GIST Specialist for Cheviot Hills, CA
When a gastrointestinal stromal tumor stops responding to a drug that had been working for years, it is usually because the tumor changed rather than the drug failed. That distinction determines what should happen next. Joshua Ellenhorn, MD, FACS assesses when surgery is part of the answer.
- Surgical assessment for focal progression on targeted therapy
- Clinical Professor of Surgery, Cedars-Sinai Medical Center
- Resection and ablation of resistant deposits
- Works alongside your medical oncologist rather than replacing them
The Tumor Changes, Not the Drug
Nearly all gastrointestinal stromal tumors are driven by a mutation in KIT or PDGFRA that jams a growth signal permanently on. Imatinib works by blocking that signal, and in responsive tumors it works remarkably well, often for years.
What ends that period is generally not the drug wearing out. It is the tumor acquiring a second mutation, elsewhere in the same gene, which changes the shape of the target enough that the drug no longer binds effectively. The original mutation is still there. A new one has appeared alongside it under the selective pressure of treatment.
This explains something patients often find puzzling, which is why the later drugs typically work for shorter periods than imatinib did. They are not weaker. They were developed against particular resistance mutations, and the difficulty is that different metastatic deposits in the same patient can acquire different ones. A drug that neutralises the resistant clone in the liver may do nothing for the one on the peritoneum. That heterogeneity, rather than any deficiency in the medication, is what limits how long each successive line holds.
It also explains where surgery fits. If a single deposit is growing while everything else stays controlled, that deposit is where the resistant clone lives. Removing it can extend the useful life of a drug that is still working perfectly well everywhere else.
Why There Is an Order to the Drugs
Each agent was developed against a different problem. This is the logic behind the sequence rather than a ranking by strength.
| Agent | Where it sits | What it was built for |
|---|---|---|
| Imatinib | First line | The original KIT and PDGFRA mutations. Highly effective in responsive tumors, and still the best starting point for them |
| Sunitinib | Second line | Particularly certain secondary mutations in the region that acts as a gatekeeper to the drug binding site |
| Regorafenib | Third line | A different set of secondary mutations, in the activation loop of the receptor |
| Ripretinib | Fourth line | Designed to work across a broad range of resistance mutations rather than one specific pattern |
| Avapritinib | Specific indication | PDGFRA D842V tumors, which never respond to imatinib at all. Primary rather than secondary resistance |
| Clinical trials | Any point | Particularly relevant once established options are exhausted, or for wild type and SDH-deficient disease |
Drug selection and monitoring belong with your medical oncologist. What is assessed here is whether an operation would add anything at a given point in that sequence.
Never Worked, or Stopped Working
The distinction between primary and secondary resistance changes everything about what should happen next, and it is worth being clear which one applies to you.
Primary resistance means the tumor never responded. The usual causes are a PDGFRA D842V mutation, wild type status where no KIT or PDGFRA mutation is found, or SDH deficiency. These are recognisable from the outset if mutation testing is done, which is the strongest argument for doing it before starting treatment rather than after. Months spent on a drug that was never going to work are months that cannot be recovered.
Secondary resistance means the tumor responded, sometimes for years, and then a new mutation emerged. This is a different and considerably better situation, because there is a defined sequence of later agents and, where progression is focal, a surgical option as well.
Both are worth distinguishing from a third possibility, which is that the tumor is not actually progressing at all. A responding GIST can appear larger on imaging because of bleeding or fluid change within it, and previously invisible liver deposits can become visible as they respond. Confirming that apparent progression is real comes before acting on it.
Three Situations, Three Answers
The pattern of progression, not its presence, determines whether an operation is useful.
Resect the Resistant Clone
One deposit growing while the rest stay controlled. Removing or ablating it can extend the useful life of the current drug, which is worth more than moving to the next line prematurely.
Change the Drug
Everything growing together means the resistance is widespread and surgery cannot address it. The answer is the next agent in the sequence, chosen where possible on the resistance pattern.
Consider Consolidation
Stable or responding for a year or more with limited residual disease. Resecting what remains may consolidate the gain, and this reassessment frequently never happens because nobody thinks to ask.
The Surgery Behind the Strategy
Recordings of real GIST resections narrated by the surgeon who performed them. Operating on treated, resistant disease requires the same discipline these show.
Laparoscopic Resection of a Gastric GIST
A gastric GIST removed through small incisions with the capsule kept intact.
Gastric GIST Resection: A Simplified Approach
A refined approach that shortens operating time and recovery.
Robotic Resection of a Duodenal GIST
Duodenal GIST removed robotically with the pancreas and bile duct preserved.
Ask Whether It Can Be Removed
Focal progression on an otherwise effective drug is the clearest surgical opportunity in advanced GIST, and it is frequently treated as a reason to switch agents instead. Both options should at least be on the table.
Certifications and Appointments
Two American Board of Surgery certifications, a Cedars-Sinai teaching appointment, and membership of the societies that publish the treatment sequence described above.
- American Board of Surgery, certified in General Surgery
- American Board of Surgery, certified in Colorectal Surgery
- California State Medical License
- Florida State Medical License
Joshua Ellenhorn, MD, FACS
Dr. Ellenhorn is a surgical oncologist and Clinical Professor of Surgery at Cedars-Sinai Medical Center, and a collaborative member of the Samuel Oschin Comprehensive Cancer Institute.
Understanding drug resistance is not conventionally a surgeon concern, and that is precisely the gap this page describes. The surgical opportunity in advanced GIST is narrow and specific: a single progressing deposit on an otherwise effective regimen. Recognising it requires following the imaging and the mutation data closely enough to distinguish focal progression from generalised progression, and from apparent progression that is not real at all. A surgeon who waits to be asked will miss the window.
He is certified by the American Board of Surgery in General Surgery and in Colorectal Surgery, a Fellow of the American College of Surgeons, and a member of the Society of Surgical Oncology and the American Society of Clinical Oncology. He practises with the Surgery Group of Los Angeles.
Questions About Progression
Take these to whoever manages your medication. Most are answerable from imaging and pathology you already have.
- Is my resistance primary or secondary?
- What was my original mutation subtype?
- Is the progression focal or generalised?
- Has apparent growth been confirmed as real rather than fluid or bleeding change?
- Would a repeat biopsy or ctDNA test guide the next drug choice?
- Which agent comes next, and why that one?
- Could the progressing deposit be resected or ablated instead?
- Is there a clinical trial appropriate for my resistance pattern?
What Patients Say
Reviews left by patients treated by Dr. Ellenhorn at the Surgery Group of Los Angeles.
★★★★★The staff at the Surgery Group of Los Angeles are wonderful. They are kind, very attentive, the office is clean and I did not have to wait long at all. I cannot say enough great things about Dr. Ellenhorn. He is an excellent surgeon who is highly skilled and very knowledgeable. I cannot thank him enough for all he has done for my family and I.
Erika Frank
★★★★★Very kind stuff, great service. Dr Joshua Ellenhorn is a very calm doctor who takes time with his patient.
Anita Lukacevic
From Cheviot Hills
Motor Avenue or Overland north to Pico, east, then north on Robertson or La Cienega to 3rd Street. Fifteen to twenty minutes in ordinary conditions. From the Rancho Park side, Westwood Boulevard north to Pico is equally straightforward.
The office is in the medical plaza attached to Cedars-Sinai Medical Center. For patients on long term targeted therapy, having imaging, medical oncology and the surgical practice in one institution is what makes the reassessment described on this page happen at all, rather than depending on a report being forwarded between offices.
Patients travelling from outside the region, including Arizona and Nevada, can have imaging and pathology reviewed remotely.
8635 W 3rd St, Suite 880W
Los Angeles, CA 90048
Monday to Saturday, 11:00am to 8:00pm
Closed Sunday
Frequently Asked Questions
Why does imatinib eventually stop working?
What is the difference between primary and secondary resistance?
Why not just use the strongest drug first?
Why do the later drugs work for shorter periods?
Can a blood test detect resistance?
Where does surgery fit into resistance?
Should the tumor be biopsied again at progression?
How far is your office from Cheviot Hills?
One Spot Growing Is Not the Same as Progression.
If a single deposit is advancing while the rest of your disease stays controlled, removing it may extend the drug you are on. That assessment is worth asking for explicitly.
