Exhibit 99.1 Unaudited IFRS Condensed Consolidated Interim Financial Statements as of and for the three months ended March 31, 2023. Condensed Consolidated Interim Statement of Operations 2 Condensed Consolidated Interim Statement of Comprehensive Loss 3 Condensed Consolidated Interim Balance Sheet 4 Condensed Consolidated Interim Statement of Changes in Equity 5 Condensed Consolidated Interim Statement of Cash Flows 6 Notes to the Condensed Consolidated Interim Financial Statements 7 ADC Therapeutics SA Co ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 20-F (Mark One) ☐ REGISTRATION STATEMENT PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 OR ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2022 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 OR ☐ SHELL COMPANY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 19 ...

ZYNLONTA Development and Approvals - ZYNLONTA received conditional approval in Europe and the UK for relapsed or refractory DLBCL, with a launch expected in Q2 2023[5] - ZYNLONTA's Phase 3 LOTIS-5 trial in second-line DLBCL and Phase 2 LOTIS-9 trial in first-line DLBCL are ongoing, aiming to expand its use in earlier lines of therapy[6] - ZYNLONTA® received FDA approval for targeting CD19 in relapsed or refractory large B-cell lymphoma (LBCL) after two or more lines of systemic therapy[46] - LOTIS-5, a Phase 3 confirmatory trial for ZYNLONTA, is underway to verify clinical benefits under the FDA accelerated approval program[46] - ZYNLONTA received conditional marketing authorization from the European Commission for relapsed or refractory DLBCL in December 2022, with commercialization expected to commence in Europe[61] - ZYNLONTA received FDA accelerated approval on April 23, 2021, for relapsed or refractory large B-cell lymphoma after two or more lines of systemic therapy[70] - ZYNLONTA's Phase 3 confirmatory trial (LOTIS-5) is enrolling 350 patients with relapsed or refractory DLBCL, with 20 patients in the safety run-in showing an ORR of 75% and CR of 40%[64][73] - LOTIS-5 trial aims to evaluate ZYNLONTA combined with rituximab compared to standard immunochemotherapy, with primary objective being progression-free survival (PFS)[72] - ZYNLONTA is being developed in Japan through a partnership with Mitsubishi Tanabe Pharma Corporation[5] - The company entered exclusive licensing agreements with Sobi for Europe and MTPC for Japan to develop and commercialize ZYNLONTA in hematologic and solid tumor indications[61] ZYNLONTA Clinical Trial Results - In the Phase 1 trial, ZYNLONTA showed a 42.3% ORR in relapsed or refractory DLBCL patients, with 23.4% achieving complete response and 19.0% partial response[83] - ZYNLONTA's median duration of response (DoR) was not reached for complete responders and was 2.86 months for partial responders, with an overall DoR of 4.47 months[84] - In the Phase 1 trial, 77.7% of relapsed or refractory DLBCL patients experienced Grade ≥3 treatment-emergent adverse events (TEAEs), with neutrophil count decrease being the most common at 38.1%[81] - ZYNLONTA's Phase 1 trial in relapsed or refractory MCL showed a 46.7% ORR, with 33.3% achieving complete response and 13.3% partial response[85] - In the Phase 1 clinical trial for relapsed or refractory follicular lymphoma (FL), 64.3% of patients achieved a complete response (CR) and 14.3% achieved a partial response (PR), resulting in an overall response rate (ORR) of 78.6%[86] - The Phase 2 clinical trial for relapsed or refractory diffuse large B-cell lymphoma (DLBCL) showed an ORR of 48.3%, with 24.8% of patients achieving a CR and 23.4% achieving a PR[94] - The median duration of response (DoR) for patients who achieved a response in the DLBCL trial was 13.37 months, while the median DoR for patients who achieved a CR was not reached[99] - Grade ≥3 treatment-emergent adverse events (TEAEs) were reported in 73.8% of patients in the DLBCL trial, with neutropenia being the most common at 26.2%[93] - The median progression-free survival (PFS) in the DLBCL trial was 4.93 months, and the median overall survival (OS) was 9.53 months[100] - In the DLBCL trial, 18.6% of patients discontinued treatment due to treatment-related adverse events, with gamma-glutamyltransferase increase being the most common cause at 11.7%[94] - In the DLBCL trial, patients with double-hit or triple-hit disease had an ORR of 33.3%, while those with transformed disease had an ORR of 44.8%[97] - The median number of treatment cycles received in the DLBCL trial was 4.6, with a maximum of 26 cycles[93] - Patients aged ≥65 years in the DLBCL trial did not show an increase in adverse events compared to younger patients[94] - 20 patients enrolled in the safety run-in for Lonca-R showed an ORR of 75% and CR of 40% in SOHO 2022[102] ZYNLONTA Combination Therapies and Future Trials - The company is exploring ZYNLONTA in combination with bispecific antibodies like glofitamab, mosunetuzumab, and imvotamab[6][19] - The company is evaluating ZYNLONTA in combination with other therapies for earlier lines of treatment, including collaborations with Roche and IGM Biosciences[63][64] - The company is conducting a Phase 1 trial (LOTIS-7) to evaluate ZYNLONTA in combination with polatuzumab, glofitamab, and mosunetuzumab[63] - LOTIS-7 Phase 1b study is ongoing with a cohort receiving loncastuximab tesirine + Polivy, and two additional cohorts with CD20xCD3 bispecific antibodies planned for Q3 2023[103] - LOTIS-9 Phase 2 study is enrolling patients >80 years with DLBCL, with patients receiving 150 µg/kg for the first 2 cycles and 75 µg/kg for subsequent cycles[104] - LOTIS-10 Phase 1b study will evaluate loncastuximab tesirine in patients with R/R DLBCL or HGBCL, with enrollment expected to start in the second half of 2023[104] - Pediatric Trial 'Glo-BNHL' will study loncastuximab tesirine in combination with modified R-ICE chemotherapy, anticipated to start in the second half of 2023[105] ADC Development and Pipeline - ADCT-901 (KAAG1) and ADCT-601 (AXL) Phase 1 dose-escalation study results are expected in H1 2024, targeting solid tumors[7] - ADCT-212 (PSMA) is expected to enter clinical trials in H1 2024 for prostate cancer[7] - ADCT-701 (DLK1) is expected to enter clinical trials in H2 2023 for neuroendocrine malignancies[8] - The company is developing ADCT-601, ADCT-901, ADCT-701, and ADCT-212 for various solid tumors, aiming to address unmet medical needs in lung, prostate, breast, and colorectal cancers[61] - ADCT-901 (KAAG1) targets KAAG1, expressed in ovarian and triple-negative breast cancers, with ~20,000 new ovarian cancer cases and ~29,000 new triple-negative breast cancer cases in the U.S. in 2022[133] - ADCT-901 (KAAG1) demonstrated potent anti-tumor activity in ovarian cancer patient-derived xenograft models at 1 mg/kg[135] - ADCT-901 (KAAG1) Phase 1 clinical trial is currently in the dose escalation stage at a dose of 9 mg, with final validation of an IHC assay underway[140] - ADCT-901 (KAAG1) Phase 1 trial aims to enroll approximately 76 patients with advanced solid tumors, including cholangiocarcinoma, ovarian/fallopian tube cancers, prostate cancer, renal cell carcinoma, and triple negative breast cancer[139] - ADCT-601 (AXL) demonstrated potent anti-tumor activity in preclinical studies, with 40% complete response and 50% partial response in the MDA-MB-231 xenograft model (triple negative breast cancer)[145] - ADCT-601 (AXL) showed 25% complete response and 62.5% partial response in the ES0195 patient-derived xenograft model (esophageal cancer)[149] - ADCT-601 (AXL) exhibited superior anti-tumor activity compared to AXL-107-MMAE at the same dose of 0.3 mg/kg in the PAXF1657 pancreatic cancer patient-derived xenograft model[152] - ADCT-601 (AXL) uses Glycoconnect site-specific conjugation technology and features a unique Hydraspace spacer, improving therapeutic index in preclinical models[141] - AXL is overexpressed in various solid tumors, including non-small cell lung cancer (~201,000 new cases in 2022), pancreatic cancer (~62,000 new cases), renal cell carcinoma (~71,000 new cases), and ovarian cancer (~20,000 new cases)[141] - AXL expression is associated with poor clinical prognosis and resistance to anti-PD1 therapy, making it a promising target for combination therapies with immunotherapies[143] - Soluble AXL (sAXL) is a potential circulating biomarker for certain tumors, offering a potential clinical use in monitoring treatment response[143] - ADCT-901 (KAAG1) was well-tolerated in non-human primates at a dose of 0.3 mg/kg, with toxicity consistent with the PBD dimer warhead[137] - ADCT-601 at 0.3 mg/kg showed a 37.5% complete response rate and 37.5% tumor-free survival rate in the PAXF1657 patient-derived xenograft model[153] - ADCT-601 combined with gemcitabine increased survival rates and response rates in a pancreatic PDX model compared to monotherapy[158] - ADCT-601 Phase 1 clinical trial completed dose escalation, with 17 patients treated and 1 partial response observed[163] - ADCT-212 demonstrated potent anti-tumor activity in the LNCaP xenograft model at doses of 5 mg/kg and 10 mg/kg[166] - ADCT-701 showed a 37.5% complete response rate and 62.5% partial response rate at 1 mg/kg in the LI1097 hepatocellular carcinoma xenograft model[171] - ADCT-601 Phase 1b trial initiated in July 2022, with preliminary data expected in the first half of 2024[164] - ADCT-212 targets PSMA-expressing cancers, with PSMA expressed in over 80% of prostate cancer cases[165] - ADCT-701 targets DLK-1-expressing cancers, with DLK-1 expressed in neuroblastoma, hepatocellular carcinoma, and small cell lung cancer[169] - The company is exploring novel conjugation and linker technologies to enhance the therapeutic index of its ADCs[174] ADC Technology and Mechanisms - Antibody Drug Conjugates (ADCs) selectively deliver potent cytotoxins to tumor cells, minimizing toxicity to healthy cells, with three components: monoclonal antibody, cytotoxic warhead, and chemical linker[23][25][29] - ADCs using next-generation PBD warhead technology are approximately 100 times more potent than warheads in currently marketed ADCs, with manageable tolerability in preclinical studies[37][38] - PBD-based ADCs create interstrand DNA cross-links that evade DNA repair mechanisms, potentially enabling durable responses in heavily pre-treated and refractory patients[37][40] - The bystander effect of PBD-based ADCs allows warheads to diffuse into and kill neighboring tumor cells, even with heterogeneous antigen expression[40] - ADCs with PBD warheads induce immunogenic cell death, potentially enabling combination therapies with immuno-oncology treatments like checkpoint inhibitors[40] - The company has developed a proprietary exatecan drug-linker platform for tumor targets not suitable for PBD-based ADCs, with bystander activity and immunogenic cell death potential[41][42] - ADCs address a wide patient population, including those with relapsed or refractory disease, expanding treatment options for cancers with limited therapeutic alternatives[31] - The company’s ADC portfolio includes next-generation PBD-based ADCs and exatecan-based ADCs, targeting a diverse range of cancers with improved therapeutic indices[33][41] - Challenges in ADC development include achieving optimal therapeutic indices, designing stable linkers, and developing warheads for low or heterogeneous antigen expression[32] - The company’s ADCs aim to target antigens with low expression levels, potentially increasing the range of cancers treatable with ADCs[39] Market Opportunity and Commercialization - ZYNLONTA's market opportunity includes ~60% of CAR-T patients who relapse, with 27% of physicians not referring any patients for CAR-T in the last 3 years[18] - ZYNLONTA is positioned as a third-line therapy for DLBCL, addressing an unmet medical need due to limited treatment options and poor outcomes in relapsed or refractory cases[53] - ZYNLONTA's commercialization strategy includes a U.S. team covering over 90% of the DLBCL opportunity and strategic collaborations for international markets[66] - The company closed 2022 with $236 million in cash, with an additional $50 million milestone from Sobi and $75 million expected from Health Care Royalty Partners[10] - The company's cash runway is expected to extend into mid-2025, funding development programs[10] Clinical Trials and Regulatory Requirements - The company's products and candidates must undergo extensive preclinical and clinical testing, including FDA approval via a BLA, which involves significant time and financial resources[192] - Preclinical studies for product candidates must comply with GLP regulations, and an IND must be submitted to the FDA before human clinical trials can begin[194] - Clinical trials must adhere to GCPs, federal regulations, and IRB approvals, with results reported to public registries like clinicaltrials.gov[196] - Competitors may use publicly available clinical trial information to track the company's development progress[197] - Clinical trials outside the US may not require FDA authorization under an IND, but data can still be submitted to support a BLA if conducted in accordance with GCP requirements[198] - Phase 1 clinical trials involve small groups to assess safety, tolerability, and early effectiveness, with possible dose escalation (Phase 1a) or expansion (Phase 1b)[198] - Phase 2 clinical trials focus on proof of concept, dosing regimens, safety, and preliminary efficacy in disease-affected patients[199] - Phase 3 clinical trials require large patient groups across multiple sites to demonstrate effectiveness, safety, and benefit/risk relationships, often needing two successful trials for FDA approval[199] - Clinical trial phases may overlap, such as Phase 1/2 trials combining dose-escalation and dose-expansion stages[200] Intellectual Property and Competition - The company has over 400 issued patents in the U.S. and other countries, with expirations ranging from 2023 to 2043, and numerous pending applications[182] - The company exclusively licenses 36 patent families related to PBD-based warhead and ADC technology, with U.S. utility patents expiring between 2023 and 2038[182] - ZYNLONTA is co-owned with MedImmune, with six patent families expected to expire between 2033 and 2042[184] - The company faces competition from major pharmaceutical and biotechnology companies, including AbbVie, Daiichi Sankyo, and Roche, in the ADC and oncology markets[186] - ZYNLONTA competes with CAR-T, polatuzumab, and other therapies in the relapsed or refractory DLBCL setting, with potential new competitors like bispecific antibodies entering the market[187] Manufacturing and Supply Chain - The company has a 47-person in-house team overseeing chemistry, manufacturing, and control operations for its product candidates[176] - The company relies on third-party CMOs for manufacturing clinical and commercial supply of its product candidates, ensuring sufficient stock of ZYNLONTA for the foreseeable future[177] Disease Epidemiology and Patient Population - In 2022, there were an estimated 154,500 new cases of Non-Hodgkin Lymphoma (NHL) in the United States and EU5, with Diffuse Large B-Cell Lymphoma (DLBCL) accounting for 50,400 cases[48][49] - Approximately 40% of DLBCL patients require second-line therapy after first-line treatment, with only 20% showing a response and 3% achieving a complete response[51] - Camidanlumab Tesirine (Cami) completed Phase 1b with positive results for relapsed or refractory Hodgkin Lymphoma (HL), with an estimated 17,900 new HL cases in the United States and EU5 in 2020[54][55] - ADCT-602, targeting CD22, is under investigation for Acute Lymphoblastic Leukemia (ALL), which had an estimated 9,000 new cases in the United States and Europe in 2016[58][60] - The CD22 antigen is expressed on B cells and is a target for ADCs in treating hematological malignancies, with an estimated 7,000 new cases of ALL in the U.S. in 2022[120] Camidanlumab Tesirine (Cami) Development - Phase 2 clinical trial for Cami in relapsed or refractory HL enrolled 117 patients, with a median age of 37 and a median of 6 prior systemic therapies[110] - In the Phase 2 trial for Cami, 70.1% ORR was observed, with 33.3% achieving CR and 36.8% achieving PR[116] - Grade ≥3 TEAEs were reported in 67.5% of patients in the Cami Phase 2 trial, with thrombocytopenia being the most common at 9.4%[113] - 27.4% of patients in the Cami Phase 2 trial discontinued treatment due to TEAEs[116] - The FDA recommended a randomized confirmatory Phase 3 study for Cami to consider accelerated approval, leading the company to seek a partner for further development[118] ADCT-602 (CD22) Development - ADCT-602 (CD22) showed dose-dependent anti-tumor activity in the Ramos xenograft model, with 100% complete response at 1 mg/kg and 90% tumor-free survivors[121][122] - ADCT-602 (CD22) was well tolerated in non-human primates at 0.6 mg/kg, with reversible myelosuppression and lymphocyte depletion observed[127] - A Phase 1/2 clinical trial for ADCT-602 (CD22) in relapsed or refractory ALL is ongoing, with 21 patients treated as of July 2022, and 4 patients achieving MRD-negative remission[128][131][132]