The bystander effect
is not to be underestimated," agreed Nidal Najjar Daou, a behavioral psychologist and an assistant professor at the American University of Beirut.
Additionally, several subjects in the responsive group also exhibited one or more indicators of the bystander effect
(spontaneous regression of untreated tumors after PV-10 treatment of other tumors), including the first evidence of regression of visceral metastases in two of five subjects in this group who had documented visceral metastases at enrollment.
Dr Peter Fischer said, 'The classical bystander effect
was replicated when the situation involved low potential danger, but not when the situation involved high potential danger.
Not all cancer researchers have observed this bystander effect
, notes Larry M.
The mechanism by which PV-10's bystander effect
is produced was investigated using hepatocellular carcinoma (HCC) and melanoma tumors in immunocompetent and immunodeficient mice.
A third poster presentation (Abstract 1470), entitled Ad-ISF35 Intratumoral Administration Induces a Bystander Effect
and Immune-Mediated Tumor Rejection with a Safe Vector Biodistribution and Toxicology Profile In a NHL Mouse Model, described results from a preclinical study showing that Ad-ISF35 injected directly into the tumors of mice bearing subcutaneous NHL breaks tumor tolerance and induced complete tumor regression and immunity to tumor rechallenge.
Agarwala continued, "The bystander effect
, which appears to result from an immunologic response stimulated by PV-10 chemoablation, is especially intriguing.
New and emerging areas such as molecular imaging in evaluating the response and resistance to targeted radiotherapy, a discussion of the bystander effect
which may enhance its effectiveness, and the potential of combining cytolytic virus therapy with targeted radiotherapy have also been included.
PV-10's bystander effect
is further evidenced with the encouraging and corroborative data on visceral metastases presented at ASCO.
First Evidence Of Bystander Effect
On Visceral Metastases--
Further, to our knowledge PV-10 is the only intralesionally delivered agent that has been repeatedly demonstrated to induce removal of remote, untreated tumors through a bystander effect
We are extremely pleased about the opportunity to present an update on our development efforts with PV-10 for metastatic melanoma, including interim data from the current Phase 2 study involving the first 40 subjects in the trial, in particular data on safety and efficacy and the bystander effect
," said Craig Dees, PhD, CEO of Provectus.
In this initial cohort, up to three target lesions were injected in each subject, with up to 3 additional nontarget lesions remaining untreated for observation of a bystander effect
All subjects received a single treatment of up to 20 lesions, while up to 3 untreated lesions were observed for evidence of the potential bystander effect
The bystander effect
is the inhibition of growth or complete removal of remote tumors after intratumoral ablation of one or more other tumors using PV-10.