Xaira Therapeutics

$1B+ AI biotech co-founded by David Baker: de novo antibody design plus a Perturb-seq "virtual cell" data factory; pipeline still early.

1. Core Product / Service

Xaira launched in April 2024 with more than $1B in committed capital, incubated by ARCH Venture Partners and Foresite Capital [1]. It combines three model families [2][3]:

X-Design — generative antibody/protein design building on the RFdiffusion / RFantibody lineage from david-baker's Institute for Protein Design; the CEO describes the goal as antibodies that are "drug-ready" from the start [2].
X-Cell — a ~4.9B-parameter ai-virtual-cell model (March 2026) that predicts transcriptional responses to genetic perturbations [3].
X-Patient — patient-response modeling [2].

The data engine is in-house single-cell perturbation screening (FiCS Perturb-seq on 10x Chromium): X-Atlas/Orion (June 2025, ~8M cells, genome-wide CRISPRi, released publicly) and X-Atlas/Pisces (March 2026, ~25.6M cells across 7 screens / 16 contexts), which trains X-Cell [3][4]. Pipeline: Xaira has disclosed two early programs, XA-1 and XA-4, without naming targets; no IND or clinical program has been announced [2].

Wet lab:

Item	Detail
South San Francisco	700 Gateway Blvd; expanded from 56,233 sf to 73,075 sf in Dec 2024 (lab/office split undisclosed) [5]
Seattle	Lab near Lake Union led by former IPD scientists; size not disclosed
London	Likely office / compute only (inferred from facilities job posting)
Headcount	~193 (third-party estimate, March 2026); roughly half estimated to be wet-lab
In-house	Perturb-seq / NGS genomic core, protein sciences, a robotic lab-automation build-out (hiring signals)
Outsourced	No named CRO/CMO; an SVP for translational science and early development joined in July 2026, implying IND-enabling work ahead

2. Target Users & Pain Points

Its own pipeline first; a SVP for business development and AI drug-discovery partnerships (Rachel Lane) was appointed in March 2026, signalling openness to pharma deals [6].
Pain addressed: antibody discovery by immunization/screening is slow and target-limited; virtual-cell models aim to pick targets and predict response before costly experiments.

3. Competitive Landscape

Player	Approach	Vs. Xaira
generate-biomedicines	Generative protein design, Phase 3 antibody	Years ahead clinically
chai-discovery / nabla-bio	De novo antibody models, partner-funded	Sell or partner the platform; Xaira keeps assets
isomorphic-labs	AlphaFold-lineage, small molecules	Comparable capital, different modality
lila-sciences	"Scientific superintelligence" + AI Science Factory (~244k sf)	Broader scope and ~3x the lab footprint
genbio-ai / Arc Institute	Virtual-cell foundation models	Overlap on X-Cell; Xaira generates its own perturbation data

4. Unique Observations

Lab as data factory, not as CRO substitute: Xaira is the only company in its peer set that has published auditable throughput numbers (~34M perturbed cells across two datasets); other private AI biotechs disclose only company-phrased claims [4][5].
$1B does not buy a campus: even with the largest launch round in the cohort, Xaira's main lab is ~73k sf — one part of a single South SF building, similar to newlimit or Enveda, far below lila-sciences [5].
Valuation anchored to a pipeline that is not yet visible: two years after launch only XA-1 / XA-4 are named, without targets [2]. The investment case still rests on the platform and team.

5. Financials / Funding

Launch (April 2024): >$1B committed capital, ARCH and Foresite co-leading [1].
Unresolved figures: an "$800M Series A", "~$1.3B cumulative" and valuations of $2.7B/$3.5B circulate on aggregator sites only and are not confirmed by the company or primary press [6]. Treat anything beyond ">$1B committed" as unverified.
Revenue: none disclosed.

6. People & Relationships

CEO: Marc Tessier-Lavigne (former Stanford president; former Genentech research head) [1].
Co-founder: david-baker (2024 Nobel laureate, RFdiffusion).
Seattle lead: Hetu Kamisetty (ex-IPD).
Investors: ARCH Venture Partners, Foresite Capital.
Peers: generate-biomedicines, lila-sciences, chai-discovery, isomorphic-labs, genbio-ai.

Sources

[1] Fierce Biotech, "New AI drug discovery powerhouse Xaira rises with $1B in funding" (2024-04; accessed 2026-10-14)
[2] Fierce Biotech, "'We've been taking our time': Xaira reveals antibody platform, first taste of pipeline" (accessed 2026-10-14)
[3] Business Wire, X-Cell announcement (2026-03-17); GEN Edge (2026-03-25) (accessed 2026-10-14)
[4] BioPharmaTrend, X-Atlas/Orion Perturb-seq atlas (2025-06; accessed 2026-10-14)
[5] Commercial Observer, Xaira lease expansion at 700 Gateway (2024-12); headcount from Revelio Labs estimate (accessed 2026-10-14)
[6] Sacra company profile (accessed 2026-10-14); aggregator funding figures (unverified)