RNAi Drug Trounces Antisense Rival in Paris ATTR Showdown

The audience gasped when Alnylam finally revealed the full dataset from the APOLLO trial in ATTR amyloidosis.  For the first time, patients and docs will have access to a drug that not only delays or just barely halts, but starts to actually reverse disease manifestation in a majority of patients afflicted by this debilitating, multi-systemic disease. 

Efficacy: reversal versus slow progression

A few minutes before the Patisiran RNAi data presentation, Dr. Benson, the lead investigator from the corresponding NEURO-TTR with rival antisense drug Inotersen was not met with nearly as much awe.  Yes, Inotersen did delay disease progression and was quite a bit better than the placebo control.  However, unlike Patisiran (-6 at 18 months), the mean change from baseline in the critical mNIS+7 score was well in positive territory (+5 at 15 months) indicating disease progression.

As such, Inotersen does not appear to be much better than TTR tetramer stabilizer diflusinal (given off-label in the US) which registered a +9.2 score in a trial over 24 months compared to +29.6 in the control.

Patisiran similarly came out ahead in the quality of life (QoL) assessment (improvement versus in this case a halt for Inotersen), although this was not a primary endpoint in the APOLLO trial. 

The NEURO-TTR trial could score some brownie points here as it not only made QoL a co-primary endpoint, it also scored positively in another patient-reported health score, SF-36.  Although investigators seem to prefer ‘hard’ outcomes measures such as the mNIS+7 and biomarkers, regulators and payors seem to prefer QoL endpoints according to comments at the meeting.

That the efficacy was better for Patisiran should probably not have surprised too much given that its knockdown was slightly better (82% mean median in APOLLO) than that of Inotersen (according to Benson: 75-79%, although I am a bit skeptical here as I do not understand what this range means).

As a side note and although everybody likes to see Patisiran versus Inotersen as an either-or issue, if you combined them both, you would easily exceed the 90% amyloid source protein reductions that amyloid researchers believe is necessary to allow tissue clearance exceed fresh amyloid deposition.

Safety: Patisiran once again exceeds, Inotersen disappoints expectations

If you still had difficulty deciding whether to take a drug that likely makes you better or a drug on which you will likely progress, the relative safety profiles should remove any remaining doubt.  Contrary to suggestions by the ‘counter-detailers’ at Ionis, Alnylam could not find any evidence that the steroid treatments to prevent untoward reactions around the time of infusion had any measurable adverse impact on patient health. 

Maybe this should not come as a surprise either given that immune suppression is given only transiently, every 3 weeks.  To make it clear, none of the many cardiologists in the audience voiced any concerns throughout the two days of the conference (where Patisiran was the star) about steroids in patients with cardiac disease manifestations.

If anything, the Patisiran group suffered from less adverse events compared to the placebo group, probably the result of addressing the disease.

The same, namely exceeding expectations, could unfortunately not be said for Inotersen: in addition to the previously disclosed renal and platelet SAEs, there was a 5:0 death imbalance against the drug candidate.  While the drug-related thrombocytopenia case had already been known and the 4 other deaths were attributed to disease progression, one cannot but notice that strangely, when it comes to safety, all the disease-related, random events always end up going against the Ionis drugs. What a coincidence!  And given that Ionis partner GSK had abandoned Inotersen even before the APOLLO trial were announced, I am wondering what other safety findings (in addition to thrombocytopenia, renal AEs, pyrexia, chills, and nausea) will come to light with the FDA briefing documents next year.

Take-home

Alnylam and the RNAi field could not have hoped for better outcomes from the high-profile APOLLO trial.  If anything, the full results presented at this first European combined patient-doc ATTR conference are more impressive than first indicated by the topline data a month ago.

And regarding the competitive profile compared to the antisense rival, it makes me wonder about the magic of feeding into a biological mechanism that has evolved to do just that: gene silencing.

There are still some questions around the label that these data will support.  Importantly, how much credit will be given to the positive cardiac outcomes since these were not the primary focus of the studies?  But since this is a multi-systemic disease and given the totality of the data, a number of doc presenters made it clear that they will be looking hard for polyneuropathy manifestations in ATTR patients to justify (to payors) treating them with the new agents.

Disclosure: I am short ALNY since the stock may be gasping for air up here, at least in the short-term; long IONS since this public humiliation by the fiercest rival may make them realize that in the orphan drug age, commercialization is a must.

Two Promising RNA Therapeutics to Face Off in Paris ATTR Amyloidosis Meeting

I’m en route a high-speed train to Paris to witness how RNA Therapeutics are starting to revolutionize the care of patients afflicted by ATTR amyloidosis.  Towards that end, the presentations on pivotal trials with Patisiran (APOLLO; RNAi) and Inotersen (NEURO-TTR; ASO) to an audience of key opinion leaders and patients at the inaugural European ATTR meeting will critically inform the adoption of these medicines.

Top-line data for these agents in the polyneuropathy-leaning form of the disease (FAP) have been disclosed previously (here and here).

This will only be the beginning though, with more potent, safe, and better tolerated follow-up RNA Therapeutics being developed and patient identification becoming more sophisticated.  Ultimately, I envision a world where, for the inherited version of the disease, patient identification based on genetics will be possible such that TTR lowering therapies can be initiated before organ damage through TTR deposition occur.

Patisiran seen leading

When Alnylam disclosed a month ago that intravenously infused Patisiran not only halted disease progression as had been reported for Ionis’ subQ Inotersen, but apparently improved symptoms compared to baseline, the stock shot up ~60% while Ionis stock dived ~15%. Furthermore, safety and tolerability looked solid with much less treatment discontinuations (7.4% vs 37.7%) and nominally less deaths observed in the Patisiran treatment arm versus placebo control (4.7% vs 7.8%). By contrast, Inotersen has been living under a safety shadow ever since deaths due to phosphorothioate ASO-dependent thrombocyte lowering wereseen in addition to renal toxicity.

Can Inotersen stage a comeback?

So even before Patisiran data were presented, the Big Pharma partner for Inotersen, GSK, dumped the drug (by not exercising the option).  Obviously, Ionis wants this to be seen as an act of Dumb Pharma throwing away highly valuable drugs under the directive of bean counters and smartly dressed corporate overhaulers (here: GSK leaving orphan drugs).  Nevertheless, it is difficult to believe that GSK gave rights to Inotersen back for free when it saw Inotersen competitive with Patisiran which easily accounts for roughly half of Alnylam’s  $11B market cap.

Still, while to many it is a foregone conclusion that today’s presentations won’t change much in the competitive dynamics between Patisiran and Inotersen, there are a few scenarios which could change it.

Firstly on efficacy, we still have to learn whether the disease improvement over baseline as reported for Patisiran by Alnylam is medically meaningful over the disease halt reported for Inotersen.  As such, it is possible that the (mean and median) mNIS+7 scores were barely negative (i.e. nominal improvement) as the phase II open-label extension trial results with Patisiran would have predicted.  And who knows, mNIS+7 values for Inotersen could actually be nominally negativ!

Somewhat complicating mNIS+7 matters is that the two companies are using slightly different scales, but I don’t expect this to have much impact on the discussion.

In addition to closing the gap on absolute efficacy, Inotersen could emerge as the winner in terms of treatment efficacy versus placebo.  Importantly, the placebo group in the Patisiran study received steroid treatment around the time of infusion since Patisiran treatment entails this to manage potentially dangerous reactions around the time of infusion and subsequent hours.  Although Patisiran clearly outperformed placebo, steroids, albeit given intermittently, should have some impact on perceived disease symptoms and I found it notable that while Inotersen was statistically better than placebo (no drug at all) at an intermediate time-point 9 months, Patisiran wasn’t yet at 8 months.

It’s therefore possible that Inotersen has the delta advantage over Inotersen which, of course, would influence how docs regard the inherent efficacy of Patisiran alone.

Finally, the placebo issue could also negate another apparent advantage of Patisiran over Inotersen: safety and tolerability. Notably, there was a ~40% SAE rate in both the Patisiran and placebo groups which are historically high for TTR amyloidosis clinical trials.  For example, an 18 month trial with TTR tetramer stabilizer Tafamidis had SAEs of less than 10%.  Is it therefore possible that steroid treatment accounts for the high SAE rate and that the overall SAE rate for Inotersen (to be disclosed) is much lower? 

 With the presentations being less than 8 hours away, we shall find out any time now as my train reaches the outskirts of Paris…