Independent Market Access and Reimbursement Risk Assessment.

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Dostarlimab / jemperli for treating primary advanced or recurrent endometrial cancer with high microsatellite instability or mismatch repair deficiency

As of May 2025, MARA’s assessment finds Dostarlimab / Jemperli’s reimbursement risk concentrated in uncertainty, sensitivity, and broader impacts, with comparator selection a strength; the current MARA Rating and full rationale are available in the report.

The assessment also weighs evidence quality and robustness: how solid the underlying evidence is on its own terms — trial design, size and endpoints — before any question of price is reached. The strength recorded in comparator selection carries weight because that domain asks whether the drug was tested against the treatment payers actually fund today; a benefit shown against the wrong comparator carries little weight in a reimbursement decision.

Oncology

This rating sits within MARA’s Oncology coverage, alongside 153 other independently assessed treatments in the same area.

What payers will ask

Is the clinical benefit the kind payers reward? — Clinical effectiveness

The clinical evidence from the RUBY-1 trial indicates that dostarlimab combined with platinum-based chemotherapy significantly improves progression-free survival (PFS) compared to standard chemotherapy alone, with a hazard ratio of 0.28, indicating a 72% reduction in the risk of progression or death. However, the evidence for overall survival (OS) is less mature, leading to some uncertainty about long-term benefits.

Does the economic case hold at the expected price? — Cost effectiveness

The economic model suggests that the most likely cost-effectiveness estimate for dostarlimab is within NICE’s acceptable range, approximately £20,000 per QALY gained. This indicates that the therapy is marginally cost-effective, although uncertainties remain regarding the robustness of the economic model.

Is there quality-of-life evidence payers weigh? — Quality of life

While specific HRQoL data is not extensively detailed in the document, patient expert testimonies suggest that dostarlimab presents minimal additional treatment burden and allows patients to maintain an active life. This indicates a moderate improvement in quality of life, although direct evidence from validated tools is lacking.

Does the safety profile hold up for payers? — Safety and Adverse Effects

The safety profile of dostarlimab appears favorable, with patient reports indicating that adverse events are mostly minor and transient. The committee noted that the treatment does not significantly increase the treatment burden compared to standard chemotherapy.

Was the drug compared against what payers expect? — Comparator Selection

Dostarlimab was compared against the appropriate standard of care, which is platinum-based chemotherapy. The trial design included a placebo-controlled arm, enhancing the validity of the comparison.

Is the population defined the way payers need it? — Patient Population and Subgroups

The trial population is representative of the intended patient population with advanced or recurrent endometrial cancer, specifically those with high microsatellite instability or mismatch repair deficiency. However, there are some concerns regarding the small sample size.

Does the drug fit how care is delivered and paid for? — Care Pathway Integration

Dostarlimab can be integrated into existing treatment pathways with minimal disruption, as it is used in combination with standard chemotherapy. The committee noted that no new infrastructure or extensive training is required for its implementation.

Are the wider system costs understood? — Resource Use and Cost Implications

The resource implications of introducing dostarlimab are manageable, with the potential for cost savings due to its effectiveness. The economic model indicates that the budget impact is justifiable given the expected health outcomes.

Would the evidence survive payer scrutiny? — Evidence Quality and Robustness

While the RUBY-1 trial provides important evidence, concerns about the small sample size and potential biases due to misclassification of patient status raise questions about the robustness of the findings. The evidence is strong but not without limitations.

How exposed is the case to uncertainty? — Uncertainty, Sensitivity, and Broader Impacts

There are significant uncertainties regarding the long-term benefits of dostarlimab, particularly concerning the durability of treatment effects and the appropriateness of the economic model assumptions. These uncertainties could impact decision-making.
This rating replaces the earlier March 2022 rating of the same drug and indication — still on the record here.

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