There's never been a good time to have a rare blood-based disorder, but there's also never been a better time than right now. That's because the U.S. Food and Drug Administration (FDA) has been unusually quick to review and approve new drug applications for treatments with life-saving potential for small groups of patients.

In the fourth quarter alone, the FDA approved three new drugs for people who inherited life-threatening blood disorders, months ahead of schedule. Here's why they could also become some of the most successful new drug launches of 2020.

New Drug (Generic Name) Indication Company (Symbol)
Oxbryta (voxelotor) Sickle cell disease (SCD) Global Blood Therapeutics (NASDAQ:GBT)
Adakveo (crizanlizumab-tmca) SCD-related Vaso-occlusive crisis  Novartis (NYSE:NVS)
Givlaari (givosiran) Acute hepatic porphyria Alnylam (NASDAQ:ALNY)

Data source: U.S. Food and Drug Administration.

Why speedy reviews matter

So much work goes into assembling new drug applications that drugmakers needed more than one delivery vehicle to deliver the mountains of paper they were printed on. Electronic filing has reduced the amount of paper required, but the FDA still takes 10 months to review a standard application, or six months for a priority review.

Once in a while, the FDA finds a candidate's potential benefits so compelling that a six-month priority review is reduced to just three or four months. The agency doesn't care about corporate profits any more than patients do, but new drugs that receive speedy approvals usually have characteristics that help them outperform in the commercial stage.

Three healthcare professionals giving a thumbs up.

Image source: Getty Images.

1. Oxbryta from Global Blood Therapeutics

Hemoglobin's the protein in red blood cells that cart oxygen from the lungs to tissues that need it. Patients with SCD inherited a mutation that causes hemoglobin molecules to adhere to each other, which limits their function and distorts the shape of red blood cells. 

The first drug from Global Blood Therapeutics, Oxbryta, prevents hemoglobin from sticking together and causing red blood cells to take on a sickle shape. During the pivotal study that convinced the FDA to approve Oxbryta, 51% of patients who received the drug showed increased concentrations of functional hemoglobin, compared to just 7% of the placebo group.

There are around 100,000 people with SCD in the U.S. and millions more around the globe who rely on costly blood transfusions to replace sickled blood cells with new ones. As the first treatment to address the root cause of SCD, Oxbryta could produce billions in annual top-line revenue for Global Blood Therapeutics, while saving end payers a bundle.

2. Adakveo from Novartis

Sickle-shaped red blood cells aren't just bad at carrying oxygen -- they also get stuck in small blood vessels. As a result, many SCD patients suffer from painful bouts of vaso-occlusive crises (VOC), which can lead to permanent organ damage.

Adakveo's an injectable treatment that prevents red blood cells from sticking together in order to limit blood vessel blockages. During pivotal studies leading to its approval, the new drug from Novartis lowered the median rate of VOC-related hospitalizations by 45%, compared to a placebo.

Not all, but many, SCD patients spend a significant portion of their lives in the hospital -- which isn't cheap. That means end payers eager to reduce their expenses will appreciate Adakveo almost as much as the patients who receive it.

FDA approved stamp.

Image source: Getty Images.

3. Givlaari from Alnylam

This drug's aimed at another life-threatening blood disorder called acute hepatic porphyria (AHP). The disease's root cause is an inherited mutation that leads to the overproduction of oxygen-carrying portions of hemoglobin known as porphyrin.

Unbound porphyrin is neurotoxic, and before Givlaari's approval, there weren't any treatments that prevented its buildup or the severe pain and seizures patients experience during porphyria attacks. This rare disease drug from Alnylam interferes with porphyrin production and reduced the number of porphyria attacks by 70% during the study that led to its approval.

Alnylam set a list price of $575,000 for a one year supply of Givlaari, which isn't unusual for drugs with very small patient populations. The exact number of patients affected by AHP is still a mystery, but the availability of a viable treatment option tends to bring patients with rare diseases out of the woodwork. If the AHP population turns out to be larger than expected, Givlaari could become the most successful drug on this list.

Looking ahead

New drug launches are even more unpredictable than clinical trial results, but it's not that hard to guess which one of these stocks has the most to lose from an unsuccessful launch of a drug on this list. Oxbryta is the only product Global Blood Therapeutics has to sell at the moment, which means its $5 billion market cap could collapse if sales don't take off during the next several quarters.

Over the past year, revenue at Novartis climbed to $54.9 billion, so Adaveko isn't going to move the stock very far in one direction or another. Givlaari is Alnylam's third new drug to earn approval, and its first, Onpattro, hit pharmacy shelves a little over a year ago. If you're thinking about adding one of these stocks to your portfolio, Alnylam's probably the best bet at the moment.