Inc. (Nasdaq: IMGN), a biopharmaceutical company that develops
targeted anticancer therapeutics, today reported encouraging clinical
data with its IMGN901 product candidate in the treatment of relapsed and
relapsed/refractory multiple myeloma (MM), including prolonged benefit
in patients whose disease had progressed on multiple prior treatment
regimens. These findings were reported at the American Society of
Hematology (ASH) 51th Annual Meeting and Exposition being
held in New Orleans, MA.
IMGN901 is an investigational agent designed to kill cancer cells that
express CD56, a protein. It consists of a CD56-binding antibody with a
potent cancer-cell killing agent, DM1, attached to it using an
engineered linker. IMGN901 is in Phase I testing for the treatment of
CD56-expressing solid tumors and multiple myeloma. It is wholly-owned by
In the trial reported today, new cohorts of patients received
increasingly greater amounts of IMGN901 – used as a single agent – until
the maximum tolerated dose was established. All of the patients had
CD56-expressing MM that had progressed on multiple therapies, and most
had previously been treated with at least six chemotherapy regimens.
“What was particularly impressive was the duration of benefit seen with
IMGN901 in a number of these heavily pre-treated patients,” commented
Asher Chanan-Khan, MD, of the Roswell Park Cancer Institute. “IMGN901
demonstrated encouraging activity as a single agent in a disease often
treated with combination therapy, and the tolerability findings to date
support evaluating it used together with other active agents.”
Among the twenty-six patients treated with IMGN901 at any dose level:
One patient had a partial response (PR) while receiving IMGN901. This
patient has continued on treatment for more than a year.
Three patients had a minimal response (MR) while receiving IMGN901,
and two of these patients remained on treatment for at least 45 weeks.
The third patient withdrew from the study due to a broken leg while
continuing to show disease improvement.
Eleven patients had stable disease (SD), with eight of these patients
remaining on treatment for at least 12 weeks at the time of data
cut-off for presentation. These include four patients who have
received IMGN901 for at least 24 weeks and two other patients still
The overall clinical benefit rate (objective responses plus sustained
stable disease) was 46%.
Ten patients remained on IMGN901 longer than on regimens received
earlier in the course of their disease, and eight of these patients were
on IMGN901 longer than on their last regimen with approved therapies.
Typically in the treatment of cancer, patients have their best treatment
responses early in the course of their disease and respond less well to
IMGN901 was found to be generally well tolerated and was not associated
with significant myelosuppression or other side effects that would limit
its ability to be administered in combination with other active agents.
The most common side effects were mild-to-moderate headache, fatigue and
neuropathy. Grade 3 fatigue was reported in two patients and was the
only grade 3 side effect reported in more than one patient; no more
severe (grade 4 or 5) side effects were associated with use of the
agent. The maximum tolerated dose was established to be 112 mg/m2/week.
“This trial – Study 003 – has provided us with important information on
the safety of IMGN901 when used alone to treat multiple myeloma that has
progressed on numerous prior therapies,” noted James O’Leary, MD, Vice
President and Chief Medical Officer of ImmunoGen. “The expansion phase
of this trial, which is now underway, provides for patients with less
heavily pretreated multiple myeloma to receive IMGN901 at the maximum
tolerated dose, enabling us to better assess its activity when used as a
Dr. O’Leary continued, “Multiple myeloma is often treated with a
combination of therapies with different mechanisms of action. Thus, we
feel it’s important to also assess IMGN901 as part of a multi-agent
regimen. The profile of IMGN901 suggests that it’s particularly well
suited to use in combination, as it works by a novel mechanism and has
not been associated with side effects that would limit its ability to be
used with other agents. We expect patient dosing in our Study 005
combination trial to begin shortly.”