In an extraordinary signal of the progress that is being made to find treatments for some types of rare disorders, an advisory committee to the U.S. Food and Drug Administration (FDA) has recommended approval this week for not just one but two new drugs to treat homozygous familial hypercholesterolemia (HoFH).

The two drugs — mipomersen and lomitapide — both offer the ability to lower low density lipoprotein (LDL) levels — so-called “bad” cholesterol levels – in patients with an inherited form of hypercholesterolemia that is believed to affect about 1 child in every million births. Traditional forms of cholesterol-lowering agents like statins often have little to no impact on cholesterol levels in patients of this type. Indeed, patients with HoFH are at risk for serious cardiovascular disease in childhood and, historically, it has been unusual for such patients to survive into their 30s.

In homozygous familial hypercholesterolemia, both copies of selected genes (e.g., genes coding for the LDL receptor or for apoprotein B) are mutated, and so patients with such homozygous mutations are effectively unable to break down low density lipoproteins, which therefore accumulate in the body at extremely high levels. A less aggressive (and much more common) form of familial hypercholesterolemia — heterozygous familial hypercholesterolemia or HeFH — occurs when only one of the two genes is mutated and so patients are simply less efficient than normal at breaking down LDL.

Whether the FDA will actually approve either or both of these products is still unknown at this time. The advisory committee appears to have given a strong (13 to 2) vote in favor of approval of lomitapide but a less enthusiastic endorsement (9 to 6) in favor of mipomersen. Both drugs have indicated significant risk for side effects in some patients, and the FDA will need to come to its own conclusions about the risk-benefit ratios for each product. There are also concerns about risks associated with the potential for use of these drugs in patients who have the less aggressive, heterozygous form of the disease.

What I find important here, however, is that we have reached a time when we can see two products recommended for approval for any single rare disorder in the very same week. The challenges in developing therapies for any rare disorder are considerable, but clearly our technical abilities to take on these challenges are growing, and regulators are demonstrating a willingness to accept and assess data based on well-designed trials in small numbers of patients in order to address such unmet medical needs. Do we need to exert appropriate caution in the clinical use of these particular products to minimize risks to patients with less severe forms of FH? Certainly we do. On the other hand, by sometime early next year it is at least possible that patients with HoFH and their physicians may have two new opportunities to manage some of the consequences of a rare, hereditary disorder … and those patients may to be able to live longer, higher quality, and more productive lives as a consequence.