Methodologic guidelines for the design of high-dose chemotherapy regimens

A review of dose escalation for FDA-approved products treating solid tumors and hematological malignancies in first-in-human trials

First-in-human (FIH) dose-escalation trials on oncology should prioritize safety and emphasize efficacy. We reviewed the FIH trials of 67 anti-tumor products approved by the Food and Drug Administration between 2018 and 2023 and found that the "3 + 3" design remains the predominant dose-escalation method (66.2%). The number of patients receiving sub-therapeutic doses is positively correlated with the maximum tolerated dose (MTD) or maximum dose (MD) to starting dose ratio (P = 0.056) and the number of dose levels in trials (P < 0.001). In addition, the proportion of products with a high ratio in antibody drugs is higher than that in small molecules (P < 0.001). The MTD or MD exceeded the label dose by three or more doses in 22.03% of the products. In conclusion, optimizing the starting dose selection method, refining the way of determining doses, and finding alternative indicators to replace toxicity as the endpoints will increase the effectiveness and broaden the beneficiary scope.

Development of consensus-driven SPIRIT and CONSORT extensions for early phase dose-finding trials: the DEFINE study

BACKGROUND

Early phase dose-finding (EPDF) trials are crucial for the development of a new intervention and influence whether it should be investigated in further trials. Guidance exists for clinical trial protocols and completed trial reports in the SPIRIT and CONSORT guidelines, respectively. However, both guidelines and their extensions do not adequately address the characteristics of EPDF trials. Building on the SPIRIT and CONSORT checklists, the DEFINE study aims to develop international consensus-driven guidelines for EPDF trial protocols (SPIRIT-DEFINE) and reports (CONSORT-DEFINE).

METHODS

The initial generation of candidate items was informed by reviewing published EPDF trial reports. The early draft items were refined further through a review of the published and grey literature, analysis of real-world examples, citation and reference searches, and expert recommendations, followed by a two-round modified Delphi process. Patient and public involvement and engagement (PPIE) was pursued concurrently with the quantitative and thematic analysis of Delphi participants' feedback.

RESULTS

The Delphi survey included 79 new or modified SPIRIT-DEFINE (n = 36) and CONSORT-DEFINE (n = 43) extension candidate items. In Round One, 206 interdisciplinary stakeholders from 24 countries voted and 151 stakeholders voted in Round Two. Following Round One feedback, one item for CONSORT-DEFINE was added in Round Two. Of the 80 items, 60 met the threshold for inclusion (≥ 70% of respondents voted critical: 26 SPIRIT-DEFINE, 34 CONSORT-DEFINE), with the remaining 20 items to be further discussed at the consensus meeting. The parallel PPIE work resulted in the development of an EPDF lay summary toolkit consisting of a template with guidance notes and an exemplar.

CONCLUSIONS

By detailing the development journey of the DEFINE study and the decisions undertaken, we envision that this will enhance understanding and help researchers in the development of future guidelines. The SPIRIT-DEFINE and CONSORT-DEFINE guidelines will allow investigators to effectively address essential items that should be present in EPDF trial protocols and reports, thereby promoting transparency, comprehensiveness, and reproducibility.

TRIAL REGISTRATION

SPIRIT-DEFINE and CONSORT-DEFINE are registered with the EQUATOR Network ( https://www.equator-network.org/ ).

Dose-finding designs for cumulative toxicities using multiple constraints

This article addresses the concern regarding late-onset dose-limiting toxicities (DLT), moderate toxicities below the threshold of a DLT and cumulative toxicities that may lead to a DLT, which are mostly disregarded or handled in an ad hoc manner when determining the maximum tolerated dose (MTD) in dose-finding cancer clinical trials. An extension of the Time-to-Event Continual Reassessment Method (TITE-CRM) which allows for the specification of toxicity constraints on both DLT and moderate toxicities, and can account for partial information is proposed. The method is illustrated in the context of an Erlotinib dose-finding trial with low DLT rates, but a significant number of moderate toxicities leading to treatment discontinuation in later cycles. Based on simulations, our method performs well at selecting the dose level that satisfies both the DLT and moderate-toxicity constraints. Moreover, it has similar probability of correct selection compared to the TITE-CRM when the true MTD based on DLT only and the true MTD based on grade 2 or higher toxicities alone coincide, but reduces the probability of recommending a dose above the MTD.

Phase I Study of Clofarabine and 2-Gy Total Body Irradiation as a Nonmyeloablative Preparative Regimen for Hematopoietic Stem Cell Transplantation in Pediatric Patients with Hematologic Malignancies: A Therapeutic Advances in Childhood Leukemia Consortium Study

Clofarabine is a purine nucleoside analog with immunosuppressive and antileukemic activity and its inclusion in reduced-intensity regimens could potentially improve outcomes. We performed a prospective phase I study of clofarabine combined with 2 Gy total body irradiation (TBI) as a nonmyeloablative preparative regimen for allogeneic stem cell transplantation in pediatric patients who were considered at high risk of mortality from standard myeloablative regimens. The main goal of the study was to delineate the maximum feasible dose (MFD) of clofarabine in combination with 2 Gy TBI. Eighteen patients, 1 to 21 years of age and in complete remission, were enrolled in 2 strata (matched related donor and unrelated donor) and evaluated for day100 dose-limiting events (DLE) (nonengraftment, nonrelapse mortality [NRM], and severe renal insufficiency) after receiving clofarabine at the starting dose level of 40 mg/m². All 6 patients (3 in each stratum) engrafted with no day 100 DLE seen in the first cohort. The dose was increased to 52 mg/m² in the next and an expanded cohort (total of 12 patients) and no DLE were observed at day 100 and at the 1-year study endpoint. The regimen was well tolerated with transient transaminitis and gastrointestinal and skin reactions as the common reversible toxicities observed with clofarabine. The dose of 52 mg/m² of clofarabine was deemed the MFD. Disease relapse led to mortality in 6 (33%) patients during follow-up with 1-year event-free survival and overall survival of 60% (95% confidence interval [CI], 34 to 79) and 71% (95% CI, 44 to 87), respectively. This regimen leads to successful engraftment using both related and unrelated donors with exceptionally low rates of NRM.

Pharmacodynamics (PD) and pharmacokinetics (PK) of E7389 (eribulin, halichondrin B analog) during a phase I trial in patients with advanced solid tumors: a California Cancer Consortium trial

BACKGROUND

The California Cancer Consortium completed a phase I trial of E7389 (eribulin mesylate), an analog of the marine natural product halichondrin B. This trial was to determine the pharmacodynamics, pharmacokinetics, and MTD of E7389 administered by bolus injection weekly for 3 weeks out of four.

METHODS

This trial included a rapid titration design. Real-time pharmacokinetics were utilized to guide dose escalation. Initially, single-patient cohorts were enrolled with intra- and inter-patient dose doubling. The second phase was a standard 3 + 3 dose escalation schedule. At the MTD, a cohort of patients was enrolled for target validation studies (separate manuscript). The starting dose was 0.125 mg/m(2), and doses were doubled within and between patients in the first phase. Blood and urine sampling for E7389 pharmacokinetics was performed on doses 1 and 3 of cycle 1. Levels were determined using a LC/MS/MS assay.

RESULTS

Forty patients were entered. Thirty-eight were evaluable for toxicity and 35 for response. The rapid escalation ended with a grade 3 elevation of alkaline phosphatase at 0.5 mg/m(2)/week. The second phase ended at 2.0 mg/m(2)/week with dose-limiting toxicities of grades 3 and 4 febrile neutropenia. Other toxicities included hypoglycemia, hypophosphatemia, and fatigue. The MTD was 1.4 mg/m(2)/week. Responses included four partial responses (lung cancer [2], urothelial [1], and melanoma [1]).

CONCLUSIONS

E7389 was well tolerated in this trial with the major toxicity being myelosuppression. PD shows that E7389 induces significant morphologic changes (bundle formation) in the microtubules of peripheral blood mononuclear cells and tumor cells in vivo. The data suggest that lower intra-tumoral levels of β-tubulin III or higher intra-tumoral levels of MAP4 may correlate with response to E7389, while lower intra-tumoral levels of stathmin may be associated with progression. PK data reveal that E7389 exhibits a tri-exponential elimination from the plasma of patients receiving a rapid i.v. infusion. At sub-toxic doses, plasma concentrations of E7389 are maintained well above the levels required for activity in vitro for >72 h.

How First-Time-in-Human Studies Are Being Performed: A Survey of Phase I Dose-Escalation Trials in Healthy Volunteers Published Between 1995 and 2004

First-time-in-human studies are small, time-lagged dose-escalation studies including volunteer subjects evaluating safety and tolerability. There is little consensus in the design of a first-time-in-human study, and it is difficult to get an overview of studies performed. One hundred five studies comprising 3323 healthy volunteers published in the 5 major clinical pharmacology journals since 1995 were analyzed. The average trial was placebo controlled, double blind including 32 subjects at 5 dose levels but with great variation in cohort size and dose-escalation method. The parallel single-dose design was the most common design, with the crossover designs being more frequent in the early publications. Despite discussions on the optimization of phase I trials, little seems to be happening. The development of study designs and evaluation methods for cancer trials is extensive, but formal statistically based methods and more scientific study designs are unusual in phase I dose-escalation trials in healthy volunteers.

A survey of the way pharmacokinetics are reported in published phase I clinical trials, with an emphasis on oncology

BACKGROUND AND OBJECTIVE

During the drug development process, phase I trials are the first occasion to study the pharmacokinetics of a drug. They are performed in healthy subjects, or in patients in oncology, and are designed to determine a safe and acceptable dose for the later phases of clinical trials. We performed a bibliographic survey to investigate the way pharmacokinetics are described and reported in phase I clinical trials.

METHODS

We performed a MEDLINE search to retrieve the list of papers published between 2005 and 2006 and reporting phase I clinical trials with a pharmacokinetic study. We used a spreadsheet to record general information concerning the study and specific information regarding the pharmacokinetics, such as the sampling times, number of subjects and method of analysis.

RESULTS

The search yielded 349 papers, of which 37 were excluded for various reasons. Nearly all of the papers in our review concerned cancer studies, although this was not a requirement in the search. Consistent with the selection process, 84% papers explicitly stated pharmacokinetics as an objective of the study. The methods section usually included a description of the pharmacokinetics (88%), but 10% of the papers provided no information concerning the methods used for the pharmacokinetics and in 2% the description was only partial. The analytical method was usually basic, with non-compartmental or purely descriptive methods. Observed concentrations and areas under the concentration-time curves were the pharmacokinetic variables most often reported. The results of the pharmacokinetic study were frequently reported in a separate paragraph of the results section, and only 22% of the studies related the pharmacokinetic findings to other results from the study, such as toxicity or efficacy. In addition, important information such as the number of subjects included in the pharmacokinetic study or the pharmacokinetic sampling scheme was sometimes not reported explicitly.

CONCLUSION

Concerns about the decreasing cost-effectiveness of the drug development process prompted the regulatory authorities to recently recommend better integration of all available information - including, in particular, pharmacokinetics - in this process. In our review, we found that this information was often either missing or incomplete, which hinders that objective. We suggest several improvements in the design and the reporting of the methods and results of these studies, to ensure that all relevant information has been included. Pharmacokinetic findings should also be integrated into the broader perspective of drug development, through the study of their relationship with toxicity and/or efficacy, even in the early phase I stages.

Evaluation of the cohort size in phase I dose escalation trials based on laboratory data

A survey of Phase I dose escalation trials published since 1995 shows that there is great disparity in all aspects of the design of the studies, and the cohort sizes range from 2 to 16 subjects with a great variety in the distribution between active and placebo-treated subjects. This study investigates the impact of the cohort size on Type I error and power in Phase I dose escalation trials based on laboratory data, with the hospitalization-induced increase in hepatic enzyme levels taken into consideration. The power of a Phase I dose escalation trial is very low, and only events with a very high probability of occurrence are detectable with acceptable power. For studies with cohort sizes smaller than 6 active subjects, there is much to gain with the inclusion of 1 extra subject, but for more than 10 subjects, little is gained by increasing the cohort size. With increasing cohort sizes, the probability of spontaneous non-drug-related events also increases, and this background rate needs to be considered when evaluating the trial.