Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of MannKind Corp. (NASDAQ:56400P706) jumped by 10% this morning on heavy volume, continuing the stock's incredibly strong run of late. Specifically, the biotech's shares have risen nearly 30% in the past week alone:

MNKD Price Chart

While it's hard to point to a single catalyst behind this massive move upwards, investors appear to be encouraged by a couple of developments regarding the company's newly-launched inhaled insulin product Afrezza.

Source: MannKind

First off, MannKind and its marketing partner Sanofi (NASDAQ:SNY) are launching a print advertising campaign in the third-quarter to increase awareness about Afrezza among diabetics, presumably with the goal of increasing demand at the patient level. 

The second leg of good news is that the early reviews of Afrezza among users, and even some doctors, have been excellent. 

So what: Afrezza's commercial launch has gotten off to a rocky start, generating only $1.1 million in sales during its first two months on the market. According to a report from the Los Angeles Times, Afrezza's early commercial weakness has stemmed, in part, from the FDA's requirement that patients take a lung function test before they can receive the drug. In short, some doctors apparently aren't enthusiastic about having to meet this extra requirement in their already busy practices. MannKind and Sanofi are therefore hoping to overcome this hurdle by having patients request the drug. 

Now what: Inhaled insulin may indeed turn out to be a game-changer for diabetics. Even so, this huge upswing in MannKind's share price puts the company's market cap at nearly $3 billion, meaning that Afrezza's sales are going to have to pick up in unprecedented fashion to justify such a lofty valuation. As a result, investors with an eye on the long-term may want to stick to the sidelines with this volatile biotech -- at least until Afrezza is showing clear signs of living up to its blockbuster potential.