Forward looking statements 1 & 2 October 2018 Nassim Usman, Ph.D. President & CEO This presentation includes forward-looking statements that involve substantial risks and uncertainties. All statements, other than stateme

CATALYST BIOSCIENCES December 18th 2018

Research & Development Day Exhibit 99.1

Forward looking statements 1 & 2

October 2018 Nassim Usman, Ph.D. President & CEO This presentation includes forward-looking statements that involve substantial risks and uncertainties. All statements, other than statement of historical facts, included in this presentation are

forward-looking statements. Examples of such statements include, but are not limited to, the potential benefits of subcutaneous administration of dalcinonacog alfa (formerly CB 2679d/ISU304) and marzeptacog alfa (activated), the potential for

long-term dosing of dalcinonacog alfa to maintain FIX activity in the high-mild hemophilia range, statements relating to Catalyst's clinical trial timelines, including plans for a Phase 2b clinical trial of dalcinonacog alfa, including

initiation in the first quarter of 2019 and presentation of data at ISTH, plans for a Phase 3 trial of dalcinonacog alfa, plans for the completion of the ongoing clinical trial of marzeptacog alpha (activated) and presentation of data at EAHAD and

ISTH and for a Phase 3 trial of marzeptacog alfa (activated), and the potential market opportunities for these products. Actual results or events could differ materially from the plans and expectations and projections disclosed in these

forward-looking statements. Various important factors could cause actual results or events to differ materially from the forward-looking statements that Catalyst makes, including, but not limited to, the risk that trial initiation or enrollment may

be delayed and that ongoing or future trials may not achieve their endpoints, that subsequent clinical trials will not replicate the results from earlier clinical studies on small numbers of patients, that potential adverse effects may arise from

the testing or use of Catalyst's products, including the generation of antibodies or inhibitors, the risk that costs required to develop or manufacture Catalyst's products will be higher than anticipated, the risk of competition from

other hemophilia treatments, including those in development, Catalyst's ability not to infringe third party intellectual property rights, and other factors described in the "Risk Factors" section of Catalyst's Quarterly

Report on Form 10-Q for the quarter ended September 31, 2018, which was filed with the Securities and Exchange Commission on November 1, 2018. Forward looking statements in this presentation speak only as of the date hereof. Catalyst does not assume

any obligation to update any forward-looking statements, except as required by law.

Catalyst Biosciences: CBIO We are

working to establish a new standard of care in hemophilia prophylaxis by developing highly potent subcutaneous treatments that improve the quality of life for patients with hemophilia with inhibitors, acquired hemophilia & hemophilia

Investment highlights ~134 worldwide

patents - CBIO retains full ownership of all compounds Experienced team Well funded $129 M cash (Q3 2018) Novel subcutaneous compounds with orphan drug designation FVIIa & FIX SQ efficacy clinically demonstrated Market: $3.4B in annual

sales FIX FVIIa 2018

Life with hemophilia Hemophilia B Rare

disorder, FIX deficient, mostly inherited but can be caused by a spontaneous mutation Causes spontaneous bleeding, mostly into joints, resulting in disabling joint damage Hemophilia A or B - inhibitors A complication in factor replacement

therapy that neutralizes the treatment 30% of Hem A (FVIII) patients and 5% of Hem B (FIX) patients develop inhibitors Patients are at high risk for hemorrhagic stroke and premature mortality Acquired Hemophilia Rare disorder, occurs spontaneously,

bleeding caused by anti-FVIII nAbs Currently treated with immunosuppressants + IV bypass agents (FVIIa, FEIBA or Obizur ) Unmet need to adequately treat & prevent re-bleeds

Market Hemophilia B, FIX: $1.2B market

Sources: WFH Annual Global Survey, GlobalData, Roche, Novo Nordisk, Aptevo, SOBI, Bioverativ. *Hemlibra had global sales of $58M in 1H 2018 FVIIa & Bypassing Agents: $2.2B market In 2017 over 2,400 US and EU5 patients were treated with

FVIIa and bypassing agents for hemophilia with inhibitors, acquired hemophilia and factor VII deficiency In 2017 over 6,000 US and EU5 hemophilia B patients were treated with recombinant FIX BeneFIX 2017 Sales Alprolix Idelvion (est.)

Ixinity Rixubis (est.) 2017 Sales NovoSeven FEIBA (est.) Obizur (est.)

Available treatments Regular

intravenous (IV) infusions are necessary to maintain higher clotting levels IV treatments are very unpleasant and time-consuming Inconvenience affects compliance, outcomes and quality of life Especially difficult for pediatric patients & their

The Catalyst Biosciences solution Our

highly potent solution: +Quick & simple subcutaneous injection - allows for self-administration including in pediatric patients +Much higher & stable factor levels - keeps patients at safe levels for much longer

The new standard in hemophilia

prophylaxis Patients in high mild range are protected from spontaneous bleeds The concept of prophylactic treatment is to keep severe & moderate hemophilia patients in the high mild range Our subcutaneous treatment has the ability to build up

over time, offering long-term stability in clotting levels Mild Hemophilia Protection from spontaneous hemarthrosis when activity >12% Normal clotting levels Moderate Hemophilia 15-20 bleeds/year IV treatment Severe Hemophilia ~30 bleeds/year SQ

Pipeline Hemostasis programs:

Hemophilia with inhibitors FVIIa: Marzeptacog alfa (activated) "MarzAA" (formerly CB 813d/PF-05280602 ) Hemophilia B FIX: Dalcinonacog alfa "DalcA" (formerly CB 2679d/ISU304) Universal pro-coagulant FXa: CB 1965a Dry AMD: anti-C3

protease CB 2782 Anti-complement programs: Research Preclinical Phase 1/2 Phase 2/3 Commercial rights CBIO CBIO CBIO CBIO

Team VP, Business Development

Jeffrey Landau, M.B.A. President & CEO Nassim Usman, Ph.D. Chief Medical Officer Howard Levy, M.B.B.Ch., Ph.D., M.M.M. Chief Financial Officer Fletcher Payne SVP, Technical Operations Andrew Hetherington, M.B.A. 26 years in biotech 20 years in

biotech 18 years in hematology 26 years in biotech 16 years in biotech VP, Translational Research Grant Blouse, Ph.D. 12 years in biotech

CATALYST BIOSCIENCES December 18th

2018 Dalcinonacog alfa

Dalcinonacog alfa, a novel clinical

stage SQ FIX product candidate differentiated from IV market leaders: Simpler, less painful, small dose SQ enhances pharmacokinetics Potential to maintain continuous protective levels Disruptive to all current intravenous products Especially well

suited for children Three point mutations in two loops within the FIX protein: Catalytic activity increased Affinity for activated factor VIII increased Resistance to inhibition by antithrombin improved Best-in-class high-potency recombinant FIX

product 22-fold more potent than BeneFIX in man Orphan Drug Designation in US & EU Dalcinonacog alfa R318Y R338E T343R Resistance to antithrombin Increased FVIIIa affinity & procoagulant activity

Retrospective immunogenicity

assessment A comprehensive assessment of immunogenicity addressed several key hypotheses "Considering our global and regional in silico analysis alongside whole protein and peptide in vitro experiments we find the risk that wildtype

FIX and therapeutic candidate DalcA will create or contribute to anti-therapeutic immune response to be minimal." Key Hypotheses Tested HLA and genotype are risk factors The DalcA molecule is inherently immunogenic Drug product quality or

formulation induce ADAs ISRs increased the risk of ADAs

DalcA has low immunogenicity &

should proceed to P2b Moving forward with dalcinonacog alfa after preclinical immunogenicity risk assessment In Silico and in vitro risk is equivalent to that of competitors such as BeneFIX No significant ISRs were observed in a 7d monkey PK/ tox

study Drug product characterization shows DalcA comparable to other rFIX products Clinical, regulatory and immunology KOLs provided positive opinions Back in the clinic: Preclinical immunogenicity profile is similar to commercial FIX

Dalcinonacog Phase 1/2 open label

design DalcA IV vs BeneFIX IV BeneFIX IV 70 IU/kg DalcA IV 70 IU/kg DalcA IV 70 IU/kg DalcA IV 70 IU/kg DalcA IV 70 IU/kg DalcA SQ 70 IU/kg DalcA SQ 140 IU/kg 9 daily-doses DalcA SQ 140 IU/kg DalcA SQ 140 IU/kg 6 daily-doses DalcA IV to SQ crossover

ascending dose cohorts 2 - 3 DalcA multi-dose SQ DalcA IV + multi-dose SQ Cohort 1 (n=3) Cohort 2 (n=3) Cohort 3 (n=3) Cohort 5 (n=5) Cohort 6 (n=2) Subcutaneous treatment of hemophilia B 3-month interval

40 35 30 25 20 15 10 5 0 0 1 2 3 4 5

days FIX activity level % 6 7 8 9 13 11 10 12 Moderate 1-5% Mild 5-40% Severe <1% + Cohort 6: C5-01-S01 C5-01-S02 Cohort 5: C4-01-S06 C4-01-S05 C4-01-S07 C4-01-S01 C4-01-S02 IV Peak 75% FIX activity Phase 1/2: Cohort 5 & 6 FIX activity

results 6/7 patients had trough levels >12%, suf cient to protect against spontaneous joint bleeds

Phase 1/2: Cohort 6 FIX nAb

development timeline Time course of neutralizing antibody development after prior exposure in Cohort 5

The DalcA drug product is not

inherently immunogenic In Silico & In vitro Immunogenicity (Molecule is inherently immunogenic) HLA Typing / Immunogenicity (Certain HLA types increase risk of ADAs) DP Quality Characterization (Drug quality induces ADAs) DP Formulation

Characterization (Formulation induces ADAs) Same as BeneFIX & RIXUBIS Same profile as WT FIX & BeneFIX Restrict genotype & potential at risk HLAs No consistent ISRs in NHP 7-day SQ study Investigation Hypothesis Conclusion SQ Dosing

(Route of Administration induces ADAs) No issues with MarzAA with >325 days dosing & Idelvion with 15 exposure days

Subject ID DRB1 DPB1 DQA1 DQB1

Genotype Phenotype C5-01-S01 03:01 04:01 02:01 02:01 03:01 05:01 02:01 03:01 128G>A Arg43Gln: propeptide C5-01-S02 01:01 13:01 02:01 04:01 01:01 01:01 05:01 06:01 128G>A Arg43Gln: propeptide C4-01-S02 01:01 08:01 02:01 05:01 01:01 01:01 05:01

06:01 1150C>T Arg384Term: Truncation C4-01-S07 08:01 12:01 02:01 05:01 03:01 05:01 03:01 03:01 1045G>T Gly349Term: Truncation C2-03-S01 04:01 13:01 04:01 05:01 01:01 03:01 03:01 06:01 880C>T Arg294Term: Truncation C3-02-S03 11:01 15:01

05:01 05:01 01:01 05:01 03:01 06:01 1219T>G Cys407Gly: Protease C3-02-S04 09:01 09:01 02:01 05:01 03:01 03:01 03:01 03:01 127C>T Arg43Trp: propeptide The two subjects in cohort 6 that developed the nAbs are cousins and have the same genotype

Genotype is an Arg to Gln mutation at amino acid -4 (defective propeptide cleavage site) Only common HLA type is DPB1 02:01 HLA and genotyping HLA and genotyping of 7/11 Korean subjects in the P1/2 trial nAb

Preclinical toolkit for evaluation

of immunogenicity Effector T-Cell Antigen Presenting Cell Designed Peptides T-Cell Proliferation DC T-Cell Assay Uptake

Preclinical toolkit for evaluation

of immunogenicity Effector T-Cell Antigen Presenting Cell MAPPS Peptide Presentation In Silico Analysis DalcA DalcA Processing Display T-Cell Proliferation DC T-Cell Assay Uptake

The in silico immunogenicity

assessment shows low risk In Silico immunogenicity risk assessment Overall immunogenicity risk is low and on par with BeneFIX Factor IX protein sequence contains fewer putative Class II T cell epitopes than would be expected in a randomly generated

sequence of similar length of -42.54 (BeneFIX -41.65) These scores fall in the lower range of the scale, indicating a weak potential for immunogenicity BeneFIX & DalcA Immunogenicity Threshold

DalcA shows a similar in silico risk

as BeneFIX at R318Y DalcA BeneFIX In Silico immunogenicity assessment at the R318Y site

DalcA shows a similar risk as

BeneFIX at R338E In Silico immunogenicity assessment at the R338E site DalcA BeneFIX

DalcA shows a similar risk as

BeneFIX at T343R In Silico immunogenicity assessment at the T343R site DalcA BeneFIX

Peptides from DalcA show low

immunogenicity risk % Responding Donors DC-T cell stimulation: Peptides Overall immunogenicity risk profile for the individual peptides is low and on par with BeneFIX Peptides covered all three amino acid substitutions and selected from in silico

data Peptides identified in MAPPS experiment have partial or full overlap with tested peptides R318Y R338E T343R R338E R338E/T343R BeneFIX derived peptide DalcA derived peptide Control peptide or protein

Peptides from DalcA show low

immunogenicity risk Response Index DC-T cell stimulation: Peptides Overall immunogenicity risk profile for the individual peptides is low and on par with BeneFIX Peptides covered all three amino acid substitutions and selected from in silico data

Peptides identified in MAPPS experiment have partial or full overlap with tested peptides R318Y R338E T343R R338E R338E/T343R BeneFIX derived peptide DalcA derived peptide Control peptide or protein

The DalcA drug product shows low

immunogenicity risk Responding Donors DC-T cell stimulation: Drug Product Overall immunogenicity risk profile risk is low and on par with BeneFIX Formulation buffer was at background 8/52 responders to DalcA and 5/52 responders to BeneFIX (52/52

responders for both controls) No significant HLA association was evident

Response Index DC-T cell

stimulation: Drug Product Overall immunogenicity risk profile risk is low and on par with BeneFIX Formulation buffer was at background Clinical therapeutics with low risk have Response Index values (RI) between 0.1 and 0.4 Consistent with range of

responses observed for other clinical grade therapeutics with low risk (less than an RI of 0.4) No significant HLA association was evident The DalcA drug product shows low immunogenicity risk

Presented peptides are comparable

for DalcA & BeneFIX TEGYRLAENQKSCEPA Gla EGF1 EGF2 SPD 46 1 47 83 84 125 415 126 DVDYVNSTEAETILDN TEQKRNVIRIIPHHNYNAAINK AAINKYNHDIALLELDEPL ELDEPLVLNSYVTPICIADK IADKEYTNIFLKFGSGYVS GRSALVLQYLRVPLVDRAT RSTKFTIYNNMFCAGFH AMKGKYGIYTKVSRYVN No

peptides identified from Gla domain or EGF 1 D1581 D1714 D1837 D1842 D1858 D1863 D1867 D1869 D1871 D1894 D1895 D1896 Donors BeneFIX HLA-DR

Presented peptides are comparable

for DalcA & BeneFIX TEGYRLAENQKSCEPA Gla EGF1 EGF2 SPD 46 1 47 83 84 125 415 126 DVDYVNSTEAETILDN TEQKRNVIRIIPHHNYNAAINK AAINKYNHDIALLELDEPL ELDEPLVLNSYVTPICIADK IADKEYTNIFLKFGSGYVS GYSALVLQYLRVPLVDRAT ESTKFRIYNNMFCAGFH AMKGKYGIYTKVSRYVN