Tumor dynamics in patients with solid tumors treated with pembrolizumab beyond disease progression.

While many patients are treated beyond progression (TBP), the magnitude and duration of clinical benefit in these patients have not been fully quantified. Data from 799 patients with melanoma (n = 176), non-small cell lung cancer (NSCLC; n = 146), gastric cancer (GC; n = 87), head and neck squamous cell carcinoma (HNSCC; n = 112), clear-cell renal cell carcinoma (ccRCC; n = 51), and urothelial carcinoma (UC; n = 227) TBP were included. Patients had received pembrolizumab beyond confirmed progressive disease (PD) per RECIST v1.1. A subset of patients displays a 30% reduction in the sum of lesion diameters in the post-progression period (melanoma 24.4%, NSCLC 11.6%, 12.6% GC, 8.9% HNSCC, 15.7% ccRCC, and 13.2% UC). Most patients show stable target lesion dynamics in the post-progression period (melanoma, 64.8%; NSCLC, 72.6%; GC, 69.0%, 75.9% HNSCC, 72.5% ccRCC, 75.3% UC). Pembrolizumab generates meaningful efficacy in a subset of patients treated beyond RECIST v1.1 progression.

Population pharmacokinetic analyses for belzutifan to inform dosing considerations and labeling.

Belzutifan (Welireg, Merck & Co., Inc., Rahway, NJ, USA) is an oral, potent inhibitor of hypoxia-inducible factor 2α, approved for the treatment of certain patients with von Hippel-Lindau (VHL) disease-associated renal cell carcinoma (RCC), central nervous system hemangioblastomas, and pancreatic neuroendocrine tumors. It is primarily metabolized by the polymorphic uridine 5'-diphospho-glucuronosyltransferase (UGT) 2B17 and cytochrome (CYP) 2C19. A population pharmacokinetic (PK) model was built, using NONMEM version 7.3, based on demographics/PK data from three clinical pharmacology (food effect, formulation bridging, and genotype/race effect) and two clinical studies (phase I dose escalation/expansion in patients with RCC and other solid tumors; phase II in patients with VHL). Median (range) age for the combined studies was 55 years (19-84) and body weight was 73.6 kg (42.1-165.8). Belzutifan plasma PK was well-characterized by a linear two-compartment model with first-order absorption and elimination. For patients with VHL, the predicted geometric mean (% coefficient of variation) apparent clearance was 7.3 L/h (51%), apparent total volume of distribution was 130 L (35%), and half-life was 12.39 h (42%). There were no clinically relevant differences in belzutifan PK based on the individual covariates of age, sex, ethnicity, race, body weight, mild/moderate renal impairment, or mild hepatic impairment. In this model, dual UGT2B17 and CYP2C19 poor metabolizers (PMs) were estimated to have a 3.2-fold higher area under the plasma concentration-time curve compared to UGT2B17 extensive metabolizer and CYP2C19 non-PM patients. This population PK analysis enabled an integrated assessment of PK characteristics with covariate effects in the overall population and subpopulations for belzutifan labeling.

Pivotal Dose of Pembrolizumab: A Dose-Finding Strategy for Immuno-Oncology.

Despite numerous publications emphasizing the value of dose finding, drug development in oncology is dominated by the mindset that higher dose provides higher efficacy. Examples of dose finding implemented by biopharmaceutical firms can change this mindset. The purpose of this article is to outline a pragmatic dose selection strategy for immuno-oncology (IO) and other targeted monoclonal antibodies (mAbs). The approach was implemented for pembrolizumab. Selecting a recommended phase II dose (RP2D) with a novel mechanism of action is often challenging due to uncertain relationships between pharmacodynamics measurements and clinical end points. Additionally, phase I efficacy and safety data are generally inadequate for RP2D selection for IO mAbs. Here, the RP2D was estimated based on phase I (clinical study KN001 A and A2) pharmacokinetics data as the dose required for target saturation, which represents a surrogate for maximal pharmacological effect for antagonist mAbs. Due to limitations associated with collecting and analyzing tumor biopsies, characterizing intratumoral target engagement (TE) is challenging. To overcome this gap, a physiologically-based pharmacokinetic model was implemented to predict intratumoral TE. As tumors are spatially heterogeneous, TE was predicted in well-vascularized and poorly vascularized tumor regions. Additionally, impact of differences in target expression, for example, due to interindividual variability and cancer type, was simulated. Simulations showed that 200 mg every 3 weeks can achieve ≥ 90% TE in clinically relevant scenarios, resulting in the recommendation of 200 mg every 3 weeks as the RP2D. Randomized dose comparison studies (KN001 B2 and D) showing similar efficacy over a fivefold dose/exposure range confirmed the RP2D as the pivotal dose.

Experimental Medicine Study to Measure Immune Checkpoint Receptors PD-1 and GITR Turnover Rates In Vivo in Humans.

Development of monoclonal antibodies (mAbs) targeting immune-checkpoint receptors (IMRs) for the treatment of cancer is one of the most active areas of investment in the biopharmaceutical industry. A key decision in the clinical development of anti-IMR mAbs is dose selection. Dose selection can be challenging because the traditional oncology paradigm of administering the maximum tolerated dose is not applicable to anti-IMR mAbs. Instead, dose selection should be informed by the pharmacology of immune signaling. Engaging an IMR is a key initial step to triggering pharmacologic effects, and turnover (i.e., the rate of protein synthesis) of the IMR is a key property to determining the dose level needed to engage the IMR. Here, we applied the stable isotope labeling mass spectrometry technique using 13 C6 -leucine to measure the in vivo turnover rates of IMRs in humans. The 13 C6 -leucine was administered to 10 study participants over 15 hours to measure 13 C6 -leucine enrichment kinetics in 2 IMR targets that have been clinically pursued in oncology: GITR and PD-1. We report the first measurements of GITR and PD-1 median half-lives associated with turnover to be 55.6 and ≥ 49.5 hours, respectively. The approach outlined here can be applied to other IMRs and, more generally, to protein targets.

A six-weekly dosing schedule for pembrolizumab in patients with cancer based on evaluation using modelling and simulation.

BACKGROUND: Pembrolizumab is approved for multiple cancer types at 200 mg and 2 mg/kg dose every 3 weeks (Q3W). We used a model-based approach to compare the exposure of pembrolizumab 400 mg dose every 6 weeks (Q6W) with the Q3W regimens. METHODS: The Q6W dose was selected by matching exposure with the 200 mg and 2 mg/kg Q3W doses. Concentration-time profiles were simulated using the established population pharmacokinetic model of pembrolizumab based on 2993 subjects from five clinical trials across tumour types. Efficacy was bridged by evaluating projections of average concentration over the dosing interval (Cavg) and trough concentration (Cmin) at steady state (ss). Safety was bridged by ensuring that concentrations were below those at 10 mg/kg dose every 2 weeks (Q2W), the maximum clinical dose. RESULTS: The 400 mg Q6W dose had similar predicted exposure (Cavg,ss, geometric mean âˆ¼1% higher) as the 200 mg Q3W dose. Fewer than 1% of subjects had transiently lower Cmin,ss than that observed for 200 mg and 2 mg/kg Q3W. Despite these reductions, similar target saturation is expected. The predicted peak concentrations (Cmax,ss) for 400 mg Q6W were substantially (∼65%) lower than the 10 mg/kg Q2W dose. CONCLUSIONS: Exposures expected for pembrolizumab 400 mg Q6W were similar to the 200 mg and 2 mg/kg Q3W and below the 10 mg/kg Q2W regimens. Established exposure-response relationships for pembrolizumab over a 5-fold dose range (2 mg/kg Q3W to 10 mg Q2W) support that clinical efficacy and safety of 400 mg Q6W would be similar to the 200 mg and 2 mg/kg Q3W doses across tumour types. CLINICAL TRIAL REGISTRATION NUMBERS: NCT01295827, NCT01704287, NCT01866319, NCT01905657, NCT02142738.

Progress and Opportunities to Advance Clinical Cancer Therapeutics Using Tumor Dynamic Models.

There is a need for new approaches and endpoints in oncology drug development, particularly with the advent of immunotherapies and the multiple drug combinations under investigation. Tumor dynamics modeling, a key component to oncology "model-informed drug development," has shown a growing number of applications and a broader adoption by drug developers and regulatory agencies in the past years to support drug development and approval in a variety of ways. Tumor dynamics modeling is also being investigated in personalized cancer therapy approaches. These models and applications are reviewed and discussed, as well as the limitations and issues open for further investigations. A close collaboration between stakeholders like clinical investigators, statisticians, and pharmacometricians is warranted to advance clinical cancer therapeutics.

Model Informed Drug Development: Novel Oncology Agents are Lost in Translation.

Excitement around and investment in oncology drug development are at unprecedented levels. To maximize the health impact and productivity of this research and development investment, quantitative modeling should impact key decisions in early clinical oncology including Go/No-Go decisions based on early clinical data, and dose selection for late stage studies.See related article by Bottino et al., p. 6633.

Pembrolizumab Exposure-Response Assessments Challenged by Association of Cancer Cachexia and Catabolic Clearance.

PURPOSE: To investigate the relationship of pembrolizumab pharmacokinetics (PK) and overall survival (OS) in patients with advanced melanoma and non-small cell lung cancer (NSCLC). PATIENTS AND METHODS: PK dependencies in OS were evaluated across three pembrolizumab studies of either 200 mg or 2 to 10 mg/kg every 3 weeks (Q3W). Kaplan-Meier plots of OS, stratified by dose, exposure, and baseline clearance (CL0), were assessed per indication and study. A Cox proportional hazards model was implemented to explore imbalances of typical prognostic factors in high/low NSCLC CL0 subgroups. RESULTS: A total of 1,453 subjects were included: 340 with pembrolizumab-treated melanoma, 804 with pembrolizumab-treated NSCLC, and 309 with docetaxel-treated NSCLC. OS was dose independent from 2 to 10 mg/kg for pembrolizumab-treated melanoma [HR = 0.98; 95% confidence interval (CI), 0.94-1.02] and NSCLC (HR = 0.98; 95% CI, 0.95-1.01); however, a strong CL0-OS association was identified for both cancer types (unadjusted melanoma HR = 2.56; 95% CI, 1.72-3.80 and NSCLC HR = 2.64; 95% CI, 1.94-3.57). Decreased OS in subjects with higher pembrolizumab CL0 paralleled disease severity markers associated with end-stage cancer anorexia-cachexia syndrome. Correction for baseline prognostic factors did not fully attenuate the CL0-OS association (multivariate-adjusted CL0 HR = 1.64; 95% CI, 1.06-2.52 for melanoma and HR = 1.88; 95% CI, 1.22-2.89 for NSCLC). CONCLUSIONS: These data support the lack of dose or exposure dependency in pembrolizumab OS for melanoma and NSCLC between 2 and 10 mg/kg. An association of pembrolizumab CL0 with OS potentially reflects catabolic activity as a marker of disease severity versus a direct PK-related impact of pembrolizumab on efficacy. Similar data from other trials suggest such patterns of exposure-response confounding may be a broader phenomenon generalizable to antineoplastic mAbs.See related commentary by Coss et al., p. 5787.

Baseline Tumor Size Is an Independent Prognostic Factor for Overall Survival in Patients with Melanoma Treated with Pembrolizumab.

Purpose: The purpose of this study was to assess the association of baseline tumor size (BTS) with other baseline clinical factors and outcomes in pembrolizumab-treated patients with advanced melanoma in KEYNOTE-001 (NCT01295827).Experimental Design: BTS was quantified by adding the sum of the longest dimensions of all measurable baseline target lesions. BTS as a dichotomous and continuous variable was evaluated with other baseline factors using logistic regression for objective response rate (ORR) and Cox regression for overall survival (OS). Nominal P values with no multiplicity adjustment describe the strength of observed associations.Results: Per central review by RECIST v1.1, 583 of 655 patients had baseline measurable disease and were included in this post hoc analysis. Median BTS was 10.2 cm (range, 1-89.5). Larger median BTS was associated with Eastern Cooperative Oncology Group performance status 1, elevated lactate dehydrogenase (LDH), stage M1c disease, and liver metastases (with or without any other sites; all P ≤ 0.001). In univariate analyses, BTS below the median was associated with higher ORR (44% vs. 23%; P < 0.001) and improved OS (HR, 0.38; P < 0.001). In multivariate analyses, BTS below the median remained an independent prognostic marker of OS (P < 0.001) but not ORR. In 459 patients with available tumor programmed death ligand 1 (PD-L1) expression, BTS below the median and PD-L1-positive tumors were independently associated with higher ORR and longer OS.Conclusions: BTS is associated with many other baseline clinical factors but is also independently prognostic of survival in pembrolizumab-treated patients with advanced melanoma. Clin Cancer Res; 24(20); 4960-7. ©2018 AACR See related commentary by Warner and Postow, p. 4915.

Rendering the 3 + 3 Design to Rest: More Efficient Approaches to Oncology Dose-Finding Trials in the Era of Targeted Therapy.

Selection of the maximum tolerated dose (MTD) as the recommended dose for registration trials based on a dose-escalation trial using variations of an MTD/3 + 3 design often occurs in the development of oncology products. The MTD/3 + 3 approach is not optimal and may result in recommended doses that are unacceptably toxic for many patients and in dose reduction/interruptions that might have an impact on effectiveness. Instead of the MTD/3 + 3 approach, the authors recommend an integrated approach. In this approach, typically an adaptive/Bayesian model provides a general framework to incorporate and make decisions for dose escalation based on nonclinical data, such as animal efficacy and toxicity data; clinical data, including pharmacokinetics/pharmacodynamics data; and dose/exposure-response data for efficacy and safety. To improve dose-ranging trials, model-based estimation, rather than hypothesis testing, should be used to maximize and integrate the information gathered across trials and doses. This approach may improve identification of optimal recommended doses, which can then be confirmed in registration trials. Clin Cancer Res; 22(11); 2623-9. ©2016 AACR SEE ALL ARTICLES IN THIS CCR FOCUS SECTION, "NEW APPROACHES FOR OPTIMIZING DOSING OF ANTICANCER AGENTS".

Optimal Dosing for Targeted Therapies in Oncology: Drug Development Cases Leading by Example.

One of the key objectives of oncology first-in-human trials has often been to establish the maximum tolerated dose (MTD). However, targeted therapies might not exhibit dose-limiting toxicities (DLT) at doses significantly higher than sufficiently active doses, and there is frequently a limited ability to objectively quantify adverse events. Thus, while MTD-based determination of recommended phase II dose may have yielded appropriate dosing for some cytotoxics, targeted therapeutics (including monoclonal antibodies and/or immunotherapies) sometimes need alternative or complementary strategies to help identify dose ranges for a randomized dose-ranging study. One complementary strategy is to define a biologically efficacious dose (BED) using an "effect marker." An effect marker could be a target engagement, pharmacodynamic, or disease progression marker (change in tumor size for solid tumors or bone marrow blast count for some hematologic tumors). Although the concept of BED has been discussed extensively, we review specific examples in which the approach influenced oncology clinical development. Data extracted from the literature and the examples support improving dose selection strategies to benefit patients, providers, and the biopharmaceutical industry. Although the examples illustrate key contributions of effect markers in dose selection, no one-size-fits-all approach to dosing can be justified. Higher-than-optimal dosing can increase toxicity in later trials (and in clinical use), which can have a negative impact on efficacy (via lower adherence or direct sequelae of toxicities). Proper dose selection in oncology should follow a multifactorial decision process leading to a randomized, dose-ranging study instead of a single phase II dose.

A phase II study of tasisulam sodium (LY573636 sodium) as second-line or third-line treatment for patients with unresectable or metastatic soft tissue sarcoma.

BACKGROUND: Tasisulam sodium (hereafter tasisulam), a novel anticancer agent, is being studied in a broad range of tumors. The primary objective of this phase II study was to determine progression-free survival (PFS) in patients with 1 or 2 prior chemotherapy regimens for unresectable/metastatic soft tissue sarcoma (STS). Secondary objectives included objective response rate (ORR), clinical benefit rate (CBR), overall survival (OS), pharmacokinetics, and safety. METHODS: Tasisulam was administered intravenously on day 1 of 21-day cycles according to a lean body weight-based dosing algorithm targeting a peak plasma concentration (C(max)) of 420 µg/mL; a 360-µg/mL dose level was also explored. RESULTS: The median age of patients treated at 420 µg/mL was 58.3 years (range, 18.6-80.4; n = 63). Median PFS was 2.64 months (90 % CI, 1.41-3.38), with a 6-month PFS rate of 11 % (90 % CI, 4-17). Median OS was 8.71 months (90 % CI, 7.39-16.23); ORR, 3.2 %; and CBR, 46.0 % (stable disease, n = 27; partial response/confirmed, n = 2 [angiosarcoma and leiomyosarcoma]; partial response/unconfirmed, n = 1 [desmoplastic small round cell tumor]). The most frequent drug-related grade 3/4 toxicities in patients treated at 420 µg/mL were thrombocytopenia (27.0 %) and neutropenia (22.2 %). Incidences of grade 4 thrombocytopenia and/or neutropenia were 20.6 % in patients treated at 420 µg/mL and 15.8 % in those treated at 360 µg/mL (n = 38). CONCLUSIONS: Tasisulam at a target C(max) of 420 µg/mL on day 1 of 21-day cycles demonstrated modest activity as second-/third-line treatment in patients with STS. Grade 4 hematologic toxicity posed some challenges in these heavily pre-treated patients. Tasisulam dosing continues to be refined.

A phase I study of tasisulam sodium (LY573636 sodium), a novel anticancer compound, administered as a 24-h continuous infusion in patients with advanced solid tumors.

PURPOSE: To determine the recommended/maximum tolerated dose (MTD), pharmacokinetics (PK), and safety profile of tasisulam sodium (hereafter tasisulam), a novel anticancer agent. METHODS: In this phase I study, tasisulam was administered as a 24-h continuous intravenous infusion on day 1, every 28 days, to patients with advanced solid tumors. A flat-dosing schema was planned for four cohorts of 3-6 patients: 600, 1,200, 2,000, and 2,500 mg. RESULTS: Twenty-six patients were enrolled. No dose-limiting toxicities (DLTs) were observed until cohort 3 (grade 3 hyperbilirubinemia). Interim PK analyses of this and another ongoing phase I study suggested that a lower dose after cycle 1 was necessary for doses ≥2,500 mg because of the long half-life of tasisulam (~14 days). Therefore, a loading dose of 2,500 mg followed by a chronic dose of 1,750 mg was implemented for cohort 4; one patient developed DLT (grade 4 neutropenia), and another developed grade 3 thrombocytopenia in cycles 2 and 3. These findings, together with PK data, which indicated a disproportionate increase in free drug relative to total tasisulam concentrations at doses >2,500 mg, led to the determination of the 2,500-/1,750-mg regimen as the MTD. Eight patients had stable disease, and two patients unconfirmed partial responses. CONCLUSIONS: When administered as a flat-dose, 24-h infusion, the MTD of tasisulam was a loading dose of 2,500 mg followed by a chronic dose of 1,750 mg, every 28 days. Consistent with the profile of the 2-h infusion in clinical development, bone marrow suppression was the major DLT.

Tasisulam sodium (LY573636 sodium) as third-line treatment in patients with unresectable, metastatic non-small-cell lung cancer: a phase-II study.

INTRODUCTION: Tasisulam sodium (hereafter referred to as tasisulam) is a novel anticancer compound that induces apoptosis and exhibits antiangiogenesis activity in a broad range of cancer models, including non-small-cell lung cancer (NSCLC). METHODS: Tasisulam was administered as a 2-hour infusion every 21 days as third-line treatment in patients with advanced (stage IIIB/IV) NSCLC. RESULTS: Thirty-two patients received a Cmax target dose of 420 µg/ml. Median time to progression was 3.12 months, median progression-free survival was 2.69 months, and median overall survival was 8.48 months. There were no objective responses; 43.8% of patients achieved stable disease. A high rate of grade-4 hematologic toxicity in the first 30 patients led to exploration of a lower Cmax target dose of 380 µg/ml. The rate of grade-4 hematologic toxicity (thrombocytopenia and/or neutropenia) at the 380-µg/ml dose (n = 20) was 20% versus 34% at the 420-µg/ml dose. CONCLUSIONS: Tasisulam has only modest activity as a third-line treatment of patients with unresectable/metastatic NSCLC. The high rate of grade-4 hematologic toxicity observed with this highly albumin- bound compound in this patient population provided challenges for fixed Cmax-based dosing. Alternative dosing methods, including varying the Cmax target dose by predose albumin, are under investigation in other studies.

A phase 2 study of tasisulam sodium (LY573636 sodium) as second-line treatment for patients with unresectable or metastatic melanoma.

BACKGROUND: Tasisulam sodium (hereafter, tasisulam) is a novel anticancer agent that induces apoptosis through the intrinsic pathway and has antiangiogenic activity in preclinical models. Tasisulam demonstrated activity across a broad range of tumors, including melanoma. The primary objective of this phase 2 study was to determine the objective response rate (ORR) in patients who had received 1 previous systemic chemotherapy for unresectable/metastatic melanoma; secondary objectives were to evaluate the clinical response rate (CRR), progression-free survival (PFS), overall survival (OS), duration of response, safety, and pharmacokinetics. METHODS: Tasisulam was administered intravenously on Day 1 of 21-day cycles according to a lean body weight-based dosing algorithm targeting a peak plasma concentration (C(max)) of 420 µg/mL. RESULTS: In 68 enrolled patients, the median age was 59 years (range, 26-83 years). No patients had a complete response (CR), 8 patients had a partial response (PR), and 24 patients had stable disease (SD); the ORR (CR + PR) was 11.8%, and the CRR (CR + PR + SD) was 47.1%. The median PFS was 2.6 months, and the median OS was 9.6 months. The predominant treatment-related grade 3/4 toxicity was thrombocytopenia (20.6% of patients). Tasisulam exhibited a biexponential disposition with a predicted distribution half-life of 0.3 hours to 2.8 hours and a median terminal elimination half-life of 10 days (consistent with the turnover of albumin), suggesting that tasisulam is very tightly bound to albumin. CONCLUSIONS: Tasisulam administered at a targeted C(max) of 420 µg/mL on Day 1 of 21-day cycles demonstrated activity and tolerable toxicity as second-line treatment in malignant melanoma. These results led to a registration trial in metastatic melanoma.

A phase I study of tasisulam sodium (LY573636 sodium), a novel anticancer compound in patients with refractory solid tumors.

PURPOSE: This phase I study was carried out to determine the phase II recommended dose of tasisulam sodium (hereafter, tasisulam), a novel anticancer agent with a unique mechanism of action. METHODS: Tasisulam was administered intravenously, every 21 days, in patients with refractory solid tumors using a three-plus-three dose-escalation schema. RESULTS: Fifty-three patients were enrolled; the first 34 were treated with a flat dose of tasisulam of up to 2,400 mg, the dose level at which all three patients had dose-limiting toxicity (DLT). Controlling for C(max) proved important to reduce the risk of toxicity; therefore, we initially focused on identifying which parameters explained C(max) (end-of-infusion concentration) variability. Pharmacokinetic analysis indicated that C(max) negatively correlates with lean body weight (LBW). Thus, the dosing regimen was revised using a LBW-based algorithm targeting a specific C(max). A loading/chronic dose paradigm was then implemented as pharmacokinetic results revealed a long terminal half-life of tasisulam, likely because of its high-affinity albumin binding. C(max)-based dose escalation was stopped at the 420-µg/mL cohort, in which one of the 16 patients had DLT (transient hepatic transaminase elevation); grade 3/4 hematologic toxicity was noted in later cycles in three patients. Although response was not a primary objective, 33% of heavily pretreated patients with post-dose radiological assessments had stable disease. CONCLUSION: Implementation of a novel targeted C(max)-based dosing regimen allowed for the recommendation of a phase II tasisulam dose (loading dose of 420 µg/mL targeted C(max) with all subsequent doses administered at 65% of chronic dose given every 21 days) despite pharmacological challenges posed by high albumin binding.

Modelling the genesis and treatment of cancer: the potential role of physiologically based pharmacodynamics.

Physiologically based modelling of pharmacodynamics/toxicodynamics requires an a priori knowledge on the underlying mechanisms causing toxicity or causing the disease. In the context of cancer, the objective of the expert meeting was to discuss the molecular understanding of the disease, modelling approaches used so far to describe the process, preclinical models of cancer treatment and to evaluate modelling approaches developed based on improved knowledge. Molecular events in cancerogenesis can be detected using 'omics' technology, a tool applied in experimental carcinogenesis, but also for diagnostics and prognosis. The molecular understanding forms the basis for new drugs, for example targeting protein kinases specifically expressed in cancer. At present, empirical preclinical models of tumour growth are in great use as the development of physiological models is cost and resource intensive. Although a major challenge in PKPD modelling in oncology patients is the complexity of the system, based in part on preclinical models, successful models have been constructed describing the mechanism of action and providing a tool to establish levels of biomarker associated with efficacy and assisting in defining biologically effective dose range selection for first dose in man. To follow the concentration in the tumour compartment enables to link kinetics and dynamics. In order to obtain a reliable model of tumour growth dynamics and drug effects, specific aspects of the modelling of the concentration-effect relationship in cancer treatment that need to be accounted for include: the physiological/circadian rhythms of the cell cycle; the treatment with combinations and the need to optimally choose appropriate combinations of the multiple agents to study; and the schedule dependence of the response in the clinical situation.