Seattle Genetics' (NASDAQ:SGEN) shares soared as much as 6% after the U.S. Food and Drug Administration approved its bladder cancer drug this month, and the stock now is heading for a total gain of more than 86% for 2019. The biotech company, which has a pipeline of candidate treatments for various cancers, now has a new product on the market and is optimistic about an investigational treatment that recently earned the FDA's "breakthrough" label.

Researcher looks into a microscope.

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Let's have a closer look at the two elements that could lift the shares in 2020, even after this year's spectacular performance.

1. FDA approval of Padcev

Seattle Genetics announced the accelerated approval of Padcev (generic name: enfortumab vedotin-ejfv) on Dec. 18 for the treatment of patients with locally advanced or metastatic urothelial cancer. It's the most common kind of bladder cancer, and develops in the cells lining the inside of the bladder. The approval is specifically for adult patients who have previously been treated with platinum-based chemotherapy and a PD-1 or PD-L1 inhibitor. PD-1 and PD-L1 are proteins in the body, and in some cases, they help cancer cells hide from an immune system attack. Inhibitors prevent this from happening. As for Padcev, it targets the Nectin-4 protein and leads to the destruction of cancer cells.

A key point in this approval news is that Padcev is the only FDA-approved drug for this patient set, meaning that it will be an obvious choice and welcome option for many. Seattle Genetics has said about 2,000 to 4,000 new patients per year may be candidates for Padcev, but CEO Clay Siegall said it's difficult to forecast an exact patient population. However, according to Grand View Research, the global urothelial cancer drug market will reach $3.6 billion by 2023, with a compound annual growth rate of 23%. In the U.S., about 80,000 new cases of bladder cancer are diagnosed per year, and about 90% of cases are of the urothelial type. So a foothold in this market is a definite growth opportunity for Seattle Genetics.

2. A breakthrough drug on the horizon

Seattle Genetics aims to submit tucatinib, its investigational treatment for HER2-positive breast cancer, to the FDA in the first quarter. That's a positive development, but even better is the fact that the FDA already granted tucatinib breakthrough status based on data from a phase 3 clinical trial. Tucatinib was administered along with Roche's Herceptin and another drug, and risk of death declined by 34%. The study also showed a 46% decline in risk of disease progression. HER2 stands for a protein -- human epidermal growth factor receptor 2. In HER2-positive breast cancer, high levels of this protein within tumors lead to the spread of cancer cells. Tucatinib inhibits enzymes that activate this type of protein.

Breakthrough status is meant to expedite review and approval for treatments that address life-threatening illnesses, so if all goes well, Seattle Genetics could have a third drug on the market sooner rather than later. (The company also sells Adcetris for Hodgkin lymphoma.) The market for HER2-positive breast cancer is expected to increase by 54% from its 2015 level to $9.89 billion in 2025, according to GlobalData.

Padcev and tucatinib both address conditions where the need for new treatments is obvious. Though Seattle Genetics' earnings history hasn't been great -- it missed its EPS forecasts in the past two quarters -- its recent product news offers investors reasons for optimism about revenue streams to come. A new drug on the market and high hopes for another approval are catalysts that should help its share price make healthy gains in the new year.