KIT D816V

aka KIT D816V, D816V, c-KIT D816V, KIT exon 17 mutation, KIT D816V mastocytosis

KIT D816V is the mutation behind almost every case of systemic mastocytosis. It makes the disease resistant to imatinib, and it is detected by a highly sensitive blood PCR; avapritinib treats the disease whether or not the mutation is confirmed.

The exon 17 D816V substitution locks KIT in the active conformation and is present in over 90 percent of systemic mastocytosis, often at low allele burden requiring sensitive allele-specific PCR of blood or marrow. The FDA companion diagnostic list carries the ARUP KIT D816V Assay for imatinib in aggressive systemic mastocytosis (a humanitarian device exemption, H140006, 2015): imatinib is labelled for aggressive systemic mastocytosis without the D816V mutation or with unknown status, so the test selects patients by excluding D816V. Avapritinib's labels for advanced and indolent systemic mastocytosis do not require D816V testing; the mutation is also found in core-binding-factor AML and some GISTs where it confers imatinib resistance.

Part ofKIT· KIT All readouts

KIT: what it is and how drugs act on it · animated schematic, not to scale

Target · the protein and the cell it sits on
Drug · antibody, small molecule, cell or radioligand
Effect · signal, damage or kill

In plain words · KIT mutation is the driver behind most gastrointestinal stromal tumours, and the reason imatinib turned a sarcoma with a median survival of about a year into a chronic disease.

Sequencing 1 approval threshold

What it means for a patient

In systemic mastocytosis a KIT D816V result confirms the diagnosis and tells your team that imatinib will not work; avapritinib is the on-label targeted treatment and does not require the mutation to be shown. The mutation is often present in tiny amounts, so a negative result from an insensitive test should be repeated with a sensitive blood PCR.

Written only from the label or guideline text cited on this page. Not medical advice; your own report and the reading your team gives it come first.

Scoring rule

The KIT c.2447A>T (p.D816V) substitution by allele-specific quantitative PCR or sequencing of blood or marrow; for imatinib the selecting result is its absence.

“KIT D816V Assay (ARUP Laboratories, Inc.): KIT D816V”
FDA: List of FDA-Authorized Companion Diagnostic Devices

Thresholds used in approvals

Threshold	Drug	Cancer	Regulator	Source
D816V absent or unknown (negative selector for imatinib) Imatinib's label covers aggressive systemic mastocytosis without the D816V c-Kit mutation or with unknown mutational status.	Imatinib	Systemic mastocytosis	FDA	label

Drugs whose label names it

Imatinib

Companion diagnostics (FDA list)

Device	Maker	Indication and sample	Drug	PMA / 510(k)
KIT D816V Assay	ARUP Laboratories	Aggressive Systemic Mastocytosis - Bone Marrow	Imatinib	H140006 (12/18/2015)

Tests that measure it

FoundationOne Heme NeoGenomics NeoTYPE profiles

Trials that name this readout

Matched on the name and aliases of the readout in the title, setting and summary of each trial; a match is a mention, not proof the readout was an entry criterion.