Cost utility analysis of tisagenlecleucel vs salvage chemotherapy in the treatment of relapsed/refractory diffuse large B-cell lymphoma from Singapore’s healthcare system perspective

Figures & data

Figure 1. Decision tree structure. Abbreviations. r/r DLBCL, relapsed or refractory diffuse large B-cell lymphoma; SCT, stem cell transplant; PSM, partitioned survival model.

Figure 2. Partitioned survival model with three health states.

Figure 3. Modelled treatment strategies. Abbreviations. R-CHOP, Rituximab, cyclophosamide, doxorubicin, vincristine, prednisone; RT, radiotherapy; SCT, stem cell transplant; R-ICE, rituximab, ifosfamide, carboplatin, etoposide, mesna and peg-filgrastim; R-DHAP, rituximab, dexamethasone, cytarabine, cisplatin and peg-filgrastim; R-GDP, rituximab, gemcitabine, dexamethasone and cisplatin; BEAM, carmustine, etoposide, cytarabine, melphalan; CR, complete response; PR, partial response.

Table 1. Summary of cost and benefits of tisagenlecleucel versus chemotherapy in base-case and additional scenario analyses.

Base-case	Tisagenlecleucel	Chemotherapy	Incremental
PFLYs	2.534	1.259	1.275
LYs	3.616	2.809	0.807
QALYs	2.064	1.556	0.508
Total Costs (US$)	297,911	39,536	258,375
ICER (US$ per LY gained)			320,200
ICER (US$ per QALY gained)			508,531
Scenario analyses
Survival modelling approach: Log-logistic mixture cure model + standardized mortality ratio of 1.0 after 5-year cure-point^a
PFLYs	3.086	1.259	1.827
LYs	5.233	2.809	2.424
QALYs	2.944	1.556	1.388
Total Costs (US$)	300,865	39,536	261,329
ICER (US$ per LY gained)			107,821
ICER (US$ per QALY gained)			188,292
Success rate of tisagenlecleucel infusion: 100%
PFLYs	3.336	1.259	2.077
LYs	4.414	2.809	1.604
QALYs	2.536	1.556	0.980
Total Costs (US$)	428,623	39,536	389,087
ICER (US$ per LY gained)			242,506
ICER (US$ per QALY gained)			397,188

Abbreviations. PFLY, progression-free life year; LY, life year; QALY, quality-adjusted life year; ICER, incremental cost-effectiveness ratio.

^a Under this scenario, 44% of patients were cured after 5-year and their standardized mortality ratio (SMR) was adjusted to match general population at 1.0. A higher SMR due to toxic effects from previous chemotherapy therapies was not applied as this was already factored in by a shorter lifetime horizon.

Figure 4. OWSA tornado diagram. Abbreviations. QALY, quality-adjusted life year; PF, progression-free; SMR, standardized mortality ratio; LT-survival, long-term survival; SCT, stem-cell transplantation; PD, progressed disease.

Figure 5. CEAC showing the likelihood of tisagenlecleucel being cost-effective compared to salvage chemotherapy across different WTP thresholds. Abbreviations. CEAC, cost-effectiveness acceptability curve; WTP, willingness to pay.

Table 2. Willingness-to-pay threshold analysis.

Willingness-to-pay threshold (US$)^a	Target price of tisagenlecleucel (US$)	Corresponding discount (%) from price point of ∼ US370K
∼37K/QALY	14,271	96
∼74K/QALY	42,244	89
∼111K/QALY	70,216	81
∼148K/QALY	98,189	74

^a These willingness-to-pay thresholds correspond to thresholds in local currency: S$50K, 100K, 150K and 200 K/QALY.