Frailty in Older Adults With Multiple Myeloma: A Study of US Veterans.

PURPOSE: Age-associated cumulative decline across physiologic systems results in a diminished resistance to stressors, including cancer and its treatment, creating a vulnerable state known as frailty. Frailty is associated with increased risk of adverse outcomes in patients with cancer. Identification of frailty in administrative data can allow for assessment of prognosis and facilitate control for confounding variables. The purpose of this study was to assess frailty from claims-based data using the accumulation of deficits approach in veterans with multiple myeloma (MM). METHODS: From the Veterans Administration Central Cancer Registry, we identified patients who were diagnosed with MM between 1999 and 2014. Using the accumulation of deficits approach, we calculated a Frailty Index (FI) using 31 health-associated deficits and categorized scores into five groups: nonfrail (FI, 0 to 0.1), prefrail (FI, 0.11 to 0.20), mild frailty (FI, 0.21 to 0.30), moderate frailty (FI, 0.31 to 0.40), and severe frailty (FI, > 0.4). We used Cox proportional hazards regression analysis to assess association between FI score and mortality while adjusting for potential confounders. RESULTS: We calculated an FI for 3,807 veterans age 65 years or older. Among the cohort, 28.7% were classified as nonfrail, 41.3% prefrail, 21.6% mildly frail, 6.6% moderately frail, and 1.7% severely frail. Frailty was strongly associated with mortality independent of age, race, MM treatment, body mass index, or statin use. Higher FI score was associated with higher mortality with hazard ratios of 1.33 (95% CI, 1.21 to 1.47), 1.97 (95% CI, 1.70 to 2.20), 2.86 (95% CI, 2.45 to 3.34), and 3.22 (95% CI, 2.46 to 4.22) for prefrail, mildly frail, moderately frail, and severely frail, respectively. CONCLUSION: Frailty status is a significant predictor of mortality in older veterans with MM. Assessment of frailty status using the readily available electronic medical records data in administrative data allows for assessment of prognosis.

Initial experience with combined BRAF and MEK inhibition with stereotactic radiosurgery for BRAF mutant melanoma brain metastases.

The combined use of the BRAF inhibitor dabrafenib and MEK inhibitor trametinib has been found to improve survival over dabrafenib alone. The management of melanoma brain metastases continues to present challenges. In this study, we report our initial experience in the management of melanoma brain metastases with stereotactic radiosurgery (SRS) with the use of BRAF and MEK inhibitors. We identified six patients treated with SRS for 17 brain metastases within 3 months of BRAF and MEK inhibitor administration. The median planning target volume was 0.42 cm (range: 0.078-2.08 cm). The median treatment dose was 21 Gy (range 18-24 Gy). The median follow-up of all lesions from SRS was 10.6 months (range 5.8-28.5 months). One lesion was found to undergo local failure 21.7 months following SRS treatment. The median overall survival was 20.0 months (range 6.1-31.8 months) from the time of SRS treatment and 23.1 months (range: 12.1-30.9 months) from the date of BRAFi and MEKi administration. There was no evidence of increased nor unexpected toxicity with the two modalities combined. In this initial experience of melanoma brain metastases treated with BRAF and MEK inhibition with SRS, we find the two modalities can be combined safely. These outcomes should be assessed further in prospective evaluations.

Phosphorylation of cardiac Myosin-binding protein-C is a critical mediator of diastolic function.

BACKGROUND: Heart failure (HF) with preserved ejection fraction (HFpEF) accounts for ≈50% of all cases of HF and currently has no effective treatment. Diastolic dysfunction underlies HFpEF; therefore, elucidation of the mechanisms that mediate relaxation can provide new potential targets for treatment. Cardiac myosin-binding protein-C (cMyBP-C) is a thick filament protein that modulates cross-bridge cycling rates via alterations in its phosphorylation status. Thus, we hypothesize that phosphorylated cMyBP-C accelerates the rate of cross-bridge detachment, thereby enhancing relaxation to mediate diastolic function. METHODS AND RESULTS: We compared mouse models expressing phosphorylation-deficient cMyBP-C(S273A/S282A/S302A)-cMyBP-C(t3SA), phosphomimetic cMyBP-C(S273D/S282D/S302D)-cMyBP-C(t3SD), and wild-type-control cMyBP-C(tWT) to elucidate the functional effects of cMyBP-C phosphorylation. Decreased voluntary running distances, increased lung/body weight ratios, and increased brain natriuretic peptide levels in cMyBP-C(t3SA) mice demonstrate that phosphorylation deficiency is associated with signs of HF. Echocardiography (ejection fraction and myocardial relaxation velocity) and pressure/volume measurements (-dP/dtmin, pressure decay time constant τ-Glantz, and passive filling stiffness) show that cMyBP-C phosphorylation enhances myocardial relaxation in cMyBP-C(t3SD) mice, whereas deficient cMyBP-C phosphorylation causes diastolic dysfunction with HFpEF in cMyBP-C(t3SA) mice. Simultaneous force and [Ca(2+)]i measurements on intact papillary muscles show that enhancement of relaxation in cMyBP-C(t3SD) mice and impairment of relaxation in cMyBP-C(t3SA) mice are not because of altered [Ca(2+)]i handling, implicating that altered cross-bridge detachment rates mediate these changes in relaxation rates. CONCLUSIONS: cMyBP-C phosphorylation enhances relaxation, whereas deficient phosphorylation causes diastolic dysfunction and phenotypes resembling HFpEF. Thus, cMyBP-C is a potential target for treatment of HFpEF.

Novel control of cardiac myofilament response to calcium by S-glutathionylation at specific sites of myosin binding protein C.

Our previous studies demonstrated a relation between glutathionylation of cardiac myosin binding protein C (cMyBP-C) and diastolic dysfunction in a hypertensive mouse model stressed by treatment with salt, deoxycorticosterone acetate, and unilateral nephrectomy. Although these results strongly indicated an important role for S-glutathionylation of myosin binding protein C as a modifier of myofilament function, indirect effects of other post-translational modifications may have occurred. Moreover, we did not determine the sites of thiol modification by glutathionylation. To address these issues, we developed an in vitro method to mimic the in situ S-glutathionylation of myofilament proteins and determined direct functional effects and sites of oxidative modification employing Western blotting and mass spectrometry. We induced glutathionylation in vitro by treatment of isolated myofibrils and detergent extracted fiber bundles (skinned fibers) with oxidized glutathione (GSSG). Immuno-blotting results revealed increased glutathionylation with GSSG treatment of a protein band around 140 kDa. Using tandem mass spectrometry, we identified the 140 kDa band as cMyBP-C and determined the sites of glutathionylation to be at cysteines 655, 479, and 627. Determination of the relation between Ca(2+)-activation of myofibrillar acto-myosin ATPase rate demonstrated an increased Ca(2+)-sensitivity induced by the S-glutathionylation. Force generating skinned fiber bundles also showed an increase in Ca-sensitivity when treated with oxidized glutathione, which was reversed with the reducing agent, dithiothreitol (DTT). Our data demonstrate that a specific and direct effect of S-glutathionylation of myosin binding protein C is a significant increase in myofilament Ca(2+)-sensitivity. Our data also provide new insights into the functional significance of oxidative modification of myosin binding protein C and the potential role of domains not previously considered to be functionally significant as controllers of myofilament Ca(2+)-responsiveness and dynamics.

Tetrahydrobiopterin improves diastolic dysfunction by reversing changes in myofilament properties.

Despite the increasing prevalence of heart failure with preserved left ventricular function, there are no specific treatments, partially because the mechanism of impaired relaxation is incompletely understood. Evidence indicates that cardiac relaxation may depend on nitric oxide (NO), generated by NO synthase (NOS) requiring the co-factor tetrahydrobiopterin (BH(4)). Recently, we reported that hypertension-induced diastolic dysfunction was accompanied by cardiac BH(4) depletion, NOS uncoupling, a depression in myofilament cross-bridge kinetics, and S-glutathionylation of myosin binding protein C (MyBP-C). We hypothesized that the mechanism by which BH(4) ameliorates diastolic dysfunction is by preventing glutathionylation of MyBP-C and thus reversing changes of myofilament properties that occur during diastolic dysfunction. We used the deoxycorticosterone acetate (DOCA)-salt mouse model, which demonstrates mild hypertension, myocardial oxidative stress, and diastolic dysfunction. Mice were divided into two groups that received control diet and two groups that received BH(4) supplement for 7days after developing diastolic dysfunction at post-operative day 11. Mice were assessed by echocardiography. Left ventricular papillary detergent-extracted fiber bundles were isolated for simultaneous determination of force and ATPase activity. Sarcomeric protein glutathionylation was assessed by immunoblotting. DOCA-salt mice exhibited diastolic dysfunction that was reversed after BH(4) treatment. Diastolic sarcomere length (DOCA-salt 1.70±0.01 vs. DOCA-salt+BH(4) 1.77±0.01µm, P<0.001) and relengthening (relaxation constant, τ, DOCA-salt 0.28±0.02 vs. DOCA-salt+BH(4) 0.08±0.01, P<0.001) were also restored to control by BH(4) treatment. pCa(50) for tension increased in DOCA-salt compared to sham but reverted to sham levels after BH(4) treatment. Maximum ATPase rate and tension cost (ΔATPase/ΔTension) decreased in DOCA-salt compared to sham, but increased after BH(4) treatment. Cardiac MyBP-C glutathionylation increased in DOCA-salt compared to sham, but decreased with BH(4) treatment. MyBP-C glutathionylation correlated with the presence of diastolic dysfunction. Our results suggest that by depressing S-glutathionylation of MyBP-C, BH(4) ameliorates diastolic dysfunction by reversing a decrease in cross-bridge turnover kinetics. These data provide evidence for modulation of cardiac relaxation by post-translational modification of myofilament proteins.

Ranolazine improves cardiac diastolic dysfunction through modulation of myofilament calcium sensitivity.

RATIONALE: Previously, we demonstrated that a deoxycorticosterone acetate (DOCA)-salt hypertensive mouse model produces cardiac oxidative stress and diastolic dysfunction with preserved systolic function. Oxidative stress has been shown to increase late inward sodium current (I(Na)), reducing the net cytosolic Ca(2+) efflux. OBJECTIVE: Oxidative stress in the DOCA-salt model may increase late I(Na), resulting in diastolic dysfunction amenable to treatment with ranolazine. METHODS AND RESULTS: Echocardiography detected evidence of diastolic dysfunction in hypertensive mice that improved after treatment with ranolazine (E/E':sham, 31.9 ± 2.8, sham+ranolazine, 30.2 ± 1.9, DOCA-salt, 41.8 ± 2.6, and DOCA-salt+ranolazine, 31.9 ± 2.6; P=0.018). The end-diastolic pressure-volume relationship slope was elevated in DOCA-salt mice, improving to sham levels with treatment (sham, 0.16 ± 0.01 versus sham+ranolazine, 0.18 ± 0.01 versus DOCA-salt, 0.23 ± 0.2 versus DOCA-salt+ranolazine, 0.17 ± 0.0 1 mm Hg/L; P<0.005). DOCA-salt myocytes demonstrated impaired relaxation, τ, improving with ranolazine (DOCA-salt, 0.18 ± 0.02, DOCA-salt+ranolazine, 0.13 ± 0.01, sham, 0.11 ± 0.01, sham+ranolazine, 0.09 ± 0.02 seconds; P=0.0004). Neither late I(Na) nor the Ca(2+) transients were different from sham myocytes. Detergent extracted fiber bundles from DOCA-salt hearts demonstrated increased myofilament response to Ca(2+) with glutathionylation of myosin binding protein C. Treatment with ranolazine ameliorated the Ca(2+) response and cross-bridge kinetics. CONCLUSIONS: Diastolic dysfunction could be reversed by ranolazine, probably resulting from a direct effect on myofilaments, indicating that cardiac oxidative stress may mediate diastolic dysfunction through altering the contractile apparatus.

p21-activated kinase improves cardiac contractility during ischemia-reperfusion concomitant with changes in troponin-T and myosin light chain 2 phosphorylation.

p21-activated kinase 1 (Pak1) is a serine/threonine kinase that activates protein phosphatase 2a, resulting in the dephosphorylation of cardiac proteins and increased myofilament Ca(2+) sensitivity. Emerging evidence indirectly indicates a role for Pak1 in ischemia-reperfusion (I/R), but direct evidence is lacking. We hypothesize that activation of the Pak1 signaling pathway is a cardioprotective mechanism that prevents or reverses the detrimental effects of ischemic injury by inducing posttranslational modifications in myofilament proteins that ultimately improve cardiac contractility following ischemic insult. In the present study, we subjected ex vivo hearts from wild-type (WT) and Pak1-knockout (KO) mice to 20 min of global cardiac ischemia followed by 30 min of reperfusion. In the absence of Pak1, there was an exacerbation of the increased end-diastolic pressure and reduced left ventricular developed pressure occurring after I/R injury. ProQ analysis revealed an increase in troponin-T phosphorylation at baseline in Pak1-KO hearts compared with WT. Significantly decreased myosin light chain 2 (MLC2) phosphorylation in Pak1-KO hearts compared with WT after I/R injury was confirmed by Western immunoblotting. These data indicate that Pak1-KO hearts have reduced recovery of myocardial performance after global I/R injury concomitant with changes in troponin-T and MLC2 phosphorylation. Finally, a protein-protein association between Pak1 and MLC2, and Pak1 and troponin-T, was determined by coimmunoprecipitation. Thus, results of our study provide a basis for targeting a novel pathway, including Pak1, in the therapies for patients with ischemic events.