What to Watch for in RG-101 Post Regulus Therapeutics Executive Departures

As you will probably know already, Regulus Therapeutics surprised us this week with the sudden departures of both their CEO and CSO.  These two individuals also happened to be the insiders selling major positions in the stock earlier this year just days ahead of critical data to be released on their lead clinical candidate, RG-101 for the treatment of HCV ('Reading the tea leaves on Regulus insider sales').

While this would be a good reason for what looks like a sacking of the company’s two key executives (especially since the exodus came as a pair), for investors the all-important question is whether it is also related to bad news that we do not know about yet.  Most importantly, does this also have anything to do with the failure to report the viral resistance analysis which had been promised to us for the EASL meeting in April?

It is this analysis that will determine whether the miR-122 inhibitor can facilitate 4-week treatment regimens which must be the goal for this asset.  This is because RG-101 is the only serious long-acting agent out there in the HCV drug development arena and 4 weeks of oral, short-acting antivirals do not seem capable of getting rid of the virus. 

If there was no resistance to RG-101, based on the available data RG-101 given on week 4 would add ~6 weeks to deep viral suppression to the treatment regimen, in a way resembling a 10-week oral regimen which have much higher odds of viral clearance.  If viral resistance (and not waning drug levels as I am assuming) played a role in the rebounds seen in the single-dose study, then this would not necessarily be the case.  I say ‘not necessarily’ because even then, the risk of developing viral resistance to RG-101 should be much lower when given in combination with other agents as is the plan.

Take-home: I remain cautious (but not short any more) prepared to take advantage of another bout of panic selling that could come with the release of the resistance analysis.  The quality of the new leadership to lead the exciting microRNA platform will also indicate whether Regulus can finally live up to its original promise.  Long-term, whether precipitated by the insider sales or not, the changes should be good as morale at the company from what I can tell had been low.

PS: in more positive news, Regulus Therapeutics today reported that a first-in-man study with their second most advanced microRNA Therapeutic, RG-012 for the kidney-related orphan disease Alport Syndrome, has begun dosing.

Regulus Therapeutics RG-101 Continues to Have Potential in HCV Treatment Landscape

Having attended the International Liver Congress last week in Vienna, Austria, it has become clear to me that HCV is not going away soon.  Even in the US where progress towards its ‘eradication’ may be considered most advanced with about 1/5 of the known patient population treated last year alone (~250k), it will be an uphill battle to identify, treat, and pay for the millions more infected. Worse still, it is not enough to simply cure the existing pool of HCV patients, but also stop the cycle of re-infection (largely the result of injection drug use).

Treatment cost is one challenge and the current drug rationing approach leads to the counterproductive warehousing phenomenon where current medical intervention is focused on the patients with more advanced liver disease.  This is not only the hardest-to-treat population, but also allows the liver health of the previously less sick patients to deteriorate.  This obviously makes little sense also from a pharmaco-economical perspective when getting rid of HCV early on has now been shown over and over again to dramatically reduce HCV-related cirrhosis and liver cancer.

Another problem is the fractured treatment landscape that exists for the various patient populations (split up according to fibrosis/cirrhosis stage, genotype, co-morbidities, the rapidly growing concerns around drug-drug interactions, available/accessible meds etc) making it difficult for even the learned gastroenterologist to keep up with the latest developments and putting HCV treatment practically out-of-reach for the general practicioner.  

12-24 weeks remains the standard drug treatment duration with docs worrying about shorter treatment regimens being sub-optimal.  A triple regimen by Gilead after 4 weeks of treatment merely achieved a 27% SVR12 which in the DAA world is practically synonymous with a cure.  The best shot at shortening treatment duration may therefore come from Achillion with 6 week of DAAs achieving high cure rates in 'easy' patient populations.

While interferon is on the way out, it could make an at least transient comeback for the hard-to-treat genotype 3 where, in addition to cirrhosis, cure rates with the all-oral DAAs low (60-80%).

To sum it up, the liver community has expressed multiple times at ILC2015 that a short-acting pangenotypic regimen is an important goal in the development of new medications for HCV.   And if they paid attention at the oral late-breaker on Saturday, RG-101 is poised to play a critical role in filling this unmet treatment goal due to its long duration of antiviral activity following administration, regardless of genotype.

RG-101 update: more relapses, but thesis intact

The clinical investigators of Regulus Therapeutics presented a 20 week update on the phase I study in genotype 1, 3, and 4 patients with good to moderate liver health.  28 patients received study drug RG-101, 4 placebo.

At the primary endpoint on week 8 (reported in earlyFebruary), slightly more than half (15/28) of patients treated with RG-101 were below the level of quantitation (BLOQ).  According to the company, most of them were not only BLOQ, but undetectable (by sensitive PCR) at that.  This is a remarkable feat given that the GalNAc-conjugated phosphorothioate antisense molecule had been only given once.

According to the latest update, half of those patients eventually relapsed (7-8 depending on whether you count the patient that was lost to follow-up), most of them shortly after week 8.  Although the relapsers are slightly disappointing as in the short-acting DAA world undetectable virus for 8 (or better 12, SVR12) weeks following cessation of treatment is more or less equivalent to a full-blown cure.

Of course, the prognostic rules for a long-acting agent like RG-101 with a slower onset of antiviral knockdown ought to be different.  The notion that the viral rebounds were simply due to waning drug levels in the liver (and not due to viral escape mutations!), was supported by the biomarker analysis in the healthy volunteer part of the phase I study, also presented at ILC2015, where the trough in viral knockdown (~day 28) more or less coincided with maximal total cholesterol lowering as a predicted by miR-122 biology.

Of note, there was no apparent benefit of increasing the dose from 2 to 4mg/kg which was consistent with preclinical evidence that showed a declining liver/kidney drug ratio at 4mg/kg and maximal cholesterol lowering at 2mg/kg in humans.  This indicates that ASGPR receptor binding becomes saturated when too much GalNAc antisense is given at once.  The increased drug liver concentration at higher concentrations observed in earlier preclinical studies probably indicate uptake in non-productive compartments of the liver, including Kupffer and sinusoidal endothelial cells.

  

The hope is that with a second dose of RG-101 28 days after the first shot, maximal viral suppression can be maintained for at least another 4 weeks to stave off any viral comeback as seen in the single-dose study.  This is supported by both the healthy volunteer part of the study and the chimeric PXB mouse experiments presented which showed that such a second dose not only maintained drug potency, but in fact led to a step-up in efficacy.  I am therefore optimistic that with 2 doses of RG-101 monotherapy alone ~50% cure rates can be achieved in patient populations similar to that in the phase I study.

This, however, is not even the goal.  The ultimate goal would be to establish a simple pan-genotypic 4-week treatment regimen.  Accordingly, the combination of RG-101 with a DAA(s) (sandwich regimen) can be expected to result in a very, very deep viral knockdown by week 4.  At this point, a second shot of RG-101 would be administered to give the immune system another 6 weeks or so to finish off the virus.  I believe a very realistic scenario, and depending on which patient populations you are looking at a very compelling alternative to current HCV medications and those in development. 

PS: Open questions

Unfortunately, given that cholesterol lowering was still close to maximal at week 8, it would have been comforting to show a mutation analysis from the clinical study to confirm that viral relapse was not explained by the virus successfully developing resistance against RG-101.  This is such an obvious question that one wonders why Regulus did not present the data (yet). 

Another question mark around the current data set is why Regulus is not disclosing the differential effect of RG-101 on good and bad cholesterol and instead is reporting total cholesterol lowering.  The study investigator said that they are still analyzing the data from the multi-dose healthy volunteer study  (months after completing dosing???) and are planning to publish those.  I am mildly optimistic that this could unexpectedly bring to the fore the cardiovascular potential of miR-122 targeting, although in this case (à mostly chronic treatments) the liver cancer concern around miR-122 inhibition may be more valid than it is for the 2-shot HCV treatment goal. 

Simply Good: Regulus Therapeutics’ MicroRNA Inhibitor for HCV

Last year’s European Liver Meeting in London (EASL) was all about progress made in the treatment of HCV.  In addition to the expected buoyant mood among participants, questions were asked about a) affordability and even more so, b) the complexity of the treatment landscape. 

We have heard a lot about certain pricing pressures in the HCV space recently.  Although more and more observers are now calling an annualized $14-18B market in the US and Europe alone over the next 10 years one not worth pursuing, I happen to disagree, especially if you are talking about an $800M market cap company like Regulus Therapeutics (unlike $90-150B for Gilead and Abbvie) and the continued unmet need in this market.

Practicing physicians want simplicity

Part of the unmet need is the noted complexity of the treatment landscape.  These days, which drug and for how long you take it depends on a number of factors such as your HCV genotype and liver fibrosis score.  Based on  today’s data, RG-101, a microRNA inhibitor developed by Regulus Therapeutics may change this and simplify the life of the busy practicing physician.

Add to this the fact that some subpopulations, e.g. genotype III (~12% of the 3-4 million US HCV population) have standard of care cure rates (12 week daily Harvoni plus much-hated ribavirin) of just over 80% in clinical trials, not counting those who either do not get their prescriptions filled, nor the ~5% that get them filled, but then do not adhere to daily pill regimens. Real life, not clinical studies.

RG-101 potency paves the way for simplified regimen

Accordingly, mean viral load reductions of 4.8log were achieved following a single (!) subcutaneous administration of 4mg/kg (4.1log for 2mg/kg), making RG-101 the single most potent HCV drug ever tested.  Moreover, every subject responded, regardless of genotype and fibrosis score. 

Almost as impressive, for the 2mg/kg single dose cohort where day 84 (SVR12) data is now available, 4 out of the 14 given RG-101 were undetectable for the virus and could well turn out to be cured from just a single dose of drug.  In the same cohort, two were below the level of quantitation (BLOQ) on day 57, but rebounded thereafter.  This is hardly surprising given that liver concentrations at that time are predicted to be around 6% of the starting dose.      

Importantly, such a rebound is not the same as treatment failure due to the development of viral drug resistance.  A previous mutation analysis by miR-122 competitor Santaris (Ottosen et al. 2015) which has been developing a less potent anti-miR122 drug has shown that in Man (unlike in prolonged tissue culture experiments), no drug-resistant escape mutant to a miR-122 inhibitor is generated.  Such a high barrier to resistance can be expected from targeting a host factor rather than acting as a direct antiviral.

In cases of viral rebound, a simple second shot on day 28 or a higher dose of say 8mg/kg as I have been whining about for weeks now* would have kept the virus in check, if not eradicated it.

* Parenthetically, today’s data showed that I was right that there would likely be a further dose response from 2mg/kg to 4mg/kg with particular benefit with longer duration (see diverging curves particularly after day 22), also because in preclinical animal data, the liver concentrations increase linearly between 1mg/kg to 10mg/kg.  This is why I am surprised the company Is not talking more about the potential of 8mg/kg even though that dose was found to be safe in the healthy volunteer part of the study.

A sandwich regimen for all

The current data thus support that RG-101 could be the foundation for a universal HCV treatment regimen that looks something like that:

When a patient walks into the doc’s office to discuss his HCV treatment options, the doc convinces him that he should get treated and offers to give him the first shot of RG-101 at that visit that sits in his fridge.  This would take into account that some patients first say ‘yes’ to treatment, but then don’t get their prescriptions filled.  The doc then writes a prescription for 28 days of a potent oral DAA pill such as Harvoni and instructs him to start the pills any time within the next 14 days and asks him to come back after a month.

On that second visit, the patient will receive his second dose of RG-101, just to make sure and torch the earth for for the virus another 30+ days.  He then tells the patient to finish his pack of pills and come back in 6 months to confirm that he got rid of HCV.

Sounds simple enough to me.

Reading the Tea Leaves on Regulus Insider Sales

Revelations Friday night that the CEO (here) and CSO (here) of Regulus Therapeutics had sold sizeable amounts of Regulus stock just days ahead of an important phase I data release, initially sent shivers down my spine I could soon be ridiculed a 'bagholder' on Twitter and by Benitec shareholders.  

What confidence does it betray in the upcoming results when the CSO sells what appears to be ALL his shares in the company (worth ~$1.5M) and the CEO about a third of his holdings in his Family Trust  slightly more than a quarter of his combined position, including his Family Trust (~$710M for original position).  

Let me be clear, whether the stock goes up or down and regardless of whether these sales occurred according to a 10b5-1 insider trading plan (which can be cancelled anyway and thus makes them a farce), such shenanigans are unwarranted and officers of publicly traded companies should refrain from such actions.

Nevertheless, since I am doing nothing but wait for the results, let me indulge in providing a timeline to provide context to these sales.

October 22, 2014

Regulus reports truly stunning results where they reveal that a SINGLE dose of 2mg/kg of RG-101 was able to knock down HCV virus by over 4logs, with each patient, no matter the genotype, responding to the drug.  The company says that dosing in the next higher dose cohort, 4mg/kg, was ‘ongoing’ and results therefrom would be reported in Q1 2015.

November 5, 2014

On the Q3 2014 conference call, the company updated investors that the 4mg/kg cohort had then been fully enrolled. Maintains guidance of providing results sometime in Q1 2015.

November 12, 2014

At the Credit Suisse Healthcare Conference, the company narrowed down data release to occur in January 2015.

November 25+26, 2014

The two persons most familiar with progress with the clinical progress of RG-101, the CEO and CSO of Regulus Therapeutics, set up 10b5-1 trading plans that apparently foresaw the selling of Regulus shares last week.  IF the January 2015 data release guidance was made in good faith two weeks earlier, this means that they likely hoped to cash in after the results. Fair enough and well deserved- even if the trial is open-label and they thus likely knew where the knockdown curves were headed by that time.

December 3, 2014

A week after setting up the automated trading plans, at the Piper Jaffray Conference, the time frame for data release was widened and shifted back with ‘January-February’ which means that the sales would either occur before or after the results.

January 8, 2015

Regulus Therapeutics announces 2015 goals under their ‘Clinical Map Initiative’ according to which 4mg/kg results would be announced in ‘early February’, i.e. right after the planned share sales.

According to the above, the stock sales can be interpreted both to portend good or bad results.  One scenario is that the CEO/CSO may have originally wanted to cash in on what they knew were good upcoming results, but then lawyers became involved and said that this could draw some unwanted attention and the data release was slightly pushed back.  If the results would be good and the stock were to go up, they would look like heroes anyway and countless bonus options would come their way in perpetuity to more than compensate for the loss.

Another scenario is that they were afraid of an impending stock drop triggered by the 4mg/kg data and simply wanted to get ahead of that train wreck.  Par for the course in biotech.  But in that case, I’m wondering why they wouldn’t just sell their shares well ahead of the event to avoid the attention they now have.

Until now, Regulus Therapeutics has been a comparatively credible and fairly low-key publicly traded biotech company to the degree that until October 2014 they had not even recognized the jewel that RG-101 could become for the company.  Besides the animal pharmacokinetics-human efficacy relationship, it is one of the reasons why I am long RGLS going into the results, believing the market is yet to appreciate the full value of RG-101.  Unfortunately, the insider sales have somewhat shaken this belief and I hope management will learn from it. 

RG-101 for HCV: Give Me 8mg/kg

Last October, Regulus Therapeutics announced stunning data from an ongoing trial of anti-miR122 RG-101 for the treatment of HCV infection.  Accordingly, 6 out of 14 patients administered a single injection of 2mg/kg of the GalNAc-conjugated antisense oligonucleotide dropped to what the company referred to as ‘below the level of quantitation’ (BLOQ) by day 30 and remained there as of the update (day 57 for those treated first in the study).

*BLOQ is not the same as 'undetectable'.  It is 'undetectable' for x number of weeks that technically defines a cure.

2mg/kg data looking ever better

The more I look at the data (here for the corresponding dataset), the more intrigued I get.  For starters, the 2mg/kg was only the starting dose in the patient cohort.  Moreover, a patient that had been more recently treated and had reached only 29 day in late October seemed to be on his way to BLOQ.  In fact, after his titers had dropped to below ~1000 IU/ml, viral decline seemed to accelerate as if a threshold had been reached. 

Overall, it seemed that as long as you got below ~1000 IU/ml, the virus would not rebound (at least until day 57).  Accordingly, the 5 patients that rebounded got close (1000-10000 IU/ml), but never below the apparent threshold.  The lack of overlap between the individual knockdown curves also suggest that viral rebound is not the result of stochastic escape mutations, as is often the case in HCV, but simply due to diminishing drug concentrations.

This leaves two patients which as of the update were still slowly declining as if the threshold rule was counterbalanced by declining oligonucleotide concentrations in the liver after day 30.

In summary:

Everybody responded irrespective of genotype and starting viral titers, of these…

…6/14 BLOQ;

…3/14 undecided;

…5/14 nadir of 1000-10000 IU/ml, then rebound.

A one-shot cure?

In the current marketplace, comprising of ~12M untreated HCV patients in the top 7 pharmaceutical markets plus hundreds millions more in the rest of the world, HCV treatment success has less become a function of viral cure rates achieved in clinical trials, but more one of compliance with the pill regimens.  Therefore, a therapy which would shorten current treatment regimens (say to 4 instead of 8-12 weeks), or even involve just one or two subcutaneous administrations in the physician’s office as part of routine checkup visits, would have great pharmacoeconomic impact.

The company is currently crunching the numbers for the next higher, 4mg/kg cohort.  In general, with RNAi and antisense therapeutics, what you see with increased doses is a slight acceleration of gene knockdown (thereby shifting the knockdown curves down), and, likely of more importance in this case, extended duration of drug activity.

The latter is supported by animal, including non-human primate data that showed that liver concentrations of RG-101 increase linearly with dose from 1-10mg/kg.  This means that for the 3 undecided patients in the 2mg/kg cohort, a doubling of the drug concentration could have easily pushed them BLOQ.  

Alternatively, a second dose of 2mg/kg on day 29 would have achieved that as also supported by animal data showing that viral nadir drops further when a second dose is given (on the left is an example from the challenging chimeric mouse model).

I am less sure whether the other 5 patients would have gotten there with 4mg/kg, but would be much more sanguine about it with a dose of 8mg/kg.

A mistake not to escalate to 8mg/kg

Unfortunately, Regulus Therapeutics stated last year that based on biomarker data which measures the activity of human genes naturally regulated by miR-122, 4mg/kg would be the highest dose to be tested in HCV.  This is because the biomarker response seemed to have saturated already by 2-4mg/kg.  This despite of the fact that they had established in the same phase I study that 8mg/kg is also safe and well tolerated in non-infected healthy volunteers.

I clearly think that stopping at 4mg/kg is a mistake.  First, I highly doubt that at least in terms of duration of biomarker activity, they did not see improvements with higher doses (show me the data).  Second, it is wrong in my opinion to assume that drug saturation with regard to microRNA activity against endogenously expressed genes is a good reflection of microRNA activity in the context of viral replication.  In this case, the rationale is further in question because of the special way miR-122 acts in HCV replication (increases, not decreases activity).

Tempering expectations

As we await the 4mg/kg data and an update on the 2mg/kg cohort in ‘early February’ according to recent company guidance, I should caution that the above scenario suggesting a one-shot monotherapy cure is within reach is obviously an unbelievably exciting best-case scenario.  There is a lot which could make the market react adversely to the upcoming data.  This includes emerging side effects, and responses that could even be worse than the 2mg/kg data, e.g. if some patients do not respond at all or if the company is right in their biomarker assumptions which due to chance could make the 4mg/kg data look worse numerically. 

Therefore, my base case for market-neutral data is that all patients will have to respond, and that the extent of the response will be similar to that seen with the 2mg/kg dose.  But then again, I’m looking at the data and keep thinking to myself…’8mg/kg might be the one-shot cure that could transform HCV treatment’.  In any case, the company has little to lose from dose escalating to 8mg/kg.

Anti-MiR122 Therapeutic Stuns HCV World with Single-Dose Efficacy Results

This morning, Regulus Therapeutics greeted us with amazing results from a phase I study of RG-101, an anti-microRNA 122 oligo for the treatment of HCV infection.  The results show that in the exploratory HCV-infected patient subgroup, a single dose of 2mg/kg of RG-101 resulted in a mean viral load reduction of 4.1log on day 29.  All responded with viral declines, with 6 and 3 of the 14 patients with viral levels below the level of quantitation on days 29 and 57, respectively.   

These results even exceed my own wildest imaginations (as discussed here yesterday) and I’m amazed how much this virus, in all patients, seems to have come to rely on this host-derived microRNA for replication and/or genome stabilization.

It is not clear whether increasing the dose to 4mg/kg, the pre-planned upper dose in the HCV-infected cohort for which dosing is ongoing will bring any additional benefit given that the biomarker data (host genes targeted by miR-122) from the healthy volunteers showed a plateau already at 2mg/kg, indicating the power of this GalNAc chemistry approach.  My guess is that the main benefit from a higher dose would be a decrease in response variability.

Interestingly, IL-28 status, frequently a predictor of treatment success, did not influence the results, nor did HCV genotype seem to have an impact (small numbers).  This further supports that RG-101 could fill some of the more attractive opportunities in the current HCV market.   

Regarding safety, mild and transient injection site reactions seemed most significant with no serious adverse events in the entire study, including the healthy volunteer cohorts (up to 8mg/kg).  This is also consistent with data for Alnylam’sALN-TTRsc which uses a similar GalNAc chemistry and where multiple doses up to 10mg/kg had been tolerated, with injection site reactions, especially at 10mg/kg, being the main safety finding.   

So what’s it all worth?  The results position RG-101 to facilitate a 4-week HCV dosing regimen (compared to typically 8-12 weeks currently), potentially in combination with a single direct-acting antiviral such as Olysio by Johnson&Johnson.  One or two injections maximum.  Great compliance, potentially pan-genotypic, ideal for the busy practicing physician who does not have the time nor inclination to know the ins and outs of each DAA.

In dollar terms, I’d like to think that with this drug profile, this overlooked compound and company are worth as much as what Merck recently paid for HCV drug developer Idenix: $3.85B. The market valuation of Regulus before the news: $300M.  Needlessly to say that I'm long the stock.

PS: GSK once had rights to a precursor compound of RG-101 which it did not exercise.  Importantly, at the time, Regulus’ anti-miR122 compound was not GalNAc-enabled.  This would have necessitated much more frequent dosing and higher dosages and resulted in less potent and more protracted viral declines, i.e. something that would not have been competitive in the current HCV marketplace.  But as often the case with Big Pharma and cutting-edge technology, today’s data clearly shows them wrong.  It has to be said though that GSK more or less got out of HCV which also would have explained GSK’s decision RE anti-miR122.

PPS: Congrats to Peter Sarnow and Catherine Jopling who in 2005 made the mind-boggling discovery that HCV relies on a microRNA for its replication.  I hope they will be handsomely rewarded for it.

Predicting the Outcome of Regulus HCV microRNA Therapeutics Study

Regulus Therapeutics is on track to reveal phase I results of its anti-HCV compound by the end of the year according to a presentation at last week's OTS.  Although the phase I study is largely a healthy volunteer dose-escalating safety study, it does involve a cohort of HCV patients to assess the viral knockdown kinetics following a single dose of anti-miR122 RG-101. 

MicroRNA-122 is a small RNA host factor that had been identified to play an important role in HCV replication.  As a therapeutic target it promises a low risk of viral resistance, pan-genotypic activity, and entirely novel mechanism of action making it suitable for combination therapy.

Based on the experience with an LNA-based competitor compound by Santaris/Roche (Janssen et al. NEJM 2013), I predict a 2 to 3 log viral knockdown, with a 3 log viral knockdown setting the scene for RG-101 as a single shot in a 4-week treatment regimen in combination with other oral direct-acting antiviral agents (DAAs).  If viral reductions were on the low end of my expectations, it may require 2 or 3 doses within 4 weeks for GalNAc, cET-enhanced RG-101 to facilitate such a short treatment period which is considered a necessary attribute of future treatment regimens in an increasingly competitive market.

Miravirsen comparison

Earlier studies by Regulus competitor Santaris/Roche largely form the basis for my predictions.  In particular, a phase II study of 5 weekly doses of miravirsen at 3, 5, and 7mg/kg yielded 1.2log (3mg/kg) and ~3log (5 and 7mg/kg) viral knockdowns.  Miravirsen is an LNA-based antisense compound whereas RG-101 involves the analogous high-affinity cET chemistry.  Conservatively, miravirsen has a slight (1-3x) potency advantage over RG-101 without the GalNAc conjugation when considering non-human primate and clinical AldoA and cholesterol results which reflect anti-miR122 activity.

However, the GalNAc conjugate in RG-101 is giving it a great 10-30x boost in potency, meaning that overall RG-101 should be 3-30x more potent than miravirsen.  It is because of this and considering that RG-101 is given at 2 and 4mg/kg in the phase I trial in HCV patients, that I arrive at a predicted 2-3 log HCV reduction in the phase I study.  This also makes the conservative assumption that 3log viral reductions is all that an anti-miR122 treatment strategy may achieve based on the apparent plateauing of miravirsen at 5mg/kg.  The 3 log prediction would require that a single shot of RG-101 can already achieve super-therapeutic tissue levels of the oligo.  This, however, cannot be assumed given that for non-ligand-targeted phosphorothioate antisense technology at least this would normally require a multi-dose loading schedule.

But isn’t RG-101 late to the HCV game?

It’s long been thought that it’s game over for RG-101 given the dynamics in the HCV markets.  In particular, the already approved and soon-to-be-approved all-oral DAAs which typically achieve cures in >90% of patients in 8-12 weeks in well-supervised clinical trial settings, would make newer agents like RG-101 seem outdated.  On the other hand, especially given cost pressures (~$100K per average treatment and ~4 million infected in the US alone), the uptake of the new treatments has been relatively slow with only 1-2% treated thus far (according to some of the analyst reports that I have read).  And even then, the sales have been spectacular: Sovaldi e.g. is on track to become the most successful drug launch ever being on track for more than $10 billion in sales in its first launch year!!!

It is the cost pressures (pricing per pill, not per cure) and improved adherence that make a shortened 4-week treatment period so desirable.  A single or two subcutaneous injections in the doctor’s office during routine check-ups where blood is taken anyway should add to compliance.  Holding the subcutaneous route of administration of RG-101 against the drug is therefore wrong in my opinion and the ‘all-oral’ notion, a misnomer really, has only been so attractive because the former subcutaneous standard of care, interferon, was so unpopular not because of the needle injections, but because of its side effects.

So place your bets.  I believe RG-101 has value and will not only be superior to the Santaris/Roche drug, but has pretty much caught up with it in development terms given that miravirsen has only been tested with a DAA (telaprevir) that is already long outdated.  As to the necessary Big Pharma/Biotech licensee, Johnson&Johnson tops my list.

Disclosure: Long RGLS as an RNA Therapeutics stock waiting to be re-discovered with an increasingly broad and clinical-stage pipeline and good financials.  The RG-101 results should only be the trigger for the re-discovery of this ~$300M market cap company.