Sequential boundaries approach in clinical trials with unequal allocation ratios

e14582 Background: Patients enrollment in cancer clinical trials has traditionally been limited to an equal distribution between cases and controls. Some clinical trials have an unequal distribution between the case and control arm. Although such unequal allocation is uncommon it has certain advantages and disadvantages to it. The trend and proportion of cancer clinical trials that have an unequal allocation has not been studied. Methods: Data about cancer clinical trials was extracted from clinical trials.gov. The query included phase 3 trials which included adults and were conducted between 2010 to 2017. Only clinical trials that were either completed or active – but not recruiting were included. T test was used to determine statistical difference between different subgroups. Results: 601 clinical trials were identified of which 356 trials with two arms and 47 trials with 3+ arms were identified. Amongst the eligible 298 trials with two arms, there were 216 trials with equal allocation (1:1) and 82 trials with unequal allocation. Amongst the eligible 29 trials with 3+ arms; there were 21 trials with equal allocation (1:1:1) and 8 trials with unequal allocation. There was no significant difference in the proportion of trials with unequal allocation over the time period from 2010 to 2017. The categories of cancer which had the highest number of two arm clinical trials with unequal allotment were: genitourinary, breast and hematological malignancies (Table). Conclusions: Cancer clinical trials with unequal allocation between case and control arms have been common in the past decade. This may represent a new trend in clinical trial design to help enhance closer monitoring of adverse events despite higher costs attached to this method.[Table: see text]

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Response to letter: Wenle Zhao and Vance W. Berger, Better alternatives to permuted block randomization for clinical trials with unequal allocation

Hematology ◽

10.1080/10245332.2016.1232551 ◽

2016 ◽

Vol 22 (1) ◽

pp. 64-64

Author(s):

Will Meurer ◽

Jeffrey Glassberg ◽

Jason Connor

Keyword(s):

Clinical Trials ◽

Block Randomization ◽

Unequal Allocation

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Better alternatives to permuted block randomization for clinical trials with unequal allocation

Hematology ◽

10.1080/10245332.2016.1236996 ◽

2016 ◽

Vol 22 (1) ◽

pp. 61-63 ◽

Cited By ~ 4

Author(s):

Wenle Zhao ◽

Vance W. Berger

Keyword(s):

Clinical Trials ◽

Block Randomization ◽

Unequal Allocation

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Localization of Gallium-67 in Peritoneal Cells by Electron Microscopic Autoradiography

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100072460 ◽

1973 ◽

Vol 31 ◽

pp. 404-405

Author(s):

D. C. Swartzendruber ◽

Norma L. Idoyaga-Vargas

Keyword(s):

Clinical Trials ◽

Soft Tissue ◽

Tumor Tissue ◽

Soft Tissue Tumors ◽

Clinical Usefulness ◽

Electron Microscopic ◽

Normal Cells ◽

Electron Microscopic Autoradiography ◽

Peritoneal Cells ◽

Gallium 67

The radionuclide gallium-67 (67Ga) localizes preferentially but not specifically in many human and experimental soft-tissue tumors. Because of this localization, 67Ga is used in clinical trials to detect humar. cancers by external scintiscanning methods. However, the fact that 67Ga does not localize specifically in tumors requires for its eventual clinical usefulness a fuller understanding of the mechanisms that control its deposition in both malignant and normal cells. We have previously reported that 67Ga localizes in lysosomal-like bodies, notably, although not exclusively, in macrophages of the spocytaneous AKR thymoma. Further studies on the uptake of 67Ga by macrophages are needed to determine whether there are factors related to malignancy that might alter the localization of 67Ga in these cells and thus provide clues to discovering the mechanism of 67Ga localization in tumor tissue.

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