Clarifying the Ethics and Oversight of Chimeric Research.

This article is the lead piece in a special report that presents the results of a bioethical investigation into chimeric research, which involves the insertion of human cells into nonhuman animals and nonhuman animal embryos, including into their brains. Rapid scientific developments in this field may advance knowledge and could lead to new therapies for humans. They also reveal the conceptual, ethical, and procedural limitations of existing ethics guidance for human-nonhuman chimeric research.

Should Participants in Clinical Trials Be Able to Withdraw from Passive Follow-Up?

A research participant's right to withdraw from all research procedures is widely accepted, but there can be justifiable limits to a participant's exercise of autonomy to withdraw from some procedures. Clinical outcomes trials depend on complete subject follow-up for accurate assessment of the safety and efficacy of investigational therapies. Subjects' refusal to complete follow-up, even through passive medical record review, can cause failure to detect safety signals, inaccurate estimation of efficacy, or lack of acceptance of trial results, which alters the study's benefit-risk ratio.