Study on Intralesional Rose Bengal out of Moffitt...we know a bit more about HOW it works!!!

In 2013 I wrote this:  "I first wrote about PV-10 (also known as Rose Bengal, a pretty cheap derivative of fluorescein, that has been used for over 80 years to stain necrotic tissue in the cornea when corneal abrasions are suspected and as an IV diagnostic of liver impairment) being used in melanoma patients in October of 2012.  The study I reported on was one in which Stage 3-4 melanoma patients had up to 4 courses of PV-10 injections into up to 20 cutaneous and subcutaneous tumors.  The cool thing was that not only did many of the injected tumors respond and shrivel, but some tumors at distant sites (even in the lungs) that were NOT injected, shriveled as well!!!"

And this in 2014:  "Intralesional melanoma therapy (A procedure in which the "treatment" is directly injected into superficial tumors and in theory, not only does that tumor die, but "by stander" tumors at more distant sites die too!!!) was first recorded back in 1975.  A 75 year old male with 64 melanoma mets just below the skin, as well as junk in his lungs, had 17 superficial lesions injected with Bacille Calmette-Guerin over a period of 8 months. (BCG is a vaccine against some strains of tuberculosis, but does contain a weakened version of the bacteria itself within it.) In the end, all 17 tumors injected resolved and his pulmonary mets diminished by more than 50%!  However, enthusiasm for BCG as a melanoma treatment waned as patients in subsequent trials experienced anaphylactic reactions and death due to disseminated BCG, and randomized trials failed to replicate significant clinical benefit.

Later, intralesional therapy was tried using all sorts of things.  More recently Allovectin-7, OncoVEX, and PV-10 have demonstrated positive results, killing melanoma at the injected site and systemically.  [Now we also have CAVATAK, an intralesional derived from the Coxsackievirus:  CAVATAK: intralesional therapy derived from the Coxsackievirus]

Allovectin-7, is a soup of DNA, that attempts to change the gene make-up of tumor cells. In a study reported in 2012, it provided a 12% overall response rate with no grade 3 or higher toxicities in patients with stage III/IV melanoma with injectable cutaneous lesions.

OncoVEX is a 2nd generation herpes virus embedded with GM-CSF...a substance that causes the body to make more white cells. (GM-CSF can be given to premature babies and leukemia patients with low white cell counts to help build them back up....and reverse immune suppression.) But, in OncoVEX, it is thought to only replicate in the tumor cells.  The white cells produced in the process kill off the tumor cells.  In a phase 2 trial reported in 2012, 20% of patients achieved a complete response and 28% gained an overall response.  92% of the responses were durable to at least 6 months, and the majority were ongoing with a range of 18-40 months.  Responses were found in patients with all stages and systemic tumors were eradicated in some patients.

Rose Bengal was first utilized in the 1800's to dye fabrics and color the feet of Bengali women red for weddings and celebrations. Later it was used as a staining agent to find corneal lesions and then as an IV preparation to check for impaired liver function.  The "Aha!" moment came in the 1980's when Japanese tests of a "food dye" to determine tumor origin, found dose-dependent survival increases. After a few other sundry studies....PV-10 was born.  It is a 10% Rose Bengal solution, with a 30-minute half-life, excreted via bile. PV-10 is excluded from normal cells, but slips through the cell membrane of cancer cells (liver, breast, melanoma, and others) because their cell walls have a higher lipid content. Once inside, PV-10 triggers lysosomal release (the part of the cell that digests waste), killing the cell in 30-60 minutes. Antigenic tumor fragments are believed to produce the 'bystander effect' leading to immediate reduction in tumor burden and concomitant immunologic activation."

Here is a link to the entire report and others I've posted here:  Info from ASCO 2014 on Rose Bengal (PV-10) and links to more reports

And now....researchers have learned a little more about how it actually works....

Intralesional rose bengal in melanoma elicits tumor immunity via activation of dendritic cells by the release of high mobility group box 1.  Liu, Innamarato, Kodumudi, Weber, et al.  Oncotarget. 2016 May 9.

"Intralesional (IL) therapy is under investigation to treat dermal and subcutaneous metastatic cancer. Rose Bengal (RB) is a staining agent that was originally used by ophthalmologists and in liver function studies. IL injection of RB has been shown to induce regression of injected and uninjected tumors in murine models and clinical trials. In this study, we have shown a mechanism of tumor-specific immune response induced by IL RB. In melanoma-bearing mice, IL RB induced regression of injected tumor and inhibited the growth of bystander lesions mediated by CD8+ T cells. IL RB resulted in necrosis of tumor cells and the release of High Mobility Group Box 1 (HMGB1), with increased dendritic cell (DC) infiltration into draining lymph nodes and the activation of tumor-specific T cells. Treatment of DC with tumor supernatants increased the ability of DCs to stimulate T cell proliferation, and blockade of HMGB1 in the supernatants suppressed DC activity. Additionally, increased HMGB1 levels were measured in the sera of melanoma patients treated with IL RB. These results support the role of IL RB to activate dendritic cells at the site of tumor necrosis for the induction of a systemic anti-tumor immune response."

Bentie has always believed that dendritic cells are going to hold some important keys to understanding and perhaps treating melanoma!  Way to go ratties (and little melanoma-bearing mice)! - c