Kite Announces End of Phase 1 ZUMA-3 Results for KTE-X19 in Adult Patients with Relapsed or Refractory Acute Lymphoblastic Leukemia

— Data Show High Rates of Response to Single Infusion of KTE-X19
—

— Phase 2 Portion of ZUMA-3 is Ongoing and Includes Dosing and
Revised Safety Management Protocol Studied in Phase 1 —

CHICAGO–(BUSINESS WIRE)–Kite, a Gilead Company (Nasdaq: GILD), today announced results from the
completed Phase 1 of the ZUMA-3 study evaluating KTE-X19, an
investigational CD19 chimeric antigen receptor T (CAR T) cell therapy.
ZUMA-3 is a single-arm Phase 1/2 study in adult patients with relapsed
or refractory acute lymphoblastic leukemia (ALL). The results provide
guidance on dosing and safety management for KTE-X19 to inform the
ongoing Phase 2 study. The data were presented during an oral session at
the 2019 American Society of Clinical Oncology (ASCO) Annual Meeting in
Chicago, May 31 – June 4 (Abstract #7006).

By the end of Phase 1, 45 patients received KTE-X19 at one of three
different doses levels [2 x 10⁶ cells/kg (n=6), 1 x 10⁶
cells/kg (n=23), or 0.5 x 10⁶ cells/kg (n=16)]. Patients
enrolled in this study were primary refractory or relapsed/refractory
after at least two prior lines of therapy. Of 41 patients who were
evaluable for efficacy after a minimum two months of follow-up (median
follow-up of 16 months), 68 percent achieved complete response (CR) or
CR with incomplete hematological recovery (CRi) and 100 percent of
responders had undetectable minimal residual disease (MRD). Of the 23
patients treated with the dose level that will be used in the ongoing
Phase 2 study (1 x 10⁶ cells/kg), 19 were evaluable for
efficacy. At the time of data cut-off (median duration of remission =
12.9 months), 16 (84 percent) patients achieved CR or CRi, and 12
patients (75 percent) were in ongoing response.

No dose-limiting toxicities (DLTs) were identified. Grade ≥3 cytokine
release syndrome (CRS) events and neurologic events occurred in 29
percent and 38 percent of all patients, respectively. As previously
reported, two patients experienced KTE-X19–related Grade 5 adverse
events (AEs) during the study; one developed stroke in the context of
CRS and neurologic events, and one experienced multiorgan failure
secondary to CRS. Among patients receiving 1 x 10⁶ cell/kg
(n=23), 26 percent experienced Grade ≥3 CRS, and 43 percent experienced
Grade ≥3 neurologic events.

A revised AE management protocol was implemented in nine patients
treated with 1 x10⁶ cells/kg of KTE-X19 during the study. In
this revised protocol, corticosteroids were initiated at onset of Grade
≥2 neurologic events (versus previous onset of Grade 3) and tocilizumab
was only given for management of toxicities in the context of CRS
(versus prophylactic administration in Cohort 2). Of those patients, two
(22 percent) had Grade 3 CRS and one (11 percent) had Grade 3 neurologic
events. There were no Grade 4/5 events.

“Adults with relapsed or refractory ALL represent an extremely
difficult-to-treat patient population,” said Bijal Shah, MD, ZUMA-3
investigator and medical oncologist, Moffitt Cancer Center, Tampa,
Florida. “We’re encouraged by the high response rates in this study, as
well as the reduced incidence and severity of CRS and neurologic events
that were observed following implementation of the revised safety
management protocol. We are now evaluating the use of KTE-X19 at the
selected dose with this safety management protocol in the ongoing ZUMA-3
Phase 2 study.”

“The completion of the Phase 1 portion of the ZUMA-3 trial is an
important milestone for our second investigational CAR T cell therapy,”
said John McHutchison, AO, MD, Chief Scientific Officer, Head of
Research and Development, Gilead. “We are pleased with the high response
rates observed with KTE-X19 in this trial, and the progress of our
broader effort aimed to further improve the benefit/risk profile of CAR
T therapy through the investigation of novel safety management
approaches.”

This abstract has also been selected to be included in the 2019 Best of
ASCO^® program, which will be held this summer following the
ASCO Annual Meeting.

KTE-X19 is an investigational therapy that has not been approved by the
U.S. Food and Drug Administration (FDA) or any regulatory authority for
any uses. Efficacy and safety have not been established.

About ALL

ALL is an aggressive type of blood cancer which can also involve the
lymph nodes, spleen, liver, central nervous system and other organs.

About ZUMA-3

ZUMA-3 is an ongoing multicenter, registrational Phase 1/2 study in
adult patients (≥18 years old) with ALL whose disease is refractory to
or has relapsed following standard chemotherapy or hematopoietic stem
cell transplantation. The objectives of the study are to evaluate the
safety and efficacy of KTE-X19 in this patient population.

About KTE-X19

KTE-X19 is an investigational CD19 CAR T cell therapy. KTE-X19 has the
same construct as axicabtagene ciloleucel; however, the manufacturing
process for KTE-X19 differs from that of axicabtagene ciloleucel and
includes the enrichment of lymphocytes. Lymphocyte enrichment is
necessary in certain B-cell malignancies for which KTE-X19 in under
investigation. KTE-X19 is currently in Phase 1/2 trials in acute
lymphoblastic leukemia (ALL), mantle cell lymphoma (MCL) and chronic
lymphocytic leukemia (CLL).

About Kite

Kite, a Gilead Company, is a biopharmaceutical company based in Santa
Monica, California. Kite is engaged in the development of innovative
cancer immunotherapies. The company is focused on chimeric antigen
receptor and T cell receptor engineered cell therapies. For more
information on Kite, please visit www.kitepharma.com.

About Gilead Sciences

Gilead Sciences, Inc. is a research-based biopharmaceutical company that
discovers, develops and commercializes innovative medicines in areas of
unmet medical need. The company strives to transform and simplify care
for people with life-threatening illnesses around the world. Gilead has
operations in more than 35 countries worldwide, with headquarters
in Foster City, California. For more information on Gilead Sciences,
please visit the company’s website at www.gilead.com.

Forward-Looking Statement

This press release includes forward-looking statements, within the
meaning of the Private Securities Litigation Reform Act of 1995 that are
subject to risks, uncertainties and other factors, including Kite’s
ability to complete Phase 2 of the ZUMA-3 study of KTE-X19 in adult
patients with relapsed or refractory acute lymphoblastic leukemia in the
currently anticipated timelines, or at all. In addition, there is the
possibility of unfavorable results from other ongoing and additional
clinical trials involving KTE-X19. Further, Kite may be unable to obtain
regulatory approval for KTE-X19 from the FDA or other regulatory
authorities. All statements other than statements of historical fact are
statements that could be deemed forward-looking statements. These risks,
uncertainties and other factors could cause actual results to differ
materially from those referred to in the forward-looking statements. The
reader is cautioned not to rely on these forward-looking statements.
These and other risks are described in detail in Gilead’s Quarterly
Report on Form 10-Q for the quarter ended March 31, 2019, as filed with
the U.S. Securities and Exchange Commission. All forward-looking
statements are based on information currently available to Gilead and
Kite, and Gilead and Kite assume no obligation to update any such
forward-looking statements.

For more information on Kite, please visit the company’s website at www.kitepharma.com.
Learn more about Gilead at www.gilead.com,
follow Gilead on Twitter (@GileadSciences) or call Gilead Public Affairs
at 1-800-GILEAD-5 or 1-650-574-300

Contacts

Sung Lee, Investors
(650) 524-7792

Nathan Kaiser, Media
(650)
522-1853