CODING & BILLING
KEYTRUDA QLEX FOR ADVANCED MSI-H/dMMR COLORECTAL CANCER
This resource contains information for selected indications for KEYTRUDA QLEX. It is provided as a reference only and may be relevant when billing for KEYTRUDA QLEX, and the administration of this product. This information is current as of February 2026. For information about billing and coding products other than KEYTRUDA QLEX, please contact the manufacturer of the product or the applicable payer.
When submitting a claim for KEYTRUDA QLEX, always verify coding requirements with the relevant payer. Coding requirements may vary by insurer or plan; please refer to the payer-specific policies to understand what may be covered.
Check with the relevant payer regarding guidance on which diagnoses they will recognize and the applicability of secondary codes. Health care professionals are solely responsible for selecting codes that appropriately reflect the patient’s diagnosis, the services rendered, and the applicable payers’ guidelines.
Providers should document the diagnosis with a sufficiently high degree of specificity based on the information available to enable the identification of the most appropriate code. Although CMS has said that an unspecified code may be appropriate in some cases, CMS has advised that you should always code with as much specificity as possible to be consistent with the clinical documentation.
Merck and its agents make no warranties concerning the accuracy or appropriateness of this information for your particular use given the frequent changes in public and private payer billing. Merck cautions that payer-coding requirements vary and can frequently change, so it is important to regularly check with each payer or, where applicable, the Medicare Administrative Contractor as to payer-specific requirements. The use of this information does not guarantee payment or that any payment received will cover your costs.
Indication
KEYTRUDA QLEX is indicated for the treatment of adult patients with unresectable or metastatic microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) colorectal cancer (CRC) as determined by an FDA-authorized test.
CMS=Centers for Medicare & Medicaid Services.
Click here for FDA-approved dosing information.
Possible relevant diagnosis codes for advanced MSI-H/dMMR CRC
Learn more about each diagnosis code and descriptor by selecting from the series options below.
When assigning ICD-10-CM for MSI-H/dMMR advanced tumors treated with KEYTRUDA, identify the appropriate ICD-10-CM category for the advanced malignant neoplasm of the body part under treatment and select the code based on the specific site. For example: C18.6 malignant neoplasm of descending colon.