Buying speculative healthcare stocks during an almost decade-long bull market might sound like a shaky proposition. But this is no ordinary bull market. The global push to legalize marijuana, combined with the advent of game-changing new medical treatments, has provided a sound basis for the sector's steady rise northward. Even so, the best may be yet to come. 

The biotech CRISPR Therapeutics (CRSP 9.21%) and cannabis giant Curaleaf Holdings (CURLF 3.46%) are two names experiencing a rapid upward trajectory in 2019. Despite their enormous gains so far this year, these two red-hot growth stocks appear to have a lot more room to run based on their long-term prospects. In fact, I'm considering adding both of these stocks to my portfolio right now. Here's why. 

A pair of hands trimming dried marijuana flowers.

Image source: Getty Images.

A top gene-editing play

Biotechnology has already transformed the treatment paradigm for scores of hard-to-treat diseases. But the novel gene-editing platform known as CRISPR/Cas9 could push this effort into hyperdrive. Right now, CRISPR and partner Vertex Pharmaceuticals (VRTX -0.38%) are trialing the first company sponsored CRISPR/Cas-9-based therapy, CTX001, in patients with beta thalassemia and sickle cell disease. Earlier this year, the Food and Drug Administration granted CTX001 Fast Track designation for both of these rare blood disorders. 

While these trials are in their early stages, it is interesting to note that Vertex did decide to go ahead and expand this collaboration to include the muscle disorders known as Duchenne muscular dystrophy and myotonic dystrophy type 1 last month. In doing so, Vertex reportedly doled out a hefty $175 million up-front cash payment to CRISPR. That's a huge vote of confidence in CRISPR's intriguing, yet still unproven, platform. 

Apart from its partnership with Vertex, CRISPR is also close to initiating an early-stage trial for its so-called off-the-shelf T cell therapy CTX110 targeting CD19 positive malignancies. If successful, CTX110 could unlock the tremendous promise of adoptive cell therapies, which are currently hampered by deadly side effects and various logistical issues.  

CRISPR also has an unusually strong balance sheet for a clinical-stage biotech. After this latest cash infusion from Vertex, CRISPR should have a comfortable cash runway of no less than 24 months from here on out and perhaps even longer depending how costly these additional trials turn out to be. 

What's the bottom line? Even though CRISPR's shares have appreciated by a staggering 72% so far this year, there's no reason to think that its shares are going to cool off anytime soon -- that is, barring a clinical setback. The biotech's therapeutic platform, after all, could be worth tens of billions in future sales. And that's the main reason why I'm strongly considering adding this development biotech stock to my portfolio soon. 

More consolidation, more growth

American cannabis dispensary giant Curaleaf Holdings has seen its shares rise by an astounding 61% this year and for good reason. In the most recent quarter, the company reported a noteworthy 288% bump in revenue compared to the same period a year ago, thanks to its aggressive acquisition strategy that pulled in names like Eureka Investment Partners, Acres Cannabis, Cura Partners, among others. 

Yesterday, the company cemented its place at the top of the U.S. dispensary totem pole by acquiring GR Companies for $875 million in cash and stock. This latest transaction expands Curaleaf's footprint into a healthy 19 states, up from 12 prior to this deal. Curaleaf also noted that this acquisition makes it the largest cannabis in the world by revenue. In short, Curaleaf is a force to be reckoned with GR Companies now in the fold.

As an important aside, Curaleaf also seems to be in the catbird position to attract a deep-pocketed partner looking for an entry point into the all-important U.S. cannabis market. Such a deal would likely drive even further share-price appreciation and perhaps lead to a lucrative buyout deal, once the U.S. effectively ends federal prohibition.

So, while this pot stock still qualifies as speculative in nature, I'm definitely mulling over the idea of playing the long game with this top U.S. dispensary stock. Eventually, the legal barriers in the U.S. will fall and Curaleaf should benefit enormously from this seminal event, especially after yesterday's game-changing deal with GR Companies.