Reactorfield @ReactorfieldAI

Come meet these amazing fellows at our demo day: SF October 1st! luma.com/jeuh0xqp

If you want to participate in Cohort 2, applications are open today! reactorfield.com/apply

Xilio Therapeutics (@xiliotx) is a clinical-stage immuno-oncology company engineering cancer therapies to activate chiefly inside tumor microenvironments. Publicly traded on Nasdaq (XLO), Xilio has raised over $200M to date. In August 2026, the FDA cleared its IND for XTX501 as a potential foundational backbone therapy for solid tumors, with a Phase 1/2 trial starting in the second half of 2026.

x.com/jamessinka/sta… Cohort 1 represents top talent from industries including mRNA, brain-computer interfaces, longevity, nuclear fusion, and beyond. This exceptional group uses AI to accelerate their scientific R&D, and make the world a better place. Deep dive below 🧵:

James Sinka - Boston & SF @jamessinka

3 weeks ago

Excited to introduce @ReactorfieldAI Cohort 1: @merge - brain-computer interfaces with no implants, $250M seed led by OpenAI and Bain @episteme - a new R&D institution, cofounded by Louis Andre and Sam Altman @RetroBio_ - unicorn longevity startup, adding 10 healthy years to

26 57 219 27K 99

Strand Therapeutics (@StrandTx) is an MIT spinout building programmable mRNA medicines. Its total funding exceeds $250 million, including Regeneron Ventures, ICONIQ, Amgen Ventures, the family office of former J&J CEO Alex Gorsky, and Eli Lilly. The company combines targeted lipid nanoparticles, microRNA-responsive safety circuits, and self-replicating or circular RNA to address mRNA's central challenges of targeting, safety, and durability. Its lead IL-12 program, presented at the 2025 ASCO Annual Meeting, has shown early clinical activity in advanced solid tumors.

Retro Biosciences (@RetroBio_) is a clinical-stage longevity company aiming to add ten healthy years to human life. Backed with a $180 million check from Sam Altman in 2022, it has since raised at a reported $1.8 billion valuation. Its lead oral program, RTR242, is designed to restore autophagy and entered Phase I testing in Austria in 2025.

Radify Metals (@radifymetals) is rebuilding a critical-minerals supply chain through the conversion of metal oxides into high-purity metal. The company has raised just under $3 million from Overture, Founders Inc., Mana Ventures, and Acequia Capital. Its modular hydrogen-plasma reactors transform rare-earth and other critical-mineral oxides directly into metal. Radify is building a flexible domestic metallization platform that could make critical-metal production faster, cleaner, and more resilient, directly targeting a supply chain in which China currently controls roughly 87% of global rare-earth refining capacity.

Dr. Brian S. Kim, MD (@itchdoctor), is Northwell Health’s Chief Biotech Officer. Northwell Health (@NorthwellHealth) is New York's largest health system and employer, serving over 3M patients annually. Brian contributed to two FDA-approved treatments, authored more than 190 publications, holds multiple patents, and co-founded three biotech companies. He has been continuously funded by the NIH since 2011.

Merge Labs (@merge) is a research lab building higher bandwidth, less-invasive brain-computer interfaces that connect with neurons using molecules instead of electrodes, transmit and receive information using deep-reaching modalities like ultrasound, while avoiding implants into brain tissue. Merge Labs was co-founded by leading BCI researchers, Sam Altman, Alex Blania, and Sandro Herbig. OpenAI and Bain Capital led Merge's $250M seed round which also included investments from Interface Fund, Fifty Years, and Valve co-founder Gabe Newell.

Vera Mucaj (@vera_mucaj), PhD, is an EIR at Mayo Clinic (@MayoClinic), where she helps turn leading clinical science into new ventures. Previously, Vera was Datavant’s Chief Scientific Officer and employee #8. She led the life sciences product portfolio and founded the clinical trials business, which was adopted in over 250 trials by most top 20 pharma and biotech companies.

Mass Magnetics (@MassMagnetics) is a YC-backed startup building high-performance permanent magnets domestically from recycled rare-earths. The founders previously built battery pilot-production lines and materials-science labs for NASA, Draper Labs, and MIT.

Marathon Fusion (@MarathonFusion) produces the world’s most valuable isotopes with compact, commercial fusion reactors. Founded by a team from SpaceX, Schmidt Futures and Princeton, Marathon is supported by $18m in funding and revenue across the US Department of Energy, the UK Atomic Energy Authority, and leading private investors. Company calculations show that power plants using its approach could generate roughly 5,000 kg of gold per year per gigawatt of output.

Lume Health (@lumehealth) is building a continuous hormone-monitoring wearable: a wrist-worn, sweat-sensing platform built on a proprietary aptamer biosensor, starting with cortisol. The company was founded by Vicki Powell, a former Apple sensor engineer who holds three wearable sensor patents, and Jonathan Moustakis, MD, a nationally recognized physician-researcher. Lume has raised $2.5 million to date.

Kopra Bio (@KopraBio) is a YC-backed oncology company developing viral immunotherapies that turn cancer cells into local factories for their own destruction. The UCSF spinout closed a $9.1M seed co-led by Boutique Venture Partners. Its first focus is glioblastoma, one of the most lethal and immunologically resistant cancers. In preclinical mouse models, Kopra pushed survival rates from 0% in controls to 90% in treated animals, with durable remissions and immunologic memory. Kopra is translating that viral-immunology foundation into a new approach to solid tumors.

Kathy Liu (@liu_liu_lemon) is a @Harvard PhD student and previous Fulbright Research Fellow designing smart materials for med tech, swarm robotics, tactile sensing, and bio-interfacing electronics.

Foundation Industries (@FoundationManf) is modernizing the way frontier-hardware teams get parts made. The YC-backed manufacturer delivers rapid domestic CNC machining, including two-day turnaround, through a software-native workflow connecting CAD upload, specifications, quoting, payment, and production tracking. They will serve in the long term as the physical world API for the frontier.

Episteme (@episteme) is a new R&D institution, founded by Louis Andre and backed by Sam Altman and SoftBank's Masayoshi Son. It brings exceptional researchers, long-horizon funding, and operating infrastructure under one roof to pursue high-impact work across physics, biology, neuroscience, and engineering, modeled on Bell Labs and Xerox PARC. The team includes veterans of the Gates Foundation, DeepMind, and government ARPA agencies.

Alga Biosciences (@algabiosciences) is turning enteric methane into calories for livestock. The YC-backed company has raised roughly $8M and was awarded a USDA Climate Smart Commodities grant. In controlled cattle trials, its Alga 1.0 formulation showed peer-reviewed methane-yield reductions of 39% and 63% at the studied inclusion rates.

Choosing between Claude and GPT for a biology task starts with knowing where each fails. @LatchBio builds benchmarks that test AI agents on real biological data, making those failure modes visible so scientists can make more informed choices about models and prompts. Arjun Banerjee (@arjunomics) is joining Reactorfield for a hands-on introduction to benchmarking for scientists: when you need one, how to build your first, and how to test whether a change to your workflow actually improves results.

Scientific workflows often involve unpublished results, proprietary methods, and sensitive data. @getopenwork lets teams build AI workflows with self-hosted open-source models on infrastructure they control. They can then share AI skills and tool connections across the lab, so colleagues can reuse those workflows. Ben Shafii (@benjaminshafii ), founder of OpenWork, is joining Reactorfield to explore how scientists and deep tech teams can bring AI agents into everyday research, with a focus on handling confidential data and building workflows the whole team can use.