What's happening: ImmunoGen (IMGN) hosted an investor presentation this morning that led to the company's shares falling over 10% earlier today.

Why it's happening: Since today's drop merely erases gains notched yesterday ahead of the conference, investors should probably keep ImmunoGen's drop in context -- especially since ImmunoGen has been one biotech's best performers this year, with shares rallying nearly 200% year to date.

Regardless, after reviewing ImmunoGen's investor presentation, it doesn't appear to contain any worrisome or overly unexpected revelations. The company's update includes plans to advance its ovarian cancer drug IMGN853 into two phase 2 trials, one of which it thinks could provide for an accelerated approval pathway. Specifically, the company's Forward 1 study will contain two stages and will evaluate IMGN853 as a monotherapy in pre-treated ovarian cancers with an amenable genetic makeup.

The first stage will explore dosing options, including a once-every-four-weeks regimen that may improve the drug's safety profile, and determine the best patient population to target. The second stage will compare IMGN853 to the current standard of care, the findings from which could support a meeting with the FDA regarding the coveted accelerated pathway. A second phase 2 study, Forward 2, will also be launched that will evaluate IMGN853 as part of a combination therapy with existing treatments in patients at an earlier stage of their disease.

Both trials are expected to begin before the end of this year, and full data supporting a regulatory meeting could be available at some point in the first half of 2016.

ImmunoGen also spent time updating investors on its other programs, including IMGN529 and coltuximab ravtansine, two therapies targeting B-cell cancers. ImmunoGen plans include a phase 2 combination study of IMGN529 and Rituxan in patients with recurrent or relapsing non-Hodgkins lymphoma, including those with DLBCL, and a phase 2 study of coltuximab ravtansine in combination with other agents, to begin next year.

The company also reminded investors that its collaborators, which already have 8 clinical stage compounds, should add another 2 compounds to the clinic in 2016, and that its balance sheet still includes $278 million in cash, thanks in part to the sale of its Kadcyla royalty rights earlier this year.

Regardless, investors' negative reaction to ImmunoGen's presentation could be attributed to all the planned activity, which may quicken the pace at which ImmunoGen's cash stockpile disappears, or to the focus on combination therapy, rather than monotherapy, for its B-cell drugs.

Overall, it seems to me that neither of those reasons, nor anything else in ImmunoGen's presentation, is cause for a prolonged sell-off, and if I'm correct, then this drop may prove to be a good opportunity to add shares to portfolios.