Phase I oncology studies: evidence that in the era of targeted therapies patients on lower doses do not fare worse

The Right Dose: Results of a Patient Advocate-Led Survey of Individuals With Metastatic Breast Cancer Regarding Treatment-Related Side Effects and Views About Dosage Assessment to Optimize Quality of Life

PURPOSE

Although patients with metastatic breast cancer (MBC) have been living longer with the advent of more effective treatments such as targeted therapy and immunotherapy, the disease remains incurable, and most patients will undergo therapy indefinitely. When beginning therapy, patients are typically prescribed dose often based upon the maximum tolerated dose identified in phase I clinical trials. However, patients' perspectives about tolerability and willingness to discuss individualized dosing of drugs upon initiation of a new regimen and throughout the course of treatment have not been comprehensively evaluated.

METHODS

Patient advocates and medical oncologists from the Patient-Centered Dosing Initiative (PCDI) developed a survey to ascertain the prevalence and severity of MBC patients' treatment-related side effects, the level of patient-physician communication, mitigation strategies, perception about the relative efficacy of higher versus lower doses, and willingness to discuss alternative dosing. The PCDI distributed the anonymous confidential online survey in August 2020 to individuals with self-reported MBC.

RESULTS

One thousand and two hundred twenty-one patients with MBC completed the survey. 86.1% (n = 1,051) reported experiencing at least one significant treatment-related side effect, and of these, 20.3% (n = 213) visited the emergency room/hospital and 43.2% (n = 454) missed at least one treatment. Nearly all patients with side effects (97.6%, n = 1,026) informed their doctor and 81.7% (n = 838) received assistance. Of the 556 patients given a dose reduction for side-effect mitigation, 82.6% (n = 459) reported relief. Notably, majority of patients (53.3%, n = 651) do not believe that higher dose is always more effective than lower dose, and 92.3% (n = 1,127) would be willing to discuss flexible dosing options with their physicians based upon personal characteristics to optimize quality of life.

CONCLUSION

Given that the majority of patients with MBC experienced at least one substantial treatment-related side effect and most patients given a dose reduction reported improvement, innovative dosage-related strategies are warranted to sustain and improve patients' well-being. Patient-physician discussions in which the patient's unique attributes and circumstances are assessed upon initiation of new treatment and throughout the course of therapy may facilitate the identification of the most favorable dose for each patient, and the majority of patients would be receptive to this approach.

Advancing cancer drug development with mechanistic mathematical modeling: bridging the gap between theory and practice

Quantitative predictive modeling of cancer growth, progression, and individual response to therapy is a rapidly growing field. Researchers from mathematical modeling, systems biology, pharmaceutical industry, and regulatory bodies, are collaboratively working on predictive models that could be applied for drug development and, ultimately, the clinical management of cancer patients. A plethora of modeling paradigms and approaches have emerged, making it challenging to compile a comprehensive review across all subdisciplines. It is therefore critical to gauge fundamental design aspects against requirements, and weigh opportunities and limitations of the different model types. In this review, we discuss three fundamental types of cancer models: space-structured models, ecological models, and immune system focused models. For each type, it is our goal to illustrate which mechanisms contribute to variability and heterogeneity in cancer growth and response, so that the appropriate architecture and complexity of a new model becomes clearer. We present the main features addressed by each of the three exemplary modeling types through a subjective collection of literature and illustrative exercises to facilitate inspiration and exchange, with a focus on providing a didactic rather than exhaustive overview. We close by imagining a future multi-scale model design to impact critical decisions in oncology drug development.

Association of Selinexor Dose Reductions With Clinical Outcomes in the BOSTON Study

BACKGROUND

Dose modifications in response to adverse events (AEs) can maintain tumor response and improve therapy tolerability. We conducted a post-hoc analysis of the efficacy and safety of reduced selinexor doses in the BOSTON trial (NCT03110562).

PATIENTS AND METHODS

Efficacy, safety, and quality of life (QoL) in 195 patients with relapsed/refractory multiple myeloma randomized to once-weekly (QW) selinexor (100 mg), QW subcutaneous bortezomib (1.3 mg/m2), and twice-weekly dexamethasone (20 mg) were compared between patients with dose reductions and those without.

RESULTS

In total, 126 patients (65%) had selinexor dose reductions (median dose 71.4 mg/wk). In patients with dose reductions versus those without median progression-free survival was 16.6 months (95% CI 12.9-not evaluable [NE]) versus 9.2 months [95% CI 6.8-15.5]), overall response rate was 81.7% (95% CI 73.9-88.1%) versus 66.7% (95% CI 54.3-77.6%), ≥very good partial response was (51.6% [95% CI 42.5-60.6%] vs. 31.9% [95% CI 21.2-44.2]), median duration of response was not reached (95% CI 13.8-NE) versus 12.0 months (95% CI 8.3-NE), and time to next treatment was 22.6 months (95% CI 14.6-NE) versus 10.5 months (95% CI 6.3-18.2). Mean best change from baseline on the EORTC QLQ-C30 Global Health Status/QoL scale was 10.0 ± 20.5 versus 4.0 ± 20.9. Duration-adjusted AE rates that were lower after selinexor dose reduction included thrombocytopenia (62.5% before vs. 47.6% after), nausea (31.6% vs. 7.3%), fatigue (28.1% vs. 9.9%), decreased appetite (21.5% vs. 6.4%), anemia (17.9% vs. 10.3%), and diarrhea (12.9% vs. 5.2%).

CONCLUSION

Appropriate dose reductions in response to AEs of the 100 mg selinexor starting dose in the BOSTON study were associated with improved efficacy, reduced AE rates and improved QoL.

At the right dose: personalised (N-of-1) dosing for precision oncology

The objective of oncology therapeutics, especially in the age of precision medicine, is to give the right drug(s) to the right patient at the right time. Yet, a major challenge is finding the right dose for each patient. Determining safe and efficacious doses of oncology treatments, especially for novel combination therapies, can be challenging. Moreover, traditionally, dosing cancer drugs is based on giving each patient the same dose (a flat dose) or a dose based on surface area/weight. But patients' ability to tolerate drugs is influenced by additional factors including, but not limited to age, gender, race, comorbidities, organ function, and metabolism. Herein, we present evidence that, in the era of targeted drugs, individualised drug dosing determined by starting at reduced doses and using intrapatient dose escalation can yield safe and effective personalised dosing of novel combinations of approved drugs that have not previously undergone formal phase I trials and can also optimise dosing of tested drug regimens.

Skipping a pillar does not make for strong foundations: Pharmacokinetic-pharmacodynamic reasoning behind the shape of dose-response relationships in oncology

Dose-response analysis is often applied to the quantification of drug-effect especially for slowly responding disease end points where a comparison is made across dose levels after a particular period of treatment. It has long been recognized that exposure - response is more appropriate than dose-response. However, trials necessarily are designed as dose-response experiments. Second, a wide range of functional forms are used to express relationships between dose and response. These considerations are also important for clinical development because pharmacokinetic (PK; and variability) plus pharmacokinetic-pharmacodynamic modeling may allow one to anticipate the shape of the dose-response curve and so the trial design. Here, we describe how the location and steepness of the dose response is determined by the PKs of the compound being tested and its exposure-response relationship in terms of potency (location), efficacy (maximum effect) and Hill coefficient (steepness). Thus, the location (50% effective dose [ED50 ]) is dependent not only on the potency (half-maximal effective concentration) but also the compound's PKs. Similarly, the steepness of the dose response is shown to be a function of the half-life of the drug. It is also shown that the shape of relationship varies dependent on the assumed time course of the disease. This is important in the context of drug-discovery where the in vivo potencies of compounds are compared as well as when considering an analysis of summary data (for example, model-based meta-analysis) for clinical decision making.

Clinical outcome assessment trends in clinical trials-Contrasting oncology and non-oncology trials

BACKGROUND

Clinical outcome assessments (COAs) are key to patient-centered evaluation of novel interventions and supportive care. COAs are particularly informative in oncology where a focus on how patients feel and function is paramount, but their incorporation in trial outcomes have lagged that of traditional survival and tumor responses. To understand the trends of COA use in oncology and the impact of landmark efforts to promote COA use, we computationally surveyed oncology clinical trials in ClinicalTrials.gov comparing them to the rest of the clinical research landscape.

METHODS

Oncology trials were identified using medical subject heading neoplasm terms. Trials were searched for COA instrument names obtained from PROQOLID. Regression analyses assessed chronological and design-related trends.

RESULTS

Eighteen percent of oncology interventional trials initiated 1985-2020 (N = 35,415) reported using one or more of 655 COA instruments. Eighty-four percent of the COA-using trials utilized patient-reported outcomes, with other COA categories used in 4-27% of these trials. Likelihood of COA use increased with progressing trial phase (OR = 1.30, p < 0.001), randomization (OR = 2.32, p < 0.001), use of data monitoring committees (OR = 1.26, p < 0.001), study of non-FDA-regulated interventions (OR = 1.23, p = 0.001), and in supportive care versus treatment-focused trials (OR = 2.94, p < 0.001). Twenty-six percent of non-oncology trials initiated 1985-2020 (N = 244,440) reported COA use; they had similar COA-use predictive factors as oncology trials. COA use increased linearly over time (R = 0.98, p < 0.001), with significant increases following several individual regulatory events.

CONCLUSION

While COA use across clinical research has increased over time, there remains a need to further promote COA use particularly in early phase and treatment-focused oncology trials.

Patient-centered dosing: oncologists' perspectives about treatment-related side effects and individualized dosing for patients with metastatic breast cancer (MBC)

PURPOSE

Although metastatic breast cancer (MBC) is treatable, it is not curable and most patients remain on treatment indefinitely. While oncologists commonly prescribe the recommended starting dose (RSD) from the FDA-approved label, patient tolerance may differ from that seen in clinical trials. We report on a survey of medical oncologists' perspectives about treatment-related toxicity and willingness to discuss flexible dosing with patients.

METHODS

We disseminated a confidential survey via social media/email in Spring 2021. Eligible respondents needed to be US-based medical oncologists with experience treating patients with MBC.

RESULTS

Of 131 responses, 119 were eligible. Physicians estimated that 47% of their patients reported distressing treatment-related side effects; of these, 15% visited the Emergency Room/hospital and 37% missed treatment. 74% (n = 87) of doctors reported improvement of patient symptoms after dose reduction. 87% (n = 104) indicated that they had ever, if appropriate, initiated treatment at lower doses. Most (85%, n = 101) respondents did not believe that the RSD is always more effective than a lower dose and 97% (n = 115) were willing to discuss individualized dosing with patients.

CONCLUSION

Treatment-related side effects are prevalent among patients with MBC, resulting in missed treatments and acute care visits. To help patients tolerate treatment, oncologists may decrease initial and/or subsequent doses. The majority of oncologists reject the premise that a higher dose is always superior and are willing to discuss individualized dosing with patients. Given potential improvements regarding quality of life and clinical care, dose modifications should be part of routine shared decision-making between patients and oncologists.

Embracing Project Optimus: Can we Leverage Evolutionary Theory to Optimize Dosing in Oncology?

Project Optimus is a US Food and Drug Administration (FDA) initiative to reform dose selection in oncology drug development. Here, we focus on tumor evolution, a broadly observed phenomenon that invariably leads to therapeutic failure and disease relapse, and its effect on the exposure-response (E-R) relationships of oncology drugs. We propose a greater emphasis on tumor evolution during clinical development to facilitate the selection of optimal doses for molecularly targeted therapies and immunotherapies in oncology.

Oncologists' Perspectives on Individualizing Dose Selection for Patients With Metastatic Cancer

PURPOSE

Treatment goals for patients with metastatic cancer include prolongation and maintenance of quality of life. Patients and oncologists have questioned the current paradigm of initial dose selection for systemic therapy; however, data on oncologists' dose selection strategies and beliefs are lacking.

METHODS

We conducted an electronic international survey of medical oncologists who treat patients with breast and/or gastrointestinal cancers. Survey questions addressed experiences with, and attitudes toward, dose reduction at initiation (DRI) of a new systemic therapy for patients with metastatic cancer.

RESULTS

Among 3,099 eligible oncologists, 367 responded (response rate 12%). Most (52%) reported using DRI at least 10% of the time to minimize toxicities. Gastrointestinal specialists were more likely to report DRI ≥ 10% of the time (72% v 50% of generalists and 51% of breast specialists, P < .005). Of those who dose reduced ≥ 10% of the time, 89% reported discussing potential tradeoffs between efficacy and toxicity with patients. Overall, 65% agreed it is acceptable to lower starting doses to reduce side effects even if it compromises efficacy; younger clinicians were more likely to agree (P < .005). There was strong support (89%) for future trials to determine optimal effective, rather than maximum tolerated, dose.

CONCLUSION

Oncology practice varies with regard to discussion and individualized selection of starting doses in the metastatic setting. This study demonstrates a need for consideration of shared decision making regarding initial dose selection and strong support among oncologists for clinical studies to define optimal dosing and best practices for individualizing care.

Determining drug dose in the era of targeted therapies: playing it (un)safe?

Targeted therapies against phosphatidylinositol 3-kinase (PI3K), Bruton’s tyrosine kinase (BTK), and B-cell lymphoma-2 (BCL-2) are approved for chronic lymphocytic leukemia (CLL). Since approval of the first-in-class drugs, next-generation agents have become available and are continuously under development. While these therapies act on well-characterized molecular targets, this knowledge is only to some extent taken into consideration when determining their dose in phase I trials. For example, BTK occupancy has been assessed in dose-finding studies of various BTK inhibitors, but the minimum doses that result in full BTK occupancy were not determined. Although targeted agents have a different dose–response relationship than cytotoxic agents, which are more effective near the maximum tolerated dose, the traditional 3 + 3 toxicity-driven trial design remains heavily used in the era of targeted therapies. If pharmacodynamic biomarkers were more stringently used to guide dose selection, the recommended phase II dose would likely be lower as compared to the toxicity-driven selection. Reduced drug doses may lower toxicity, which in some cases is severe for these agents, and are supported by retrospective studies demonstrating non-inferior outcomes for patients with clinically indicated dose reductions. Here, we review strategies that were used for dose selection in phase I studies of currently approved and select investigational targeted therapies in CLL, and discuss how our initial clinical experience with targeted therapies have pointed to dose reductions, intermittent dosing, and drug combinations as strategies to overcome treatment intolerance and resistance.

Novel omics technology driving translational research in precision oncology

In this review, we summarize the current challenges faced by cancer researchers and motivate the use of novel genomics solutions. We follow this up with a comprehensive overview of three recent genomics technologies: liquid biopsy, single-cell RNA sequencing and spatial transcriptomics. We discuss a few representative protocols/assays for each technology along with their strengths, weaknesses, optimal use-cases, and their current stage of clinical deployment by summarizing trial data. We focus on how these technologies help us develop a better understanding of cancer as a rapidly evolving heterogeneous genetic disease that modulates its immediate microenvironment leading to systemic macro-level changes in the patient body. We summarize the review with a flowchart that integrates these three technologies in the existing workflows of clinicians and researchers toward robust detection, accurate diagnosis, and precision oncology.

A prospective, multi-centre, Veterinary Radiation Therapy Oncology Group study reveals potential efficacy of toceranib phosphate (Palladia) as a primary or adjuvant agent in the treatment of canine nasal carcinoma

Radiation is the standard of care for dogs with nasal tumours. The addition of another therapy that could improve outcome without increasing toxicity is attractive. Medical therapy that could offer better outcome than maximally tolerated dose chemotherapy when radiation therapy (RT) is not possible or is declined is also attractive. This article reports the findings from a prospective, multi-centre, non-randomized, Veterinary Radiation Therapy Oncology Group clinical trial designed to evaluate whether toceranib phosphate (toceranib) has primary activity and if the addition of toceranib to RT could positively impact outcome. Owner's discretion determined enrolment in toceranib alone or toceranib + RT arm. Historical controls for radiation alone were selected from patients treated with identical RT and imaging protocols. Responses were evaluated with pre-treatment and week-16 CT scans. RT total dose of 42 Gy was completed in 10 fractions. Sixty-three dogs enrolled from 10 study sites. Overall response rates (CR + PR) were significantly improved in the toceranib + RT (79.4%) and RT alone (68.9%) arms over toceranib alone (22%) (p = .011). Clinical benefit rates (CR + PR + SD) were significantly improved in the toceranib + RT arm over the RT alone arm at 97.3% and 79.2% respectively (p = .036). Treatment with toceranib alone, toceranib + RT and RT alone resulted in median survival times of 298, 615 and 368 days respectively, but were not statistically significantly different (p = .0502). Adverse events associated with toceranib administration did not potentiate the RT side effect profile. Toceranib appears to have primary activity against nasal carcinoma.

Healthy volunteers in first-in-human oncology drug development for small molecules

This review provides tools to consider the inclusion of healthy volunteers (HVs) in first-in-human (FIH) oncology clinical trials with small molecules, including targeted and immunomodulatory agents, a strategy that was not envisioned with classic chemotherapy. To enable an FIH oncology trial in HVs compared to cancer patients (CPs), a robust nonclinical package must be generated, which includes toxicokinetic and pharmacokinetic studies, as well as more extensive safety pharmacology, toxicology and genotoxicity studies. This strategy could provide an early clinical characterization of the pharmacokinetic parameters and clinical safety profile in the absence of comorbidities and concomitant medication. It also avoids the ethical issue of administrating subtherapeutic doses to CPs, and could potentially help to accelerate the timelines of clinical drug development for patient care. That being said, stakeholders involved in these studies need to proceed with caution, fully understand the regulatory guidance and thoroughly evaluate the benefits and risks. This paper serves to address the regulatory guidance and other considerations needed when using healthy volunteers in early oncology trials.

New strategies for targeting kinase networks in cancer

Targeted strategies against specific driver molecules of cancer have brought about many advances in cancer treatment since the early success of the first small-molecule inhibitor Gleevec. Today, there are a multitude of targeted therapies approved by the Food and Drug Administration for the treatment of cancer. However, the initial efficacy of virtually every targeted treatment is often reversed by tumor resistance to the inhibitor through acquisition of new mutations in the target molecule, or reprogramming of the epigenome, transcriptome, or kinome of the tumor cells. At the core of this clinical problem lies the assumption that targeted treatments will only be efficacious if the inhibitors are used at their maximum tolerated doses. Such aggressive regimens create strong selective pressure on the evolutionary progression of the tumor, resulting in resistant cells. High-dose single agent treatments activate alternative mechanisms that bypass the inhibitor, while high-dose combinatorial treatments suffer from increased toxicity resulting in treatment cessation. Although there is an arsenal of targeted agents being tested clinically and preclinically, identifying the most effective combination treatment plan remains a challenge. In this review, we discuss novel targeted strategies with an emphasis on the recent cross-disciplinary studies demonstrating that it is possible to achieve antitumor efficacy without increasing toxicity by adopting low-dose multitarget approaches to treatment of cancer and metastasis.

Phase II Trial of Trametinib and Panitumumab in RAS/RAF Wild Type Metastatic Colorectal Cancer

INTRODUCTION

MEK inhibition may overcome resistance to EGFR inhibition in patients with RAS wildtype (wt) metastatic colorectal cancer (mCRC). We evaluated antitumor activity of trametinib (MEK1/2 inhibitor) with panitumumab (EGFR monoclonal antibody) in a phase II trial.

METHODS

Patients with KRAS, NRAS, and BRAF wt mCRC with prior 5-FU, irinotecan, oxaliplatin, +/- bevacizumab and no prior anti-EGFR therapy were treated with trametinib 1.5 mg oral daily and panitumumab 4.8 mg/kg IV every 2 weeks. Primary endpoint was clinical benefit rate (CB; CR, PR, or SD ≥24 weeks) by RECIST v1.1. A 2-stage minimax design was used. Serial plasma circulating free DNA (cfDNA) was collected and profiled using Oncomine Lung cfDNA assay.

RESULTS

Fourteen patients were enrolled from November 2015 to April 2019. CB rate was 38% (5/13) and median progression free survival (PFS) was 4.4 months (95% CI, 2.9-7.1). Confirmed overall response rate was 38% (5/13). Treatment-related AE (trAE) included acneiform rash (85%), diarrhea (62%), maculopapular rash (54%), mucositis (46%), and others. Dose modifications and interruptions of trametinib occurred in 69% and panitumumab in 54% of patients. The trial did not progress to stage II accrual due to tolerability and short duration of response. RAS or BRAF mutations cfDNA were detected in 3/13 patients (23%) before radiographic disease progression.

CONCLUSION

The addition of trametinib to panitumumab led to a high rate of tumor shrinkage in RAS/RAF wt metastatic colorectal cancer, with poor tolerability due to a high incidence of skin toxicity. Median PFS was similar to panitumumab alone in historical control data.

A two-stage Bayesian adaptive design for minimum effective dose (MinED)-based dosing-finding trials

Conventional phase I designs for finding a phase II recommended dose (P2RD) based on toxicity alone is problematic because the maximum tolerated dose (MTD) is not necessarily the optimal dose. Instead, recently attention has been given to find the minimum effective dose (MinED) - defined as the lowest effective dose. Traditional paradigms for the MinED studies are conducted as dose-ranging or dose-response trials which involve several doses and randomize patients among doses to find the MinED. An alternative approach for the MinED study is the so-called MinED-based dose-finding study, in which instead of conducting hypothesis testings and without power analysis, this kind of trial conduct dose escalation/de-escalation to target a pre-set MinED target. In this study, we propose a new Bayesian two-stage adaptive design schema based on framework of the interval-based phase I method. The proposed method is model-free without curve pre-specifications, which is suitable for various dose-efficacy relationships. The proposed method shows desirable theoretical finite property of semi-coherence and large sample property of consistency. A random scenario generative algorithm for the MinED has also been proposed for extensive simulation studies, which demonstrated desirable performances of the proposed method. An R package "MinEDfind" and a Shiny app have been developed for implementing the method.

Systemic Treatment for Older Patients with Unresectable Hepatocellular Carcinoma

The incidence rate of hepatocellular carcinoma is growing and age at diagnosis is increasing; however, despite the unprecedented wealth of therapeutic options for advanced HCC, its optimal management in some categories, such as older adults, is yet to be defined. Even though age is not an exclusion criterion per se, most of the landmark trials enrolled a limited number of senior patients, raising some concerns on the potential benefit of active treatments in this group. The identification of more vulnerable patients remains a crucial issue in clinical practice. In fact, the suitability assessment for systemic therapy through performance status metrics might underestimate or conversely overestimate the fitness of older patients, failing to detect other relevant impairments. Thus, the assessment of frailty through geriatric screening scales is largely necessary. In addition, most of the available data relate to the use of sorafenib, while very little is known about the most recent therapeutic agents. Age subgroup analyses provided by many of the pivotal trials did not find significant efficacy or safety differences across ages; however, the most widely used cut-off age of 65 years may not be very informative for the current older population. Regarding immunotherapy, the clinical benefit reported with immune checkpoint inhibitors reassures their safe use in senior patients and supports further investigations to assess their efficacy in this population.

Moving Beyond 3+3: The Future of Clinical Trial Design

Misgivings have been raised about the operating characteristics of the canonical 3+3 dose-escalation phase I clinical trial design. Yet, the traditional 3+3 design is still the most commonly used. Although it has been implied that adhering to this design is due to a stubborn reluctance to adopt change despite other designs performing better in hypothetical computer-generated simulation models, the continued adherence to 3+3 dose-escalation phase I strategies is more likely because these designs perform the best in the real world, pinpointing the correct dose and important side effects with an acceptable degree of precision. Beyond statistical simulations, there are little data to refute the supposed shortcomings ascribed to the 3+3 method. Even so, to address the unique nuances of gene- and immune-targeted compounds, a variety of inventive phase 1 trial designs have been suggested. Strategies for developing these therapies have launched first-in-human studies devised to acquire a breadth of patient data that far exceed the size of a typical phase I design and blur the distinction between dose selection and efficacy evaluation. Recent phase I trials of promising cancer therapies assessed objective tumor response and durability at various doses and schedules as well as incorporated multiple expansion cohorts spanning a variety of histology or biomarker-defined tumor subtypes, sometimes resulting in U.S. Food and Drug Administration approval after phase I. This article reviews recent innovations in phase I design from the perspective of multiple stakeholders and provides recommendations for future trials.

The Use of Patient-Reported Outcome Measures in Phase I Oncology Clinical Trials

OBJECTIVE

To investigate patient-reported outcome (PRO) usage in phase I oncology clinical trials, including types of PRO measures and changes over time.

METHODS

We analyzed ClinicalTrials.gov records of phase I oncology clinical trials completed by December 2019.

RESULTS

Of all eligible trials, 2.3% (129/5,515) reported ≥1 PRO, totaling 181 instances of PRO usage. PRO usage increased over time, from 0.6% (trials initiated before 2000) to 3.4% (trials starting between 2015 and 2019). The most common PRO measures were unspecified (29%), tumor-specific (24%), and generic cancer (19%).

CONCLUSION

Although uncommon in phase I oncology clinical trials, PRO usage is increasing over time. PRO measures were often unspecified on ClinicalTrials.gov, suggesting that more precise reporting and standardization are needed.

Systemic treatment of HCC in special populations

Recent years have seen significant progress in the systemic treatment of hepatocellular carcinoma (HCC), including the advent of immunotherapy. While several large phase III trials have provided the evidence for a multi-line treatment paradigm, they have focused on a highly selected group of patients by excluding potentially confounding comorbidities. As a result, high quality evidence for the systemic treatment of HCC in patients with various comorbidities is missing. This review summarises current knowledge on the use of approved medicines in patients with HIV, autoimmune disease, cardiovascular disease, diabetes, fibrolamellar HCC, mixed HCC-cholangiocarcinoma, decompensated cirrhosis (Child-Pugh B and C), a significant bleeding history, vascular invasion or portal vein thrombosis, as well as the elderly, those on haemodialysis, and those after solid organ transplantation. The article highlights relevant knowledge gaps and current clinical challenges. To improve the safety and efficacy of HCC treatment in these subgroups, future trials should be designed to specifically include patients with comorbidities.

The Challenge of Combining Chemo- and Radiotherapy with Checkpoint Kinase Inhibitors

Preclinical models of cancer have demonstrated enhanced efficacy of cell-cycle checkpoint kinase inhibitors when used in combination with genotoxic agents. This combination therapy is predicted to be exquisitely toxic to cells with a deficient G1-S checkpoint or cells with a genetic predisposition leading to intrinsic DNA replication stress, as these cancer cells become fully dependent on the intra-S and G2-M checkpoints for DNA repair and cellular survival. Therefore, abolishing remaining cell-cycle checkpoints after damage leads to increased cell death in a tumor cell-specific fashion. However, the preclinical success of these drug combinations is not consistently replicated in clinical trials. Here, we provide a perspective on the translation of preclinical studies into rationally designed clinical studies. We will discuss successes and failures of current treatment combinations and drug regimens and provide a detailed overview of all clinical trials using ATR, CHK1, or WEE1 inhibitors in combination with genotoxic agents. This highlights the need for revised patient stratification and the use of appropriate pharmacodynamic biomarkers to improve the success rate of clinical trials.

Optimized low-dose combinatorial drug treatment boosts selectivity and efficacy of colorectal carcinoma treatment

The current standard of care for colorectal cancer (CRC) is a combination of chemotherapeutics, often supplemented with targeted biological drugs. An urgent need exists for improved drug efficacy and minimized side effects, especially at late‐stage disease. We employed the phenotypically driven therapeutically guided multidrug optimization (TGMO) technology to identify optimized drug combinations (ODCs) in CRC. We identified low‐dose synergistic and selective ODCs for a panel of six human CRC cell lines also active in heterotypic 3D co‐culture models. Transcriptome sequencing and phosphoproteome analyses showed that the mechanisms of action of these ODCs converged toward MAP kinase signaling and cell cycle inhibition. Two cell‐specific ODCs were translated to in vivo mouse models. The ODCs reduced tumor growth by ~80%, outperforming standard chemotherapy (FOLFOX). No toxicity was observed for the ODCs, while significant side effects were induced in the group treated with FOLFOX therapy. Identified ODCs demonstrated significantly enhanced bioavailability of the individual components. Finally, ODCs were also active in primary cells from CRC patient tumor tissues. Taken together, we show that the TGMO technology efficiently identifies selective and potent low‐dose drug combinations, optimized regardless of tumor mutation status, outperforming conventional chemotherapy.

Machine learning model to predict oncologic outcomes for drugs in randomized clinical trials

Predicting oncologic outcome is challenging due to the diversity of cancer histologies and the complex network of underlying biological factors. In this study, we determine whether machine learning (ML) can extract meaningful associations between oncologic outcome and clinical trial, drug-related biomarker and molecular profile information. We analyzed therapeutic clinical trials corresponding to 1102 oncologic outcomes from 104 758 cancer patients with advanced colorectal adenocarcinoma, pancreatic adenocarcinoma, melanoma and nonsmall-cell lung cancer. For each intervention arm, a dataset with the following attributes was curated: line of treatment, the number of cytotoxic chemotherapies, small-molecule inhibitors, or monoclonal antibody agents, drug class, molecular alteration status of the clinical arm's population, cancer type, probability of drug sensitivity (PDS) (integrating the status of genomic, transcriptomic and proteomic biomarkers in the population of interest) and outcome. A total of 467 progression-free survival (PFS) and 369 overall survival (OS) data points were used as training sets to build our ML (random forest) model. Cross-validation sets were used for PFS and OS, obtaining correlation coefficients (r) of 0.82 and 0.70, respectively (outcome vs model's parameters). A total of 156 PFS and 110 OS data points were used as test sets. The Spearman correlation (r_s ) between predicted and actual outcomes was statistically significant (PFS: r_s = 0.879, OS: r_s = 0.878, P < .0001). The better outcome arm was predicted in 81% (PFS: N = 59/73, z = 5.24, P < .0001) and 71% (OS: N = 37/52, z = 2.91, P = .004) of randomized trials. The success of our algorithm to predict clinical outcome may be exploitable as a model to optimize clinical trial design with pharmaceutical agents.

Phase I trials as valid therapeutic options for patients with cancer

For many years, oncology phase I trials have been referred to as 'toxicity trials' and have been believed to have low clinical utility other than that of establishing the adverse event profile of novel therapeutic agents. The traditional distinction of clinical trials into three phases has been challenged in the past few years by the introduction of targeted therapies and immunotherapies into the routine management of patients with cancer. This transformation has especially affected early phase trials, leading to the current situation in which response rates are increasingly reported from phase I trials. In this Perspectives, we highlight key elements of phase I trials and discuss how each one of them contributes to a new paradigm whereby preliminary measurements of the clinical benefit from a novel treatment can be obtained in current phase I trials, which can therefore be considered to have a therapeutic intent.

Dacomitinib in non-small-cell lung cancer: a comprehensive review for clinical application

Dacomitinib is a second-generation EGFR tyrosine kinase inhibitor (TKI) that irreversibly binds to and inhibits EGFR/Her1, Her2 and Her4 subtypes with an efficacy comparable to other TKIs. In the ARCHER 1050 trial, progression-free survival was improved by dacomitinib compared with gefitinib, supporting dacomitinib as a first-line treatment option for advanced non-small-cell lung cancer with sensitive EGFR mutation. Regarding to the higher adverse events rate, dose reductions did not reduce the efficacy of dacomitinib and could effectively decreased the incidence and severity of adverse events. Considering the evolving landscape of EGFR-mutant non-small-cell lung cancer, future head to head comparison between dacomitinib and osimertinib could provide key information to determine the optimal TKI treatment schedule.

Generalization of the time-to-event continual reassessment method to bivariate outcomes

This article considers the problem of designing Phase I-II clinical trials with delayed toxicity and efficacy outcomes. The proposed design is motivated by a Phase I-II study evaluating all-trans retinoic acid (ATRA) in combination with a fixed dose of daratumumab in the treatment of relapsed or refractory multiple myeloma. The primary objective of the study is to identify a dose that maximizes efficacy and has an acceptable level of toxicity. The toxicity endpoint is observed in one cycle of therapy (i.e., 4 weeks) while the efficacy endpoint is assessed after 8 weeks of treatment. The difference in endpoint observation windows causes logistical challenges in conducting the trial, since it is not practical to wait until both outcomes for each patient have been fully observed before sequentially assigning the dose of a newly eligible patient. In order to avoid delays in treatment for newly enrolled patients and to accelerate trial progress, we generalize the time-to-event continual reassessment method (TITE-CRM) to bivariate outcomes. Simulation studies are conducted to evaluate the proposed method, and we found that the proposed design is able to accurately select doses that maximize efficacy and have acceptable toxicity, while using all available information in allocating patients at the time of dose assignment. We compare the proposed methodology to two existing methods in the area.

Copenhagen Prospective Personalized Oncology (CoPPO)-Clinical Utility of Using Molecular Profiling to Select Patients to Phase I Trials

PURPOSE

We evaluated the clinical benefit of tumor molecular profiling to select treatment in the phase I setting.

EXPERIMENTAL DESIGN

Patients with advanced solid cancers and exhausted treatment options referred to a phase I unit were included in a prospective, single-center, single-arm open-label study (NCT02290522). Tumor biopsies were obtained for comprehensive genomic analysis including whole-exome sequencing and RNA sequencing. When possible, patients were treated with regimen matched to the genomic profile. Primary endpoint was progression-free survival (PFS).

RESULTS

From May 2013 to January 2017, a total of 591 patients were enrolled, with 500 patients undergoing biopsy. Genomic profiles were obtained in 460 patients and a potential actionable target was identified in 352 (70%) of 500 biopsied patients. A total of 101 patients (20%) received matched treatment based on either gene mutations or RNA expression levels of targets available in early clinical trials or off-label treatment. Objective response according to RECIST1.1 was observed in 15 of 101 patients (0% complete response, 15% partial response), with a median PFS of 12 weeks (95% confidence interval, 9.9-14.4).

CONCLUSIONS

Our study supports the feasibility of genomic profiling to select patients in the phase I setting and suggests that genomic matching can be beneficial for a minor subset of patients with no other treatment options. Randomized studies may validate this assumption.See related commentary by Ratain, p. 1136.

Older adults in phase I clinical trials: a comparative analysis of participation and clinical benefit rate among older adults versus middle age and AYA patients on phase I clinical trials with VEGF/VEGFR inhibitors

Background

Older adults aged 65 years and above remain underrepresented in cancer clinical trials. We hypothesized that older participation in early phase trials with VEGF/VEGFR (VEGF/R) inhibitors was lower than cancer prevalence in this group and lower than other age groups (middle age, adolescent/young adults [AYA]).

Results

Of 1489 patients, 278 were older adults (18%, median age 68.9y), 220 AYA (15%, median age 32.6 y), 991 middle age (67%, median age 53.8 y). Common malignancies included gastrointestinal (n = 438, 29%), gynecologic (n = 234, 16%), and thoracic/head/neck (n = 216, 15%). Median time to treatment failure did not vary significantly between the 3 age-based cohorts (3m in older adults, 3.5 m middle age, 3.3 m AYA). OR of achieving clinical benefit in older adults vs middle age (OR 1.10, p 0.19 [two-tailed], p 0.09 [one-tailed]) and AYA vs middle age (OR 0.85, p 0.31 [proportions z-test, two tailed], p 0.15 [one-tailed]) showed no significant differences.

Conclusions

Older adults accounted for <20% of participants on phase I clinical trials with VEGF/R inhibitors but those who participated were just as likely to achieve a clinical benefit as AYA and middle age patients. These findings merit further exploration into patient selection for early phase trials.

Methods

We identified and separated patients treated on VEGF/R-inhibitor-based phase I trials from 12/1/2004–07/31/2013 into 3 age-based cohorts, AYA (15–39y), middle age (40–64 y), older adults (65 y+). We analyzed clinical/treatment characteristics and response outcomes, calculating the odds ratios (OR) of clinical benefit (defined as SD ≥ 6months, PR, CR) for older adults and AYAs versus middle age participants.

Mechanistic Distinctions between CHK1 and WEE1 Inhibition Guide the Scheduling of Triple Therapy with Gemcitabine

Combination of cytotoxic therapy with emerging DNA damage response inhibitors (DDRi) has been limited by tolerability issues. However, the goal of most combination trials has been to administer DDRi with standard-of-care doses of chemotherapy. We hypothesized that mechanism-guided treatment scheduling could reduce the incidence of dose-limiting toxicities and enable tolerable multitherapeutic regimens. Integrative analyses of mathematical modeling and single-cell assays distinguished the synergy kinetics of WEE1 inhibitor (WEE1i) from CHEK1 inhibitor (CHK1i) by potency, spatiotemporal perturbation, and mitotic effects when combined with gemcitabine. These divergent properties collectively supported a triple-agent strategy, whereby a pulse of gemcitabine and CHK1i followed by WEE1i durably suppressed tumor cell growth. In xenografts, CHK1i exaggerated replication stress without mitotic CDK hyperactivation, enriching a geminin-positive subpopulation and intratumoral gemcitabine metabolite. Without overt toxicity, addition of WEE1i to low-dose gemcitabine and CHK1i was most effective in tumor control compared with single and double agents. Overall, our work provides quantitative insights into the mechanisms of DDRi chemosensitization, leading to the rational development of a tolerable multitherapeutic regimen.Significance: Multiple lines of mechanistic insight regarding DNA damage response inhibitors rationally guide the preclinical development of a tolerable multitherapeutic regimen.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/78/11/3054/F1.large.jpg Cancer Res; 78(11); 3054-66. ©2018 AACR.

Determination of a radotinib dosage regimen based on dose-response relationships for the treatment of newly diagnosed patients with chronic myeloid leukemia

Radotinib is a second-generation BCR-ABL1 tyrosine kinase inhibitor approved for the treatment of chronic myeloid leukemia in chronic phase (CP-CML). Here, using the data from a Phase 3 study conducted in patients with newly diagnosed CP-CML, the dose-efficacy as well as dose-safety relationship analyses were performed to determine a safe and effective initial dosage regimen of radotinib. A significant positive association was detected between the starting dose of radotinib adjusted for body weight (Dose/BW) and the probability of dose-limiting toxicity (≥grade 3 hematologic and nonhematologic toxicity) (P = 0.003). In contrast, a significant inverse association was discovered between Dose/BW and the probability of major molecular response (BCR-ABL1/ABL1 ≤ 0.1%) when controlled for sex (P = 0.033). Moreover, frequent dose interruptions and reductions secondary to radotinib toxicities occurred in the Phase 3 study, resulting in nearly half (44%) of patients receiving a reduced dose at a 12-month follow-up. In conclusion, the results of this study demonstrate the need for initial radotinib dose attenuation to improve the long-term efficacy and safety of radotinib. Hence, the authors suggest a new upfront radotinib dose of 400 mg once daily be tested in patients with newly diagnosed CP-CML.

A first-in-human phase I study to determine the maximum tolerated dose of the oral Src/ABL inhibitor AZD0424

BACKGROUND

Src is involved in cancer invasion and metastasis. AZD0424, an oral inhibitor of Src and ABL1, has shown evidence of anti-tumour activity in pre-clinical studies.

METHODS

A phase Ia, dose escalation study was performed to assess the safety of continuous oral dosing with AZD0424 in advanced solid tumours. Secondary objectives included investigation of AZD0424 pharmacokinetics, effect on Src activity using markers of bone turnover, and anti-tumour activity.

RESULTS

41 patients were treated; 34 received AZD0424 once-daily at doses ranging from 5 mg to 150 mg, and 7 received 40 mg bi-daily 41.5% of patients experienced at least one AZD0424-related adverse event that was Grade 3-5 in severity, with patients treated at doses above 60 mg per day experiencing multiple treatment-related toxicities. The most commonly observed AZD0424-related adverse events were nausea, fatigue, anorexia and alopecia. Cmax and AUC increased linearly with dose and the mean±standard deviation t1/2 was 8.4±2.8 h. Clear evidence of Src target inhibition was seen at doses ⩾20 mg per day. No responses were observed and 7 patients (17.1%) achieved stable disease lasting 6 weeks or more.

CONCLUSIONS

AZD0424 displayed no evidence of efficacy as monotherapy despite a clear pharmacodynamic effect. Further evaluation of AZD0424 monotherapy in patients with solid tumours is not recommended.

Adaptive designs for identifying optimal biological dose for molecularly targeted agents

Background Traditionally, the purpose of a dose-finding design in cancer is to find the maximum tolerated dose based solely on toxicity. However, for molecularly targeted agents, little toxicity may arise within the therapeutic dose range and the dose-response curves may not be monotonic. This challenges the principle that more is better, which is widely accepted for conventional chemotherapy. Methods We propose three adaptive dose-finding designs for trials evaluating molecularly targeted agents, for which the dose-response curves are unimodal or plateaued. The goal of these designs is to find the optimal biological dose, which is defined as the lowest dose with the highest rate of efficacy while safe. The first proposed design is parametric and assumes a logistic dose-efficacy curve for dose finding, the second design is nonparametric and uses the isotonic regression to identify the optimal biological dose, and the third design has the spirit of a 'semiparametric' approach by assuming a logistic model only locally around the current dose. Results We conducted extensive simulation studies to investigate the operating characteristics of the proposed designs. Simulation studies show that the nonparametric and semiparametric designs have good operating characteristics for finding the optimal biological dose. Limitations The proposed designs assume a binary endpoint. Extension of the proposed designs to ordinal and time-to-event endpoints is worth further investigation. Conclusion Among the three proposed designs, the nonparametric and semiparametric designs yield consistently good operating characteristics and thus are recommended for practical use. The software to implement these two designs is available for free download at http://odin.mdacc.tmc.edu/~yyuan/ .

Dosing de novo combinations of two targeted drugs: Towards a customized precision medicine approach to advanced cancers

Metastatic cancers harbor complex genomic alterations. Thus, monotherapies are often suboptimal. Individualized combinations are needed in order to attenuate resistance. To help inform selection of safe starting doses for novel, two-agent, targeted drug combinations, we identified clinical trials in adult oncology patients who received targeted drug doublets (PubMed, January 1, 2010 through December 31, 2013). The dose percentage was calculated for each drug: (safe dose in combination divided by single agent full dose) X 100. Additive dose percentage represented the sum of the dose percentage for each drug. A total of 144 studies (N = 8568 patients; 95 combinations) were analyzed. In 51% of trials, each of the two drugs could be administered at 100% of their full dose. The lowest safe additive dose percentage was 60% if targets and/or class of drugs overlapped, or in the presence of mTor inhibitors, which sometimes compromised the combination dose. If neither class nor target overlapped and if mTor inhibitors were absent, the lowest safe additive dose percentage was 143%. The current observations contribute to the knowledge base that informs safe starting doses for new combinations of targeted drugs in the context of clinical trials or practice, hence facilitating customized combination therapies.

Evolution of early phase clinical trials in oncology

The therapeutic armamentarium for the treatment of cancer has rapidly evolved with the advent of molecularly targeted and immuno-oncology agents. Dramatic and prolonged responses observed in patients with advanced cancers have created excitement and promise for expedited development of effective new treatments. However, this has also necessitated a rethinking of our early phase clinical trial designs and the process of optimally developing a novel agent. In this review, we discuss the current state and future directions of phase I clinical trials in oncology. Firstly, we cover the statistical methodologies behind rules and model-based dose escalation designs, and what the future holds for optimal dose selection beyond targeting the maximum tolerated dose. Next, we discuss the recent adoption of seamless expansion strategies to expedite drug development timelines, highlighted by the pembrolizumab KEYNOTE-001 trial, and potential pitfalls with this approach. Finally, we delve into the concepts behind genomic matching trials, including early success stories and the challenges that lie ahead.

Dosing immunotherapy combinations: Analysis of 3,526 patients for toxicity and response patterns

Immunotherapy combinations are used to improve outcomes in metastatic cancer, but evidence-based knowledge of appropriate starting doses for novel combinations is lacking. Phase I-III adult combination clinical trials (≥ 1 drug was immunotherapy; anti-PD-1, PD-L1, or CTLA-4) were reviewed (PubMed Jan 1, 2010 to Sep 1, 2016; ASCO 2014-2016, ASH/ESMO 2014-2015 abstracts). The safe dose for each drug used in each combination was divided by the single-agent recommended dose to calculate dose percentage. Additive dose percentage was the sum of each dose percentage. Overall, 84 studies (N = 3,526 patients, 59 combinations) were analyzed. In 50% of studies, all drugs could be administered at full dose; 63%, in the presence of anti-PD-1/PD-L1 and 36% with anti-CTLA-4. The lowest safe starting dose for a doublet combination including a second immunotherapy was 50% of each drug; 60%, for a targeted agent. Most doublet/triplets combining anti-PD-1/PD-L1 with cytotoxics were tolerable at full doses. Response rates (median [interquartile range]) were higher for 3-drug than 2-drug combinations (53% [33-63%] (N = 23 studies) vs. 23% [14-39%]) (N = 60 studies) (p < 0.0001) with similar rates seen for targeted, cytotoxic, biologic, or additional immunotherapy combinations (p = 0.35). In conclusion, anti-PD-1/PD-L1 checkpoint inhibitors can be safely given with a variety of other immunotherapy and targeted agents, albeit at about half dose. Doublet and triplet combinations with cytotoxics could mostly be given at full doses. Anti-CTLA-4 agents compromised dosing more than anti-PD-1/PD-L1 agents. Response rates were significantly higher for 3- versus 2-drug combinations.

Challenges and Innovations in Phase I Dose-Finding Designs for Molecularly Targeted Agents and Cancer Immunotherapies

Phase I oncology trials are designed to identify a safe dose with an acceptable toxicity profile. In traditional phase I dose-finding design, the dose is typically determined based on the probability of severe toxicity observed during the first treatment cycle. The recent development of molecularly targeted agents and cancer immunotherapies call for new innovations in phase I designs, because of prolonged treatment cycles often involved. Various phase I designs using toxicity and efficacy endpoints from multiple treatment cycles have been developed for these new treatment agents. Here, we will review the novel endpoints and designs for the phase I oncology clinical trials.

Dosing Three-Drug Combinations That Include Targeted Anti-Cancer Agents: Analysis of 37,763 Patients

BACKGROUND

Combining targeted and cytotoxic agents has the potential to improve efficacy and attenuate resistance for metastatic cancer. Information regarding safe starting doses for clinical trials of novel three-drug combinations is lacking.

MATERIALS AND METHODS

Published phase I-III adult oncology clinical trials of three-drug combinations involving a targeted agent were identified by PubMed search (January 1, 2010 to December 31, 2013). A dose percentage was calculated to compare the dose used in combination to the single agent recommended dose: (U.S. Food and Drug Administration-approved/recommended phase II dose/maximum tolerated dose). The additive dose percentage was the sum of the dose percentages for each drug in the combination.

RESULTS

A total of 37,763 subjects and 243 drug combinations were included. Only 28% of studies could give each of the three agents at 100%. For combinations involving two targeted agents and a cytotoxic agent, the lowest starting additive dose percentage was 133%, which increased to 250% if two antibodies were included. For combinations of one targeted agent and two cytotoxic agents, the lowest additive safe dose percentage was 137%. When both cytotoxic agents were held at 100%, as occurred in 56% of studies (which generally used cytotoxic doublets with known combination safety dosing), the lowest safe dose percentage was 225% (providing that a histone deacetylase inhibitor was not the targeted agent).

CONCLUSION

These findings serve as a safe starting point for dosing novel three-drug combinations involving a targeted agent in clinical trials and practice. The Oncologist 2017;22:576-584 IMPLICATIONS FOR PRACTICE: Targeted and cytotoxic drug combinations can improve efficacy and overcome resistance. More knowledge of safe starting doses would facilitate use of combinations in clinical trials and practice. Analysis of 37,763 subjects (243 combinations) showed three drugs could be safely administered, but less than 30% of combinations could include all three drugs at full dose. Dose reductions to 45% of the dose of each single agent may be required. Combinations involving two antibodies required fewer dose reductions, and the use of established cytotoxic doublets made initial dose assignment easier.

Clinical development of new drug-radiotherapy combinations

In countries with the best cancer outcomes, approximately 60% of patients receive radiotherapy as part of their treatment, which is one of the most cost-effective cancer treatments. Notably, around 40% of cancer cures include the use of radiotherapy, either as a single modality or combined with other treatments. Radiotherapy can provide enormous benefit to patients with cancer. In the past decade, significant technical advances, such as image-guided radiotherapy, intensity-modulated radiotherapy, stereotactic radiotherapy, and proton therapy enable higher doses of radiotherapy to be delivered to the tumour with significantly lower doses to normal surrounding tissues. However, apart from the combination of traditional cytotoxic chemotherapy with radiotherapy, little progress has been made in identifying and defining optimal targeted therapy and radiotherapy combinations to improve the efficacy of cancer treatment. The National Cancer Research Institute Clinical and Translational Radiotherapy Research Working Group (CTRad) formed a Joint Working Group with representatives from academia, industry, patient groups and regulatory bodies to address this lack of progress and to publish recommendations for future clinical research. Herein, we highlight the Working Group's consensus recommendations to increase the number of novel drugs being successfully registered in combination with radiotherapy to improve clinical outcomes for patients with cancer.

Trends in the characteristics, dose-limiting toxicities and efficacy of phase I oncology trials: The Cancer Research UK experience

INTRODUCTION

Phase I oncology trials have evolved over the years, and these changes could have implications for future studies and patients.

METHODS

Adult trials sponsored by Cancer Research UK Centre for Drug Development between 1995 and 2013 were analysed. Forty-nine trials were divided into two groups based on the starting date for recruitment: 1995-2003 (24 trials, n = 603) and 2004-2013 (25 trials, n = 750) for comparative purposes.

RESULTS

From 1995-2003 to 2004-2013, there was a shift towards studying non-cytotoxic agents that are administered orally. In later trials, patients tended to have better performance status, were older, had greater disease burden, and were more likely to have received prior treatment. In 2004-2013, wider variety of dose escalation designs were used, and studies were more likely to be multicentre, target/disease specific, conducted in first-/any-line setting and to require tumour biopsy. The overall incidence of dose-limiting toxicities (DLTs) was unchanged (10.9%; risk of death 0.4%), but DLTs such as neuropathy, stomatitis and thrombocytopaenia were less frequent in the more recent trials, while elevated liver enzymes were more frequent. Non-classical DLTs emerged in the later trials, including hypertension, hypophosphataemia, cardiac and ophthalmic toxicities. Disease control rate (DCR) increased from 27.9% (1995-2003) to 36.0% (2004-2013; P = 0.0033) due to higher rates of disease stabilisation.

CONCLUSION

Changes in trial designs, therapeutic agents, patient characteristics and DLTs were observed. Although the nature of DLTs changed, the incidence was similar in the two time periods and DCR improved, suggesting that the benefit-risk balance for patients participating in early-phase trials remains acceptable.

Dosing targeted and cytotoxic two-drug combinations: Lessons learned from analysis of 24,326 patients reported 2010 through 2013

Combining agents has the potential to attenuate resistance in metastatic cancer. However, knowledge of appropriate starting doses for novel drug combinations in clinical trials and practice is lacking. Analysis of 372 published studies was used to ascertain safe starting doses for doublets involving a cytotoxic and targeted agent. Phase I–III adult oncology clinical trial publications (January 1, 2010 to December 31, 2013) were identified (PubMed). The dose of drug used in each combination was compared to the single agent recommended dose [FDA‐approved/recommended phase 2 dose (RP2D)/maximum tolerated dose (MTD)]. Dose percentages were calculated as: (safe dose of drug in combination/dose of drug as single agent at FDA/RP2D/MTD) × 100. Additive dose percentages were the sum of the dose percentage for each drug. A total of 24,326 patients (248 drug combinations) were analyzed. In 38% of studies, both drugs could be administered at 100% of their FDA‐approved/RP2D/MTD dose. The lowest safe additive dose percentage was 41% with poly‐ADP ribose polymerase (PARP) or histone deacetylase inhibitors as the targeted agents; 82%, in the absence of these agents; and 97%, with an antibody in the combination. If one drug was administered at 100% of the single agent dose, the lowest safe dose percentage for the second drug was 17% (cytotoxic at 100%) or 36% (targeted at 100%) of the FDA‐approved/RP2D/MTD dose. The current findings can help inform safe starting doses for novel two‐drug combinations (cytotoxic and targeted agents) in the context of clinical trials and practice.

What's new?

Cytotoxic and targeted cancer drugs act through distinct mechanisms, and when used in combination they can potentially augment therapeutic effectiveness while minimally impacting toxicity. However, whereas algorithms for safe starting doses for new single‐agent therapies are well established, there are few guidelines for combination therapies. Here, analyses of data from published Phase I–III clinical trials shows that about 38% of patients tolerated combinations in which both drugs were administered at full starting doses. In the majority of patients, significant dose reductions were required to guard against toxicity. Intrapatient dose escalation is possible, however, potentially allowing for increased efficacy.