Background:Currently,the prognosis for metastatic colorectal cancer(mCRC)still remains poor.The management of mCRC has become manifold because of the varied advances in the systemic and topical treatment approaches.Fo...Background:Currently,the prognosis for metastatic colorectal cancer(mCRC)still remains poor.The management of mCRC has become manifold because of the varied advances in the systemic and topical treatment approaches.For patients with limited number of metastases,radical local therapy plus systemic therapy can be a good choice to achieve long-term tumor control.In this study,we aimed to explore the efficacy and safety of the combination of fruquintinib,tislelizumab,and stereotactic ablative radiotherapy(SABR)in mCRC(RIFLE study).Methods:RIFLE was designed as a single-center,single-arm,prospective Phase II clinical trial.A total of 68 mCRC patients who have failed the first-line standard treatment will be recruited in the safety run-in phase(n=6)and the expansion phase(n=62),respectively.Eligible patients will receive SABR followed by fruquintinib(5 mg,d1–14,once every day)and tislelizumab(200 mg,d1,once every 3 weeks)within 2 weeks from completion of radiation.The expansion phase starts when the safety of the treatment is determined(dose limiting toxicity occur in no more than one-sixth of patients in the run-in phase).The primary end point is the objective response rate.The secondary end points include the disease control rate,duration of response,3-year progression-free survival rate,3-year overall survival rate,and toxicity.Conclusions:The results of this trial will provide a novel insight into SABR in combination with PD-1 antibody and vascular endothelial growth factor receptor inhibitor in the systematic treatment of metastatic colorectal cancer,which is expected to provide new therapeutic strategies and improve the prognosis for mCRC patients.Trial registration:NCT04948034(ClinicalTrials.gov).展开更多
We develop two new pricing formulae for European options. The purpose of these formulae is to better understand the impact of each term of the model, as well as improve the speed of the calculations. We consider the S...We develop two new pricing formulae for European options. The purpose of these formulae is to better understand the impact of each term of the model, as well as improve the speed of the calculations. We consider the SABR model (with β=1) of stochastic volatility, which we analyze by tools from Malliavin Calculus. We follow the approach of Alòs et al. (2006) who showed that under stochastic volatility framework, the option prices can be written as the sum of the classic Hull-White (1987) term and a correction due to correlation. We derive the Hull-White term, by using the conditional density of the average volatility, and write it as a two-dimensional integral. For the correction part, we use two different approaches. Both approaches rely on the pairing of the exponential formula developed by Jin, Peng, and Schellhorn (2016) with analytical calculations. The first approach, which we call “Dyson series on the return’s idiosyncratic noise” yields a complete series expansion but necessitates the calculation of a 7-dimensional integral. Two of these dimensions come from the use of Yor’s (1992) formula for the joint density of a Brownian motion and the time-integral of geometric Brownian motion. The second approach, which we call “Dyson series on the common noise” necessitates the calculation of only a one-dimensional integral, but the formula is more complex. This research consisted of both analytical derivations and numerical calculations. The latter show that our formulae are in general more exact, yet more time-consuming to calculate, than the first order expansion of Hagan et al. (2002).展开更多
This work aims at quantifying intra-fractional motion errors and evaluating the appropriateness of a Planning Target Volume (PTV) margin for Queen Elizabeth (QE) Hospital’s patients. Intra-fractional motion errors we...This work aims at quantifying intra-fractional motion errors and evaluating the appropriateness of a Planning Target Volume (PTV) margin for Queen Elizabeth (QE) Hospital’s patients. Intra-fractional motion errors were quantified for 29 patients who underwent lung Stereotactic Ablative Radiotherapy (SABR) treatment at the cancer centre of QE Hospital. One hundred thirty post-Cone Beam Computed Tomography (CBCT) scans were collected to calculate these errors. In terms of the adequacy of a PTV margin, the intra-fractional motion errors that were calculated are combined with other geometric errors which were taken from historical audit studies. Then, the combined outcome was compared with the common PTV margin that is delineated by most United Kingdom (UK) oncology centres. The findings of this study showed that the systematic component of intra-fractional motion error is equal to 0.08, 0.08 and 0.08 cm in right/left, superior/anterior and anterior/posterior directions, respectively, While the random component of this error is equal to 0.11, 0.13 and 0.14 cm. In addition to that, a PTV margin of 0.5 cm is the appropriate margin for QE Hospital’s patients and this volume is compatible with the common PTV margin that is delineated by the most UK oncology centres. This work concluded that A PTV margin of 0.5 cm is the suitable volume for lung SABR patients at QE Hospital.展开更多
The SABR stochastic volatility model with β-volatility β ? (0,1) and an absorbing barrier in zero imposed to the forward prices/rates stochastic process is studied. The presence of (possibly) nonzero correlation bet...The SABR stochastic volatility model with β-volatility β ? (0,1) and an absorbing barrier in zero imposed to the forward prices/rates stochastic process is studied. The presence of (possibly) nonzero correlation between the stochastic differentials that appear on the right hand side of the model equations is considered. A series expansion of the transition probability density function of the model in powers of the correlation coefficient of these stochastic differentials is presented. Explicit formulae for the first three terms of this expansion are derived. These formulae are integrals of known integrands. The zero-th order term of the expansion is a new integral formula containing only elementary functions of the transition probability density function of the SABR model when the correlation coefficient is zero. The expansion is deduced from the final value problem for the backward Kolmogorov equation satisfied by the transition probability density function. Each term of the expansion is defined as the solution of a final value problem for a partial differential equation. The integral formulae that give the solutions of these final value problems are based on the Hankel and on the Kontorovich-Lebedev transforms. From the series expansion of the probability density function we deduce the corresponding expansions of the European call and put option prices. Moreover we deduce closed form formulae for the moments of the forward prices/rates variable. The moment formulae obtained do not involve integrals or series expansions and are expressed using only elementary functions. The option pricing formulae are used to study synthetic and real data. In particular we study a time series (of real data) of futures prices of the EUR/USD currency's exchange rate and of the corresponding option prices. The website: http://www.econ.univpm.it/recchioni/finance/w18 contains material including animations, an interactive application and an app that helps the understanding of the paper. A more general reference to the work of the a展开更多
We study two calibration problems for the lognormal SABR model using the moment method and some new formulae for the moments of the logarithm of the forward prices/rates variable. The lognormal SABR model is a special...We study two calibration problems for the lognormal SABR model using the moment method and some new formulae for the moments of the logarithm of the forward prices/rates variable. The lognormal SABR model is a special case of the SABR model [1]. The acronym “SABR” means “Stochastic-αβρ” and comes from the original names of the model parameters (i.e., α,β,ρ) [1]. The SABR model is a system of two stochastic differential equations widely used in mathematical finance whose independent variable is time and whose dependent variables are the forward prices/rates and the associated stochastic volatility. The lognormal SABR model corresponds to the choice β = 1 and depends on three quantities: the parameters??α,ρ and the initial stochastic volatility. In fact the initial stochastic volatility cannot be observed and can be regarded as a parameter. A calibration problem is an inverse problem that consists in determineing the values of these three parameters starting from a set of data. We consider two different sets of data, that is: i) the set of the forward prices/rates observed at a given time on multiple independent trajectories of the lognormal SABR model, ii) the set of the forward prices/rates observed on a discrete set of known time values along a single trajectory of the lognormal SABR model. The calibration problems corresponding to these two sets of data are formulated as constrained nonlinear least-squares problems and are solved numerically. The formulation of these nonlinear least-squares problems is based on some new formulae for the moments of the logarithm of the forward prices/rates. Note that in the financial markets the first set of data considered is hardly available while the second set of data is of common use and corresponds simply to the time series of the observed forward prices/rates. As a consequence the first calibration problem although realistic in several contexts of science and engineering is of limited interest in finance while the second calibration problem is of practica展开更多
The stochastic alpha beta rho(SABR)model introduced by Hagan et al.(2002)is widely used in both fixed income and the foreign exchange(FX)markets.Continuously monitored barrier option contracts are among the most popul...The stochastic alpha beta rho(SABR)model introduced by Hagan et al.(2002)is widely used in both fixed income and the foreign exchange(FX)markets.Continuously monitored barrier option contracts are among the most popular derivative contracts in the FX markets.In this paper,we develop closed-form formulas to approximate various types of barrier option prices(down-and-out/in,up-and-out/in)under the SABR model.We first derive an approximate formula for the survival density.The barrier option price is the one-dimensional integral of its payoff function and the survival density,which can be easily implemented and quickly evaluated.The approximation error of the survival density is also analyzed.To the best of our knowledge,it is the first time that analytical(approximate)formulas for the survival density and the barrier option prices for the SABR model are derived.Numerical experiments demonstrate the validity and efficiency of these formulas.展开更多
基金supported by the National Nature Science Foundation of China[grant number:82102978].
文摘Background:Currently,the prognosis for metastatic colorectal cancer(mCRC)still remains poor.The management of mCRC has become manifold because of the varied advances in the systemic and topical treatment approaches.For patients with limited number of metastases,radical local therapy plus systemic therapy can be a good choice to achieve long-term tumor control.In this study,we aimed to explore the efficacy and safety of the combination of fruquintinib,tislelizumab,and stereotactic ablative radiotherapy(SABR)in mCRC(RIFLE study).Methods:RIFLE was designed as a single-center,single-arm,prospective Phase II clinical trial.A total of 68 mCRC patients who have failed the first-line standard treatment will be recruited in the safety run-in phase(n=6)and the expansion phase(n=62),respectively.Eligible patients will receive SABR followed by fruquintinib(5 mg,d1–14,once every day)and tislelizumab(200 mg,d1,once every 3 weeks)within 2 weeks from completion of radiation.The expansion phase starts when the safety of the treatment is determined(dose limiting toxicity occur in no more than one-sixth of patients in the run-in phase).The primary end point is the objective response rate.The secondary end points include the disease control rate,duration of response,3-year progression-free survival rate,3-year overall survival rate,and toxicity.Conclusions:The results of this trial will provide a novel insight into SABR in combination with PD-1 antibody and vascular endothelial growth factor receptor inhibitor in the systematic treatment of metastatic colorectal cancer,which is expected to provide new therapeutic strategies and improve the prognosis for mCRC patients.Trial registration:NCT04948034(ClinicalTrials.gov).
文摘We develop two new pricing formulae for European options. The purpose of these formulae is to better understand the impact of each term of the model, as well as improve the speed of the calculations. We consider the SABR model (with β=1) of stochastic volatility, which we analyze by tools from Malliavin Calculus. We follow the approach of Alòs et al. (2006) who showed that under stochastic volatility framework, the option prices can be written as the sum of the classic Hull-White (1987) term and a correction due to correlation. We derive the Hull-White term, by using the conditional density of the average volatility, and write it as a two-dimensional integral. For the correction part, we use two different approaches. Both approaches rely on the pairing of the exponential formula developed by Jin, Peng, and Schellhorn (2016) with analytical calculations. The first approach, which we call “Dyson series on the return’s idiosyncratic noise” yields a complete series expansion but necessitates the calculation of a 7-dimensional integral. Two of these dimensions come from the use of Yor’s (1992) formula for the joint density of a Brownian motion and the time-integral of geometric Brownian motion. The second approach, which we call “Dyson series on the common noise” necessitates the calculation of only a one-dimensional integral, but the formula is more complex. This research consisted of both analytical derivations and numerical calculations. The latter show that our formulae are in general more exact, yet more time-consuming to calculate, than the first order expansion of Hagan et al. (2002).
文摘This work aims at quantifying intra-fractional motion errors and evaluating the appropriateness of a Planning Target Volume (PTV) margin for Queen Elizabeth (QE) Hospital’s patients. Intra-fractional motion errors were quantified for 29 patients who underwent lung Stereotactic Ablative Radiotherapy (SABR) treatment at the cancer centre of QE Hospital. One hundred thirty post-Cone Beam Computed Tomography (CBCT) scans were collected to calculate these errors. In terms of the adequacy of a PTV margin, the intra-fractional motion errors that were calculated are combined with other geometric errors which were taken from historical audit studies. Then, the combined outcome was compared with the common PTV margin that is delineated by most United Kingdom (UK) oncology centres. The findings of this study showed that the systematic component of intra-fractional motion error is equal to 0.08, 0.08 and 0.08 cm in right/left, superior/anterior and anterior/posterior directions, respectively, While the random component of this error is equal to 0.11, 0.13 and 0.14 cm. In addition to that, a PTV margin of 0.5 cm is the appropriate margin for QE Hospital’s patients and this volume is compatible with the common PTV margin that is delineated by the most UK oncology centres. This work concluded that A PTV margin of 0.5 cm is the suitable volume for lung SABR patients at QE Hospital.
文摘The SABR stochastic volatility model with β-volatility β ? (0,1) and an absorbing barrier in zero imposed to the forward prices/rates stochastic process is studied. The presence of (possibly) nonzero correlation between the stochastic differentials that appear on the right hand side of the model equations is considered. A series expansion of the transition probability density function of the model in powers of the correlation coefficient of these stochastic differentials is presented. Explicit formulae for the first three terms of this expansion are derived. These formulae are integrals of known integrands. The zero-th order term of the expansion is a new integral formula containing only elementary functions of the transition probability density function of the SABR model when the correlation coefficient is zero. The expansion is deduced from the final value problem for the backward Kolmogorov equation satisfied by the transition probability density function. Each term of the expansion is defined as the solution of a final value problem for a partial differential equation. The integral formulae that give the solutions of these final value problems are based on the Hankel and on the Kontorovich-Lebedev transforms. From the series expansion of the probability density function we deduce the corresponding expansions of the European call and put option prices. Moreover we deduce closed form formulae for the moments of the forward prices/rates variable. The moment formulae obtained do not involve integrals or series expansions and are expressed using only elementary functions. The option pricing formulae are used to study synthetic and real data. In particular we study a time series (of real data) of futures prices of the EUR/USD currency's exchange rate and of the corresponding option prices. The website: http://www.econ.univpm.it/recchioni/finance/w18 contains material including animations, an interactive application and an app that helps the understanding of the paper. A more general reference to the work of the a
文摘We study two calibration problems for the lognormal SABR model using the moment method and some new formulae for the moments of the logarithm of the forward prices/rates variable. The lognormal SABR model is a special case of the SABR model [1]. The acronym “SABR” means “Stochastic-αβρ” and comes from the original names of the model parameters (i.e., α,β,ρ) [1]. The SABR model is a system of two stochastic differential equations widely used in mathematical finance whose independent variable is time and whose dependent variables are the forward prices/rates and the associated stochastic volatility. The lognormal SABR model corresponds to the choice β = 1 and depends on three quantities: the parameters??α,ρ and the initial stochastic volatility. In fact the initial stochastic volatility cannot be observed and can be regarded as a parameter. A calibration problem is an inverse problem that consists in determineing the values of these three parameters starting from a set of data. We consider two different sets of data, that is: i) the set of the forward prices/rates observed at a given time on multiple independent trajectories of the lognormal SABR model, ii) the set of the forward prices/rates observed on a discrete set of known time values along a single trajectory of the lognormal SABR model. The calibration problems corresponding to these two sets of data are formulated as constrained nonlinear least-squares problems and are solved numerically. The formulation of these nonlinear least-squares problems is based on some new formulae for the moments of the logarithm of the forward prices/rates. Note that in the financial markets the first set of data considered is hardly available while the second set of data is of common use and corresponds simply to the time series of the observed forward prices/rates. As a consequence the first calibration problem although realistic in several contexts of science and engineering is of limited interest in finance while the second calibration problem is of practica
基金support of the China National Social Science Fund under Grant No.15BJL093Yanchu Liu is partially supported by the National Natural Science Foundation of China under Grant No.71501196,No.71231008,No.71721001+4 种基金the China National Social Science Fund under Grant No.17ZDA073the Natural Science Foundation of Guangdong Province of China under Grant No.2014A030312003the Innovative Research Team Project of Guangdong Province of China under Grant No.2016WCXTD001the Fundamental Research Funds for the Central Universities under Grant No.14wkpy63research grants from Lingnan(University)College and Advanced Research Institute of Finance at Sun Yat-sen University.
文摘The stochastic alpha beta rho(SABR)model introduced by Hagan et al.(2002)is widely used in both fixed income and the foreign exchange(FX)markets.Continuously monitored barrier option contracts are among the most popular derivative contracts in the FX markets.In this paper,we develop closed-form formulas to approximate various types of barrier option prices(down-and-out/in,up-and-out/in)under the SABR model.We first derive an approximate formula for the survival density.The barrier option price is the one-dimensional integral of its payoff function and the survival density,which can be easily implemented and quickly evaluated.The approximation error of the survival density is also analyzed.To the best of our knowledge,it is the first time that analytical(approximate)formulas for the survival density and the barrier option prices for the SABR model are derived.Numerical experiments demonstrate the validity and efficiency of these formulas.
