Novartis (NYSE:NVS) reported updated, post-hoc data for its sickle cell disease drug, crizanlizumab, in early October, and it plans to file this drug for regulatory approval before the end of next year. If it delivers on that timeline, then it could beat Ironwood Pharmaceuticals' (NASDAQ:IRWD) IW-1701 to the market, making its commercial prospects uncertain.

Crunching the data

There's a big need for new drugs that can help prevent pain from vaso-occlusive crisis (VOC) in sickle cell disease patients and, based on updated data from Novartis, it appears crizanlizumab could be an effective treatment. 

A man in a suit biting his nail.


Novartis conducted a post-hoc study of its phase 2 trial results and discovered more patients receiving its humanized anti-P-selectin monoclonal antibody, crizanlizumab, avoided having a VOC over 52 weeks than people receiving a placebo. Specifically, 35.8% of crizanlizumab patients who had experienced between two to 10 VOCs in the prior year didn't have a VOC over a 52-week period, compared to 16.9% of placebo patients.

Those with fewer VOCs in the previous year appeared to do better than those who had previously suffered more VOCs, but there were improvements relative to placebo in both of those subgroups.

Of those who had suffered between two and four events in the prior year, 40.5% of crizanlizumab patients didn't have a VOC in the 52-week period versus 24.4% for the placebo group. And, of those suffering between five to 10 VOCs in the prior year, 28% of crizanlizumab patients didn't have a VOC versus 4.2% of placebo patients.

There was also a benefit observed in people taking hydroxyurea, the most common treatment available today. In that subset, 33.3% of crizanlizumab patients were free of VOCs compared to 17.5% for the placebo group. 

A brewing battle

VOCs are unpredictable, and they're the main cause of hospitalization for sickle cell disease patients. Over time, VOCs can increase morbidity, cause stroke, and damage organs. Because there's a need for new therapies that can help these patients, Ironwood is conducting a phase 2 trial of IW-1701, an oral, soluble guanylate cyclase (sGC) stimulator.

IW-1701 has a different mechanism of action than crizanlizumab, but both drugs seek to reduce painful symptoms in patients. According to, IW-1701's study will wrap up in July 2019; given Novartis plans to file for crizanlizumab's FDA approval next year, that timeline appears to put it behind Novartis in the race to market.

It's anyone's guess if Novartis' conversations with regulators will go well enough to allow it to file for an OK next year, or if the company does file for an approval, the FDA will green-light its drug. However, the uncertainty for IW-1701 is greater because we've yet to see trial data showing it's effective and safe. Ironwood does expect to present data from a trial evaluating IW-1701 in another rare disease, achalasia, before the end of the year, though, so investors should gain some insight into it soon.

How it does in that trial will be particularly important because Ironwood plans to spin off its R&D pipeline as a new company, and IW-1701 is one of the most advanced drugs that new company will inherit. If it does well, then it would bolster the new company's outlook, but if it does poorly, it could make owning shares in the spin-off less intriguing. 

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