Pediatric Phase I Trials in Oncology: An Analysis of Study Conduct Efficiency

Physician and nurse beliefs of phase 1 trials in pediatric oncology

BACKGROUND

In order to improve the survival of children with cancer, novel therapies must be identified. Promising agents are tested in phase 1 trials in order to identify appropriate dosing and describe toxicity in children. The identification and referral of candidate patients for phase 1 trials rely heavily on medical providers who must balance their own perceptions of phase 1 trials with the desires and willingness of the patient and his/her family.

OBJECTIVE

The goal of the present study was to evaluate and compare physician and nurse perceptions regarding the beliefs, expectations, and perceived benefits of phase 1 clinical trials.

METHODS

A survey consisting of 21 questions was sent to 419 physicians and nurses practicing pediatric oncology at 30 different institutions. With the exception of 10 demographic questions, items were either rank ordered or rated on 5-point Likert scales.

RESULTS

Ninety-four physicians and 122 nurses completed the online survey. Physicians and nurses differed in their knowledge of the goals and medical effects of phase 1 clinical trials.

CONCLUSIONS

Physicians and nurses hold positive beliefs regarding phase 1 clinical trials and support their role in the treatment of children with cancer. Education is necessary to increase nurses' knowledge of the goals and outcomes.

IMPLICATIONS FOR PRACTICE

These findings suggest that continued education of nurses as well as physicians about the goals, execution, and monitoring of phase 1 therapy would be worthwhile.

Phase I and Phase II Objective Response Rates are Correlated in Pediatric Cancer Trials: An Argument for Better Clinical Trial Efficiency

Although many phase I trials report tumor response, formal analysis of efficacy is deferred to phase II. We reviewed paired phase I and II pediatric oncology trials to ascertain the relationship between phase I and II objective response rate (OR%). Single-agent phase I trials were paired with corresponding phase II trials (comparable study drug, dosing schedule, and population). Phase I trials without efficacy data or a matching phase II trial were excluded. OR% was tabulated for all trials, and phase II authors' subjective conclusions regarding efficacy were documented; 35 pairs of trials were analyzed. The correlation between phase I and II OR% was 0.93. Between phase II studies with a "positive" conclusion versus a "negative" one, there was a statistically significant difference in mean phase I OR% (32.0% vs. 4.5%, P<0.001). Thirteen phase II studies were undertaken despite phase I OR% of 0%; only 1 had a "positive" conclusion, and none exceeded OR% of 15%. OR% are highly correlated between phase I and II pediatric oncology trials. Although not a formal measure of drug efficacy, phase I OR% may provide an estimate of phase II response, inform phase II study design, and should be given greater consideration.

Innovations for phase I dose-finding designs in pediatric oncology clinical trials

Phase I oncology clinical trials are designed to identify the optimal dose that will be recommended for phase II trials. In pediatric oncology, the conduct of those trials raises specific challenges, as the disease is rare with limited therapeutic options. In addition, the tolerance profile is known from adult trials. This paper provides a review of the major recent developments in the design of these trials, inspired by the need to cope with the specific challenges of dose finding in cancer pediatric oncology. We reviewed simulation studies comparing designs dedicated to address these challenges. We also reviewed the design used in published dose-finding trials in pediatric oncology over the period 2009-2014. Three main fields of innovation were identified. First, designs that were developed in order to relax the rules for more flexible inclusions. Second, methods to incorporate data emerging from adult studies. Third, designs accounting for toxicity evaluation at repeated cycles in pediatric oncology. In addition to this overview, we propose some further directions for designing pediatric dose-finding trials.

Phase I study of 5-fluorouracil in children and young adults with recurrent ependymoma

BACKGROUND

We report a phase I study to examine the pharmacokinetics, safety, and recommended dosage of weekly intravenous bolus 5-fluorouracil (5-FU) in children and young adults with recurrent ependymoma.

METHODS

Patients 22 years of age or less with recurrent ependymoma were treated with bolus dosage 5-FU weekly for 4 weeks followed by a 2-week rest period, defining one cycle. Patients could continue on therapy for 16 cycles. The starting 5-FU dosage was 500 mg/m(2). Dose-limiting toxicity was determined after one cycle. Patients were initially enrolled according to a rolling-6 design; subsequent dose re-escalation phase was based on a 3 + 3 design.

RESULTS

We treated patients at 400 (n = 6), 500 (n = 15), and 650 (n = 5) mg/m(2), with de-escalation due to toxicity. Twenty-three of twenty-six patients enrolled were evaluable. Five patients experienced grade 4 neutropenia (n = 2: 650 mg/m(2); n = 3: 500 mg/m(2)). One patient experienced grade 3 diarrhea. At 500 mg/m(2), the median 5-FU maximal concentration, AUC0-∞, and alpha half-life were 825 µM, 205 µM × h, and 9.9 min, respectively. Interim analysis revealed an association between hematologic toxicity and prior number of chemotherapeutic regimens (P = .03). The study was amended to re-escalate the dosage in a less heavily pretreated cohort of patients.

CONCLUSIONS

These phase I clinical data provide initial pharmacokinetic parameters to describe i.v. bolus 5-FU disposition in children with recurrent ependymoma. Tumor exposures effective in preclinical testing can be achieved with tolerable bolus dosages in patients. Bolus 5-FU is well tolerated and possesses antitumor activity.

Does phase 1 trial enrollment preclude quality end-of-life care? Phase 1 trial enrollment and end-of-life care characteristics in children with cancer

BACKGROUND

End-of-life care (EOLC) discussions and treatment-related decisions, including phase 1 trial enrollment, in patients with incurable disease are complex and can influence the quality of EOLC received. The current study was conducted in pediatric oncology patients to determine whether end-of-life characteristics differed between those who were and were not enrolled in a phase 1 trial.

METHODS

The authors reviewed the medical records of 380 pediatric oncology patients (aged <22 years at the time of death) who died during a 3.5-year period. Of these, 103 patients with hematologic malignancies were excluded. A total of 277 patients with a diagnosis of a brain tumor or other solid tumor malignancy were divided into 2 groups based on phase 1 trial enrollment: a phase 1 cohort (PIC; 120 patients) and a non-phase 1 cohort (NPIC; 157 patients). The EOLC characteristics of these 2 cohorts were compared using regression analysis and chi-square testing.

RESULTS

A comparison of patients in the PIC and NPIC revealed no significant differences in either demographic characteristics (including sex, race, religious affiliation, referral origin, diagnosis, or age at diagnosis, with the exception of age at the time of death [P =.03]) or in EOLC indices (such as use or timing of do not attempt resuscitation orders, hospice use or length of stay, forgoing life-sustaining therapies, location of death, time from first EOLC discussion to death, and total number of EOLC discussions).

CONCLUSIONS

The results of the current study of a large cohort of deceased pediatric cancer patients indicate that enrollment on a phase 1 trial does not affect EOLC characteristics, suggesting that quality EOLC can be delivered regardless of phase 1 trial participation.

Practical communication guidance to improve phase 1 informed consent conversations and decision-making in pediatric oncology

BACKGROUND

It can be difficult to explain pediatric phase 1 oncology trials to families of children with refractory cancer. Parents may misunderstand the information presented to them, and physicians may assume that certain topics are covered in the informed consent document and need not be discussed. Communication models can help to ensure effective discussions.

METHODS

Suggestions for improving the informed consent process were first solicited from phase 1 study clinicians via questionnaire. Eight parents who had enrolled their child on a phase 1 pediatric oncology trial were recruited for an advisory group designed to assess the clinicians' suggestions and make additional recommendations for improving informed consent for pediatric phase 1 trials.

RESULTS

A phase 1 communication model was designed to incorporate the suggestions of clinicians and families. It focused on educating parents/families about phase 1 trials at specific time points during a child's illness, but specifically at the point of disease recurrence. An informative phase 1 fact sheet that can be distributed to families was also presented.

CONCLUSIONS

Families who will be offered information regarding phase 1 clinical trials can first receive a standardized fact sheet explaining the general purpose of these early-phase clinical trials. Parental understanding may be enhanced further when oncologists address key themes, beginning at the time of diagnosis and continuing through important decision points during the child's illness. This model should be prospectively evaluated.

Patients in pediatric phase I and early phase II clinical oncology trials at Gustave Roussy: a 13-year center experience

In the European Union, the pediatric medicines regulation in 2007 modified significantly the access to new agents in pediatric oncology. Early oncology trials are still thought to be associated with limited benefit and substantial risk. We report the characteristics and outcome of patients below 21 years enrolled in investigational trials in the Pediatric and Adolescent Department at Gustave Roussy between January 2000 and December 2012. A total of 235 patients (median age, 10.4 [0.8 to 20.7] y) were included in 26 trials (16 cytotoxic and 10 targeted agents) for a total of 260 inclusions. A total of 117 patients (50%) had brain tumors and 68 (29%) had various soft tissue and bone sarcoma. Thirteen of the 106 patients in a phase I trial experienced dose-limiting toxicity. Main severe toxicity was hematologic; none had toxic death. Grade 3 to 4 toxicities were associated with combination trials, cytotoxic agent, and at least 1 previous line of therapy. Thirty patients (12%) had objective response and 42 (16%) had stable disease for >4 months. Median overall survival was 9.0 months (95% CI, 7.5-10.5) and 73% of patients received further anticancer treatment. Phase I to II pediatric oncology trials are safe, associated with clinical benefit, and can be successfully integrated in current relapse strategies.

Prospects and pitfalls of personalizing therapies for sarcomas: from children, adolescents, and young adults to the elderly

Sarcomas are a heterogeneous class of tumors that affect all ages, from children, adolescents, and young adults to the elderly. Within this panoply of tumor subtypes lies the opportunity to bring to bear a vision of personalized medicine in which the fast-paced evolution from the "one gene, one test, one drug" approach to a comprehensive "panomic," multiplex, multianalyte method coupled with advances in bioinformatics platforms can unravel the biology of this disease. The increasingly enlarging repertoire of novel agents provides innumerable prospects in precision medicine. Personalized therapy covers the entire spectrum of cancer care, from risk factor assessment through prevention, risk reduction, therapy, follow-up after therapy, and survivorship care. Challenges remain in implementing the science of precision medicine in the clinic, including providing comprehensive multidisciplinary care and overcoming regulatory and economic hurdles, which must be facilitated within the collaborative framework of academia, industry, federal regulators, and third-party payers.

Improving access to novel agents for childhood leukemia

Leukemia is the most common pediatric cancer. Despite great progress in the development of curative therapy, leukemia remains a leading cause of death from disease in childhood, and survivors are at life-long risk of complications of treatment. New agents are needed to further increase cure rates and decrease treatment-associated toxicities. The complex biology and aggressive nature of childhood leukemia, coupled with the relatively small patient population available for study, pose specific challenges to the development of new therapies. In this review, the authors discuss strategies and initiatives designed to improve access to new agents in the treatment of pediatric leukemia.

The complexity of consenting to clinical research in phase I pediatric cancer studies

The principal aim of phase I studies is to define the recommended dosing of drugs for phase II studies through assessment of drug pharmacokinetics and observation of the drug's toxicity profile. In the setting of pediatric oncology, the use of an experimental drug in phase I study is offered when prognosis is poor. Thus, phase I oncology studies are not given to patients with a primary purpose of an intent to cure. They may offer little to no treatment benefit and carry a potential toxic effect. They may offer other benefits such as improved quality of life and relief of pain, however. Three parties are involved in the informed consent process: the parents, patients, and physicians. Families report hope as the main cause for enrollment. Physicians focus on providing information so families can decide about participation. Physicians also try to maintain hope despite understanding the nature of the disease. This makes the informed consent complicated for all parties involved in the process. The purpose of this review is to discuss the aims of phase I studies in pediatric oncology and to convey the ethical challenges that patients, parents, and physicians are facing when discussing informed consent with potential study participants.

Communication about the risks and benefits of phase I pediatric oncology trials

Introduction

Phase 1 pediatric oncology trials offer only a small chance of direct benefit and may have significant risks and an impact on quality of life. To date, research has not examined discussions of risks and benefits during informed consent conferences for phase 1 pediatric oncology trials. The objective of the current study was to examine clinician and family communication about risks, benefits, and quality of life during informed consent conferences for phase 1 pediatric oncology trials.

Methods

Participants included clinician investigators, parents, and children recruited from 6 sites conducting phase 1 pediatric oncology trials. Eighty-five informed consent conferences were observed and audiotaped. Trained coders assessed discussions of risks, benefits, and quality of life. Types of risks discussed were coded (e.g., unanticipated risks, digestive system risks, death). Types of benefits were categorized as therapeutic (e.g. discussion of how participation may or may not directly benefit child), psychological, bridge to future trial, and altruism.

Results

Risks and benefits were discussed in 95% and 88% of informed consent conferences, respectively. Therapeutic benefit was the most frequently discussed benefit. The impact of trial participation on quality of life was discussed in the majority (88%) of informed consent conferences.

Conclusion

Therapeutic benefit, risks, and quality of life were frequently discussed. The range of information discussed during informed consent conferences suggests the need for considering a staged process of informed consent for phase 1 pediatric oncology trials.

Clinical characteristics and outcomes of pediatric oncology patients with aggressive biology enrolled in phase I clinical trials designed for adults: the university of Texas MD anderson cancer center experience

Background

Children (patients ≤ 18 years of age) are not usually included on pharmaceutical industry sponsored Phase I trials.

Methods

We reviewed the medical records of 40 patients ≤ 18 years treated in ≥ 1 phase I trial at MD Anderson.

Results

The median OS was 8.5 months (95% CI, 5.5-13.2 months). In the multivariate analysis, age ≥15 only predicted increased OS (P = 0.0065), and >3 prior therapies (P = 0.053) predicted decreased OS. The median PFS was 2.8 months (95% CI, 2.3-4.1 months). In the multivariate analysis, independent factors that predicted increased PFS were age ≥15 years (P < 0.001) and prior radiation therapy (P = 0.049); performance status >1 (P < 0.001) and >3 prior therapies (P = 0.002) predicted decreased PFS. RMH score ≥ 2 and MDACC score ≥ 3 were associated with decreased median OS (P = 0.029 and P = 0.031 respectively).

Conclusions

It is feasible to conduct phase I studies in pediatric patients based on adult protocols. In the era of targeted therapy more trials should allow pediatric patients earlier in the drug development especially if deemed safe in adults in early phase trials.

Translational Relevance

Most pharmaceutical industry sponsored trials exclude patients less than 18 years in phase I clinical trials. Even in the era of targeted therapy pediatric patients usually have to wait for most phases of trials to be completed in adults before being allowed to enroll in clinical trials of new therapies, even in the advanced metastatic and relapsed setting. Some investigator initiated phase 1 trials of combinations of US FDA approved agents allow patients less than 18 years. We report the preliminary analyses of the outcomes of pediatric patients enrolled in phase I studies initially designed for adults, but allowing for enrollment of patients under 18.

Patient involvement in informed consent for pediatric phase I cancer research

OBJECTIVE

To examine children's and adolescents' involvement in the informed consent conference for phase I cancer trials and test associations with patient age, ease of understanding, and pressure to participate.

PROCEDURE

Participants included 61 patients aged 7 through 21 years who were offered participation in a phase I trial. Consent conferences were audiotaped, transcribed, and coded for communication between patients and physicians and between patients and parents.

RESULTS

On the basis of word counts, the mean proportion of the consent conference in which the physician was talking to the patient was 36%; the vast majority (73%) of this communication consisted of giving information. Physician-patient communication increased with age, but overall levels of patient-to-physician communication were low (3%). After controlling for patient age, greater physician-to-patient communication was associated with greater ease of understanding.

CONCLUSIONS

The focus on providing information in the context of informed consent may come at the expense of other communication exchanges that are important to patients, especially in the context of end-of-life decisions. Children and adolescents may benefit from the assent process when physicians direct more of their communication to them. Future research should identify the reasons for low patient communication during the consent conference and strategies to enhance their participation in decision making about phase I trial enrollment.

Phase 1 evaluation of EZN-2208, a polyethylene glycol conjugate of SN38, in children adolescents and young adults with relapsed or refractory solid tumors

BACKGROUND

EZN-2208 is a water-soluble PEGylated conjugate of the topoisomerase inhibitor SN38, the active metabolite of irinotecan. Compared to irinotecan, EZN-2208 has a prolonged half-life permitting extended exposure to SN38. EZN-2208 has demonstrated clinical tolerability and antitumor activity in adults with advanced solid tumors. This Phase 1 study evaluated the safety, pharmacokinetics, and preliminary antitumor activity of EZN-2208 in children with relapsed or refractory solid tumors.

PROCEDURE

EZN-2208 was administered as a 1-hour intravenous infusion once every 21 days at five dose levels (12-30 mg/m(2) ). Filgrastim or pegfilgrastim was administered 24-48 hours after treatment with EZN-2208. The rolling-six design was used for dose determination.

RESULTS

Thirty eligible patients (15 females; median [range] age 11.5 years [2-21 years]) were treated with EZN-2208. Dose-limiting diarrhea occurred in one patient receiving 16 mg/m(2) and dose-limiting dehydration was seen in one patient receiving 24 mg/m(2) . At dose levels above 16 mg/m(2) , Grade ≥3 myelosuppression was demonstrated in the majority of patients. Additional adverse events included nausea, vomiting, and fatigue. The maximum tolerated dose was identified as 24 mg/m(2) due to dose-limiting thrombocytopenia in two patients receiving 30 mg/m(2) . Two of nine patients with neuroblastoma who were evaluable for response had partial responses. Five patients (four with neuroblastoma) remained on study for ≥8 cycles.

CONCLUSIONS

EZN-2208 was generally well-tolerated and was associated with clinical benefit in patients with neuroblastoma.

Phase I dose escalation and pharmacokinetic study of oral gefitinib and irinotecan in children with refractory solid tumors

PURPOSE

This phase I study endeavored to estimate the maximum tolerated dose and describe the dose-limiting toxicities (DLTs) of oral irinotecan with gefitinib in children with refractory solid tumors.

METHODS

Oral irinotecan was administered on days 1-5 and 8-12 with oral gefitinib (fixed dose, 150 mg/m(2)/day) on days 1-12 of a 21-day course. The escalation with overdose control method guided irinotecan dose escalation (7 dose levels, range 5-40 mg/m(2)/day).

RESULTS

Sixteen of 19 patients were evaluable, with serial pharmacokinetic studies in ten patients. Diagnoses included osteosarcoma (N = 5), neuroblastoma (N = 3), sarcoma (N = 3), and others (N = 5). Patients received a median of two courses (range 1-20), with at least two patients treated on dose levels 2-7. Three patients had five DLTs; the most common being metabolic (hypokalemia, N = 2 and hypophosphatemia, N = 1) at dose levels two (10 mg/m(2)) and four (20 mg/m(2)). One patient experienced grade 3 diarrhea (40 mg/m(2)). Irinotecan bioavailability was 2.5-fold higher when co-administered with gefitinib, while the conversion rate of irinotecan to SN-38 lactone was unaffected. The study closed due to poor accrual before evaluation of the next recommended irinotecan dose level (35 mg/m(2)). Of 11 patients receiving at least two courses of therapy, three had stable disease lasting two to four courses and one patient maintained a complete response through 18 courses.

CONCLUSIONS

The combination of oral gefitinib and irinotecan has acceptable toxicity and anti-tumor activity in pediatric patients with refractory solid tumors. Pharmacokinetic analysis confirms that co-administration of gefitinib increases irinotecan bioavailability leading to an increased SN-38 lactone systemic exposure.

Hope and persuasion by physicians during informed consent

PURPOSE

To describe hopeful and persuasive messages communicated by physicians during informed consent for phase I trials and examine whether such communication is associated with physician and parent ratings of the likelihood of benefit, physician and parent ratings of the strength of the physician's recommendation to enroll, parent ratings of control, and parent ratings of perceived pressure.

PATIENTS AND METHODS

Participants were children with cancer (n = 85) who were offered a phase I trial along with their parents and physicians. Informed consent conferences (ICCs) were audiotaped and coded for physician communication of hope and persuasion. Parents completed an interview (n = 60), and physicians completed a case-specific questionnaire.

RESULTS

The most frequent hopeful statements related to expectations of positive outcomes and provision of options. Physicians failed to mention no treatment and/or palliative care as options in 68% of ICCs and that the disease was incurable in 85% of ICCs. When physicians mentioned no treatment and/or palliative care as options, both physicians and parents rated the physician's strength of recommendation to enroll in the trial lower.

CONCLUSION

Hopes and goals other than cure or longer life were infrequently mentioned, and a minority of physicians communicated that the disease was incurable and that no treatment and/or palliative care were options. These findings are of concern, given the low likelihood of medical benefit from phase I trials. Physicians have an important role to play in helping families develop alternative goals when no curative options remain.

Toxicity and outcome of children and adolescents participating in phase I/II trials of novel anticancer drugs: the Royal Marsden experience

Early phase trials are crucial in developing new therapies for poor prognosis childhood malignancies. Outcomes and toxicities of children treated on phase I/II trials at the Royal Marsden, one of the largest pediatric oncology early phase trial units in Europe, were examined to provide a baseline dataset and generate hypotheses. All patients recruited over a 10-year period to December 2011 were included. Variables including baseline characteristics, time on study, survival, toxicities, and admissions were collected. Seventy-two patients were recruited to 21 trials (5 phase I, 16 phase II; overall 12 involved molecularly targeted agents). Median age at consent was 12.4 years. Dose-limiting toxicities were rare in phase I trial participants (2 of 15 evaluable patients, 13%); the most common reason for leaving trials was disease progression (76%), rather than drug toxicity (1.7%). Median time on trial was 1.3 months (phase I patients) and 3.3 months (phase II). Early phase trials in children are safe and unexpected toxic side effects are infrequent. Patients and their families are willing to travel to access novel therapies, although the overall prognosis for these individuals is poor. Continued expansion of the portfolio is needed ultimately to improve the outcomes for those with resistant disease.

New drug development in childhood cancer

PURPOSE OF REVIEW

Future advances in childhood cancer treatment will pivot on developing biology-driven new drug development pathways that build on current knowledge of oncogenic pathways; however, we need to address major barriers to accessing new drugs for clinical evaluation in childhood cancers.

RECENT FINDINGS

Through legislative change, substantial incentives to the pharmaceutical industry to invest in the ultra-rare diseases, such as childhood cancers, have encouraged greater engagement with paediatric oncology drug development consortia. Disappointingly, this has not translated into paediatric-focussed drug development. Adult disease-driven drug development will continue to dominate until biology/target-driven approaches prevail.There are specific challenges to undertaking early drug development trials in children with incurable disease. The balance between risk and benefit for a child participating in trials wherein the chance of clinical benefit is indeterminate has the potential for unrealistic optimism by both physicians and families. Importantly, innovative trial designs that assess safety and maximize information on potential efficacy from small patient numbers are needed.

SUMMARY

International collaboration in early phase trial consortia addresses these challenges. Academic networks concentrating early phase trials expertise and delivery of innovative trial designs will maximize appropriate selection of drugs that can translate into therapeutic advantage when incorporated into standard care.

Physician perceptions and beliefs of phase I trials in pediatric oncology

The identification and referral of candidate patients for phase I trials relies heavily on pediatric oncologists who must balance their own perceptions of phase I trials with the desires of the patient and his/her family. A survey was sent to 419 physicians practicing pediatric oncology at 30 different institutions. Results indicated significant differences between physicians who practiced at institutions that participated in phase I consortia versus those who did not. The findings of the survey may be used to enhance the design and execution of phase I trials and to educate oncologists about the goals of phase I trials.

Adolescent perspectives on phase I cancer research

BACKGROUND

The aim of this study was to examine adolescent patients' perspectives on their understanding and decision making about a pediatric phase I cancer study.

PROCEDURE

Participants included adolescents ages 14-21 years with cancer (N = 20), all of whom attended a phase I study consent conference. Participants responded to closed- and open-ended questions on a verbally administered structured interview, which assessed aspects of understanding and decision making about the phase I study.

RESULTS

All participants decided to enroll in the phase I study. The majority of participants understood that participation was voluntary, entailed risks, and that they could withdraw. Most also believed that participation in the phase I study would increase the length of their lives. The most frequent reasons for enrolling were positive clinical benefit, needing an option, impact on quality of life, and few side effects or fewer than those of current or past treatments. Eighty-five percent of participants reported that they themselves made the final decision about enrollment in the phase I study.

CONCLUSIONS

Most participants hoped or expected that the phase I study would provide a direct benefit (increased survival time or cure) and reported that they themselves were the final decision-maker about enrollment. Clinicians may underestimate the role of adolescents, especially if they believe that parents typically make such decisions. Future research should assess the actual participation of children and adolescents during the informed consent process and explore the role of hope in their decision making about phase I studies.

A simulation-based comparison of the traditional method, Rolling-6 design and a frequentist version of the continual reassessment method with special attention to trial duration in pediatric Phase I oncology trials

The traditional method (TM), also known as the 3+3 up-and-down design, and the continual reassessment method (CRM) are commonly used in Phase I oncology trials to identify the maximum tolerated dose (MTD). The rolling-6 is a relative newcomer which was developed to shorten trial duration by minimizing the period of time during which the trial is closed to accrual for toxicity assessment. In this manuscript we have compared the performance of these three approaches via simulations not only with respect to the usual parameters such as overall toxicity, sample size and percentage of patients treated at doses above the MTD but also in terms of trial duration and the dose chosen as the MTD. Our results indicate that the toxicity rates are comparable across the three designs, but the TM and the rolling-6 tend to treat a higher percentage of patients at doses below the MTD. With respect to trial duration, rolling-6 leads to shorter trials compared to the TM but not compared to the CRM. Additionally, the doses identified as the MTD by the TM and the rolling-6 differ in a large percentage of trials. Our results also indicate that the body surface area-based dosing used in pediatric trials can make a difference in dose escalation/de-escalation patterns in the CRM compared to the cases where such variations are not taken into account in the calculations, even leading to different MTDs in some cases.

Operating characteristics of two independent sample design in phase I trials in paediatric oncology

PURPOSE

The European medicines agency (EMEA) has stated that the degree of pre-treatment could modify the patient's tolerance to new treatments in paediatric oncology. It is current practice to divide a phase I trial into two groups to identify the maximum tolerated dose (MTD) in each group separately. The aim of this study was to investigate the relevance of this approach.

METHODS

We reanalysed a large phase I trial of Irinotecan that included 80 children (32 heavily pretreated patients and 48 less heavily pretreated). An extended simulation study was performed to investigate the robustness of the conclusions in the context of small sample sizes. Dose recommendations were studied according to scenarios with group differences, as measured by odds ratio (OR), ranging from 1 (no difference) to 10 (large difference) and sample sizes increasing from 20 x 2 to 60 x 2 patients.

RESULTS

This study shows a high risk of misidentification of the MTD in each of the two groups, regardless of the group difference. With a group difference corresponding to OR=8 and balanced sample sizes (20 x 2 patients), the same MTD was identified in 11% of the simulations. Even with larger sample sizes (40 x 2 patients), this figure reached 24% for OR=3. There is also a very high risk of identifying two different MTD (52% for 40 x 2 patients) although the risk is similar in both groups.

CONCLUSIONS

Two independent sample designs in paediatric phase I trials should be avoided or reserved to limited situations when there is a strong rationale possibly based on adult data.

Characteristics of children enrolled in treatment trials for NF1-related plexiform neurofibromas

OBJECTIVE

To describe the characteristics of children enrolled in treatment trials for neurofibromatosis type 1 (NF1)-related plexiform neurofibroma (PN), PN tumor burden, PN-related complications, and treatment outcomes and to highlight the differences between characteristics of children with NF1 vs children with cancers entered on early phase drug trials.

METHODS

Pre-enrollment characteristics and complications of PN were retrospectively analyzed in a cohort of 59 children with NF1-related PN treated on 1 of 7 clinical trials at the NIH between 1996 and 2007. Outcome was analyzed in a subset of 19 patients enrolled in phase I trials. Comparisons to children with cancer were made from a similar analysis performed recently.

RESULTS

The median age at enrollment was 8 years. The median PN volume was 555 mL. Most patients had no prior chemotherapy or radiation, but nearly half had previous surgery for PN. PN-associated complications and NF1 manifestations were common, including pain (53%), other tumors (18%), and hypertension (8%). Investigational drug therapy was well tolerated. A median of 10 treatment cycles was administered. Patients with NF1-related PN were younger, had better performance score, had less prior therapy, and remained on study longer than cancer patients.

CONCLUSIONS

Children with NF1-related plexiform neurofibroma (PN) enrolled in clinical trials had large tumors with substantial morbidity. Clinical trials in these children provide information about drug tolerance, cumulative toxicity, and pharmacokinetics in a younger population than early phase pediatric cancer trials. This report may aid in the evaluation of the applicability of traditional pediatric cancer trial designs and endpoints for NF1-related PN.

Evaluation of agile designs in first-in-human (FIH) trials--a simulation study

The aim of the investigation was to evaluate alternatives to standard first-in-human (FIH) designs in order to optimize the information gained from such studies by employing novel agile trial designs. Agile designs combine adaptive and flexible elements to enable optimized use of prior information either before and/or during conduct of the study to seamlessly update the study design. A comparison of the traditional 6 + 2 (active + placebo) subjects per cohort design with alternative, reduced sample size, agile designs was performed by using discrete event simulation. Agile designs were evaluated for specific adverse event models and rates as well as dose-proportional, saturated, and steep-accumulation pharmacokinetic profiles. Alternative, reduced sample size (hereafter referred to as agile) designs are proposed for cases where prior knowledge about pharmacokinetics and/or adverse event relationships are available or appropriately assumed. Additionally, preferred alternatives are proposed for a general case when prior knowledge is limited or unavailable. Within the tested conditions and stated assumptions, some agile designs were found to be as efficient as traditional designs. Thus, simulations demonstrated that the agile design is a robust and feasible approach to FIH clinical trials, with no meaningful loss of relevant information, as it relates to PK and AE assumptions. In some circumstances, applying agile designs may decrease the duration and resources required for Phase I studies, increasing the efficiency of early clinical development. We highlight the value and importance of useful prior information when specifying key assumptions related to safety, tolerability, and PK.

Continual reassessment method vs. traditional empirically based design: modifications motivated by Phase I trials in pediatric oncology by the Pediatric Brain Tumor Consortium

In this article we provide additional support for the use of a model-based design in pediatric Phase I trials and present our modifications to the continual reassessment method (CRM), which were largely motivated by specific challenges we encountered in the context of the Pediatric Brain Tumor Consortium trials. We also summarize the results of our extensive simulations studying the operating characteristics of our modified approach and contrasting it to the empirically based traditional method (TM). Compared to the TM, our simulations indicate that the modified version of CRM is more accurate, exposes fewer patients to potentially toxic doses, and tends to require fewer patients. Further, the CRM-based MTD has a consistent definition across trials, which is important, especially in a consortium setting where multiple agents are being tested in studies that are often running simultaneously and accruing from the same patient population.

Characteristics and outcome of pediatric patients enrolled in phase I oncology trials

PURPOSE

To describe the characteristics of pediatric subjects who enroll in phase I trials, to determine the associations between pre-enrollment characteristics and the risk for toxicity, and to analyze response and survival outcomes.

EXPERIMENTAL DESIGN

Pre-enrollment characteristics and study outcomes were retrospectively analyzed for children with refractory solid tumors treated in one of 16 phase I trials with similar eligibility criteria at the National Cancer Institute between 1992 and 2005.

RESULTS

The 262 subjects analyzed had received a median of two (range, 0-9) prior chemotherapy regimens, and were on one (range, 0-12) concomitant medication. The Eastern Cooperative Oncology Group performance status scores for subjects were 0 (29%), 1 (48%), and 2 (19%); 19% had received a prior stem cell transplantation and 73% had received prior radiation. Approximately 90% of subjects were evaluable for the primary trial endpoints (toxicity and pharmacokinetics). Seventeen percent of subjects experienced a dose-limiting toxicity (DLT), 5% discontinued the study drug because of toxicity, and a drug-related death occurred in one subject (0.4%). Variables associated with a higher risk for developing a DLT, by multiple logistic regression analysis, were drug dose and prior radiation, for myelosuppressive agents, and drug dose and performance status, for nonmyelosuppressive agents. The complete and partial response rate was 4%; however, 17% of subjects had stable disease (received three or more cycles). The median overall survival time from the time of enrollment was five months.

CONCLUSIONS

Primary trial objectives are achieved in approximately 90% of subjects with the standard phase I trial design and eligibility criteria despite the intensification of frontline and salvage therapies in pediatric subjects with cancer.

Bone-marrow relapse in paediatric acute lymphoblastic leukaemia

Marrow relapse is the major obstacle to cure for 10-15% of young patients with acute lymphoblastic leukaemia (ALL). Recent investigations into the biology of minimal residual disease indicate that many early relapses derive from residual cells present at first diagnosis, but some late relapses might represent new mutations in leukaemic cells not eliminated by conventional therapy. Treatment of marrow relapse involves higher doses and more intensive schedules of the drugs used for initial therapy with or without haemopoietic stem cell transplantation. In most reports, transplantation is better than continuation chemotherapy in early marrow relapse, but its role in later relapse is less clear. Current therapy cures 10% of patients with early marrow relapses and 50% of those with late relapses, but outcomes have changed little in the past two decades. Understanding the molecular biology of ALL underlies development of improved risk stratification and new therapies. Although better drugs are needed, introduction of new agents into clinical trials in paediatric disease has been difficult. Innovative trial designs and use of valid surrogate endpoints may expedite this process.

A SAS-based solution to evaluate study design efficiency of phase I pediatric oncology trials via discrete event simulation

Previous exploration of oncology study design efficiency has focused on Markov processes alone (probability-based events) without consideration for time dependencies. Barriers to study completion include time delays associated with patient accrual, inevaluability (IE), time to dose limiting toxicities (DLT) and administrative and review time. Discrete event simulation (DES) can incorporate probability-based assignment of DLT and IE frequency, correlated with cohort in the case of DLT, with time-based events defined by stochastic relationships. A SAS-based solution to examine study efficiency metrics and evaluate design modifications that would improve study efficiency is presented. Virtual patients are simulated with attributes defined from prior distributions of relevant patient characteristics. Study population datasets are read into SAS macros which select patients and enroll them into a study based on the specific design criteria if the study is open to enrollment. Waiting times, arrival times and time to study events are also sampled from prior distributions; post-processing of study simulations is provided within the decision macros and compared across designs in a separate post-processing algorithm. This solution is examined via comparison of the standard 3+3 decision rule relative to the "rolling 6" design, a newly proposed enrollment strategy for the phase I pediatric oncology setting.

Shortening the timeline of pediatric phase I trials: the rolling six design

PURPOSE

To shorten the study conduct timeline of pediatric phase I oncology trials by employing a novel trial design.

METHODS

A comparison of the traditional 3 + 3 patients per cohort, phase I trial design with a novel, rolling six design was performed by using discrete event simulation. The rolling six design allows for accrual of two to six patients concurrently onto a dose level based on the number of patients currently enrolled and evaluable, the number experiencing dose-limiting toxicity (DLT), and the number still at risk of developing a DLT. Clinical trial simulations (n = 1,000) were based on historical data and were performed using SAS 9.1.3 (SAS Institute, Cary, NC). Study timelines and patient numbers were determined for each design, and safety was assessed as a function of the number of DLTs observed.

RESULTS

In twelve completed historical studies, the median time to study completion was 452 days (range, 220 to 606 days); number of evaluable participants enrolled was 22 (range, 11 to 33), and DLTs occurring per study was three (range, 0 to 5). In 1,000 study simulations, in which the average time to new patient accrual was 10 days, the average +/- standard deviation (SD) time to study completion was 294 +/- 75 days for the rolling six design versus 350 +/- 84 days for the 3 + 3 design, whereas the number of DLTs per study was the same (average +/- SD, 3.3 +/- 1.1 v 3.2 +/- 1.1 for the rolling six and 3 + 3 designs, respectively).

CONCLUSION

The rolling six design may significantly decrease the duration of pediatric phase I studies without increasing the risk of toxicity. The design will be tested prospectively in upcoming Children's Oncology Group phase I trials.

Good clinical practice and the conduct of clinical studies in pediatric oncology

This article discusses the principles that guide good clinical practice standards, with particular emphasis on how they to relate to pediatric oncology research and recent efforts at harmonization. The authors review the clinical trials process and the roles of the participants, highlighting the pivotal role of the clinical investigator and the research team, and briefly review the historical aspects of drug development regulations in the United States and the current regulatory paths for pediatric oncology drug development. Where relevant, historical events that underlie many of the regulations and their current applications are described, and practical examples are provided.

Venlafaxine in the treatment of children and adolescents with attention-deficit/hyperactivity disorder

OBJECTIVE

The objectives of this pilot study were to explore the changes in symptom severity, tolerability, and the pharmacodynamics of venlafaxine treatment in youths with attention-deficit/hyperactivity disorder (ADHD).

METHODS

This was a 2-week, open-label, outpatient trial of venlafaxine in children and adolescents, ages 5-17 years, with ADHD. Three dosing strata, 0.5, 1.0, and 2.0 mg/kg per day, were examined. ADHD symptom severity and improvement assessments included the ADHD Rating Scale (ARS-IV) and the Clinical Global Impressions Scale (CGI). During this study, venlafaxine, O-desmethylvenlafaxine (ODV), norepinephrine, and serotonin concentrations were obtained.

RESULTS

Thirty-eight participants (33 males) were treated in this trial. Overall, parent-completed and teacher-completed ARS-IV total scores showed a statistically significant positive change at the end of the study when compared to baseline (p < 0.05). Significant increases in plasma venlafaxine concentrations were observed at day 15 when compared to day 8 (p = 0.04). In addition, plasma norepinephrine and serotonin concentrations were found to be significantly decreased from baseline at end of study (p < 0.05). Four patients ended participation in the study prematurely: lost to follow up (n = 2), withdrawal of consent (n = 1), and worsening of ADHD symptoms after 8 days of treatment (n = 1). There were no discontinuations due to other adverse events.

CONCLUSIONS

Venlafaxine appeared to offer some benefit and appears to be relatively safe for the short-term treatment of ADHD in this open-label trial. The pharmacodynamics of venlafaxine in youths are consistent with serotonergic and neuradrenergic modulation.