DR EISENBERGER: Cabazitaxel is associated with an incidence of neutropenic fever at the 25 mg/m2 of about close to 9%. And it’s actually being observed in the current trial as well. So, what I do is, intuitively, if I had a patient who’s received extensive prior chemotherapies, he had extensive disease, already shows some signs of bone marrow failure or had some incidents of neutropenia, received prior radiation therapy, if they’re getting the 25 mg/m2 dose, then I would give him the growth factor associated with treatment up front.
DR LOVE: How about age?
DR EISENBERGER: Not necessarily. I don’t think age is necessarily a risk factor. I mean, we do see today patients with castrate-resistant disease who don’t have a lot of disease and haven’t received a lot of prior chemotherapy and they’re otherwise not high risk, and they tolerate chemotherapy quite well. I would wait to see what happens after 1 cycle.
DR LOVE: So what’s the current question you’d like to see the group address?
DR EISENBERGER: What would you predict for response to cabazitaxel? Are we in a position to actually choose a treatment with chemotherapy or no chemotherapy based on the data that we have available?
It’d be interesting to see what the group feels. When do they use cabazitaxel? Any other chemotherapy regimen as second-line following docetaxel?
DR SLOVIN: A lot depends on whether or not patients who have had docetaxel have significant neuropathy, because if they have neuropathy I can’t put them on cabazi because they’re just preemptive. I haven’t used mitoxantrone in a very long time, but what I will do for some of these people, if there’s no clinical trial available — but if there is one, let’s say, with XL184, that would be my next choice. But if not available then I would be considering a weekly treatment with carboplatin, either alone or in combination with others. It all depends on the neuropathy, because a lot of what we do are microtubular inhibitors these days, even the antibody-drug conjugates that we have now. ASG-5ME has a taxane or microtubular inhibitor in there, too.
DR SARTOR: It’s interesting. In the TROPIC trial, there were a couple of things — and this is a forest plot analysis, which is retrospective. But for patients who progressed very rapidly on docetaxel, they really did not do very well on cabazitaxel either. On the other hand, for patients who seemed to have been on a long duration of the docetaxel and then they progressed, and then they went on the cabazitaxel, they actually did quite well. So one might be able to risk-stratify patients a bit by the durability of their initial treatment with docetaxel. And the patients who do well on chemo, turns out you can switch them over to another chemo and do pretty well. And I think this is a bit analogous to the hormonal therapies, that the patients who do well on 1 hormone might do well on another. But it’s a little more limited subset, of course, because you have to have a good performance status and you’ve got to monitor, and you do have to be aware of the neutropenic issues, et cetera.