LCH Single-System Multifocal (Nodal) — SHARE Protocol with Prophylaxis Dosing (10 yr, 33 kg, BSA 1.16 m²)
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Langerhans cell histiocytosis SHARE protocol treatment
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Langerhans cell histiocytosis pediatric treatment protocol vinblastine
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LCH SHARE protocol multifocal single system vinblastine prednisolone dosing pediatric
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https://siope.eu/media/documents/escp-standard-clinical-prac…
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SHARE protocol LCH "single system multifocal" nodal vinblastine dose BSA prophylaxis cotrimoxazole
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SHARE protocol LCH "6 mg/m2" OR "vinblastine" "prednisolone" "40 mg/m2" pediatric dosing prophylaxis TMP-SMX
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SHARE LCH protocol "stratum" nodal single system multifocal prophylaxis PCP cotrimoxazole antifungal
Now I have enough information to construct the complete SHARE/LCH protocol dosing table. The "SHARE" protocol refers to the Histiocyte Society LCH-III/LCH-IV standard regimen (vinblastine + prednisolone ± mercaptopurine) — the term "SHARE" is also used in some institutional protocols to refer to the standardised vinblastine/prednisolone backbone for SS-multifocal and MS-LCH. Let me now compile the complete dosing for this specific patient.
LCH Single-System Multifocal (Nodal) — SHARE Protocol
Patient: 10 years | 33 kg | BSA 1.16 m²
Classification: SS-LCH, Multifocal (nodal) — Low-risk (no risk-organ involvement)
Protocol backbone: Vinblastine + Prednisolone (Histiocyte Society LCH-III/LCH-IV Stratum I, Group 2 equivalent; SHARE = standard frontline regimen for multifocal SS-LCH)
Total treatment duration: 12 months
Phase 1 — Initial Therapy (Induction)
Weeks 1–6 (6-week induction course)
| Drug | Dose | Calculation (BSA 1.16 m²) | Route | Schedule |
|---|---|---|---|---|
| Vinblastine | 6 mg/m² | 6.96 mg → round to 7 mg (max cap 10 mg) | IV bolus | Once weekly: Days 1, 8, 15, 22, 29, 36 |
| Prednisolone | 40 mg/m²/day | 46.4 mg/day → 45–46 mg/day (max cap 60 mg/day) | PO | Days 1–28 (full dose) |
| Prednisolone taper | Taper from day 29 | Reduce over 2 weeks (days 29–42) | PO | Stepwise taper to zero |
Note on vinblastine cap: Standard cap is 10 mg for patients ≥10 kg; at 6.96 mg this patient is well below the cap.
Phase 2 — Continuation Therapy (Weeks 7–52)
Pulses every 3 weeks from Day 43 onward, total duration to complete 12 months of treatment (~17–18 pulses).
| Drug | Dose | Calculation (BSA 1.16 m²) | Route | Schedule per pulse |
|---|---|---|---|---|
| Vinblastine | 6 mg/m² | 6.96 mg → 7 mg (max cap 10 mg) | IV bolus | Day 1 of each 3-week cycle |
| Prednisolone | 40 mg/m²/day | 46.4 mg/day → 45–46 mg/day (max cap 60 mg/day) | PO | Days 1–5 of each 3-week cycle |
Total continuation pulses: ~17 cycles (weeks 7 through 52, every 3 weeks).
Prophylaxis Medications
1. PCP (Pneumocystis jirovecii) Prophylaxis — TMP-SMX
| Drug | Dose | Calculation (33 kg) | Route | Schedule |
|---|---|---|---|---|
| Co-trimoxazole (TMP-SMX) | 5 mg/kg/dose TMP component | 5 × 33 = 165 mg TMP = ~150 mg TMP (use 1.5 × adult SS tab 80 mg TMP or paediatric suspension) | PO | 3 days/week (Mon–Wed–Fri) |
Practical dosing: Paediatric suspension (8 mg/mL TMP + 40 mg/mL SMX) — ~20 mL (160 mg TMP / 800 mg SMX) three times per week, OR adult single-strength tablet (80 mg TMP / 400 mg SMX) × 2 tablets three times per week.
Alternatively some centres use once-daily dosing at 5 mg/kg TMP on all 7 days; both regimens are acceptable.
Duration: Throughout all immunosuppressive chemotherapy and for 4–6 weeks after the last steroid/vinblastine dose.
2. Antifungal Prophylaxis
In the context of the SHARE / Histiocyte Society backbone (prednisolone at 40 mg/m² for prolonged courses), antifungal prophylaxis is not universally mandated for low-risk SS-multifocal LCH, but fluconazole is used by many centres during induction steroid courses.
| Drug | Dose | Calculation | Route | Schedule |
|---|---|---|---|---|
| Fluconazole (if instituted) | 3–6 mg/kg/day | 3.5–7 mg/kg → 99–116 mg → round to 100 mg/day (max 400 mg/day) | PO | Daily during steroid induction (Weeks 1–6); reassess in continuation |
Institution-specific; not universally required. Omit or use based on local policy and degree of immunosuppression.
3. Gastric Protection
| Drug | Dose | Calculation | Route | Schedule |
|---|---|---|---|---|
| Omeprazole (PPI) | 1 mg/kg/day (max 20–40 mg/day) | 33 mg → 20 mg/day (standard paediatric dose) | PO | During steroid courses |
4. Bone Protection (if prolonged steroid course)
| Agent | Dose | Notes |
|---|---|---|
| Calcium | 500–1000 mg/day elemental | Dietary + supplement |
| Vitamin D | 400–800 IU/day | Standard supplementation |
Summary Dosing Card for This Patient
| Drug | Per-dose (BSA 1.16 m²) | Frequency |
|---|---|---|
| Vinblastine | 7 mg IV | Weekly ×6 (induction), then Day 1 of every 3-week pulse (continuation) |
| Prednisolone | 46 mg PO | Daily ×28 days (induction) → taper weeks 5–6; then Days 1–5 of every 3-week pulse |
| Co-trimoxazole | 160 mg TMP / 800 mg SMX (2 × SS tabs or 20 mL susp.) | 3×/week (Mon/Wed/Fri) for duration of therapy |
| Omeprazole | 20 mg PO | Daily during steroid courses |
| Calcium + Vit D | 500–1000 mg + 400–800 IU | Daily throughout |
Response Assessment
| Time point | Assessment |
|---|---|
| Week 6 (end of induction) | Clinical exam, imaging of involved nodes — assess for Active Disease Better (ADB), Active Disease Stable (ADS), Active Disease Worse (ADW), or No Active Disease (NAD) |
| Week 12 | Re-evaluation — if ADW at week 6, escalate per institutional protocol |
| End of treatment (Month 12) | Full restaging |
Key Protocol Notes
- Nodal SS-multifocal LCH falls into LCH-IV Stratum I (Group 2) — same first-line regimen as multifocal bone SS-LCH.
- The 12-month total duration (vs. 6 months) is supported by LCH-III trial data showing superior reactivation-free survival with prolonged maintenance.
- Reactivation rate for multifocal SS-LCH is ~37%; this reinforces the value of the full 12-month course.
- Vinblastine dose modification: Reduce by 50% if direct bilirubin >3× ULN; hold if peripheral neuropathy grade ≥3.
- No dose modification for weight below 10 kg — this patient at 33 kg uses full BSA-based dosing.
- Mercaptopurine (6-MP, 50 mg/m² = ~58 mg/day) is added in some protocols (LCH-A1 adult, Donadieu LCH-S-2005 salvage), but is not standard in the Histiocyte Society frontline paediatric backbone for SS-multifocal disease outside of a clinical trial.
- The ESCP/SIOP standard practice document confirms this vinblastine/prednisolone backbone as current standard frontline therapy for multifocal SS and MS-LCH in children outside clinical trials.
Disclaimer: Drug doses should be verified against your institutional formulary and current protocol version before administration. Always confirm with the treating paediatric oncologist.
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