Generally it is not the big pharma companies (although they are an inviting target) that withhold treatments that hold promise. If there was any way in the world they could make a buck off of any treatment, they would. The thing that stops them is usually the government (the FDA in the United States). The US has one of the more restrictive drug policies on the planet, and as a result, many promising treatments practiced elsewhere are not done here as they were deemed either too dangerous or not giving any appreciable benefit to patients.
The easiest way to get around this block then is to engage in "medical tourism," traveling abroad to receive treatment not approved or overly expensive in one's own home country.