Home News Kiadis Pharma and The Leukemia…

~ LLS will fund the Phase II development via an equity investment in Kiadis Pharma ~

Amsterdam, The Netherlands, February 1, 2016 – Kiadis Pharma N.V. (“Kiadis Pharma” or
the “Company”) (Euronext Amsterdam and Brussels: KDS), a clinical stage biopharmaceutical
company developing innovative T-cell immunotherapy treatments for blood cancers and
inherited blood disorders, today announces that it has entered into a partnership with The
Leukemia & Lymphoma Society (LLS) under which LLS will fund the Phase II development of
Kiadis Pharma’s lead product, ATIR101™, through an equity investment of approximately $1 million.

LLS is investing via its Therapy Acceleration Program (TAP), a strategic initiative to partner
directly with biotechnology companies to help accelerate the development of
promising therapies, and the funds will be used to finance Kiadis Pharma’s second ongoing
Phase II trial in leukemia patients. The Company intends to continue this trial into a
randomized controlled Phase III pivotal study that is planned to start later this year. This
ongoing Phase II trial is investigating the repeated dosing of ATIR101™ as an adjunctive
treatment to a T-cell depleted haploidentical hematopoietic stem cell transplantation (HSCT)
(donor cells from a half-matched related donor) in adult patients with acute myeloid leukemia
(AML) or acute lymphoblastic leukemia (ALL). The trial (CR-AIR-008; NCT02500550 / EudraCT
2015-002821-20) is conducted under an IND of the United States Food and Drug
Administration and is set up to enroll patients in the United States as well as other countries,
including Canada, Belgium and the United Kingdom.

Manfred Rüdiger, PhD, Chief Executive Officer of Kiadis Pharma, commented: “We are
pleased to be partnering with the world’s largest voluntary health agency focused on blood
cancers. We see this as another validation of our innovative product candidate ATIR101™. The
extensive network and expertise of The Leukemia & Lymphoma Society will be extremely
valuable to us as we prepare to set up the pivotal Phase III study later this year. The fact that
LLS is investing into Kiadis Pharma with equity is also a strong sign of confidence in what we do
and our goal remains to be to bring this important product to patients as quickly as possible.”

Louis J. DeGennaro, Ph.D., LLS’s President and CEO, added: Stem cell transplantation is one of
the most effective curative treatments for blood cancer patients, but it comes with great risk
of life-threatening infection and graft versus host disease (GVHD). Kiadis Pharma’s ATIR101™
shows promise in fighting these infections by boosting the patient’s immune system whilst also
reducing GVHD. LLS is enthusiastic about supporting this program which we hope will improve
outcomes for patients with blood cancers.”

About ATIR101™
For patients suffering from blood cancers, an allogeneic hematopoietic stem cell
transplantation (HSCT) is generally regarded as the most effective curative approach. During
an HSCT treatment, the bone marrow, harboring the diseased cancer cells, is completely
destroyed and subsequently replaced by stem cells in the graft from a healthy donor. After
an HSCT treatment it usually takes the patient at least six to twelve months to recover to
near-normal blood cell levels and immune cell functions. During this period, the patient is
highly vulnerable to infections caused by bacteria, viruses and fungi but also to disease

ATIR101™ (Allodepleted T-cell ImmunotheRapeutics) provides for a safe donor lymphocyte
infusion (DLI) from a partially matched (haploidentical) family member without the risk of
causing severe Graft-versus-Host-Disease (GVHD). The T-cells in ATIR101™ will help fight
infections and remaining tumor cells and thereby bridge the time until the immune system
has fully re-grown from stem cells in the transplanted graft.

In ATIR101™, T-cells that would cause GVHD are eliminated from the donor lymphocytes
using Kiadis Pharma’s photodepletion technology, minimizing the risk of GVHD and
eliminating the need for prophylactic immune-suppression. At the same time, ATIR101™
contains potential cancer killing T-cells from the donor that could eliminate residual cancer
cells and help prevent relapse of the disease, known as the Graft-versus-Leukemia (GVL)

Therefore, ATIR101™, administered as an adjunctive immuno-therapeutic on top of HSCT,
provides the patient with functional, mature immune cells from a partially matched family
donor that can fight infections and tumor cells but that do not cause GVHD. ATIR101™ thus
has the potential to make curative HSCT a viable option to many more patients.

The Company estimates that approximately 35% of patients who are eligible and in urgent
need of HSCT will not find a matching donor in time. A partially matched (haploidentical)
family donor, however, will be available to over 95% of patients.

ATIR101™, consisting of donor T-cells that fight infections and residual tumor cells while not
eliciting severe GVHD, is designed to result in low relapse rates and low rates of death due to
infections, in the absence of severe acute GVHD.

About Kiadis Pharma
Kiadis Pharma is a clinical stage biopharmaceutical company focused on research,
development and future commercialization of cell-based immunotherapy products for the
treatment of blood cancers and inherited blood disorders. The Company believes that its
innovative products have the potential to address the current risks and limitations connected
with allogeneic hematopoietic stem cell transplantation (HSCT), being graft-versus-hostdisease
(GVHD), cancer relapse, opportunistic infections and limited matched donor
availability. HSCT is generally regarded as the most effective curative approach to blood
cancers and certain inherited blood disorders and the Company expects that HSCT could
become a first-choice treatment for blood cancers and inherited blood disorders once current
risks and limitations are addressed, thereby meeting a significant unmet medical need with its

Currently, the Company’s product ATIR101™ is being tested using a single dose regimen in an
open-label Phase II trial in patients with blood cancer who have not found a matching donor
and where a partially matched (haploidentical) family member is used as donor for HSCT.
Kiadis Pharma announced full enrolment of this trial in July 2015. The primary endpoint for
the last patient in this trial will be reached at the end of Q1, 2016, top-line results to follow at
the beginning of Q2, 2016. Very encouraging and positive interim data of this trial was
presented recently at ASH2015.

In addition, the Company is enrolling blood cancer patients in a further Phase II clinical trial to
study the safety and efficacy of administrating a second dose of ATIR101™ to further improve
the HSCT outcome.

The European Medicines Agency (EMA) has issued an Advanced Therapy Medicinal Product
(ATMP) certificate for manufacturing quality and non-clinical data to the Company, and to
date Kiadis Pharma is one of only five companies that have received such a certificate

ATIR101™ has been granted Orphan Drug Designations both in the US and Europe.

ATIR201™ will be developed for inherited blood disorders with an initial focus on thalassemia,
an inherited blood disorder which results in improper oxygen transport and destruction of red
blood cells in a patient. ATIR201™ is expected to enter clinical development for thalassemia
with a Phase I/II trial in the first quarter of 2016.

Kiadis Pharma is based in Amsterdam, the Netherlands and its shares are listed on Euronext
Amsterdam and Euronext Brussels.

About The Leukemia & Lymphoma Society
The Leukemia & Lymphoma Society® (LLS) is the world’s largest voluntary health agency
dedicated to blood cancer. The LLS mission: Cure leukemia, lymphoma, multiple myeloma,
and improve the quality of life of patients and their families. LLS funds lifesaving blood cancer
research around the world, provides free information and support services, and is the voice
for all blood cancer patients seeking access to quality, affordable, coordinated care.

Founded in 1949 and headquartered in White Plains, NY, United States of America, LLS has
chapters throughout the United States and Canada. To learn more, visit www.LLS.org. Patients
should contact the Information Resource Center at (800) 955-4572, Monday through Friday, 9
a.m. to 9 p.m. ET.

For more information, please contact:
Manfred Rüdiger, CEO
Kiadis Pharma
Entrada 231-234
1114 AA Amsterdam-Duivendrecht
The Netherlands
Tel. +31 20 314 02 50

International Media and Investor Contact:
Mary-Jane Elliott, Lindsey Neville, Hendrik Thys
Consilium Strategic Communications
Tel: +44 (0) 203 709 5708

Forward Looking Statements
Certain statements, beliefs and opinions in this press release are forward-looking, which
reflect Kiadis Pharma’s or, as appropriate, Kiadis Pharma’s directors’ current expectations
and projections about future events. By their nature, forward-looking statements involve a
number of risks, uncertainties and assumptions that could cause actual results or events to
differ materially from those expressed or implied by the forward-looking statements. These
risks, uncertainties and assumptions could adversely affect the outcome and financial effects
of the plans and events described herein. A multitude of factors including, but not limited to,
changes in demand, competition and technology, can cause actual events, performance or
results to differ significantly from any anticipated development. Forward looking statements
contained in this press release regarding past trends or activities should not be taken as a
representation that such trends or activities will continue in the future. As a result, Kiadis
Pharma expressly disclaims any obligation or undertaking to release any update or revisions
to any forward-looking statements in this press release as a result of any change in
expectations or any change in events, conditions, assumptions or circumstances on which
these forward-looking statements are based. Neither Kiadis Pharma nor its advisers or
representatives nor any of its subsidiary undertakings or any such person’s officers or
employees guarantees that the assumptions underlying such forward-looking statements are
free from errors nor does either accept any responsibility for the future accuracy of the
forward-looking statements contained in this press release or the actual occurrence of the
forecasted developments. You should not place undue reliance on forward-looking
statements, which speak only as of the date of this press release.