#18 COMPASS THERAPEUTICS 12214.153] Corporate Presentation February 2023 SRC#2DISCLAIMER This presentation has been prepared by Compass Therapeutics, Inc. ("we," "us," "our," or the "Company"). Statements contained herein are made as of the date of this presentation unless stated otherwise, and this presentation shall not under any circumstances create an implication that the information contained herein is correct as of any time after such date or that information will be updated or revised to reflect information that subsequently becomes available or changes occurring after the date hereof. This presentation includes forward-looking statements regarding our drug candidates, the timing of the start and conclusion of ongoing or planned clinical trials, including the potential impact of the ongoing COVID-19 pandemic on our business, the timing and outcome of regulatory decisions, future availability of clinical trial data, our collaborations for our product candidates and the maintenance of those collaborations, business and results from operations, and other matters. Actual results could differ materially from those contained in any forward-looking statements as a result of various factors, including without limitation: that our drug candidates do not advance in development or result in approved products on a timely or cost effective basis or at all; the cost, timing and results of clinical trials; our ability to manage and mitigate the impact of the ongoing COVID-19 pandemic; that many drug candidates that have completed early-stage trials do not become approved drugs on a timely or cost effective basis or at all; the ability to enroll patients in clinical trials; possible safety and efficacy concerns; regulatory developments; our ability to protect our intellectual property rights, and unexpected costs, charges or expenses that reduce cash runway. Our pipeline programs are in various stages of pre-clinical and clinical development, and the process by which such pre-clinical or clinical therapeutic candidates could potentially lead to an approved therapeutic is long and subject to significant risks and uncertainties. These and other risks and uncertainties that we face are described in our most recent Annual Report on Form 10-K, and in other filings that we make with the Securities and Exchange Commission from time to time. We undertake no obligation to update forward-looking statements as result of new information or otherwise. This presentation also contains estimates and other statistical data made by independent parties and by us relating to market size and growth and other data about our industry. This data involves a number of assumptions and limitations, and you are cautioned not to give undue weight to such estimates. In addition, projections, assumptions, and estimates of our future performance and the future performance of the markets in which we operate are necessarily subject to a high degree of uncertainty and risk. This presentation concerns drugs that are under clinical investigation, and which have not yet been approved for marketing by the U.S. Food and Drug Administration (FDA). It is currently limited by Federal law to investigational use, and no representation is made as to its safety or effectiveness for the purposes for which it is being investigated. COMPASS THERAPEUTICS 2#3Corporate Highlights We are a clinical stage biotech company developing antibody therapeutics for cancer LEAD ASSETS CORE SCIENCE RESOURCES COMPASS THERAPEUTICS CTX-009: DLL4 x VEGF-A bispecific antibody CTX-471: CD137 agonist antibody CTX-8371: PD-1 x PD-L1 bispecific antibody Stitch MabsTM platform designed to identify synergistic bispecific antibodies Common Light Chain technology enables multi-specificity and manufacturability Pre-clinical discovery 8 Cash runway into 2026 (Dec 2022: $187M in cash & marketable securities, $80M PIPE Nov 2022) Funded by leading life-science investors -25 FTES based in Boston, MA with experienced leadership team 32#4Focused Pipeline with Multiple Value Inflection Points Lead Optimization IND Enabling Pre-Clinical Phase 1b Clinical Phase 2 Clinical Program CTX-009 CTX-471 CTX-8371 Undisclosed Target COMPASS THERAPEUTICS DLL4 x VEGF-A CD137 PD-1 x PD-L1 Autoimmune/ Oncology Discovery BTC Colorectal Ovarian / Other CD137 agonist (monotherapy) CD137 + PD-1 (combination)* Solid Tumors *Clinical collaboration with Merck & Co. Inc., Rahway NJ USA in combination with anti-PD-1 therapy KeytrudaⓇ C Next Milestone Initiate Phase 2/3 in U.S. Q1 2023 Top line data in U.S. Q3 2023 Initiate Phase 2 in U.S. H2 2023 Top line data in U.S. Q4 2023 Submit IND H1 2023 4#5Leadership Team Experienced in Drug Discovery and Development Thomas J. Schuetz, MD, PhD Co-Founder, CEO and Director OrbiMed Healthcare Fund Management TKT COMPASS THERAPEUTICS Senior Executive Team Vered Bisker-Leib, PhD, MBA President and COO Cydan Bristol-Myers Squibb Peter Moesta Interim Head of CMC Bristol-Myers Squibb abbvie Carl L. Gordon, Chairman of the Board | Jon Anderman VP, Head of Legal Biogen Intarcia OrbiMed Healthcare Fund Management Vice Presidents Bing Gong, PhD VP of Protein Sciences Pfizer MERCK Neil Lerner, CPA, MIM VP of Finance PSYCHEMEDICS CORPORATION Johnson & Johnson 5#6CTX-009 DLL4 X VEGF-A bispecific antibody 0#7Overview of CTX-009 Bispecific antibody blocking DLL4 (Notch-1 ligand) and VEGF-A (soluble ligand) ➤ Does not lead to ADCC, Fc inactive ➤ Binds to its targets with 2:2 valency At 10 mg/Kg, CTX-009 has approximately the same VEGF-A capturing ability as bevacizumab (Avastin) The only DLL4 X VEGF bispecific that demonstrated monotherapy activity in the clinic in colorectal and gastric cancer Durable responses in patients with cholangiocarcinoma seen in Phase 1b study of CTX-009 in combination with paclitaxel COMPASS THERAPEUTICS (A) (VEGF) DLL4 Anti-VEGF MoAb (Bevacizumab/Avastin) Dual blockade of DLL4 and VEGF overcomes VEGF resistance VEGF/VEGF-R signaling (VEGF) Decreased tumor vessel formation; Reduced tumor growth DLL4 (B) 8 ensin Anti-DLL4 MoAb DLL4-Notch Signaling Increased vessel formation with poor perfusion; Reduced tumor growth 7#8CTX-009-Vision and Potential 88 Best-in-class DLL4 x VEGF- A bispecific Phase 2/3 nearing initiation with ongoing Phase 2 parallel development in S. Korea and China COMPASS THERAPEUTICS Oncology Has demonstrated compelling activity in the 3rd line and 4th line settings in patients with Cholangiocarcinoma, Colorectal Cancer, Gastric Cancer and Pancreatic Cancer Could become front line therapy in multiple solid tumors Other potential indications based on DLL4 expression such as Ovarian Cancer & Renal Cell Ophthalmology Potential to address AMD and DME based on mechanism Consideration for partnership 8#9CTX-009 Phase 1 Program Summary Phase 1a: dose-escalation monotherapy study N=45: Gastric, CRC, Other Nine dose-escalation cohorts (0.3-17.5 mg/kg) Four dose-expansion cohorts (7.5-15 mg/kg) Phase 1 Results » COMPASS THERAPEUTICS Phase 1b: combination study with chemotherapy N=17: 4 arms 1. CTX-009 10.0 mg/kg + paclitaxel 2. CTX-009 10.0 mg/kg + irinotecan 3. CTX-009 12.5 mg/kg + paclitaxel 4. CTX-009 12.5 mg/kg + irinotecan Safety: well-tolerated; MTD has not been determined Activity: 8 PRs, 6 confirmed by RECIST in 33 advanced solid tumor patients treated Responses as a monotherapy: colorectal and gastric Responses in combination with chemotherapy: cholangiocarcinoma, pancreatic Cholangio ORR= 50%; Clinical benefit rate = 75% with a median duration of response of 9.7 months 9#10Phase 1a CTX-009 Monotherapy (all doses) Tumor Growth (%) 100 80 60 40 20 -20 -40 -60 -75% 48% 40% 39% COMPASS THERAPEUTICS 30% 23% 15% 15% 14% 10% 9% 9% 40 evaluable patients as of February 5, 2021 (All Phase 1 Patients, 0.3-17.5 mpk) 8% 8% 7% 7% 6% 4% 4% 4% 3% 3% 0.3 0.3 12.5 12.5 0.3 2.5 12.5 17.5 12.5 5.0 7.5 7.5 5.0 10.0 15.0 2.5 15.0 12.5 1.0 12.5 12.5 1.0 15.0 17.5 0% 0% 0% Patient (Dosage mpk) 12.5 0.3 5.0 -1% 10.0 5.0 12.5 7.5 1.0 -5% -5% -9% -9% -11% -13% -17% Gastric -20% CRC 2.5 7.5 10.0 12.5 15.0 10.0 12.5 10.0 Other -26% -27% -35% -38% -40% -41% 10#11Phase 1a CTX-009 Monotherapy Data Clinical activity at RP2D dosages (10 and 12.5 mg/kg) All patients (n=16) Colorectal Cancer (n=6) Gastric Cancer (n=8) COMPASS THERAPEUTICS Prior VEGF Targeted Therapy 75% 100% 63% Partial Response (PR) 19% 33% 13% Stable Disease (SD) 50% 33% 63% Clinical Benefit Rate (PR + SD) 69% 67% 75% Median Time to Progression (TTP) (Months) 3.9 6.7 3.9 11#12Phase 1b CTX-009 Combination Study Tumor Growth (%) 50.0% 40.0% 30.0% 20.0% 10.0% 0.0% -10.0% -20.0% -30.0% -40.0% -50.0% -60.0% -70.0% 36.8% COMPASS THERAPEUTICS 22.7% 16.3% 7.4% 0.0% 17 evaluable patients as of November 30, 2021 CTX-009 + paclitaxel or CTX-009 + irinotecan All patients dosed at 10 or 12.5 mg/kg -0.7% -10.4% -12.7% -17.0% -18.3% -19.7% -20.6% -28.0% -31.4% o Gastric CRC -34.9% Cholangio Pancreatic Other -41.4% -61.6% 12#13Phase 1 CTX-009 Safety Data Phase 1a Monotherapy (n=45) Drug-related adverse events observed in > 5% of patients Hypertension* General disorders (fatigue, fever, asthenia, edema, etc.) Nervous system disorders (headache, dizziness) Gastrointestinal disorders (nausea, vomiting, etc.) Pulmonary hypertension Proteinuria Total (n) 17 7 7 6 4 3 Total Grade 3 (%) (n) 38 16 16 13 9 7 7 1 1 2 0 0 Grade 3 (%) 16 2 2 4 0 0 Phase 1b Combination (n=17) Drug-related adverse events observed in > 1 patient Hypertension Nausea Fatigue Neutropenia** Anemia** Thrombocytopenia** Diarrhea Anorexia Proteinuria Pulmonary hypertension (all grade 1) Dyspnea Gingival edema (mucositis) Anal hemorrhage Total (n) 8 8 6 * In clinical trials of bevacizumab, incidence of Grade 3-4 hypertension ranged between 5%-18% (Avastin label). It is typically managed by anti-hypertensive drugs **Labeled Grade 3/4 cytopenia events for concomitant chemotherapy agent: COMPASS THERAPEUTICS Irinotecan: 31.4% neutropenia, 4.5% anemia, 1.7% thrombocytopenia. Paclitaxel: 52% neutropenia, 16% anemia, 7% thrombocytopenia 642 5 5 5 5 4 2 2 Total (%) 47 47 35 5425 35 12 29 29 29 29 24 12 12 Grade 3 (n) 4 1 1 2 3 2 0 0 0 0 0 0 0 Grade 3 (%) 24 6 6 282 12 18 12 0 0 0 0 0 0 0 13#14CTX-009- Phase 1 Clinical Studies Summary Overall Response Rate at the Efficacious Dose (10-12.5 mg/kg) Monotherapy Combination 18.8% ORR (3/16) 23.5% ORR (4/17) COMPASS THERAPEUTICS Clinical Benefit Rate at the Efficacious Dose (10-12.5 mg/kg) Monotherapy 68.8% (11/16) Combination 76.5% (13/17) 14#15Phase 2 CTX-009 Combination Study (S. Korea) Patients with biliary tract cancers after one or two prior therapies Simon 2 Stage adaptive design COMPASS THERAPEUTICS Stage 1 CTX-009 at 10 mg/kg biweekly Paclitaxel 80 mg/m² weekly 3 of 4 weeks N = 21 3 or more PRs Stage 2 CTX-009 at 10 mg/kg biweekly Paclitaxel 80 mg/m² weekly 3 of 4 weeks N = 45 additional patients 15#16Phase 2 CTX-009 Combination Study - Patient Demographics Age Median (years) Gender, n(%) Male Female ECOG performance status, n(%) 0 1 COMPASS THERAPEUTICS 24 Total Patients 61.5 14 (58%) 10 (42%) 13 (54%) 11 (46%) Prior systemic therapies, n(%) 1 2 Prior Gem/Cis regimen BTC subtype, n (%) Intrahepatic cholangiocarcinoma Extrahepatic cholangiocarcinoma Gallbladder cancer Ampullary cancer 24 Total Patients 11 (46%) 13 (54%) 23 (96%) 9 (38%) 3 (13%) 7 (29%) 5 (21%) 16#17Percent tumor decline Phase 2 CTX-009 Data Responses achieved across multiple BTC subclasses. Data as of November 9, 2022 Patient Number 0 -10 -20 -30 -40 -50 -60 1 -1 2 -7 3 -7 4 5 6 7 8 9 10 11 -12 COMPASS THERAPEUTICS -9 Intrahepatic cholangiocarcinoma Extrahepatic cholangiocarcinoma Gallbladder cancer Ampullary cancer -12 -12 -17 -17 -19 11 -20 12 -25 13 -33 2 patients were not evaluable (one missing post baseline scan; one had a scan outside of protocol window) 14 -33 15 -37 16 CONFIRMED PARTIAL RESPONSE -38 17 -41 18 -44 19 ORR = 37.5% CBR = 91.5% -44 20 -48 21 -52 22 -57 17#18CTX-009 Swimmer Plot (November 9, 2022, data cutoff) C1D1 to EOT (Days) 300 0 COMPASS THERAPEUTICS B 58 520 49 78 100 HA 0 93 92 119 119 | 159 183 O 182 175 173 168 200 277 297 287 324 316 O 310 303 O 343 400 500 511 600 580 700 PR SD ◆PD O Death On-going 18#19CTX-009 Phase 2 Results (Median follow-up of 12.1 months) 24 patients enrolled and dosed 1 patient remains on study Endpoint Overall Response Rate (ORR) Stable Disease (SD) Progression Free Survival (PFS) Overall Survival (OS) Duration of Response COMPASS THERAPEUTICS Value (95% CI) 37.5% 54.2% 9.4 m (5.4-11.1) 12.5 m (10.9 - NA) 6.9 m (3.5-NA) Number of previous systemic therapies Pts treated in the 2L [n=11] Pts treated in the 3L [n=13] ORR 7/11 (63.6%) 2/13 (15.4%) 19#20Secondary Endpoints: PFS and OS (as of Nov 9, 2022) Median OS: NA (12.5-NA) ● Median PFS: 9.40 m (5.4-11.1) A 1.0 Survival Probability 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 All T 1 2 2nd line COMPASS THERAPEUTICS 3 4 5 3rd line 6 7 8 9 10 11 12 13 14 Progression Free Survival (months) Number at risk All 24 23 21 20 17 17 10 10 10 10 7 5 2 2 2 2nd line 11 11 10 9 9 9 1 1 3rd line 13 12 11 11 8 8 1 155 155 055 055 122 Group All 2nd line 3rd line 21 2 5 3 1 1 15 16 2 1 1 2 1 1 Median (95% CI) 9.4(5.4-11.1) T 17 1 + Censored 1 0 10.0(5.1-NA) 5.5(3.6-11.1) 18 1 1 T 19 20 0 0 B Survival Probability 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 ● — All 0 1 - 2nd line T 2 3 T 4 5 - T 6 Number at risk All 24 24 23 21 21 21 20 2nd line 11 11 11 11 11 11 11 3rd line 13 13 12 10 10 10 3rd line 7 8 9 10 11 12 13 14 15 16 Overall Survival (months) 19 19 19 17 16 12 10 10 10 9 8 5 8 8 7 Group All 2nd line 3rd line 9 9 9 9 835 633 532 + Censored Median(95% CI) 12.5(10.9-NA) 11.7(9.1-NA) 12.9(5.3-NA) 17 18 2 1 1 1 1 0 1 1 19 20 0 0 % 20#21Treatment-Emergent ≥ Grade 3 Adverse Events (>10% of patients) Phase 2 BTC study of CTX-009 plus paclitaxel Bevacizumab and paclitaxel label information Event Neutropenia Anemia Hypertension Thrombocytopenia 24 total Patients N (%) 20 (83.3%) COMPASS THERAPEUTICS 5 (20.8%) 4 (16.7%) 3 (12.5%) TEAE leading to discontinuation: confusion, embolism, pneumonia (grade 5), biliary fistula, large intestine perforation, blood creatinine increased, and blood urea nitrogen increased Event Neutropenia Hypertension Anemia Thrombocytopenia Bevacizumab (label) 5-18% Additional events: Gl perforation, wound healing complications, Proteinuria, hemorrhage Paclitaxel (label) 52% 16% 7% Additional events: Hypersensitivity reactions, infections, bleeding, neuropathy 21#22How Does CTX-009 Data Compared to Other BTC Studies? FOLFOX (ABC-06) 1 Gem/Cis 2 1L Only 2L Parameter ORR OS PFS Any AE Gr 3/4 AEs Deaths (as Gr 5) AEs leading to discontinuation COMPASS THERAPEUTICS CTX-009 Mixed 2L and 3L N=24 37.5% [64% 2L; 15% 3L] 12.5 m 9.4 m 100% 92% 1 (4%) 25% N=81 5% 6.2 m 4.0 m 99% 60% 10 (12%) ~ 12% 1. Lamarca D, Lancet Oncol 2021; March 30 2. Valle, J. et al., N ENGL J MED, 362; 14 Apr 8, 2010, p. 1273 Oh, D. et al., ESMO Poster 56P 2022 3. N=204 26% 11.7 m 8.0 m 55% 71% 17 (8%) 10% Gem/Cis + Durv 3 Only 1L N=341 26.7% 12.9 m 7.2 m 99.4% 74% 13 (4%) 13% 22#23CTX-009 Interim Phase 2 Study Summary 24 patients with BTC have been enrolled and dosed 10 partial responses (PRs) for a 37.5% ORR in patients treated in the second- and third-line settings (64% ORR of patients treated in the 2nd line setting) Median PFS 9.4 months Median OS 12.5 months Adverse event profile similar to Phase 1 studies COMPASS THERAPEUTICS Other regimens in BTC FOLFOX (NCCN guidelines): 5% ORR in the second-line setting 4.0 month median PFS 6.2 month median OS TOPAZ-1 (Phase 3 study): 26.7% ORR for Gem/Cis/Durvalumab (anti PD-L1) in the first-line setting 23#24Phase 2/3 U.S. BTC Study Design Patients who have received one prior line of therapy 2:1 Randomization COMPASS THERAPEUTICS CTX-009 + Paclitaxel n=100 Paclitaxel n=50 Study Treatment 28 Day Cycles CTX-009 10mg/kg Day 1 and 15 Paclitaxel 80 mg/m² Day 1, Day 8, and Day 15 of every 28 day cycle. Disease Progression per RECIST 1.1, as confirmed by Independent Central Radiology Follow Up Death, Lost to Follow Up, Withdrawal of Consent 24#25CTX-009: BTC Patient Demographics and Current Treatments Incident Cases 1L Treatment Doublet chemo of gemcitabine + cisplatin (ABC-02 study) Or Gemcitabine/cisplatin + durvalumab (recently approved for 1L) US 18,400¹ FOLFOX 5% ORR 0.9 Mos OS A EU5 21,800² 1. NCI Surveillance, Epidemiology, and End Results (SEER) program 2. Delveinsight/company estimates COMPASS THERAPEUTICS 3. International Agency for Research on Cancer/GLOBOCAN Japan Worldwide 14,329² >200,000³ 2L Treatment FGFR2 mutation Pemigatinib (10-15% of CCA) IDH1 mutation Ivosidenib (1-3% of BTC) MSI-H tumors PD-1 Inhibitor (<1% of BTC) Clinical trial 25#26Phase 2 U.S. CRC Study Design COMPASS THERAPEUTICS Simon 2 Stage Adaptive Design Stage 1 Stop Recruitment Stage 2 No n = 37 subjects ORR > 3/37 Yes n = 47 subjects 26#27CTX-009: CRC Patient Demographics and Current Treatments Japan Chemotherapy FOLFOX/FOLFIRI Incident Cases ~50% Metastatic³ 50-70% reach 3L4 1L Treatment Bevacizumab or EGFR inhibitor + chemotherapy US 153,020¹ 38,000-53,000 patients Anti-PD-1 with MSI-H/dMMR mutation ~5% of CRC EU5 1. NCI Surveillance, Epidemiology, and End Results (SEER) program 2. International Agency for Research on Cancer/GLOBOCAN COMPASS 3. L Biller, D Schrag, JAMA 2021 Feb 16 THERAPEUTICS 4. Bekaii-Saab, Clin advances in Hem and Onc, Supp Jan 2021 246,734² 2L Treatment Bevacizumab or EGFR + chemo 148,505² BRAF/EGFR with V600E mutation 5-8% of CRC Worldwide 1,931,590² 3L Treatment Regorafenib ORR 1%, Median PFS 2.0 months Trifluridine/ tipiracil ORR 1-2% Median PFS ~2 months 27#28CTX-009 Development Plans Initiated Q4 2022 Phase 2 study in third- and fourth- line colorectal cancer in the US COMPASS THERAPEUTICS Initiate Q1 2023 Phase 2/3 Randomized BTC study in the US O Initiate H2 2023 Phase 2 study in advanced ovarian or other cancer in the US Evaluating additional indications for CTX-009 both as a monotherapy and in combination with chemotherapy 28#29CTX-471 CD137 monoclonal antibody 0#30CTX-471: Potential Best-in-Class CD137 Agonist CTX-471: next generation CD137 agonist Fully human, IgG4, optimized affinity for agonistic antibody Unique epitope: non-ligand blocking Phase 1 Study Update Monotherapy in post checkpoint inhibitor patients Monotherapy Phase 1a multiple ascending dose study completed Near PR in a patient with mucosal melanoma Prolonged stable disease in two patients with NSCLC MTD defined by immune thrombocytopenia Monotherapy Phase 1b dose expansion study nearing completion 4 PRs observed so far: small cell lung cancer, mucosal melanoma, metastatic melanoma, and mesothelioma ● ● ● COMPASS NOVEL EPITOPE WITH DIFFERENTIATED ACTIVITY OBSERVED IN EXTENSIVE PRECLINICAL DATA* THERAPEUTICS Urelumab, 3H3 CD137 CTX-471 CD137L Utomilumab *Eskiocak, et al. JCI Insight. 2020;5(5):e133647 30#31CTX-471: Partial Response in a Patient with Small Cell Lung Cancer after progression on atezolizumab/chemo and nivolumab >>> 66 y.o. man with advanced SCLC: Carboplatin/etoposide plus atezolizumab first line; nivolumab second line Multiple metastases: Largest mass (RUL Lung) shown below, ~ 4 cm at baseline → 40% total decline Confirmed and durable PR at Month 24 COMPASS THERAPEUTICS Baseline Month 4 Month 8 31#32CTX-471 Clinical Development Plans Phase 1b study fully enrolled Generally well tolerated Four partial responses as a monotherapy agent in the post PD-1/PD-L1 patient population Small cell lung cancer, mesothelioma, and melanoma (two patients) COMPASS THERAPEUTICS Initiating Phase 1b of CTX-471 with KeytrudaⓇ Abbreviated CTX-471 dose escalation into the PD-1 regimen, followed by a cohort expansion Post PD-1/PD-L1 Salvage Study Clinical collaboration with Merck 32#33CTX-8371 PD-1 x PD-L1 bispecific antibody#34Stitch MabsTM Platform was Utilized to Identify CTX-8371 Unexpected synergistic activity of PD-1/PD-L1 combination in bispecific Stitchmab format IFNg (pg/ml) 3000- 2000- 1000- T1 X - Y VS Pembro/Atezo Stitchmab Nivo/Atezo Stitchmab COMPASS THERAPEUTICS Cocktail Pembro + Atezo T2 0 10 pM 0.1 PM Nivo + Atezo Cocktail Mixed lymphocyte reaction (MLR) assay Pembro Common Light Chain bispecifics were generated to test therapeutic hypothesis PD-1 PD-L1 CTX-8371 Our PD-1xPD-L1 bispecifics observed to outperform PD-1 blockers in T-cell activation assay 1400¬ 1200- 1000- 800- 600- 200 0.0001 Plate 1 0.001 0.01 0.1 1 Ab concentration (nM) 10 PD-1xPD-L1 v1 PD-1xPD-L1 v2 Keytruda Nivolumab Isotype Control No Ab Control 34#35CTX-8371: Differentiated MoA Leads to Enhanced T-Cell Activation Converting PD-1 positive T cells into PD-1 negative T cells PD-1 blockers release brake but don't directly promote T-cell activation APC or Tumor cell T-cell PD-L1 PD-1 -1- COMPASS THERAPEUTICS PD-L1 CD80 CD28 + + " + APC or Tumor cell PD-1 T-cell CTX-8371 activates T-Cells Through Multiple MOA's Significant reduction in cell surface PD-1 due to receptor shedding Bridging of PD-1 expressing T- cells with PD-L1 expressing APC's or tumor cells + + + + ## PD-L1 X PD-L1 Increased pool of free CD80 able to engage costimulatory receptor CD28 CD80 + + ↓↓ CD28 35#36CTX-8371 Pre-Clinical Poof of Concept Activity in MC38-hPD-L1 model implanted in hPD-1/hPD-L1 transgenic mice Average Tumor Volume (mm³) 1500- 1000- 500- 2000- 1500- 1000- 15 500- IgG1 IC Atezolizumab 2000₁ 1500- JIL 1000- 500- 10 20 30 40 50 18 21 27 24 Days after tumor cells inoculation Endpoint Responders COMPASS THERAPEUTICS HHHH 0/8 0- 0 10 20 30 40 50 НА НЕН IgG1 IC Atezolizumab → KeytrudaⓇ CTX-8371 30 20001 1500- 1000 500 CTX-8371 0- 0 10 20 30 40 50 Days post treatment 2000 1500- 1000- 500- Keytruda Ⓡ 0 10 20 30 40 50 %Tumor Growth Inhibition [ 100- 50- -200 -400- *** Mann-Whitney test IgG1 IC Group CTX-8371 Atezolizumab IgG1 IC Keytruda CTX-8371 ** p=0.0001 * p=0.027 % Cured 62.5 KeytrudaⓇ Atezolizumab 12.5 0 25 Tumor free / total 5/8 1/8 0/8 2/8 36#37CTX-8371: Development Status IND enabling activities NHP dose range finding study completed → PD-1 shedding confirmed in vivo Manufacturing campaign completed Pre-IND meeting completed Toxicology studies underway COMPASS THERAPEUTICS O Phase 1 study planning Multiple ascending dose, dose-escalation study 5 doses planned: 0.1, 0.3, 1.0, 3.0, and 10 mg/kg Post PD-1 or PD-L1 patient population PD-1 shedding on peripheral T cells was confirmed in NHP IND submission targeted for H1 2023 Potential for proprietary combination regimens with CTX-009 and CTX-471 37#38Compass Therapeutics Summary#39Program Summary >>> >>> »»>> CTX-009 Novel DLL4 x VEGF-A bispecific antibody with both combination and monotherapy activity Phase 1: Dose response established - responses in multiple indications BTC Phase 2 results: 24 patients: 37.5% ORR (2L/3L), 63.6% (2L), median PFS 9.4 months, OS 12.5 months; initiating Phase 2/3 randomized study CRC Phase 1 monotherapy activity in 3rd line: initiated Phase 2 in 4Q 2022 CTX-471 Potential best-in-class CD137 agonist antibody with monotherapy activity Phase 1 monotherapy study fully enrolled 4 partial responses (PRs) in post PD-1 population: small cell lung cancer, metastatic melanoma, mucosal melanoma, mesothelioma CTX-471 in combination with KEYTRUDA® study was initiated in 4Q 2022 CTX-8371 Next generation PD-1 x PD-L1 bispecific antibody Discovered with our Stitch Mabs TM screening platform Superior activity to commercial PD-1 and PD-L1 inhibitors in preclinical studies Unique MOA - enhances T-cell activation COMPASS THERAPEUTICS 39#40Key 12 Month Milestones COMPASS THERAPEUTICS COMPASS THERAPEUTICS Q4 2022 Initiated CTX-009 US CRC Phase 2 Study Q4 2022 Completed the ongoing CTX-471 Phase 1b study ↑ Q1 2023 Initiating CTX-009 US BTC Phase 2/3 Study Q4 2022 Initiated CTX-471 plus PD-1 Study H1 2023 CTX-8371 IND filing H2 2023 Top line data from CTX-009 US CRC Phase 2 Study H2 2023 Initiate CTX-009 U.S. Ovarian /other Phase 2 Study 9 H1 2024 Top line data from CTX-009 US Phase 2/3 BTC Study H2 2023 Initiaite CTX-8371 Phase 1 Study 40