Home News One year data from Kiadis…

Amsterdam, The Netherlands, November 3, 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 data from the Company’s ongoing Phase II
clinical trial (NCT01794299/EudraCT 2012-004461-41) with its lead product ATIR101™ has
been selected by the American Society of Hematology (ASH) Program Committee for an oral
presentation at the 58th Annual Meeting in San Diego, California on December 5, 2016.

The abstract will be presented by Dr. Denis-Claude Roy, Professor of Medicine at the
University of Montreal and one of the principal investigators for the trial, and will provide
one year data from Kiadis Pharma’s international multi-center study, in which a total of 23
leukemia patients, including patients with acute myeloid leukemia (AML), acute
lymphoblastic leukemia (ALL) and myelodysplastic syndrome (MDS), have been enrolled to
be treated with ATIR101™ as part of their transplant regimen. In addition, the abstract
includes a comparison to a historic control group.

Abstract title: Donor Lymphocytes Depleted of Alloreactive T-Cells (ATIR101) Improve Event-Free Survival (GRFS) and Overall Survival in a T-Cell Depleted Haploidentical HSCT: Phase 2 Trial in Patients with AML and ALL
Date: Monday, December 5, 2016 from 6:15 to 7:45 PM Eastern Daylight Time (EDT) (presentation time: 6:30 PM EDT)
Publication: 1226
Session: 711. Cell Collection and Processing: Immunotherapy, Immunomodulation and Immune Reconstitution
Location: San Diego Convention Center, Room 30

The full abstract is available to view online at www.hematology.org later today at 9:00 AM
EDT. In addition, the abstract will be published online in the December 1, 2016 supplemental
volume of Blood.

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 focused on cell-based immunotherapy products for the treatment of blood
cancers and inherited blood disorders. The Company’s products have the potential to address
the risks and limitations connected with allogeneic hematopoietic stem cell transplantation
(HSCT), namely Graft-versus-Host-Disease (GVHD), cancer relapse, opportunistic infections
and limited matched donor availability. The Company believes that HSCT could become a firstchoice
treatment for blood cancers, inherited blood disorders and possibly autoimmune
diseases and solid organ transplantations.

In April 2016, the Company reported positive Phase II results with its lead product ATIR101™
in patients with blood cancer. The data showed that ATIR101™ significantly reduced
Transplant Related Mortality and significantly improved Overall Survival. In addition,
ATIR101™ did not elicit grade III-IV GVHD in any patient. A Phase III clinical trial with
ATIR101™ is expected to be initiated in the second half of 2016. ATIR101™ has been granted
Orphan Drug Designations both in the US and Europe. The Company’s second product
candidate, ATIR201™, addresses inherited blood disorders with an initial focus on
thalassemia, a disease which results in destruction of red blood cells in patients. ATIR201™ is
expected to enter Phase I/II clinical development in the second half of 2016.

Kiadis Pharma, based in Amsterdam, The Netherlands, was granted an Advanced Therapy
Medicinal Product (ATMP) certificate for manufacturing quality and non-clinical data by the
European Medicines Agency (EMA). The Company’s shares are listed on Euronext Amsterdam
and Euronext Brussels.

Company 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.