Blastic Plasmacytoid Dendritic Cell Neoplasm (BPDCN) Study

I learned from an email that Blastic Plasmacytoid Dendritic Cell Neoplasm (BPDCN) is also called Plasmacytoid Dendritic Cell Leukemia (PDCL). It's been called a lot of things in the past, including Blastic Natural Killer Cell Lymphoma, which is a pretty cool name for a very "uncool" disease.

Anyway, I wanted to summarize a study published about 6 months ago, on November 30, 2012. It was published online at that time, then published in Blood Journal on Jan. 8, 2013. You can read the whole study on that link.

Thank you to Michael Oldtree for posting the link on rareshare.org for other BPDCN patients.

Basically, Damien Roos-Weil et al analyzed 34 BPDCN patients who had received stem cell/bone marrow transplants from a sibling or unrelated donor.

The blood cells. The cell that stopped maturing, then multiplied uncontrollably, determines the type of leukemia. Notice the difference between Myeloid and Lymphoid cells, which makes the difference between Myeloid and Lymphoid Leukemias. The Plasmacytoid Dendritic Cell is a myeloid cell, which may be why BPDCN is treated like AML.

Here's the results, short and simple:

1. This was an analysis of treatment results, not a study where the researchers treated the patients themselves.
2. Ages were between 10 and 70 years old.
3. They separated the patients into two groups, those under 42 and those over 42.
4. There was no significant difference in survival rates between the older and younger group.
5. The sample size was only 34 people. The disease is quite rare, and there have only been about 200 cases ever.
6. The disease-free survival rate at 28 months was 50% for those that received a full-strength preparatory regimen.^*
7. All of those who received a reduced intensity preparatory regimen died of complications or relapse.^*

^*A full-strength preparatory regimen, by the study standards, was at least 8 Gy of radiation and at least 10 mg/kg of bisulfan or 150 mg/m2 of melphalan. Anyone who gets a bone marrow/stem cell transplant is told whether they are receiving full-strength (myeloablative) or reduced intensity (non-myeloablative) conditioning.

Discussion of Results

The encouraging thing in this study is that BPDCN, that used to be known as having a 0% survival rate may possible have a 50% survival rate, if the patient is healthy enough to withstand a myeloablative marrow transplant.

The discouraging thing is reading that none of the patients they looked at who received reduced-intensity conditioning survived. They all died of relapse or complications. The sample-size for the reduced-intensity patients was very small (10, I think).

The study calls for more research on the ability of the new immune system (a new immune system is one product of a marrow transplant) to destroy any leftover leukemia and prevent relapse. This is called Graft-vs.-Leukemia, and they would study this by examining relapse rates for patients who received non-myeloablative conditioning. They would also study the relapse rates for all transplant recipients based on how much Graft-vs.-Host they experienced.

Graft-vs.-Host means that the new immune system is attacking the patient's body, which happens pretty often because the immune system and the patient's body have different DNA. (Yeah, the DNA of my blood is different than the DNA of my skin.) GVH is a bad thing in one sense, but it's also a good thing in most types of leukemia. An immune system that is aggressive like that is more likely to find and destroy any leftover leukemia cells that managed to survive the chemo and (sometimes) radiation used to prepare the patient for transplant. Thus, the relapse rate among leukemia patients in general is lower for patients that experience a small amount of GVH. A large amount of GVH is life-threatening, and dying is no good way to prevent relapse!

This study is saying, however, that they don't have evidence that Graft-vs.-Leukemia is effective in BPDCN patients, though they don't have a big enough sample size to confirm ineffectiveness. And that is a question we really need to answer! There is no sense putting patients through non-myeloablative transplants if they are not going to be effective. Of course, how are we going to find out if we don't try. Usually, non-myeloablative transplants are only used on older or weaker patients who might be killed by full-intensity regimens.

One final note: I'm not actually a BPDCN patient. I was diagnosed with BPDCN by a lab in California. The lab at Vanderbilt Cancer Center, however, was not willing to confirm the diagnosis. They could not come up with an alternative, either. They ended up calling my leukemia "undifferentiated," which means, in my case, they really didn't know what it was. They treated it like they would BPDCN, which means that I got a chemotherapy designed for Acute Myeloid Leukemia (AML) and a fully myeloablative marrow transplant was required as soon as I got into remission. Waiting any longer than 6 to 9 months would have just about guaranteed a drug-resistant relapse that would prove fatal. (Due to complications, we had to wait 6 months, and everyone was in a hurry at that point.)