Bruce Booth

Early stage biotech VC. Recovering scientist. Opinions expressed are solely my own and do not express the views or opinions of Atlas Venture.

[Bruce Booth @LifeSciVC]

Excited to have Ethyreal Bio emerge from stealth today!

Ethyreal Bio raises $101 Million in Financing to Advance ETHY-001, a Potentially Best-in-Class Anti-TSHR Antibody for Thyroid Eye Disease and Graves’ Disease

https://t.co/y8LiVKT7ub

[Bruce Booth @LifeSciVC]

With these huge IPOs for SpaceX, Anthropic, and OpenAI… I'm thinking about a couple possible implications for biotech investing:

1/ Many of the large AUM long-only asset management firms (Fidelity, Wellington, T Rowe, Cap Re, etc) are likely participating in a big way in these IPOs.  Given the size of these offerings, these large funds will likely be investing billions into each of these. Every large investor only has so much capital (from a risk management perspective) allocatable to primary offerings of IPOs in a given period… so will these three suck all the oxygen out of the room for long-only firms' ability to play in biotech IPOs in 2H 2026?  Will the sector be even more dependent on specialist healthcare investors for IPOs for the next few quarters?  Seems likely to me.

2/ Right now these three positions are very large private marks on many big investor’s books.  Most of these firms have limits as to what percentage of their AUM can be invested in private deals… when these three move over to the public side, it immediately changes the “ratio”  in a big way… creating significant “space” for private investing in their portfolios.  Will that bode well for their participation in late stage private deals in biotech?  Maybe... hopefully.

So for the next few quarters... while biotech IPOs may be more reliant on specialists, we might see renewed interest from long-only firms in later stage private biotech deals - helping companies stay private for longer.

[Bruce Booth @LifeSciVC]

Arthur Tzianabos' new blog is out... "Biotech’s Most Effective Medicine: No FDA Approval Required"

@ArthurTzianabos #Biotech #NotDietCoke

https://t.co/41Fl6IWYEJ

[Bruce Booth @LifeSciVC]

Reflections on “in-licensing” as the nucleating substrate for NewCo’s in VC-backed Biotech. It’s not new - it's been a tried-and-true component of venture creation for decades - finding great assets and starting companies around them.

~20% of our startups (out of ~50) in the 2002-2014 window (Funds VI-IX) were nucleated with in-licensed assets from Pharma at inception. None of the assets were from Chinese pharma - mostly US/EU/JPN.

~20% of our startups (~70) in the 2018-2026 window (Funds XI-XIV) were similarly nucleated with in-licensed assets at inception. A few of those began with assets from Chinese partners, but also others in US/EU/JPN

Most of what we continue to do is de novo venture creation around great science with talented entrepreneurs and founders.  I suspect other early stage VCs are similar.

[Bruce Booth @LifeSciVC]

Seems like a smart IP policy idea: enabling some version of delayed publication of patent applications. Would help protect novel biotech inventions not only from Chinese competitors, but all the other US/global competitors utilizing tried-and-true pharma industry patent-busting strategies

[Bruce Booth @LifeSciVC]

US Biotech job postings picked up as quarter progressed. 2026 Q1 Job Market Report. @biospace

Interestingly, Boston open positions on their site went up nearly 50% since August.

Slone Partners: the "market looks better than it did a year ago", highlighting "positive hiring discussions with clients"

https://t.co/rS4faTO7RP

[Rod Wong, MD @docrodwong]

a nice longform writeup from bruce booth arguing why it would be a mistake to ban US-china IP licensing.

[Bruce Booth @LifeSciVC]

There is indeed a high vacancy rate in lab space in the Boston market. But this has zero to do with China. It's because the real estate market massively overbuilt in the pandemic bubble... then we a broad market correction.

Biotechs in MA today utilize 14% MORE space than they did pre-pandemic; the sector hasn't shrunk its footprint over the long run.

There's a lag between funding and building... VC funding peaked in 2021, building peaked in 2023... massive over-supply of space - even with real square footage growth in the underlying utilization by biotech

[John Maraganore 🇺🇸🇬🇷🇺🇦 @JMaraganore]

Great analysis by @LifeSciVC!

To me, it’s pretty clear that biotech exists to help bring medicines to patients.

We should keep patients as our Northstar and welcome innovation from anywhere in the world!

[Bruce Booth @LifeSciVC]

https://t.co/bDuiMFRA8N

[Bruce Booth @LifeSciVC]

Patient-first, America-first: The Case For Global Collaboration.
While the rise of Chinese biopharma in the past decade has been meteoric, I’m firmly in the camp that their engagement in the global ecosystem is good for the sector – its more opportunity than threat, great for patients, and is a healthy forcing function to raise the game for everyone
New blog link 👇

[Bruce Booth @LifeSciVC]

Patient-first, America-first: The Case For Global Collaboration

While the rise of Chinese biopharma in the past decade has been meteoric, I’m firmly in the camp that their engagement in the global ecosystem is good for the sector – its more opportunity than threat, great for patients, and is a healthy forcing function to raise the game for everyone

https://t.co/C6mQnRxbt2

[Mario Balsa @MarioBalsaMD]

👑2️⃣ My ASCO Top 10 Pick #2

OBX-115: engineered TILs with regulatable mbIL15 in ICI-refractory advanced melanoma

💥 ORR 67% (2 CRs) || DCR 93% || DoR NR
✅ No DLTs/ICANS/ICU transfers
▪️ No IL-2 required

Small numbers and short follow-up, but this may be one of the most exciting next-generation cell therapy platforms in melanoma!!!

AGNI may just have lit the fire 🔥

Congrats to @DrBetofMDPhD and all the team! AMAZING!! 👏🏼

@OncoAlert

[Bruce Booth @LifeSciVC]

@SamDavisEsq @oakazaki @FlagshipPioneer Moderna's mkt cap is $18B. So I don't understand the datapoint: 11 IPOs from that vintage and $14B in value?

[Bruce Booth @LifeSciVC]

Fun event PSA: any biotech exec's want to go fishing for striped bass in the Boston Harbor?

Capital Advisors Group are sponsoring their 3rd Annual Biotech and Bass Fishing Tournament on Friday June 26th. No cost to attendees... just fish in the morning, then lunch and drinks served at The Barking Crab

Registration: https://t.co/BZE37QJFKk

[Vipin Suri @VipinSuri4]

Early (n=15) OBX-115 (TILs with Acetazolamide regulated membrane bound IL15) Ph2 data in Melanoma/NSCLC looks remarkable: 67% cORR with a CR (and no IL-2 needed!). Here's a mountain sickness drug making T-cells do amazing things. Congrats @Obsidian_Tx https://t.co/BsfI3qbph3

[Bruce Booth @LifeSciVC]

"Year One as CEO: What Leadership Actually Feels Like" - personal reflections from @AbbasRKazimi after a year as CEO of @NimbusTx - latest From The Trenches blog.

https://t.co/RBnmjImoJV

[Bruce Booth @LifeSciVC]

Stay Humble: Life Sciences as a Small Slice of an Increasingly Big Venture Pie.

New data-rich blog from
@AimeeRaleigh13 on the comparative scale of bio sector vs tech

https://t.co/sPIMtuWvWy

[Kymera Therapeutics @KymeraTx]

We’re pleased to share that the FDA has granted Fast Track designation to KT-621, our investigational, first-in-class, oral STAT6 degrader for the treatment of moderate to severe asthma. This designation supports our goal of advancing a novel, once-daily oral medicine with the potential to transform treatment paradigms for millions of patients across multiple Type 2 inflammatory diseases. Learn more in our recent press release: https://t.co/2B4Vw5MMRZ
#RevolutionizingImmunology

[Bruce Booth @LifeSciVC]

"Do One Thing Every Day That Scares You" - debut From The Trenches blog from Linda Bain, serial biotech executive and Venture Partner at Atlas, on pushing yourself to the uncomfortable...

https://t.co/eyXGovi3FX