What happened

Shares of cancer specialist Immunomedics (NASDAQ:IMMU) rose by an astounding 106.4% in pre-market trading Monday morning. The biotech's shares are ripping higher this morning in response to a $21 billion buyout agreement with industry giant Gilead Sciences (NASDAQ:GILD).

Gilead reportedly agreed to pay $88 per share to acquire Immunomedics in an all-cash transaction, which equates to a 108% premium relative to where the drugmaker's shares closed last Friday. The deal is expected to close in the fourth quarter of 2020, according to the press release. 

Wooden blocks that spell buy-out.

Image source: Getty Images.

So what

The impetus behind Gilead's latest acquisition is Immunomedic's FDA-approved metastatic triple-negative breast cancer (TNBC) drug, Trodelvy. Trodelvy, a cancer-fighting therapy known as an antibody-drug conjugate, is expected to generate approximately $2.3 billion in sales for its initial indication by the middle of the decade.

However, Wall Street thinks the drug's peak sales could eventually top $6 billion if Gilead can successfully tack on other high-value indications to its label down the road. In short, Gilead may be paying as little as 3.5 times Trodelvy's peak sales to acquire Immunomedics, which is a fairly reasonable price tag for a top oncology asset. 

Now what

Following this high-dollar oncology acquisition, Gilead probably won't be striking any more major buyout deals any time soon. After all, the blue-chip biotech has already spent a whopping $25.9 billion this year to bolster its cancer portfolio -- through this $21 billion transaction, along with a $4.9 billion deal for the CD47 drugmaker Forty Seven in March. The main thrust of Gilead's long-awaited pivot to oncology therefore appears to be more or less complete at this point.