ImmunoGen to Present Initial Data from FORWARD II Expansion Cohort of Mirvetuximab Soravtansine in Combination with KEYTRUDA at ESMO

WALTHAM, Mass.–(BUSINESS WIRE)–ImmunoGen,
Inc.
, (Nasdaq: IMGN), a leader in the expanding field of
antibody-drug conjugates (ADCs) for the treatment of cancer, today
announced that initial findings from the FORWARD II expansion cohort of
mirvetuximab soravtansine in combination with Merck’s anti-PD-1 therapy,
KEYTRUDA® (pembrolizumab), will be presented at the European
Society for Medical Oncology (ESMO) Congress from October 19-23, 2018 in
Munich, Germany. The poster will include initial safety and preliminary
anti-tumor activity for 46 patients with platinum-resistant ovarian
cancer (PROC), of whom 35 have medium or high folate receptor alpha
(FRα) expression.

Encouraging activity and favorable tolerability data from the FORWARD II
dose-escalation cohort assessing mirvetuximab soravtansine in
combination with KEYTRUDA in 14 heavily pre-treated patients with
platinum-resistant epithelial ovarian cancer (EOC) were presented in
March at the Society of Gynecologic Oncology (SGO) Annual Meeting. These
findings supported enrollment of additional patients in an expansion
cohort with full doses of both agents to further evaluate this
combination in PROC.

“Based on the data presented at SGO, we advanced mirvetuximab
soravtansine plus pembrolizumab into an expansion cohort focusing on
PROC patients with medium and high FRα expression,” said Anna
Berkenblit, M.D., Vice President and Chief Medical Officer of ImmunoGen.
“We look forward to presenting initial findings at ESMO, as we evaluate
several combinations that may ultimately enable us to treat more women
with ovarian cancer.”

Details of ImmunoGen’s poster presentation are as follows:

Title: “Mirvetuximab soravtansine, a folate receptor alpha
(FRα)-targeting antibody-drug conjugate (ADC), with pembrolizumab in
platinum-resistant ovarian cancer (PROC): Initial results of an
expansion cohort from FORWARD II, a Phase Ib study” (presentation number
949P)
Date: October 20, 2018
Time: 12:30 CEST
Lead
author:
Ursula Matulonis, M.D., Director and Program Leader,
Gynecologic Oncology Program, Dana-Farber Cancer Institute, Boston, MA

Mirvetuximab soravtansine is an ADC comprised of a FRα-binding humanized
antibody linked to the tubulin-disrupting maytansinoid DM4. This agent
activates monocytes and upregulates immunogenic cell death markers on
ovarian tumor cells, providing a rationale for combining with immune
checkpoint blockade. Mirvetuximab soravtansine is being evaluated in
combination with pembrolizumab in patients with PROC.

Additional information can be found at www.esmo.org.

ABOUT IMMUNOGEN
ImmunoGen is developing the next generation
of antibody-drug conjugates (ADCs) to improve outcomes for cancer
patients. By generating targeted therapies with enhanced anti-tumor
activity and favorable tolerability profiles, we aim to disrupt the
progression of cancer and offer our patients more good days. We call
this our commitment to “target a better now.” Our lead product
candidate, mirvetuximab soravtansine, is in a Phase 3 study for folate
receptor alpha (FRα)-positive platinum resistant ovarian cancer, and in
Phase 1b/2 testing in combination regimens. Our novel IGN candidates for
hematologic malignancies, IMGN779 and IMGN632, are in Phase 1 studies.

Learn more about who we are, what we do, and how we do it at www.immunogen.com.

KEYTRUDA® is a registered trademark of Merck Sharp & Dohme Corp., a
subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA.

This press release includes forward-looking statements based on
management’s current expectations. These statements include, but are not
limited to, ImmunoGen’s ability to expand the addressable patient
population for mirvetuximab soravtansine and the regulatory and
commercial potential of mirvetuximab combinations in earlier lines of
therapy. For these statements, ImmunoGen claims the protection of the
safe harbor for forward-looking statements provided by the Private
Securities Litigation Reform Act of 1995. Various factors could cause
ImmunoGen’s actual results to differ materially from those discussed or
implied in the forward-looking statements, and you are cautioned not to
place undue reliance on these forward-looking statements, which are
current only as of the date of this release. It should be noted that
there are risks and uncertainties related to the development of novel
anticancer products, including risks related to preclinical and clinical
studies, their timings and results, and the potential that earlier
clinical studies may not be predictive of future results. A review of
these risks can be found in ImmunoGen’s Annual Report on Form 10-K for
the year ended December 31, 2017 and other reports filed with the
Securities and Exchange Commission.

Contacts

INVESTOR RELATIONS CONTACT
ImmunoGen, Inc.
Sarah Kiely,
781-895-0600
sarah.kiely@immunogen.com
or
MEDIA
CONTACT

ImmunoGen, Inc.
Courtney O’Konek, 781-895-0600
courtney.okonek@immunogen.com
or
FTI
Consulting
Robert Stanislaro, 212-850-5657
robert.stanislaro@fticonsulting.com

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