APPENDICURE

If you’re doing ctDNA testing to monitor for recurrence, you likely do not have all of your data.

There is something called a VCF file, which stands for “Variant Call Format”, that most patients are never given unless they specifically request it.

What is a VCF file

It is the underlying data behind your report. It is essentially the full list of mutations found in your tumor.

It includes:
– Every mutation detected
– Where it is in your DNA
– What changed
– How confident the test is
– Variant allele frequency, which tells you how much of the tumor carries it

Think of it like the spreadsheet behind the report, but much more detailed and machine readable.

Why this matters

Your standard report is a summary.

The VCF gives you:
– Exact DNA changes
– Precise genomic location
– Protein level impact
– Data that can actually be analyzed and reused

This is what allows deeper analysis, including neoantigen prediction.

What is a neoantigen

A neoantigen is a new piece of protein created by a tumor mutation that your body has never seen before.

These come directly from mutations in your tumor.

They matter because they are tumor specific and can potentially be recognized by the immune system.

Why HLA matters

Your immune system only sees these neoantigens if they bind to something called HLA. These are molecules that present peptides to T cells.

So neoantigen prediction is the combination of a mutation and HLA compatibility.

Even if a mutation creates a new protein, if it does not bind your HLA, the immune system will never see it.

Reality check

Neoantigen prediction does not guarantee an immune response. It is a probability ranking. It works best when mutations are strong, like frameshift or splice mutations, when the tumor actually expresses the gene and when HLA binding is strong.

How to get your VCF file

I had to request mine from Natera. They do not send it automatically. If you are using the Signatera test from Natera I’ve attached the consent form.

• Fill out their data request form
• In section B, write “Filtered Tumor VCF File”
• Include the date of your original tumor test
• Email it to ecoffman@natera.com

You can print it, fill it out in about a minute, take pictures of the pages and email it back.

If you are using another provider, please reach out to support and request your VCF files. It’s your data – you have a right to it.

Why they do not give this to you upfront

Most clinicians do not use VCF files.

These tests are designed for oncologists and clinical decision making, not for raw data analysis.

A VCF file can contain thousands of data points and requires specialized tools to interpret.

Why this is important

When this data is in the right hands, it can go far beyond a standard report.

It opens the door to a deeper understanding of your tumor, research opportunities, and personalized immunotherapy exploration.

Final thought

If you or someone you love are going through Appendix Cancer, you deserve access to your full data.

Even if you do not use it today, you may want it tomorrow.