What’s Sanofi’s answer to the sluggish launch of orphan drug Kynamro (mipomersen)? Put more troops on the ground.

ISIS Pharmaceuticals said last Friday during the biotech’s fourth-quarter earnings call that its marketing partner, Sanofi, will add more reps in response to what ISIS COO/CFO Lynne Parshall called a “slow start.”

The brand, which was co-developed and is now marketed by Sanofi’s Genzyme unit, was approved in January 2013 for treating HoFH (homozygous familial hypercholesterolemia), a rare cholesterol disorder. Another drug for the same condition, Aegerion’s Juxtapid, was approved the month prior, setting the stage for a rivalry.

ISIS, under a profit-sharing agreement with Sanofi, earns a portion of the drug’s overall profits rather than sales. Sanofi doled out $25 million to Isis in January 2013 in a milestone payment after the drug’s FDA approval. Neither ISIS nor Sanofi reported the drug’s sales in their quarterly earnings statements. 

When asked by an MM&M reporter how many reps were being added, Genzyme would not divulge the number, only that it did increase the force.

Nor has Isis divulged the number of patients taking Kynamro. Parshall declined to provide it to an analyst who requested it during the Q&A session, saying, “Yes, we know how many patients are on Kynamro but that’s information Genzyme considers at this point to be competitive intelligence—we’re not free to give you that.”

“While not providing [the number] of patients on therapy,” Jefferies analyst Eun Yang wrote in an investor note this morning, “ISIS indicated Kynamro’s launch by Sanofi/Genzyme got off to a slow start (as we previously predicted); Sanofi has increased its sales force to drive sales.”

Genzyme’s rival in the HoFH area, Aegerion reported unaudited 2013 net product sales of between $48 and $49 million, according to various news reports. Juxtapid is the firm’s only marketed product.

Juxtapid is an oral pill for daily use and carries a price tag of $295,000 per patient per year. ISIS/Genzyme’s Kynamro involves a subcutaneous injection and is currently priced at $176,000 per patient per year. Kynamro, as a biologic, also requires cold storage.

Coinciding with the company’s decision to add reps in support of the launch was an increase in physicians certified to prescribe the drug. ISIS’s Parshall noted during the earnings call that “there are hundreds of physicians who haven’t [been] certified to prescribe Kynamro. We believe that the increase[d] number of prescribers will translate into increase[d] prescription of patients on the drug.”

Kynamro, due to the potential for liver damage, is only available to providers who undertake the manufacturer’s FDA-mandated Risk Evaluation and Mitigation Strategy (REMS), which educates potential prescribers about the risk of hepatoxicity (chemical-induced liver damage) and also ensures they’re treating patients with HoFH. Juxtapid requires a similar REMS program.

Yang forecasts that ISIS could see profit-sharing payments up to $5 million by next year, and up to $18 million by 2018.