London, UK, Cambridge, MA, and New Orleans, LA: 7 December 2009
-Antisoma plc (LSE: ASM; USOTC: ATSMY) announces that positive final
data from a phase II trial of AS1413 in patients with secondary acute
myeloid leukaemia (secondary AML) were presented this weekend at the
American Society of Hematology (ASH) meeting in New Orleans.
Follow-up of patients has now been completed, and full results are
available:
* Eighty-eight patients with secondary AML received the novel DNA
intercalator AS1413 together with cytarabine as first-line
(remission-induction) therapy
* The remission rate was 42%, with 39% of patients achieving a
complete remission and 3% a complete remission with incomplete
bone marrow recovery
* The median duration of remission was 9.4 months, and 30% of those
who achieved remission were still alive 2 years after treatment
* Clinical benefit was maintained in older patients, with patients
over 60 achieving remission rates and remission durations similar
to those of patients under 60
* Median survival for all patients was 6.6 months
* The safety profile of the regimen was manageable and acceptable,
and consistent with that expected for AML remission-induction
therapy
Dr Harry P. Erba, Associate Professor of Internal Medicine at the
University of Michigan Health System, Principal Investigator in the
trial, and presenter of the data at ASH, said: "The phase II study of
AS1413 in secondary AML has produced encouraging data, with a 42%
remission rate and a significant fraction of durable responses in
this very poor-risk population. Based on these promising findings, a
large, randomised phase III trial is evaluating AS1413 in patients
with secondary AML."
Secondary AML is a well-characterised subset of AML that evolves from
a prior myelodysplastic syndrome or develops following radiotherapy
or chemotherapy treatment for other cancers. This contrasts with de
novo AML, where there is no obvious history leading to the disease. A
diagnosis of secondary AML carries a worse prognosis than de novo
AML. Moreover, secondary AML is often associated with other adverse
risk factors. Dr Erba added: "Patients with secondary AML have a very
poor prognosis. In the AS1413 phase II study, most patients were over
60 and almost half had leukaemic cell karyotypes associated with
unfavourable outcome."
One adverse risk factor that is common in secondary AML is multi-drug
resistance (MDR). This can occur when leukaemic cells produce
molecular pumps that expel chemotherapy drugs. MDR affects many
drugs, including the anthracyclines daunorubicin and idarubicin,
which are commonly used alongside cytarabine as standard
remission-induction treatment for AML. AS1413, by contrast, is
unaffected by MDR, since it evades the major MDR mechanisms,
including Pgp, MRP-1 and BCRP. AS1413 has been shown to retain
activity against MDR-positive leukaemia cells, and this could be a
reason for the observed difference in remission rates between the
AS1413 phase II trial and previous trials that used anthracyclines in
similar patients, where complete remission rates of 24% and 26% were
reported.
Treatment regimens based on AS1413 may be preferable to
anthracycline-based approaches in various settings where MDR
compromises anthracycline activity. The phase II trial reported at
ASH and the ongoing phase III trial of AS1413 have focused on
patients with secondary AML because this group represents a
significant unmet medical need, with a high prevalence of MDR and
poor outcome with standard, anthracycline-based regimens.
The phase III ACCEDE trial compares AS1413-based and
anthracycline-based regimens as remission-induction therapy for
secondary AML. It randomises 450 patients 1:1 to AS1413 plus
cytarabine or daunorubicin plus cytarabine. Recruitment is proceeding
rapidly, and data from the trial are expected in late 2010 or early
2011.
Bill Lundberg, MD, Project Leader for AS1413 at Antisoma, commented:
"We're very pleased with the support from physicians and patients
around the world for the ACCEDE study, which tests the idea of
replacing the anthracycline daunorubicin with the novel DNA
intercalator AS1413 as the partner for cytarabine in
remission-induction treatment of secondary AML. We hope that this
trial will build on the positive findings from our phase II study and
lead to the introduction of AS1413 as a new standard for the
treatment of secondary AML."
Glyn Edwards, Antisoma's CEO, added: "AS1413 has distinctive features
that could translate into real benefits for patients. We look
forward to seeing the phase III data in secondary AML and believe
that AS1413 could ultimately have potential in various blood cancer
settings."
An additional poster presentation given yesterday by Drs Ben Downie
and James Foran of the University of Alabama at Birmingham considered
whether certain karyotypes (different anomalies in the cancer cell
chromosomes) were predictive of patients' outcomes in the phase II
study. A monosomal karyotype, which has recently been found to
predict poor outcome in de novo AML patients, was found to have a
similar predictive value in the secondary AML patients studied in the
AS1413 phase II trial.
Copies of both posters are available on the Antisoma website at
http://www.antisoma.com/asm/products/as1413/
Enquiries:
Antisoma plc:
Glyn Edwards, CEO +44 (0) 7909 915 068
Daniel Elger, VP Marketing & Communications
Mark Court/Lisa Baderoon/Catherine Breen +44 (0)20 7466 5000
Buchanan Communications
Brian Korb/Seth Lewis +1 646 378 2923
The Trout Group
Except for the historical information presented, certain matters
discussed in this statement are forward looking statements that are
subject to a number of risks and uncertainties that could cause
actual results to differ materially from results, performance or
achievements expressed or implied by such statements. These risks and
uncertainties may be associated with product discovery and
development, including statements regarding the company's clinical
development programmes, the expected timing of clinical trials and
regulatory filings. Such statements are based on management's current
expectations, but actual results may differ materially.
About AML
AML is a type of cancer in which the bone marrow makes abnormal and
immature blood cells, eventually leading to bone marrow failure. The
American Cancer Society estimates that there will be around 13,000
new cases of AML diagnosed this year in the US alone. Antisoma
estimates that 3,000-5,000 of these patients will have secondary AML
(AML evolving from a myelodysplastic syndrome or following
chemotherapy or radiotherapy treatment for other cancers).
About AS1413
AS1413 (amonafide L-malate) was added to Antisoma's pipeline through
the acquisition of Xanthus Pharmaceuticals, Inc. in June 2008. AS1413
is a novel DNA intercalator that induces apoptotic signalling by
blocking topoisomerase II binding to DNA. This differs from the
action of classical topoisomerase II inhibitors, which induce
apoptosis by causing extensive DNA damage. A further distinctive
feature of AS1413 is its ability to evade Pgp and related
transporters responsible for multi-drug resistance (MDR). A pivotal
phase III trial is evaluating AS1413 as a treatment for secondary
AML, a condition often associated with MDR. This follows a phase II
trial in the same population, from which final data are reported here
and earlier data have been presented at conferences including the
2008 ASCO and ASH meetings. Antisoma is developing AS1413
independently and plans to commercialise the drug itself in the US
while seeking partnerships for commercialisation in other
territories.
About Antisoma
Antisoma is a London Stock Exchange-listed biopharmaceutical company
that develops novel products for the treatment of cancer. The Company
has operations in the UK and the US. Please visit
www.antisoma.com for further information about Antisoma.
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