Designing gene drives to mitigate their unintended adverse risks and expand their potential benefits. All strategies have been tested experimentally but are still confined to laboratories and have not been established in the environment. A key challenge preventing the spread of gene drives and cutting back their benefits is the development of resistance. So far, three strategies have been published and shown a positive impact on reducing resistance allele formation in gene drives: (a) the multiplex gRNA expressing system [74
], (b) the use of the nanos promoter for Cas9 expression [75
], and (c) the combination of different gene drives (e.g., homing endonuclease drive with cleave and rescue drive), showing a significant potential to overcome the accumulation of drive-resistant alleles [77
]. On the contrary, several containment strategies have been successfully proposed and established to mitigate the unintended negative impacts of gene drives on the environment. Among the molecular approaches: (a) a threshold-dependent gene drive [47
], (b) a safeguarding gene drive, and (c) a reverse gene drive, were first designed and tested in S. cerevisiae
]. (d) The use of genetic neutralizing elements [88
] and (e) anti-Crispr protein [89
] was also two novel containment measures in gene drive research.