Monday, May 25, 2015

Tumor Progression

It has finally happened to me - the dreaded news of cancer progression.  After 4+ years on Sandostatin LAR and debulking surgery my remaining tumors have started to grow and progress.  The good news is there are no new visible tumors. Things were stable until this March when my MRI showed tumor progression in my liver and one of my lymph nodes.  We increased my dose of Sandostatin LAR from 20 mg to 30 mg in March, hoping that might slow down any further progression.  My doctor wants to do another MRI in July to see if the tumors are still progressing.  In July, if the tumors are stable we’ll just continue with the 30 mg Sandostatin LAR. Since there are no approved drugs for mid-gut NET patients that have progressed on Sandostatin LAR, My doctor mentioned some clinical trials that I might be well suited for that are going on at Dana Farber as follows:

1)  Immunotherapy Phase 1B trial of MK-3475 in patients with advanced solid tumors

2)  Angiogenesis inhibitors (new form of chemotherapy) – there are a few choices for me in this category

The immunotherapy trial originally sounded interesting.  MK-3475 is the immunotherapy drug that has been used in advanced melanoma patients that has put some of them into remission.  It works by targeting a protein called PD-L1 that allows the cancer cells to live and multiply without disturbance from the immune system.  MK-3475 is a drug that blocks the PD-L1 protein so that your own immune system can attack the tumor.  Basically, if my tumor tested positive for PD-L1 then I would be eligible to try this clinical trial to see if the drug would work for my NETs. 

Unfortunately, my tumor test was not positive and from what I understand, none of the NET tumor samples tested positive.  I guess it means that this particular pathway to immunotherapy does not work for NETs and from what I’ve heard, most other gastrointestinal cancers.  So if the tumors progress further, it’s on to angiogenesis inhibitors for me.

Angiogenesis inhibitors have dissimilar side effects from most conventional chemotherapy medications because they work very differently. Rather than killing healthy cells along with cancer cells, as many chemotherapy drugs do, angiogenesis inhibitors only prevent new blood vessels from forming. 

At this point, there are no FDA approved angiogenesis inhibitors for mid-gut NETS.  For pancreatic NETs, Sunitinib (Sutent) and Everolmus (Afinitor) are approved.  The clinical trials that my doctor presented to me are for two drugs as follows:

1)  Cabozantinib:  This is a phase 2 trial of a drug that is approved for thyroid cancer. 

2)  Aflibercept:  This is also a phase 2 trial of a drug that is approved for colorectal cancer.  

Both these drugs, like all cancer drugs, have multiple side effects associated with them.  All things being equal (and I don’t know if they are), I’d take the Cabozantinib because it is available in pill form rather than infusion.  Neither of these clinical trials is randomized, meaning that there is no placebo arm so if I do one of them, I will definitely be getting the real drug.

My issue with angiogenesis inhibitors is that they seem to work better for pancreatic NETs than for mid-gut NETs.  My feeling is based on some articles I have read and the fact that they are only FDA approved for pancreatic NETs.  My doctor generally agrees with me but believes that the inhibitors may still work for mid-guts, just not as well as they do for pancreatic NETs.  

She also suggested taking Afinitor on an off label basis, meaning that it is not approved for my specific condition.  If I took Afinitor, at least I would not be subject to the rigorous rules of a clinical trial.  Novartis released information last week about a phase III trial called Radiant-4 that showed that Afinitor met the trial goals for gastrointestinal and lung NETs. This study might be enough for the FDA to approve Afinitor for other NET types than pancreatic.

I asked her if we should consider peptide receptor radionuclide therapy (PRRT). She said that this could be a possibility at a later stage.  She also doesn't think any liver specific treatment makes sense at this point since I have low liver involvement and tumors outside my liver. At this point my tumor load is light and I don’t have too much carcinoid syndrome. The angiogenesis inhibitors make sense to see if that helps slow progression. 

I went to a patient conference where Dr. O’Dorisio at the University of Iowa passed out a treatment chart that showed the different treatments available for NETs and their average time to progression (TTP).  If one looks at the treatment chart, the angiogenesis inhibitors have an average time to progression of 7 months.  That seems like a pretty short time to me but I know the TTP can be much longer for some patients.  My doctor thinks that there may be additional PRRT trials available in the US in the next year if necessary for my case.  It may make sense to partake in that treatment.  I could also go to Europe for PRRT where they are much farther along in the development of this therapy.  I have some time to think about this as I wait for my disease to progress.  Hopefully the progression will be slow.

The link to Dr. O’Dorisio’s chart is below: