Biotech giant Vertex Pharmaceuticals (VRTX -0.06%) ended 2023 with an important regulatory approval. The company's gene-editing therapy for a duo of blood-related disorders, Casgevy, earned the nod in several countries. This development capped off another excellent year for the drugmaker, one during which -- as usual -- it crushed the market.

However, at least on the clinical front, Vertex isn't exactly starting 2024 with a bang. The company recently released positive but somewhat disappointing data from a phase 3 clinical trial for one of its otherwise promising drug candidates. Let's take a closer look at this news and what it means for investors.

Vertex's pain medicine (kind of) misses the mark

There is no shortage of medications for acute pain on the market, including some that can easily be acquired over the counter. Still, many of them, particularly those that contain opioids, come with severe potential side effects, not to mention the possibility of abuse. Vertex's goal is to develop pain meds that can be as effective as opioid-based ones but without similarly detrimental side effects.

In a phase 3 study for its top candidate in this area, VX-548, the biotech reported that the investigational medicine delivered positive results. That is, it was able to help patients with moderate or severe acute pain who had undergone abdominoplasty surgery (better known as a tummy tuck) or bunionectomy surgery (to remove foot bumps). But there's a catch.

Besides the placebo group, the study also compared VX-548 with a combination of hydrocodone bitartrate and acetaminophen (hydrocodone is an opioid). VX-548 did not perform nearly as well as the opioid pain treatment it was pitted against in managing acute pain in patients following bunionectomy surgery.

There are plenty more exciting candidates

What do these results mean for Vertex Pharmaceuticals? Although the company still plans on seeking approval for VX-548 in acute pain, it may no longer be the exciting opportunity the biotech thought it would be. However, that means very little for Vertex's future. Let's consider three reasons why.

First, Vertex's signature cystic fibrosis (CF) franchise continues to perform well. The drugmaker reported revenue of $7.4 billion through Sept. 30, equaling an 11% year-over-year increase. Vertex's net income grew by 6% to $2.7 billion. The company has yet to start treatment on about 20,000 patients (out of 92,000) eligible for its current CF medicines.

Second, Casgevy's recent approval is an important one. Although Vertex will have to share the profits and costs associated with Casgevy with CRISPR Therapeutics, its partner on this project, the therapy's potential is huge. It carries a price tag of $2.2 million and has an initial target market of about 35,000 patients.

Third, Vertex Pharmaceuticals has plenty of other exciting candidates. VX-548 is also being developed to treat neuropathic pain. The biotech has a CF medicine in the pipeline that is supposed to report data from late-stage studies this year, and that could be even more effective than its current drugs.

Vertex is also developing VX-864 and inaxaplin to treat alpha-1 antitrypsin deficiency and APOL1-mediated kidney disease, respectively. There are no treatments that address the underlying causes of either disease, and both have patient populations of about 100,000 people. That's how the company made a fortune in CF -- it created medicines that targeted the underlying causes of the disease when nobody else could.

Vertex's pipeline has other intriguing candidates, including one that could be a functional cure for type 1 diabetes. Since VX-548 was still effective at treating pain, it should earn regulatory approval. But the company could launch at least a couple more products in the next five years.

In short, the biotech's prospects remain bright despite VX-548's somewhat mixed results. Vertex Pharmaceuticals is still a top biotech stock to buy.