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…

RNAi Therapeutics Become Real

It’s been a long ride.

The lives of quite a few of us has been consumed now for close to two decades dreaming about a world in which RNAi Therapeutics have real-world clinical impact.  Yesterday, that dream has officially materialized.

TTR knockdown improves disease state

With the conclusion of the most comprehensive clinical study conducted to date in the severe orphan disease ATTR amyloidosis, Alnylam and investigators have found that prolonged knockdown of the causative transthyretin (TTR) gene improved both objective (mNIS+7) and subjective (quality of life) measures of the main manifestation of the disease, peripheral neuropathy.

There is no doubt that this was the result of on-target TTR gene knockdown since this was a strictly controlled study in which the only difference to the placebo group was the administration of the RNAi formulation.  Furthermore, results from a similar study for this indication (NEURO-TTR) by Ionis earlier this year in which related RNaseH antisense oligonucleotide technology was utilized for TTR knockdown also demonstrated disease benefit, albeit a ‘mere’ halt of neuropathy progression in QoL as opposed to the improvement seen here (note: mNIS+7 was reported only with regard to placebo, not versus baseline).

Importantly, this extra benefit is likely explained by the fact  that the Patisiran RNAi formulation had been shown to be slightly more potent than antisense drug candidate Inotersen in earlier-stage studies (here and here).  While considering a ~80-85% vs ~70-75% knockdown may not seem much at first glance, protein deposition, clearance and in particular misfolding that is at the root of the disease are higher-order concentration-dependent processes (think about crystallization) so a difference of ~17.5% vs ~27.5% (>50% more remaining than with Patisiran) remaining insulting protein may well be highly meaningful. 

Of note, phase II data from Patisiran have demonstrated that the ~80-85% knockdown was able to somewhat tilt the tables in favor of TTR tissue clearance, but also that it was not able to fully do so.

It is therefore of utmost importance to push forward with the development of the even more potent GalNAc-enabled RNAi candidate ALN-TTRsc02.  Preliminary phase I data from that candidate suggest that it should be able to reduce TTR levels to 5% or less with subcutaneous dosing as infrequently as every 3-6 months (Patisiran: intravenous every 3 weeks; Inotersen: weekly).

Why this is such a big deal for RNAi Therapeutics

As I had indicated in last week’s post, the phase III APOLLO results represented a make-or-break moment for RNAi Therapeutics.  If it turned out that RNAi- and delivery-related side effects were to outweigh the benefits of gene knockdown at the conclusion of this decade-long, high-visibility program, the financial markets would have reacted violently and starved the industry of the cash necessary to more fully develop the technology (Alnylam with its cash reserves at least would have mounted a comeback eventually).

If it’s one thing I’ve learned about biotech money matters over the last 15 years of riding the RNAi rollercoaster, it is that the perception of a technology is as important for its continued development as its intrinsic technological validity.

Personally, I am most relieved in that the small, but often pervasive transcriptomic off-target changes introduced by an RNAi trigger (à microRNA-type off-targeting) did not have an apparent detrimental effect on the target organ (here: liver) after prolonged, 18-months treatment.  This should not be entirely surprising based on what we’ve learned about microRNA biology- not all targets of a microRNA are biologically relevant- but is still a great relief to see play out in practice.

To wit, the RNAi industry has been overly focused on potency when selecting RNAi trigger sequences for clinical development and mostly relied on bioinformatics for specificity. Indeed, Alnylam has paid the price for this negligence in that certain RNAi triggers, such as the one for its original alpha-1-antitrypsin program, have caused liver tox most likely due to microRNA-type off-targeting.  It is therefore finally employing chemical strategies such as the incorporation of modified nucleotides in the seed region of the trigger to bias the RNAi apparatus towards RNAi cleavage instead of microRNA-type message destabilization. 

This strategy was first reported by Rosetta Inpharmatics (now Merck) and had then been developed further in the commercial realm by Marina Biotech which then licensed the IP to Roche (then acquired by Arrowhead) and possibly others. 

It will be some time until we have complete certainty that microRNA-type off-targeting won’t rear its ugly head again, but the odds should be getting better and better with the employment of best practices. More generally, Patisiran is only the beginning of a long string of real-world impactful RNAi Therapeutics.

SNALP Works!

The long wait is finally over: Systemic RNAi delivery has been proven in Man. No 'ifs' or 'buts'. Alnylam just announced that Tekmira’s SNALP-enabled ALN-TTR01 reduced target transthyretin (TTR) protein levels in ATTR patients in a dose-dependent manner- without causing an elevation of liver enzymes or serious adverse event (SAE).

Following preliminary evidence in Tekmira’s TKM-ApoB study, this is the long-awaited moment where there is no doubt that successful systemic RNAi delivery has been achieved. With already about half a dozen SNALP-based programs in or very close to the clinic, this result de-risks a major segment of the RNAi Therapeutics pipeline and should stimulate further investments in SNALP-enabled RNAi Therapeutics development as well as provide a boost of confidence to the entire sector.

Today's presentation at the FAP meeting in Kumamoto can be found here. For a more detailed background on ALN-TTR01 for ATTR, please read yesterday’s blog entry.

In the phase I study (single-dose, dose-escalating), 5 patients received 1mg/kg, the highest planned dose. At this dose, there was a mean reduction of 41% in serum TTR levels from baseline. Despite the small patient numbers and natural TTR variability, this was stat significant at p=0.02 relative to placebo. While this level of knockdown may not seem dramatic and may or may not be useful for eventually achieving a therapeutic effect in ATTR patients, it is important to keep in mind that the other liver-targeted SNALP programs employ formulations that should be at least 10x more potent than the one used in TTR01 and probably also slightly better tolerated. As such, this was a stringent test for the safety and tolerability of SNALP technology and bodes well for the commercial potential of particularly the liver-targeted SNALP pipeline following TTR01, including TTR02 for which an IND is expected by year end.

The time course of TTR protein suppression in one patient provided a picture-book example of bona fide RNAi knockdown in Man. Consistent with the now extensive experience with SNALP in pre-clinical animal models, including non-human primates, this patient exhibited a rapid onset of knockdown (63% reduction at 48 hours) which became a peak knockdown of 81% a week after drug administration with 50% suppression still being observable 4 weeks after this single dose. There is no doubt that this was an RNAi-mediated response.

Preclinical repeat dosing studies have shown that in order to maintain the same level of gene suppression, one can reduce the amount of drug given at subsequent doses. This also means that perhaps giving patients two or three loading doses of 1mg/kg within a week or so may allow one to achieve the 70-80% knockdown with ALN-TTR01 not just in select patients.

Importantly, the safety profile seems to exceed even my own expectations. Unless Alnylam will reveal major immune stimulations in the upcoming conference call (at 8.30am Eastern Time; note added in proof 11/23: none were revealed), the only mild-to-moderate adverse reactions seemed to be infusion reactions that were experienced by 3 out of the 23 TTR01-treated subjects and which was well controlled by simply slowing the infusion rate. As the same was seen in the SNALP-enabled ALN-VSP02 study, it seems that this risk factor is indeed well manageable. What is more, even at the high dose of 1mg/kg, there were no signs of liver toxicity as evidenced by increases in liver function tests. As SNALP-RNAi for ATTR will be a chronic treatment, this should be the major safety focus in the future.

Whatever Alnylam decides to do with ALN-TTR01 (I expect it to remain on the shelf as a viable alternative pending TTR02 results), today represents a milestone in the history of RNAi Therapeutics and I do believe that we have seen the bottom in RNAi Therapeutics. Credit belongs to Alnylam for pushing ahead with the SNALP clinical studies. Alnylam has a truly gifted, and in many ways inspirational drug development team, but it is probably also this talent that has made them blind to what they are actually entitled to. My sympathies are therefore with Tekmira today as it has developed (and owns) the delivery technology that is turning out to be quite literally the savior of RNAi Therapeutics: SNALP. Clinical results eventually follow strong science.

Do you believe that your writing style or English language skills put you at a disadvantage in publishing your research? OxTERMS can help you.