My first comment was going to be that “symptomatically treating” is a thing as in, it doesn’t directly shrink, damage, or otherwise affect the tumor in any way, it just reduces the amount that the tumor affects the person’s mood and cognition. Kinda like cold medicine doesn’t actually do anything to the viruses, it just unclogs your sinuses and stops your nose from itching and running which makes you more comfortable and helps you rest better which can kind of indirectly help the rest of your immune system handle things.

But more directly in response to this comment, there is good odds they’ll create a specific formulation that’s officially approved for the treatment of brain tumors. A great example of a medication that this currently applies to is Zyban, which is one of two Brands of the generic drug bupropion, the another common one being Wellbutrin. Zyban is specifically approved for the treatment of nicotine addiction, while wellbutrin is only prescribed “off label” for that specific purpose which means the doctor is giving it out of their own judgement (because they’re literally the exact same chemical: bupropion).

Now, there are some ways that different brands might actually be better or worse for certain things for instance the specific dosage could be different in a way that would be harder to achieve otherwise; it’s easier to tell a patient to take 1 tablet daily or twice a day than having to explain to them how to cut the tablet then take 1.5, or to measure out a syrup. More importantly though, the same drug can be given in forms that effect how quickly they’re released into the body, think advil quick release vs motrin, which are both ibuprofen. With psychiatric drugs like bupropion (which is also given for depression and ADHD) you more often see extended release, so that the effects are more long-lasting throughout the day.

All that said, while I couldn’t find a side-by-side dose comparison, that’s the lesser difference considering effective dosage is going to be a more variable efficacy factor between individual patients. Both come in extended release formulations meaning Zyban has no real reason to be around twice as expensive as Wellbutrin.