Going into 2018, OligoRx Has Become Mainstream Drug Modality

When I became interested in drug development almost 2 decades ago, I just didn’t get it: why was it that gene-centric biotech was seen as an esoteric, money-losing endeavor, and why did shot-in-the-dark small molecule drug development represent the pharmaceutical elite?  After all, biology has fully moved into molecular gear and how could medicine not follow that?

After a quarter of a lifetime I now understand that what makes sense often takes a decade or two to manifest.  So if you are dead sure about your view of the world, stick to your conviction and resist the urge to follow the herd.

The gene-centric drug development revolution has occurred, long live Oligonucleotide Therapeutics

In 2018 though, gene-centric drug development has taken the pharmaceutical world by storm.  This just 8 years after gene therapy, RNAi, and oligonucleotides were widely ridiculed for having been hyped and supposedly failed.

Yes, in 2017, antisense drugs Spinraza (for spinal muscular atrophy) and Exondys 51 (for Duchenne muscular dystrophy) made a big commercial splash, RNA knockdown for TTR amyloidosis proved positive in 2 large phase III trials, all the while the first gene therapy products (2 CAR-T cell/gene therapies and 1 ocular gene therapy) got approved.

This momentum will only pick up speed on 2018.  The year is already starting with an onslaught of drug development VC investments prominently featuring mRNA and gene-modulation startups (e.g. $270M investment in personalized/mRNA oncology Co bioNTech, and ~$100M for gene processing plays ExpansionTherapeutics and Stoke Therapeutics).

 

Further down the pipeline, we should see approvals and commercializations for at least 3 important oligonucleotide therapeutics drugs: Patisiran (RNAi/Alnylam) and Inotersen (RNaseH antisense/Ionis) for TTR amyloidosis in addition to Volanesorsen (RNaseH antisense/Ionis-Akcea) for lowering triglycerides.  At the same time, Sarepta will continue to walk the tightrope with their first-generation PMO splice skippers for DMD hoping for approvals of additional exons.

RNAi drug Givosiran should also be speeding towards approval in 2018.  After a sweet and brief phase I/IIa study sponsor Alnylam is pursuing a laser-like direct-into-pivotal study/biomarker-based approval strategy.  Expect this to become quite commonplace rather than the exception, especially under the new FDA.

Adding gravitas to all these activities will be the further commercialization successes of Spinraza and Exondys51 that will break down pretty much all commercialization barriers that may have been put up by payors.  After all, these are all delay tactics intended to save the system a few billion dollars (at the cost of childrens’ lives mind you), get a few bureaucratic underlings promoted, but really won’t stand a chance against the desire of patients and their families to get access to such foundational drugs.

It is my belief that with the commercial successes of Spinraza and Exondys51, all previous reservations with regard to oligonucleotide therapeutics being mere scientific tools rather than real-world drugs have disappeared among pharma and investors.

RNAi Therapeutics Stock Thoughts for 2018

Moving on towards the investment end of the business, Alnylam will be a show-me stock which will have its ups and downs as the market will challenge Patisiran sales numbers against its $12B market cap.  Alnylam knows this and is throwing everything behind the commercialization of Patisiran to the extent that it renegotiated its platform deal with Sanofi to retain full global responsibility for commercializing Patisiran and follow-on ALN-TTRsc02.

The easiest RNAi money in my opinion will be made with Arrowhead Pharmaceuticals (~400M market cap) which has impressed me recently with the vengeance with which it is getting back into the clinic (IND equivalents filed recently for its HBV and AAT drugs) and between it and Amgen it could have brought half a dozen drug candidates to the IND stage within the span of just one year (from having zero in the clinic!).  Just by executing on bringing these drugs to the clinic, Arrowhead’s market cap should exceed those of genome editing high-fliers like Sangamo and Editas (~$1.5B).

The topping on the cake, however, will come from potentially first proof-of-concept biomarker data from their GalNAc programs by the end of the year.  And who knows what will happen to the stock if they can declare HBsAg seroclearance based on the legacy HBV program (ARC-520/1)!  And this is not all as we have yet to learn more about Arrowhead’s lung delivery platform which could be a very big franchise onto its own without much competition.

In terms of striving towards first proof-of-concept and critical biomarker data for its GalNAc RNAi platform, Dicerna is similar to Arrowhead.  The difference is that Dicerna’s goals are not as grandiose as those of Arrowhead (Arrowhead is built to become a $50-100B biotech juggernaut) focusing its resources on a few (ultra-)orphan indications which they are addressing with much care and detail.  At a market cap of $450M after the recent conversion of their convertible debt, the downside could be enormous should the lead program for primary hyperoxaluria stumble.  The upside, however, is also significant as they have their eyes set on 2 orphan drug approvals by 2023.

Critically for Arrowhead, Dicerna, and other companies in the space, given the positive news from Spinraza and Exondys51 sales and TTR trial results, the resistance of more conservative investors to invest in second-tier companies so they can grow into substantial multi-billion companies themselves should also be alleviated.

Finally, investors in Ionis Pharmaceuticals face a critical year.  No, this time it’s not about hitting clinical endpoints and how well their drugs are selling.  Instead, Ionis will have to decide its corporate future.  Run away if it makes the mistake of continuing to try and dominate every area of oligonucleotide therapeutics development.  It is this ambition and resulting lack of focus that is responsible for the company giving away much of the commercial upside of its drugs to its partners.

As the basic oligonucleotide chemical building blocks and designs are coming off patent and more and more disease-focused, nimble companies come online, this train has left the station.  Boy, this company is in dire need of fresh management blood from the outside world. 

The macroeconomic environment also bodes well for a blockbuster oligonucleotides stock year: low inflation and interest rates, good economic growth at low unemployment, lowered corporate taxes in the US and an FDA that seeks to speed up and protect innovation in exchange for ensuring that off-patent drugs are highly affordable.  It is probably this blue sky, however, that scares me most and it is my New Year’s resolution to take it easy on my margin balance for a change.

First RNAi Therapeutic Nearing Finish Line

ALN-TTR02 for the treatment of TTR amyloidosis is the most advanced RNAi Therapeutic in clinical development and has been carrying the torch for the field as whole. Expectations are therefore high and a stumble in this program as a result of the therapeutic hypothesis underlying the program not panning out would likely trigger a temporary*, but steep sector-wide sell-off.  

* it should be clear, however, that with the current ability to robustly knock down genes in the liver, RNAi Therapeutics will result in a number of successful treatments.

It therefore came as a relief yesterday when Alnylam presented (press release here, data slides here) 12-month data from an open-label extension phase II study of ALN-TTR02 in the polyneuropathy form of the disease (FAP) showing

a)      continued robust gene knockdowns for more than a year (88-80% reductions peak/trough in 3-week cycle);

b)      disease stabilization (if not improvement) when the Natural History of the disease would have predicted marked deterioration (predicted mNIS+7 at 12 months of +18 in Natural History vs ~-2.5 on ALN-TTR02).

Furthermore, the safety of this liposomal formulation enabled by Tekmira seemed more than sufficient for a disease as severe as FAP TTR amyloidosis (5-15 year survival following diagnosis) with the most significant adverse events being related to the intravenous route of administration meaning that ALN-TTR02 should be given under trained medical surveillance.

There are some questions that remain open, some of which should be answered by the ongoing phase III APOLLO study which should complete sometime in 2016 (with an 18 month primary endpoint).

Firstly, it will be important to show disease stabilization to be strictly related to ALN-TTR02.  In the phase II study, most patients (20 of 27) were on tetramer stabilizers which have previously shown to result in very modest (tafamidis) to moderate (diflusinal) therapeutic benefits.  While neither tafamidis nor diflusinal have shown disease stabilization after 12 months, the concern remains that they could have contributed to the apparent therapeutic benefit seen in the phase II study.

To my surprise, the 7 patients not taking tetramer stabilizers on top of ALN-TTR02 seemed to do even better, at least numerically than those taking them (-6.5+/-9.2 vs -1.1+/2.5).  Although the number was quite small, the fact that this is the opposite result from what one might have expected, it is possible that a slight placebo effect may have played a role in this open-label study: those for which ALN-TTR02 was the only medical intervention might have had a greater ALN-TTR02-driven placebo effect.

Other more complicated explanations based on TTR lowering affecting the PK/PD relationship of tetramer stabilizers are also possible if this phenomenon is for real.

Fortunately, the blinded phase III APOLLO study will compare ALN-TTR02 to patients taking no tetramer stabilizers to treat their FAP.  Finally, it would be of interest to look at the effect of ALN-TTR02 on the spleen in the APOLLO study as spleen toxicity due to lipid stability might be the most important safety parameter with chronic dosing.    

In summary, yesterday’s 12-month data removed important overhangs over the RNAi sector and we are on track for the first commercial RNAi drug in 2017. Seeing is believing.

Injection Site Reactions and Liver Toxicity Emerge as Major Issues for GalNAc-siRNA Technology

Alnylam this morning reported top-line results from a phase II study of their first clinical candidate based on the GalNAc-siRNA conjugate delivery technology, ALN-TTRsc for TTR amyloidosis.  Accordingly, average knockdowns of ~85% were seen in the 5mg/kg dose group, thus confirming the robust potency at around the dose that the company plans to take forward in later-stage studies.

Such potency, however, came at the apparent expense of relatively frequent injection site reactions (23% of patients), with an additional skin reaction seen outside the area of injection.  Moreover, there was a trend towards elevated liver enzymes, a marker of liver toxicity, including one that was adjudicated a serious adverse event (SAE; ~4x ULN deemed mild severity).

The efficacy data do not come as a surprise given that they were largely in line with that seen in the phase I study a year ago, which included the same dose group (5mg/kg) at the same dosing schedule (first 5x daily, then weekly for 5 weeks).  In both cases average TTR reductions  of ~85% were seen, with the difference being that this study involved 23 subjects at this dose (plus 3 subjects at 7.5mg/kg which was not further pursued for undisclosed reasons) while the phase I study involved only 3 comparable subjects.

The efficacy is thus in line with the intravenous ALN-TTR02 which utilizes Tekmira’s liposomal delivery technology and which so far has been very well tolerated.  Critics (aka LNP haters), however, are keen to point out the use of (transient) immune suppression.  The efficacy of ALN-TTRsc is superior to the antisense compound by ISIS and GSK which has shown 70% target gene knockdown in a short 4-week phase I study.  Assuming maximal knockdown efficacy has not been reached at this time-point, ISIS-TTRRx is likely to max out between 75 and 80%.

Similar to potency, the injection site reactions were not really a surprise given that in the phase I study this was the most common side effect.  What is new is that there was a skin reaction that occurred outside the area of injection possibly indicating systemic immune activation.

The liver enzyme elevations, however, were certainly new.  This could be related to histologic observations of granulations in the cytoplasm of hepatocytes, likely reflecting storage sites of the fairly stable modified RNAi triggers.

My hope and expectation is that particularly the injection site reactions, but also liver enzyme elevations will lessen with the lower doses enabled by the more effective second generation ESC GalNAc chemistry.  Still, for ALN-TTRsc the safety profile looks adequate for an indication like FAC (familial amyloidotic cardiomyopathy), but 23 is still a small number to be sure.  

Lastly, if I had to choose between ALN-TTRsc, ISIS-TTRRx, and ALN-TTR02, I would go with ALN-TTR02 with the best apparent risk:reward, regardless of whether it's an intravenous procedure or not.   

Disclosure: Long ISIS Pharmaceuticals, no positions in Tekmira and Alnylam.

Phase I Study of ALN-TTR01 in Transthyretin Amyloidosis- A Preview

(For a discussion of the phase I results, see here).

Alnylam is about to reveal results from its phase I study with ALN-TTR01 for the treatment of transthyretin amyloidosis (ATTR) at the Nov20-22 FAP meeting in Kunamoto, Japan. This blog provides a brief overview of the rational for RNAi Therapeutics in this disease and the importance of this particular study for the field of RNAi Therapeutics.

ATTR is an autosomal dominant amyloidotic disease due to point mutations (>100 possible) in the TTR gene. These mutations cause protein misfolding and aggregation into fibrils that, depending on which tissues they accumulate in, can cause various organ dysfunctions, most notably polyneuropathy (FAP), cardiomyopathy (FAC), and gastrointestinal/nutritional defects. For those that develop the disease, death is common 5-15 years following the emergence of disease symptoms (usually between 30 and 50 years of age). Although there is genotype-disease phenotype overlap, the most common mutation, Val30Met, strongly predisposes to FAP, while the Val122 is associated with FAC. About 10,000 patients suffer from FAP and 40,000 from FAC. As a rare genetic disease, it occurs in clusters, with FAP cases for example concentrated in Portugal, Sweden, and Japan.

Until recently, the only accepted treatment has been liver transplantation for FAP where removing the source of the mutant TTR in blood serum can reverse the polyneuropathy. Pfizer just got European approval for FAP with its small molecule TTR conformational stabilizer Vyndaqel based on slowing the rate of peripheral neuropathic impairment.

There exists, however, great need for additional therapies as Vyndaqel actually missed the primary endpoint in its pivotal study (the FDA did not accept the NDA for review earlier this year), and because liver transplantation is ineffective for FAC. The latter seems to be due to wildtype TTR still being able to deposit into pre-existing plaques, for example in heart tissue, at a rate that is higher than the turnover of the amyloidotic plaque. In fact, the amyloidotic potential of wildtype TTR is illustrated by the fact that it frequently causes spontaneous amyloidosis in elderly people (senile ATTR).

RNAi Therapeutics Approach to ATTR

The contribution of both wildtype and mutant to disease pathology, the dynamic turnover of plaques, and the fact that TTR knockout mice have the same life expectancy and fertility as their wildtype littermates and are otherwise essentially asymptomatic, makes RNAi Therapeutics a highly attractive treatment approach for this disease. TTR is involved in the transport of vitamin A and thyroxine in the blood, but it appears that in the absence of TTR these carrier functions are compensated for by other carrier proteins in the serum. What is more, essentially all the life-limiting pathologies are caused by TTR that is expressed in the liver, and with Tekmira’s SNALP delivery technology, RNAi can address the relevant gene expression.

TTR01 vs TTR02

One source of confusion that I expect to affect the financial markets tomorrow stems from Alnylam developing two candidates for ATTR, ALN-TTR01 and ALN-TTR02, the difference between the two candidates being in the SNALP lipid composition. TTR01 is the subject of the present trial and is based on an early DLinDMA lipid-containing formulation. It was shown to be effective in knocking down TTR in non-human primates with an ED50 of around 0.3-0.4mg/kg. As the highest dose in the phase I study was 1mg/kg it is reasonable to expect there to be evidence for TTR knockdown in the ALN-TTR01 trial. I should warn, however, that because of the small patient number in each dose cohort and the natural intra- and inter-patient variability of TTR levels in the serum, the pharmacodynamic outcome measure in this trial, the pooled numbers may not give us a straightforward 'stat-significant' answer.

Because of the rapid developments in improving the efficacy and tolerability of SNALP technology, it is therefore almost assured that Alnylam will drop TTR01 and prioritize TTR02 which takes advantage of these developments and for which the filing of an IND is imminent.

Consequently, the importance of tomorrow’s results for the RNAi Therapeutics field lies in providing proof-of-concept for RNAi knockdown following systemic delivery at OKish tolerability. That’s it. It also sets up the results from the phase I studies with ALN-PCS02, the PCSK9-targeting hypercholesterolemia candidate, which are expected to be reported by the end of this year. As PCS02 uses one of the more recent SNALP formulations, this will be the SNALP candidate that has to shine both in terms of knockdown efficacy and safety/tolerability.

ATTR Economics

If you had any doubts as to the commercial potential of ATTR, it is worth noting that Vyndaqel, Pfizer's just-approved TTR drug, is expected to be priced at more than 100,000 Euros per patient year and that most (known) FAP patients are in healthcare systems that will still bear such costs. Pfizer last year paid $200M in upfront considerations for FoldRx, the original developer of Vyndaqel, with another $200M in contingent milestones. Although FoldRx has a mission of developing other protein folding-based drugs, this price tag was essentially for a drug with results from a pivotal trial that failed to meet the primary endpoint and for which approval was far from certain. Considering Alnylam’s cash position, this one registrational drug candidate valued FoldRx higher than all of Alnylam- although you might justify that with the mounting existential risks stemming from Alnylam's alleged theft and misuse of Tekmira's SNALP technology.

Given these economics, it is not surprising that other companies have similarly recognized the commercial potential of ATTR. Importantly, ISIS Pharmaceuticals will also present progress with its antisense candidate for ATTR (ISIS-TTRRx) at the meeting. This candidate entered clinical development in May and is financed by GSK which retains an option for its exclusive license.

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