It was something of an up-and-down week for IPOs: Two biotechs, Alzheimer’s focused Alzheon and brittle bone drug company Mereo BioPharma pulled their collective $161 million Nasdaq attempts, but we ended the week with better news.

Inflammatory disease biotech Kiniksa Pharmaceuticals said late Friday it was seeking out a meaty $100 million IPO, while antibody biotech Scholar Rock, on the same day, filed for a $75 million IPO.

First up is Kiniksa, which is at work across several autoinflammatory and autoimmune conditions, with three clinical-stage product candidates, including one slated for a phase 3 this year.

One of these is a Regeneron drug, Arcalyst (rilonacept), an interleukin-1 blocker that is used to treat cryopyrin-associated periodic syndromes (CAPS). It’s looking to rework the drug in pericarditis, a debilitating inflammatory cardiovascular disease, for which it says there are currently no FDA-approved therapies. It’s in an open-label phase 2 proof-of-concept and slated to report preliminary data this year.

It’s also at work on mavrilimumab, an old MedImmune drug, which works as a monoclonal antibody that antagonizes the signaling of granulocyte macrophage colony stimulating factor, or GM-CSF. It’s working on the drug in giant cell arteritis, an inflammatory disease of the blood vessels that can lead to blindness, if left untreated.

Phase 2 trials are set for this year, although it has had a difficult path, given that MedImmune initially sought trials for the drug in rheumatoid arthritis, but its IND for that test was slapped with a clinical hold in 2010 before human data had been gathered, as it appeared to heighten the risk of pulmonary alveolar proteinosis.

"Since then, in 2014, the FDA acknowledged that clinical studies in refractory RA may be appropriate based on MedImmune's clinical studies in Europe in which it dosed over 550 RA patients with mavrilimumab and generated an aggregate of over 900 patient years of exposure with no evidence of PAP," Kiniksa said in its SEC-1.

MedImmune did, however, withdraw the IND for mavrilimumab for the treatment of RA, with Kiniksa now hoping it can prove its worth in giant cell arteritis.

The Lexington, Massachusetts-based company was founded in 2015 and plans to list on the Nasdaq under the symbol "KNSA."

And then there’s Scholar Rock, which wants a $75 million IPO, and comes just four months since it got off a $47 million series C round.

That money, and what it can take from its IPO, should all go to plan, is set to take its treatment for spinal muscular atrophy (SMA) into the clinic, as it seeks to find out whether its myostatin blocker can best the underwhelming performance of one-time rivals from companies including Novartis.

Scholar Rock specializes in conditions in which growth factors are key, a focus that positions it to target a wide range of diseases including cancers and fibrosis. The near-term focus is on neuromuscular conditions, specifically SMA.

The biotech is looking to SRK-015, an inhibitor of the supracellular activation of latent myostatin, to improve outcomes in this population by boosting muscle strength and motor function.

Companies including Novartis, Amgen spinout Atara and Shire have swung and missed at myostatin in recent years. Scholar Rock, which ceded a significant head start to them, has always maintained that SRK-015’s targeting of upstream processes gives it an edge over the competition. And Scholar Rock and its investors’ belief in that idea has survived the clinical failures of other myostatin drugs.

It’s also in the hunt against companies including partners Biogen and Ionis, with their SMA drug Spinraza (nusinersen) and the experimental gene therapy from AveXis, which was just bought up by Novartis, with its AVXS-101 candidate.

Scholar Rock plans to test its drug as a monotherapy in subpopulations of SMA patients and more broadly in combination with drugs that upregulate production of SMN, a protein that is deficient in patients with SMA. Biogen’s Spinraza is such a drug.

The later-than-expected move into the clinic has given Scholar Rock time to branch out beyond its initial focus on neuromuscular diseases. Johnson & Johnson-partnered cancer candidates are making their way through target validation and discovery, as are in-house programs targeting fibrosis, autoimmune diseases and hematology.

The Cambridge, Massachusetts-based company was founded in 2012 and plans to list on the Nasdaq under the symbol "SRRK."

It’s likely that the two previously pulled IPOs were not indicative of the window closing on what has been a buoyant IPO market for biotechs this year, but rather related to the companies themselves, most notably Alzheon, which was seeking an offering in a disease that has seen nothing but setbacks and growing skepticism that it can move the needle anymore than the likes of Lilly, Pfizer, Axovant, Merck et al., could.

Meanwhile, London-based Mereo BioPharma withdrew its $80 million attempt, blaming "challenging stock market conditions." But that wasn't the tale told by Morphosys, which got off an oversubscribed $208 million IPO just the week before, with similar successes across the board for biotechs over the past year.

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