The US is not one payer. It is a commercial market segmented by plan, a Part B buy-and-bill channel, and a Part D pharmacy benefit — and an asset can win in one and lose in another.
Access in the United States is decided by benefit design before it is decided by evidence. An infused specialty product runs through Part B at ASP plus a percentage and is dispensed by the site of care; an oral runs through Part D and a pharmacy benefit manager's formulary. The same molecule can face a step edit in one channel and none in the other, and the difference is worth more than most efficacy margins.
Three forces now shape the picture. Prior authorisation and step therapy gate most specialty categories, with the criteria — not the label — defining who is actually treatable. Cost-effectiveness review by ICER sits outside the coverage decision but anchors the public argument about price. And Inflation Reduction Act negotiation has begun resetting list prices across selected products, with the orphan-drug exclusion shielding some rare-disease assets from it entirely — a distinction that decides whether a franchise faces a price cut at all.
AXLRx US reports are built around those mechanics. They set out the channel an asset will actually be reimbursed through, the prior-authorisation criteria that gate it, the comparator set payers will hold it against, and where the coverage argument is won.
Lecanemab versus donanemab in early AD. CMS amyloid-confirmation coverage and ARIA monitoring as the access gate.
Dupilumab's 70% biologic share against JAK step-edits. A two-tier US payer landscape for IL-4Ra biologics and oral JAKs.
Rezdiffra and Wegovy now split the noncirrhotic MASH label. This is a Year 0 to Year 1 access and retention fight, not a pre-launch window.
Four approved IO agents split 1L NSCLC into three PD-L1 cohorts. Pembrolizumab holds an estimated 52% share ahead of 2028 patent expiry.
US NSCLC segments by histology and biomarker before it segments by drug. This maps where patients are actually diagnosed and tested, and where the gap between diagnosis and treatment costs them.
Incidence-to-eligible NSCLC funnel by cohort with sourced conversion assumptions and a share waterfall.
CMS routes all four approved 1L NSCLC IO agents through Part B buy-and-bill at ASP+6%. But PD-L1 assay requirements split coverage into three distinct biomarker-testing tiers.
Tirzepatide 20.9% versus semaglutide 15.3% weight loss. The Medicare coverage gap and commercial step-edit reality.
Iptacopan oral pivot versus the anti-C5 IV class. Orphan-drug exclusion from IRA negotiation (US), NICE HST (UK) and SFDA lag (GCC).
PNH diagnosis pathway, FLAER flow-cytometry bottleneck and the treated-prevalent pool across US centres.
Why the orphan-drug exclusion shields anti-C5 agents from IRA negotiation, ICER's 2024 value verdict on iptacopan, and Part B vs Part D routing.
Tirzepatide takes 41% of new GLP-1 starts; SELECT CV indication and IRA negotiation reshape US formulary access.
From zero disease-specific drugs to five in three years: how endothelin, complement and APRIL inhibitors are redrawing the IgAN market.
The prophylaxis class is fracturing along route: oral berotralstat and the first oral on-demand agent against a still-injectable antibody field.
Tafamidis's ATTR-CM monopoly meets acoramidis — while the orphan-drug exclusion keeps the stabilizer class out of IRA price negotiation.
Tc-PYP scintigraphy, not biopsy, is now the diagnostic gate in ATTR amyloidosis. This maps the ATTR-CM versus ATTR-PN split and the wild-type/hereditary divide across a largely undiagnosed population.
US IgA nephropathy has shifted from RAS-blockade supportive care to five disease-modifying therapies. This maps the epidemiology and the biopsy-and-proteinuria diagnostic gate that still controls who reaches them.
Tafamidis is shielded from IRA negotiation by the orphan-drug exclusion. ICER judged its ~$268K price ~85–95% too high, and acoramidis plus pending generics are the real net-price levers.
US payers gate the five FDA-approved IgAN therapies on biopsy, proteinuria and RAS-blockade step-through. The Filspari REMS, Part D routing and the ICER 2026 assessment set the rest of the access path.
Specialty-tier prior authorization, prophylaxis above $300K/patient/yr, ICER 2018/2021 value-based benchmarks and no-concurrent-acute-agent rules.
HAE pathophysiology, the Type I/II split, attack burden and the diagnostic-delay problem that defines the US in-market landscape.
ICER priced efgartigimod's value at $18,300–28,400 a year, under half its ~$418,400 launch cost. That gap is hardening into a three-tier FcRn-to-C5 step-edit across US commercial plans.
Neuromuscular-junction autoantibody biology, the AChR/MuSK/seronegative split, and the crisis burden that defines US gMG.
Three novel mechanisms in 24 months — FcRn antagonists vs C5 inhibitors, and the AChR+ vs MuSK+ line that segments the market.
SCD epidemiology, genotype mix, VOC and organ-damage burden, and the 22-year life-expectancy gap across the US in-market population.
Pegunigalsidase now challenges Fabrazyme's two-decade lead in US Fabry disease. Two IV enzyme replacement therapies meet an oral chaperone only ~35–50% of patients can take.
Gaucher type 1 epidemiology, the Ashkenazi Jewish founder burden, GBA1 genotype–phenotype, and the 20-fold Parkinson's risk.
Gene-therapy access at $2.2–3.1M, the CMS Cell & Gene Therapy Access Model, VOC-freedom endpoints, and the hydroxyurea step-edit.
Zolgensma's $2.125M one-time cost, outcomes-based Medicaid contracts, and Part B vs Part D routing across three SMA modalities.
US incidence 1 in 15,700, de novo SCN1A genetics, and one of the highest SUDEP rates documented in epilepsy.
Five FDA-approved Gaucher type 1 therapies (three IV enzyme replacement vs two oral substrate reduction) and eliglustat's oral first-line pivot.
Fabry disease splits into classic childhood-onset and a largely undiagnosed later-onset cardiac form. An X-linked organ timeline and the ~35–50% amenable-mutation gate decide who is treatable.
SMN1/SMN2 biology, the Type 1–4 severity spectrum, and how newborn screening splits SMA into pre-symptomatic and symptomatic populations.
Two Dec-2023 gene therapies (Casgevy, Lyfgenia) reset a ~100,000-patient market, while voxelotor's 2024 withdrawal thins the oral field.
Cold agglutinin disease is a rare classical-complement autoimmune haemolytic anaemia driven by cold-reactive IgM. This separates primary CAD from cold agglutinin syndrome and sizes the US haemolysis burden.
GAA-deficiency biology, the LOPD-versus-IOPD split, the years-long diagnostic delay, and newborn screening across the US Pompe population.
Sutimlimab (Enjaymo) is a ~$260K+/year Part B IV biologic in a few-thousand-patient population — and not cost-effective at the current price.
Sutimlimab (Enjaymo) is the only FDA-approved CAD therapy — competing against off-label rituximab-based standard of care, not a branded rival.
Fintepla's list price runs roughly 3x Epidiolex, and payer scrutiny turns on high WAC against a small, severe paediatric population.
IV enzyme replacement buy-and-bill under Part B vs oral SRT under Part D, the CYP2D6 PA gate, and generic miglustat.
Pompe ERT costs near $400,000 a year in Part B, and remains the only major rare-disease ERT category ICER has never reviewed. Pombiliti + Opfolda splits into two simultaneous prior authorisations across Part B and Part D.
Fenfluramine leads on efficacy, cannabidiol anchors the lower-cost branded option, and stiripentol holds the adjunct niche.
Three mechanisms chase one SMN target: a one-time $2.125M gene therapy, chronic intrathecal ASO, and daily oral. Newborn screening resets the battlefield.
A genetic test gates oral migalastat, and IV enzyme replacement sits in Part B. Fabrazyme has no US biosimilar, and the IRA's orphan-drug exclusion shields it from Medicare price negotiation.
Two next-generation ERTs are moving to displace alglucosidase alfa in US late-onset Pompe disease. Avalglucosidase alfa and cipaglucosidase alfa plus miglustat now define the competitive set.
The MASLD-to-MASH-to-F2-F3 funnel, NASH-CRN fibrosis staging, and the FIB-4-to-elastography diagnostic gap behind the 6.7M label-eligible pool.
US atopic dermatitis epidemiology — 16.5M adults, the moderate-to-severe pool, and the atopic march that frames the biologic-eligible segment.
Topical-then-biologic step-therapy, JAK black-box PA gates, ICER's dupilumab-aligned and JAK-discount verdicts, and why Dupixent is not IRA-selected.
Why Rezdiffra's $47,400 WAC lands inside ICER's value range, why the IRA reset hits semaglutide first, and how Part D routing shapes MASH access.
38.4M US adults, an 8.7M undiagnosed pool, and complication burden driving GLP-1 and SGLT2 organ-protection strategy.
Type 2 Diabetes is IRA ground zero: three orals negotiated for 2026, semaglutide at $274 for 2027, and the class price anchor reset.
US Alzheimer's staging, the amyloid-confirmation diagnostic pathway, and the FDA-cleared plasma pTau-217 blood test resizing the addressable pool.
CMS's coverage-with-evidence-development registry, not IRA negotiation, is the anti-amyloid access gate. ICER's below-value verdict and Part B routing set the rest.
US adult obesity at 41.9% (CDC NHANES). BMI-class distribution, severe-obesity burden, and the comorbidity segments that drive coverage.
Medicare covers Wegovy only for cardiovascular risk, not obesity alone. The IRA's IPAY 2027 semaglutide price applies across the franchise, and ICER returned a 2025 'high value' verdict.
Two 2024 approvals moved the COPD maintenance fight past the inhaler for the first time in a decade. Ensifentrine and dupilumab split the market into an inhaler base and a biology-defined add-on tier.
COPD is a large, under-diagnosed, exacerbation-driven US disease that has just become biomarker-stratified. The blood eosinophil count now decides which of ~14 million diagnosed adults can reach a biologic.
COPD access is a pharmacy-benefit story: inhalers and biologics run through Medicare Part D and commercial PBMs, not medical coverage. Step edits gate the base, an eosinophil threshold gates the biologic, and the IRA is reshaping both price exposure and negotiation risk.
Six mechanisms now compete for moderate-to-severe plaque psoriasis in the US, and the efficacy bar has moved from PASI 75 to PASI 90. IL-17A, dual IL-17A/F, IL-23p19, IL-12/23, TNF and oral TYK2 all hold ground.
Psoriasis affects about 3.0% of US adults, roughly 7.55 million people. Only the moderate-to-severe minority reaches the systemic and biologic therapies that define the commercial market.
US access to plaque psoriasis biologics is gated by step therapy and reshaped by two forces landing together. IRA price negotiation on Stelara and Enbrel, and biosimilar erosion of adalimumab and ustekinumab.
Only ribociclib has posted consistent overall-survival wins in the three-way first-line CDK4/6 contest. MONALEESA-2 showed 63.9 versus 51.4 months (HR 0.76). The real competition has moved downstream, where 2023 approvals of an oral SERD and an AKT inhibitor carve the post-CDK4/6 line by biomarker.
HR+/HER2- is the largest breast cancer subtype, roughly 68% of the estimated 317,000 new US invasive female cases in 2025. Most present early and are curable, but 20-30% recur to metastatic disease where five-year survival falls to about a third, making biomarker testing (ESR1, PIK3CA) the fork that determines the treatment path.
The price ceiling for HR+/HER2- oral therapies is now set directly by the government. Palbociclib was selected for Medicare negotiation with a 50% cut, $15,741 to $7,871, effective 2027. Access runs through Part D and commercial prior authorization, and newer targeted agents face biomarker-gated coverage with cost-effectiveness ratios far above accepted thresholds.
NSCLC is a specialist, buy-and-bill oncology market, not a mass-reach primary-care one. A concentrated medical-oncology prescriber base, biomarker-gated prescribing, and infused immuno-oncology under Medicare Part B dictate a small, account-based key-account and MSL field model.
Two withdrawals opened a 55,000–65,000-patient white space in Sickle Cell Disease — speed, not differentiation, is the binding constraint.
US SMA sizing splits into two live populations, not one number. 8,000-10,000 prevalent patients across Types 1-4, and a separate 500-700-patient Zolgensma-treated cohort now aging into a monitoring window where 15-20% show early motor plateau.
An estimated 8,000-9,000 Americans have HAE, and only 35-40% receive any prophylaxis. That leaves 2,500-4,000 attack-eligible patients never treated, a pool nearly as large as the entire treated population.
The 1,400–2,000-patient refractory Dravet cohort is the opening. REMS-free cardiac safety and a 45%-Medicaid access plan decide who reaches it.
100,000-200,000 US gMG patients narrow to a 4,000-6,000 on-FcRn-therapy pool, and 1,200-2,100 of them remain inadequately controlled despite treatment.
Ensifentrine and dupilumab, both approved in 2024, already own the exacerbator add-on tier. A new entrant must clear a 31-41% exacerbation-reduction bar and pick a phenotype-agnostic or eosinophil-gated lane before it competes on anything else.
Binding constraint: grow the never-prophylaxed cohort before donidalorsen resets the oral efficacy bar — not switch stable lanadelumab patients.
8,000-10,000 US SMA patients split roughly 60/27/13/under 5 percent across Types 1-4. The 500-700-patient Zolgensma cohort is what this funnel validates against.
Binding constraint: beat iptacopan's oral bar in the EVH-anaemia cohort anti-C5 can't resolve — inside a pricing ceiling iptacopan already set.
The post-CDK4/6 line in HR+/HER2- metastatic breast cancer is fragmented by biomarker. Elacestrant's own cost-effectiveness analysis found it 58 times above the standard willingness-to-pay threshold. That precedent is the bar a new targeted entrant must clear.
An estimated 8,000-9,000 Americans live with hereditary angioedema. Just 35-40% receive any prophylaxis, leaving 2,500-4,000 patients who meet treatment criteria untreated, the funnel this model sizes precisely.
Sutimlimab's CARDINAL trial left 46% of patients without a haemoglobin response. The two most-advanced next-generation complement inhibitors then abandoned cold agglutinin disease after its launch, leaving the entry gap defined by non-response and cost, not a clinical rival.
15,000-20,000 Americans carry a PNH clone, but only about 3,500 reach complement-inhibitor therapy. Up to 1,200 of them stay anaemic on it. This model sizes every gap in between.
Five approved Type 1 Gaucher therapies treat the body, not the brain. A genotype gate locks a meaningful share of the highest-prevalence population out of the only oral option, and a Phase 3 gene therapy trial is now racing to close that gap.
Binding constraint: eGFR-confirmed evidence beats a second accelerated approval on UPCR surrogate data alone.
Binding constraint: capture newly diagnosed ATTR-CM volume and survive ICER's steepest value gap in the rare-disease basket.
Binding constraint: address FcRn-inadequate responders or claim a serostatus niche — efgartigimod sets both the clinical and ICER pricing bar.
The ADA-positive suboptimal-agalsidase-responder niche (200–400 US patients) is Fabry's only clean pre-launch opening.
Roughly 5,000-10,000 diagnosed US Fabry patients split first by GLA amenability, with 35-50% oral-eligible. ADA status narrows that to a precise 200-400 patient addressable niche, which a Fabrazyme-anchored $250-350K WAC makes commercially calculable.
Casgevy and Lyfgenia list at $2.2M and $3.1M, but the sticker price is not what gets paid. CMS's Cell and Gene Therapy Access Model, Medicaid concentration, and a $1.5-1.9M ICER ceiling decide the realised net.
US Dravet incidence of 1 in 15,700 births is consistent with the Dravet Syndrome Foundation's 6,000-8,000 prevalence estimate. Only 35-40% of that population, 1,400-2,000 patients, remains inadequately controlled on today's two branded agents.
Lanadelumab lists near $450,000 a year against berotralstat's roughly $95,000. ICER's 2021 fair-value benchmark for berotralstat lands almost exactly on that list price, and the three 2025 entrants carry no ICER anchor of their own.
Two anti-amyloid agents already sit inside CMS's coverage-with-evidence-development registry. A new entrant inherits that gate and must price inside ICER's benchmark to avoid Aduhelm's fate.
5,000-10,000 diagnosed US classic Fabry patients face a 35-50% amenable-mutation gate to oral therapy. The treated population is still 60-65% on enzyme replacement. This funnel starts at diagnosis because no defensible undiagnosed estimate exists yet.
6,000-8,000 US Dravet patients, roughly three-quarters SCN1A-confirmed. 35-40% are still inadequately controlled on cannabidiol plus fenfluramine, the population any new agent must actually reach.
A fourth SMA drug has no room in the broad market — the opening is the 500–700-patient Zolgensma-attenuation cohort with no PA pathway yet.
Tirzepatide's 41% new-GLP-1 share and semaglutide's SELECT label set the efficacy and label bar. A new entrant must clear both while an IRA-reset price anchor is closing in behind it.
Bimekizumab already clears PASI 90 in 85% of patients at week 16. A new plaque psoriasis entrant has to win on dosing interval or route, not incremental clearance, against an incumbent price anchor the IRA has already cut 66-67%.
316,950 annual US invasive breast cancer diagnoses and a 6.0% metastatic-at-diagnosis rate size the incident flow. Layering CDK4/6-inhibitor and post-progression pricing onto that flow, and onto the separate, larger recurrence pool, is what turns a patient count into a market value.
6.7 million Americans have F2-F3 MASH, but Rezdiffra has already reported 42,250+ patients on therapy and $311.3M in Q1 2026 revenue. This model triangulates population against real uptake, not a modeled guess.
IQVIA puts the 2023 US T2D drug market at $22B top-down. Triangulated bottom-up against 29.7M diagnosed patients out of 38.4M with the disease, the two methods converge, but per-class revenue split remains an open gap this model flags rather than invents.
Three IV enzyme replacement brands run ~$300,000/year with no generic rival, so preferred-ERT designation is the real pricing lever. Eliglustat's CYP2D6 gate and generic miglustat's trial-first rule complete the picture.
150,000 US IgA nephropathy patients, of whom 70,000-90,000 are biopsy-confirmed. Only 5,000-8,000 are on novel therapy today, while 15,000-25,000 patients with UPCR above 1g/g remain the addressable high-risk cohort this model sizes precisely.
All five FDA-approved IgAN therapies clear the same prior-authorisation gate, not a negotiated rebate table. That gate is biopsy-confirmed diagnosis, UPCR 0.8-1.5 g/g, eGFR 30 or higher, and RAS-blockade step-through. No formal net-price data exists because access here runs on step-therapy criteria, not payer negotiation.
Fabrazyme's orphan-drug exclusion under the IRA shields it from Medicare price negotiation entirely. No rebate or net-price figure is disclosed anywhere in the primary record for any Fabry therapy. The orphan exclusion, not a discount ladder, is what a Fabry pricing strategy has to be built around.
Wegovy lists at roughly $1,349 a month, but CMS pays $274 for a 30-day semaglutide supply from 2027. That 71% cut applies to Ozempic, Rybelsus and Wegovy alike. Tirzepatide sits outside the negotiation entirely, for now.
Rezdiffra and Wegovy already hold the noncirrhotic F2-F3 label. The clearer opening for a new entrant is the compensated-cirrhosis boundary neither drug covers.
Pembrolizumab holds an estimated 52% of first-line NSCLC on five years of precedent. Payers evaluate every new IO or targeted asset against KEYNOTE, CheckMate and IMpower coverage policy, not against a fresh trial design.
Two IRA negotiation cycles have now cut across the T2D formulary. Januvia down 79% to $113, Jardiance down 66% to $197, Farxiga down 68% to $178 from January 2026, and semaglutide down 71% to $274, with Janumet and Tradjenta added for 2027.
US cold agglutinin disease sizing starts from a rate range, not a point estimate. Incidence 0.6-1.2 and 1-year prevalence 1.4-3.1 per 100,000 imply ~5,000 prevalent patients. No published treated-share figure exists to split served from total addressable.
Stelara's negotiated price falls to $4,695 from a $13,836 list, a 66% cut, effective January 2026. That is the same month ustekinumab biosimilars begin launching. Two separate pricing shocks land on one legacy biologic at once.
6,000 US Type 1 Gaucher patients size a market near $1.8 billion at ERT pricing. That MedlinePlus-sourced population sits inside a genetic sub-segment where Ashkenazi carrier frequency runs 1 in 12-15, against a general-population disease frequency of just 0.70-1.75 per 100,000.
Iptacopan's ~$550,000 annual WAC sits roughly 71% above ICER's $156,000-157,000 value-based benchmark. The orphan-drug exclusion keeps anti-C5 incumbents outside IRA's reach entirely. Those are the two forces any new US PNH entrant must price against.
375–600 US LOPD patients are failing next-gen ERT — ADA superiority and first-line labeling decide who can reach them.
Sutimlimab costs $259,000-$302,000 per patient per year. A peer-reviewed analysis puts its ICER at $2.34M/QALY, with standard of care favoured in all 10,000 probabilistic-sensitivity iterations. The value gap, not a rival drug, sets the pricing discipline.
US PNH prevalence spans 15,000 to 20,000 patients across three phenotypes, but only about 3,500 are on complement-inhibitor therapy. A 2.4-year average diagnostic delay, plus 200 to 400 patients a year undertreated at non-PNH centres, accounts for most of that gap.
Fintepla's weight-based list price runs roughly 3x Epidiolex. Payers work that gap through step-edit design layered on Part D pharmacy-benefit routing, and no generic cannabidiol reaches the US market before the late 2030s.
500,000+ US patients aged 70+ with HFpEF carry undiagnosed ATTRwt-CM, against only 70,000-100,000 diagnosed and treated. Two further sub-populations, Val122Ile carriers and ATTR-PN, remain even less visible.
An estimated 150,000 Americans have IgA nephropathy, but only 70,000-90,000 are biopsy-confirmed. Just 5,000-8,000 are on a disease-specific therapy today, within a 15,000-25,000-patient high-risk eligible cohort.
Dupilumab's 70% share sets the biologic entrenchment bar. The 2022 JAK boxed warning sets a second, harder gate for any oral entrant.
Wegovy and Zepbound already occupy the injectable position. A new entrant must clear the 20.9% efficacy bar and price beneath the $274 IRA reset arriving in 2027.
US Pompe prevalence runs 5,000 to 10,000 patients, 70-80% late-onset. Of the roughly 2,000 LOPD patients on enzyme replacement therapy, 375 to 600 are inadequate responders, the addressable population any new agent must reach.
Tafamidis prices 12-17x above ICER's fair-value benchmark, yet the orphan-drug exclusion keeps it out of IRA negotiation. Acoramidis and pending generics, not Medicare, now set net price.
A 9,146-patient US real-world study found no significant survival difference between palbociclib, ribociclib, and abemaciclib. When the drugs perform equivalently, KOL guidance decides which one gets prescribed, not clinical data.
An estimated 100,000 US sickle cell patients narrow to a 55,000-65,000-patient pool with no adequate novel therapy. Only 50-100 of the gene-therapy-eligible minority were actually treated in year one.
5,000-10,000 Americans live with Pompe disease. Roughly 2,000 late-onset patients are on enzyme replacement therapy, and 375-600 of them, one in four, are inadequate responders, the subtype this model is built to size.
Pompe ERT WAC runs near $400,000 a year, and the Pombiliti + Opfolda regimen splits across Medicare Part B and Part D. Zero ICER reviews exist today, with one expected in 2025 and a 12-month J-code lead time for any new entrant.
Ibrance's Medicare-negotiated price takes effect a full year before Kisqali's and Verzenio's. Three clinically equivalent drugs, staggered IRA negotiation cycles, means Pfizer sets the reference point Novartis and Lilly then have to negotiate against.
ICER priced efgartigimod's value at $18,300-28,400 a year, under half its ~$418,400 assumed launch price. That gap is hardening into a three-tier step-edit staircase across US commercial and Part B plans.
316,950 new US invasive breast cancer diagnoses in 2025. Only 6.0% present as metastatic at diagnosis, but 73.9% of the metastatic population is HR+/HER2-, the subtype this model is actually built to size.
A ~100,000-patient US SCD population narrows to a 55,000-65,000-patient addressable white space. Only 50-100 gene-therapy patients were actually treated in the first 12 months, versus 200-300 projected.
Zolgensma's $2.125M sticker price obscures the real US SMA pricing lever. A 10-state Medicaid outcomes-based annuity pays $212,500 a year for ten years, set against chronic Spinraza and Evrysdi costs and a Part B/Part D routing split that changes patient cost by drug.
An estimated 500,000+ US patients aged 70+ have undiagnosed ATTRwt-CM, against only 70,000-100,000 currently diagnosed and treated. A separate 100,000+ Val122Ile hereditary carrier pool sits alongside it.
US gMG prevalence runs 100,000-200,000, but only 4,000-6,000 patients are on FcRn therapy today. 1,200-2,100 of those remain inadequately controlled. The near-term opportunity is the funnel gap, not the epidemiology total.