Dear all,
I recently came across the below study, which I thought was rather interesting:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5620172/
The authors used incrementally higher dosages of Doxycycline (12.5 uM, 25 u.M, 50 uM) in vitro on cancer cells in an effort to create metabolically inflexible cells and to test whether these would be then be more sensitive to metabolic inhibitors, including natural agents (Vitamin C and Berberine) and various meds (Atovaquone, Irinotecan, Sorafenib, Niclosamide, Chloroquine, and Stiripentol).
The cancer cells in the study ended up being highly sensitized to some of these agents, for example Vitamin C (4-10 x more sensitive), Berberine and Chloroquine. It's noteworthy that, following Docycycline treatment, cells became sensitive to Vitamin C at a dosage level which is reachable orally (IC-50 = within the range of 100uM - 250 uM). My understanding is that newer Vitamin C formulations using oral Liposomal delivery (e.g.: https://www.livonlabs.com/cgi-bin/start.cgi/liposome-encapsulated/lypo-spheric-vitamin-c.html) can reach concentrations of up to 400 uM in the blood, a level at which cell elimination in vitro was in excess of 90%).
I'm curious if these results could be replicated at least directionally in a human setting, as it would be a rather cost effective and non-toxic approach. Any thoughts?
A few questions I'd have for example are:
1. Is this Doxycycline cell sensitization replicable in a human setting? If so, at what dosage?
2. Is there any chance an oral Vitamin C formulation (e.g. Liposomal) could replicate the effect seen in vitro? Alternatively, I presume IV infusions would do the job?
3. Which of the other agents would be the most feasible otherwise?
Best regards,
John
Standard oral doses of doxycycline according to drugs.com are 100 mg once or twice daily. Even at double the standard dose (200 mg twice daily), mean cerebrospinal fluid concentrations reach 1.3 mcg/mL (or ~ 3 micromolar).
ReplyDeletehttps://www.ncbi.nlm.nih.gov/pubmed/3834836
It would be difficult to translate to humans the in vitro study of doxycycline resistance which used 12.5 to 50 micromolar (or 4 - 17 times the maximum CSF concentration at double the standard dose).
I wouldn't trust in vitro assays of vitamin C toxicity, as there are factors in the blood that can neutralize it's pro-oxidant effects. In the only published clinical trial of ascorbate for brain tumors, the target plasma concentration specified (presumably to ensure pro-oxidant rather than anti-oxidant effects) was 20 millimolar (mM), which was achieved in all subjects with an 87.5 gram intravenous infusion of ascorbate (vitamin C).
https://www.ncbi.nlm.nih.gov/pubmed/28366679
In mouse studies no amount of oral vitamin C could achieve pro-oxidant concentration is tissue, intravenous injection was required for that. Vitamin C during radiation is a bit risky because depending on the concentrations achieved, vitamin C could have protective effects, rather than sensitizing effects on tumor cells.
As an aside, I rarely pay more than passing attention to in vitro studies, since almost all in vitro work with repurposed drugs and supplements use grossly overinflated drug concentrations relative to what is achievable in the body. Sometimes 100 - 1000x or more inflated. Furthermore I suspect that even when in vitro work is validated in mice, the primary mechanisms of action in vivo might be different from the ones identified in vitro.
Thanks, Stephen. I was particularly curious about this study as I've just started taking Docycycline as part of the CoC protocol. I'm also currently doing Immunotherapy treatment at the IOZK in cologne, and as part of the treatment receive regular IV Vitamin C (I'm not sure about the dosage though - I will have to check). I thought it could make a neat additional angle to the treatment cocktail perhaps... but completely see your point about in vitro studies such as this one.
DeleteStephen, I'm thinking about the dose of vitamin C and in this study I see that the plasma concentration 20 millimoles was with a dose of 62.5 grams of ascorbate (Figure B). Or am I misunderstanding this picture?
DeleteAlso from picture A it follows that the optimal dose of ascorbate was from 15 to 50 grams. Although the number of patients is very small to draw any conclusions.
In figure 7B on page 11, some people achieved the target plasma concentration of 20 mM with a dose of 62.5 grams and some didn't.
DeleteThe text on page 8 says "The desired mean therapeutic
blood level was achieved in all subjects receiving the 87.5 g in-
fusions". This is somewhat confusing as figure 7B shows that for the 87.5 gram dose, the 25th percentile for plasma ascorbate (the bottom of the box) is below 20 mM. Same for all the doses between 62.5 grams and 100 grams.
It's not possible to say that the two patients with the longest PFS were receiving optimal doses of vitamin C. They may have simply had the most complete resections or the smallest tumors etc.
Stephen, I am interested in this particular line from your comment above
Delete"Vitamin C during radiation is a bit risky because depending on the concentrations achieved, vitamin C could have protective effects, rather than sensitizing effects on tumor cells."
Would it be unwise to do any type of Vitamin C infusions while undergoing treatment or would this be a risk only during radiation?
I ask because a naturopathic doctor we have consulted with recommended doing vitamin C IV therapy and IV ozone therapy during treatment or after.. but perhaps it would be safer and more beneficial to undergo this after as a way for the body to repair after treatment (chemo/radiation).
He said these treatments aim to increase amount of oxygen to the area as well as the amount of minerals and electrons to the area - which he believed would create an environment in which the cancer cells would be less likely to survive.
Ozone Therapy
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC442111/
Vitamin C therapy
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6162462/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6115501/
Excerpt from this paper below:
"Cell culture studies have shown radio-sensitizing effects of high dose vitamin C in combination with ionizing irradiation (Shinozaki et al., 2011; Herst et al., 2012; Hosokawa et al., 2015). Only a few studies have been carried out in animal models, with most showing radio-sensitizing effects of vitamin C (Du et al., 2015; Cieslak et al., 2016), although one model showed radio-protective effects (Grasso et al., 2014). These differences likely reflect the timing of the radiation treatment relative to vitamin C administration. For example, in the Grasso et al. (2014) study, radiation treatment was carried out only 2 h after intraperitoneal administration of vitamin C, while in the other studies radiation treatment was carried out on days 3 or 5 following initiation of high dose vitamin C administration (Du et al., 2015; Cieslak et al., 2016). In these latter studies, high dose vitamin C administration was shown to act synergistically with radiotherapy, decreasing tumor growth and enhancing survival (Cieslak and Cullen, 2015; Cieslak et al., 2016)."
" Does IVC interfere with chemotherapy or radiotherapy? Clinical trials indicate that IVC does not adversely interfere with chemotherapy and pre-clinical studies indicate that it may in fact act synergistically in combination with different chemotherapeutic agents. There is as yet limited research around interference with radiotherapy, with conflicting results likely due to the timing of the interventions."
It seems that it may be more beneficial to do the vitamin C infusions at least a few days before receiving radiation. Thoughts?
My comment that you quoted was based on the study by Grasso et al.
Deletehttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC4266032/
Pharmacological Doses of Daily Ascorbate Protect Tumors from Radiation Damage after a Single Dose of Radiation in an Intracranial Mouse Glioma Model
The authors of the review you quoted from believe the conflicting results in animal models (some showing radiosensitizing, some showing radioprotection) may be due to the timing of the radiation and vitamin C administration relative to each other. This is a hypothesis, but not necessarily the correct interpretation (it may or may not be). I have assumed that dosing was also a very important factor - you need to reach a certain threshold of ascorbate in order to ensure the generation of hydrogen peroxide radicals, for vitamin C to have a pro-oxidant rather than anti-oxidant effect.
The main human evidence we have for IVC as a treatment for GBM is in this paper:
https://www.ncbi.nlm.nih.gov/pubmed/28366679
Correspondence: douglas-spitz@uiowa.edu (D.R.S.), bryan-allen@uiowa.edu (B.G.A.)
Perhaps you could try contacting these authors for more specific ideas around dosing and scheduling, or you could attempt talking to some of the people running the various clinical trials of IVC for brain tumors:
https://clinicaltrials.gov/ct2/show/NCT02344355
Contact: Bryan G. Allen, MD, PhD 319-353-8836 bryan-allen@uiowa.edu
Contact: Joseph J Cullen, MD 319-356-1616 joseph-cullen@uiowa.edu
https://clinicaltrials.gov/ct2/show/NCT01752491
Principal Investigator: John M. Buatti, MD Department of Radiation Oncology, The University of Iowa
Study Director: Joseph J Cullen, MD Professor of Surgery, The University of Iowa
https://clinicaltrials.gov/ct2/show/NCT02168270
Principal Investigator: Nicole Shonka University of Nebraska
Thank you, I might look into this later on. For the time being our Naturopath advised us to avoid the Vitamin C infusions during radiation/chemo and suggested Hyperthermia treatments along with Mistletoe injections during the chemo/radiation period.
DeleteMany in their cocktail use doxycycline or minocycline. But in this article
ReplyDelete2017 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5584825/
it is written that:
"Importantly, NAC (N-acetyl-L-cysteine) or vitamin C significantly reversed the anti-proliferative and pro-apoptotic effects of doxycycline in U87 and A172 cells (Figure 4B, 4C and Supplementary Figure 2B, 2C), suggesting that oxidative stress was required for the action of doxycycline in glioblastoma cells."
Thus, it will be counterproductive to combine doxycycline (or minocycline) and intravenous vitamin C?
Good find, Semyon. I think the point with Vitamin C is that it can be either anti-oxidant or pro-oxidant (i.e. further increasing ROS) depending on the dosage. Probably best if Stephen comments on possible implications here.
DeleteSee my comment above. Realistic concentrations of doxycycline in the central nervous system are 3 micromolar (at double the standard drug dose) or less. The study you pointed out uses 40 micromolar doxycycline with or without NAC (figure 4). Clinical relevance of this study might be very limited for that reason.
Delete