Potential utility of a longitudinal relative dose intensity of molecularly targeted agents in phase 1 dose-finding trials

Racial differences in longitudinal toxicities of anticancer agents in early phase cancer clinical trials

BACKGROUND

Racial differences have been reported in toxicity outcomes for anticancer drug treatments. However, these observations were often from studies with small sample sizes, and many only reported the maximum grade of toxicity and no longitudinal information. This current analysis aims to investigate racial differences in longitudinal toxicities using a large-scale clinical trials database.

METHODS

Early-phase clinical trials sponsored by the Cancer Therapy Evaluation Program at the National Cancer Institute, USA, that evaluated cytotoxic drugs and molecularly targeted agents between March 2000 and December 2012 were studied. Race was categorized as White, Black or African-American, and Asian. Each toxicity's grade prevalence, mean grade at each cycle, and time to develop grade 2 or higher toxicity was evaluated.

RESULTS

In total, 25,442 patients from 697 trials were included in this study. The number of patients categorized as White, Black, and Asian designations was 22,756 (89%), 1874 (7%), and 812 (3%), respectively. Notable findings include the rate of any grade of diarrhea in Black people was 26% and 21% lower than that of White and Asian people. The median time to the first grade 2 or higher event was 6 cycles in White people, 8 in Black people, and 6 in Asian people. The rate of any grade hyperglycemia was significantly higher in Asian people.

CONCLUSIONS

Although we identified several racial differences in longitudinal toxicities, most were of generally lower grade. Further study is needed to clarify the cause of racial differences in treatment-associated toxicities.

Evaluation of toxicities related to novel therapy in clinical trials for women with gynecologic cancer

BACKGROUND

Women with gynecologic cancer may be at increased risk for adverse events (AEs) due to peritoneal disease burden and prior treatment (surgery, chemotherapy, and pelvic radiotherapy). This study compared the toxicity profiles of patients with and without gynecologic cancer enrolled in phase 1 trials.

METHODS

This was a retrospective analysis of the National Cancer Institute phase 1 database for all trials enrolling 1 or more patients with gynecologic cancer over 2 decades (1995-2015). Clinical parameters collected included demographics, cancer history, trial information, AEs, and responses. AEs (according to the Common Terminology Criteria for Adverse Events) were documented for each patient during treatment, and they were counted once and analyzed on the basis of the highest grade and drug attribution. Multiple regression models were used to compare AEs at the baseline and during treatment.

RESULTS

A total of 4269 patients enrolled in 150 trials were divided into 3 groups: 1) women with gynecologic cancer (n = 685), 2) women with nongynecologic cancer (n = 1698), and 3) men with cancer (n = 1886). The median age was 58 years. The mean number of total AEs reported during treatment was highest for women with gynecologic cancer (17.1 vs 14.7 vs 13.5; P < .001), even though they were similar at the baseline (7.0 vs 7.4 vs 7.0; P = .09). The mean number of drug-related AEs was also highest for women with gynecologic cancer (8.3 vs 6.9 vs 6.2; P < .001). Grade 3 to 5 AEs were similar (2.3 vs 2.3 vs 2.1); however, grade 2 AEs were more frequent in women with gynecologic cancer (4.6 vs 3.9 vs 3.5). Treatment discontinuations due to AEs were similar (9% vs 9% vs 10%).

CONCLUSIONS

Women with gynecologic cancer experienced more frequent low-grade AEs during treatment, and this warrants attention to support their symptom burden. Study dose management should be considered for recurrent grade 2 AEs, particularly during continuous therapy.

Pragmatic dose-escalation methods incorporating relative dose intensity assessment for molecularly targeted agents in phase I trials

The recommended phase 2 doses of molecularly targeted agents, determined by using an ordinal dose-finding method that only uses toxicity data at first cycle, may not be optimal. Some researchers have proposed the use of relative dose intensity that can account for late-onset, cumulative, and low-grade toxicities to determine the recommended phase 2 dose (RP2D). In this study, we proposed two dose escalation methods based on the observed relative dose intensities (RDIs) between the pre-specified intervals (cycles) for toxicity evaluation used in combination with DLT evaluation in the first cycle. First, we propose the modified 3 + 3 design that incorporates longitudinal RDI assessment. Second, we propose the sequential assessment method for longitudinal RDI (SARDI) to achieve faster dose escalation compared to that of the modified 3 + 3 design. Simulation studies demonstrated that the SARDI was, in many cases, superior to the ordinal and modified 3 + 3 designs in respect to the selection rate of true RP2D and study period. The two proposed methods could also in some cases decrease the average number of patients enrolled in the trial compared to that of the ordinary 3 + 3 design. Incorporation of the RDI assessment into the 3 + 3 design is not difficult and does not require the use of complex statistical techniques. Therefore, we believe that investigators who routinely use the 3 + 3 design in practice can easily use our proposed methods.

Potential utility of a longitudinal relative dose intensity of molecularly targeted agents in phase 1 dose-finding trials

Phase 1 trials of molecularly targeted agents (MTA) often do not use toxicity data beyond the first cycle of treatment to determine a recommended phase 2 dose (RP2D). We investigated the potential utility of longitudinal relative dose intensity (RDI) that may be a better new way of determining a more accurate RP2D as a lower dose that is presumably more tolerable over the long term without compromising efficacy. All consecutive patients who were initially treated using a single MTA at the conventional RP2D or at one level lower dose (OLLD) of that RP2D in 9 phase 1 trials sponsored by the National Cancer Institute were included. The associations between longitudinal RDI, time to first progression, and response rate were analyzed. The RDI of the conventional RP2D group were maintained a rate of ≥70% throughout 10 cycles, and were higher than those of the OLLD group, although in both groups the RDI gradually decreased with additional treatment cycles. The RP2D group was similar to the OLLD group with respect to time to first progression and response rate. In both groups, however, the decreasing RDI over time was significantly associated with shorter time to first disease progression; therefore, the longitudinal RDI, which takes into account lower grade toxicity occurrences, may be useful in determining a more desirable dose to use in phase 2 and 3 studies.