Sanofi in April will stop marketing Afrezza, MannKind’s inhaled insulin, citing the low number of prescriptions even though the drugmaker made what it described as a “substantial” investment in sales and marketing, including the launch of the “Surprise, it’s insulin” campaign in mid-2015.

Sanofi spent $3.75 million on advertising for Afrezza during the third quarter of 2015 yet the therapy only brought in about $2 million in revenue for the drugmaker during that period, according to data from Kantar Media and Sanofi’s securities filings.

Afrezza has generated about $5.4 million in total sales since its launch in February.

“The decision to terminate is due to a number of factors, including the continued low level of prescriptions for Afrezza in the marketplace despite Sanofi’s substantial efforts,” a Sanofi spokesperson said in a statement.

During an investor call Tuesday afternoon, MannKind CFO Matthew Pfeffer said the company would seek a new marketing or licensing partner that is willing to engage in a new pricing strategy as well as focus future marketing efforts on educating physicians and patients about Afrezza’s “value proposition.”

“This is not the end of the line for Afrezza,” he said.

The drugmaker had struggled to find a commercialization partner, announcing in August 2014 that Sanofi would develop and commercialize Afrezza. The drug received FDA approval in June of that year. 

Afrezza, which is taken during meals, is the only FDA-approved inhaled insulin. Sanofi and MannKind promoted the treatment as an alternative for patients who dislike using needles or pens to inject insulin. But, like the other previous inhaled insulin product, Afrezza struggled to gain market share. Pfizer notably pulled its inhaled insulin therapy, Exubera, from the market in 2007 due to low sales.

Still, Afrezza’s prescriptions were expected to rise once Sanofi moved forward with its direct-to-consumer campaign after a lackluster launch.

The drugmaker in July launched the “Surprise, it’s insulin” campaign, which featured people casually using the inhaler-like product in public spaces, such as at a table at a restaurant. Havas Health developed the campaign. InTouch Solutions also works on Afrezza.

“Afrezza is a potential option for people living with diabetes who are resistant to initiating or intensifying insulin therapy so we are planning to include messaging that will resonate with these patients,” a Sanofi spokesperson said in the summer.

Other promotional activities included providing 54,000 sample packs to physicians, establishing a doctor-education seminar series and adding Afrezza to Sanofi’s free diabetes-management program.

But those efforts have done little to significantly boost sales.

A number of factors may have contributed to Afrezza’s low adoption among patients, including the novelty of inhaling rather than injecting insulin, weak insurance reimbursement and a FDA requirement that patients undergo regular lung tests.

Physician awareness may have been another issue. A Jefferies analyst in May polled 120 doctors and found 35% of them had not heard of the drug.

MannKind executives last year repeatedly assured investors that Sanofi’s marketing and sales efforts would boost awareness of the product. At the Jefferies Global Healthcare Conference in New York City last summer, MannKind’s Pfeffer predicted an uptick in prescriptions as soon as the DTC campaign launched.

“I have no doubt this is going to be the blockbuster product we thought it would be,” Pfeffer said at the time.

Goldman Sachs analysts had originally said that they expected Afrezza to generate sales of $2 billion by 2025. Earlier in 2015 they cut the 2025 forecast to $1 billion.

MannKind has undergone several leadership changes in recent months. Its CEO Hakan Edstrom stepped down in November, and last month the drugmaker announced that it had named Duane DeDisto to replace him.  

Sanofi is expected to announce its 2015 earnings on Feb. 9.