Nasdaq: CBIO HARNESSING THE CATALYTIC POWER OF PROTEASES Complement R&D Day 19 July 2021 CatalystBiosciences.com Forward-looking statements Certain information contained in this presentation and statements made orally du

Complement R&D Day 19 July 2021 CatalystBiosciences.comExhibit 99.1 Nasdaq: CBIO HARNESSING THE CATALYTIC POWER OF PROTEASES Complement R&D Day 19 July 2021 CatalystBiosciences.com

Forward-looking statements Certain information contained in this

presentation and statements made orally during this presentation include forward-looking statements that involve substantial risks and uncertainties. All statements included in this presentation, other than statements of historical facts, are

forward looking statements. Forward-looking statements include, without limitation, statements about the product candidates of Catalyst Biosciences, Inc. (the "Company") and the benefits of its protease engineering platform; the

potential markets for and advantages of the Company's complement product candidates, including CB 2782-PEG, CB 4332 and complement degraders; plans for the Company's collaboration with Biogen; and plans to enroll the CB 4332 observational trial in

mid-2021 and to conduct human clinical trials and report pK and biomarker data for CB 4332 in 2022. Actual results or events could differ materially from the plans, intentions, expectations and projections disclosed in the forward-looking

statements. Various important factors could cause actual results or events to differ materially, including, but not limited to, the risk that trials and studies may be delayed as a result of COVID-19 and other factors, that trials may not have

satisfactory outcomes, the risk that costs required to develop or manufacture the Company's products will be higher than anticipated, including as a result of delays in development and manufacturing resulting from COVID-19 and other factors,

the risk that Biogen will terminate its agreement with the Company, competition and other risks described in the "Risk Factors" section of the Company's Annual Report on Form 10-K filed with the Securities and Exchange Commission (

SEC ) on March 4, 2021, on Form 10-Q filed with the SEC on May 6, 2021, and in other filings with the SEC. The forward-looking statements in this presentation represent the Company's view as of the date of this presentation and the Company does not

assume any obligation to update any forward-looking statements, except as required by law. 2Forward-looking statements Certain information contained in this presentation and statements made orally during this presentation include forward-looking

statements that involve substantial risks and uncertainties. All statements included in this presentation, other than statements of historical facts, are forward looking statements. Forward-looking statements include, without limitation, statements

about the product candidates of Catalyst Biosciences, Inc. (the "Company") and the benefits of its protease engineering platform; the potential markets for and advantages of the Company's complement product candidates, including CB

2782-PEG, CB 4332 and complement degraders; plans for the Company's collaboration with Biogen; and plans to enroll the CB 4332 observational trial in mid-2021 and to conduct human clinical trials and report pK and biomarker data for CB 4332 in 2022.

Actual results or events could differ materially from the plans, intentions, expectations and projections disclosed in the forward-looking statements. Various important factors could cause actual results or events to differ materially, including,

but not limited to, the risk that trials and studies may be delayed as a result of COVID-19 and other factors, that trials may not have satisfactory outcomes, the risk that costs required to develop or manufacture the Company's products will

be higher than anticipated, including as a result of delays in development and manufacturing resulting from COVID-19 and other factors, the risk that Biogen will terminate its agreement with the Company, competition and other risks described in the

"Risk Factors" section of the Company's Annual Report on Form 10-K filed with the Securities and Exchange Commission ( SEC ) on March 4, 2021, on Form 10-Q filed with the SEC on May 6, 2021, and in other filings with the SEC. The

forward-looking statements in this presentation represent the Company's view as of the date of this presentation and the Company does not assume any obligation to update any forward-looking statements, except as required by law. 2

Welcome Catalyst Biosciences: The Protease Medicines Company Nassim

Usman, Ph.D. | President & CEO

Complement R&D Day - July 2021 Agenda Time Topic (Speaker)

12:00 - 12:05 pm Catalyst Biosciences: The Protease Medicines Company Nassim Usman, Ph.D. | Catalyst President & CEO 12:05 - 12:25 pm The Need for Complement Factor I Replacement Filomeen Haerynck, M.D., Ph.D. | KOL, Ghent University 12:25 -

12:45 pm Growing Complement Pathway Protease Platform Grant Blouse, Ph.D. | Catalyst CSO 12:45 - 12:50 pm Milestones Clinton Musil | Catalyst CFO 12:50 - 1:10 pm Q&A Session 4Complement R&D Day - July 2021 Agenda Time Topic (Speaker)

12:00 - 12:05 pm Catalyst Biosciences: The Protease Medicines Company Nassim Usman, Ph.D. | Catalyst President & CEO 12:05 - 12:25 pm The Need for Complement Factor I Replacement Filomeen Haerynck, M.D., Ph.D. | KOL, Ghent University 12:25 -

12:45 pm Growing Complement Pathway Protease Platform Grant Blouse, Ph.D. | Catalyst CSO 12:45 - 12:50 pm Milestones Clinton Musil | Catalyst CFO 12:50 - 1:10 pm Q&A Session 4

The Protease Medicines Company Harnessing the catalytic power of

proteases Novel differentiated medicines Robust complement portfolio Clinical-stage assets Unique expertise in protease engineering 5The Protease Medicines Company Harnessing the catalytic power of proteases Novel differentiated medicines Robust

complement portfolio Clinical-stage assets Unique expertise in protease engineering 5

Catalyst protease platform Unique expertise enables design of optimized

& differentiated protease candidates Discovery Platform Our Proteases + Functionally enhance Protease Protease natural proteases in Scaffold Candidate the complement & coagulation cascades + Engineer novel protein degraders in the complement

cascade + Modulate or target biological activation or inactivation Structure Guided Design Engineered Regulation Molecular Evolution Pharmacokinetic Improvement 6Catalyst protease platform Unique expertise enables design of optimized &

differentiated protease candidates Discovery Platform Our Proteases + Functionally enhance Protease Protease natural proteases in Scaffold Candidate the complement & coagulation cascades + Engineer novel protein degraders in the complement

cascade + Modulate or target biological activation or inactivation Structure Guided Design Engineered Regulation Molecular Evolution Pharmacokinetic Improvement 6

CB 2782-PEG (nM) Catalyst protease platform Validated across three

programs Marzeptacog alfa Dalcinonacog alfa CB 2782-PEG (activated) 90% reduction Achieved sustained Best-in-class profile for dry AMD in annualized bleed rate & high target levels of FIX Extended pharmacodynamics 6 10000 Normal clotting levels

5 1000 4 100 50% 3 Mild Hemophilia 10 2 5% 1 1 Moderate Hemophilia 1% 0 0.1 Severe Hemophilia 0 10 20 30 40 50 Before treatment On treatment Days Engineered Engineered Novel rFVIIa protease rFIX protease C3 degrader 7 C3 Concentration (nM)CB

2782-PEG (nM) Catalyst protease platform Validated across three programs Marzeptacog alfa Dalcinonacog alfa CB 2782-PEG (activated) 90% reduction Achieved sustained Best-in-class profile for dry AMD in annualized bleed rate & high target levels

of FIX Extended pharmacodynamics 6 10000 Normal clotting levels 5 1000 4 100 50% 3 Mild Hemophilia 10 2 5% 1 1 Moderate Hemophilia 1% 0 0.1 Severe Hemophilia 0 10 20 30 40 50 Before treatment On treatment Days Engineered Engineered Novel rFVIIa

protease rFIX protease C3 degrader 7 C3 Concentration (nM)

Growing Complement Pathway Protease Platform Grant E. Blouse, Ph.D. |

Chief Scientific OfficerGrowing Complement Pathway Protease Platform Grant E. Blouse, Ph.D. | Chief Scientific Officer

Proteases are ideal for high abundancy targets & cascades A better

way to regulate biological processes compared with antibodies & small molecules Therapeutic target neutralization Protease Efficient regulation at low concentrations of therapeutic protease Antibodies Requires high concentrations in excess of

the target Small molecules / peptides Requires high concentrations & frequent dosing 9Proteases are ideal for high abundancy targets & cascades A better way to regulate biological processes compared with antibodies & small molecules

Therapeutic target neutralization Protease Efficient regulation at low concentrations of therapeutic protease Antibodies Requires high concentrations in excess of the target Small molecules / peptides Requires high concentrations & frequent

Multiple, high-value complement programs Future Degraders NextGen

Degraders Our Lead Candidate Novel Engineered Degrader Partnered with Biogen C3a C4b CB 2782-PEG CB 4332 C3b C5a Established Catalyst Biosciences in complement Leads expansion into systemic complement in CFI Specific & potent degraders

dysregulation target classical & alternative Broadens Catalyst complement disorders with Biosciences footprint in large-market potential the complement space 10Multiple, high-value complement programs Future Degraders NextGen Degraders Our Lead

Candidate Novel Engineered Degrader Partnered with Biogen C3a C4b CB 2782-PEG CB 4332 C3b C5a Established Catalyst Biosciences in complement Leads expansion into systemic complement in CFI Specific & potent degraders dysregulation target

classical & alternative Broadens Catalyst complement disorders with Biosciences footprint in large-market potential the complement space 10

Unique targeted approach to complement regulation Cascade initiation

Cascade regulation Terminal complement C4b Degraders NextGen Degraders CB 2782-PEG C3b Degraders Other programs CB 4332 C2 C1r Classical C4b C3a pathway C1s C4 Immune response inflammation Lectin C3b C3 C5a C5 MASP pathway C3 Alternative C3b FB C5b

FD (H O) pathway 2 Membrane attack complex (MAC) 11Unique targeted approach to complement regulation Cascade initiation Cascade regulation Terminal complement C4b Degraders NextGen Degraders CB 2782-PEG C3b Degraders Other programs CB 4332 C2 C1r

Classical C4b C3a pathway C1s C4 Immune response inflammation Lectin C3b C3 C5a C5 MASP pathway C3 Alternative C3b FB C5b FD (H O) pathway 2 Membrane attack complex (MAC) 11

CB 2782-PEG Novel engineered C3 degrader in complement 12CB 2782-PEG

Novel engineered C3 degrader in complement 12

CB 2782-PEG: Long acting anti-C3 protease for dry AMD Geographic

atrophy is a Best-in-class C3 Biogen collaboration high unmet need degrader for dry AMD + Advanced stage of dry age- + Generated from Catalyst's + $15M upfront, up to $340M in related macular degeneration proprietary protease milestones &

tiered royalties (dAMD) engineering platform up to low double digits + dAMD affects ~1M people in the + Potent, selective & long + Catalyst: fully funded pre- US & >5M WW, no currently acting, degrades C3 into clinical & manufacturing

approved therapy inactive fragments activities + Global market ~ >$5B + NHP PK & PD data* predict + Biogen: IND-enabling best-in-class human activities, WW clinical intravitreal dosing 3 or 4 development & + C3 is a clinically validated

target times a year commercialization (randomized P2) for dAMD *Furfine et al. ARVO 2019 13

CB 2782-PEG (nM) CB 2782-PEG (nM) CB 2782-PEG: Best-in-class C3

degrader for dry AMD Protease advantage demonstrated in vivo CB 2782-PEG degrades C3 levels in the eye for at Catalytic advantage of proteases least 28 days in a non-human primate model + One therapeutic molecule 6 10000 neutralizes 1000s 5 1000 +

Fast & potent response 4 + Extended pharmacodynamic effect 100 3 + Can activate or degrade 10 therapeutic targets 2 + Engineered novel protein 1 1 degraders "sweep away" difficult to drug targets 0 0.1 0 10 20 30 40 50 Days Days 14

C3 Concentration (nM) C3 Concentration (nM)CB 2782-PEG (nM) CB 2782-PEG (nM) CB 2782-PEG: Best-in-class C3 degrader for dry AMD Protease advantage demonstrated in vivo CB 2782-PEG degrades C3 levels in the eye for at Catalytic advantage of proteases

least 28 days in a non-human primate model + One therapeutic molecule 6 10000 neutralizes 1000s 5 1000 + Fast & potent response 4 + Extended pharmacodynamic effect 100 3 + Can activate or degrade 10 therapeutic targets 2 + Engineered novel

protein 1 1 degraders "sweep away" difficult to drug targets 0 0.1 0 10 20 30 40 50 Days Days 14 C3 Concentration (nM) C3 Concentration (nM)

CB 2782-PEG: Comparison to APL-2 & NGM621 Potential for a less

frequent dosing regimen in dry AMD APL-2 (Apellis) NGM621 (NGM Bio) CB 2782-PEG Category PEGylated cyclic peptide Antibody anti-C3 Protease Targets C3 Yes Yes Yes Dose Frequency Every 1-2 months Every 1-2 months Every ~3 months* Half-life in Cyno VH

3.2 days n/a 4.1 days Dose level 15 mg (high) 15 mg (none) up to 1 mg (low) (risk of PEG overload) 15 *Frequency estimated based on ocular PK-PD data in non-human primatesCB 2782-PEG: Comparison to APL-2 & NGM621 Potential for a less frequent

dosing regimen in dry AMD APL-2 (Apellis) NGM621 (NGM Bio) CB 2782-PEG Category PEGylated cyclic peptide Antibody anti-C3 Protease Targets C3 Yes Yes Yes Dose Frequency Every 1-2 months Every 1-2 months Every ~3 months* Half-life in Cyno VH 3.2 days

n/a 4.1 days Dose level 15 mg (high) 15 mg (none) up to 1 mg (low) (risk of PEG overload) 15 *Frequency estimated based on ocular PK-PD data in non-human primates

CB 4332: Enhanced Complement Factor I Next clinical candidate

Complement Factor I CFI is a key down-regulator of the complement

cascade Applying the brakes to complement Classical Lectin Alternate pathway pathway pathway CFI is a key regulator of complement MBL C3(H O) C1q 2 activation targeting both C3b & C4b C1r Classical & lectin pathway inhibitor MASPs

CFD CFB C1s Alternative pathway inhibitor C4 C2 CFI deficiency triggers uncontrolled pathway activation C3b Bb C4b 2b Secondary complement deficiency C3 Significant C3 depletion CFI Susceptibility to infections &

increased autoimmune complex diseases 17Complement Factor I CFI is a key down-regulator of the complement cascade Applying the brakes to complement Classical Lectin Alternate pathway pathway pathway CFI is a key regulator of complement MBL C3(H O)

C1q 2 activation targeting both C3b & C4b C1r Classical & lectin pathway inhibitor MASPs CFD CFB C1s Alternative pathway inhibitor C4 C2 CFI deficiency triggers uncontrolled pathway activation C3b Bb C4b 2b Secondary

complement deficiency C3 Significant C3 depletion CFI Susceptibility to infections & increased autoimmune complex diseases 17

CB 4332: SQ Enhanced Complement Factor I Development candidate to

restore regulation Rationale & unmet need + Rebalance the complement system in patients with dysregulated CFI + No specific therapies exist to correct CFI dysregulation + Targets population with no + Engineered for an extended half-life

treatment or who respond + Once weekly SQ therapy - no PEG 1,2 poorly to current treatments + In vitro & Ex vivo activity comparable to native CFI + Classical & alternative pathway regulation + High yield production process 1 2

References: Bienaime et al. Kidney Int. 2010; Ferreira et al. Nefrologia. 2016; Note: CFH = Complement factor H; Structural model based on PDB 2XRC. 18CB 4332: SQ Enhanced Complement Factor I Development candidate to restore regulation Rationale

& unmet need + Rebalance the complement system in patients with dysregulated CFI + No specific therapies exist to correct CFI dysregulation + Targets population with no + Engineered for an extended half-life treatment or who respond + Once

weekly SQ therapy - no PEG 1,2 poorly to current treatments + In vitro & Ex vivo activity comparable to native CFI + Classical & alternative pathway regulation + High yield production process 1 2 References: Bienaime et al. Kidney Int.

2010; Ferreira et al. Nefrologia. 2016; Note: CFH = Complement factor H; Structural model based on PDB 2XRC. 18

CB 4332: To address CFI deficiency at the root cause Designed to

provide unique advantages CB 4332 Unmet needs in CFI deficiency Designed to address Blocks complement-initiated cell destruction in the circulation Directly addresses root cause of disease Addresses extravascular hemolysis Preserves normal immune

functions, e.g. to fight off infections Convenient weekly SQ administration 19CB 4332: To address CFI deficiency at the root cause Designed to provide unique advantages CB 4332 Unmet needs in CFI deficiency Designed to address Blocks

complement-initiated cell destruction in the circulation Directly addresses root cause of disease Addresses extravascular hemolysis Preserves normal immune functions, e.g. to fight off infections Convenient weekly SQ administration 19

Screening & natural history of disease studies ConFIrm &

ConFIdence: preparing for Phase 1/2 Identifies Target Population / Feeds ConFIdence Study / Discovers Undiagnosed Disease The ConFIrm Study CB CB 4 43 33 32 2 CB 4332 Ph Pha ase se 1 1//2 2 Phase 1/2 Tr Triia alls s Trials Sc Scr re ee en niin ng g

The ConFIdence Study Prospective Clinical & Biomarkers Assessment of CFI-Deficiency Disease While on SoC Identification of CFI-deficient patients & key investigators for CB 4332 trials Discover undiagnosed disease, create program awareness

& inform on biomarkers 20Screening & natural history of disease studies ConFIrm & ConFIdence: preparing for Phase 1/2 Identifies Target Population / Feeds ConFIdence Study / Discovers Undiagnosed Disease The ConFIrm Study CB CB 4 43 33

32 2 CB 4332 Ph Pha ase se 1 1//2 2 Phase 1/2 Tr Triia alls s Trials Sc Scr re ee en niin ng g The ConFIdence Study Prospective Clinical & Biomarkers Assessment of CFI-Deficiency Disease While on SoC Identification of CFI-deficient patients

& key investigators for CB 4332 trials Discover undiagnosed disease, create program awareness & inform on biomarkers 20

CB 4332: Phase 1/2 - First in human study Study parts Study design +

Phase 1 open-label, single & multiple ascending SQ doses & extended duration proof of concept Single Ascending Doses + Population: CFI-deficient patients (N=up to 12) Proposed starting dose + 0.5 mg/Kg Multiple Ascending Doses (N=up to 9)

Goals + Safety & tolerability + PK characterization Extended treatment to assess + Assessment of complement biomarkers (C3, FB, FBb, proof of concept Bb/FB ratio, iC3b, C3d, C3dg, AP50/AH50) (N=up to 15) + Establish a Recommended Dose Regimen