Background: Chimeric antigen receptor T cell therapies (CAR-T), while transformative, are expensive, require specialty center treatment, and impose patient safety restrictions that are barriers to patient access. The Fred Hutchinson Cancer Center (FHCC) Immunotherapy (IMTX) program delivers all CAR-T at the FHCC Seattle campus and is the primary CAR-T site for Washington (WA) and Alaska (AK), a region that encompasses dense urban and remote rural areas. In 2024, FHCC IMTX implemented changes to expand clinic capacity and reduce referral wait time. Here we analyze referral patterns and access to treatment pre-implementation as a baseline for measuring impact of program enhancements and to identify nonclinical access barriers that should be addressed for this region.

Methods: We retrospectively analyzed data collected by FHCC IMTX Intake coordinators on all referrals between 3/2016 and 3/2024. Data included basic demographics (age, city, state, diagnosis), referral source, and outcomes. Focused chart review was conducted in a subset of cases. Preliminary analyses of attrition from IMTX referral to arrival to subsequent treatment are presented here.

Results: In total, there were 986 referrals for patients with B cell or plasma cell neoplasms (917 WA, 68 AK) to FHCC IMTX from 2016-2024. A subset (WA 5%; AK 4%) were “inquiry only” or misrouted requests not aimed at establishing care. The remaining 942 IMTX referrals were from within FHCC (WA 73%; AK 48%), community oncologists (WA 24%; AK 48%), and self (WA 3%; AK 4%). Referral attrition (referrals not arriving to IMTX) occurred in 293 WA and 24 AK cases. Referral attrition was due to clinical considerations in 210 (71%) WA and 16 (67%) AK patients and included: excessive disease burden, poor performance status, and/or co-morbidities (60%); no available trial or commercial CAR-T (19%); and receiving other treatment (17%). Nonclinical reasons for attrition were also frequent (16% WA, 21% AK), most often “patient preference,” which on review of referral notes included: preference for another therapy, sometimes explicitly for CAR-T toxicity concerns (15%); concerns about finances, caregiver and/or travel requirements, or other social constraints (30%); insurance problems (9%); and other unstated reasons (17%). An initial inquiry into the role of proximity to the FHCC IMTX campus in King County, WA (KC) did not suggest large impact: KC residents were 28% of all WA referrals and constituted 23% of WA referral attrition, 31% of arrivals, and 32% of CAR-T recipients.

Of the referrals, 583 (67%) from WA and 41 (63%) from AK had an initial FHCC IMTX consultation and 56% WA and 52% AK arrived to IMTX for treatment. These arrivals represented 85% and 83% of completed consults, respectively. Subsequently, 438 (89%) WA and 28 (82%) AK arrivals received CAR-T. 303 patients (65%) received a commercial product; 155 (35%) were treated on a clinical trial. Among WA arrivals not receiving CAR-T (11%), reasons were rapid disease progression (4%), serious comorbidities or complications precluding CAR-T (2%), ineligibility (3%), manufacturing failure (1%), withdrawal due to proximity, visit frequency, and/or caregiver requirements (1%), and randomization to no CAR-T on clinical trial (0.2%). Reasons for AK arrivals not receiving CAR-T (18%) were ineligibility (12%), rapid progression (3%), and insurance issues (3%).

Conclusions: Although <60% of WA and AK FHCC IMTX referrals in this historical cohort converted to arrivals, most (>80%) arrivals received CAR-T. Referral attrition and arrival without treatment were most often related to disease progression. Expanded capacity at FHCC in 2024 has reduced IMTX wait times and should enable patients to receive CAR-T earlier in their disease course, with appropriately targeted referral networks in the region. Patient preference also influenced referral attrition. Recent reduction in monitoring, driving, and proximity requirements for some CAR-T should alleviate some patient and referring provider concerns and may influence requirements for other products. Analysis of sociodemographic and geographic factors, including distribution of patients and oncology providers, associated with referral and treatment attrition is ongoing. Future directions include surveying patients and oncology providers to identify other barriers to CAR-T, and designing interventions to enhance CAR-T access in the WA/AK region based on input from patients and communities at risk.

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2025
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