Dear Aimeth,
There are various ways of referring to response: partial response, complete response or stable disease.
In some clinical trials, drugs can actually be approved if they show something like 20% response. The big questions are how the treatments may effect long term survival and whether there is a balance in the risk vs. benefit ratio.
Since MVCA is a toxic and no doubt expensive treatment they probably need to justify continuing to use it. I would hope that they would not continue a treatment that didn't show response, but have seen the opposite occur as well. When we questioned my step father's doctor why they were continuing chemo while the cancer was growing the response was "It's unethical to withhold treatment if the patient asks." But we said to ourselves, "Isn't it unethical to subject a person to toxic treatments that aren't working?" But in this case it came down to patient preference, my step father wanted to go out fighting and there were no other chemos for his cancer (malignant melanoma).
There are other drugs being tried for blc, if your husband doesn't respond to MVAC and is wants to try something else. The most important thing is to be in decent general condition otherwise, aside from the cancer. If not, most oncologists will hesitate to enlist a person in a clinical trial or take non-standard approaches.
Perhaps a private talk with your husband's doctor about what options he would suggest in case MVAC poops out. There are some things covered in our "metastatic' page:
blcwebcafe.org/metatcc.asp
Wishing you the best with everything,
Wendy