Double Trouble

The tumor load in my peripheral bloodstream doubled over the past 3 weeks.  I had a FACS done on August 31st, and the report indicated the percentage of hairy cells increased to .04% from .02%. If the cells are really doubling every three weeks, then I'll have an appreciable burden (around 1%) by January.  Currently, about 5% of my lymphocytes are hairy cells.  I just got the flow results today and haven't talked to Dr. K yet about what it all means.  Still, I've asked to have another flow on Sept. 21st.  If the burden doubles yet again, then I'd like to get another bone marrow biopsy in early October to see if the cells are back in the core.

On the bright side, my counts are continuing to improve, so at least the hairy burden is currently low enough so as not to significantly impair my marrow function.  My WBC is at 4.03, my neutrophils are at 2.6 and my platelets are at 141 -- an all time high since treatment.  I'm still hopeful that I might be able to get another Rituxan treatment while the overall burden and clump sizes are low.

I've read some interesting articles on leukemia using fat as fuel as well as fatty acid involvement in hairy cell membrane morphology.  A study demonstrated how drugs that inhibit fatty acid oxidation may sensitize leukemic cells to drugs that induce apoptosis.   I'm very interested in finding out whether there is a relationship between fatty acid oxidation, body mass index (BMI) and the effectivity of Cladribine.  If one could show that people with lower BMI respond better to Cladribine chemotherapy, then perhaps general approaches to reducing BMI prior to treatment with 2CDA could result in better outcomes for all patients.  My crazy brain at work.  (Afternote:  Turns out there is a basis for my query regarding a correlation between BMI and chemotherapy, although it's not directly related to HCL.  A study of childhood leukemia patients showed that patients with high BMIs were less likely to respond to chemotherapy.  While the theory reported is that cancer cells sequester in body fat, I have my feelings that cellular membrane factors may be involved as well.)

Time to go exercise...

(More random thoughts, 9/9/10) I've been reading about cellular plasma membrane structures called "lipid rafts."  Although these structures are readily observed in cultured cells, they have not been observed in live cells, and their existence in live cells is considered controversial; however, I wonder if hairy cell filopodia (aka villi -- the fine hair-like projections of hairy cells) are actually extrusions of cytoplasmic material from lipid rafts which have large cholesterol concentrations (remember -- hairy cells have high cholesterol content).  I read an abstract from a study entitled "Lipid Raft Disruption Prevents Apoptosis Induced by Cladribine."  It indicates that although leukemic test cells completely absorb Cladribine, disrupting the lipid rafts inhibited the flow of calcium ions through the plasma membrane and reduced the apoptotic effects of Cladribine.  Although the study used ALL cells, I wonder if this is a reason why Cladribine doesn't work well for some HCL patients (the lipid rafts are disrupted or vary in some way that prevents proper biochemical flow to induce apoptosis).  Still, the study probably used cultured cells, so it's hard to know if it applies to live cells.  I'd like to get the full article and learn more about the causes of lipid raft disruption to find out if there are things that can be done to make Cladribine more effective for all patients.  Who knows, maybe this is a factor in HCL-V, and figuring out a way to open the ion pathways will make Cladribine effective in that variant of the disease too.

Similarly, treatment with interferon-alpha has been shown to reduce HCL cholesterol content and villi length.  This would support my theory since lipid rafts are assumed to contain large amounts of cholesterol.  Reducing the cholesterol content of the lipid raft would reduce its area and correspondingly, the amount of material extruded to form the villi would be reduced -- resulting in shorter villi.  I don't know why I write this stuff.  Aside from the fact that I'm desperate to kill these hairy bastards, I suppose I'm hoping a grad student will take it on as a project or at least comment on its plausibility.

(Even more random thoughts, 9/10/2010)  This is kind of cool.  I just found an abstract for a study entitled "Microvilli structures on B lymphocytes: inducible functional domains", which states:  "We also discovered that depletion of cholesterol, using b-methyl-cyclodextrin, lowered the number of microvilli, indicating that intact lipid rafts are required for their expression."  This applies to the microvilli of normal cells, but it is in keeping with my hypothesis regarding unusually large lipid rafts as the source of the filopodia (aka villi of hairy cells.  Perhaps my hypothesis is right.  Now if only I could win the lottery and fund my own studies...

Interestingly enough, there is a patent for a formulation of Cladribine that uses b-cyclodextrin as the soluble agent in lieu of the original benzyl alcohol and propylene glycol cosolvent soluble agent combination.  This is a similar compound as that referred to in the paragraph above (Both β-cyclodextrin and Methyl-β-cyclodextrin (MβCD) remove cholesterol from cultured cells) and it's used to deplete cholesterol and reduce the number of microvilli on B lymphocytes.  If hairy cell villi are indicative of lipid rafts, and lipid rafts are necessary to allow ion flow and induce apoptosis, then perhaps this formulation of Cladribine is slightly less effective than the original version.  I'd like to know which version of the drug I was given.  If b-methyl-cyclodextrin acts as a lipid raft disrupter, then maybe the original formulation is more effective in patients with variant lipid raft function.

(9/11/2010)  I found another great article:  "CD20-mediated apoptosis: signalling through lipid rafts," which seems to imply that in order for Rituxan to induce apoptosis, it must cross-link CD20 proteins that are located in separate lipid rafts.  My initial thought was "does this mean that if your cells have fewer rafts or if the rafts are too large, the drug will be less effective?" and this thought turned out to be mirrored in the final thoughts of the study report: "Finally, it will be important to test the prediction that the size or abundance of lipid rafts in B-cell membranes is a contributing factor to the susceptibility or resistance of patients to CD20-mediated B-cell depletion."  This study's findings resonate a common theme with the other studies I've referenced regarding the involvement of lipid rafts in apoptosis.

Much of this report seems to read as if the high cholesterol content of the cells is necessary in order to allow the calcium ion flow needed for apoptosis to work properly.  This would indicate that going on a low-cholesterol diet during therapy to try to starve the hairies may be counter-productive.  Since the underlying apoptotic biochemical process seems to be the same for Cladribine induced apoptosis as it is for anti-CD20 induced apoptosis, maybe cholesterol gets synthesized into other chemicals during apoptosis -- causing the hairies to suck in more cholesterol from the peripheral blood as they try to survive.  Maybe this explains why my blood cholesterol dropped precipitously during Cladribine chemotherapy (HDL went from 30 to 18 in a matter of days, LDL went from 90s to  high 60s).  I'm guessing that partial apoptosis biochemical processes started and consumed cholesterol, but the calcium mobilization was inhibited so as the cells survived, they consumed more cholesterol from my peripheral blood to reconstitute themselves.  Ultimately, many of them died after six months (went from 80% bone marrow infiltration at 1 month post chemo to 30% at 6 months) probably due to DNA damage and slow but sure calcium mobilization, but too many survived.

I found another article which reinforces and provides further detail on the involvement of cholesterol in B-cell apoptosis: "Cholesterol depletion inhibits src family kinase-dependent calcium mobilization and apoptosis induced by Rituximab crosslinking."

Hmmm....does this mean I should eat Ben and Jerry's Vanilla ice cream during therapy?  Of course not, fat and cholesterol are different substances.  Maybe shrimp is a good compromise -- low in fat, but high in cholesterol.  Leukemia is so paradoxical to the conventional mindset.  This is interesting because studies in many solid tumors (like prostate cancer) show that cholesterol depletion aids in apoptosis.  The differences between leukemia and solid tumors are fascinating.  Time to go watch Woody Allen's "Sleeper" -- turns out chocolate cake is good for you after all...

(9/18/2010)  I got a great reply from the "Hairy Cell Consortium" regarding some questions I had regarding lipid raft research for HCL:

My e-mail to them read as follows:
      Given the findings of the following studies:
          "CD20-mediated apoptosis: signalling through lipid rafts"
          http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1782791/pdf/imm0107-0176.pdf

          and

         "Lipid raft disruption prevents apoptosis induced by Cladribine"
          http://www.ncbi.nlm.nih.gov/pubmed/16730061

          isn't it possible that lipid raft disruption may play a
          significant role in why these drugs
          are are not effective for some patients?
          Why isn't there more research to characterize
          HCL lipid rafts and determine the role that lipid
          rafts have in the disease?

Here's their reply:
 
         Dear Mr. Howard:

        
         The question that you pose about the potential
         importance of "lipid rafts" and response to therapy
         in hairy cell leukemia is excellent. To our knowledge,
         the characterization of "lipid rafts" in hairy cell
         leukemia has not been published. In contrast, lipid
         rafts have been explored in chronic lymphocytic leukemia
         by several investigators. The presence of lipid rafts has
         been correlated with response to cladribine as well
         as response to monoclonal antibodies in vitro. The
         monoclonal antibodies that have been studied include
         both Rituximab and Alemtuzumab. Since both of these
         agents may have some benefit in this disease, all patients
         have not responded. It would be interesting to
         correlate the responsiveness to these agents as well
         as to the purine nucleoside analogues. This is the type
         of study that might be conducted within the Hairy Cell
         Leukemia Consortium. Your question has merit
         because it might provide predictive biomarkers to
         determine who will and will not respond to these agents.

       Regards,
       The HCL Consortium Team

This response made me very happy.  Hopefully, they'll perform some studies.  Who knows, maybe the research will not only provide predictive biomarkers but ways to tailor the structure of antibodies to conform to variances in lipid raft size and placement that fall outside the range accomodated by the current antibodies' structures.