By Deena Beasley
March 6 Treating HIV patients first with a
chemotherapy drug improved their response to an experimental
gene-modifying technique for controlling the virus, according to
The company presented new data from a small early-stage
trial of its treatment, SB-728-T, on Thursday at the Conference
on Retroviruses and Opportunistic Infections in Boston.
Shares of Sangamo were up 17 percent at $22.92 in late
trading on Nasdaq. Shares of the Richmond, California company
have gained about 67 percent so far this year.
On Wednesday, the New England Journal of Medicine published
data from an earlier trial showed that Sangamo's strategy of
genetically modifying cells from people infected with HIV could
become a way to control the virus that causes AIDS without using
"Sangamo's HIV 'suppression' is promising, but very early
and far from a 'cure,'" RBC Capital Markets analyst Michael Yee
said in a research note. "This is very early study for
technology and safety validation."
The technique is designed to disrupt a gene, CCR5, used by
the human immunodeficiency virus to infect T-cells, the white
blood cells that fight viral infections. A patient's cells are
removed and processed to alter the DNA that codes for the CCR5
receptor. The altered cells are multiplied and tested, then
infused back into the patient.
The results presented on Thursday show that increasing doses
of the chemotherapy drug Cytoxan, or cyclophosphamide, before
infusion with SB-728-T led to an improvement in both growth of
the genetically modified cells and an increase in total CD4
immune system cells, which otherwise would be a target for HIV,
according to Sangamo.
Two of three patients treated with the highest Cytoxan dose
have remained off of antiretroviral drugs for several weeks with
detectable, but stable, levels of HIV in their blood, the
company said. In all, nine patients received Cytoxan to augment
Cytoxan, made by Bristol-Myers Squibb, is used to
reduce the number of T-cells in the body, which then rapidly
repopulate once the drug is discontinued. The aim is to allow
SB-728-T to be infused as new T-cells are growing in the body.
Cytoxan is generally used to enhance effectiveness of bone
marrow transplants in cancer patients and as therapy for
The gene editing technique behind SB-728-T seeks to mimic
the resistance to HIV observed in the small number of people who
have inherited CCR5 mutations from both parents.
Sangamo has also been carrying out clinical studies in HIV
patients who have one copy of the natural mutation.
So far, the company has used a deactivated virus to deliver
its gene-modifying technology to patients but said it will shift
to a new method using messenger RNA to deliver the cell-altering
proteins. Messenger RNA is a single-strand molecule that carries
information telling cells which proteins to make.
When a virus is used to deliver gene therapy, patients
develop antibodies, making them immune to further treatments. By
using messenger RNA, patients can be re-treated with SB-728-T if
needed, said Sangamo spokeswoman Elizabeth Wolffe.
Sangamo said it has expanded the Cytoxan preconditioning
study to determine the right dose of the chemotherapy. It then
plans to treat an additional 12 subjects, using the new
messenger RNA delivery method, this year.
"If those data are positive, plans are to move forward with
pivotal trials with a pharma partner," said Sangamo Chief
Executive Officer Edward Lanphier, referring to efforts to sign
on a bigger drugmaker to help with funding. He did not give
details on whom Sangamo might approach.
Sangamo is testing its "gene editing" strategy to develop
therapies for a number of diseases, including inherited
illnesses such as hemophilia, sickle cell disease and