What happened

Shares of CRISPR Therapeutics (CRSP 1.92%) jumped 13.8% in June, according to data provided by S&P Global Market Intelligence, after the biotech released data at two different medical meetings during the month.

So what

First, CRISPR and its partner Vertex Pharmaceuticals (VRTX -0.69%) presented additional data from its clinical trials testing their gene-editing therapy CTX001 in patients with transfusion-dependent beta thalassemia (TDT) and severe sickle cell disease.

Both patients with TDT haven't required transfusions since they received their therapies five and 15 months ago. That's pretty impressive, considering they previously required 61 units and 34 units of red blood cells per year, respectively, in the two years before treatment.

Nine months after the treatment, the patient with sickle cell disease continues to express fetal hemoglobin, the gene put into the patient via CRISPR-Cas9. The patient remains free of vaso-occlusive crises (VOCs), the painful attacks caused by sickled red blood cells clogging small blood vessels. In the two years prior to treatment, the patient experienced an average of seven VOCs per year.

Doctor talking to a patient

Image source: Getty Images.

Later in June, CRISPR Therapeutics presented data on its CAR-T cell cancer treatment at the American Association for Cancer Research Virtual Meeting II. CRISPR's technology can generate off-the-shelf CAR-T cells made from donor cells rather than needing to be manufactured specifically for each patient like first-generation CAR-T therapies.

Now what

CRISPR Therapeutics is off to a good start in both hematologic diseases and cancer treatments, but investors should keep in mind that the therapies are still early in the clinical-trial marathon, and a lot can happen to derail the treatments before they reach the market.

Given the risks, investors would be wise to keep CRISPR Therapeutics (and any other early-stage biotech) as a small fraction of their overall portfolio.