Background The National Cancer Institute of Canada Clinical Trials Group CO.17 study showed that patients with advanced colorectal cancer had improved overall survival when cetuximab, an epidermal ...growth factor receptor–targeting antibody, was given in addition to best supportive care. We conducted a cost-effectiveness analysis using prospectively collected resource utilization and health utility data for patients in the CO.17 study who received cetuximab plus best supportive care (N = 283) or best supportive care alone (N = 274). Methods Direct medical resource utilization data were collected, including medications, physician visits, toxicity management, blood products, emergency department visits, and hospitalizations. Mean survival times for the study arms were calculated for the entire population and for the subset of patients with wild-type KRAS tumors over an 18- to 19-month period. All costs were presented in 2007 Canadian dollars. One-way and probabilistic sensitivity analysis was used to determine the robustness of the results. Cost-effectiveness acceptability curves were determined. The 95% confidence intervals (CIs) for the incremental cost-effectiveness ratios and the incremental cost–utility ratios were estimated by use of a nonparametric bootstrapping method (with 1000 iterations). Results For the entire study population, the mean improvement in overall and quality-adjusted survival with cetuximab was 0.12 years and 0.08 quality-adjusted life-years (QALYs), respectively. The incremental cost with cetuximab compared with best supportive care was $23 969. The incremental cost-effectiveness ratio was $199 742 per life-year gained (95% CI = $125 973 to $652 492 per life-year gained) and the incremental cost–utility ratio was $299 613 per QALY gained (95% CI = $187 440 to $898 201 per QALY gained). For patients with wild-type KRAS tumors, the incremental cost with cetuximab was $33 617 and mean gains in overall and quality-adjusted survival were 0.28 years and 0.18 QALYs, respectively. The incremental cost-effectiveness ratio was $120 061 per life-year gained (95% CI = $88 679 to $207 075 per life-year gained) and the incremental cost–utility ratio was $186 761 per QALY gained (95% CI = $130 326 to $334 940 per QALY gained). In a sensitivity analysis, cetuximab cost and patient survival were the only variables that influenced cost-effectiveness. Conclusions The incremental cost-effectiveness ratio of cetuximab over best supportive care alone in unselected advanced colorectal cancer patients is high and sensitive to drug cost. Incremental cost-effectiveness ratios were lower when the analysis was limited to patients with wild-type KRAS tumors.
Aims. Recent observations of core-collapse supernovae (SNe) suggest aspherical explosions. Globally, aspherical structures in SN explosions are thought to encode information regarding the underlying ...explosion mechanism. However, the exact explosion geometries from the inner cores to the outer envelopes are poorly understood. Methods. Here, we present photometric, spectroscopic, and polarimetric observations of the Type IIP SN 2021yja and discuss its explosion geometry in comparison to those of other Type IIP SNe that show large-scale aspherical structures in their hydrogen envelopes (SNe 2012aw, 2013ej and 2017gmr). Results. During the plateau phase, SNe 2012aw and 2021yja exhibit high continuum polarization characterized by two components with perpendicular polarization angles. This behavior can be interpreted as being due to a bipolar explosion, where the SN ejecta is composed of a polar (energetic) component and an equatorial (bulk) component. In such a bipolar explosion, an aspherical axis created by the polar ejecta would dominate at early phases, while the perpendicular axis along the equatorial ejecta would emerge at late phases after the photosphere in the polar ejecta has receded. Our interpretation of the explosions in SNe 2012aw and 2021yja as bipolar is also supported by other observational properties, including the time evolution of the line velocities and the line shapes in the nebular spectra. The polarization of other Type IIP SNe that show large-scale aspherical structures in the hydrogen envelope (SNe 2013ej and 2017gmr) is also consistent with the bipolar-explosion scenario, although this is not conclusive.
ABSTRACT
We present analysis of comprehensive radio observations of the black hole V404 Cyg during its 2015 outburst. These data represent the best ever coverage of jet production and particle ...acceleration from any black hole. We report for the first time a clear and near-linear flux–rms correlation in the radio flux densities. Investigation of individual flares reveals in nearly all cases the peak corresponds to the transition from optically thick to thin to synchrotron emission, but an extended phase of particle acceleration is required in contrast to simple impulsive injection models. The largest radio flare is preceded by a phase of optical oscillations and followed one day later by a smaller but optically thin flare, likely due to ejecta interacting with the interstellar medium. Comparing the radio emission to contemporaneous X-ray and optical data, we find that the X-ray and radio measurements are correlated on all time-scales from seconds to one day. Correlation with the optical flux densities is weak at short time-scales, but becomes significant on time-scales greater than a few hours. We evaluate the physical conditions (size, magnetic field, and internal energy) associated with 86 individual radio flares, which in turn allows us to place a lower limit on the kinetic feedback over the 15 d of intense activity. If this energy was deposited locally to the source, as implied by the failure to detect jets on angular scales larger than milliarcsec, then we predict that a nova-like shell could have been formed.
Context.
Exoplanets with orbital periods of less than one day are known as ultra-short period (USP) planets. They are relatively rare products of planetary formation and evolution processes, but ...especially favourable for characterisation with current planet detection methods. At the time of writing, 125 USP planets have already been confirmed.
Aims.
Our aim is to validate the planetary nature of two new transiting planet candidates around M dwarfs announced by the NASA Transiting Exoplanet Survey Satellite (TESS), registered as TESS Objects of Interest (TOIs) TOI-1442.01 and TOI-2445.01.
Methods.
We used TESS data, ground-based photometric light curves, and Subaru/IRD spectrograph radial velocity (RV) measurements to validate both planetary candidates and to establish their physical properties.
Results.
TOI-1442 bis a validated exoplanet with an orbital period of
P
= 0.4090682 ± 0.0000004 day, a radius of
R
p
= 1.15 ± 0.06
R
⊕
, and equilibrium temperature of
T
p,eq
= 1357
−42
+49
K. TOI-2445 b is also validated with an orbital period of
P
= 0.3711286 ± 0.0000004 day, a radius of
R
p
= 1.33 ± 0.09
R
⊕
, and equilibrium temperature of
T
p,eq
= 1330
−56
+61
K. Their physical properties align with current empirical trends and formation theories of USP planets. Based on the RV measurements, we set 3
σ
upper mass limits of 8
M
⊕
and 20
M
⊕
, thus confirming the non-stellar, sub-Jovian nature of both transiting objects. More RV measurements will be needed to constrain the planetary masses and mean densities, and the predicted presence of outer planetary companions. These targets extend the small sample of USP planets orbiting around M dwarfs up to 21 members. They are also among the 20 most suitable terrestrial planets for atmospheric characterisation via secondary eclipse with the
James Webb
Space Telescope, according to a widespread emission spectroscopy metric.
Context.
The NASA space telescope TESS is currently in the extended mission of its all-sky search for new transiting planets. Of the thousands of candidates that TESS is expected to deliver, ...transiting planets orbiting nearby M dwarfs are particularly interesting targets since they provide a great opportunity to characterize their atmospheres by transmission spectroscopy.
Aims.
We aim to validate and characterize the new sub-Neptune-sized planet candidate TOI-2136.01 orbiting a nearby M dwarf (
d
= 33.36 ± 0.02pc,
T
eff
= 3373 ± 108 K) with an orbital period of 7.852 days.
Methods.
We use TESS data, ground-based multicolor photometry, and radial velocity measurements with the InfraRed Doppler (IRD) instrument on the Subaru Telescope to validate the planetary nature of TOI-2136.01, and estimate the stellar and planetary parameters. We also conduct high-resolution transmission spectroscopy to search for helium in its atmosphere.
Results.
We confirm that TOI-2136.01 (now named TOI-2136b) is a bona fide planet with a planetary radius of
R
p
= 2.20 ± 0.07
R
⊕
and a mass of
M
p
= 4.7
−2.6
+3.1
M
⊕
. We also search for helium 10830 Å absorption lines and place an upper limit on the equivalent width of <7.8 mÅ and on the absorption signal of <1.44% with 95% confidence.
Conclusions.
TOI-2136b is a sub-Neptune transiting a nearby and bright star (
J
= 10.8 mag), and is a potentially hycean planet, which is a new class of habitable planets with large oceans under a H
2
-rich atmosphere, making it an excellent target for atmospheric studies to understand the formation, evolution, and habitability of the small planets.
TOI-1416 (BD+42 2504, HIP 70705) is a
V
=10 late G- or early K-type dwarf star. TESS detected transits in its Sectors 16, 23, and 50 with a depth of about 455 ppm and a period of 1.07 days. Radial ...velocities (RVs) confirm the presence of the transiting planet TOI-1416
b
, which has a mass of 3.48 ± 0.47
M
⊕
and a radius of 1.62 ± 0.08
R
⊕
, implying a slightly sub-Earth density of 4.50
−0.83
+0.99
g cm
−3
. The RV data also further indicate a tentative planet,
c
, with a period of 27.4 or 29.5 days, whose nature cannot be verified due to strong suspicions of contamination by a signal related to the Moon’s synodic period of 29.53 days. The nearly ultra-short-period planet TOI-1416
b
is a typical representative of a short-period and hot (
T
eq
≈ 1570 K) super-Earth-like planet. A planet model of an interior of molten magma containing a significant fraction of dissolved water provides a plausible explanation for its composition, and its atmosphere could be suitable for transmission spectroscopy with JWST. The position of TOI-1416
b
within the radius-period distribution corroborates the idea that planets with periods of less than one day do not form any special group. It instead implies that ultra-short-period planets belong to a continuous distribution of super-Earth-like planets with periods ranging from the shortest known ones up to ≈30 days; their period-radius distribution is delimited against larger radii by the Neptune Desert and by the period-radius valley that separates super-Earths from sub-Neptune planets. In the abundance of small, short-periodic planets, a notable plateau has emerged between periods of 0.6–1.4 days, which is compatible with the low-eccentricity formation channel. For the Neptune Desert, its lower limits required a revision due to the increasing population of short-period planets; for periods shorter then 2 days, we establish a radius of 1.6
R
⊕
and a mass of 0.028
M
jup
(corresponding to 8.9
M
⊕
) as the desert’s lower limits. We also provide corresponding limits to the Neptune Desert against the planets’ insolation and effective temperatures.
ABSTRACT
Accurate physical parameters of exoplanet systems are essential for further exploration of planetary internal structure, atmospheres, and formation history. We aim to use simultaneous ...multicolour transit photometry to improve the estimation of transit parameters, to search for transit timing variations (TTVs), and to establish which of our targets should be prioritized for follow-up transmission spectroscopy. We performed time series photometric observations of 12 transits for the hot Jupiters HAT-P-19b, HAT-P-51b, HAT-P-55b, and HAT-P-65b using the simultaneous four-colour camera MuSCAT2 on the Telescopio Carlos Sánchez. We collected 56 additional transit light curves from TESS photometry. To derive transit parameters, we modelled the MuSCAT2 light curves with Gaussian processes to account for correlated noise. To derive physical parameters, we performed EXOFASTv2 global fits to the available transit and radial velocity data sets, together with the Gaia DR3 parallax, isochrones, and spectral energy distributions. To assess the potential for atmospheric characterization, we compared the multicolour transit depths with a flat line and a clear atmosphere model. We consistently refined the transit and physical parameters. We improved the orbital period and ephemeris estimates, and found no evidence for TTVs or orbital decay. The MuSCAT2 broad-band transmission spectra of HAT-P-19b and HAT-P-65b are consistent with previously published low-resolution transmission spectra. We also found that, except for HAT-P-65b, the assumption of a planetary atmosphere can improve the fit to the MuSCAT2 data. In particular, we identified HAT-P-55b as a priority target among these four planets for further atmospheric studies using transmission spectroscopy.
We present the detection of three exoplanets orbiting the early M dwarf TOI-663 (TIC 54962195;
V
= 13.7 mag,
J
= 10.4 mag,
R
★
= 0.512 ± 0.015
R
⊙
,
M
★
= 0.514 ± 0.012
M
⊙
,
d
= 64 pc). TOI-663 b, ...c, and d, with respective radii of 2.27 ± 0.10
R
⊕
, 2.26 ± 0.10
R
⊕
, and 1.92 ± 0.13
R
⊕
and masses of 4.45 ± 0.65
M
⊕
, 3.65 ± 0.97
M
⊕
, and <5.2
M
⊕
at 99%, are located just above the radius valley that separates rocky and volatile-rich exoplanets. The planet candidates are identified in two TESS sectors and are validated with ground-based photometric follow-up, precise radial-velocity measurements, and high-resolution imaging. We used the software package juliet to jointly model the photometric and radial-velocity datasets, with Gaussian processes applied to correct for systematics. The three planets discovered in the TOI-663 system are low-mass mini-Neptunes with radii significantly larger than those of rocky analogs, implying that volatiles, such as water, must predominate. In addition to this internal structure analysis, we also performed a dynamical analysis that confirmed the stability of the system. The three exoplanets in the TOI-663 system, similarly to other sub-Neptunes orbiting M dwarfs, have been found to have lower densities than planets of similar sizes orbiting stars of different spectral types.
Abstract
We report the discovery of one super-Earth- (TOI-1749b) and two sub-Neptune-sized planets (TOI-1749c and TOI-1749d) transiting an early M dwarf at a distance of 100 pc, which were first ...identified as planetary candidates using data from the TESS photometric survey. We have followed up this system from the ground by means of multiband transit photometry, adaptive optics imaging, and low-resolution spectroscopy, from which we have validated the planetary nature of the candidates. We find that TOI-1749b, c, and d have orbital periods of 2.39, 4.49, and 9.05 days, and radii of 1.4, 2.1, and 2.5
R
⊕
, respectively. We also place 95% confidence upper limits on the masses of 57, 14, and 15
M
⊕
for TOI-1749b, c, and d, respectively, from transit timing variations. The periods, sizes, and tentative masses of these planets are in line with a scenario in which all three planets initially had a hydrogen envelope on top of a rocky core, and only the envelope of the innermost planet has been stripped away by photoevaporation and/or core-powered mass-loss mechanisms. These planets are similar to other planetary trios found around M dwarfs, such as TOI-175b,c,d and TOI-270b,c,d, in the sense that the outer pair has a period ratio within 1% of 2. Such a characteristic orbital configuration, in which an additional planet is located interior to a near 2:1 period-ratio pair, is relatively rare around FGK dwarfs.
Background The NCIC Clinical Trials Group conducted the BR.21 trial, a randomized placebo-controlled trial of erlotinib (an epidermal growth factor receptor tyrosine kinase inhibitor) in patients ...with previously treated advanced non–small cell lung cancer. This trial accrued patients between August 14, 2001, and January 31, 2003, and found that overall survival and quality of life were improved in the erlotinib arm than in the placebo arm. However, funding restrictions limit access to erlotinib in many countries. We undertook an economic analysis of erlotinib treatment in this trial and explored different molecular and clinical predictors of outcome to determine the cost-effectiveness of treating various populations with erlotinib. Methods Resource utilization was determined from individual patient data in the BR.21 trial database. The trial recruited 731 patients (488 in the erlotinib arm and 243 in the placebo arm). Costs arising from erlotinib treatment, diagnostic tests, outpatient visits, acute hospitalization, adverse events, lung cancer–related concomitant medications, transfusions, and radiation therapy were captured. The incremental cost-effectiveness ratio was calculated as the ratio of incremental cost (in 2007 Canadian dollars) to incremental effectiveness (life-years gained). In exploratory analyses, we evaluated the benefits of treatment in selected subgroups to determine the impact on the incremental cost-effectiveness ratio. Results The incremental cost-effectiveness ratio for erlotinib treatment in the BR.21 trial population was $94 638 per life-year gained (95% confidence interval = $52 359 to $429 148). The major drivers of cost-effectiveness included the magnitude of survival benefit and erlotinib cost. Subgroup analyses revealed that erlotinib may be more cost-effective in never-smokers or patients with high EGFR gene copy number. Conclusion With an incremental cost-effectiveness ratio of $94 638 per life-year gained, erlotinib treatment for patients with previously treated advanced non–small cell lung cancer is marginally cost-effective. The use of molecular predictors of benefit for targeted agents may help identify more or less cost-effective subgroups for treatment.
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