Timothy Grass Pollen Allergen Extract (Grastek) (PDF)

Coverage Summary

Timothy Grass Pollen Allergen Extract (Grastek) is covered with criteria per policy CP.PMN.84. The policy defines medical necessity for Grastek as sublingual immunotherapy for grass pollen–induced allergic rhinitis with or without conjunctivitis in patients aged 5–65 years, requires confirmed sensitization to Timothy grass or cross-reactive grasses, limits dosing to ≤ 1 tablet per day, and specifies initial and continued approval requirements and durations for Commercial, HIM, and Medicaid lines of business.

Initial Approval Criteria - Allergic Rhinitis

Covered when ALL of the following are met:

ALL of the following

Diagnosis of grass pollen-induced allergic rhinitis
Prescribed by or in consultation with an allergist or immunologist
Age ≥ 5 years and ≤ 65 years≥ 5 years and ≤ 65 years
Confirmation of a positive skin test or in vitro testing for pollen-specific IgE antibodies for Timothy grass pollen or cross-reactive grass pollens (e.g., sweet vernal, orchard, perennial rye, Kentucky blue/June grass, meadow fescue, or redtop)
Failure of one intranasal corticosteroid, unless clinically significant adverse effects are experienced or all are contraindicated
Step therapy bypass for Illinois HIM requests as of 1/1/2026 per IL HB 5395
Failure of one oral antihistamine at up to maximally indicated doses, unless clinically significant adverse effects are experienced or all are contraindicated
Step therapy bypass for Illinois HIM requests as of 1/1/2026 per IL HB 5395
Dose does not exceed 1 tablet per day≤ 1 tablet/day

Initial Approval Criteria - Other diagnoses/indications

If request does not meet above and drug labeling recently changed within 6 months:

ANY of the following

If drug had a recent label change within last 6 months and is on formulary/PDL, refer to no coverage criteria policy for relevant line of business (CP.CPA.190 commercial; HIM.PA.33 marketplace; CP.PMN.255 Medicaid)
If drug had a recent label change within last 6 months and is NOT on formulary/PDL, refer to non-formulary policy for relevant line of business (CP.CPA.190 commercial; HIM.PA.103 marketplace; CP.PMN.16 Medicaid)
If requested use is not listed under section III and criterion 1 above does not apply, refer to off-label use policy for relevant line of business (CP.CPA.09 commercial; HIM.PA.154 marketplace; CP.PMN.53 Medicaid)

Continued Therapy - Allergic Rhinitis

Continued coverage requires ALL of the following:

ALL of the following

Member status
- Currently receiving medication via Centene benefit or member has previously met initial approval criteria
- Member is currently receiving medication and is enrolled in a state and product with continuity of care regulations (refer to state specific addendums CC.PHARM.03A and CC.PHARM.03B)
Member is responding positively to therapy
If request is for a dose increase, new dose does not exceed 1 tablet per day≤ 1 tablet/day

Continued Therapy - Other diagnoses/indications

If continued use does not meet above and drug labeling recently changed within 6 months:

ANY of the following

If drug had a recent label change within last 6 months and is on formulary/PDL, refer to no coverage criteria policy for relevant line of business (CP.CPA.190 commercial; HIM.PA.33 marketplace; CP.PMN.255 Medicaid)
If drug had a recent label change within last 6 months and is NOT on formulary/PDL, refer to non-formulary policy for relevant line of business (CP.CPA.190 commercial; HIM.PA.103 marketplace; CP.PMN.16 Medicaid)
If requested use is not listed under section III and criterion 1 above does not apply, refer to off-label use policy for relevant line of business (CP.CPA.09 commercial; HIM.PA.154 marketplace; CP.PMN.53 Medicaid)

Diagnoses/Indications not authorized

Coverage is NOT authorized for:

ALL of the following

Non-FDA approved indications, unless sufficient documentation of efficacy and safety per off-label use policies (CP.CPA.09 commercial; HIM.PA.154 marketplace; CP.PMN.53 Medicaid) or evidence of coverage documents

Provider Actions & Authorization Requirements

Prior Authorization

Prior authorization for initial and continued therapy

Requests for Grastek require prior authorization review. Providers should submit documentation demonstrating that the member meets initial or continued therapy criteria. Approval durations vary by line of business (Medicaid/HIM = 12 months; Commercial = 12 months or duration of request, whichever is less).

Documentation Required

Submit supporting documentation

Submit supporting clinical documentation such as office chart notes, laboratory results, or other information showing confirmation of positive skin testing or in vitro testing for Timothy grass or cross-reactive grasses and documentation of prior therapy failures (e.g., intranasal corticosteroid and oral antihistamine trials) as required by the approval criteria.

Referenced Policy Cross-References and Codes

Referenced policy cross-referencesmixed

CP.CPA.190	No coverage criteria policy (commercial)
HIM.PA.33	No coverage criteria policy (health insurance marketplace)
CP.PMN.255	No coverage criteria policy (Medicaid)
HIM.PA.103	Non-formulary policy (health insurance marketplace)
CP.PMN.16	Non-formulary policy (Medicaid)
CP.CPA.09	Off-label use policy (commercial)
HIM.PA.154	Off-label use policy (health insurance marketplace)
CP.PMN.53	Off-label use policy (Medicaid)
CC.PHARM.03A	Continuity of care addendum A
CC.PHARM.03B	Continuity of care addendum B

Background & Clinical Evidence

Grastek is indicated as immunotherapy for the treatment of grass pollen–induced allergic rhinitis with or without conjunctivitis in persons aged 5 through 65 years, and requires confirmation by a positive skin test or in vitro testing for pollen-specific IgE antibodies to Timothy grass or cross-reactive grass pollens. Treatment with Grastek is intended as allergen immunotherapy and is not for immediate symptom relief. The recommended dosing is one tablet once daily, and treatment should be initiated at least 12 weeks before the expected onset of the grass pollen season.

Key evidence and guidance sources include the Grastek Prescribing Information (Merck; December 2019, accessed April 18, 2025) and multiple allergy/rhinitis practice parameters and guideline references supporting immunotherapy practice (references and guideline updates from 2008–2020). These guideline citations and the product PI form the basis for the policy's clinical criteria.

Thresholds & Quick Facts

Dose limit≤ 1 tablet/day

Age range≥ 5 years and ≤ 65 years

Recent label change windowwithin the last 6 months

Definitions

BAU: bioequivalent allergy unit — the unit used to express Grastek tablet potency. Grastek tablets are available as 2,800 BAU per tablet.

Revision History

04.21.25addedLatest

3Q 2025 annual review: added step therapy bypass for Illinois HIM per IL HB 5395; references reviewed and updated. (Effective date referenced in log: 04.21.25; P&T Approval Date = 08.25)

09.28.21revised

Revised approval duration for Commercial line of business to 12 months or duration of request, whichever is less (Change noted with dates 09.28.21; P&T Approval Date 02.22).

03.22.21clarified