Exhibit 99.1 Corporate Presentation April 2023

Forward-Looking Statements Certain statements contained in this presentation, other than statements of historical fact, are forward-looking statements, within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements can be identified by the use of words such as “believes,” “expects,” “ hopes,” “may,” “will,” “plan,” “intends,” “estimates,” “could,” “should,” “would,” “continue,” “seeks,” “pro forma,” or “anticipates,” or other similar words (includin g their use in the negative), or by discussions of future matters. These forward-looking statements include, without limitation, statements regarding the timing, progress and results of preclinical studies and clinical trials for our product candidates; our product development plans and strategies; plans and expectations with respect to regulatory filings and approvals; the potential benefits and market opportunity for our product candidates and technologies; expectations regarding future events under collaboration and licensing agreements, as well as our plans and strategies for entering into further collaboration and licensing agreements; expectations regarding our future financial position and results of operations; and our expected cash runway; and expected benefits of our reprioritizing. Forward-looking statements are subject to risks and uncertainties that could cause actual results to differ materially and historical results should not be considered as an indication of future performance. These risks and uncertainties include, among others, risks inherent in the development and regulatory approval process for novel therapeutics; the fact that future preclinical and clinical results/data may not be consistent with initial or preliminary results/data or results/data from prior preclinical studies or clinical trials; potential delays in development timelines, including delays in clinical trials; the potential impact of the COVID-19 pandemic; our reliance on third parties for development and manufacturing activities; changes in competitive products or in the standard of care; the risk of early termination of collaboration agreements; the risk that our proprietary rights may be insufficient to protect our product candidates or that we could infringe the proprietary rights of others; the fact that we will need additional capital and such capital may not be available on acceptable terms or at all; and changes in laws and regulations. Other factors that may cause our actual results to differ from current expectations are discussed in our filings with the U.S. Securities and Exchange Commission, including the section titled “Risk Factors” contained therein. Caution should be exercised when interpreting results from separate trials involving separate products or product candidates. There are differenced in the clinical trial design, patient populations, follow-up times, and the product candidates themselves. These forward-looking statements are based on information available to, and expectations of, Ambrx as of the date of this presentation. Ambrx disclaims any obligation to update these forward-looking statements, except as may be required by law. All trademarks and registered trademarks set forth herein are the property of their respective owners. AMBRX | Corporate Presentation 2 © 2023 Ambrx Biopharma Inc. All rights reserved.

Antibody Drug Conjugates (ADCs) – Targeted Cancer Cell Killing Design ADCs Antibody Drug Conjugates (ADCs) are composed of 1) a cancer killing chemotherapeutic payload, 2) an antibody-targeting a cancer cell and 3) a linker connecting the antibody to the payload Problem ADCs that have weak linkage/conjugation can prematurely release their toxic payload, which can damage healthy tissues and lead to an unfavorable toxicity profile Our Solution Ambrx’s proprietary chemical conjugation technology prevents the premature release of its cancer killing toxic payload Benefits Ambrx’s technology incorporates the advantages of highly specific targeting mAbs securely linked to a highly potent chemo cancer killing payload to achieve targeted and efficient elimination of cancer cells AMBRX | Corporate Presentation 3

Ambrx: Multiple Potential Value Drivers Two Antibody Drug Conjugate (ADC) Programs Delivering Data in 2023 ARX517 Anti-PSMA ADC: ARX788 Anti-HER2 ADC: Safety and efficacy data focusing on prostate Safety and efficacy data focusing on breast cancer cancer expected this year from APEX-01, expected this year from ongoing US clinical trials ongoing dose escalation Phase 1 US clinical trial I-SPY 2.2, and Pan-Tumor-01 Engineered Precision Biologics (EPBs) Platform Spun out of Scripps Research, Ambrx is the pioneer of the expanded genetic code technology platform for incorporation of synthetic amino acid (SAA) into proteins at any selected site in industry standard cell lines SAAs allow engineered precision biologics (EPBs) with site-specific, homogenous and stable conjugation, overcoming limitations of traditional conjugation technologies Portfolio of US patents, pending applications, and exclusive patent licenses, which cover our core technology platforms and products AMBRX | Corporate Presentation 4

Ambrx Oncology Pipeline Candidate Indications Trial Setting (Name) Preclinical Phase 1 Phase 2 Next Anticipated Milestone(s) Ambrx Sponsored Oncology Programs Neo Adjuvant BC I-SPY 2.2 Complete enrollment Preliminary data update – 2024 HER2+ mBC post- ARX788 Breast-03 TM ENHERTU Initiate post-ENHERTU study Anti-HER2 ADC Numerous Cancer Types Pan Tumor 01 Preliminary data update – 2H 2023 including HER2+ mBC (enrollment closed) ARX517 Advanced Prostate Cancer APEX-01 Preliminary data update – 2H 2023 Anti-PSMA ADC Partnered Program with NovoCodex US IND cleared ARX305 Renal Cell & other cancers -- Preliminary partner data update – Anti-CD70 ADC 2023 Focused Pipeline on Proven Targets in Established Markets AMBRX | Corporate Presentation 5

Anticipated 2023 Clinical Milestones ARX517 ARX517 ARX788 ARX788 Anti-PSMA ADC Anti-PSMA ADC Anti-HER2 ADC Anti-HER2 ADC Pan-Tumor-01 APEX-01 Phase1 Pre-clinical data Initiate signal- ARX305 ARX305 preliminary data to be preliminary data to and TIP poster for finding study in Anti-CD70 ADC Anti-CD70 ADC presented at a be presented at a APEX-01 post- medical conference medical presented at ENHERTU NovoCodex Pre-clinical data conference, AACR in April patients Phase 1 to be presented targeting ESMO preliminary at AACR in April data in renal cell cancer Q2 2023 2H 2023 AMBRX | Corporate Presentation 6

ADC Golden Age, Pfizer-Seagen $43B Buyout at a 20X Revenue Multiple Given the difficulty in developing a biosimilar, ADCs are a therapeutic modality that command a significant premium Other examples include: • Gilead’s acquisition of Immunomedics for $21B (2021) • Multi-billion Daiichi Sankyo and AstraZeneca collaboration AMBRX | Corporate Presentation 7

ARX517 Anti-PSMA ADC for Prostate and Other Cancers

ARX517 is the Only ADC Targeting PSMA in Prostate Cancer Created with proprietary SAA technology AS269 • Fully humanized anti-PSMA monoclonal antibody (mAb) produced in CHO cells with site-specific incorporation of SAA for conjugation • Contains two (2) drug-linkers (AS269, a tubulin polymerization inhibitor) per mAb, Binding Site specific a DAR2 ADC domain conjugation • Highly stable linkage – site-specific conjugation via oxime chemistry Superior ADC stability design offers an advantage over previous ADC competitors that have failed due to conjugation instability First-in-Human APEX-01 Phase 1 dose escalation ongoing https://clinicaltrials.gov/ct2/show/NCT04662580?term=arx517&draw Light Chain =2&rank=1 Heavy Chain Potential to Become First-in-Class & Best-in-Class PSMA-ADC AMBRX | Corporate Presentation 9

ARX517 Addresses Stability Issues of Prior ADCs Targeting PSMA Name PSMA-ADC MLN-2704 MEDI-3726 ARX517 Company Progenics, Seagen Millenium/Takeda MediImmune, ADCT Ambrx Antibody fully human IgG1 J591 (humanized) J591 (humanized) J591 (humanized) Payload MMAE DM1 PBD dimer (SG3199) AS269 Payload cell permeability yes yes yes No DAR ~4 ~4 ~1.8 2 Conjugation Cysteine Lysine Cysteine pAF site-specific, oxime Linker cleavable (val-cit) cleavable (disulfide) cleavable (val-ala) noncleavable Linker stability unstable unstable unstable stable Stage discontinued (Ph2) discontinued (Ph1) discontinued (Ph1) Ph1 Ongoing neutropenia, neuropathy, Myelosuppression, skin tox, Tox (SAE) 2 deaths at 2.5m/kg peripheral neuropathy vascular leakage None Thrombocytopenia, vascular DLT neutropenia, neuropathy peripheral neuropathy leakage, ↑ALT/GGT N/A T1/2 (day) ~2 ~2.5 (2 in monkey) < 2 ~14 in Monkey at 9mpk Ongoing P1 dose escalation Highest Dose (mg/kg) 2.8 ~12.5 0.3 currently at 2.9 mg/kg instability: high [serum instability: high [serum DM1], short Major liability MMAE], short ADC t1/2 ADC t1/2 PBD-mediated toxicity N/A Petrylak et al, The Prostate. Milowsky et al, Urol Oncol. 2016, DeBono et al, Clin Cancer Reference 2019:1-10. 34(12): 530.e15-21. Res. 2021, 27(13):3602-3609. AACR2023 Comparison based on a review of published literature. For illustrative purposes only. No head-to-head trials with ARX788 have been conducted. AMBRX | Corporate Presentation 10

Ambrx’s Proprietary Site-Specific Conjugation Designed to Produce Stable, Homogenous ADCs Ambrx’s SAA Conjugation Cysteine Conjugation Lysine Conjugation 80 Sites 32 Sites 2 Selected Sites SAA = Synthetic Amino Acid Maximum tolerated dose Maximum tolerated dose Maximum tolerated dose Less Narrow Therapeutic Window Larger Therapeutic window Narrow Therapeutic Window Minimum effective dose Minimum effective dose Minimum effective dose SAA conjugation can overcome the inherent limitations of conventional ADC conjugation methodologies that utilize naturally occurring cysteines and lysine payload conjugations which negatively impact reactivity, stability and selectivity* *Bioconjugate Chem (2008), 19(8), 1673-1683 AMBRX | Corporate Presentation 11

Eligibility Criteria ARX517 - APEX-01 Phase 1 Trial Design Must have had a least two We are here 2.9 mg/kg C8 FDA approved treatments for Dose Escalation prostate cancer one of the Q3W Dosing, i3+3 Design 2.4 mg/kg C7 (16-36 Adult Patients) following: 2.0 mg/kg C6 - PSA progression by a MTD or RP2D C5 1.7 mg/kg minimum of 2 rising PSA Expansion values or C4 1.4 mg/kg - Radiographic progression C3 1.07 mg/kg Dose Expansion by RECIST v 1.1 or in metastatic-castration resistant prostate C2 0.64 mg/kg cancer (mCRPC) - Disease progression by the (Up to 40 Subjects) C1 0.32 mg/kg presence of new bone lesions. Preliminary Data* • Promising early safety and efficacy data observed • No drug-related SAEs, no DLTs for all Cohorts evaluated Objectives • In Cohort 6 (2.0 mg/kg dose), confirmed PSA responses in the first 3 patients with a greater than 50% reduction in Primary: safety, tolerability PSA levels, with two patients having a reduction in PSA >90% and one patient with soft tissue measurable disease experiencing a confirmed RECIST v1.1 partial response & RP2D • > 30% PSA reductions observed in one or more patients in all previous cohorts starting at 0.64 mg/kg Secondary: radiographic • Patients were heavily pretreated, with a median of five prior lines, including lutetium Lu 177 vipivotide tetraxetan response, PSA Response (PLUVICTO) (PSA30, PSA50, PSA90) AMBRX | Corporate Presentation 12 * Company Press Release, February 16. 2023

The Case for ARX517 in mCRPC PSMA is highly expressed (89%) in metastatic castration resistant prostate cancer (mCRPC), as well as neovasculature of various solid tumors PSMA is a clinically validated target and an established market for mCRPC ® • PLUVICTO has validated the PMSA as an effective prostate cancer target Widespread adoption and clinical application of PLUVICTO may be challenging due to the limitations 1 on utilization of radiotherapy As an infused product, and not a radioligand, we believe an opportunity exists for ARX517 • ARX517 does not require referrals to radiation oncology / nuclear medicine or specialized facilities for administration • ARX517 can be utilized by community medical oncologists 1 Market research Sept. 2022 done by First Principle AMBRX | Corporate Presentation 13

ARX788 Anti HER2 ADC for HER2+ Metastatic Breast Patients in Post ENHERTU Settings

ARX788 - Potential to Become ADC of Choice for Post-ENHERTU Patients Fully humanized anti-HER2 mAb incorporated a synthetic amino acid at the optimized location on each of the two heavy chains to enable AS269 precision conjugation • DAR=2: Contains two (2) drug-linkers (AS269, a tubulin polymerization inhibitor) per mAb Binding Site specific domain conjugation Highly stable, site specific & homogenous conjugation design features ( strong anchor ) • Highly stable linkage using a highly specific and stable oxime chemistry • Increased drug delivery efficiency & specificity, reducing drug usage • Minimize off-target toxicity: extremely low payload concentration in blood circulation, limiting potential for systemic toxicity ARX788 data demonstrated activity in breast cancer • Breast-01 (Phase 1) and Breast -02 (Phase 3) demonstrated that ARX788 can Light Chain deliver compelling responses in a heavily pretreated HER2 positive metastatic Heavy Chain breast cancer patients in China • Data presented at SABCC demonstrated that ARX788 had activity post- ® KADCYLA and therefore may work post-ENHERTU • Preliminary anti-tumor activity observed in a small number post-ENHERTU, post- KADCLYA and HER2 low patients in Breast-03 and Pan-Tumor-01 in U.S. AMBRX | Corporate Presentation 15

ENHERTU Changed the Breast Cancer ADC Landscape, but 24.2% of Patients on ENHERTU Progress within 12 Months Lack of post-ENHERTU data supporting the effectiveness of KADCYLA and/or ® TUKYSA potentially creates a new large market opportunity with no standard of care https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(22)02420-5/fulltext AMBRX | Corporate Presentation 16

Breast-01 (China) and PanTumor-01(US/AU) † Confirmed ORR with ARX788 in patients whose disease is Breast-01 resistant or refractory to prior HER2 treatment (trastuzumab, 69 adult patients in China, ORR was 65.5%, DCR was 100% † ADCs, TKIs, and bispecific antibodies) and the median PFS was 17.02 months Prior anti-HER2 therapy* Confirmed ORR ARX788 was well tolerated with most adverse events (AEs) Trastuzumab containing regimens* 19/29 (66%) being Grade 1 or 2 and manageable, low systemic toxicity HER2 ADCs (T-DM1, DX126-262, A166, BAT8001, and HS630) regimens** 4/5 (80%) was observed, no DLT or drug-related deaths occurred HER2 TKIs (lapatinib, pyrotinib, neratinib, AST-1306, and Hemay-022) regimens 15/23 (65%) ARX788 has robust anti-tumor activity, generally good Both HER2 ADC and HER2 TKI regimens 3/4 (75%) tolerance, circulating stability and unique pharmacokinetic Bispecific antibodies (KN026 and M802) containing regimens 3/4 (75%) profile in HER2-positive metastatic breast cancer patients Data cut-off: June 30, 2021 who had progressed on prior anti-HER2 therapies † † Pan-Tumor-01 Pan-Tumor-01 (US/AU) demonstrated comparable clinical response to Breast-01 with ORR at 67% and DCR 100% at 1.5mg/kg (N=3) † Breast-01 conducted in China by Ambrx’s partner, NovoCodex Biopharmaceuticals and published Clinical Cancer Research (2022) 28 (19): 4212–4221 (Zhang, et. al.) https://doi.org/10.1158/1078-0432.CCR-22-0456 † † Presented: San Antonio Breast Cancer Conference 2022 AMBRX | Corporate Presentation 17

Breast-01 Demonstrated ARX788 Has Competitive Activity Potential in the HER2+ mBC ADC Landscape HER2+ ADCs in Breast Cancer Efficacy Landscape* KADCYLA ENHERTU ENHERTU ARX788** RC48*** SYD985 (TDM1) (T-DXd) (T-DXd) Pop 2L 2L 3L Median 5L Median 4L 3L ORR 35.0% 78.5% 69.7% 65.5% 41% 27.8% DOR 23.8m 36.6m 19.6m 14.4m - PFS 6.8m 28.8m 17.8m 17.0m 6m 7m Source DB03 DB03 DB04 Breast-01* Zhang Wang Saura In a heavily pretreated patient population, ARX788 has demonstrated robust ORR *Based on a review of published literature. For illustration purposes only. No head-to-head trials with ARX788 have been conducted. **Breast-01 conducted in China by Ambrx’s partner, NovoCodex Biopharmaceuticals AMBRX | Corporate Presentation 18 ***SeaGen acquired rights for RC48 for $200M as well as $2.4B in milestones

Breast-02 Pivotal Phase 3 Study of ARX788 for the Treatment of HER2+ mBC Achieved Positive Results • Breast-02 is a randomized, controlled, pivotal Phase 3 clinical trial of ARX788 for the treatment of HER2+ patients with locally advanced or mBC in China • The study enrolled 441 HER2+ BC patients who were previously treated with taxane and trastuzumab • 1:1 randomization to ARX788 or the control (lapatinib combined with capecitabine) • Primary endpoint was PFS based on Blinded Independent Review Committee (BIRC) assessment • Interim analysis was conducted by an Independent Data Monitoring Committee (IDMC) when two-thirds (2/3) of the PFS events occurred • IDMC determined that the study met its pre-specified interim primary efficacy endpoint with statistical significance, demonstrating a greater PFS benefit compared to the control • NovoCodex has submitted a communication application to seek marketing approval in China pending discussion with National Medical Products Administration (NMPA) AMBRX | Corporate Presentation *Breast-02 conducted in China by Ambrx’s partner, NovoCodex Biopharmaceuticals 19

ARX788 Provided a Clinical Benefit to Post KADCYLA (T-DM1) Patients Key Takeaways* r r A r s . Statistically significant reduction in tumor size in patients 0.00 0 previously treated with T-DM1 who had disease progression 0 4/7 patients also previously received HER2 TKI treatment 20 0 Confirmed (ORR) was 57.1% (4/7 pts) and an unconfirmed 0 ORR of 71.4% (5/7 pts) 0 (DCR) was 100% (7/7 pts) 0 .2 . Treatment with ARX788 remains ongoing with the median time 0 . 0 of ARX788 therapy of 7.2 months 0 0 ARX788 was generally well-tolerated, and AEs were 0 .00 00 manageable with the most common treatment-related AEs 00 .00 2 being Patient Counter Bar Color Sub ect nrolled https://s27.q4cdn.com/912984828/files/doc_presentations/2022 /12/_2022-SABCS-ACE-Breast-03_Ambrx.pdf * San Antonio Breast Cancer Conference, 2022 AMBRX | Corporate Presentation 20 Change from baseline (

Summary of ARX788 Safety Data (All Cohorts) ARX788 (All Treated Population) Number of patients (%) Breast-01 Gastric-01 Pan-Tumor-01 (N=67) (N=69) (N=30) All AEs (regardless of causality) ( 00 ​ 61 (91.0%) 29 (96.7%) Treatment-related AEs (any grade) 67 (97.1%) 48 (71.6%) 28 (93.3%) All A s ≥ Grade and Grade A s 16 (23.2%) 23 (34.3%) 10 (33.3%) Treatment-related Grade 3 and Grade 4 AEs 8 (11.6%) 8 (11.9%) 4 (13.3%) All SAEs 8 (11.6%) 17 (25.4%) 7 (23.3%) Treatment-related SAEs 2 (2.9%) 5 (7.5%) 2​ ( . Treatment-related AEs leading to discontinuation 3 (4.3%) 6 (9.0%) 2 ( . ​ Treatment-related Deaths 0 0 0​ Data cut-off: Dec-14-2021 for Breast-01 (China), Dec-14-2021 for Gastric-01 (China), Dec-13-2021 for Pan-Tumor-01 (US/AUS) AMBRX | Corporate Presentation 21

Systemic Toxicity: ARX788 (Breast Cancer and Pan-tumor) is Significantly Lower than ENHERTU (USPI)* ARX788 (1.5 mg/kg Breast cancer, Pan-Tumor population) ENHERTU (5.4 mg/kg)* Number of patients (%) Number of patients (%) Breast-01 (N=29) Pan tumor-01 (N=17) N=234 mBC All Grades Grade 3 or 4 All Grades Grade 3 or 4 All Grades Grade 3 or 4 Nausea 2 (6.9%) 0​ 5 (29.4%) 1 (5.9%) 79% 7% Vomiting 2 (6.9%) 0​ 3 (17.6%) ​ ( . 47% 3.8% Constipation 4 (13.8%) 0​ 1 (5.9%) 0​ 35% 0.9% Diarrhea 1 (3.4%) 0​ 1 (5.9%) 0​ 29% 1.7% Neutropenia 5 (17.2%) 0 1 (5.9%) 0​ 62% 16% Decreased WBC 5 (17.2%) 0​ 1 (5.9%) 0​ 70% 7% Thrombocytopenia 4 (13.8%) 1 (3.4%) 1 (5.9%) 0​ 37% 3.4% Anemia 5 (17.2%) 0​ 2 (11.8%) 0 31% 7% Fatigue 7 (24.1%) 0​ 5(29.4%) 0 59% 6% Neuropathy 0 0​ 1 (5.9%) 0​ <10% <2% Dizziness 1 (3.4%) 0​ 0 0​ 10% 0 Headache 1(3.4%) 0​ 2 (11.8%) 0​ 19% 0 *Data from ENHERTU USPI, Reference ID: 4732117, 01/2021 Based on a review of published literature. For illustration purposes only. No head-to-head trials with ARX788 have been conducted. AMBRX | Corporate Presentation 22 Data cut-off : Jun-30-2021 for Breast-01, Jul-14-2021 for Gastric-01; Jul-12-2021 for Pan tumor-01

Mechanisms to Potentially Overcome Resistance to ENHERTU Even in low HER2 target environment, ARX ’s engineered stability designed to ensure that it always delivers a fully loaded ADC sufficient to kill the cancer cell ENHERTU treatment can lead to reduction of HER2 target The payload of ARX788 is ENHERTU uses a DNA- Over multiple engineered to deter multiple targeting toxic agent (TOPOi), Tumor cells have exposures to a specific drug resistance (MDR), while ARX788 has a different both active and payload, tumor cells thereby avoiding active passive mechanisms payload, a potent tubulin can develop resistance to eliminate toxic elimination, and is non-cell inhibitor, which can overcome to the payload, which payloads permeable, which prevents TOPOi resistance can reduce efficacy passive escaping AMBRX | Corporate Presentation 23

Rationale for Planned Phase 2 Study of ARX788 in HER2+ mBC post-ENHERTU • Completed study Breast-01 (Phase 1) demonstrated robust response rate HER2+ metastatic breast cancer (mBC) in China and encouraging responses observed in Pan-Tumor-01 in the Amend existing Breast-03 US protocol to conduct a small − Data published in Clinical Cancer Research (2022) & ASCO signal seeking study in US in (2021) ~40 patients • Preliminary observations from Breast-03 and Pan-Tumor-01 US • No more than 3 prior lines of studies in small number of patients provide rationale for anti- therapy and recent assessment of tumor activity in post-ENHERTU, post-KADCYLA and HER2 low HER2+ status patients • Dosing 1.5 mg/kg Q3W − Post-KADCYLA data presented at SABCC (2022) • Primary endpoint: ORR; • Breast-02, a randomized, controlled, pivotal Phase 3 clinical Secondary endpoints: PFS, OS, trial of ARX788 for the treatment of HER2+ patients with locally DoR advanced or mBC in China met its pre-specified interim primary efficacy endpoint with statistical significance • Mechanisms to Potentially Overcome Resistance to ENHERTU AMBRX | Corporate Presentation 24

Post-ENHERTU Market Could Be a Billion Dollar Opportunity Assuming price is in line with TRODELVY 01 Estimated drug treated patients in 3L+ (~$25,000 for 4 wks) and similar PFS (~ 6 mo) equates to $150,000 per patient per course (3L or later) HER2+ BC: ~10,000 to >14,000, depending on source • 9,800 drug-treated patients per Decision 1 Assuming 50% lower pricing ex-US, this translates Resource Group (DRG) 02 into a potential market opportunity greater than $1B • >14,000 patients per HER2 competitors in annual peak sales Roche and AstraZeneca estimates of patient populations published in their investor materials (September, 2020 (Roche) and June, 2022 (AstraZeneca)) Further upside is possible if ENHERTU is approved in 03 1L (ongoing Destiny-Breast 09 study), which may open opportunity for ARX788 in the 2L setting 1 AMBRX | Corporate Presentation Market research on file, Sept. 2022, First Principle 25

ARX788 Selected for Inclusion in Prestigious I-SPY 2.2 A Phase 2 Trial to Treat HER2-Positive Breast Cancer in the Neoadjuvant Setting The adaptive trial assesses developing targeted agents to combine them with less toxic chemotherapeutic regimens or to completely replace cytotoxic chemotherapy ARX788 will be assessed as a single agent in patients with HER2-positive early-stage breast cancer in the neoadjuvant setting I-SPY 2.2 is designed to quickly analyze encouraging experimental therapies and detect the most effective ones in specific patient subgroups depending on molecular characteristics Enrollment commenced in May 2022 I-SPY 2.2 - A Responsive Adaptive Trial to Prioritize Promising Investigational Agents AMBRX | Corporate Presentation 26

Financial Information Highlights Financial Information Cash, cash equivalents and investments as of 12/31/22: $101.3 MM Additional Cash Raised via ATM (Q1 2023): $78 MM Outstanding Shares (ADS*): 55.2 MM Clean Balance Sheet: No outstanding warrants or debt AMAM (NASDAQ) (March 20, 2023) Market Capitalization: $533 MM Average Daily Trading Volume: ~0.7M shares Share Price $9.66 Cash Runway into 2025 * As of March 20, 2023, the Company had 386.5 million ordinary shares outstanding (including ordinary shares in the form of ADSs), equivalent to approximately 55.2 million ADSs. AMBRX | Corporate Presentation 27

Ambrx Leadership Shawn Zhang, PhD Ying Buechler, PhD Sandra Aung, PhD D ni O’ nn r, JD Sonja Nelson, CPA Chief Scientific Officer Chief Technology Officer Executive VP, Head of Clinical CEO and President CFO & COO AMBRX | Corporate Presentation 28

Appendix: Preclinical Pipeline and Other Programs Engineered Precision Biologics & Site-Specific Conjugation

Ambrx Preclinical Oncology Pipeline and Non-Oncology Programs Candidate Indications Preclinical Phase 1 Phase 2 Key Highlights TROP2 is over-expressed in a variety of solid tumors. ARX ’s payload with differentiated MOA Numerous Cancer Types may address potential resistance to TOPOi ADCs. Stable linker and potent cell-impermeable ARX111 including TNBC, PDAC payload class (MTI) for reduced off-target toxicity and enhanced on-tumor efficacy, particularly in Anti-TROP2 ADC and NSCLC TOPOi ADC-resistant settings, as well as improved in vivo anti-tumor activity in CDX model vs. benchmark. Numerous Cancer Types HER2-targeted delivery of immune-stimulatory payload, TLR7 agonist, a potent tumor antigen- ARX622 including breast, gastric dependent immune stimulator. ARX622 is designed to engage and boost the natural immune Anti-HER2 TLR7 and ovarian system, delivering a sustained whole-body anti-tumor effect. Agonist ISAC* ARX102 is a PEGylated IL-2 protein with virtually no α receptor binding (alpha -OFF) designed to Numerous Cancer Types abrogate the severe adverse effects associated with IL-2 therapy, thereby to increase the ARX102 IND enabling including renal cell and therapeutic window. ARX102 is the only modified IL-2 produced in mammalian cells which can studies completed Alpha-off pIL-2 melanoma confer full functionality to deliver IL-2’s intended immuno-oncology effect on T-effector cells. IND enabling studies are completed. Non-Oncology Programs FGF21 is a non-mitogenic hormone and an important regulator of energy metabolism. Multiple Non-alcoholic clinical trials, including Phase 1, Phase 2 and Phase 2b, have been performed and demonstrated: i) ARX618 Phase 2b Steatohepatitis (NASH) clear safety profile and treatments were well tolerated; and ii) anti-fibrotic and anti-NASH activity PEGylated FGF21 demonstrated on biopsy as well as non-invasive assessments. Relaxin pathway has multiple positive activities in the heart, vasculature & kidney for treatment of ARX721 Phase 1/2 Acute Heart Failure chronic heart failure. Three clinical trials performed, one Phase 1 and two Phase 2. FA-Relaxin Novel Strategy Using EPBs to Fight Cancer and Other Diseases * ISAC – immune stimulating antibody conjugate AMBRX | Corporate Presentation 30

Engineered Precision Biologics – EPBs ENGINEERED PRECISION BIOLOGICS Engineering proteins in Precise site-selection of a Biologics, which include a living cells, both bacterial stable and predictable wide variety of formats and mammalian, by attachment point in the (mAbs, cytokines, CD3 incorporating synthetic protein for payload Fabs), and delivering a amino acids (SAAs) into conjugation resulting in wide variety of payloads those proteins in very a both stability and >90% (cytotoxins, immune- site-specific manner homogeneity stimulators, etc.) AMBRX | Corporate Presentation 31

Ambrx’s Proprietary Site-Specific Conjugation Produces Highly Stable and Homogenous ADCs Expanded genetic code creates engineered proteins by site-specifically incorporating SAAs Enables precise modification and orthogonal chemistry for stable conjugation Enables novel drug design and potential wider therapeutic index Manufacturing scalability. ReCODE (E. coli) - 50,000L: Imrestor (bG-CSF)/ EuCODE (CHO) - 2,000L: Multiple mAbs/ADCs AMBRX | Corporate Presentation 32