What happened

Shares of Momenta Pharmaceuticals, Inc. (NASDAQ:MNTA), a biopharmaceutical company specializing in "complex" drugs to treat immune-mediated disorders, sank as far as 10.3% in early-morning trading as investors who were asleep at the wheel last Friday took some profits off the table. The stock was still off by 10.1% as of 1:23 p.m. EST on Monday. 

So what 

On Friday, Momenta Pharmaceuticals announced data from an early-stage trial with the most advanced novel new drug candidate in the company's development pipeline. M281 is a protein engineered to reduce troublesome immunoglobulin G (IgG) antibodies that play a role in a range of immune-mediated disorders.

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Image source: Getty Images.

Top-line results from the 34-patient study suggest M281 is well-tolerated and capable of reducing the level of circulating IgG antibodies by around 80%, at least among the healthy volunteers who participated in the study. Some of the world's most successful drugs treat chronic immune-mediated conditions, but Momenta's market cap swelled by around $220 million on Friday.

If the results were proof M281 effectively treated a specific disease, Friday's run-up would be warranted. Simply proving M281 reduces circulating IgG within a group of 34 healthy volunteers is a step in the right direction, but hardly sufficient.

Now what

While it's encouraging to see Momenta develop its own drugs, investors will want to keep their eyes on sales of Glatopa. Marketed in partnership with Novartis (NYSE:NVS), the generic version of multiple sclerosis blockbuster Copaxone generated $10.9 million in product revenue recorded during the third quarter. Those sales are coming under pressure now that Mylan is marketing a longer-lasting version.

Cory Renauer has no position in any of the stocks mentioned. The Motley Fool recommends Momenta Pharmaceuticals and Mylan. The Motley Fool has a disclosure policy.