Well, once again it appears disappointment has resulted in what is probably a preferable alternative. A mandatory step in CAR-T protocols is lymphodepletion with conventional chemotherapy (Cytoxan/fludabarine) prior to the reinfusion. Last time around it took a good 6 months for my bone marrow to mostly recover, and it seems plausible to me that the qualification “mostly” is the reason for the “out of spec” designation (nobody here knows if that means insufficient numbers or insufficient activity) for my newest CAR-T cells. I’m not the first Mayo Carvytki recipient to have this issue. Avoiding that hit is itself alone perhaps a good reason to choose a bispecific antibody over CAR-T, so, again, the Mayo’s CAR-T expert seemed pretty happy to recommend the switch now that they’ve finally ramped up the Tecvayli protocol for several weeks now.

On Day 1, March 27th, I will receive a tiny SQ dose. The Mayo experience already has been that daily outpatient monitoring is sufficient to detect the expected mild Cytokine Release Syndrome or neurologic toxicity, most of which can be treated from the clinic. My relatively small tumor burden and low lymphocyte count (thanks a lot Cytoxan back in September) might well predict milder toxicity anyway. If all goes well on Day 4 I’ll get a small dose with further monitoring. The first full dose comes on Day 8, repeated every week after, with the option of dose adjustment if there are any problems (unlikely after day 15), something that is harder to do with CAR-T. We should see some response by the second month. The great concern from then on would be infections, but I won’t really be much more immunosuppressed than I’ve been since 2019.

Again, because we’re still targeting BCMA the chance of success is probably only about 50/50, but if we just buy a few months of response there are other bispecifics in the pipeline targeting other antigens on the myeloma plasma cell, with FDA approval possible by summer, even if I lack sufficient renal function to get into research protocols. I am again cautiously optimistic, which was an attitude difficult to maintain the last several months.