A phase 1/2 open-label study of KY1044, an anti-ICOS with dual mechanism of action, as single agent and in combination with atezolizumab,F iingu radulte 3 KY 1patients044 PK Pr withofile advanced malignancies Manish R. Patel1, Aung Naing2, Howard Burris III3, Chia-Chi Lin4, Giuseppe Curigliano5, Fiona Thistlethwaite6, Anna Rachel Minchom7, Paolo Antonio Ascierto8, Filippo G. DeBraud9, Michael Cecchini10, Wouter Hanekom11, Richard C.A Sainson11, Rosamund J Wilson11, Sonia Quaratino11 Preliminary PK data on 69 patients demonstrated that the time course was predictable based on non-human primate 1 2 3 4 5 6 Sarah Cannon Research Institute, Florida Cancer Specialists, Sarasota, FL; The University of Texas MD Anderson Cancer Center, Houston, TX; Sarahdat aCannon. The Researchre was aInstitute dose andpro Tennesseeportiona Oncology,l increa sPLLC,e of Nashville,exposu rTN;e w Nationalith inc rTaiwaneasin gUniversity doses bHospital,ased o Taipei,n Cma Taiwan;x. No t aIRCCSrget and me Universitydiated of Milano, Milano, Italy; The Christie NHS Foundation Trust and University of Manchester, Manchester, United Kingdom; 7Drug Development Unit, Royal Marsden Hospital and The Institute of Cancer Research, London, United Kingdom; d8Istitutorug d iNazionalespositio nTumori was IRCCSseen Fondazione after the Pascale, 8 mg dNapoli,ose o Italy;f KY 91University044. of Milan, Fondazione IRCCS Istituto Nazionale del Tumori, Milan, Italy; 10Yale Cancer Center, New Haven, CT; 11Kymab Ltd., Cambridge, United Kingdom No. 2624 Figure 3 Predicted and mean observed KY1044 concentrations across dose levels 0.8 mg (1M) 1000000 0.8 mg (1C) Table 3. Summary of Safety Profile (Safety Set*) Table 5 Observed maximum KY1044 concentrations for Cycle 1 BACKGROUND FigureFigu2.reStudy 2: Studesigndy Design Table 3. Summary of safety profile (safety set*) 0.8 mg Predi cted Table 5. Observed maximum KY1044 concentrations for Cycle 1 Figure 6. RECIST responses of patients treated with combination KY1044 + atezolizumab Q3W Treatment period ≤24 months Follow-up period ≤24 months KY1044 Single agent KY1044 Combination with atezolizumab2.4 mg (2M) PD-L1 (IHC SP263) Patients with advanced/metastatic malignancies/specific tumor indications Schedule of assessments Procedures 100000 (% tumor cells/% immune cells) e.g. NSCLC, HNSCC, HCC, melanoma, cervical, gastric/esophageal, renal, pancreatic & TNBC 2.4 mg (2C) Combination with ● (n=38) [n (%) m] (n=64*) [n (%) m] TNBC-KY1044 2.4 mg KY1044, is a fully human IgG1 anti-inducible T-cell co-stimulator (ICOS) antibody designed to stimulate effector T cells (T ) ) SD PR Eff • Phase 1 escalating doses of KY1044 via IV • Safety follow-up for 90 days after the TEAE Category Human Predicted Monotherapy mean 90/3 HI L and to deplete ICOS regulatory T-cells (T )in the tumor microenvironment. infusion every 3 weeks as single agent or in final dose of study treatment m 2.4 mg Predi cted Human dose azetolizumab mean Reg / TNBC-KY1044 2.4 mg SD PR CR combination with 1200 mg atezolizumab IV g All grades Grade 3/4 All grades Grade 3/4 dose 1 human Cmax observed Cycle 1 25/15 • 3-monthly survival follow-up n ( 8.0 mg (3M) (mg/kg)

observed Cycle 1 ● ICOS is an important co-stimulatory receptor on TEff that also promotes tumor growth due to its high expression on TReg. Phase 1 Dose escalations Completed • Minimum DLT period of 21 days • Recording of all subsequent n 10000 (mg) (µg/mL) human Cmax (µg/mL) Penile SCC-KY1044 24 mg SD PR 1. KY1044 single agent (0.8, 2.4, 8, 24, 80 or 240 mg) Q3W IV o 100/5

HI LOW i KY1044 targets ICOS, acting via a dual mechanism of action by depleting ICOS TReg and stimulating ICOS TEff • Response assessment by RECIST/iRECIST anti-cancer therapies Any TEAEs by CTCAE Grade t 37 (97.4) 231 11 (28.9) 18 59 (92.2) 530 28 (43.8) 59 8.0 mg (3C) human Cmax (µg/mL) 2. KY1044 (0.8, 2.4, 8, 24, 80 or 240 mg) + atezolizumab (1200 mg) Q3W IV a

r HNSCC-KY1044 8 mg SD PR

every 8 weeks for 16 weeks, then every t (Sainsonet al., 2020; see Figure 1). 3/2 12 weeks until disease progression is n 8.0 mg Predi cted e 2 3 confirmed c 0.8 0.01 0.288 0.302 0.334 Pancreatic cancer-KY1044 0.8 mg SD PR Ongoing n NA Phase 1 Enrichment cohorts Related AEs CTCAE Grade ≥3 o -- 0 -- 5 (7.8) 8 24.0 mg (4M)

Figure 1 KY1044 Dual mechanism of action c 1000 Figure 1. KY1044 Dual mechanism of action Solid tumor including preferred indications • Mandatory tumor biopsy at screening and 3 6 0 10 20 30 40 50 60 70 4 2.4 0.03 0.866 0.977 1.06 again on treatment at Cycle 2 Day 8 at 4 24.0 mg (4C) Treatment duration (weeks) Any TEAE leading to study drug 0

regular intervals 1 Y 2 (5.3) 2 -- -- 5 (7.8) 6 24.0 mg Predicted 8 5 6 K 0.1 2.89 3.27 2.95 CR, complete response; HNSCC, head and neck squamous carcinoma; PD-L1, programmed death-ligand 1; PR, partial response; discontinuation • SD – stable disease, PR – partial response, CR – complete response Phase 2 Expansion Ongoing Q3W, every 3 weeks; RECIST, Response• TNBC – Evaluationtriple negative breas tCriteria cancer, SCC – sinqua mSolidous cell caTumors;rcinoma, HNSCC SCC, – head a nsquamousd neck squamous c acellrcinom acarcinoma; SD, stable disease; Tumor indications 100 80.0 mg (5M) 24 0.3 8.68 8.335 6.973 • All patients were treated with KY1044 in combination with atezolizumab Q3W ICOS T agonism: increases Selected indications in which anti-tumor activity was observed in Phase 1 Any related AEs leading to study TNBC, triple negative breast cancer.• AArrowsrrows indicat eindicate patient on trea tpatientment on 16-D eonc-202 0treatment (data cut for this p osonter) 16-Dec-2020 (data cut for this poster) Eff 80.0 mg (5C) • Advanced/metastatic solid tumor malignancies LLOQ 0 -- 1 (1.6) 1 -- 4 3 Patient Case Studies (subject #103) activation (cytokines discontinuation 80 1 29.0 33.8 31.7 Abstract Number 2624 ASCO 2021| CONFIDENTIAL production) of T • Preferred indications: 80.0 mg Predicted Patient case study (subject #103) Eff Figure 2: Study design • NSCLC • Gastric cancer Any related AEs leading to dose 240 3 86.9 133.72 NA • HNSCC • Esophageal cancer 240 mg (6M ) • Adaptive design guided by the Modified Toxicity Probability Interval (mTPI2) method. 10 (2.6) 1 - 4 (6.3) 6 Age, sex, diagnosis Previous therapies vs time-on-treatment in this study – the best response on Target lesion change from BASELINE • • • Dose escalation based on cohorts of at least 3 DLT-evaluable patients. HCC Renal cancer interruption prior treatment is indicated on the chart, e.g., PR for the specific treatment baseline (JUN/2020) • Melanoma • Pancreatic cancer 0 20 40 60 80 100 120 140 160 180 240 mg Predicted Cmax, maximum serum concentration; NA, not applicable. • Enrichment cohorts evaluated additional patients at ≥1 dose level to understand safety, • 59-year-old male with left axillary LN • Cervical cancer • TNBC AE, adverse event; CTCAE, Common Terminology Criteria for Adverse Events; m, numberTime (h )of events; n, number of subjects; 1 • Combination is with atezolizumab2; Cm3ax=m4 axi5mum6 serum concentration; N/A=not applicable. 10% preliminary efficacy and PK/PD relationships. Based on an average human bodyweight of 80 kg; n=4; n=5; n=7; n=8; n=9 HPV-positive metastatic 6L KY1044-CT01 PR Potential for dual mechanism of action 1 2 3 4 5 6 TEAE, treatment-emergent adverse event. *Safety set consists of all patients who take at least one dose of study drug • Based on an average human bodyweight of 80 kg; n=4; n=5; n=7; n=8; n=9 squamous cell carcinoma (agonism and depletion) ● Dose levels <8 mg are associated with partial and transient receptor occupancy (RO) whereas dose levels ≥8 mg are of the head/neck 0% DLT, dose-limiting toxicity; NSCLC, non-small cell lung cancer; HNSCC, head and neck squamous cell carcinoma; HCC, hepatocellular 5L 5-FU DP associated with complete RO. • PD-L1 status at screening carcinoma; IV, intravenous; PD, pharmacodynamic; PK, pharmacokinetic; Q3W, every 3 weeks;Abstra cRECIST,t Number 2Response624 ASCO 202 1Evaluation| CONFIDENTI ACriteriL a 4L Carbop latin and Paclitaxel/nab- PR -10% Table 4. Preferred terms of related AEs by frequency (safety set*) (SP263): % tumor Paclitaxel in Solid Tumors; TNBC, triple negative breast cancer. Table• 4 CPTreCfAeEr r-eCdo Tmemrmosn oTfe rMmoinsot lForgeyq Cureitnetr iRae floart Aedv AeErsse b Eyv eFrnetsq;u AeEn -cyA d(Svaerfesety E Svent)t; TEAE - Treatment Emergent Adverse Events • Figure 4. ICOS receptor occupancy* cells/% immune cells 3/2 * Safety Set consists of all patients who take at least one dose of study drug -20% ICOS TReg depletion: releases KY1044 Single agent (n=38) KY1044 Combination with atezolizumab (n=64) Figure 4 ICOS receptor occupancy* 3L Cetuximab + Cisplatin DP CYCLE 3/DAY 8 • Allocation: KY1044 8 mg (AUG/2020) inhibition of TEff cells Partial/transient receptor occupancy Preferred term All [n (%) m] Grade ≥3 [n (%) m] Preferred term All [n (%) m] Grade ≥3 [n (%) m] Abstract Number 2624 ASCO 2021| CONFIDENTIAL + atezolizumab 1200 mg -30% Partial receptor occupancy 2L Nivolu mab DP 0.8 mg 2.4 mg Q3W RESULTS Abstract Number 2624 ASCO 2021| CONFIDENTIAL (some fluorescent signal) -42% Infusion-related Infusion-related ) -42% s PR -40% 5 (13.2) 5 0 22 (34.4) 24 0 l 1L Cisplatin + Docetaxel + 5-FU

l

reaction reaction e

c

Monotherapy

y

y ● KY1044-CT01 (ClinicalTrials.gov Identifier: NCT03829501) is a first-in-human study evaluating the safety, r

t 0 5 10 15

r -50%

e Table 1. Patient disposition by cohort and dose o Combination Screening C3D8 C10D1 Decreased appetite 3 (7.9) 4 0 Pyrexia 9 (14.1) 9 0 Treatment duration (months) 2020-06-05

pharmacokinetics (PK), pharmacodynamics (PD) and preliminary anti-tumor activity of KY1044 as single agent and m Dosed m (+ 1200 mg atezolizumab)

o

e

t KY1044 5-FU, fluorouracil; DP, disease progression; PR, partial response

y in combination with atezolizumab in patients with advanced/metastatic malignancies.Abstract Num b er 2624 ASCO 2021| CONFIDENTIAL m KY1044 KY1044 Dose-limiting toxicity c Abstract Number 2624 ASCO 2021| CONFIDENTIAL

4

KY1044 dose p Arrow indicates patient was maintaining response of PR at the data cut for this abstract (16-Dec-2020) Fatigue 3 (7.9) 4 0 Lymphopenia 8 (12.5) 13 2 (3.1) i

D

● Single agent Combination with atezolizumab during dose escalation h Labelled anti-ICOS Using longitudinal blood samples and tumor biopsies, we aim to correlate KY1044 target engagement levels with C Complete/prolonged receptor occupancy

C (in mg) (overlapping

%

(n=38) (n=64) (n=31 single agent/n=27 combination) (

m

PD properties (e.g., dual mechanism of action) in the tumor microenvironment and the circulation (see poster 2626 Complete receptor epitope) 240 mg

o m 8 mg 24 mg 80 mg

r Diarrhea 3 (7.9) 3 0 Pruritus 6 (9.4) 7 0 e f CxDx = timepoint

occupancy (no signal) ASCO 2021). M CONCLUSIONS

s 0.8 4 5 0/0 i 4 C = Cycle s ICOS

D

y

l ● The study consists of Phase 1 dose escalation and enrichment cohorts and a Phase 2 part, the Phase 1 dose C D = Day

a

+

Nausea 3 (7.9) 3 0 Fatigue 6 (9.4) 6 0 n 2.4 5 20 0/0 S ● KY1044 is considered well tolerated as single agent and in combination with atezolizumab in patients with escalation part has been completed and the Phase 1 enrichment cohorts and Phase 2 are ongoing, see Figure 2. A

O

C

I advanced/metastatic solid tumors. 8 9 21 0/0 m,• numberSafety Se oft c oevents;nsists of an,ll pnumberatients w hofo tsubjectsake at leas t one dose of study drug ectives OBJECTIVES *Safety• n=n usetmb econsistsr of subje cofts ;all m= patientsnumber o fwho even ttakes at least one dose of study drug ● The maximum tolerated dose was not reached; the maximum administered dose was 240 mg as single agent and 24 8 9 0/0 80 mg in combination with atezolizumab. Summary of KY1044safety profile Visit Primary Abstract Number 2624 ASCO 2021| CONFIDENTIAL + ● Most of the KY1044-related AEs in the single agent cohorts were Grade ≤2; there were no Grade ≥3 related AEs 80 7 9 0/0 • Full target engagement on ICOS CD4Mem ≥ dose level 3 (8 mg) ● To characterize the safety and tolerability of KY1044 as single agent and in combination with atezolizumab and ● There were few treatment interruptions due to treatment-related adverse events (AEs) and no KY1044 dose • Each line represents a single subject in the single agent cohorts, and only 7.8% of all TEAEs in the combination cohorts were considered related to study *Please refer to Poster 2626 + + + + − − to identify the recommended doses for future studies. 240 5 NA 0/NA reductions due to AEs. • ICOS CD4 mem = ICOS CD3 CD4 FoxP3 CD45RA treatment. ● No treatment-related AEs resulted in discontinuation of study treatment in the KY1044 single agent cohorts, Left panel describing the assay format for indirect assessment of ICOS RO. Peripheral blood mononuclear cells were ● Only one patient in the combination cohort (2.4 mg KY1044 + atezolizumab) discontinued treatment due to Secondary Abstract Number 26+24 ASCO 2021| CONFIDENTIAL NA, not applicable and one event of myositis led to discontinuation of study treatment in the combination cohorts. collected at four different timepoints (pre and post dosing during the first two cycles). ICOS CD4 memory cells were immune-mediated myositis. ● To evaluate the preliminary anti-tumor activity of KY1044 as single agent and in combination with atezolizumab. defined as ICOS+CD3+CD4+FoxP3−CD45RA−. The Anti-ICOS staining antibody used for Chipcytometry targets the ● Infusion-related reactions (IRR) were the most frequent related AEs; all IRR were Grade 1 or Grade 2, were extracellular domain of ICOS and competes with KY1044. The absence of signal post dosing was not due to cell ● Treatment duration ≥16 weeks was observed in 24% (9/38) and 27% (17/64) patients in the single agent and ● To characterize the PK profile of KY1044 as single agent and in combination with atezolizumab. amenable to treatment interruption/standard therapies (antihistamine, paracetamol with few requiring steroids), TableTable 2.2. Pa Dosetient D escalationemographics aandnd D enrichmentisease Characte cohorts:ristics demographics and disease characteristics depletion (right panel) but to the presence of the saturated ICOS receptor by the dosed KY1044. Dose levels 1 and 2 combination cohorts, respectively. and mainly occurred during Cycle 1 when no prophylaxis was allowed. Exploratory are associatedFi withgu partialre 5 and D transienturatio ROn whereas on t doserea levelstm >8enmgt are a nassociatedd pe rwithce completentage RO c (morehan datage from b●aDosesel iproportionalne in tu increasesmor ins KY1044ize concentrations were observed. KY1044 Combination with on poster 2626, ASCO 2021). ● To assess the PD effect of KY1044 as single agent and in combination with atezolizumab in tumor tissue and KY1044 Single agent ● Serious AEs were reported in 10 subjects (26.3%) treated with KY1044 single agent and 23 subjects (35.9%) ● PK/PD analysis showed complete ICOS receptor saturation on circulating CD4 memory T cells at 8 mg and above atezolizumab treated with KY1044 in combination with atezolizumab. Most of the events were related to the disease under peripheral blood (see poster 2626 ASCO 2021). (n=38) (see poster 2626, ASCO 2021). (n=64/65)* study; only two suspected unexpected adverse reactions were reported up to 16-Dec-2020: Figure (5.A Duration) on treatment and percentage change from baseline in tumor(sizeB) ● Preliminary biologic and clinical data support the dual mechanism of action of ICOS agonist and intratumoral NA=not applicable ● METHODS Sex: female/male, n (%) 20 (52.6)/18 (47.4) 40 (62.5)/24 (37.5) Grade 2 IRR reported as medically important event T depletion. Spider plots showing Reg ● Grade 5 immune-related event of myositis (cause of death was due to myositis and disease progression). Key inclusion criteria Median age (years) 64.5 63 tumor growth or ● A range of KY1044 doses (0.8–240 mg) have shown biologic/PD and objective responses (including a patient with ● Histologically documented advanced/metastatic malignancies with measurable disease by Response Evaluation Indications, n (%) Abstract Number 2624 ASCO 2021| CONFIDENTIAL Figure 3. KY1044 PK profile shrinkage from prior anti-PD-(L)1 exposure and low PD-L1 expression at screening). Criteria in Solid Tumors (RECIST) 1.1 (non-measurable disease is allowed only in Phase 1). baseline in a cohort ● Promising activity has been observed in difficult to treat indications. NSCLC 1 (2.6) 1 (1.5) Predicted and mean observed KY1044 concentrations across dose levels 0.8 mg (1M) of patients dosed ● Prior therapy with anti-programmed death-(ligand) 1 – PD-(L)1 – inhibitors is allowed provided any toxicity attributed 1000000 0.8 mg (1C) with KY1044 single to prior anti-PD-(L)1-directed therapy did not lead to discontinuation of therapy. HNSCC 1 (2.6) 4 (6.2) 0.8 mg Predicted agent (top) or REFERENCE ● Eastern Cooperative Oncology Group performance status 0 or 1. HCC 2 (5.3) 3 (4.6) Figure 5 Duration on treatm2e.4 mng (2tM )and percentage change from baseline in tumor size KY1044 with 100000 atezolizumab ● Must have a site of disease amenable to biopsy, and be candidate for tumor biopsy, according to the treating Esophageal cancer 2 (5.3) 7 (10.8) ) ● Sainson RCA, Thotakura AK, Kosmac M, et al. An Antibody Targeting ICOS Increases Intratumoral Cytotoxic to Regulatory T-cell

L 2.4 mg (2C)

institution’s guidelines. m (bottom). Patients Ratio and Induces Tumor Regression. Cancer Immunology Research. 2020;8(12):1568–1582. Gastric cancer 1 (2.6) 4 (6.2) / 2.4 mg Predicted g are color coded to

n

( Key exclusion criteria 8 mg (3M)

Melanoma 2 (5.3) 7 (10.8) n 10000 correspond to the

o

i (A) (B) ● t 8 mg (3C) dose of KY1044 DISCLOSURES Symptomatic central nervous system (CNS) metastases, or CNS metastases that require local CNS-directed therapy. a

Renal cancer 4 (10.5) 2 (3.1) r

t

n 8 mg Predicted received. MRP: Consulting or Advisory Role - Pharmacyclics/Janssen, /EMD Serono; Speaker’s Bureau – Exelixis, Genentech/Roche, Taiho Pharmaceutical, Celgene; Honoraria –

● Severe hypersensitivity reactions to other monoclonal or excipients. e Cervical cancer 3 (7.9) 6 (9.2) c Pfizer, Pharmacyclics, Bayer, Janssen Oncology, Genentech. AN: Consulting/Advisory – Novartis, CytomX Therapeutics, OncoSec, STCube Pharmaceuticals Inc.; Travel, n 1000 24 mg (4M) ● Out-of-range laboratory values as defined in the protocol for renal and hepatic function or hematology parameters. o Accommodation, Expenses - ARMO BioSciences; Research Funding - NCI, EMD Serono, MedImmune, Atterocor, Amplimmune, ARMO BioSciences, Karyopharm Therapeutics,

c TNBC 1 (2.6) 9 (13.8)

4 24 mg (4C) Incyte, Novartis, Regeneron, Merck, Bristol-Myers Squibb, Pfizer, CytomX Therapeutics, Neon Therapeutics, Calithera Biosciences, TopAlliance BioSciences Inc, Healios, Lilly,

● Clinically significant heart disease and/or QT prolongation. 4

0 Kymab, PsiOxus Therapeutics, Arcus Biosciences, NeoImmuneTech, ImmuneOncia, Surface Oncology, Jeffrey Modell Foundation, Chao Physician-Scientist Awards. HB:

Pancreatic cancer 9 (23.7) 10 (15.4) 1 24 mg Predicted Employment - HCA Healthcare; Leadership - HCA Healthcare; Stock/Ownership Interests – HCA Healthcare. CCL: Consulting or Advisory Role – Novartis, Boehringer Ingelheim, ● Active autoimmune disease or a documented history of autoimmune disease. Y K Abstract Number 2624 ASCO 2021| CONFIDENTIAL Other 12 (31.6) 11 (16.9) 100 80 mg (5M) Blueprint Medicines, Daiichi Sankyo; Travel, Accommodation, Expenses – Lilly, Daiichi Sankyo, BeiGene, Novartis; Honoraria – Novartis, Roche, Daiichi Sankyo, Lilly. GC: ● Systemic steroid therapy or any immunosuppressive therapy (≥10 mg/day prednisone or equivalent). LLOQ Consulting or Advisory Role - Roche/Genentech, Pfizer, Novartis, Lilly, Foundation Medicine, Bristol-Myers Squibb, Samsung, AstraZeneca, Daiichi Sankyo, Boehringer Ingelheim, 80 mg (5C) GlaxoSmithKline, Genetics; Speaker’s Bureau –Roche/Genentech, Novartis, Pfizer, Lilly, Foundation Medicine, Samsung, Daiichi Sankyo, Seagen; Travel, Accommodation, ● Missing 0 (0) 1 (1.5) Expenses – Roche/Genetech, Pfizer; Honoraria – Ellipses Pharma. FT: Consulting/Advisory - Bristol-Myers Squibb, Octimet, Achilles Therapeutics, Evelo Therapeutics, Common Terminology Criteria for Adverse Events (CTCAE) v5 ≥Grade 2 toxicity due to prior anti-cancer therapy. 80 mg Predicted NSCLC - Non-small cell lung cancer; HNSCC - Head and GlaxoSmithKline, Zelluna, T-Knife; Travel, Accommodation, Expenses – GlaxoSmithKline, Zelluna; Other Relationship – iMatch; Honoraria – Bayer. ARM: Consulting or Advisory ≥4 Prior anti-cancer therapies, n (%) 24 (63.1) 36 (55.4) 10 neck squamous cell carcinoma; HCC - Hepatocellular 240 mg (6M) Role – Janssen Oncology; Travel, Accommodation, Expenses – ; Honoraria - Faron Pharmaceuticals, Bayer, Novartis Pharmaceuticals UK Ltd., Merck, Chugai Pharma; 0 20 40 60 80 100 120 140 160 180 ACKNOWLEDGEMENTS Achieved complete response on any carcinoma. * n=64 for treated data set; n=65 for Research Funding – Seagen. PAA: Consulting or Advisory Role –Bristol-Myers Squibb, Roche/Genentech, Merck Sharp & Dohme, Novartis, Array BioPharma, Merck Serono, 4 (10.5) 7 (10.8) Time (h) 240 mg Predicted Pierre Fabre, Incyte, MedImmune, AstraZeneca, Sun Pharma, Sanofi, Idera, Ultimovacs, Sandoz, Immunocore, 4SC, Alkermes, Italfarmaco, Nektar, Boehringer Ingelheim, Eisai, prior therapy, n (%) demographics (full analysis set) Regeneron, Daiichi Sankyo, Pfizer, OncoSec, Nouscom, Takis Biotech, Lunaphore Technologies, Seattle Genetics; Travel, Accommodation, Expenses – Merck Sharp & Dohme; ● Thank you to the patients and their families for taking part in this study as well as the KY1044-CT01 investigators and Preliminary PK data on 69 patients demonstrated that the time course was predictable based on non-human Stock and Other Ownership Interests – PrimeVax. FGD: Consulting or Advisory Role – Roche, Incyte, Teofarma, EMD SERONO, Bristol-Myers Squibb, Nerviano Medical Sciences, study teams. HCC, hepatocellular carcinoma; HNSCC, head and neck squamous cell carcinoma; NSCLC, non-small cell lung cancer; primate data. There was a dose proportional increase of exposure with increasing doses based on maximum serum Sanofi, Novartis Italy; Honoraria – Roche, Pfizer, Bristol-Myers Squibb, Merck, MSD, SERVIER, Sanofi. MC: Travel, Accommodation, Expenses – AstraZeneca, Eisai, Agios, TNBC, triple negative breast cancer. *n=64 for treated data set; n=65 for demographics (full analysis set) concentration. No target-mediated drug disposition was seen after the 8 mg dose of KY1044. Genentech/Roche; Stock and Other Ownership Interests – Parthenon Therpaeutics; Honoraria – AstraZeneca, Eisa, Agios. WH: Employment – Signal Search Limited, Kymab. ● Funding for this study was provided by Kymab Ltd and atezolizumab was provided by F. Hoffmann-La Roche Ltd. Abstract Number 2624 ASCO 2021| CONFIDENTIAL RCAS: Employment – Kymab. RJW: Consulting or Advisory Role – Kymab. SQ: Employment – Kymab; Stock and Other Ownership Interests – Kymab, Novartis

Abstract Number 2624 ASCO 2021| CONFIDENTIAL Add Copies of this poster obtained through Quick Response (QR) Code are for personal use only Presented at the 2021 ASCO Annual Meeting, Online, 4–8 June 2021 For contact, please email:[email protected] QR and may not be reproduced without permission code from ASCO® and the author of this poster