Predicting a buyout in the biotech sector is no easy business. The sheer number of collaborative possibilities and, in many cases, cross-company collaborations, makes predicting a buyout incredibly difficult -- if not downright impossible.

Sometimes, we as investors luck out and a buyout simply makes sense, such as the $958 million buyout of MAP Pharmaceuticals (NASDAQ: MAPP) by Allergan this week. MAP's lead product, Levadex, an inhaled migraine medication, has been licensed to Allergan in the U.S., and -- barring it took the corrective measures to fix the manufacturing issues that spoiled its initial attempt to get Levadex approved -- it should easily gain approval from the FDA come March 26, its PDUFA date.

Very few of these somewhat obvious buyouts present themselves until after the fact, but I believe I've honed in on three other biotech buyouts that would seem to make sense. As always, keep in mind that these are merely my best guesses and shouldn't be construed as anything more than that -- a guess!

Theravance (NASDAQ: THRX)
Personally, I'd call a hookup between Theravance and GlaxoSmithKline a no-brainer. Theravance and Glaxo have been like peanut butter and jelly when it comes to developing revolutionary new COPD treatments that combine Theravance's long-acting beta-2 agonists, or LABAs, with Glaxo's long-acting muscarinic antagonists, or LAMAs. Two of these LAMA/LABA combos have already been submitted to the FDA: Relvar or Breo for the treatment of COPD and asthma, and Anoro, which I touted in December as one of the biggest life-changing drug hopefuls of 2013. There are also two additional studies currently in early-stage trials.

An even better reason for Glaxo to snatch up Theravance is because it ended its partnership with Astellas Pharma with regard to skin infection drug Vibativ last year. Although Vibativ failed to gain a first-line recommendation from the FDA panel for the treatment of nosocomial pneumonia by a vote of 9-6 in late November, it did get a vote to recommend by a tally of 13-2 when other forms of treatment have been exhausted. With Astellas gone, Glaxo has no excess baggage to worry about and can claim Theravance's advancing pipeline all to itself.

No, I'm not joking around – VIVUS needs a partner for Qsymia and plenty of big pharmaceuticals need a potential blockbuster to add to the pipeline. You might be thinking that Bristol-Myers Squibb or AstraZeneca would be smart buyers of VIVUS here given their expected losses because of patent expirations, but the two have already collaborated on, and gained approval in Europe for, an SGLT-2 inhibitor known as Forxiga. Forxiga isn't designed indicated for weight loss, but it's nonetheless been a pleasant side effect for takers of the drug. 

Actually, Eli Lilly (NYSE:LLY) appears to be the most suitable candidate to snatch up VIVUS. Without a large presence in chronic weight management, yet maintaining a big presence in the diabetes market with its multiple insulin medications (Humalog, Humulin, and Glucagon), Lilly could actually pick up VIVUS on the cheap and add to its already impressive product portfolio. More importantly, Humalog, a $2.5 billion drug, is set to lose patent protection in May, making it even more imperative that Lilly find new sources of growth. Lilly's marketing team would be invaluable to marketing Qsymia, and Qsymia would give Lilly a drug capable of perhaps $350 million in sales by 2014.

Keep in mind, though, that without a partner I don't see VIVUS' shares heading much higher, so I wouldn't look for a huge premium if a buyout does occur because, in a way, it'd be a buyout on weakness.

The allure of ImmunoGen is that it offers one of the most unique biotech technologies within cancer research. Its TAP, or target antibody payload, technology allows a chemotherapy toxin to be attached to an antibody and be released only when it comes into contact with a specific signature protein found in a targeted cancer cell. The result is a significantly more potent dose of chemotherapy toxin to targeted cancer cells and less healthy tissue death.

Currently, ImmunoGen's lead drug in trials is T-DM1, an HER2-positive breast cancer treatment developed with Roche that's been submitted to the FDA for priority review. In trials, T-DM1 reduced the risk of death by 32% and extended overall median survival time to 30.9 months over the current standard treatment of Glaxo's Tykerb and Roche's Xeloda which produced a median survival time 25.1 months. In addition to this study, ImmunoGen has three wholly owned compounds in trials, as well as multiple other trials under way with Roche, Sanofi, Biotest, Amgen, and Bayer.

With Roche's T-DM1 being the furthest along in trials, it'd make the most logical buyer if the drug gains FDA approval -- and let me tell you, if T-DM1 is approved and Roche doesn't purchase ImmunoGen within a few months, we could be looking back in 10 years at one of the biggest "could of, would of, should of's" of all-time! The fact that ImmunoGen has so many collaborative partnerships could be a minor stumbling block, but I doubt it'd throw the possibility of a deal out the window. Sanofi could also make a case for purchasing ImmunoGen with three compounds currently in various early and mid-stage trials, but I stand by my assessment that Roche makes the most sense as a potential suitor.

Which biotech is next?
Which biotech company do you see on the block next? Sound off in the comment section below and share your ideas with the community.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.