ENGN is trading at a negative $145M valuation - less than zero.

In this post, I walk through why the Street has completely written off this company, how that is mostly correct for now, but what could turn things around.

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JNap

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I am long ENGN and CGON.

This video walks through IMUX ahead of its topline Phase 3 results from the twin ENSURE-1 and ENSURE-2 studies in relapsing Multiple Sclerosis (rMS), expected in late 2026. The setup seems interesting!

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JNap

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I’m a little bummed because AMLX told us the data was coming in late August/early September, so I thought that when I recorded this podcast on AMLX and VOGX, we’d have at least a week or two to digest it, discuss it, and place appropriate trades.

Well, AMLX just announced data tomorrow at 8 AM. That means AMLX’s fate will be decided tomorrow. But newly public VOGX is just getting started, and I think it’s a very interesting proxy trade that could offer significantly more upside and less downside for investors.

In this podcast, I cover AMLX and VOGX, and why I’m short AMLX and long VOGX going into tomorrow’s data. My position in both is very small.

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JNap

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This ~41 min podcast provides an update on (some of) the Fund’s current holdings, which I categorize into three buckets: Core, Emerging, and Yolo.

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JNap

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Here’s a video walkthrough of my IVA model, with a basic overview of the science, the MASH landscape, the drug, the P2b data, my prediction of the P3 outcome, odds, peak sales, and valuation. It’s ~45 min, so grab your popcorn and watch at 1.5X (lol).

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JNap

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This (long) podcast covers OCUL’s AXPAXLI vs. EYPT’s DURAVYU ahead of the readout of EYPT’s first-phase 3 study called LUGANO.

I provide background on the science, clinical data, endpoints we know (from OCUL’s SOL-1), and endpoints we’re extrapolating based on existing data (to OCUL’s SOL-R and EYPT’s LUGANO/LUCIA studies). I make some predictions and share my assessment of the market. I conclude with thoughts on valuation and how my portfolio is positioned at this time.

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JNap

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Disclosure: We are Long OCUL, Short EYPT

There are three high-profile clinical trial readouts from small-cap biopharams expected in the next few months. Those are:

1) Alumis Inc (ALMS), investigating envudeucitinib for Systemic Lupus Erythematosus (SLE) in the Phase 2b LUMUS trial.
2) Syndax (SNDX), investigating axatilimab for idiopathic pulmonary fibrosis (IPF) in the Phase 2 MAXPIRe trial.
3) Tenax Therapeutics (TENX), investigating TNX-103 (oral levosimendan) for pulmonary hypertension - heart failure with preserved ejection fraction (PH-HFpEF) in the Phase 3 LEVEL-1 trial.

Realistically, these are all toss-ups, but I’m putting the odds of success at 60/40 for all three trials because no one has time for pigs. This podcast covers the drugs, the trials, why I’m at 60/40 for each, peak sales, upside/downside, and how to position each ahead of the data.

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JNap

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This podcast covers some recent portfolio moves, including several names we’ve sold and/or trimmed - and WHY we are doing this.

• IDYA VKTX GPCR PTGX ALMS CELC ORKA OCUL

• CRNX

Plus, 4 names we are eyeballing for adds (either increasing our position or establishing a new one).

• ABVX MLTX VERA QURE

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JNap

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Here’s a quick analysis of LRMR after this morning’s big update.

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JNap

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This LONG (1 hr 5 min) video is a full “teach-in” style DCF of BCRX.

Good luck!

JNap

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Here’s 17 min on ABBV-APGE and what it means for other INI names.

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JNap

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Here’s 13 min of me walking through my valuation on QURE after this morning’s news that there seems to be a line of sight to both U.S. and EU/UK approval in 2027.

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JNap

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Thanks to everyone who submitted questions for this week’s (free) podcast! I’m sorry I didn't get to all of them, but if you guys think this went well, I’m happy to do more “Q&A” podcasts in the future!

Stock discussed (in order): MLYS, RCKT, NGNE, NRIX, OTLK, RNTX, TNGX/RVMD, and IDYA. I also sprinkle in some of my trading philosophy and rules.

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JNap

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Please see all my disclaimers & disclosures on Bio5C.com

This ~40 min podcast provides 10 min of thoughts on (in order) ABVX, CELC, and MLYS, and then concludes with 10 min on a few other names that I find attractive right now.

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JNap

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Here are my thoughts on what REPL is worth right now (odds-adjusted)

and what it could be worth if RP1 does get approved later this year.

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JNap

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This Pod covers ~20 or so “Top Ideas” based on the 5C Rank.

If you’re a Bio5C Subscriber, you can view the full 5C Rank » HERE

Tickers covered in this Podcast include (generally in order):

NKTR, RNTX, CRNX, IVVD, ORKA/SYRE/APGE, GPCR, TENX, PHVS, PTGX, RMVD, ABVX, RLAY, CCCC, MLYS, CELC/RLAY, IDYA, SABS, ALMS, NGNE.

This Podcast is ~60 min long - Good Luck!

Special Offer to “Substack Only” Subscribers - If you’re interested in upgrading to a Full Bio5C membership, which includes the Substack, I’ll credit back to you the total amount you’ve paid via Substack towards a 1 Year Bio5C Subscription. That includes all my research and models, the 5C Rank, full access to my Discord, and one round of golf with me, at my local course (includes a hot dog at the turn). DM me for details!

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JNap

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I really like PHVS. This video walks you through my model on the company.

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JNap

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Neurogene Inc. (NGNE) is one of the most compelling investment ideas I have at this time. The company is developing a disease-modifying gene therapy for the treatment of Rett Syndrome. NGN-401, because it targets the root cause of the disease, has already shown multi-domain developmental gains that are highly unlikely under natural history, and appears well-positioned to not only gain approval but capture sizable market share among the Rett population, despite investors’ perceived disadvantages on safety and delivery compared to Neurogen’s top competitor in the space, Taysha (TSHA). ​

The current Rett market remains meaningfully underserved. Acadia’s (ACAD) Daybue is an important first product, but clinicians continue to describe its benefit as modest and constrained by gastrointestinal tolerability issues, frequent underdosing, and high real-world discontinuation rates. In contrast, both NGN-401 and Taysha’s TSHA-102 are viewed as potentially disease-modifying, with adoption ultimately expected to be driven by meaningful gains in communication, hand function, ambulation, durability, and overall caregiver burden. ​

Neurogene does not yet have a clean efficacy lead over Taysha in the eyes of clinicians. However, the company does appear to have several underappreciated strengths: a full-length MECP2 construct, a differentiated EXACT regulation system, increasing clinical evidence of deepening multi-domain benefit over time, a registrational design aligned to current U.S. FDA expectations - a recent FDA-issued Breakthrough Therapy designation - a massive market opportunity that absolutely will support more than one winner - but importantly, it trades at less than one-quarter of Taysha. And that just does not make sense.

Let’s get into why!

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Background on Rett

Rett syndrome is a severe neurodevelopmental disorder that typically affects girls after an initial period of apparently normal early development, followed by developmental delay and then regression. Hallmark features include loss of purposeful hand use, loss of verbal language, stereotyped hand movements, impaired ambulation, and a broad set of medical comorbidities that accumulate over time. ​

The disease burden extends far beyond the core neurologic phenotype. KOLs describe Rett patients as often nonverbal, medically complex, and living well into adulthood, frequently with epilepsy, constipation, reflux, feeding issues, scoliosis, sleep dysfunction, orthopedic problems, and varying degrees of gait impairment. The most burdensome issues for families are communication, hand function, ambulation, seizures, and constipation.

This matters commercially because Rett is not a rapidly fatal, short-duration opportunity. It is a chronic, lifelong condition with long survivorship and substantial caregiver burden, which supports a durable prevalent pool and makes clinically meaningful functional (developmental) gains valuable to families, physicians, caregivers, and, importantly, payers.

Existing option: Daybue

Acadia’s Daybue (trofinetide) is an oral, twice-daily, small-molecule synthetic analog of glycine-proline-glutamate (GPE), the N-terminal tripeptide of IGF-1. Daybue is the first approved therapy for Rett syndrome, but it is generally viewed as a symptomatic treatment rather than a disease-modifying. Clinicians describe its real-world benefits as improvements in alertness, engagement, and interest in communication devices, with less consistent impact on the core deficits of hand function, ambulation, and language.

Its main weakness is tolerability. KOLs report that many patients remain at roughly 60–80% of the target dose (24 g/day), that few complete titration, and that diarrhea, vomiting, feeding burden, and caregiver disruption are major reasons for discontinuation. Even more optimistic prescribers still characterize the effect size as small. ​

That leaves a large therapeutic gap. Daybue has validated Rett as a treatable commercial market, but it has not solved the disease in a way that would prevent uptake of a one-time therapy capable of producing durable milestone gains in hand use, gross motor function, and communication.

Gene therapies: TSHA vs NGNE

Both NGN-401 and TSHA-102 are viewed by clinicians as more exciting than Daybue because they aim to address the underlying MECP2 biology rather than merely modulate symptoms. In clinical studies, both have produced developmental milestone gains that are highly unusual in untreated Rett patients, and both are currently viewed by KOLs as broadly comparable in efficacy and safety at their respective doses.

Both NGN-401 and TSHA-102 are AAV9 gene therapies. That said, I believe that Neurogene’s approach has several strategic advantages. NGN-401 delivers full-length MECP2 using the company’s EXACT regulation system, whereas Taysha uses a miniMECP2 construct with a different miRNA-based regulatory strategy. KOLs see trade-offs between the two approaches, but a full-length MECP2 better aligns with Neurogene’s biology-first thesis and may prove advantageous if preserving the native functional architecture of MeCP2 matters clinically over time. ​

Neurogene also deliberately chose intracerebroventricular (ICV) delivery to maximize brain exposure. While investors often assume this is a major commercial negative relative to Taysha’s lumbar intrathecal (IT) route, recent KOL work suggests the issue is overstated. Physicians report that families are generally comfortable with one-time neurosurgical procedures; some even prefer an approach seen as “closer to the brain” with superior CNS delivery. Simply put, the route of administration is not expected to adversely affect NGN-401. In fact, it might be a competitive advantage.

The most balanced current view is that NGNE does not yet have a proven efficacy edge over TSHA, but it no longer appears to be handicapped as skeptics often frame the story. If the products are clinically comparable today, then Neurogene’s differentiated construct, platform value, in-house R&D and manufacturing capabilities, and potential for stronger long-term differentiation present tremendous upside for investors.

Why NGNE’s approach is attractive

The first reason to like NGNE is its biological design. NGN-401 is built around full-length MECP2 plus EXACT, a regulated-expression system specifically intended to manage the narrow therapeutic window that has historically made MECP2 replacement difficult. This is a more ambitious construct than a truncated mini-gene approach and supports the argument that Neurogene is optimizing for the best possible biology, not just for packaging efficiency.

The second reason is the nature of the clinical effect seen so far. Neurogene has described clinically meaningful, deepening, and durable gains across hand function, gross motor function, communication, and autonomic domains, with milestone accumulation continuing over time rather than plateauing quickly. KOLs consistently emphasize that this kind of multi-domain improvement is exactly what would make them view a therapy as genuinely disease-modifying.

The third reason is strategic positioning beyond Rett. Unlike a pure single-asset story, Neurogene also owns a broader platform centered on regulated CNS gene therapy and maintains internal GMP manufacturing capabilities, creating optionality if NGN-401 succeeds and resilience even if Rett becomes a multi-player market.

Investors can acquire all of this for less than one-quarter of Taysha’s value, which has both outsourced manufacturing and in-licensed IP.

Where NGNE is now

Neurogene is conducting the EMBOLDEN registrational study of NGN-401 in 20 females with classic Rett syndrome, aged 3 years or older, who have entered the disease’s regression phase. The primary endpoint is a composite of CGI-I improvement and a gain of at least 1 developmental milestone from a pre-specified list of 28 milestones at 12 months. ​EMBOLDEN will be successful if 35% of patients (> 7 of 20) achieve the composite endpoint.

The current bull case for Embolden starts with the Phase 1/2 dataset. Neurogene has reported clinically meaningful, deepening, and durable improvements across the key Rett domains of hand function, gross motor function, and communication, with 35 developmental milestones gained among the first 8 pediatric participants and benefits persisting for up to 24 months of follow-up. The company has also reported that 88% of participants achieved an improved CGI-I score and that 100% showed functional improvement in at least one core domain.

Additionally, Neurogene has emphasized that the same 1×10¹⁵ vg dose used in the Phase 1/2, along with the same immunosuppression regimen, taking place at the same Rett Centers of Excellence, standardized using the same CGI-I training, and the same video-based blinded central review framework, are all part of EMBOLDEN. Neurogene has also stated that the trial design was aligned with the FDA after renewed discussions under the current regulatory environment, including acceptance of a 12-month primary endpoint for the registrational path.

Repeat: In the Phase 1/2 study, which mirrors the EMBOLDEN, NGN-401 delivered 88%. EMBOLDEN will be successful at anything over 35%.

The company has guided to the completion of enrollment and dosing in the next few months. Data are expected in the first half of 2027. NGN-401 has a Breakthrough Therapy designation and is part of the FDA’s START program. This positioned Embolden as the primary basis for approval and a broad label by the end of 2027.

Misconceptions: safety, dosing, and relative value

One common misconception is that NGNE’s safety profile is structurally worse than TSHA’s. The main basis for that view is the fatal hyperinflammatory event at the 3×10¹⁵ vg dose. However, clinicians and KOLs generally interpret that event as a dose-dependent AAV9 immune toxicity rather than a unique flaw of NGN-401, and they do not currently see a meaningful safety distinction between NGN-401 and TSHA-102 at the lower doses now being advanced.

A second misconception is that ICV delivery will meaningfully limit demand. The latest KOL work argues the opposite: route is not a major barrier, patient preference is not strongly negative, and some families actually intuitively favor delivery that feels more direct to the brain. Access and site infrastructure matter, but those are commercialization questions rather than proof of weak demand. ​

A third misconception is that NGNE must clearly beat TSHA to create equity value. The Rett opportunity likely supports more than one gene therapy; adoption is expected to be gradual rather than winner-take-all, and both clinicians and Neurogene management describe a market in which families will prioritize durable functional benefit over launch order alone. That setup gives NGNE room to work even if the field remains competitive.

Market opportunity

Rett syndrome represents an unusually attractive rare-disease market because it combines a clearly defined monogenic biology with a meaningful prevalent population and long disease duration. Neurogene and Taysha both frame the addressable population in major markets at roughly 15,000–20,000 patients, with meaningful annual incidence (1/10,000 female live births = 175 new cases each year) and substantial caregiver burden.

Commercially, the key point is not simply prevalence but intensity of unmet need. Families care deeply about improvements in communication, hand use, mobility, feeding independence, and overall daily living burden. A one-time therapy that reliably produces visible gains in those areas should command serious payer attention, especially in a market already validated by Daybue and already familiar to specialist centers.

Adoption is likely to be gradual, initially skewed toward younger and more severely affected patients, but that does not weaken the investment case. Slow uptake actually reduces the importance of a winner-take-all framing and supports the view that multiple products can coexist, while long-term durability and magnitude of benefit determine eventual share.

Valuation

According to both TSHA and NGNE, there are an estimated 15,000 to 20,000 females with Rett syndrome living in the U.S., EU, and UK. I estimate approximately (conservatively) 20% of these are between the ages of 3 and 12 years old and might be candidates for gene therapy. That’s a 3,000-patient TAM. Using Zolgensma’s $2.5 million price tag for SMA as a proxy, I estimate a $7.5 billion TAM that Neurogene and Taysha could share equally. Even if you assumed Neurogene could only capture 1/3rd of the market, that’s still $2.5 billion in cumulative sales. My DCF model suggests an NPV for the stock in excess of $1 billion, excluding existing cash on hand or any value for a priority review voucher (PRV).

The current enterprise value is less than $250 million.

Conclusion

The most defensible bullish view on Neurogene is not that NGN-401 is superior to Taysha. I’m not arguing that. The stronger view is that the market continues to underrate how viable NGNE is as a serious Rett player, despite having already neutralized several bear arguments around route of administration, safety, and FDA/EMA “alphabet soup” designations (NGN-401 has Breakthrough Therapy, RMAT in the USA, PRIME in the EU, and is part of the FDA’s START Program).

Daybue has validated the unmet need but also shown the limitations of symptomatic therapy. TSHA remains a credible competitor. Yet Neurogene still stands out because it combines full-length MECP2 biology, a differentiated regulation platform, encouraging multi-domain clinical data, a sensible current dose, a registrational program aligned with current FDA expectations, in-house manufacturing, and a CEO who seems highly credible. Finally, the market absolutely accommodates more than one winner.

For investors, the core question is no longer whether NGNE is disqualified by ICV or by a permanent safety overhang. The better question is whether the company can convert a now-credible clinical and regulatory position into a durable efficacy story that becomes distinguishable over time. Based on the evidence available today, maintaining a constructive bias on NGNE remains justified, and increasing conviction can be rational if one believes durability and breadth of effect will continue to strengthen with follow-up.

I am long NGNE. My model pegs the fair value at $65/share.

Cheers,

JNap

Sources:

1. Daybue PI - Acadia Pharmaceuticals

2. Leerink Partners: Rett Syndrome MEDACorp Pulse Call - April 2026

3. Neurogene Inc - JPMorgan Conference Call Transcript - January 2026

4. Slingshot Insights - KOL Call Transcript - March 2026

5. Rett Syndrome - NCBI-NLM - September 2025

6. Rett Syndrome - Nature Genetics - 1999

7. Taysha Corp Presentations - January 2026

8. TAY-57602 CNS 2025 Poster - Taysha Website 2025

9. Taysha May 2025 Investor Update Slide Deck - May 2025

10. Neurogene - BPNA NGN-401 Interim Update - 2024

11. Neurogene ESGCT 2025 Poster - Neurogene Website 2025

12. Neurogene Corp Presentations - January 2026

13. Neurogene Press Release on Breakthrough Therapy - February 2026

14. Slingshot Insights TSHA/NGNE/ACAD KOL Call - July 2025

15. TSHA Form 10K - Year End 2025 (March 2026)

16. NGNE Form 10K - Year End 2025 (March 2026)

17. Neurogene Fireside Chat - Stifel Conference - March 2026

18. Neurogene Fireside Chat - Leerink Conference - March 2026

19. Neurogene Fireside Chat - TD Cowen Conference - March 2026

20. Neurogene Fireside Chat - Guggenheim Conference - February 2026

21. Neurogene Research Report - Leerink Partners - March 2026

22. Neurogene Research Report - TD Cowen - March 2026

23. Neurogene Research Report - HC Wainwright - February 2026

24. Perplexity Pro - Used to summarize and consolidate opinions from many of the above reports, papers, posters, slide decks, and links.

25. Bio5C.com/ngne

26. Bio5C.com/tsha

Last week, RNTX raised $50M to push LTI-03 forward in a Phase 2 study called RENEW. I find the drug mechanistically interesting, with net directionally positive Phase 1b and preclinical data. The Phase 2 RENEW study carries significant risk, with the odds of success at this stage likely still below 50%. But the $50M financing is signaling something, and I think there are a few ways investors can win here.

My podcast covers the financing, the preclinical data, the Phase 1b data, the market opportunity, and why I think RNTX is attractive here at $1.03/sh - just 3 pennies above where the $50M financing took place last week.

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JNap

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This podcast covers:

• Chiesi’s acquisition of KALV and why it makes me more bullish on PHVS.

• Why I still like PTGX

• What I thought of the ERAS data and why I’m even more bullish on RVMD.

  I posted my valuation model for RVMD below.

• The ORKA data, and maybe what’s hitting ABVX lately?

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JNap

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