Cautionary Note Regarding Forward-Looking Statements This presentation contains "forward-looking statements" within the meaning of the federal securities laws, which statements are subject to substantial risks and uncert

Nasdaq: ETNB Powerful Science

Meaningful Medicines Changing Lives June 2021 Exhibit 99.1

Cautionary Note Regarding

Forward-Looking Statements This presentation contains "forward-looking statements" within the meaning of the federal securities laws, which statements are subject to substantial risks and uncertainties and are based on estimates and

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performance, financing needs, plans or intentions relating to product candidates, estimates of market size, business trends, the anticipated timing, costs, design, endpoints and conduct of our planned and ongoing clinical trials for BIO89-100, our

only product candidate, the association of preclinical data with potential clinical benefit, the timing of anticipated milestones, the effect of the COVID-19 pandemic on our clinical trials and business operations, the timing and likelihood of

regulatory filings and approvals for BIO89-100, our ability to commercialize BIO89-100, if approved, the pricing and reimbursement of BIO89-100, if approved, the potential to develop future product candidates, our ability to scale up manufacturing,

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89bio - Investment Highlights Highly

differentiated FGF21 using GlycoPEGylation technology to optimize efficacy and dosing Validated with compelling profile: strong efficacy, favorable safety/tolerability, and potential best-in-class dosing BIO89-100 has potential to be a leading DRUG

FOR LIVER AND CARDIO-METABOLIC DISORDERS STRONG CAPITAL POSITION - $189.6M IN CASH, cash equivalents, and short-term investments (MAR 31, 2021) PURSUING Two Promising Large Indications WITH COMPETITIVELY DIFFERENTIATED PROFILE NASH: Potential

backbone treatment addressing multiple facets of NASH SHTG: Potential to treat TGs and metabolic dysregulation with quicker path to market PROGRAM STATUS/MILESTONES NASH: Phase 2b ENLIVEN trial ongoing; Topline data from paired-biopsy, open-label

histology cohort by YE21 SHTG: Topline data from Phase 2 ENTRIGUE trial in 1H22 ESTABLISHED MANUFACTURING EXPERTISE AND IP PROTECTION INTO 2038 AND BEYOND

Indication Preclinical Phase 1 Phase 2

Phase 3 NASH SHTG Phase 1b/2a histology cohort Advancing BIO89-100 in Clinical Development Phase 2b trial Phase 2 trial Phase 2 fibrate cohort

NASH is a Serious Liver Condition With

Significant Co-Morbidities No treatments currently available 16.5 million cases projected to grow to 27 million cases by 2030 Expected to become the leading cause of liver transplant Co-morbidity Prevalence in NASH population Hypertriglyceridemia

83% Obesity 82% Hyperlipidemia / Dyslipidemia 72% Metabolic syndrome 71% Type 2 diabetes 44% Metabolic Dysregulation Excess Liver Fat Accumulation Progressive Disease

FGF21 Has Potential To Be Mainstay of

Therapy In NASH Endogenous metabolic hormone that regulates energy expenditure and glucose and lipid metabolism Reduces liver fat by action within liver and from periphery Impacts liver fibrosis via metabolic pathway and upregulation of adiponectin

Native FGF21 has a short half-life of < 2 hours Lipid clearance Insulin sensitivity FGF21 Glucose uptake Lipolysis Energy expenditure Adipogenesis M2 M polarization M2 M

proliferation Reproduction Circadian activity Adipose Muscle Gluconeogenesis Cholesterol excretion Cholesterol biogenesis Lipid clearance Insulin sensitivity Ceramide accumulation Liver

Vascular protection Blood vessel HPA axis FGF21 adiponectin FGF21

BIO89-100 Is An FGF21 Optimally

Engineered To Balance Potential for Efficacy and Long Dosing Interval glycoPEG(20kD) C-terminus X Strong and flexible linker (glycoPEGylation technology) Mutations in positions 173 and 176 (glycoPEG attached at position 173) X N-terminus Position

182 FGF21 Proprietary glycoPEGylation technology with site-specific mutations Increases half-life of native FGF21 (< 2 hours) to 55-100 hours based on single ascending dose study Low nanomolar potency against FGF receptors 1c, 2c, 3c, similar to

native FGF21 No activity against FGF receptor 4 which is the primary target of FGF19, and which can lead to increased LDL levels C-terminus N-terminus FGFR FGFR C-terminus -Klotho -Klotho Signal transduction Functional

Phase 1b/2a NASH Trial Design MRI-PDFF

SCREENING RANDOMIZATION Wk 12 NASH* or phenotypic NASH (PNASH)# PDFF 10% *Patients with biopsy-proven F1-3 #Central obesity plus T2DM or evidence of liver injury KEY INCLUSION CRITERIA Safety, PK Relative changes in liver fat Serum lipids,

liver and metabolic markers KEY TRIAL ENDPOINTS Wk 7 SAFETY FOLLOW-UP Placebo (n=19) combined across cohorts for analysis Randomized, pharmacodynamic (PD) and safety analysis set n=81; Study completers n=71 MRI analysis set n=75 (patients with

post-baseline MRI) 36mg Q2W (n=9) Placebo Q2W (n=3) 27mg QW (n=10) Placebo QW (n=3) 18mg QW (n=11) Placebo QW (n=4) 18mg Q2W (n=14) Placebo Q2W (n=4) 9mg QW (n=12) Placebo QW (n=3) 3mg QW (n=6) Placebo QW (n=2)

Majority of Patients on BIO89-100

Achieved 50% Reduction in Liver Fat MRI Analysis Set; MMRM LS Mean; * p<0.05; ** p<0.01; *** p<0.001 versus placebo; placebo relative increase of 10% from baseline ^ 60% relative reduction in liver fat vs. placebo when final 2

patients from this dose group were excluded in a post-hoc analysis. These 2 patients came from 2 separate newly activated sites which came online just before the study closed enrollment in the midst of the COVID pandemic Relative Reduction in

Liver Fat versus Placebo at Week 13 *** *** ^ *** *** *** ***

Up to 43% of patients normalized

their liver fat (<5%) 30% relative reduction in liver fat has been correlated with NASH resolution and fibrosis improvement 71% of patients on 27 mg QW dose had 70% relative reduction in liver fat Significant Numbers of Patients

Achieved Clinically Meaningful Responder Rates on BIO89-100 30% Relative Reduction in Liver Fat 50% Relative Reduction in Liver Fat Placebo 0% 0% 3mg QW 60%** 20% 9mg QW 82%*** 54%*** 18mg QW^ 60%** 50%** 27mg QW 86%*** 71%*** 18mg Q2W

69%** 39%** 36mg Q2W 88%*** 50%** MRI Analysis Set; MMRM LS Mean; * p<0.05; ** p<0.01; *** p<0.001 versus placebo ^ 75% and 63% patients achieved a 30% and a 50% reduction in liver fat vs. baseline when final 2 patients from

this dose group were excluded in a post-hoc analysis. These 2 patients came from 2 separate newly activated sites which came online just before the study closed enrollment in the midst of the COVID pandemic

Baseline characteristics were

similar between NASH and PNASH patients Reductions in absolute percentage of liver fat from baseline, % responders on MRI-PDFF and BIO89-100's effect on reducing ALT and TGs were also similar across NASH and PNASH patients BIO89-100

Significantly Reduced Liver Fat Across All Dose Groups MRI Analysis Set; MMRM LS Mean; * p<0.05; ** p<0.01; *** p<0.001 versus placebo ^ 10% absolute reduction in liver fat from baseline when final 2 patients from this dose group were

excluded in a post-hoc analysis. These 2 patients came from 2 separate newly activated sites which came online just before the study closed enrollment in the midst of the COVID pandemic ** *** *** *** *** *** Absolute Change in Liver Fat (%)

from Baseline at Week 13 Q2W QW

BIO89-100 Significantly Reduced ALT

with Greater Reduction Observed in Patients with Elevated Baseline ALT *** * * *** Percent Change from Baseline at Week 13 -30 U/L -22 U/L Q2W QW Absolute change: n=5 n=17 Placebo Pooled BIO89-100 * Absolute Change in ALT at Week 13 (Baseline ALT

> 45 U/L) PD Analysis Set in baseline ALT > 45 U/L (placebo n=6, pooled BIO89-100 n=22); Pre-planned sensitivity analysis; MMRM LS Mean; * p<0.05; ** p<0.01; *** p<0.001 versus placebo Change in ALT of 17 U/L has been

correlated with improvement in fibrosis

Decrease from baseline in BIO89-100

treated subgroup with baseline TG 200 mg/dL TG: 33%-49% Non-HDL: 8%-29% BIO89-100 Significantly Reduced Triglycerides with Greater Benefit Observed in Patients with High Triglycerides PD Analysis Set; MMRM LS Mean; * p<0.05; ** p<0.01;

*** p<0.001 versus placebo; # TG <150 mg/dL TG at baseline (Total population): Pooled BIO89-100 (174.4 mg/dL) and Placebo (174.0 mg/dL) TG at baseline (Subgroup with Baseline 200 mg/dL): Pooled BIO89-100 (288.1 mg/dL) and Placebo

(228.0 mg/dL) * * * Percentage Change from Baseline at Week 13 (All Patients) Q2W QW TG Normalization# Rate at week 13 (Subgroup with Baseline TG 200 mg/dL) 53%

BIO89-100 (27 mg QW) Improved

Metabolic Markers *** * HbA1c (%) placebo adjusted change from baseline = -0.3 PD Analysis Set; MMRM LS Mean; * p<0.05; ** p<0.01; *** p<0.001 versus placebo. Placebo HOMA-IR: -0.1%; Glucose: +7.9%; HbA1c +0.61%; Weight: +1.4% Adiponectin:

BIO89-100 Demonstrated a Favorable

Safety Profile Treatment Emergent Adverse Event (TEAE) Placebo (n=18) 3mg QW (n=7) 9mg QW (n=12) 18mg QW (n=11) 27mg QW (n=10) 18mg Q2W (n=14) 36mg Q2W (n=9) TEAE Leading to Death 0 0 0 0 0 0 0 TEAE Leading to Discontinuation 0 0 0 0 1a 1b 0 Serious

Adverse Event COVID 19 [Not Drug Related] 0 0 0 0 0 1 1 Safety Analysis Set; one placebo patient received one dose of BIO89-100 3mg and is summarized in 3mg QW group a skin rash; b hyperglycemia [Not Drug Related]

BIO89-100 Was Well Tolerated Across

Doses Low Incidence of Treatment-Related Emergent AEs in 10% of Pooled BIO89-100 Group Preferred Term n (%) Placebo (n=18) Pooled BIO89-100 (n=63) 3mg QW (n=7) 9mg QW (n=12) 18mg QW (n=11) 27mg QW (n=10) 18mg Q2W (n=14) 36mg Q2W (n=9)

Increased Appetite 0.0% 15.9% 4 2 0 2 2 0 Safety Analysis Set; one placebo subject received one dose of BIO89-100 3mg and is summarized in 3mg QW group GI related AEs were similar to placebo Diarrhea: 9.5% vs. 11.1% (Pooled BIO89-100 vs. Placebo)

Nausea: 4.8% vs. 11.1% (Pooled BIO89-100 vs. Placebo) Vomiting: 0.0% vs. 0.0% (Pooled BIO89-100 vs. Placebo) No hypersensitivity AE reported; few mild injection site reaction events reported No tremor reported; no adverse effects on blood pressure

Phase 1b/2a NASH Open-label

Histology Cohort Trial Design F2-F3* NASH; NAS 4 MRI-PDFF 8% KEY INCLUSION CRITERIA Liver Biopsy SCREENING Wk 20 SAFETY FOLLOW-UP 27mg QW BIO89-100 B B Fibrosis Improvement NASH Resolution Liver fat (MRI-PDFF) Non-invasive tests KEY

SECONDARY ENDPOINTS PRIMARY ENDPOINT B 2 improvement in NAS Safety/tolerability * Limited number of high-risk F1 20 weeks

Phase 2b (ENLIVEN) NASH Trial Design

F2-F3 NASH; NAS 4 MRI-PDFF 8% KEY INCLUSION CRITERIA Other histological endpoints NITs - Pro-C3, ELF, FIB-4 cT1 Lipid and metabolic assessments Liver fat (MRI-PDFF) Safety OTHER ENDPOINTS Fibrosis Improvement NASH Resolution

PRIMARY ENDPOINTS SCREENING RANDOMIZATION B B PLACEBO (QW or Q2W) BIO89-100 15mg QW BIO89-100 30mg QW BIO89-100 44mg Q2W PLACEBO Q2W BIO89-100 15mg QW BIO89-100 30mg QW BIO89-100 44mg Q2W MAIN STUDY (24 weeks) EXTENSION PHASE (24 weeks) MRI-PDFF

Liver Biopsy B PLACEBO* (QW or Q2W) Wk 24 Wk 48 Wk 12 End of Phase 2 meeting * Some placebo patients will be re-randomized in the extension phase to receive BIO89-100

Comparative Profile of FGF21 Analogs

BIO89-100 Efruxifermin Pegbelfermin Structure GlycoPEGylated FGF21 Fc-fused FGF21 PEGylated FGF21 (with non-native amino acid substitution) Efficacy Significant effect on liver parameters Robust impact on broad metabolic parameters EFX demonstrated

positive data in F4 patients Lower effects across all liver and metabolic parameters Tolerability Well-tolerated at all doses Placebo-like GI profile No tremors High frequency and withdrawals from GI events in all 3 clinical studies Tremors observed

in MAD and Phase 2a studies Similar to BIO89-100 Dosing Frequency Weekly and Every Two-Weeks Weekly Daily or Weekly Phase 2b Drug Product Liquid Frozen Liquid Development Timelines Phase 2b (F2/F3) initiated in 2Q21 Phase 2b (F2/F3) initiated in

1Q21 Phase 2b (F3 and F4) complete - results pending Note: All data regarding third-party studies on this slide are based third-party studies, which are in different stages of development, and not our own. Conclusions on this slide are not based on

head-to-head results. Response rates are not guaranteed to maintain the same levels in future clinical studies.

Diagnosis and treatment rates

expected to increase in the future SHTG Market Is Large with Significant Unmet Need * 50% is based on registrational trials of Vascepa and Epanova (at 4mg/day dose) approved in SHTG LARGE PATIENT POPULATION WITH HIGH UNMET NEED AND MULTIPLE

CO-MORBIDITIES Estimated up to 4 million patients Characterized by severely elevated TG levels ( 500 mg/dL); TGs are a type of non-cholesterol fat Up to 70% of patients have other dyslipidemias or Type 2 Diabetes Up to 50%* of treated

patients are refractory to current standard of care 56% of patients have hepatic fat Primary research with physicians confirms unmet need and co-morbidities as above

FISH OILS FIBRATES Vascepa (EPA)

Lovaza (EPA+DHA) Tricor Reduce Hepatic Fat - - - Improve LDL-C - Worsens LDL Worsens LDL ALT - Warnings, Monitoring Required Glycemic Control - - - Tolerability/ Safety May prolong bleeding time Myopathy, Creatinine increases, DDI Current Therapies

Reached Blockbuster Status Despite Falling Short on Safety and Effect on Co-Morbidities TG LDL-C Unchanged or Inconclusive - * Conclusions on this slide are not based on head-to-head results Changes from baseline Vascepa Lovaza Tricor ~$1B (Peak)

>$1B (Peak) $614.1M in 2020 Unlike other therapies, BIO89-100 addresses the broad metabolic issues in these patients US approval endpoint: % change in TGs from baseline; no clinical outcomes study required Ph 3 trials precedent*: Single 12-wk

trials with ~200-300 pts

Decrease from baseline in BIO89-100

treated subgroup with baseline TG 200 mg/dL TG: 33%-49% Non-HDL: 8%-29% BIO89-100 Significantly Reduced Triglycerides with Greater Benefit Observed in Patients with High Triglycerides PD Analysis Set; MMRM LS Mean; * p<0.05; ** p<0.01;

*** p<0.001 versus placebo; # TG <150 mg/dL * * * Percentage Change from Baseline at Week 13 (All Patients) Q2W QW TG Normalization# Rate at week 13 (Subgroup with Baseline TG 200 mg/dL) 53% % change from baseline at week 13 (27mg QW