To the shareholders of ADC Therapeutics SA Invitation to the Annual General Meeting Date and Time : Thursday

To the shareholders of ADC Therapeutics

Invitation to the Annual General Meeting

Date and Time: Thursday, June 10, 2021, at 8:00 a.m.

CEST / 2:00 p.m. EDT

Location: Headquarters of ADC Therapeutics SA, Biop le,

Route de la Corniche 3B, 1066 Epalinges, Switzerland (no physical shareholder attendance)

2020 was a transformational year for ADC Therapeutics

as we made remarkable progress across many aspects of the business and positioned ourselves for commercial success. Highlights include

the first regulatory submission for our lead clinical program loncastuximab tesirine (Lonca), the successful completion of our initial

public offering and the strategic growth of the company worldwide. I am very proud of our achievements, especially considering the challenges

presented by the COVID-19 pandemic. I would like to thank our committed employees and the dedicated physicians and patients involved in

our clinical trials for their tremendous efforts and contributions.

If it is approved by the FDA, we will be ready

to launch our first product - Lonca. We brought on an accomplished senior commercial leader who immediately set her sights on the most

talented and experienced commercial representatives in hematology/oncology. Chief Commercial Officer Jennifer Herron has assembled a very

strong team of experienced hematology therapeutic specialists who are well connected to key hematologist/oncologists and their colleagues.

In this COVID-19 environment, our teams are trained and prepared to optimize customer engagement with a hybrid approach and strong digital

support depending on local guidelines as well as customer preference.

Lonca, a CD-19 targeted antibody drug conjugate

(ADC) for the treatment of patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL), has a differentiated product profile

that will make it an attractive choice for physicians and patients. In our pivotal Phase 2 trial, Lonca demonstrated significant single-agent

activity, a manageable safety profile, and consistent overall response rates across the broad patient population, highlighting its potential

to fill a significant unmet need in the DLBCL market. The results of this pivotal trial were the basis of the Biologics License Application

(BLA) submission to the U.S. Food and Drug Administration (FDA) in September 2020. This BLA submission has been granted priority review

with a PDUFA target date of May 21, 2021.

Beyond third-line DLBCL, we believe Lonca has

the potential to expand into additional indications and earlier lines of therapy. In July 2020, we initiated the pivotal Phase 2 portion

of the LOTIS 3 trial of Lonca in combination with ibrutinib for the treatment of patients with relapsed or refractory DLBCL or Mantle

Cell Lymphoma (MCL). We also continue to enroll patients in a confirmatory Phase 3 trial of Lonca in combination with rituximab in second-line

transplant-ineligible patients with DLBCL. Additionally, we plan to initiate a dose escalation study for Lonca

in front-line patients in combination with R-CHOP.

Finally, we are initiating a pivotal Phase 2 trial in relapsed or refractory follicular lymphoma in the first half of 2021.

Our second lead program is camidanlumab tesirine

(Cami), a PBD-based ADC targeting CD25. We continue to advance this program in both Hodgkin lymphoma (HL) and in solid tumor indications.

We presented the interim results of the phase 2 pivotal trial in HL at the American Society of Hematology annual meeting, which demonstrated

significant single-agent clinical activity in a heavily-pretreated patient population. The pivotal phase 2 trial in relapsed or refractory

HL is fully enrolled, and we expect to have additional interim data in the first half of this year. Based on encouraging preclinical data,

we also believe Cami may have potential benefit in solid tumors. To that end, we are exploring Cami in a Phase 1b trial in solid tumors

in combination with pembrolizumab. Beyond Lonca and Cami, we have a broad portfolio, with two early clinical programs in hematology and

solid tumors, an Investigational New Drug (IND) application is planned this year for a novel ADC targeting KAAG1 in solid tumors and an

early research pipeline of six additional programs in pre-clinical development.

2020 was also a significant year in terms of the

evolution of the company. In May 2020, we successfully completed our initial public offering and secured a convertible credit facility,

with a follow-on public offering completed in September. The capital raised gives us a strong balance sheet and will allow us to fund

the development of our promising clinical programs. As for other business initiatives, to expand our global reach, we formed Overland

ADCT BioPharma to develop and commercialize Lonca and three other pipeline assets in Greater China and Singapore.

As ADC Therapeutics expands its commercial prospects,

we have made key appointments to the company's management team and Board of Directors to maximize our potential. Ron Squarer joined

us as Chairman of the Board of Directors and an advisor to the company, Victor Sandor joined the Board of Directors and two veteran pharmaceutical

executives joined our leadership team - Jennifer Creel as Chief Financial Officer and Joseph Camardo as Head of Medical Affairs.

Looking to 2021, our key objectives are clear.

We are prepared to launch Lonca, if approved, thanks to the dedication of our clinical, regulatory and manufacturing teams. At the same

time, we are focused on advancing our other clinical programs for Lonca to expand its use, and also Cami and our other pipeline assets

using our proprietary highly targeted ADC technology.

In the attached, you find the Invitation to our

2021 Annual General Meeting, our first general meeting of shareholders as a public company. The continuing exceptional circumstances of

the COVID-19 pandemic do not allow us to hold our 2021 Annual General Meeting with shareholders attending in person. The Board of Directors

very much regrets that this important event cannot be held in person. We thank you for your understanding and look forward to your personal

participation when circumstances permit in the future.

We sincerely thank you for your continued support

as we execute on our mission of delivering unique targeted cancer therapies to transform the lives of patients and their families.

Chris Martin, Chief Executive Officer

Important notice regarding COVID-19

Unfortunately, the continuing exceptional

circumstances of the COVID-19 pandemic do not allow us to hold our 2021 Annual General Meeting with shareholders attending in person.

On September 11, 2020, the Swiss Federal

Council extended COVID-19 Ordinance 3 until December 31, 2021. In accordance with these regulations, shareholders will not be permitted

to be physically present, and may exercise their rights at our 2021 Annual General Meeting exclusively by sending voting instructions

to the Independent Proxy. See the "Organizational Information" section at the end of this document for more detail.

We take the safety of our shareholders,

directors, officers, employees and service providers very seriously, and hope you understand the need for these measures.

Agenda and Proposals of the Board of Directors

The Board of Directors

proposes that the Management Report, the Annual Financial Statements and the Consolidated Financial Statements for the fiscal year 2020

be approved, and that the Auditors' Reports be acknowledged.

The Board of Directors

proposes that the members of the Board of Directors and the Executive Committee be discharged from liability for the fiscal year 2020.

The Board of Directors

proposes that the loss of the Company be carried forward as follows:

The Board of Directors proposes to increase

and renew the Company's Authorized Share Capital by CHF 1,170,800, by amending Article 4a, Paragraph 1 of the Articles

of Association as follows (the proposed amendments are underlined):

"The Board of Directors shall

be authorized to increase the share capital at any time, including in connection with an intended takeover, until June 9, 2023,

by a maximum amount of CHF 3,130,800 by issuing a maximum of 39,135,000 fully paid in registered shares with a par

value of CHF 0.08 each. Increases in partial amounts shall be permissible."

The Board of Directors has nominated

Viviane Monges as new member of the Board of Directors (see agenda item 6.12). To enable her election, the maximum number of directors

set forth in the current Articles of Association must be increased from eleven to twelve.

The Board of Directors proposes that

Article 15 of the Articles of Association be amended to increase the maximum size of the Board of Directors as follows (the proposed amendment

"The Board of Directors shall

consist of not fewer than 3 and not more than 12 members."

The term of office for the Chairman and

all members of the Board of Directors expires at the end of the 2021 Annual General Meeting. The Board of Directors proposes re-election

of the current members of the Board of Directors, including the Chairman, for a term of office until completion of the 2022 Annual General

The Board of Directors further proposes

to elect Viviane Monges as a new member of the Board of Directors.

Information on the professional background