Bidirectional phonon emission in two-dimensional heterostructures triggered by ultrafast charge transfer

Photoinduced charge transfer in van der Waals heterostructures occurs on the 100 fs timescale despite weak interlayer coupling and momentum mismatch. However, little is understood about the microscopic mechanism behind this ultrafast process and the role of the lattice in mediating it. Here, using femtosecond electron diffraction, we directly visualize lattice dynamics in photoexcited heterostructures of WSe₂/WS₂ monolayers. Following the selective excitation of WSe₂, we measure the concurrent heating of both WSe₂ and WS₂ on a picosecond timescale-an observation that is not explained by phonon transport across the interface. Using first-principles calculations, we identify a fast channel involving an electronic state hybridized across the heterostructure, enabling phonon-assisted interlayer transfer of photoexcited electrons. Phonons are emitted in both layers on the femtosecond timescale via this channel, consistent with the simultaneous lattice heating observed experimentally. Taken together, our work indicates strong electron-phonon coupling via layer-hybridized electronic states-a novel route to control energy transport across atomic junctions.

Sarcopenia and change in body composition following maximal androgen suppression with abiraterone in men with castration-resistant prostate cancer

BACKGROUND

Standard medical castration reduces muscle mass. We sought to characterize body composition changes in men undergoing maximal androgen suppression with and without exogenous gluocorticoids.

METHODS

Cross-sectional areas of total fat, visceral fat and muscle were measured on serial CT scans in a post-hoc analysis of patients treated in Phase I/II trials with abiraterone followed by abiraterone and dexamethasone 0.5 mg daily. Linear mixed regression models were used to account for variations in time-on-treatment and baseline body mass index (BMI).

RESULTS

Fifty-five patients received a median of 7.5 months abiraterone followed by 5.4 months abiraterone and dexamethasone. Muscle loss was observed on single-agent abiraterone (maximal in patients with baseline BMI >30, -4.3%), but no further loss was observed after addition of dexamethasone. Loss of visceral fat was also observed on single-agent abiraterone, (baseline BMI >30 patients -19.6%). In contrast, addition of dexamethasone led to an increase in central visceral and total fat and BMI in all the patients.

INTERPRETATION

Maximal androgen suppression was associated with loss of muscle and visceral fat. Addition of low dose dexamethasone resulted in significant increases in visceral and total fat. These changes could have important quality-of-life implications for men treated with abiraterone.

Antitumour activity of docetaxel following treatment with the CYP17A1 inhibitor abiraterone: clinical evidence for cross-resistance?

BACKGROUND

Abiraterone and docetaxel are both approved treatments for men with metastatic castration-resistant prostate cancer (mCRPC). Abiraterone pre-docetaxel is currently undergoing evaluation in a phase III study. In vitro studies indicate that taxanes may act by disrupting androgen receptor signalling. We hypothesised that prior abiraterone exposure would adversely impact docetaxel efficacy.

PATIENTS AND METHODS

We retrospectively evaluated activity of docetaxel in mCRPC patients previously treated with abiraterone, using Prostate Cancer Working Group and radiological criteria.

RESULTS

Of the 54 patients treated with abiraterone, 35 subsequently received docetaxel. Docetaxel resulted in a prostate-specific antigen (PSA) decline of ≥50% in nine patients [26%, 95% confidence interval (CI) 13% to 43%], with a median time to PSA progression of 4.6 months (95% CI 4.2% to 5.9%). PSA declines ≥30% were achieved by 13 patients (37%, 95% CI 22% to 55%). The median overall survival was 12.5 months (95% CI 10.6-19.4). All patients who failed to achieve a PSA fall on abiraterone and were deemed abiraterone-refractory were also docetaxel-refractory (N = 8). In the 24 patients with radiologically evaluable disease, partial responses were reported in four patients (11%), none of whom were abiraterone-refractory.

CONCLUSION

The activity of docetaxel post-abiraterone appears lower than anticipated and no responses to docetaxel were observed in abiraterone-refractory patients.

Optical excitation of a forbidden magnetic resonance mode in a doped lutetium-iron-garnet film via the inverse Faraday effect

The effective magnetic field induced by a femtosecond pulse of circularly polarized light, via the inverse Faraday effect, is shown to excite a magnetic-dipole forbidden exchange spin resonance in a lutetium iron garnet. An external magnetic field cannot excite this mode, as the iron sublattices have the same gyromagnetic ratio and no net torque can be applied between them. However, since the sublattices have different magneto-optical susceptibilities, the inverse Faraday effect induces different effective fields on different iron sites, allowing excitation.

Phase II, two-stage, single-arm trial of the histone deacetylase inhibitor (HDACi) romidepsin in metastatic castration-resistant prostate cancer (CRPC)

BACKGROUND

Histone deacetylase blockade can promote heat shock protein 90 (HSP90) acetylation, abrogating androgen receptor signaling. A phase II trial of the histone deacetylase inhibitor (HDACi) romidepsin was conducted in patients with progressing, metastatic, castration-resistant prostate cancer (CRPC).

PATIENTS AND METHODS

A dose of 13 mg/m(2) was administered i.v. over 4 h on days 1, 8 and 15 every 28 days. The primary end point was rate of disease control defined as no evidence of radiological progression at 6 months. A sample size of 16 assessable patients in stage 1 and nine assessable patients in stage 2 was selected; progression to stage 2 required one or more patients with disease control in stage 1 (H(o) = 0.10, H(a) = 0.30; alpha and beta = 0.10).

RESULTS

Thirty-five patients were enrolled. Two patients achieved a confirmed radiological partial response (RECIST) lasting > or = 6 months, along with a confirmed prostate-specific antigen decline of > or = 50%. Eleven patients experienced toxicity necessitating early discontinuation. The commonest adverse events were nausea (30 patients; 85.7%), fatigue (28 patients; 80.0%), vomiting (23 patients; 65.7%) and anorexia (20 patients; 57.1%). There was no significant cardiac toxicity.

CONCLUSIONS

At the dose and schedule selected, romidepsin demonstrated minimal antitumor activity in chemonaive patients with CRPC. Further studies of improved HDACi, alone and in combination with other therapies, should nevertheless be investigated.

Circulating tumour cell (CTC) counts as intermediate end points in castration-resistant prostate cancer (CRPC): a single-centre experience

BACKGROUND

The purpose of this study was to evaluate the association of circulating tumour cell (CTC) counts, before and after commencing treatment, with overall survival (OS) in patients with castration-resistant prostate cancer (CRPC).

EXPERIMENTAL DESIGN

A 7.5 ml of blood was collected before and after treatment in 119 patients with CRPC. CTCs were enumerated using the CellSearchSystem.

RESULTS

Higher CTC counts associated with baseline characteristics portending aggressive disease. Multivariate analyses indicated that a CTC >or=5 was an independent prognostic factor at all time points evaluated. Patients with baseline CTC >or=5 had shorter OS than those with <5 [median OS 19.5 versus >30 months, hazard ratio (HR) 3.25, P=0.012]; patients with CTC >50 had a poorer OS than those with CTCs 5-50 (median OS 6.3 versus 21.1 months, HR 4.1, P<0.001). Patients whose CTC counts reduced from >or=5 at baseline to <5 following treatment had a better OS compared with those who did not. CTC counts showed a similar, but earlier and independent, ability to time to disease progression to predict OS.

CONCLUSION

CTC counts predict OS and provide independent prognostic information to time to disease progression; CTC dynamics following therapy need to be evaluated as an intermediate end point of outcome in randomised phase III trials.