Executive Summary

Interim data from REWRITE showed functional M-AAT protein produced in AATD patients, but single-dose KRRO-110 did not achieve the protective threshold; Korro is pivoting to a GalNAc-conjugated construct for AATD with a development candidate nomination targeted for H1 2026 .
Q3 financials: collaboration revenue $1.09M; net loss $18.06M; EPS -$1.92; cash, cash equivalents and marketable securities $102.5M as of 9/30/25, with runway extended into 2H 2027 following a 34% workforce reduction and restructuring charges estimated at ~$2.4M .
Novo Nordisk collaboration amended to a 12‑month pause to reassess the initial cardiometabolic target; Novo will reimburse certain wind-down costs during the hold period .
EPS beat against Zacks consensus (-$2.61), while revenue was below third‑party expectations; S&P Global (Capital IQ) Wall Street consensus was unavailable for Q3 2025 (we default to S&P Global when available) .

What Went Well and What Went Wrong

What Went Well

Functional M‑AAT protein observed in AATD patients at 0.8 mg/kg; durability up to four weeks in one patient, supporting clinical activity of RNA editing in humans. “We’re encouraged by the evidence of clinical activity, which we believe confirms our ability to edit RNA and produce therapeutic proteins in humans.” — Ram Aiyar, Ph.D., CEO .
Safety consistent with LNP class effects; no dose‑limiting toxicities or treatment‑emergent serious adverse events observed .
Platform expansion: nominated KRRO‑121 (GalNAc‑conjugated) for hyperammonemia (pan‑UCD and HE); first‑in‑human regulatory filing anticipated in H2 2026 .

What Went Wrong

Single‑dose KRRO‑110 did not reach protective total AAT threshold (11 µM); greatest peak total AAT ~10 µM and max increase ~3 µM, indicating underperformance versus projections based on preclinical data .
Pharmacokinetic differences between healthy volunteers and AATD patients (faster disassociation), suggesting variability of the current LNP formulation in patients and contributing to the pivot toward GalNAc delivery .
Strategic restructuring (34% workforce reduction) and 12‑month pause of the Novo collaboration introduce execution risk and near-term uncertainty, with ~$2.4M in one‑time charges expected (majority recognized in Q4 2025) .

Financial Results

Quarterly Performance (oldest → newest)

Metric	Q1 2025	Q2 2025	Q3 2025
Collaboration Revenue ($USD Millions)	$2.55	$1.46	$1.09
R&D Expense ($USD Millions)	$19.74	$21.03	$13.82
G&A Expense ($USD Millions)	$7.83	$7.63	$6.51
Net Loss ($USD Millions)	$23.39	$25.77	$18.06
EPS ($USD)	-$2.49	-$2.74	-$1.92
Cash, Cash Equivalents & Marketable Securities ($USD Millions)	$138.99	$119.63	$102.49

Year-over-Year (Q3 2025 vs Q3 2024)

Metric	Q3 2024	Q3 2025
Collaboration Revenue ($USD Millions)	$0.00	$1.09
R&D Expense ($USD Millions)	$16.00	$13.82
G&A Expense ($USD Millions)	$7.33	$6.51
Net Loss ($USD Millions)	$21.00	$18.06
EPS ($USD)	-$2.26	-$1.92

Actual vs Estimates (Q3 2025)

Metric	Q3 2025 Actual	Consensus (S&P Global)	Other Consensus (Zacks)
EPS ($USD)	-$1.92	Unavailable (S&P Global)	-$2.61
Revenue ($USD Millions)	$1.09	Unavailable (S&P Global)	Not disclosed

Note: S&P Global (Capital IQ) consensus data was unavailable for KRRO in Q3 2025; when available, we default to S&P Global.

Clinical KPIs and Safety (REWRITE)

KPI	Q1 2025	Q2 2025	Q3 2025
HV dosing progress	Trial expansion approvals; enrollment progressing; interim readout H2’25	>80% of planned HV dosed across SAD cohorts; no SAEs/DLTs	HV SAD complete (n=24; 0.04–1.2 mg/kg); patient cohorts at 0.6 mg/kg (n=3) and 0.8 mg/kg (n=4)
Safety	—	No SAEs/DLTs	No SAEs/DLTs; mild-to-moderate IRRs observed at highest HV dose and in patient cohorts; all resolved within 24 hours
Functional M‑AAT (µM increase)	—	—	Up to ~2 µM increase; observed in each LC/MS-evaluable patient at 0.8 mg/kg; durability up to 4 weeks (first patient)
Total AAT (µM)	—	—	Peak ~10 µM; max increase ~3 µM; protective threshold (11 µM) not reached
Specificity	—	—	No evidence of bystander editing (M‑AAT vs Z‑AAT LC/MS)

Guidance Changes

Metric	Period	Previous Guidance	Current Guidance	Change
Cash runway	Through 2027	“Into 2027” (Q1, Q2)	“Into 2H 2027” (post restructuring)	Raised (more specific and extended into 2H)
Workforce reduction	Immediate	~20% (Q1)	~34% (Q3) with ~$2.4M one-time charges (majority in Q4’25)	Raised (deeper cuts; charges added)
REWRITE timeline (KRRO‑110)	2025–2026	Interim readout H2’25; trial completion in 2026 (Q1/Q2)	Evaluating next steps for MAD; no plans for additional SAD patient cohorts	Lowered/Deferred (MAD reassessment)
AATD strategy	2026	—	Pivot to GalNAc-conjugated construct; DC nomination in H1 2026	New (strategic pivot)
KRRO‑121 (hyperammonemia)	H2 2026	DC announcement by end of 2025 (rare metabolic)	DC nominated; first-in-human regulatory filing anticipated H2 2026	Updated (from target to nominated; timeline set)
Novo Nordisk collaboration	2025–2026	Progressing preclinical for up to two programs	12‑month pause to reassess initial target; Novo reimburses wind‑down costs	Lowered (paused)

Earnings Call Themes & Trends

Topic	Previous Mentions (Q-2 and Q-1)	Current Period (Q3 2025)	Trend
AATD clinical progress	HV dosing advancing; orphan drug designations (FDA, EMA); interim readout H2’25	Functional M‑AAT observed; protective threshold not met; formulation variability in patients; evaluating MAD next steps	Mixed (proof-of-mechanism with underwhelming magnitude)
Delivery strategy (LNP vs GalNAc)	LNP in HV dosing; GalNAc program planned for rare metabolic disorder	Pivot to GalNAc for AATD; broader liver-targeted GalNAc programs advancing	Shift to GalNAc
Platform expansion (OPERA)	“3‑2‑1” strategy; second DC expected by end of 2025	KRRO‑121 nominated; first-in-human filing H2’26	Executing (pipeline broadening)
Regulatory designations	FDA ODD (Mar’25); EMA ODD (Jul’25) for KRRO‑110	Fast Track designation and orphan status reiterated	Supportive
Partnership (Novo Nordisk)	Collaboration progressing on cardiometabolic	12‑month pause to reassess target	Negative near-term
Cost discipline / runway	Workforce -20%; runway into 2027	Workforce -34%; runway into 2H 2027	More conservative cost base

Note: No Q3 2025 earnings call transcript was available in our document corpus; themes reflect press releases and the 8‑K .

Management Commentary

“KRRO‑110 generated functional M‑AAT protein in AATD patients… we believe [this] confirms our ability to edit RNA and produce therapeutic proteins in humans.” — Ram Aiyar, Ph.D., CEO .
“Initial analysis indicates differences in the pharmacokinetics of the delivery components… observed between healthy volunteers and AATD patients.” — Ram Aiyar, Ph.D. .
“We are implementing a strategic restructuring that reduces our workforce by approximately a third while extending our cash runway into the second half of 2027.” — Ram Aiyar, Ph.D. .
“We have nominated our next development candidate, KRRO‑121… a GalNAc‑conjugated construct… for patients with hyperammonemia.” — Management statement .

Q&A Highlights

No Q3 2025 earnings call transcript was available; therefore, Q&A highlights and any guidance clarifications from a call are unavailable based on our sources .
For clarifications, Korro indicated it is evaluating next steps for KRRO‑110’s MAD portion and is pivoting to GalNAc for AATD .

Estimates Context

EPS: Actual -$1.92 beat Zacks consensus of -$2.61 (positive surprise); S&P Global consensus was unavailable for KRRO in Q3 2025 and is our default source when available .
Revenue: $1.09M in collaboration revenue; S&P Global consensus unavailable; third‑party commentary indicated a revenue miss vs expectations but did not disclose a numeric consensus .
Forward revisions: Expect model updates reflecting AATD pivot to GalNAc (longer near‑term clinical path) and reduced opex trajectory from restructuring; KRRO‑121 timelines (H2’26 filing) may adjust program probability‑of‑success and spend curves .

Key Takeaways for Investors

Proof‑of‑mechanism achieved: human functional M‑AAT detected validates RNA editing in clinic, but magnitude below protective threshold implies need for delivery optimization; pivot to GalNAc is a rational course correction .
Cost actions deepen (34% reduction), extending runway into 2H 2027; near‑term dilution risk reduced, but execution capacity must be watched post headcount cuts .
Novo pause removes a near-term catalyst in cardiometabolic; reassessment may ultimately sharpen focus, but it is a temporary overhang .
KRRO‑121 nomination adds a second clinical path with a clear first‑in‑human filing target in H2 2026, diversifying beyond protein repair into pathway activation for hyperammonemia .
Q3 print shows tighter opex discipline (R&D and G&A down YoY) and an EPS beat vs third‑party consensus; revenue remains collaboration‑driven and lumpy .
Trading lens: watch for detailed GalNAc construct data packages, MAD decisioning on KRRO‑110, and formal KRRO‑121 regulatory interactions; these are likely narrative movers ahead of 2026 .
Risk management: clinical variability in AATD patients, partnership pausing, and organizational changes elevate execution risk; cash runway provides optionality to hit next data milestones without immediate financing .

Sources: Q3 2025 8‑K and press release including exhibit, and prior quarter earnings releases . External consensus reference: Yahoo/Zacks article . Press release archive and IR site .

Korro Bio, Inc. (KRRO)·Q3 2025 Earnings Summary