MannKind said today its founder and executive chairman Alfred Mann has returned to the company’s day-to-day helm as interim CEO following the resignation of Hakan Edstrom as president, CEO and director.

The temporary succession, which took effect yesterday, caps a troubled few months for the developer of Afrezza, an inhaled form of insulin that is co-marketed with Sanofi under an up-to-$925 million worldwide exclusive licensing agreement.

Sales of Afrezza have failed to match expectations, generating just €5 million ($5.3 million) in net sales during the first nine months of this year, of which €2 million ($2.1 million) came during Q3. Back in 2013, Piper Jaffray analyst Ian Somaiya had projected that Afrezza would rack up more than $2 billion in peak annual sales in U.S. and Europe.

The weaker-than-projected sales have touched off three rounds of layoffs at MannKind this year, in which an undisclosed number of employees have been idled. The latest layoff round was confirmed by the company in September.

Before that, MannKind had spoken publicly about expansion plans. In August, the company told investors it was working to develop products in two treatment areas besides diabetes, pain management and pulmonary hypertension.

And in April, the company disclosed it was tripling its production capacity at its manufacturing site in Danbury, CT, where the company is headquartered, from one manufacturing line capable of producing up to 120 million cartridges of Afrezza annually, to three lines with a combined annual capability of 360 million cartridges. The two new lines were successfully validated in July.

MannKind had hoped to sell up to 50 million shares on the Tel Aviv Stock Exchange that was expected to raise $120 million. Instead, the company was only able sell 13,852,435 shares, generating $36.2 million before deducting placement agent fees, escrow agent fees and other estimated offering expenses.

Sanofi has sought to rebuild a diabetes franchise weakened earlier this year by the end of U.S. patent protection for longtime but declining blockbuster Lantus.

Earlier this month, Sanofi scrambled to strengthen its pipeline in diabetes by announcing a collaboration with Hanmi of up to €3.9 billion (about $4.2 billion) to develop long-acting diabetes treatments, followed by a partnership with Lexicon Pharmaceuticals of up to $1.7 billion to develop and commercialize the Phase III candidate sotagliflozin (LX4211).