which invaders to attack. Fusing them with tumor
cells “trains” the dendritic cells to recognize tumors;
when they are returned to the body, the dendritic
cells can mobilize T cells to attack. Early results of
this approach are promising: In December 2016,
Rosenblatt’s group reported that 12 of 17 patients
treated with a dendritic cell vaccine for AML
remained free of disease recurrence after five years.
Rosenblatt’s group also fused dendritic cells with
tumor tissue to develop the multiple myeloma vaccine
that Liebert received in 2007. Before he began the stem
cell transplant, Liebert underwent a bone marrow
aspiration, which meant removing tissue from his
iliac crest—the ridge of bone at the top of the hip. The
vaccine recipe called for about two tablespoons of
tumor tissue. Liebert was conscious for the procedure.
“It felt like getting kicked by a mule in your back,” he
recalls. Producing the vaccine took about three weeks.
As a phase II study, the trial was designed to show
that the vaccine, administered after a stem cell transplant, was safe and effective, which it was. Liebert never
learned about his specific results, but Rosenblatt and
her team reported in 2013 in the journal Clinical Cancer
Research that 31 percent of patients had a complete
response—which means no detectable signs of cancer—
after the stem cell transplant. That number jumped to
nearly 50 percent after receiving the vaccination.
“I wish they had been able to tell me if I had a clinically significant response,” he says, but the results
weren’t provided to participants in the trial. (Some
clinical trials do provide results to participants.)
Whether or not he was in the group that responded
to the vaccine, he did have a long stretch without
symptoms. “For two solid years after the trial, I was
clean as a whistle.”
The results of that trial set the stage for a bigger
one: Over the past year, researchers from 15 cancer
centers in the United States traveled to Beth Israel
Deaconess to learn how to synthesize dendritic cell
vaccines. They are now collaborating on a national
phase II trial of the vaccine for multiple myeloma
patients. Rosenblatt hopes the study will help an
even larger swath of the patient population.
COMBINING VACCINES WITH OTHER TREATMENTS
The real clinical value for vaccines is likely to be as
part of a combination therapy that includes other
types of treatment.
In the glioblastoma trial that Gilbert oversees at
the NCI, for example, patients receive both a vaccine
made from proteins taken from their own cancer
cells and a checkpoint inhibitor, a type of immunotherapy that effectively releases the brakes on the
immune system. The vaccine reveals the tumor;
the checkpoint inhibitor activates T cells to attack.
Gilbert and other researchers hope this strategy can
overcome the tumor’s strategies for suppressing the
“Imagine this huge army going in there, and if
you find some resistance, you just overwhelm it,”
In the case of the multiple myeloma vaccine,
researchers suspect the experimental dendritic cell
vaccine extends the benefits of stem cell transplants,
THE REAL CLINICAL VALUE FOR VACCINES IS LIKELY
TO BE AS PART OF A COMBINATION THERAPY THAT
INCLUDES OTHER TYPES OF TREATMENT.
LOOKING WITHIN FOR CANCER TREATMENT