Can the spread of gene drive-modified mosquitoes be stopped once they have been released?

Yes, in theory. Self-limiting gene drive systems are designed specifically to disappear from the population after some period of time in the absence of repeated releases of the gene drive-modified mosquitoes. Self-sustaining gene drive-modified mosquitoes (mosquitoes that contain a heritable modification that is intended to become stably established within interbreeding populations) theoretically could be controlled or eliminated by any of several strategies following their release into the environment. Possible ways to eliminate gene drive modified-mosquitoes from the environment include the following:

• Using chemical insecticides
• Releasing large numbers of mosquitoes carrying natural or engineered DNA sequences that are resistant to the gene drive
• Disabling or removing the initial gene drive by releasing a second gene drive technology specifically designed to target and inactivate the first technology
• Using small molecules that specifically inhibit the gene editing enzyme Cas (if part of the gene drive system), thereby shutting off the gene drive

Some of these strategies have been tested in the laboratory or insectary, but they have not been tested in the field since no field testing of gene drive-modified mosquitoes has yet been conducted.
For more information:

https://www.who.int/publications/i/item/9789240025233
https://www.youtube.com/watch?v=s-dgdJQ_lO8&list=PLbopRNGowKJ8b1EJMAU53ZC46vgY4p2cz
https://www.annualreviews.org/doi/abs/10.1146/annurev-ento-020117-043154