GIST

Question 1

GIST presentation

Answer 1

• asymptomatic
• GI symptoms (early satiety, etc)
• GI bleeds

Question 2

GIST stains

Answer 2

CD117, CD34, DOG1

Question 3

C-KIT exons in GIST

Answer 3

9,11,
less commonly 13 or 17

Question 4

1) Most common sites of metastatic spread in GIST 2) rare site of metastasis

Answer 4

1) liver
peritoneum
2) nodal mets (sarcomas don’t metastasize through lymphatic system)

Question 5

Mutation that requires higher dosing of imatinib

Answer 5

Kit exon 9

Question 6

second line for GIST

Answer 6

• cytoreductive surgery
• Ongoing trial to clarify below:
  *Selection of below also depends on mutational profile
  Sunitinib (Low response rates but delays progression)
  *Requires continuous dosing due to problem of disease rapidly rebounding after holding treatment
  repritinib (equivalent PFS but less toxic)

Question 7

Third line for GIST and preferred option

Answer 7

Regorafenib (Preferred – but difficult to tolerate)
*Repritinib also an option if you can get insurance authorization so Hemming prefers over regorafenib
Nilotinib
Sorafenib

Question 8

Drug targeting PDGFRA

Answer 8

avapritinib

Question 9

High risk features in GIST warranting adjuvant therapy

Answer 9

*10/10/5/5 rule
1) Tumor size >10cm, mitotic rate >10 per 50 HPF, or tumor size >5cm and mitotic count >5
2) also rupture
3) also nongastric location

Question 10

Duration of adjuvant imatinib

Answer 10

5 years

Question 11

General management of localized disease

Answer 11

Upfront surgery if resectable disease w/ adjuvant TKI depending on risk factors