Fostamatinib,
does it really help with Increased stable platelet response in persistent or chronic immune thrombocytopenia?
research showsThe grade is C. Across FIT1 and FIT2, stable platelet response occurred in 18/101 (18%) versus 1/49 (2%), an absolute difference of 16 points, P=.0003. This was a laboratory response rather than bleeding benefit, and FIT2 alone was null at 18% versus 4%, P=.15. The evidence comes from a small manufacturer-only program, giving C with 50 points.
ads claimAn 18% platelet response is not an 18% reduction in bleeding. The primary endpoint was laboratory-based, bleeding scores were not significantly different, and the second trial failed its standalone primary analysis.
Useful facts when choosing a product
- Fostamatinib inhibits SYK rather than stimulating the TPO receptor.
- FIT1 and FIT2 were separate registrations within one manufacturer program, not independent replication.
- The drug and placebo were treatment materials; platelet testing and bleeding scales were assessment tools.
Chamgap Semantic Classification Code
Candidate index · review held
UNK.fostamatinib.UNK.stable-platelet-response-in-persistent-or-chronic-immune-thrombocytopenia.increase.placeboUnknown > Fostamatinib > Unknown > stable platelet response in persistent or chronic immune thrombocytopenia > Increase claim > Placebo
An automated migration candidate, not an issued permanent code; exact claim scope remains under review. This machine-generated migration candidate helps retrieval but is not a permanent assignment. The original verdict ID and URL remain authoritative.
What the research actually shows
FIT1 randomized 76 participants, 51 versus 25, and FIT2 randomized 74, 50 versus 24, in 2:1 double-blind placebo-controlled designs. All 150 randomized participants entered efficacy analysis; prespecified last-observation-carried-forward handling and a more conservative missing-as-failure sensitivity analysis were reported. Early discontinuation after week 12 for nonresponse was common, reaching 76% and 96% in the FIT1 fostamatinib and placebo groups. Rigel funded both trials and editorial support. VM, HZ, and AMD were Rigel employees with stock options, and HZ performed the statistical analysis. Fostamatinib and matching placebo were trial materials; no separate company-supplied assessment tool was reported. Avoidable limitations were the total sample below 200 and extensive discontinuation.
Why this is classified as C (50)
A positive pooled surrogate result from two small manufacturer-program trials, without independent replication and with a failed FIT2 standalone analysis, gives C with 50 points.
Counterpoint. C does not mean no drug activity. It means that stable responses in some refractory patients still require stronger evidence for bleeding, quality of life, and independent replication.
Rejudgment record. Cross-check applied — Treats FIT1 and FIT2 as separate registrations within one manufacturer program and accounts for the surrogate primary endpoint, failed standalone FIT2 result, pooled absolute difference, and attrition
| Endpoint | S | Surrogate marker - laboratory or imaging measures |
| Replication | R1 | Single confirmatory trial |
| Independence | I0 | Evidence comes only from manufacturer studies |
| Effect size | E+ | Meets the clinically important threshold |
Stored derived and displayed grades match; this is not a current recalculation or validity check (C).
Sub-claim grades by effect
This ingredient is marketed for several effects. A single overall grade blends strong and weak claims together, so each effect is graded separately here. The overall grade reflects the strongest disconfirming or core claim.
| Effect (sub-claim) | Grade | Basis |
|---|---|---|
| Increased stable platelet response | C | The pooled result was 18% versus 2%, but it is a manufacturer-only surrogate. |
| Reduced bleeding | D | IBLS and WHO bleeding scores showed no significant between-group difference. |
Cross-check — AI research and Codex final gate
Evidence Table
| Study | Design | Sample | Funding | Endpoint | Result | Weight |
|---|---|---|---|---|---|---|
| Bussel J et al. 2018 FIT1 | Multicenter 2:1 double-blind placebo-controlled phase 3 trial | 76 randomized and analyzed by intention to treat, 51 versus 25 | Fully funded by Rigel Pharmaceuticals, with company employees, statistical analysis, and editorial support | Stable platelet response during weeks 14 to 24 | 9/51 (18%) versus 0/25, absolute difference 18 points, 95% CI 7.2 to 28.1, P=.026 | Positive but small manufacturer trial |
| Bussel J et al. 2018 FIT2 | Multicenter 2:1 double-blind placebo-controlled phase 3 trial | 74 randomized and analyzed by intention to treat, 50 versus 24 | Fully funded by Rigel Pharmaceuticals within the same program as FIT1 | Stable platelet response during weeks 14 to 24 | 9/50 (18%) versus 1/24 (4%), absolute difference 13.8 points, 95% CI 0.5 to 27.1, original primary analysis P=.152 | Null standalone primary analysis; supports only the pooled estimate |
Receipt — 1 References
All 1 cited sources were verified for existence at the original page (as of 2026-08-18).
Final verification and publication gate: Codex · Evidence date: 2026-08-18 · Corrections: none
Cite this verdict
[Chamgap] Fostamatinib x stable platelet response in persistent or chronic immune thrombocytopenia — Evidence Grade C·50. 1 cited sources checked. Source: https://chamgap.com/en/verdicts/immunity/fostamatinib-persistent-chronic-itp-stable-platelet-response/ · CC BY 4.0CC BY 4.0 — free to use with attribution; do not distort grades, numbers, or verdict meaning.
What this document does and does not do
Chamgap is an information source. It reports what research has and has not confirmed; it does not tell readers what to take or buy. That decision belongs to readers and, when needed, medical or legal professionals. This verdict reflects literature available up to the search date and may change as new research appears. Nothing here is medical advice.