O2h to Provide Discovery Support to Karyopharm Therapeutics, Inc.

CAMBRIDGE, England, June 7, 2010 - O2h (Ahmedabad, India) is pleased to announce the signing of an
agreement with Karyopharm Therapeutics, Inc. (Newton, Massachusetts, USA)
under which O2h will provide Karyopharm discovery services to advance
Karyopharm's lead small molecule program toward the nomination of a
development candidate.

Dr. Sharon Shacham, co-founder and CSO of Karyopharm, said, "O2h has an
excellent reputation as an efficient and high quality discovery services
provider. We look forward to working with the O2h team to further the
progress of our first program as we continue to build our proprietary
expertise developing drugs targeting the nuclear pore complex machinery."

Sunil Shah, CEO of O2h, said, "It has been a pleasure working with Dr.
Shacham as she is one of the most dynamic and focused drug discovery leaders
that I have met. Leveraging Dr. Shacham's proprietary and proven approach to
drug discovery, I'm optimistic that Karyopharm will be a great success."

About Oxygen Healthcare Ltd

O2h is a 5-year-old discovery services company co-located in Cambridge,
UK and Ahmedabad, India. The Indian operations provide a high level of
chemistry expertise while the UK office provides project management support.
Current clients of O2h include several top 20 pharmaceutical and
biotechnology companies in the US, Europe and Japan. O2h adheres to the
highest standards of performance with a particular emphasis on rapid
interactive communications and delivery speed. Services provided by O2h
include FTE-based synthetic chemistry, medicinal chemistry, computational
chemistry, full services lab-units and ADME. Further information on O2h can
be found at www.o2h.com.

    Contact information:
    Dr. Ekta Ahuja
    info@o2h.com
    OXYGEN HEALTHCARE LTD
    23 Cambridge Science Park
    CB4 0EY

About Karyopharm Therapeutics, Inc.

Karyopharm is the first company to focus on discovering and developing
therapies by targeting the nuclear pore complex machinery. The company is
rapidly advancing small molecules that modulate the activity of critical
pathways in cancer, viral and inflammatory diseases. IND enabling studies of
its first program targeting CRM1 will begin this year. For more information
please visit www.karyopharm.com.

    Contact Information:
    Sharon Shacham, PhD
    Co-founder and Chief Scientific Officer
    Karyopharm Therapeutics, Inc.
    info@karyopharm.com

Contact information: Dr. Ekta Ahuja, info at o2h.com, OXYGEN HEALTHCARE LTD, +44(0)1223-437014; Contact Information: Sharon Shacham, PhD, Co-founder and Chief Scientific Officer, Karyopharm Therapeutics, Inc., info at karyopharm.com