Prime Dramas

$prme (must read) No Nonsense: David Liu Lauds Progress in Disease-Agnostic Gene Editing at ESGCT genengnews.com/topics/genome…

FDA published draft guidance yesterday that could change how genetic medicines reach rare disease patients. The problem it aims to solve: a single genetic disease is often caused by many different mutations in the same gene. Until now, a therapy tailored to each mutation risked needing its own approval process. For diseases where a mutation might affect a handful of people; patients and families continue to wait. This new framework could enable a company to get one approval for a disease, with the boundaries of what can be customized defined up front. Once approved, the version for the next patient’s mutation could be added as a supplement if supported by in vitro data: evidence in cells that the new version edits the target efficiently and stays within the off-target limits set during the original clinical program. In most cases, no new clinical data would be required. One product, one name, and a clear path from the first patient to the next.  This could be a promising way to unlock many opportunities, especially in rare and ultra-rare diseases, a win for patients, their caregivers and for our industry. Prime editing was designed for it: one platform, one delivery system, and only a small patient-matched component change. We appreciate the FDA / CBER teams for the forward thinking and patient focus. We look forward to working together on this guidance. Let’s get more medicines to more patients in need. Draft guidance: fda.gov/media/195887/downloa…

To take full advantage of this pathway, a company must be able to produce variant-specific gene editor doses efficiently for patient populations with specific variants Beam’s internal, vertically-integrated manufacturing capability enables exactly that: teapawt.net/john_evans3/status/211…

First, the FDA released new draft guidance on the BLA approval pathway for gene editing products covering gene editors for multiple variants: fda.gov/media/195887/downloa…

Exciting updates on gene editing support from the U.S. Government! We didn’t plan this… but just a few hours after our conference call outlining Beam’s vision to deliver increasingly customized genetic correction therapies to patients, even more news hit

Surprise 1: Anthropic acquired a one-person biotech . . . Surprise 2: that person is me Surprise 3: I’m here to tell you all about it Yes, this is what you think it is; after 6 yrs of increasingly loose anonymity: the Professor Oak reveal post …and yes, it has gotten so boring around here that I’m literally doxxing myself to spice up the timeline ------- Ok, allow me to introduce myself. My name is Cody Tranbarger. I mostly tweet, but occasionally find time to dabble in drug dev & starting/building biotechs. My past lives span the VC, crossover, startup continuum; Prof Oak has been my way of keeping a digital foot in those worlds, despite having my physical feet planted elsewhere. The past 18 mo, ‘elsewhere’ was Mithril Medicine, a co. I founded to develop bsAbs for LAMA2-CMD & other ECM-related genetic diseases. Mithril was born out of hands-on building with @MikeNGladstone, @JasonPaulRhodes, @LifeSciVC, & team @atlasventure. Somehow, I made enough half-decent calls along the way (even a broken clock is right twice a day, eh?) to convince them Mithril/I warranted a small seed. While I can hardly rationalize such an outrageously cavalier bet, I’m grateful for it, & I'd partner with Atlas again in a heartbeat. In typical AV fashion, Mithril’s primordial form was virtual, decentralized, & ultra-lean. This stage tends to be short-lived, but for Mithril, it worked surprisingly well, for surprisingly long, thanks in part to the rapid maturation of the AI tools I used liberally. Eventually, Mithril became a bit of an experiment itself - to find the upper bound of how far it could scale as a single operator + a bunch of Claude (+ a stellar bench of part-time consultants). In parallel, I started spending time with @nc_frey, @an1lam, & @CoefficientBio team; and promptly experienced, for the 1st time, AI at the frontier. Soon thereafter, Mithril stopped looking like an experiment, & started looking like a preview of an entirely new operating model. From that spark came “Pipeline-in-a-Person.” The idea immediately resonated when we shared it here back in April; and it was central to the shared vision that led to Anthropic’s acquisition of Mithril, & my joining the team. Why join Anthropic? Three reasons. (1) For Mithril, the programs continue, with more resources & infrastructure behind them, and as much Claude as I can put to work. (2) For me, the chance to start several more programs, & find out how many one person can actually run in parallel - an almost unprecedented luxury for a curious drug hunter. (3) For our mission, a path to institutionalize & scale this new way of working, then put it in the hands of all of biopharma, all over the world - which, candidly, I find the most energizing. Will AI x Bio cure diseases? Unequivocally yes, imo… but not by the route that gets the most airtime. Rather than timeline acceleration & compression, I see orchestration & parallelization as today's low-hanging fruit. Most drug hunters see a handful of go/no-go calls in a career, & spend entirely too much of the rest trading emails (my inbox can attest). Give them the bandwidth to run several programs at once, and the time to focus on scientific judgment, and I’m willing to bet they’ll make better calls. And at scale, better calls translate to more drugs, higher hit rates, broader patient impact, & likely, a disease or 10 or 100 cured. I couldn't be more excited to build toward that future @AnthropicAI. Finally, a heartfelt thank you to BioTwitter/X. The end of anonymity is bittersweet, but if anyone’s earned a proper introduction, you all have. It’s difficult to overstate how much this app has done for me: a decade of education, plenty of friends, many job opportunities, several mentors, a few investors, even a co-founder (fmr). It was the generosity of this community that inspired me to start posting 6 years ago, after just as many years lurking. I hope I’ve been able to pay it forward, in my own small way. But, to be clear, Prof Oak isn’t going anywhere. Same beat, same themes, and now, a front-row seat to drug development at the frontier. Stay tuned for dispatches from the trenches; and remember... Gotta Cure 'Em All

$PRME This guidance seems tailored to Prime's modular platform, even mentions "reverse transcriptase-based editors" twice 👀 Here are 4 key insights and why this could be a massive catalyst for Prime: 1) One BLA Across Mutational Families CBER's new blueprint outlines how companies can bundle multiple mutation-specific product variants for a single gene under one BLA, brand name, and NDC. Under the guidance, sponsors can establish an "Individualized Feature Space" (IFS). The core drug components (like the LNP delivery vehicle, formulation, and editor engine) stay fixed, while the guide sequences vary to address different patient mutations. • Instead of filing separate, costly BLAs for every individual mutation in a disease, the FDA would legally consider these variants to share the same active ingredient. • All variants could share a single brand name, prescribing label, and NDC (National Drug Code), with the container label simply specifying the targeted gene variant. 2) Adding New Mutations Post-Approval via In Vitro Data Alone Once an initial IFS is approved with clinical proof-of-concept, sponsors wouldn't need to run new clinical trials to add unstudied variants. • Under an approved Postapproval Change Management Protocol (PACMP), new mutation-specific guides could be added through streamlined CMC manufacturing supplements using in vitro potency and NGS off-target safety assays. • These in vitro safety packages could even be generated using scaled-down, representative material rather than full commercial batches. 3) Custom CMC and Process Validation (PPQ) Relief Prime editing pegRNAs vary in length and secondary structure depending on the mutation, which traditionally created major manufacturing validation headaches. • CBER explicitly addresses this, instructing sponsors to design flexible chromatography and mixing controls upfront rather than revalidating the process for every sequence. • Even better, the FDA removes the requirement to run Process Performance Qualification (PPQ) campaigns on every variant. Sponsors could bracket manufacturing scales instead. For Prime, managing a $108.8M cash balance as of Q2, avoiding redundant clinical trials and validation campaigns would preserve critical runway. 4) Commercial Blueprint for Wilson Disease and Beyond As mentioned, CBER explicitly cites "reverse transcriptase-based editors" (part of Prime's editing platform) in the text when defining "platform" boundaries. • In Wilson disease, Prime's lead in vivo asset (PM577a) targets the western H1069Q mutation, while a follow-on candidate targets the East Asian R778L mutation. Prime could clinically validate both under a shared ATP7B IFS, secure a single BLA, and then systematically roll out pegRNAs for the long tail of rare ATP7B mutations using in vitro data to capture the entire global market. • The exact same playbook applies to Prime's cystic fibrosis program (covering non-modulator CFTR mutations), PM647 in AATD (expanding from PiZ to rare SERPINA1 variants), and ex vivo CGD. Why is this all important? A major bear thesis on mutation-specific gene editing has always been commercial fragmentation. If a therapy only fixes one specific spelling mistake, how do you affordably treat the hundreds of other mutations in the same gene? This new draft guidance directly answers that question. Keep in mind that this framework applies to multiple mutations within a single target gene, so PM577a (Wilson) and PM647 (AATD) will still require separate BLAs despite sharing the same Universal Liver LNP. In summary, this draft guidance provides the exact regulatory bridge Prime would need to overcome mutation fragmentation and allow them to turn bespoke single-mutation fixes into scalable, single-license commercial franchises without having to fund standalone clinical trials for every variant.

Glad to be at the @RareDiseases Summit for some Breaking News.This morning I attended the Rare Disease Regulatory Roundtable, moderated by @ComstockRi54463 Assoc. Director of the FDA rare disease hub. Guest speaker #karimMikhail made an announcement about individual gene therapy. He is Director of CBER. Watch it here! Very exciting! @FDA @DCOfficial #science #innovation

🚨CURIOSIDADE: Bolo de aniversário de Maria Flor pesa uma tonelada, tem mais de 3 metros de altura e custou pelo menos R$ 250 mil.

IMO… it is a mistake to “try to increase U.S. competitiveness through protectionism.” The new rule “may make it easier for non-U.S. companies to succeed through manufacturing in China. This wouldn’t help our global competitiveness.” IMO… let’s instead kick ass with American ingenuity! biocentury.com/article/66129…

Big News! CDER's Accelerating Rare disease Cures (ARC) Program released its 2026 Annual Report, highlighting the Program’s success in advancing rare disease drug development for the ~30M Americans living with a rare disease. Read it here: fda.gov/drugs/drug-alerts-an…

Reminder: FDA is holding a hybrid meeting on Oct. 28 from 1-5 pm ET to seek input on its Rare Disease Framework Initiative reimagining the agency’s approach to rare disease drug development. Find out how to register: fda.gov/news-events/fda-meet…