Tag Archives: RNAi

Moderna Therapeutics as the next Genentech? Not so fast

By Steve Dickman, CEO, CBT Advisors

December 10, 2012 (slightly shorter version originally published on TechnologyReview.com)

Quick biotech PR tip: When exiting stealth mode, heralding your company as the next Genentech is one way to get above the noise. That was the approach of Moderna Therapeutics, a Cambridge, MA-based startup that announced itself last Thursday, revealing that it had raised more than $40 million and attracted an all-star set of board members and scientific advisers.

Announcing that you just might be on the way to becoming Genentech II raises the bar a wee bit. And, at first blush, Moderna looks like it might even get over that very high bar.

Central Dogma of Molecular BiologyThe concept is intriguing, to say the least. Biology’s central dogma is “DNA to RNA to protein.” Although Nobel Prizes have been won for discoveries that expand upon that central dogma (the discovery of reverse transcriptase, for example), the core approach underlies the first several generations of biotech products. Think EPO, Neupogen or the grandfather of them all, human insulin. You manipulate the DNA in the lab and then express the protein in the production facility. Then you put it in a vial and sell it to the patient, who gets an injection or an infusion. The main role for the dogma’s middleman, messenger RNA (mRNA), is a passive one: get transcribed from the DNA then, in turn, get translated into protein.

Moderna turns the dogma on its head: go straight to the RNA, do some fancy chemical tricks to it and deliver it directly into the body. This makes the patient herself into the production facility. All of us carry around cellular protein factories, known as ribosomes, and if properly activated, those can be harnessed (at a much lower cost) to produce proteins in which we have deficiencies.

One report on Moderna, published on Xconomy, quoted venture investor Noubar Afeyan of Flagship Ventures as saying that the company “builds on lots of things that have been tried before.” One of those things is gene therapy, providing genes (that is, DNA) via viruses or other delivery vehicles and trying to get cells to express those genes. Those approaches, too, tried to use the body as a manufacturing facility. Unfortunately, with some recent intriguing exceptions, most of them have failed.

Aside from this novelty, three things make Moderna so interesting:

Breadth of application

Since the mechanism is potentially so universal, proteins could be produced that address any number of diseases. The company said it will focus first on areas where protein therapeutics are already well-established: oncology supportive care, inherited genetic disorders, hemophilia and diabetes. But the company also claimed that it can also induce production of intracellular proteins that could never be given exogenously due to efficacy or immunogenicity concerns. Should this approach work, and it’s a bit of a long shot, it opens up new areas of application to the pharmaceutical industry.

Repeat dosing

Unlike many gene therapies, which could potentially be curative, in Moderna’s case the patient will need to be dosed with the mRNA over and over again. Think “recurring revenue stream.”

Intellectual property

When Genentech and Amgen were founded, neither one had a monopoly on the production of all human proteins in bacteria. When monoclonal antibodies were invented in Cesar Milstein’s laboratory in Cambridge, UK, Milstein was discouraged from patenting the concept. But in Moderna’s case, filing broad and deep intellectual property was the company’s central focus and a big reason why the company remained in stealth mode for the past two years. This means that even if other companies manage to enable the use of mRNA-based techniques in areas not yet explored by Moderna, the company could still demand royalties.

Yet another reason to pay attention to Moderna: unlike many other biotech companies, Moderna was not based on work published soon after its founding. The original publication that drew interest from Afeyan didn’t involve using patients as protein factories at all. The paper, published by company founder Derrick Rossi in 2010, involved using injected mRNA to produce cells that resemble embryonic stem cells. According to the Xconomy article, Afeyan did not want to invest in a stem cell company, which he perceived as too risky. Instead, he suggested that Rossi use the mRNA as a way to induce protein production in patients. That led to the key experiments, as yet unpublished, that were the basis of the company’s intellectual property and its initial financing. According to Moderna’s triumphant press release, the publications are supposed to come in 2013.

At the same time, there are three big questions:

Delivery

Isn’t Moderna facing a double hurdle, first in selectively getting into the right kind of cell and then in achieving the right therapeutic dose level? The first of these hurdles represents the same kind of delivery problem that has presented such an enormous challenge to RNA interference (RNAi) companies like Alnylam. For all its promise, RNAi was born amid a hail of questions expressing doubt about delivery. How to use systemic delivery to propel nucleic acid molecules with strong negative charges and potentially vulnerable to ribonucleases into the right cell types in the right organs at high enough concentrations to have a biological effect? That was the question. (The early results, as I viewed them in a cramped biochemical laboratory in Kulmbach, Germany, in 2002, looked blotchy at best.) More than ten long years later, despite some powerful efforts that cleverly take advantage of biological reality, for example, the “leakiness” of tumors, those questions have still not been completely laid to rest.

The other part of the delivery challenge has to do with what happens to the mRNA once it is inside the right kind of cells. How many cells exactly has it penetrated? What are the expression levels over time of the desired proteins on a per-cell or per-tissue basis? Will the levels in one patient be the same as in the next one? Achieving appropriate dosing without setting off alarm bells at the Food and Drug Administration will be tough.

Where are the other investors?

The only institutional investor named in the press release was Flagship Ventures. If other VC firms were involved, one would expect to find them sharing the limelight. So either Flagship decided that what it had in Moderna was so good, it did not want or need to share or other VC funds were approached and said no. It will be interesting to learn over the coming weeks which of these explanations, or which combination of them, pertains.

What’s the value in its first applications?

Let’s assume that the Moderna approach works. Suddenly EPO, Factor VIII and beta-globin can all be produced in patients deficient in these proteins simply by dosing them regularly with mRNA. But so what? There are already therapies on the market that will be doing this. In fact, some of those will be going generic and will be joined on the market by “biosimilars” that will presumably cost less than the existing (expensive) drugs. Furthermore, many of today’s most successful protein therapeutics have been modified (e.g. pegylated) to improve their half-lives. Where would be the advantage of an injection of mRNA over one of protein, especially a second-generation, long-acting protein such as Amgen’s Neulasta®?

Perhaps the advantage would come in proteins that cannot be injected as such because they elicit unwanted immune reactions from patients. But there are not too many examples that come to mind (thrombopoietin is one). That might be one reason why Moderna CEO Stéphane Bancel said that the company would be partnering the largest-market indication areas, like cancer, while retaining only rare diseases (in which intracellular protein production might make sense) for itself.

In summary, Moderna reflects a novel approach. For that, its founders and visionary investors deserve their well-earned day in the spotlight. It is especially commendable that a venture investor in the current no-whip, Splenda-only funding environment would create a good old-fashioned full-fat latte of a biotech company. Funding it exuberantly, vigorously protecting the IP and keeping the shares to yourself are all probably wise moves. But for the rest of us to see Moderna as a new Genentech, Moderna will have to publish in a peer-reviewed journal, partner with a pharmaceutical company or at least explain how it addresses basic questions like delivery and consistent dosing across tissues and patients.

# # #

2 Comments

Filed under Startup

Exosomes: The Little Vesicles That Could

A Boston Biotech Watch guest post by Dima Ter-Ovanesyan*

When I mention to other biologists that I work on exosomes, I am used to getting blank stares. Exosomes, also sometimes called microvesicles, are small lipid vesicles secreted by all cells. Like many dark corners of biology, the exosome field is a province of a few experts and is still largely unknown to the mainstream. But thanks to some exciting early results and a long list of potential medical applications, exosomes are beginning to move out of the shadows and into the light. Exosomes were the subject of two sessions at the annual American Association of Cancer Research (AACR)  meeting earlier this month. In January, the first-ever conference on exosomes brought together more than two hundred researchers from around the world. And now even the popular press is picking up on the applications of exosomes to RNA interference (RNAi) drug delivery and diagnostics in fields ranging from cancer to diabetes.

The concept of cells budding off small particles was actually first mentioned in Charles Darwin’s The Variation of Plants and Animals Under Domestication in 1868 and exosomes were first observed by electron microscopy in the 1980s. For twenty years after that, exosomes were thought by many to be nothing more than “cellular trash bags” that dump proteins deemed to have outlived their “use-by” date. This changed a few years ago, though, when a number of independent studies showed that exosomes actually contain not only protein but also RNA. This discovery opened the possibility of using the RNA in exosomes floating around in bodily fluids to learn all kinds of secrets about the cells that release them.

Charles Darwin

There first (as usual)

I learned about the diagnostic potential of exosomes in early 2009 when a venture capitalist asked my opinion on a business plan. The company, called Exosome Diagnostics, was being spun out of Massachusetts General Hospital (MGH) to develop new diagnostics based on analyzing the RNA in exosomes isolated from blood and urine. At the time, I was an undergraduate at MIT working on microRNAs. After reading the business plan, the patent filing, and the underlying scientific publication, I called the VC back. “This could be HUGE,” I told him. “We should get in on this,” he replied, and promptly forgot all about it. I did not. After graduation, I opted to learn more about exosomes through a brief stint at the Curie Institute in Paris. I then joined Exosome Diagnostics, which by then was flush with a $20M Series A.

The company’s platform is based on the work done at MGH, which showed that mutant RNA transcripts derived from key genes can be detected in exosomes released by cancer cells. Johan Skog and colleagues had shown that by isolating exosomes from blood and looking at the RNA inside, they could tell whether a patient’s tumor contained mutant EGF Receptor (EGFR) – establishing the proof of principle for exosomes as companion diagnostics. Oncologists could use them to peer into the genetics of tumor and decide whether a patient would be a good candidate for EGFR-inhibiting drugs such as Tarceva® and Iressa®. As pharma companies move increasingly towards targeted cancer therapies coupled to companion diagnostics (think PLX-4032, Plexxikon’s BRAF inhibitor for melanoma, or Crizotinib, Pfizer’s ALK inhibitor for lung cancer), the appeal of a blood or urine test instead of a biopsy to analyze specific mutations is not hard to see. This is particularly advantageous in cancers where obtaining a biopsy is difficult, like brain cancer or lung cancer.

I think that companion diagnostics in cancer are just the tip of the iceberg for exosomes in diagnostics. Several recent studies have shown that different levels of certain RNAs in exosomes and other vesicles isolated from blood correlate with different disease states. In other words, exosomes have RNA “signatures” for different diseases. One recently published study , for example, showed that a specific microRNA in vesicles derived from diabetics’ blood was elevated compared to vesicles taken from non-diabetics. Amazingly, the researchers also showed that this biomarker could potentially be used to identify patients who will get diabetes before any clinical symptoms occur. Although the test in the paper was not yet sensitive enough for the clinic, the results raise the intriguing possibility of using RNA signatures to predict disease, not just diagnose it.

Several reports at the January exosome conference highlighted diagnostic applications of profiling exosomal RNA in different diseases:

  1. Signatures of mRNA isolated from exosomes in the blood could be used to classify brain tumors based on aggressiveness.
  2. A specific microRNA isolated from exosomes in the cerebrospinal fluid (CSF) was found in brain trauma patients but not in healthy controls.
  3. Certain microRNAs isolated from exosomes in the blood of pregnant women could be used to predict premature births.

Although larger studies will be needed to confirm these effects, I imagine that, in the not too distant future, exosomes will join the list of proteins and metabolites currently profiled during routine blood draws. Through methods such as high-throughput sequencing, the RNA inside exosomes (dare I say “exo-transcriptome”?) will be analyzed and will prove spectacularly useful in helping physicians assess and track patient health.

Exosome Micrograph

I spy a novel class of biomarkers (Image courtesy Johan Skog and Casey Maguire, Massachusetts General Hospital)

Exciting as the potential of exosomes is in diagnostics, you may be wondering what they actually do. Are the different RNA profiles in exosomes more than a correlation? Do exosomes actually contribute to disease? This was an intense topic of debate at the exosome conference, and, after listening to four days of presentations on the topic, I would venture to say that we still really don’t know. The fact that exosomes contain RNA raises the extremely intriguing possibility that cells throughout the body communicate by sending each other little “packages” of RNA, and the RNA can then perhaps act in the recipient cells – be translated into protein in the case of mRNA or repress the expression of other genes in the case of microRNAs. And, if this is the case, one could imagine hijacking this pathway to deliver therapeutic RNAs and thereby overcome an enormous roadblock.

The main obstacle to realizing the tremendous potential of RNAi therapeutics is the challenge of delivery. Whether or not exosomes are actually used to transfer RNA between cells remains to be proven, but results presented at the exosome conference and recently published by a group at Oxford made the first attempt at this approach. Led by Matthew Wood, the group loaded modified exosomes with an siRNA designed to knock down the BACE1 gene implicated in Alzheimer’s Disease.  Although they used healthy mice as models, the researchers demonstrated proof-of-principle by showing reduced levels of BACE1 in the brain. Of course, it would be reassuring to know what exosomes actually do in the body before injecting them into patients, especially given that exosome-based drugs would be complex biologics composed of several different proteins, not just lipid vesicles. As we learn more about the biology of exosomes, however, I could imagine scientists designing exosome-mimicking particles with the minimum necessary components to carry the RNA therapeutic to its designated site in the body.

As evidenced at the exosome sessions at the AACR meeting, there is increasing interest in exosomes secreted by cancer cells. Cancer exosomes have been found to contain oncogenic mRNA and proteins, and it is thus tempting to speculate that exosomes may have a role in modifying the tumor microenvironment and helping the cancer spread. If true, one could even imagine using therapeutics to specifically target cancer exosomes. Unlike with the use of exosomes for diagnostics, however, the use of exosomes for therapeutics will require scientists to uncover some of the fundamental biology of what exosomes are and how they function. Luckily, as evidenced by the excitement at the exosome conference, there are at least two hundred of them up for the challenge.

# # #

*Dima Ter-Ovanesyan (dimatero@gmail.com) graduated from MIT in 2010 with a Bachelor of Science in Biology. At MIT, he worked on RNAi screens in cancer with Michael Hemann and microRNA targeting with Chris Burge and David Bartel. He was also an associate at CBT Advisors. He currently works at Exosome Diagnostics.

4 Comments

Filed under Uncategorized

Great week for Spiegelmers, other nucleic acid drugs points to brighter future

Great week for Spiegelmers, other nucleic acid drugs points to brighter future

by Steven Dickman, CEO, CBT Advisors

Spiegelmers, the new drug class consisting of mirror-image aptamers created by Germany’s NOXXON Pharma, achieved an important clinical milestone this week. The next day, the lead antisense product of Prosensa garnered one of the largest recent pharma-biotech deals (potential total value: $680 million) from GSK. Taken together, these announcements provide validation not only for Spiegelmers and antisense drugs but also for nucleic-acid-based drugs in general.

It is my belief that nucleic acids, especially aptamers and RNAi but also some other categories, hold huge promise for drug development, a belief that has been validated by pharma interest in some areas (think RNAi) more than in others (gene therapy). What is still missing are late-stage clinical successes and sales: the only two nucleic-acid-based therapies to make it to the market, Isis’ Vitravene™ for AIDS-related eye disease and Eyetech’s Macugen™ for wet AMD (partnered with Pfizer then sold along with the parent company to OSI Pharmaceuticals), have had at best limited marketing success.

According to a company press release from Monday 12 October, NOXXON’s Spiegelmers were safe, well tolerated and had good PK and mechanism-related effects in the Phase 1 trial of the company’s chemokine inhibitor NOX-E36. The trial was carried out earlier this year in 72 healthy UK volunteers. This bodes well, of course, for the company, and for the Spiegelmers product class, for which this was the first clinical trial. Indeed, any lingering concerns about immunogenicity caused by the non-physiological nature of Spiegelmers (see Fig. 1) were allayed in this trial. In terms of safety, the molecules came through with flying colors.

Fig. 1: Through the looking glass – twice. Spiegelmer precursors are synthesized against a mirror-image version of their protein target; the actual spiegelmers are mirror-reversed versions (created from L-RNA nucleotides) of the best binders (Image courtesy Medgadget.com)

Fig. 1: Through the looking glass – twice. Spiegelmer precursors are synthesized against a mirror-image version of their protein target; the actual spiegelmers are mirror-reversed versions (created from L-RNA nucleotides) of the best binders (Image courtesy Medgadget.com)

In the CBT Advisors database, we’ve listed eight broad categories of nucleic-acid-based therapeutics besides gene therapy (see Table 1 below for an excerpt) as well as the most advanced entrants in each category. After a boom in the early-to-mid 1990s, at a time when Gilead Sciences was raising money as an antisense company, this diverse group has fallen on harder times. RNAi’s progress has been slowed by delivery challenges. Antisense is also moving more slowly through clinical development than optimists had expected. Macugen, launched in 2005, sold well only until two antibodies from Genentech, Lucentis and then Avastin, quickly took over the wet AMD market. Generally, aptamers and other nucleic-acid-based drugs have not yet fulfilled their initial promise.

This could change soon, though, based on three factors: these drug classes’ ability to hit targets inaccessible to conventional chemical approaches; their quick cycle times during drug discovery based upon the use of techniques that mimic natural selection; and rapidly improving delivery modalities. One brief example of each area:

Hitting new targets

NOXXON’s Spiegelmer drug E36 targets MCP-1, a chemokine (short for monocyte chemoattractant protein-1) that docks on the CCR-2 receptor on cells in many tissues. Almost all other molecules directed toward this pathway that are in clinical or even preclinical studies target not MCP-1 but rather its receptor CCR-2. The advantages of targeting MCP-1 itself remain to be proven in efficacy studies but they could be significant: greater potency, better pharmacodynamics and faster response time are all strong possibilities. Plus, in contrast to antibodies, Spiegelmers are chemical entities that do not require biologics production facilities. Data from this first-ever clinical trial of Spiegelmers showed dose-linear pharmacokinetics and a dose-dependent decrease in peripheral blood monocytes, consistent with the mode of action of NOX-E36 – neutralization of MCP-1. And of course, approaches like Spiegelmers that target the signal MCP-1 could also be used to complement existing approaches targeting the receptor.

Quick cycle times

Like its fellow aptamer company Archemix, NOXXON, a Berlin-based, VC-backed private company holds a license to SELEX (Systematic Evolution of Ligands by EXponential Enrichment), a patented method for generating potent aptamer binders. These companies have reduced to practice the ability to quickly generate aptamers to almost any target. When the targets are circulating proteins, such as MCP-1, there is no need for further chemistry or conjugation to improve delivery.

Delivery improvements

For those targets that are intracellular in nature or otherwise hard to reach, delivery methods are continually improving. For example, in the September, 2009, issue of Nature Biotechnology, there is an exciting paper by Kortylewski et al. reporting successful targeting of tumor cells using an siRNA covalently linked to oligonucleotide agonists for TLR-9 (toll-like receptor 9). These agonists are similar to the CpGs currently in Phase 3 trials of a novel hepatitis B vaccine (Heplisav™) being conducted by Dynavax. The Kortylewski group, led by Hua Yu at the City of Hope Medical Center, achieved potent antitumor immune responses in mice bearing both mouse tumors and human tumors. These results build on earlier findings using antibody-mediated delivery and aptamer-siRNA chimeras. Meantime, most nucleic acid therapeutics companies are pursuing multiple avenues to achieve intraorgan and intracellular delivery of their molecules. To say delivery is a top priority, especially for RNAi companies, would be an understatement.

Meantime, partnering activity continues apace. This week (Tues. Oct. 13) Prosensa, a Netherlands-based, VC-backed private company with an antisense-like molecule to treat Duchenne muscular dystrophy (DMD), signed a deal with GSK for $25 million up front and $655 million in milestones, plus “high double-digit royalties,” according to the GSK press release. The release goes on, “PRO051, the first molecule with this mechanism of action, acts by skipping exon 51 of the dystrophin gene. Mutations in the dystrophin gene result in the absence of normal dystrophin protein, which is necessary for proper muscle cell function.”

Other approaches to treat DMD (for instance gene therapy) have failed, which helps explain why Prosensa’s early data helped the company land such a lucrative partnership. NOXXON already has deals with Pfizer, Roche and Lilly. Many of the other nucleic acid companies in Table 1, most notably Alnylam, have also struck high-value deals with pharma.

In the early days of RNA- and DNA-based therapeutics, company values climbed a “wall of worry” amid speculation that such products would never work. Even the  early clinical success of Macugen and the 2006 acquisition of RNAi drug development company Sirna Therapeutics by Merck & Co. for $1.1 billion did not do much to change the prevalent skepticism. In the meantime, several nucleic-acid-based therapeutics companies trade at healthy valuations and the previous blanket rejection among some skeptics has shifted to a more nuanced analysis. The jury is still out on these advances but the chance of long-term value creation just went up.

# # #

Disclosure: NOXXON has been a consulting client of CBT Advisors. Steve Dickman invested in Sirna Therapeutics when he was a venture capitalist. CBT Advisors has worked for four other companies in the nucleic-acid-based therapeutics field including Alnylam Pharmaceuticals and Sirna Therapeutics.

Table 1: Nucleic-acid based drugs in development (selected). Data courtesy CBT Advisors

Nucleic acid based drug status October 2009

Drug class

Companies

Farthest advanced

Indication(s)

Antisense Isis Market CMV in eye disease
Isis/Genzyme Phase 3 Hypercholesterolemia
Phase 2 Type 2 diabetes
Isis/Oncogenex Phase 2 Mult. cancers
Isis/Atlantic Phase 2 Ulc. colitis/pouchitis
Isis/Teva Phase 2 Multiple sclerosis
Prosensa Preclinical DMD
Aptamers Archemix Phase 2b Thrombotic diseases
Archemix Phase 2 Refractory AML
Archemix/Antisoma Phase 2 Renal Cell Carcinoma
Archemix/Regado Phase 2 Perc. Card. Intervention
Archemix/Regado Phase 3 CABG
Eyetech Market AMD
CpG oligos & TLR agonists/ antagonists Coley Pharma Phase3 (terminated) Hepatitis B (vaccine) adjuvant; oncology adjuvant
Dynavax Phase 3 Hepatitis B (vaccine)
Idera Phase 2 Renal Cell Carcinoma
DNA decoys Avontec Phase 2a Asthma
Avontec Phase 2a Psoriasis
DNA vaccines Inovio Phase 1 HIV
Inovio Phase 1 Cervical cancer
Vical Phase 3 Metastatic melanoma
Vical Phase 2 CMV in transplant
Vical Phase 1 Pandemic flu
Ribozymes RPI Phase 2 (failed) Oncology & others
RNAi drugs Alnylam Phase 2 RSV in infants
Alnylam Phase 1 Liver cancers
Merck/Sirna Undisclosed
MDRNA (fmly Nastech) Preclinical Liver cancers
Opko Phase 3 (terminated) Wet AMD
RXi preclinical Inflammatory disease
Silence/Pfizer/Quark Phase 2 AMD
Silence Phase 1 Acute Kidney Injury
Spiegelmers NOXXON Phase 1 (complete) Diabetic nephropathy

Leave a comment

Filed under Uncategorized