Integration of Pharmacokinetics, Pharmacodynamics, Safety, and Efficacy into Model-Informed Dose Selection in Oncology First-in-Human Study: A Case of Roblitinib (FGF401)

Model-informed dose selection has been drawing increasing interest in oncology early clinical development. The current paper describes the example of FGF401, a selective fibroblast growth factor receptor 4 (FGFR4) inhibitor, in which a comprehensive modeling and simulation (M&S) framework, using both pharmacometrics and statistical methods, was established during its first-in-human clinical development using the totality of pharmacokinetics (PK), pharmacodynamic (PD) biomarkers, and safety and efficacy data in patients with cancer. These M&S results were used to inform FGF401 dose selection for future development. A two-compartment population PK (PopPK) model with a delayed 0-order absorption and linear elimination adequately described FGF401 PK. Indirect PopPK/PD models including a precursor compartment were independently established for two biomarkers: circulating FGF19 and 7α-hydroxy-4-cholesten-3-one (C4). Model simulations indicated a close-to-maximal PD effect achieved at the clinical exposure range. Time-to-progression was analyzed by Kaplan-Meier method which favored a trough concentration (C_trough )-driven efficacy requiring C_trough above a threshold close to the drug concentration producing 90% inhibition of phospho-FGFR4. Clinical tumor growth inhibition was described by a PopPK/PD model that reproduced the dose-dependent effect on tumor growth. Exposure-safety analyses on the expected on-target adverse events, including elevation of aspartate aminotransferase and diarrhea, indicated a lack of clinically relevant relationship with FGF401 exposure. Simulations from an indirect PopPK/PD model established for alanine aminotransferase, including a chain of three precursor compartments, further supported that maximal target inhibition was achieved and there was a lack of safety-exposure relationship. This M&S framework supported a dose selection of 120 mg once daily fasted or with a low-fat meal and provides a practical example that might be applied broadly in oncology early clinical development.

Contribution of machine learning to tumor growth inhibition modeling for hepatocellular carcinoma patients under Roblitinib (FGF401) drug treatment

Machine learning (ML) opens new perspectives in identifying predictive factors of efficacy among a large number of patients’ characteristics in oncology studies. The objective of this work was to combine ML with population pharmacokinetic/pharmacodynamic (PK/PD) modeling of tumor growth inhibition to understand the sources of variability between patients and therefore improve model predictions to support drug development decisions. Data from 127 patients with hepatocellular carcinoma enrolled in a phase I/II study evaluating once‐daily oral doses of the fibroblast growth factor receptor FGFR4 kinase inhibitor, Roblitinib (FGF401), were used. Roblitinib  PKs was best described by a two‐compartment model with a delayed zero‐order absorption and linear elimination. Clinical efficacy using the longitudinal sum of the longest lesion diameter data was described with a population PK/PD model of tumor growth inhibition including resistance to treatment. ML, applying elastic net modeling of time to progression data, was associated with cross‐validation, and allowed to derive a composite predictive risk score from a set of 75 patients’ baseline characteristics. The two approaches were combined by testing the inclusion of the continuous risk score as a covariate on PD model parameters. The score was found as a significant covariate on the resistance parameter and resulted in 19% reduction of its variability, and 32% variability reduction on the average dose for stasis. The final PK/PD model was used to simulate effect of patients’ characteristics on tumor growth inhibition profiles. The proposed methodology can be used to support drug development decisions, especially when large interpatient variability is observed.

Results from a First-in-Human Phase I Study of Siremadlin (HDM201) in Patients with Advanced Wild-Type TP53 Solid Tumors and Acute Leukemia

PURPOSE

This phase I, dose-escalation study investigated the recommended dose for expansion (RDE) of siremadlin, a p53-MDM2 inhibitor, in patients with wild-type TP53 advanced solid or hematologic cancers.

PATIENTS AND METHODS

Initial dosing regimens were: 1A (day 1; 21-day cycle; dose 12.5-350 mg) and 2A (days 1-14; 28-day cycle; dose 1-20 mg). Alternative regimens included 1B (days 1 and 8; 28-day cycle) and 2C (days 1-7; 28-day cycle). The primary endpoint was incidence of dose-limiting toxicities (DLT) during cycle 1.

RESULTS

Overall, 115 patients with solid tumors and 93 with hematologic malignancies received treatment. DLTs occurred in 8/92 patients with solid tumors and 10/53 patients with hematologic malignancies. In solid tumors, an RDE of 120 mg was defined in 1B. In hematologic tumors, RDEs were defined in 1A: 250 mg, 1B: 120 mg, and 2C: 45 mg. More patients with hematologic malignancies compared with solid tumors experienced grade 3/4 treatment-related adverse events (71% vs. 45%), most commonly resulting from myelosuppression. These were more frequent and severe in patients with hematologic malignancies; 22 patients exhibited tumor lysis syndrome. Overall response rates at the RDEs were 10.3% [95% confidence interval (CI), 2.2-27.4] in solid tumors and 4.2% (95% CI, 0.1-21.1), 20% (95% CI, 4.3-48.1), and 22.2% (95% CI, 8.6-42.3) in acute myeloid leukemia (AML) in 1B, 1A, and 2C, respectively.

CONCLUSIONS

A common safety profile was identified and preliminary activity was noted, particularly in AML. Comprehensive investigation of dosing regimens yielded recommended doses/regimens for future combination studies.

A framework to guide dose & regimen strategy for clinical drug development

Optimizing new drug therapies remains a challenge for clinical development, despite the use of ever more sophisticated quantitative methodologies. Although conceptually simple, the idea of finding the right treatment at the right dose for the right patient to ensure an appropriate balance of risks and benefits is challenging and requires a multidisciplinary approach. In this paper, we present a framework developed as a tool for organizing knowledge and facilitating collaboration in development teams.

Pharmacokinetic-pharmacodynamic guided optimisation of dose and schedule of CGM097, an HDM2 inhibitor, in preclinical and clinical studies

BACKGROUND

CGM097 inhibits the p53-HDM2 interaction leading to downstream p53 activation. Preclinical in vivo studies support clinical exploration while providing preliminary evidence for dosing regimens. This first-in-human phase I study aimed at assessing the safety, MTD, PK/PD and preliminary antitumor activity of CGM097 in advanced solid tumour patients (NCT01760525).

METHODS

Fifty-one patients received oral treatment with CGM097 10-400 mg 3qw (n = 31) or 300-700 mg 3qw 2 weeks on/1 week off (n = 20). Choice of dose regimen was guided by PD biomarkers, and quantitative models describing the effect of CGM097 on circulating platelet and PD kinetics.

RESULTS

No dose-limiting toxicities were reported in any regimens. The most common treatment-related grade 3/4 AEs were haematologic events. PK/PD models well described the time course of platelet and serum GDF-15 changes, providing a tool to predict response to CGM097 for dose-limiting thrombocytopenia and GDF-15 biomarker. The disease control rate was 39%, including one partial response and 19 patients in stable disease. Twenty patients had a cumulative treatment duration of >16 weeks, with eight patients on treatment for >32 weeks. The MTD was not determined.

CONCLUSIONS

Despite delayed-onset thrombocytopenia frequently observed, the tolerability of CGM097 appears manageable. This study provided insights on dosing optimisation for next-generation HDM2 inhibitors.

TRANSLATIONAL RELEVANCE

Haematologic toxicity with delayed thrombocytopenia is a well-known on-target effect of HDM2 inhibitors. Here we have developed a PK/PD guided approach to optimise the dose and schedule of CGM097, a novel HDM2 inhibitor, using exposure, platelets and GDF-15, a known p53 downstream target to predict patients at higher risk to develop thrombocytopenia. While CGM097 had shown limited activity, with disease control rate of 39% and only one patient in partial response, the preliminary data from the first-in-human escalation study together with the PK/PD modeling provide important insights on how to optimize dosing of next generation HDM2 inhibitors to mitigate hematologic toxicity.

Asciminib in Chronic Myeloid Leukemia after ABL Kinase Inhibitor Failure

BACKGROUND

Asciminib is an allosteric inhibitor that binds a myristoyl site of the BCR-ABL1 protein, locking BCR-ABL1 into an inactive conformation through a mechanism distinct from those for all other ABL kinase inhibitors. Asciminib targets both native and mutated BCR-ABL1, including the gatekeeper T315I mutant. The safety and antileukemic activity of asciminib in patients with Philadelphia chromosome-positive leukemia are unknown.

METHODS

In this phase 1, dose-escalation study, we enrolled 141 patients with chronic-phase and 9 with accelerated-phase chronic myeloid leukemia (CML) who had resistance to or unacceptable side effects from at least two previous ATP-competitive tyrosine kinase inhibitors (TKIs). The primary objective was to determine the maximum tolerated dose or the recommended dose (or both) of asciminib. Asciminib was administered once or twice daily (at doses of 10 to 200 mg). The median follow-up was 14 months.

RESULTS

Patients were heavily pretreated; 70% (105 of 150 patients) had received at least three TKIs. The maximum tolerated dose of asciminib was not reached. Among patients with chronic-phase CML, 34 (92%) with a hematologic relapse had a complete hematologic response; 31 (54%) without a complete cytogenetic response at baseline had a complete cytogenetic response. A major molecular response was achieved or maintained by 12 months in 48% of patients who could be evaluated, including 8 of 14 (57%) deemed to have resistance to or unacceptable side effects from ponatinib. A major molecular response was achieved or maintained by 12 months in 5 patients (28%) with a T315I mutation at baseline. Clinical responses were durable; a major molecular response was maintained in 40 of 44 patients. Dose-limiting toxic effects included asymptomatic elevations in the lipase level and clinical pancreatitis. Common adverse events included fatigue, headache, arthralgia, hypertension, and thrombocytopenia.

CONCLUSIONS

Asciminib was active in heavily pretreated patients with CML who had resistance to or unacceptable side effects from TKIs, including patients in whom ponatinib had failed and those with a T315I mutation. (Funded by Novartis Pharmaceuticals; ClinicalTrials.gov number, NCT02081378.).

Abstract CT009: Results of a dose- and regimen-finding Phase Ib study of HDM201 in combination with ribociclib in patients with locally advanced or metastatic liposarcoma

Background: Well-differentiated/dedifferentiated liposarcoma (WDLPS/DDLPS) is characterized by a consistent coamplification of human double minute 2 homolog (HDM2) and cyclin-dependent kinase 4 (CDK4) which inactivates the tumor suppressor pathways p53 and Rb, respectively. HDM201 is a selective inhibitor of the p53-HDM2 interaction and ribociclib is a CDK4/6 inhibitor. Preclinical studies suggested a synergy in in vitro and in vivo models of WDLPS/DDLPS and both agents have demonstrated single-agent clinical activity in solid tumors. We aim to determine the optimal dose and regimen of HDM201 + ribociclib and to assess the preliminary antitumor activity of this combination in patients (pts) with liposarcoma.

Methods: In this multicenter, open-label, Phase Ib ongoing study, pts with locally advanced or metastatic liposarcoma that had unequivocally progressed on, or despite prior systemic therapy were treated orally with HDM201 + ribociclib. Three treatment regimens were explored: Regimen (Reg) 1 (HDM201 + ribociclib daily for the first 2 wks [QD 1st 2 wks] in a 4-wk cycle), Reg 4 (HDM201 every 3 wks + ribociclib QD 1st 2 wks in a 3-wk cycle), and Reg 5 (HDM201 every 4 wks + ribociclib QD 1st 2 wks in a 4-wk cycle).

Results: As of Nov 21, 2017, 74 pts received HDM201 + ribociclib (Reg 1 n=26; Reg 4 n=29; Reg 5 n=19); 12 pts (6 each in Reg 4 and 5) were still receiving treatment. Ten pts (Reg 1 n=3; Reg 4 n=6; Reg 5 n=1) discontinued treatment due to adverse events (AEs) and 2 pts (1 each in Reg 4 and 5) died. The most common AE of any grade, regardless of cause, reported across regimens (Reg 1; Reg 4; Reg 5) was nausea (81%; 76%; 63%) which was mainly Grade 1/2 and not dose limiting. Common Grade 3/4 AEs regardless of cause included neutropenia (39%; 52%; 42%), thrombocytopenia (35%; 45%; 42%), anemia (27%; 17%; 21%), leukopenia (27%; 28%; 37%), and lymphopenia (15%; 14%; 21%). Dose-limiting toxicities were reported in 16 pts (2; 9; 5) and all except 1 (prolonged QT) were hematologic (including neutropenia [n=5], thrombocytopenia [n=4], febrile neutropenia, and anemia [n=2 each]).

Partial responses were observed in 3 (4%) pts (2 in Reg 4; 1 in Reg 5). Stable disease was achieved by 36 (49%) pts (11 in Reg 1; 16 in Reg 4; 9 in Reg 5). The median progression-free survival (PFS) was 2.7 mo (95% confidence interval [CI]: 1.9-8.2 mo) in Reg 1, 4.8 mo (95% CI: 3.9 mo-not reached) in Reg 4, and 2.1 mo (95% CI: 1.4 mo-not reached) in Reg 5.

Conclusions: HDM201 + ribociclib demonstrated a manageable safety profile and preliminary efficacy in pts with locally advanced or metastatic WDLPS/DDLPS, with hematologic toxicities being dose limiting. The median PFS in Reg 4 compares favorably with single-agent CDK4 inhibitors and, alongside a tolerable safety profile, suggests further exploration of this regimen may be warranted in Phase II studies of HDM201 + ribociclib in this patient population.

Citation Format: Albiruni Abdul Razak, Sebastian Bauer, Jean-Yves Blay, Richard Quek, Cristina Suárez, Chia-Chi Lin, Marie L. Hütter-Krönke, Ricardo Cubedo, Stephane Ferretti, Christophe Meille, Ensar Halilovic, Giorgia Clementi, Maria Santos-Rosa, Nelson Guerreiro, Astrid Jullion, Claire Fabre, Antoine Italiano. Results of a dose- and regimen-finding Phase Ib study of HDM201 in combination with ribociclib in patients with locally advanced or metastatic liposarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT009.

Modeling therapeutic response to radioiodine in metastatic thyroid cancer: a proof-of-concept study for individualized medicine

Purpose

Radioiodine therapy (RAI) has traditionally been used as treatment for metastatic thyroid cancer, based on its ability to concentrate iodine. Propositions to maximize tumor response with minimizing toxicity, must recognize the infinite possibilities of empirical tests. Therefore, an approach of this study was to build a mathematical model describing tumor growth with the kinetics of thyroglobulin (Tg) concentrations over time, following RAI for metastatic thyroid cancer.

Experimental Design

Data from 50 patients with metastatic papillary thyroid carcinoma treated within eight French institutions, followed over 3 years after initial RAI treatments, were included in the model. A semi-mechanistic mathematical model that describes the tumor growth under RAI treatment was designed.

Results

Our model was able to separate patients who responded to RAI from those who did not, concordant with the physicians' determination of therapeutic response. The estimated tumor doubling-time (Td was found to be the most informative parameter for the distinction between responders and non-responders. The model was also able to reclassify particular patients in early treatment stages.

Conclusions

The results of the model present classification criteria that could indicate whether patients will respond or not to RAI treatment, and provide the opportunity to perform personalized management plans.

Abstract CT150: Optimizing the therapeutic index of HDM2 inhibition: Results from a dose- and regimen-finding Phase I study of NVP-HDM201 in pts with TP53 wt advanced tumors

Background: NVP-HDM201 is a selective inhibitor of the p53-HDM2 interaction, and has demonstrated potent single-agent activity in various in vitro and in vivo tumor models dependent on wild-type (wt) TP53. This study aims to determine the optimal dose and schedule of NVP-HDM201 for treating patients (pts) with TP53 wt tumors for further clinical study. Here we report results from pts with solid tumors.

Methods: In this multicenter, open-label, Phase I, ongoing study, pts with advanced TP53 wt tumors progressing on standard therapy or for whom no standard therapy exists were treated with single-agent oral NVP-HDM201. Four treatment regimens of NVP-HDM201 are explored: two high-dose intermittent regimens, Regimen (Reg) 1A (single dose [SD] on Day 1 in a 3-week [wk] cycle) and Reg 1B (SD on Days 1 and 8 in a 4-wk cycle); and two low-dose extended regimens, Reg 2A (SD every day for first 2 wks in a 4-wk cycle) and Reg 2C (SD every day for first wk in a 4-wk cycle).

Results: As of the data cut-off (Sep 19, 2016), 85 pts received NVP-HDM201 (Reg 1A n=26; Reg 1B n=20; Reg 2A n=20; Reg 2C n=19); 13% were still receiving treatment. Common Grade 3/4 adverse events (AEs) suspected to be treatment related (Reg 1A; Reg 1B; Reg 2A; Reg 2C) included neutropenia (23%; 25%; 15%; 5%), thrombocytopenia (23%; 10%; 20%; 11%), and anemia (12%; 0%; 20%; 16%); the first two were dose limiting in 4 pts (2; 1; 0; 1). Gastrointestinal toxicity was predominantly low grade, and not dose limiting; the most common treatment-related AE reported was nausea (62%; 60%; 40%; 42%). Median duration of exposure across all regimens was 8.5 weeks (range: 2-86 weeks). Partial responses were observed in 2 (2%) pts (1 in Reg 1A and 1 in Reg 1B). Stable disease was achieved by 29 (34%) pts (8 in Reg 1A, and 7 each in Reg 1B, Reg 2A and Reg 2C). Furthermore, the average plasma concentration per cycle reached with Reg 1A/Reg 1B was closer to the predicted preclinical target efficacious levels required for tumor regression compared with Reg 2A/Reg 2C, and is associated with the observed clinical activity. NVP-HDM201 showed approximate dose-proportional pharmacokinetics, and exposure correlated with blood concentrations of the GDF-15 biomarker on day 1.

Conclusions: NVP-HDM201 demonstrated a manageable safety profile and clinical activity in a heavily pretreated population. Dose-limiting toxicities consisted primarily of neutropenia and thrombocytopenia. Reg 1B was chosen for the expansion phase as it achieved the most favorable therapeutic index: the lowest incidence of Grade 3/4 thrombocytopenia while achieving therapeutically relevant exposures. The recommended dose for expansion was declared as 120 mg NVP-HDM201 and the expansion phase is enrolling. To enhance the safety and efficacy of NVP-HDM201, a separate cohort combining NVP-HDM201 with eltrombopag to mitigate thrombocytopenia is being investigated and will be reported.

Citation Format: David M. Hyman, Manik Chatterjee, Filip de Vos, Chia-Chi Lin, Cristina Suárez, David Tai, Philippe Cassier, Noboru Yamamoto, Vincent A. de Weger, Sébastien Jeay, Christophe Meille, Ensar Halilovic, Luisa Mariconti, Matthieu Klopfenstein, Nelson Guerreiro, Rajkumar Radhakrishnan, Emil T. Kuriakose, Sebastian Bauer. Optimizing the therapeutic index of HDM2 inhibition: Results from a dose- and regimen-finding Phase I study of NVP-HDM201 in pts with TP53 wt advanced tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT150. doi:10.1158/1538-7445.AM2017-CT150

Abstract CT152: Phase I dose- and regimen-finding study of NVP-HDM201 in pts with advanced TP53 wt acute leukemias

Background: NVP-HDM201 is a selective inhibitor of the p53-HDM2 interaction and has demonstrated potent single-agent activity in various in vitro and in vivo tumor models, dependent on wild-type (wt) TP53. This study aims to determine the optimal dose and schedule of NVP-HDM201 for treating patients (pts) with TP53 wt tumors for further clinical study. Here we focus on pts with advanced, TP53 wt acute leukemias.

Methods: In this multicenter, open-label, dose-finding, Phase I study, pts with advanced, TP53 wt tumors who had relapsed or refractory acute myeloid leukemia (AML) or acute lymphoblastic leukemia (ALL) were treated with single-agent oral NVP-HDM201. Four treatment regimens were explored: two high-dose intermittent regimens (reg), Reg 1A and 1B (1A: Day 1 of a 3-week [wk] cycle; 1B: Days 1 and 8 of a 4-wk cycle) and two low-dose extended regimens, Reg 2A and 2C (2A: once daily for the first 2 wks of a 4-wk cycle; 2C: once daily for the first wk of a 4-wk cycle).

Results: As of Dec 07, 2016, a total of 37 pts, comprising 35 pts with AML and 2 pts with ALL, had been enrolled in the study (Reg 1A n=16; Reg 1B n=6; Reg 2A n=7; Reg 2C n=8); treatment is ongoing in 3 pts (2 in Reg 1B and 1 in Reg 2C). The most common Grade 3/4 adverse events (AEs) suspected to be treatment-related (occurring in ≥25% of pts; Reg 1A; Reg 1B; Reg 2A; Reg 2C) were thrombocytopenia (50%; 50%; 29%; 50%), tumor lysis syndrome (TLS; 44%; 0; 14%; 13%), neutropenia (38%; 17%; 0; 25%), anemia (25%; 33%; 29%; 38%), febrile neutropenia (25%; 33%; 29%; 38%), and decreased white blood cell count (0; 0; 14%; 25%). Six dose-limiting toxicities (DLTs) were observed in 4 pts at 400 mg in Reg 1A: G4 hypophosphatemia (n=2), G3 infection (n=1), G3 chronic graft versus host disease (n=1), G3 stomatitis (n=1), and G4 subarachnoid hemorrhage (n=1). One DLT each occurred in Reg 1B (G4 acute kidney injury at 150 mg) and Reg 2C (G4 TLS at 45 mg). Importantly, there were no dose-limiting gastrointestinal (GI) toxicities. NVP-HDM201 also showed approximate dose-proportional pharmacokinetics (PK) and pharmacodynamics.

Investigator-assessed overall response rate (CR + CRi + PR) for all pts with AML who had ≥1 post-baseline assessment (n=34) was 20.6% (95% confidence interval: 8.7-37.9%). There were 3 CRs (2 in Reg 1A; 1 in Reg 2C) and 4 CRis (1 in Reg 1B; 3 in Reg 2C). CRs/CRis were observed in pts receiving a cumulative dose of 250 mg within the first wk of treatment.

Conclusions: Across all regimens, the AEs reported were overall expected and manageable, with no dose-limiting GI toxicities. The recommended dose for expansion (RDE) was declared as 45 mg in Reg 2C, based on the manageable safety profile, therapeutically relevant exposures determined by PK modeling, and meaningful antitumor activity seen at this dose level of NVP-HDM201. RDE determination for Reg 1A and Reg 1B is ongoing. Preliminary anti-leukemic activity is promising in these pts and warrants further study of this agent in AML.

Citation Format: Eytan Stein, Joerg Chromik, Daniel J. DeAngelo, Manik Chatterjee, Richard Noppeney, Filip de Vos, Hironobu Minami, Sébastien Jeay, Christophe Meille, Ensar Halilovic, Luisa Mariconti, Matthieu Klopfenstein, Nelson Guerreiro, Rajkumar Radhakrishnan, Emil T. Kuriakose, Cecilia Carpio. Phase I dose- and regimen-finding study of NVP-HDM201 in pts with advanced TP53 wt acute leukemias [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT152. doi:10.1158/1538-7445.AM2017-CT152

Revisiting dosing regimen using PK/PD modeling: the MODEL1 phase I/II trial of docetaxel plus epirubicin in metastatic breast cancer patients

The MODEL1 trial is the first model-driven phase I/II dose-escalation study of densified docetaxel plus epirubicin administration in metastatic breast cancer patients, a regimen previously known to induce unacceptable life-threatening toxicities. The primary objective was to determine the maximum tolerated dose of this densified regimen. Study of the efficacy was a secondary objective. Her2-negative, hormone-resistant metastatic breast cancer patients were treated with escalating doses of docetaxel plus epirubicin every 2 weeks for six cycles with granulocyte colony stimulating factor support. A total of 16 patients were treated with total doses ranging from 85 to 110 mg of docetaxel plus epirubicin per cycle. Dose escalation was controlled by a non-hematological toxicity model. Dose densification was guided by a model of neutrophil kinetics, able to optimize docetaxel plus epirubicin dosing with respect to pre-defined acceptable levels of hematological toxicity while ensuring maximal efficacy. The densified treatment was safe since hematological toxicity was much lower compared to previous findings, and other adverse events were consistent with those observed with this regimen. The maximal tolerated dose was 100 mg given every 2 weeks. The response rate was 45 %; median progression-free survival was 10.4 months, whereas 54.6 months of median overall survival was achieved. The optimized docetaxel plus epirubicin dosing regimen led to fewer toxicities associated with higher efficacy as compared with standard or empirical densified dosing. This study suggests that model-driven dosage adjustment can lead to improved efficacy-toxicity balance in patients with cancer when several anticancer drugs are combined.

Metronomics chemotherapy: time for computational decision support

Over the last decade, metronomic chemotherapy has been increasingly considered as an attractive strategy for treating cancer in a variety of settings. Beside pharmaco-economic considerations making metronomics a unique opportunity in low- or middle-income countries, revisiting dosing schedules using continuous low doses of cytotoxics should theoretically permit to reduce the incidence of treatment-related toxicities, while offering unexpected novel mechanisms of actions such as antiangiogenic or immuno-stimulating properties. Consequently, a number of clinical trials sought to evaluate to what extent switching to metronomic schedules could actually impact indeed on the efficacy/toxicity balance of a variety of anticancer drugs in both adults and pediatric oncology. Vinorelbine is a vinca-alcaloïd that remains the backbone of several regimens to treat patients with metastatic breast cancer or non-small cell lung cancer. Additionally, vinorelbine is widely used to treat a variety of solid tumors in children such as rhabdomyosarcomas and acute leukemia. The recent approval of an oral formulation of vinorelbine has open the way to developing alternative metronomic schedules with this drug. Consequently, a number of clinical trials investigating on metronomic vinorelbine have been performed over the last few years, with seemingly inconsistent results to date. Of note, all the studies published thus far were based upon empirical determination of the metronomic schedule, both in terms of doses, drug-free intervals and repartition of the administrations throughout time. Because the very concept of «low, repeated doses with little or no drug-free interval» covers numerous possible combinations, determining the optimal protocol using traditional under-powered empirical design looks like an unreachable goal. In this context, mathematical modeling offers invaluable in silico tools to help determining the optimal metronomic schedule among a variety of possibilities. This review covers the latest clinical trials investigating on metronomic vinorelbine and proposes alternative strategies for developing computational decision support to make metronomics a scientific-grounded strategy, rather than an empirical practice at the bedside. In particular, mathematical simulations using an original pharmacokinetics/pharmacodynamics constraint models provide clues for exploring new paths in the way metronomic vinorelbine could be scheduled in patients with lung cancer.

Preclinical optimization of MDM2 antagonist scheduling for cancer treatment by using a model-based approach

PURPOSE

Antitumor clinical activity has been demonstrated for the MDM2 antagonist RG7112, but patient tolerability for the necessary daily dosing was poor. Here, utilizing RG7388, a second-generation nutlin with superior selectivity and potency, we determine the feasibility of intermittent dosing to guide the selection of initial phase I scheduling regimens.

EXPERIMENTAL DESIGN

A pharmacokinetic-pharmacodynamic (PKPD) model was developed on the basis of preclinical data to determine alternative dosing schedule requirements for optimal RG7388-induced antitumor activity. This PKPD model was used to investigate the pharmacokinetics of RG7388 linked to the time-course of the antitumor effect in an osteosarcoma xenograft model in mice. These data were used to prospectively predict intermittent and continuous dosing regimens, resulting in tumor stasis in the same model system.

RESULTS

RG7388-induced apoptosis was delayed relative to drug exposure with continuous treatment not required. In initial efficacy testing, daily dosing at 30 mg/kg and twice a week dosing at 50 mg/kg of RG7388 were statistically equivalent in our tumor model. In addition, weekly dosing of 50 mg/kg was equivalent to 10 mg/kg given daily. The implementation of modeling and simulation on these data suggested several possible intermittent clinical dosing schedules. Further preclinical analyses confirmed these schedules as viable options.

CONCLUSION

Besides chronic administration, antitumor activity can be achieved with intermittent schedules of RG7388, as predicted through modeling and simulation. These alternative regimens may potentially ameliorate tolerability issues seen with chronic administration of RG7112, while providing clinical benefit. Thus, both weekly (qw) and daily for five days (5 d on/23 off, qd) schedules were selected for RG7388 clinical testing.

Retrospective analysis of data from a phase I trial with a new adaptive method

1067

Background: The phase I trial CAPEV CGFL 01 [ESMO, Vienne, Austria: 2004.V 52–53] aimed to find the Maximum Tolerated Dose (MTD) of i.v. Vinorelbine when associated with oral Capecitabine for three cycles of 21 days in metastatic breast cancer (MBC). Method: Vinorelbine was administered at d1 and d15 and Capecitabine b.i.d. from d1 to d14 (fixed at 2,000 mg/m2/day). Trial design was based on “3+3” scheme with predetermined dose levels of Vinorelbine starting at 25 mg/m2/day. Ten patients (age 46–67 years) with MBC were enrolled in this trial. A new phase I adaptive method [Statistical Methods in Biopharmacy. Statistical Innovations in Clinical trials, Paris September 2005] under validation was used to analyze data available from the CAPEV trial. This method performs precise definition of Dose Limiting Toxicity (DLT) and modeling of all the grades of toxicity. The method allows sequential real time analysis of data by alternating estimation and design steps. Results: Most frequent toxicities were hematological (anemia and neutropenia) and cytolysis. Three DLTs occurred for the first 6 patients included at the starting level of Vinorelbine. De-escalation to 20 mg/m2 was done at the 7th patient but a new DLT occurred for the 7th patient and lead to trial ending at the 10th patient. Firstly, by analyzing all available data, Vinorelbine MTD was calculated at 20.2±4.04 mg/m2/day. Secondly, data was processed according to the inclusion time of patients; the adaptive method calculated a Vinorelbine MTD equal to 19.5±8.34 mg/m2/day as early as the 4th patient. Conclusion: The administration scheme of i.v. Vinorelbine and oral Capecitabine tried in this study cannot be retained for MBC treatment. However, early convergence of adaptive method clearly shows its high performance in the de-escalation scheme and Vinorelbine MTD determination. With this method Vinorelbine MTD could have been determined with the 4th patient data without needing the inclusion of 6 additional patients (4th and not 7th patient). This method should be used in prospective phase I trials and in parallel with classical and clinical method of MTD determination.

No significant financial relationships to disclose.

A mechanistic model predicting hematopoiesis and tumor growth to optimize docetaxel + epirubicin (ET) administration in metastatic breast cancer (MBC): Phase I trial

13013

Background: Mathematical modeling is a powerful approach to provide functional description of a real process. In medicine and biology, models are established on the basis of available clinical observations and biological covariates. Modeling applied in cancer treatment is a valuable tool to perform drug dosage adjustments. We used this methodology to regulate ET administration by predicting haematopoiesis and tumor growth in patients with MBC in a phase I trial. Methods: We developed a mechanistic model to describe leukopoiesis / thrombopoiesis / tumor growth in MBC patients under bimonthly ET + G-CSF. The model was first validated using data from clinical trials [Viens, Am J Clin Oncol. 2001;24:328, Chugai lenograstim database] and prospectively applied to individualize ET administration (dose rate and duration). The model optimizes the drug doses that could minimize the tumour burden while respecting a priori fixed constraints on deepness / duration of neutropenia and thrombocytopenia. First course administration was fixed ahead. At following courses, schedules were individually adjusted. At first dose level, patients received ET: 85/85 mg over a 48 h period with various, electronically- controlled infusion rates every 2 weeks. At dose level 2, doses were 100/100 mg. Results: Between 06/2005 and 06/2006, 3.5 median courses (range: 2–6) were administered to 6 patients (level 1: 3; level 2: 3). Rates of grade 3–4 neutropenia and thrombocytopenia were 47 and 0 % respectively. Observed toxicities were close to those predicted by the model. Predicted vs. observed neutrophil counts linear regression was significant (p<0.001). Moreover, 83 and 95 % weighted residuals were comprised between [-2; +2] at all courses and first course respectively. No grade 3–4 non-hematological toxicity was observed. Partial responses were noted in 2 patients (33%) and disease stabilization in 3 patients (50%). Conclusions: We report the preliminary results of the first trial using mechanistic modeling to improve cancer chemotherapy. Using this approach, we have successfully predicted the behavior of a complex biological system and individualized drugs administration in a phase I trial.

No significant financial relationships to disclose.

Taxanes in paediatric oncology: And now?

Taxanes are a group of anticancer agents that target microtubules, promote their assembly, and stabilize them. The resulting effects are mitotic blockage and induction of apoptosis, whose mechanism of initiation remains to be fully determined. Among adults, taxanes are one of the most powerful and most commonly used anticancer drugs. They show a wide range of activity in malignancies such as breast, ovarian, and lung cancers. In paediatric oncology, pre-clinical and clinical data are quite limited. Six phase I studies, two phase II, and rare case reports have been published. This review will focus on the paediatric pre-clinical and clinical findings with taxanes. Based on data from the literature, we will try to explain the results and foresee the possible use of taxanes in paediatric oncology. Indeed, three main advances have been made regarding taxanes: (1) Increased efficacy when used in multidrug-based chemotherapy regimen. (2) New administration schedules based on anti-angiogenic properties when given at daily very low doses. (3) Development of new taxanes with decreased recognition by Pgp, the product of the MDR1 gene. Thus, although the initial experience with taxanes in paediatric oncology has been disappointing, it may be too early to leave out taxanes and we should further investigate their use among children with cancer.