recurrent molecular alterations, it seems so far that responses are not specific for a certain subgroup. One exception is spliceosome mutations, where good response has been observed in clinical trials with venetoclax/azacitidine. These mutations are rather associated with a more unfavorable outcome with chemotherapy. In summary, venetoclax in combination with hypomethylating agents represents a significant novel option for AML patients with various molecular aberrations. Mechanisms of primary and secondary resistance seem to overlap with those towards chemotherapy.

Acute myeloid leukemia (AML) is an aggressive blood cancer with a poor prognosis. We report a comprehensive proteogenomic analysis of bone marrow biopsies from 252 uniformly treated AML patients to elucidate the molecular pathophysiology of AML in order to inform future diagnostic and therapeutic approaches. In addition to in-depth quantitative proteomics, our analysis includes cytogenetic profiling and DNA/RNA sequencing. We identify five proteomic AML subtypes, each reflecting specific biological features spanning genomic boundaries. Two of these proteomic subtypes correlate with patient outcome, but none is exclusively associated with specific genomic aberrations. Remarkably, one subtype (Mito-AML), which is captured only in the proteome, is characterized by high expression of mitochondrial proteins and confers poor outcome, with reduced remission rate and shorter overall survival on treatment with intensive induction chemotherapy. Functional analyses reveal that Mito-AML is metabolically wired toward stronger complex I-dependent respiration and is more responsive to treatment with the BCL2 inhibitor venetoclax.

The standard technique for investigating adrenergic effects on heart function is perfusion with pharmaceutical agonists, which does not provide high temporal or spatial precision. Herein we demonstrate that the light sensitive Gs-protein coupled receptor JellyOp enables optogenetic stimulation of Gs-signaling in cardiomyocytes and the whole heart. Illumination of transgenic embryonic stem cell-derived cardiomyocytes or of the right atrium of mice expressing JellyOp elevates cAMP levels and instantaneously accelerates spontaneous beating rates similar to pharmacological β-adrenergic stimulation. Light application to the dorsal left atrium instead leads to supraventricular extrabeats, indicating adverse effects of localized Gs-signaling. In isolated ventricular cardiomyocytes from JellyOp mice, we find increased Ca2+ currents, fractional cell shortening and relaxation rates after illumination enabling the analysis of differential Gs-signaling with high temporal precision. Thus, JellyOp expression allows localized and time-restricted Gs stimulation and will provide mechanistic insights into different effects of site-specific, long-lasting and pulsatile Gs activation., Studying adrenergic signalling in the heart requires perfusion with receptor agonists, which lacks cell specificity and spatiotemporal control. Here the authors use the light sensitive G-coupled receptor JellyOp to optogenetically control Gs-signaling in cardiomyocytes and intact hearts with high spatiotemporal precision.

Stimulation of GS-protein coupled receptors leads to an increase of the second messenger cyclic adenosine monophosphate (cAMP). In cardiomyocytes the GS-signaling cascade is involved in positive regulation of chronotropy and contractility but chronic GS stimulation can also induce cardiac hypertrophy or arrhythmia.Experimentally, the GS-signaling cascade can be activated by s-receptor agonists but diffusion of drugs does not allow the precise control of location and timing. To overcome these limitations we used the optogenetic protein JellyOp, a directly GS-coupled, light-sensitive receptor (Bailes et al. PloS One, 2012) to activate GS-signaling by light.Illumination of JellyOp expressing HEK 293 cells resulted in elevation of cAMP levels without detectable dark activity. Cardiomyocytes were differentiated within embryoid bodies (EBs) from transgenic mouse embryonic stem cells that express JellyOp under control of the ubiquitous chicken s-actin promoter. Spontaneously beating EBs were analyzed at day 13 of differentiation by infrared video microscopy. Brief illumination (20 sec, 470 nm, 166.7 nW/mm2) increased beating frequency to 1239±349% of baseline (n=3) which returned to baseline after termination of illumination. The lowest effective light intensity was of 9.1 nW/mm2 resulting in frequency acceleration to 428±131% of baseline and the shortest effective illumination was 1 sec. Similar to dose-response-curves of receptor agonists, light-induced frequency acceleration showed a sigmoid dependence on light-intensity with a half maximal light intensity of 33.5 nW/mm2. Direct comparison showed that the rate of frequency increment was much faster using illumination (13.9±3.1%/s) than using perfusion with the s-receptor agonist isoprenaline (2.7±1.5%/s) but both stimulations led to a similar response in frequency elevation.In summary optogenetic JellyOp activation in cardiomyocytes enables the stimulation of the GS-signaling pathway with high temporal precision and will be useful to investigate temporal and site-specific effects of physiological and pathophysiological GS-activation.