Phesgo (pertuzumab + trastuzumab + hyaluronidase-zzxf) — HCPCS J9316

About Phesgo FDA verified May 2026

Genentech's subcutaneous fixed-dose combination of pertuzumab + trastuzumab. One injection, 5–8 minutes, replaces ~150 minutes of combined IV chair time.

Phesgo (pertuzumab, trastuzumab, and hyaluronidase-zzxf injection) is a fixed-dose subcutaneous combination product approved by the FDA on June 29, 2020 (BLA 761170) for adult patients with HER2-positive breast cancer. It bundles three components into one SC injection: pertuzumab (HER2 dimerization inhibitor, the active ingredient in IV Perjeta), trastuzumab (HER2 antibody, the active ingredient in IV Herceptin), and hyaluronidase-zzxf (recombinant human hyaluronidase that transiently degrades subcutaneous hyaluronic acid, enabling rapid SC delivery of a high-volume biologic).

Phesgo replaces the IV Perjeta + Herceptin combination with a single SC injection administered over 5–8 minutes (vs the ~150 minutes of combined chair time across two sequential IV infusions). It is manufactured by Genentech (a Roche subsidiary), with the same approved indications as IV Perjeta + Herceptin: HER2+ metastatic breast cancer (in combination with docetaxel as first-line); HER2+ early breast cancer in the neoadjuvant setting (in combination with chemotherapy); and HER2+ early breast cancer in the adjuvant setting (as part of a complete year of HER2-targeted therapy).

The FDA approval was supported by the FeDeriCa Phase III non-inferiority trial, which established pharmacokinetic non-inferiority of SC Phesgo to IV Perjeta + Herceptin (primary endpoint: cycle 7 pre-dose serum pertuzumab Ctrough), with comparable efficacy (pathologic complete response) and a similar cardiac safety profile. The PRESTIGIO real-world evidence program continues to inform post-approval data on site-of-care economics and patient preference for SC vs IV delivery.

Billing-side relevance: Phesgo uses HCPCS J9316 — a single combination J-code permanent effective July 1, 2021 — with a 10 mg-pertuzumab unit basis distinct from the IV components (J9306 Perjeta = 1 mg/unit; J9355 Herceptin = 10 mg/unit). The HCPCS short descriptor is "Pertuzu, trastuzu, 10 mg." Misclassifying Phesgo as split IV components (or coding J9316 with the wrong unit basis) are the two dominant denial patterns for this drug.

Phesgo SC vs. Perjeta IV + Herceptin IV FDA verified May 2026

Same active ingredients (pertuzumab + trastuzumab), three very different billing pathways: J9316 single combo vs J9306 + J9355 split components.

Genentech offers HER2-targeted dual blockade in two product formats: the original two intravenous infusions (Perjeta J9306 + Herceptin J9355, since 2012/1998) and the fixed-dose subcutaneous combination Phesgo (J9316, since 2020). Despite identical active ingredients (pertuzumab + trastuzumab), they are separate BLAs with separate NDCs, separate administration codes, and separate reimbursement math.

Dosing & unit math FDA label verified May 2026

Phesgo is fixed-dose — NOT weight-based. Same dosing for every adult patient regardless of body weight or BSA.

Adult dosing — HER2+ metastatic and early breast cancer (all indications)

• Loading dose (cycle 1): 1,200 mg pertuzumab + 600 mg trastuzumab + 30,000 units hyaluronidase-zzxf, supplied as a 15 mL vial; ~8 mL injected SC into the thigh over 8 minutes — bill 120 units of J9316 (uses 1 loading kit, NDC 50242-251-01)
• Maintenance dose (cycles 2+): 600 mg pertuzumab + 600 mg trastuzumab + 20,000 units hyaluronidase-zzxf, supplied as a 10 mL vial; ~5 mL injected SC into the thigh over 5 minutes every 3 weeks — bill 60 units of J9316 (uses 1 maintenance kit, NDC 50242-250-01)
• Alternate injection thighs each cycle; do NOT mix Phesgo with other products in the same syringe
• Observation: 30 minutes after loading dose; 15 minutes after maintenance doses (infusion-reaction surveillance)
• If a maintenance dose is missed by more than 6 weeks, re-administer the loading dose (120 units) at the next visit, then resume maintenance q3wk

Unit basis — the 10 mg pertuzumab rule

The HCPCS short descriptor for J9316 is "Pertuzu, trastuzu, 10 mg." One billable unit = 10 mg of pertuzumab content (the same unit includes the 600 mg of trastuzumab and the hyaluronidase, all bundled). So the unit math is driven by the pertuzumab dose: 1,200 mg pertuzumab loading ÷ 10 = 120 units; 600 mg pertuzumab maintenance ÷ 10 = 60 units. Do NOT bill J9316 at a 1 mg/unit basis (a frequent error from coders who treat it like J9306) and do NOT bill the trastuzumab content as a separate line (a frequent error from coders who treat it like the IV split).

Pediatric dosing

• Not approved. Phesgo has no pediatric indication.

Combination regimens (per FDA label and NCCN)

• HER2+ metastatic breast cancer (1L): Phesgo + docetaxel — until disease progression or unacceptable toxicity
• HER2+ early breast cancer, neoadjuvant: Phesgo + chemotherapy backbone — cycles before surgery
• HER2+ early breast cancer, adjuvant: Phesgo monotherapy (or with chemotherapy backbone) — total of 1 year of HER2-targeted therapy

Worked example — first-year billing for HER2+ metastatic breast cancer

Premedication

Phesgo does not require routine pre-injection corticosteroid or antihistamine. The chemo backbone (e.g., docetaxel) may carry its own premedication requirements. Manage SC injection-site reactions and any systemic infusion-reaction symptoms per FDA label if they occur during or after the injection.

Cardiac monitoring (LVEF)

Phesgo inherits the cardiotoxicity profile of both IV pertuzumab and IV trastuzumab. Assess LVEF at baseline before initiating Phesgo, then every 3 months during therapy (metastatic) and every 3 months during therapy + every 6 months for 24 months post-completion (early breast adjuvant). Echocardiogram (CPT 93306) or MUGA scan (CPT 78472/78473) is the standard assessment. Withhold for symptomatic LVEF decline or LVEF <40% (or LVEF 40–45% with ≥10 percentage-point absolute decrease from baseline). Many payers will not approve initiation without baseline LVEF documented in the PA.

NDC reference FDA NDC Directory verified May 2026

Administration codes CPT verified May 2026

Single billable SC administration code (96401) for the combo product, regardless of loading vs maintenance dose. Do NOT bill 96417 for the trastuzumab content; Phesgo is one product, not two sequential drugs.

Modifiers CMS verified May 2026

JZ — required on virtually every adult Phesgo claim

Effective July 1, 2023, CMS requires the JZ modifier on all single-dose container claims when no drug is discarded. Phesgo loading and maintenance vials are single-dose, preformulated fixed doses — the entire labeled dose is drawn up and administered, with no partial-vial waste in the standard adult use case. Because Phesgo is a fixed dose (not weight-based), there is essentially never partial-vial waste. JZ applies to virtually every adult Phesgo claim.

JW — rare waste only

JW reports the discarded portion of a single-dose container. For Phesgo, JW would only apply in the rare scenario where a portion is discarded (spoilage during preparation, dose modification mid-prep, dropped vial, etc.). When this occurs, bill JW on a separate claim line with the actual discarded units. One of JZ or JW must be on every J9316 claim.

Worked unit-math example

Modifier 25 — same-day E/M

Use modifier 25 on the E/M code when a significant, separately identifiable evaluation and management service is performed on the same day as the injection (e.g., LVEF result review and dose decision). Routine pre-injection clinical assessment is bundled.

340B modifiers (JG, TB)

For 340B-acquired Phesgo, follow your MAC's current 340B modifier policy. Hospital Outpatient Prospective Payment System (OPPS) hospitals typically append JG (340B-acquired drug) or TB (340B-acquired drug, no payment adjustment) per their MAC instructions.

ICD-10-CM by indication FY2026 verified May 2026

Phesgo is approved exclusively for HER2+ breast cancer (same indications as IV Perjeta + Herceptin). Use the most specific C50.x code supported by encounter documentation, plus laterality and metastatic-site codes as documented.

Site of care & place of service Verified May 2026

Phesgo's 5–8 minute SC injection profile makes it the most office-friendly HER2-targeted regimen on the market. UnitedHealthcare and Aetna have published explicit site-of-care steering favoring SC formulations over IV for maintenance phase. HOPD is generally reserved for the loading dose (with 30-minute observation) and for encounters where chemotherapy is co-administered.

Claim form field mapping Genentech Mar 2026

From Genentech Access Solutions HCP coding & coverage page for Phesgo. A Phesgo claim is one drug line + one admin line + one diagnosis — simpler than the IV split-component pattern.

Payer policy snapshot + HER2 requirements Reviewed May 2026

All major payers cover Phesgo for FDA-approved HER2+ indications with HER2 documentation. Switching from IV requires a new PA; most plans do NOT auto-convert.

Step therapy

Some commercial plans require documented trial of IV Perjeta + Herceptin (or a clinical contraindication to IV) before approving Phesgo. Other plans treat Phesgo as a first-line alternative without step. Verify per-payer step requirements before submitting the PA. For 1L HER2+ MBC and HER2+ early breast cancer (FDA on-label indications), step therapy is generally not required.

Switch documentation (IV → SC)

When switching a patient from IV Perjeta + Herceptin to Phesgo SC, submit a new PA with: (1) HER2 test result; (2) prior IV cycle history; (3) clinical reason for the SC formulation (e.g., chair-time burden, vascular access issues, patient preference, payer site-of-care steering); (4) baseline LVEF (or current LVEF if continuing from IV); (5) ICD-10 + line-of-therapy documentation. Most payers approve switch promptly when all five items are in the submission.

HER2 testing — same criteria as Perjeta + Herceptin IV

• HER2 IHC 3+ (uniform, intense membrane staining of >10% of invasive tumor cells) — HER2-positive without further testing
• HER2 IHC 2+ (equivocal) AND in situ hybridization (FISH/CISH/SISH) confirming amplification:
  • HER2/CEP17 ratio ≥2.0, OR
  • HER2 gene copy number ≥6.0 signals/cell (regardless of ratio)
• HER2 IHC 0 or 1+ — HER2-negative; not eligible for Phesgo
• HER2 test CPTs: 88360 (IHC, manual) / 88361 (IHC, computer-assisted) / 88374 (ISH single probe) / 88377 (ISH multiplex) / 88368 / 88369 (FISH)

Medicare reimbursement CMS Q2 2026 (live)

Quarterly ASP from CMS Part B Drug Pricing File. Refreshes automatically each quarter. Per-dose calculation shown separately for loading and maintenance.

Coverage

No NCD specific to Phesgo. Coverage falls under MAC LCDs for biologics + the generic drug-coverage framework. All MACs cover J9316 for FDA-approved on-label HER2+ breast cancer indications with appropriate ICD-10, HER2 documentation, and (for advanced disease) chemotherapy backbone documentation. Medicare Part B (not Part D); provider buy-and-bill or specialty distribution.

Code history

• J9316 — permanent code, effective July 1, 2021 (FDA approval was June 29, 2020; pre-permanent-code period used unclassified J3490 / J9999)
• HCPCS long descriptor: "Injection, pertuzumab, trastuzumab, and hyaluronidase-zzxf, per 10 mg pertuzumab and 10 mg trastuzumab"
• HCPCS short descriptor: "Pertuzu, trastuzu, 10 mg"
• Cross-reference IV components: J9306 (Perjeta, 1 mg/unit, eff 1/1/2014) and J9355 (Herceptin, 10 mg/unit, eff 1/1/1999) + biosimilars

Patient assistance — Genentech Access Solutions Genentech verified May 2026

• Genentech Access Solutions: 1-866-422-2377 / genentech-access.com — benefits investigation, prior authorization assistance, appeal support, switch-from-IV documentation
• Genentech Oncology Co-pay Assistance Program: commercial copay support up to $25,000/year, $0 out-of-pocket for eligible commercially-insured patients (excludes Medicare, Medicaid, federal program patients, including TRICARE and VA). Eligibility: commercially insured, U.S. resident, age 18+, on-label Phesgo prescription. Income limits not specified; verify at enrollment.
• Genentech Patient Foundation: 1-888-941-3331 — free Phesgo for uninsured / underinsured patients meeting income requirements (generally ≤500% FPL, verify annually). Enrollment: genentech-access.com or fax application from prescriber.
• Foundations (for Medicare/Medicaid patients): PAN Foundation, HealthWell, CancerCare HER2+ breast cancer or general oncology funds — verify open funds quarterly
• Web: genentech-access.com/hcp/brands/phesgo

Common denials & how to fix them

Frequently asked questions

Phesgo vs Perjeta + Herceptin IV — which do I bill?

If the patient received the subcutaneous fixed-dose combination Phesgo, bill a single line of HCPCS J9316 — never bill it as separate Perjeta (J9306) + Herceptin (J9355) IV component lines. J9316 is one combo code that covers pertuzumab + trastuzumab + hyaluronidase-zzxf in the same vial. If the patient received two separate IV infusions (Perjeta then Herceptin), bill J9306 + J9355 on separate drug lines. The SC product and the IV components are distinct BLAs (Phesgo BLA 761170 vs Perjeta BLA 125409 + Herceptin BLA 103792), distinct NDCs, and a distinct billing pathway. Misclassifying Phesgo as split IV components (or vice versa) is the #2 denial cause for J9316.

How many units of J9316 do I bill for loading vs maintenance?

The HCPCS descriptor for J9316 is "Pertuzu, trastuzu, 10 mg" — one billable unit equals 10 mg of pertuzumab content (the same dose includes 600 mg of trastuzumab plus hyaluronidase, all bundled in the single combo unit). Loading dose: 1,200 mg pertuzumab / 600 mg trastuzumab in 15 mL SC = bill 120 units (1,200 ÷ 10). Maintenance dose: 600 mg pertuzumab / 600 mg trastuzumab in 10 mL SC q3 weeks = bill 60 units (600 ÷ 10). Year-1 totals: 1 loading (120 units) + ~16 maintenance (16 × 60 = 960 units) = 1,080 units.

What CPT do I bill for Phesgo administration?

CPT 96401 — "Chemotherapy administration, subcutaneous or intramuscular; non-hormonal anti-neoplastic." This is the single billable administration code for Phesgo regardless of whether you're giving the loading or maintenance dose; the combo is one SC injection over 5–8 minutes (loading) or 5 minutes (maintenance), into the thigh. You do NOT bill 96413 (chemo IV) or 96372 (therapeutic SC) — those are wrong category. You do NOT bill 96417 for the trastuzumab component because Phesgo is a single combination product, not two sequential drugs.

Can patients switch from IV Perjeta + Herceptin to Phesgo SC mid-treatment?

Yes, per the FDA label, patients can switch from IV Perjeta + Herceptin to Phesgo SC at any cycle. The FeDeriCa trial (Phase III non-inferiority study) established pharmacokinetic non-inferiority of Phesgo SC to the IV Perjeta + Herceptin combination, leading to FDA approval on June 29, 2020. Practical billing: when switching, the first Phesgo dose is administered as the Phesgo loading dose (1,200 mg / 600 mg, 120 units of J9316) regardless of the patient's prior IV cycle, then maintenance q3 weeks. Most payers require a new prior authorization for the SC formulation — do NOT assume the original Perjeta + Herceptin PA covers Phesgo.

Is HER2 testing required for Phesgo prior auth?

Yes — Phesgo carries the same HER2 positivity requirement as IV Perjeta + Herceptin. Payer PA requires either HER2 IHC 3+ or HER2 IHC 2+ confirmed by FISH/ISH amplification (HER2/CEP17 ratio ≥2.0 or HER2 gene copy number ≥6.0). All major payers (UHC, Aetna, BCBS) require the HER2 result in the PA submission. Companion-diagnostic documentation missing is the #1 denial cause for J9316. Schedule HER2 testing (CPT 88360 IHC; 88374/88377 ISH; 88368/88369 FISH) before submitting the Phesgo PA.

Why is the J-code different for Phesgo SC vs Perjeta IV + Herceptin IV?

Phesgo is a different BLA (761170, approved June 29, 2020) with different NDCs, different administration route (SC vs IV), different pharmacokinetics enabled by recombinant human hyaluronidase (which transiently degrades subcutaneous hyaluronic acid to allow rapid SC absorption of high-volume biologics), and a different reimbursement pathway. CMS issued J9316 effective July 1, 2021 as a single combination code so the SC combo is billed once rather than as two split components. The 10 mg unit basis matches the combined dosage architecture rather than the legacy per-mg basis of J9306.

Where is Phesgo administered — HOPD, office, or home?

Loading dose (1,200 mg / 600 mg, ~8 mL SC over 8 minutes) is typically administered in HOPD or oncology office with a 30-minute post-injection observation period for infusion reactions. Maintenance doses (600 mg / 600 mg, ~5 mL SC over 5 minutes) can be administered in oncology office (POS 11) with a 15-minute observation. Home administration is uncommon — Phesgo requires a trained healthcare professional for SC injection and a 15-30 minute observation, which is impractical in unattended home settings. Once payer site-of-care steering matures, Phesgo's SC delivery makes office (POS 11) the dominant setting; HOPD use is mostly reserved for loading dose monitoring or when chemotherapy is co-administered.

What is the Medicare reimbursement for J9316?

For Q2 2026, the Medicare Part B payment limit for J9316 is $60.225 per unit (10 mg, ASP + 6%). The 1,200 mg pertuzumab loading dose reimburses at approximately $7,227.00 per administration (120 units × $60.225); the 600 mg pertuzumab maintenance dose at approximately $3,613.50 per administration (60 units × $60.225). Annualized cost (Medicare ASP+6%) for a year of q3w maintenance (1 loading + ~16 maintenance): approximately $65,043 in Phesgo drug cost. Sequestration (~2%) reduces actual paid to roughly ASP + 4.3%. ASP is updated quarterly by CMS.

Is Phesgo always given with chemotherapy?

Not always. The FDA-approved indications vary: HER2+ metastatic breast cancer (1L) requires co-administration with docetaxel until disease progression; HER2+ early breast cancer (neoadjuvant) requires a chemotherapy backbone for the cycles before surgery; HER2+ early breast cancer (adjuvant, after chemo completion) is given as Phesgo monotherapy for the remainder of the 1-year total HER2-targeted therapy. Verify the line of therapy and combination regimen from the prescriber's order before billing — chemo coadministration affects admin coding (separate chemo IV admin lines) and site of care (HOPD typically required when chemo is co-administered).

Source documents

1. Genentech Access Solutions — Phesgo Coding & Coverage HCP page
   Document footers: Genentech Codes & Coverage 2026
2. FDA Phesgo prescribing information (BLA 761170, June 2020)
   Initial FDA approval label for the SC fixed-dose combination
3. DailyMed — PHESGO (pertuzumab, trastuzumab, and hyaluronidase-zzxf) injection, solution
   setid 27dd5e6b-72cd-458d-a015-cf4dab5800da; label rev December 5, 2025; three boxed warnings (cardiomyopathy, embryo-fetal toxicity, pulmonary toxicity)
4. FDA — Approval announcement for Phesgo (June 29, 2020)
   FDA Resources for Approved Drugs — Phesgo HER2+ breast cancer indication
5. FeDeriCa Phase III non-inferiority trial (NCT03493854)
   Pivotal pharmacokinetic non-inferiority trial supporting Phesgo SC vs IV Perjeta + Herceptin approval
6. CMS — Medicare Part B Drug ASP Pricing File
   Q2 2026 quarterly file, effective April 1 – June 30, 2026 — J9316 ASP+6% per 10 mg
7. SEER CanMED — HCPCS J9316 reference
   Permanent J-code effective 7/1/2021; HCPCS short descriptor "Pertuzu, trastuzu, 10 mg"
8. UnitedHealthcare — Oncology Medication Clinical Coverage Policy (covers Phesgo)
9. Aetna CPB — HER2-Targeted Therapies for Breast Cancer (covers Phesgo, Perjeta, Herceptin)
10. NCCN Clinical Practice Guidelines in Oncology — Breast Cancer
11. FDA National Drug Code Directory

About this page

We maintain this page as a living reference. Medicare ASP pricing is bound to our underlying CareCost data layer and refreshes automatically when CMS publishes new quarterly files. Coding and policy content is reviewed at least quarterly and updated whenever a source document changes.

Found an error? Email hello@carecostestimate.com.

Refresh cadence

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Change log

• May 22, 2026 — SME audit pass. Added DailyMed setid and current label-revision date (Dec 5, 2025). Confirmed ASP, dosing, unit basis, and triple boxed warning. Initial publication. ASP data: Q2 2026 (J9316 ASP+6% = $60.225 per 10 mg pertuzumab unit). Manufacturer source: Genentech Access Solutions Mar 2026. FDA label: BLA 761170 (June 29, 2020 approval). HER2+ breast cancer indications (1L MBC with docetaxel, neoadjuvant early breast, adjuvant early breast). Cross-linked to IV component pages /drugs/perjeta (J9306) and /drugs/herceptin (J9355).

Methodology

Every claim on this page is sourced inline. Pricing reflects the current CMS Part B Drug ASP Pricing File. Payer policies are read directly from each payer's published medical/pharmacy policy documents. Indication list is verified against the current FDA label and NCCN Breast Cancer guidelines. Cross-product comparisons (Phesgo SC vs Perjeta + Herceptin IV) are constructed from FDA labels and CMS HCPCS descriptors. We do not paraphrase from billing-software vendor blogs.