Dynamic Programming for Response-Adaptive Dose-Finding Clinical Trials

Author(s):  
Amir Ali Nasrollahzadeh ◽  
Amin Khademi

Identifying the right dose is one of the most important decisions in drug development. Adaptive designs are promoted to conduct dose-finding clinical trials as they are more efficient and ethical compared with static designs. However, current techniques in response-adaptive designs for dose allocation are complex and need significant computational effort, which is a major impediment for implementation in practice. This study proposes a Bayesian nonparametric framework for estimating the dose-response curve, which uses a piecewise linear approximation to the curve by consecutively connecting the expected mean response at each dose. Our extensive numerical results reveal that a first-order Bayesian nonparametric model with a known correlation structure in prior for the expected mean response performs competitively when compared with the standard approach and other more complex models in terms of several relevant metrics and enjoys computational efficiency. Furthermore, structural properties for the optimal learning problem, which seeks to minimize the variance of the target dose, are established under this simple model. Summary of Contribution: In this work, we propose a methodology to derive efficient patient allocation rules in response-adaptive dose-finding clinical trials, where computational issues are the main concern. We show that our methodologies are competitive with the state-of-the-art methodology in terms of solution quality, are significantly more computationally efficient, and are more robust in terms of the shape of the dose-response curve, among other parameter changes. This research fits in “the intersection of computing and operations research” as it adapts operations research techniques to produce computationally attractive solutions to patient allocation problems in dose-finding clinical trials.

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1294-1294
Author(s):  
Pau Montesinos ◽  
David Martinez ◽  
Raimundo Garcia Boyero ◽  
Jaime Pérez de Oteyza ◽  
Pascual Fernandez ◽  
...  

Abstract Background and objectives Protocols for acute myeloid leukemia (AML) 1st line patients are centered on the combination of Cytarabine and an anthracycline; Idarubicin (IDA), Daunorubicin (DNR), or Mitoxantrone (MIT). Patients may be treated with IDA, DNR, or MIT depending on the country of residence, because multiple clinical trials have not found significant differences among them. A new Personalized Medicine (PM) test developed by Vivia Biotech based on pharmacological responses in patient samples (ex vivo) is uncovering individual responses to these treatments. Our objective is to explore whether a significant % of individual patients may respond differently to IDA vs DNR vs MIT treatments, in spite that of their “on average” similar response shown by clinical trials. Patients and Methods Multicenter, prospective, non-interventional study of the PETHEMA group for treatment of AML. Bone Marrow (BM) samples were collected at diagnosis for 160 AML patients. Samples were incubated for 48 hours in 96-well plates, each well containing different drugs or drug combinations, each at 8 different concentrations, enabling calculation of dose response curves for each single drug (CYT, IDA, DNR, MIT) and combination used in treatments (CYT-IDA, CYT-DNR, CYT-MIT). Drug response was evaluated as depletion of AML malignant cells in each well after 48 hours incubations. Annexin V-FITC was used to quantify the ability of the drugs to induce apoptosis. Malignant cells were identified with monoclonal antibodies and light scatter properties. 1) We use the whole bone marrow sample, retaining the erythrocyte population and serum proteins, during the entire incubation period; and after 48 h leukocytes are isolated prior to evaluation by flow cytometry. 2) We have pioneered development of a proprietary automated flow cytometry platform called ExviTech. 3) Pharmacological responses are calculated using pharmacokinetic population models. Results Figure left panel shows dose responses for both IDA (red) and DNR (blue) in 125 AML patient samples. Although their average curves (thick red & blue) are similar, the interpatient variability of either drug is quite large. We hypothesized that some patients could show very differential sensitivities to both drugs, as illustrated by the green arrow where a patient sample is resistant to DNR (right shifted dose response curve) but sensitive to IDA (left shifted dose response curve). To identify these cases Figure right panel shows a comparison of the potency IDA vs DNR. Potency is represented by their EC50 (concentration that kills 50% of the cells). Most dots tend to line up, but red dots represent patient samples with a difference in potency between these drugs >30%. Repeating this exercise for IDA-MIT and DNR-MIT to cover all alternatives among the 3 anthracyclines identifies 40% of patients samples with >30% different potency among IDA-DNR-MIT. Repeating this exercise with the combination treatments CYT-IDA, CYT-DNR, CYT-MIT increases to 58% the population of patients whose samples have a differential sensitivity to these anthracyclines. A fraction of this 57% of patients may benefit in if treatment selection among these 3 treatments were to be aided by this ex vivo testing sensitivities. To identify which fraction would benefit we would need a trial specifically designed. Conclusions This preliminary results show that Vivia's PM test seems able to identify a subset of AML patients who's ex vivo pharmacological response to anthracycline drugs is significantly different. Because this ex vivo test accurately predicts the clinical response to CYT-IDA, if these selective anthracycline ex vivo responses translate to clinical responses, a fraction of this 57% subpopulation could benefit significantly from receiving 1st or 2nd line treatments based on either IDA, DNR, MIT, and their combinations. Hence this approach stands for European integration of treatment protocols, based on ex vivo individual responses data rather than nationality. Disclosures: Primo: Vivia Biotech: Employment. Hernandez-Campo:Vivia Biotech: Employment. Rojas:Vivia Biotech: Employment. Bennett:Vivia Biotech: Employment. Liebana:Vivia Biotech: Employment. Lopez:Vivia Biotech: Employment. Ballesteros:Vivia Biotech: Equity Ownership.


2020 ◽  
Author(s):  
Xiaqing Huang ◽  
Byron Gajewski

Abstract Background: Phase II clinical trials primarily aim to find the optimal dose and investigate the relationship between dose and efficacy relative to standard of care (control). Therefore, before moving forward to a phase III confirmatory trial, the most effective dose is needed to be identified. Methods: The primary endpoint of a phase II trial is typically a binary endpoint of success or failure. The EMAX model, ubiquitous in pharmacology research, was fit for many compounds and described the data well, except for a single compound, which had nonmonotone dose–response (Thomas et al., 2014). To mitigate the risk of nonmonotone dose response one of the alternative options is a Bayesian hierarchical EMAX model (Gajewski et al., 2019). The hierarchical EMAX adapts to its environment. Results: When the dose-response curve is monotonic it enjoys the efficiency of EMAX. When the dose-response curve is non-monotonic the additional random effect hyperprior makes the hierarchical EMAX model more adjustable and flexible. However, the normal dynamic linear model (NDLM) is a useful model to explore dose-response relationships in that the efficacy at the current dose depends on the efficacy of the previous dose(s). Previous research has compared the EMAX to the hierarchical EMAX (Gajewski et al., 2019) and the EMAX to the NDLM (Liu et al., 2017), however, the hierarchical EMAX has not been directly compared to the NDLM. Conclusions: The focus of this paper is to compare these models and discuss the relative merit for each of their uses for an ongoing early phase dose selection study.


1967 ◽  
Vol 56 (4) ◽  
pp. 619-625 ◽  
Author(s):  
Hans Jacob Koed ◽  
Christian Hamburger

ABSTRACT Comparison of the dose-response curves for LH of ovine origin (NIH-LH-S8) and of human origin (IRP-HMG-2) using the OAAD test showed a small, though statistically significant difference, the dose-response curve for LH of human origin being a little flatter. Two standard curves for ovine LH obtained with 14 months' interval, were parallel but at different levels of ovarian ascorbic acid. When the mean ascorbic acid depletions were calculated as percentages of the control levels, the two curves for NIH-LH-S8 were identical. The use of standards of human origin in the OAAD test for LH activity of human preparations is recommended.


1961 ◽  
Vol 37 (4) ◽  
pp. 565-576 ◽  
Author(s):  
Richard A. Miller

ABSTRACT Four per cent formaldehyde, insulin, or epinephrine in oil was injected for 5 days into pigeons subjected to varying degrees of hypophysectomy alone or together with large lesions in the median eminence and hypothalamus. Adrenals atrophied after the removal of the pars distalis alone or together with the neurohypophysis in untreated pigeons but showed markedly hypertrophic interrenal tissue (cortex in mammals) after treatment with formaldehyde or insulin. The slope of the dose-response curve was similar in operated and unoperated pigeons. The accumulation of bile in the liver parenchyma, which may occur after removal of the pars distalis, is an endogenous stress which was associated regularly with adrenal hypertrophy. After very large lesions of the median eminence and ventral hypothalamus in addition to total hypophysectomy, adrenals hypertrophied rather than atrophied, and the response to formaldehyde paralleled that in intact and »hypohysectomized« pigeons. Interrenal tissue was stimulated regularly; chromaffin tissue was partially degranulated, sometimes showed hyperplasia with colchicine, but only occasionally appeared hypertrophied. Epinephrine in nearly lethal doses caused only minimal adrenal enlargement. After adrenal denervation followed by hypophysectomy, the adrenals were still stimulated by formaldehyde. It appears that the interrenal tissue of the pigeon responds to a humoral stimulus not of hypophyseal origin in the absence of the hypophyseal-hypothalamic system.


1963 ◽  
Vol 42 (2_Suppl) ◽  
pp. S17-S30
Author(s):  
Fred A. Kind ◽  
Ralph I. Dorfman

ABSTRACT Thirty-seven steroids have been studied as orally effective inhibitors of ovulation in the mated oestrus rabbit. Norethisterone served as the reference standard and a dose response curve was established between the 0.31 and 1.25 mg dose levels. Nine highly active anti-ovulatory compounds are described listed in a decreasing order of potency with norethisterone having the arbitrary value of one: 6-chloro-Δ6-dehydro-17α-acetoxyprogesterone (35), 6α-methyl-Δ1-dehydro-17α-acetoxyprogesterone (≥ 10), 6-fluoro-Δ6-dehydro-17α-acetoxyprogesterone(9), 6-methyl-Δ6-dehydro-17α-acetoxyprogesterone (5), Δ6-dehydro-17α-acetoxyprogesterone (≥ 3), 6α-methyl-17α-acetoxyprogesterone (2.6), 6-chloro-Δ1,6-bisdehydro-17α-acetoxyprogesterone (≥ 2), 2-hydroxymethyl-17α-methyl-17β-hydroxyandrostan-3-one (≥ 2), and 6α-fluoro-16α-methyl-17α-acetoxyprogesterone (≥ 1.25). The anti-ovulatory activity of a compound was not related necessarily to the progestational activity of a compound nor to the anti-gonadotrophic activity as measured in parabiotic rats. 6-Chloro-Δ60dehydro-17-acetoxyprogesterone was as effective by gavage as previously shown by subcutaneous injection. 2-Hydroxymethyl-17α-methyl-17β-hydroxyandrostan-3-one was at least 2.5 times more active by gavage than by injection. While 17α-acetoxyprogesterone was a very weak anti-ovulatory steroid, modifications of the structure by addition of methyl or halogen at the 6α position with or without unsaturation greatly increased the activity. 6-Chloro-Δ6-dehydro-27α-acetoxyprogesterone was the most active compound in this series showing a relative potency of 3500 times that of the parent compound 17α-acetoxyprogesterone.


2021 ◽  
Vol 17 ◽  
pp. 174480692199262
Author(s):  
Ken Iwata ◽  
Yukio Takamatsu ◽  
Nagafumi Doi ◽  
Kazutaka Ikeda

Electroconvulsive therapy (ECT) has been applied for chronic pain for decades. The amounts of opioids to treat pain are sometimes reduced after a series of ECT. The effect of ECT on morphine-induced analgesia and its mechanism underlying the reduction of morphine requirement has yet to be clarified. Therefore, we administered electroconvulsive shocks (ECS) to mice and investigated the antinociceptive effect of morphine in a hot plate test. We examined the expression level of µ-opioid receptor in the thalami of mice 25 h after administration of ECS compared to the thalami of mice without ECS administration using western blotting. ECS disturbed the development of a decrease in the percentage of maximal possible effect (%MPE), which was observed 24 h after a morphine injection, when ECS was applied 25, 23, 21, and 12 h before the second administration of morphine. We also examined the effect of ECS on the dose-response curve of %MPE to morphine-antinociception. Twenty-five hours after ECS, the dose-response curve was shifted to the left, and the EC50 of morphine given to ECS-pretreated mice decreased by 30.1% compared to the mice that were not pretreated with ECS. We also found that the expression level of µ-opioid receptors was significantly increased after ECS administration. These results confirm previous clinical reports showing that ECT decreased the required dose of opioids in neuropathic pain patients and suggest the hypothesis that this effect of ECT works through the thalamus.


1981 ◽  
Vol 27 (11) ◽  
pp. 1838-1844 ◽  
Author(s):  
G A Hudson ◽  
R F Ritchie ◽  
J E Haddow

Abstract Antiserum performance in a nephelometric system can be characterized by parameters derived from measuring reaction rates. The characterization process is derived from a series of dose-response curves (elicited nephelometric response vs antigen concentration) generated from various dilutions of the antiserum being tested. Antiserum titer can then be calculated by plotting the antigen concentration found at one-half the maximum nephelometric response (Hmax) of each dose-response curve (C50) vs the corresponding antiserum dilution. Antiserum avidity can be calculated by plotting Hmax against its corresponding antiserum concentration. After general expressions are determined for C50 and Hmax vs antiserum concentration, a single dose-response curve suffices for characterizing antisera with respect to titer and avidity. Direct evidence is provided for the validity of C50 and Hmax as measures of titer and avidity by correlating these parameters with antiserum binding strength and with the number of antibodies eluted from immobilized antigen. This method can be applied to evaluate and compare different antiserum lots having the same specificity, to identify reagent inadequacies by comparing antisera of different specificity, and to predict the optimal antiserum dilution to use in performing an assay.


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