iwCLL 2018International Workshop on CLL Standardized Assessment
Examination & Organ Response
Laboratory & Bone Marrow
Progression Alerts
Response Classification
Select the clinical and laboratory findings to determine the standardized iwCLL 2018 response category.
Guidelines & Evidence
Verified
Last Review: 2026
When to Use
What is iwCLL 2018?
The International Workshop on Chronic Lymphocytic Leukemia (iwCLL) published the updated 2018 guidelines to standardize response assessment in CLL clinical trials and clinical practice. These criteria replaced the 2008 (Hallek) and 1996 (Cheson) guidelines. The 2018 update reflects the paradigm shift from cytotoxic chemo-immunotherapy (FCR, BR, chlorambucil) to continuous targeted agents (BTK inhibitors: ibrutinib, acalabrutinib, zanubrutinib; BCL2 inhibitor: venetoclax; PI3K inhibitors: idelalisib, duvelisib) and fixed-duration combinations (venetoclax + obinutuzumab, ibrutinib + venetoclax). The criteria ensure global uniformity in clinical trial endpoints (ORR, CR rate, PFS, TTNT), which is critical for regulatory approval by FDA, EMA, and PMDA.
Primary Clinical Applications
Clinical trials endpoint assessment (phase 1-3) - primary endpoint often ORR (CR + PR) for single-arm trials, PFS for randomized trials
Individual patient management: determining response to therapy, timing of next-line treatment, and switching from ineffective regimens
Regulatory approval: FDA and EMA require iwCLL-defined response categories for CLL drug approvals
Comparative effectiveness research: allows pooling of data across trials and real-world cohorts using standardized definitions
Minimal residual disease (MRD) assessment integration: 2018 update incorporated MRD as a secondary endpoint
Richter transformation surveillance: new rapid symptomatic lymphadenopathy triggers biopsy
Key 2018 Updates vs 2008 Criteria
| Parameter | 2008 iwCLL Criteria | 2018 iwCLL Criteria | Clinical Rationale |
|---|---|---|---|
| Lymph node threshold for PR | ≥ 50% decrease from baseline | Same - ≥ 50% decrease | Remains robust predictor of response |
| CT imaging requirement for CR | Mandatory CT chest/abdomen/pelvis | Mandatory CT chest/abdomen/pelvis (same) | Detects mesenteric, retroperitoneal, or mediastinal nodes not palpable |
| CR with incomplete marrow recovery (CRi) | Allowed (PLT <100 or Hgb <11 if other CR criteria met) | Same - CRi retained | Distinguishes response from treatment-related myelosuppression vs residual CLL |
| MRD assessment | Not incorporated | Added as secondary endpoint (flow cytometry or PCR, threshold 10⁻⁴) | MRD negativity predicts longer PFS, especially with venetoclax |
| Richter Transformation definition | Mentioned but not formalized | Explicit definition with PET-CT SUVmax >5-10; biopsy required | Early detection enables aggressive therapy |
| Nodular Partial Response (nPR) | Bone marrow nodules but no CLL in blood/imaging | nPR retained | Distinguishes from CR when marrow shows lymphoid aggregates |
Related Scores in Practice
In clinical practice, this assessment is frequently evaluated alongside other validated measures. Depending on the patient's presentation and specific diagnostic requirements, you may also need to utilize the CLL-IPI, MRD Assessment Threshold Interpreter or the CTCAE v5.0 to formulate a comprehensive care plan.
Last Comprehensive Review: 2026