What happened

Shares of Array BioPharma (ARRY), a commercial-stage biopharmaceutical company developing highly targeted cancer therapies, soared 75.4% higher in the first half of 2019, according to data from S&P Global Market Intelligence. A string of recent successes that finished with a juicy buyout offer from Pfizer (PFE -0.68%) in the middle of the month sent the stock soaring.

So what 

When Swiss pharma giant Novartis (NVS -0.23%) returned the cancer drug candidates Braftovi and Mektovi that it had previously licensed from Array in 2015, targeted small-molecule cancer drugs weren't nearly as popular as they are now. One reason had to do with a relative lack of tumor genome profiling that has improved a great deal and is still accelerating.

Prescription tablets stacked in shape of an upward-sloping bar chart.

Image source: Getty Images.

Sales of Braftovi and Mektovi for the treatment of melanoma patients with a BRAF mutation haven't been thrilling, but they're about to take off. Pfizer's sales force will also have a chance to market Braftovi plus Mektovi for the treatment of colorectal cancer (CRC) patients who have relapsed after previous treatment and have tumors that harbor a BRAF mutation.

Adding Braftovi and Mektovi to Erbitux reduced patients' risk of death by 48% compared to the group treated with Erbitux, a standard treatment, on its own. An application based on these results will head to the FDA before the end of the year, and approval could add more than $1 billion annually to Pfizer's top line by 2024.

Now what

Pfizer will shell out around $11.4 billion for Array, which works out to approximately $48 per share. That means buying up the stock now could squeak out a gain of around 3.6% before the year's finished if the acquisition completes as planned.

While it's too late to seek significant gains from this stock, there's an important lesson to be learned here. Cancer therapies that target specific mutations known to promote tumor growth are all the rage right now. While complex cellular therapies may receive the most attention from finance-related media, genetically tailored treatments that a patient can take home in a pill bottle are drawing the eyes of well-heeled pharmaceutical giants eager to expand their late-stage pipelines.