When it comes to finding good pharma stocks to buy, I try to focus on companies that are developing drugs that can help huge numbers of people. After all, high profits are the ultimate key catalyst for stocks, and it’s much easier for companies to generate gigantic profits if there is a huge demand for the products they are developing.

The following three drug stocks certainly fit that criterion. One has a very promising treatment for cancer, which is a leading cause of death in both the U.S. and worldwide. The second pharma stock to buy that I’m presenting today has created a diabetes treatment that has a tremendous amount of potential. Diabetes is also a leading killer in America and worldwide, and its prevalence is soaring each year in America and globally.

The final company on my list has developed what appears to be a great, non-addictive treatment for pain. Of course, pain is a widespread condition that all humans experience and addictive pain treatments have killed millions of people over the past 20 years.

Here are the three excellent pharma stocks to buy for long-term investors.

Pharma Stocks: GSK (GSK)

I first became excited about GSK’s (NYSE:GSK) cancer treatment, Jemperli, after a study last year showed that the drug had completely cured 100% of the 12 patients who received a regimen of it. I never remembered seeing a cancer drug obtain a 100% cure rate in any trial.

In recent months, GSK has taken steps that are bringing Jemperli closer to becoming a blockbuster. Last month, for example, the FDA approved Jemprli as a treatment for certain types of endometrial cancer. Also, in February, an FDA panel recommended that GSK be allowed to use the “data from two proposed single-arm trials” on Jemperli to prove that the drug is an effective treatment for some types of rectal cancer.

By only presenting data on rectal cancer patients that receive Jemperli, without comparing their progress to patients that receive a placebo, GSK will be able to obtain FDA approval for the drug’s use as a treatment for the disease more quickly and more cheaply. Also noteworthy is that the agency has given Jemprli “fast track designation” in the rectal cancer indication, showing that the FDA is very optimistic about the drug and making it easier for the treatment to be approved much more quickly.

Over the long term, I expect Jemperli to be approved as a treatment for a wide array of cancers in Europe, India, Japan, and many other countries.

 VTv Therapeutics  (VTVT)

Like GSK, vTv (NASDAQ:VTVT) has a drug that looks poised to become a blockbuster, and the company continues to make progress on fulfilling the treatment’s huge potential.

Specifically, vTv earlier this month announced that it plans “to commence launch activities” for two studies of its diabetes drug, TTP399, later this year. Additionally, vTv noted that the FDA had approved the company’s blueprint for a trial of TTP399 in pediatric patients.

The FDA has given TTP399 “breakthrough” status, indicating that the agency is extremely enthusiastic and optimistic about the drug. The designation will also allow vTv to bring the drug to market more quickly.

In a Phase 2 trial, TTP399 meaningfully lowered Type 1 diabetes patients’ blood sugar levels and cut the number of their “hypoglycemic episodes by 40%.” The FDA has agreed to allow vTv to use the “number of hypoglycemic events” as the primary endpoint for the company’s two upcoming studies. Given the tremendous success of TTP399 in lowering such events in the previous, Phase 2 trial, I expect the drug to easily meet the primary goal in the two upcoming trials.

Although vTv is primarily developing TTP3999 as a treatment for Type 1 diabetes, in a previous trial, the drug “achieved statistically significant reductions in” the blood sugar levels of type 2 diabetes patients.

Consequently, I expect vTv to eventually develop the drug as a treatment for Type 2 diabetes.

Vertex Pharmaceuticals (VRTX)

Last October, Vertex Pharmaceuticals (NASDAQ:VRTX) launched a Phase 3 trial of its anti-pain drug, VX-548. In July, the company announced that it intended to launch a second Phase 3 trial last quarter.

Both studies will assess “the efficacy and safety of VX-548 for moderate to severe acute pain following bunionectomy or abdominoplasty surgery.”

In two Phase 2 trials, the drug triggered ” a rapid, statistically significant and clinically meaningful improvement” of pain levels, Vertex reported in March.

The drug was generally “well-tolerated.” And importantly, according to Vertex, the treatment does not have “addictive potential.” Moreover, Vertex noted that “the FDA has granted VX-548 Breakthrough Therapy Designation for the treatment of moderate-to-severe acute pain.”

As with vTv, the FDA’s decision to grant VX-548 Breakthrough designation shows that the agency is very upbeat about the drug’s potential, and the designation should allow Vertex to bring the drug to market relatively quickly and cheaply.

Given the huge potential of VX-548, the 20.8 forward price-earnings ratio of VRTX stock is quite attractive.

As of the date of publication, Larry Ramer owned shares of VTVT. The opinions expressed in this article are those of the writer, subject to the InvestorPlace.com Publishing Guidelines.