Hi Bills,
I am like you and many other patients who are trying to learn a little more about our bladder cancers hoping to give the best chance to our own bodies. Like I said if your father is being treated at a reputable hospitable with a urology department and if he is under the care of an experienced and well-versed with the current research on bladder cancer, you had given your dad the best chance already. Also please keep in mind that most of the participants in the forum are like amateur detectives. We are not here to give any medical advice. There will be mistakes and misinformation So, please take it with lots of grains of salt.
First of all, there have been several studies on the efficacy and the side effects of the reduced dose of BCG, which your urologist is considering. I think the trial which is more relevant to the case of your dad was done by European Organisation for Research and Treatment of Cancer - genitourinary cancers group (EORTC-GU) involving over 1300 intermediate- and high-risk Ta, T1 papillary carcinoma of the bladder. I say it is more relevant is because the BCG strain the patients were treated was TICE strain by MERCK, which the patients in the US and Canada are also treated with. Onco-Tice vial comes in 50mg. What I have noticed in other similar studies involved different strains and also the full dose was 80 mg or 90 mg. Some studies reduced to 1/2 dose. A 1/2 dose of 80mg BCG is 40mg which is 80% of 50 mg, which Onco-Tice comes with. But, we have to recognize that other studies gave other insights, which EORT-GU did not address. What is common among various studies is that most BCG Intolerance by side effects happen in the first 6 weeks induction course and the first 3 weeks maintenance course. Incidentally, this coincides with what a urologist I know explaining to other urologists and post-doc residents in the internal lecture series of their urology department.
Anyway, according to the clinical trial by EORTC-GU, the good news is that 1/3 dose and full dose have similar efficacy. The concerning finding is that there are not many differences in the side effects between the 1/3 dose group and the full-dose group. So, there may be a chance that your dad will experience similar side effects at some point even if the dose is reduced to 1/3 given. One difference is that your dad experienced right after the 5th treatment, but the maintenance is 3 doses in 3 weeks, then 3 or 6 months rest. Also, this clinical trial involved only BCG naive ( those who were treated with BCG for the first time) patients, but your dad's case is re-introducing BCG after the initial BCG intolerance. Also, the next treatment is only 3 weeks. So, so many parameters are different. Anyway, I think the urologist will approach the reintroduction of BCG carefully. As there have been suggestions of reducing further the dose so a patient can continue the BCG treatment. Below is what Dr. Lamm, a well-known figure for BCG treatment says about BCG reduction.
blcwebcafe.org/drlammsprotocol
In terms of MTB, it will likely require gene sequencing of your dad's tumor. Your hospital may have access to DNA sequencing equipment by the company called Illumina. It used to cost $1M to do the genome sequencing of a human, but I have read that the cost has come down substantially to less than $1,000. I know one bladder cancer patient used the company called FOUNDATION to do the gene analysis. The company's website says the test checks mutations of cancer-causing genes in addition to MTB.
www.foundationmedicine.ca/pdf/FMI%20-%20FoundationOne%20Technical%20Information%20and%20Gene%20List%20A.pdf
But, please note that the study by Dr. Meeks has a very small cohort and the report says that it needs further study with a much larger cohort to validate the result of his study that MTB is a factor for progression.
Having said that, bladder cancer is known to have high MTB among all types of cancers, the third following melanoma, lung cancer. One idea is that cancer with high MTB produces a high number ( different kinds) of antigens and gives the immune system the opportunity to pick up some of them and deliver them to lymph nodes and activate T-cells, which give our immune system to kill cancer cells. So, immune checkpoint inhibitor immunotherapy is shown to work better for the cancer types with high MTB such as melanoma, lung cancer, and bladder cancer.
genomemedicine.biomedcentral.com/articles/10.1186/s13073-017-0424-2
Some people expect that genome analysis for diagnosis and selecting the right treatment for bladder cancer will be applied not so far distance in the future. Hope it will come soon.
What's going on in our body is so complex. So, I do not think we can expect any simple factor, even MTB, to lead us to the solution. It is just one of many parameters in order to solve the mystery of our body.
best