One of the big debates among those who treat cancer metastasis to the brain is what drugs can cross the tight blood-brain barrier and penetrate the brain enough to kill tumors. It has been widely accepted that chemo and targeted therapy made of small molecules can cross into the brain, but those made of large molecules can’t.
Since I had a craniotomy 2.5 years ago to remove two 3cm tumors from the right side of my brain, I have dealt with persistent regrowth in the tumor bed. The tumor bed was radiated and I was put on two small-molecule drugs. The tumor bed was stable for awhile and then small changes started to be seen on my MRIs. The radiologists/oncologists didn’t know if we were looking at tumor progression, radiation necrosis or blood byproducts. So we watched and waited.
Over the fall and winter, I had been on a large-molecule chemo/targeted therapy combo that had kept my small liver mets stable but not regressing. At the end of January, a liver lesion grew 5mm. That often isn’t enough growth to switch treatment, but since I was interested in clinical trials and the current treatment wasn’t shrinking anything, we decided to change right then. I started exploring a clinical trial of an Anti-Body Drug Conjugate that was only in Phase 1 studies but had been performing well so far.
Among my list of tests I had to get done before beginning this trial was a brain MRI since the trial would only accept me if I had stable brain mets. The MRI was performed, there was some miscommunication, I was told that it was stable, I was enrolled into the trial based on the assumption that it was stable, however it was very much NOT stable. I found out later that the most persistent tumor had regrown to 6cm at the longest point (from what I could decipher from reports, it was a long, skinny tumor snaking along the side of my brain). Then, the second tumor bed regrowth had grown to almost it’s original size of 3cm.
Thankfully, this growth was somehow missed and I started the trial anyway. After about four months on the trial, I finally had a follow-up brain MRI. The results were phenomenal. The biggest, stubbornest tumor was less than 3cm and the second residual tumor had shrunk down to 4mm.
So based on my results, my oncologist is actually talking about trying to open up an arm of this trial specifically for people with brain mets. As those with brain mets are often excluded from trials, this could be a breakthrough. Also, the linked drug in this ADC is a topoisomerase inhibitor and topotecan, another topoisomerase inhibitor has had some success treating lepto mets, which is a devastating but growing problem. Us with brain mets need the breakthroughs that may come of this.
Science is cool. And I love being part of it.