Practical considerations for application of IWG 2023 criteria for HR-MDS
| . | Recommendations for clinical practice . |
|---|---|
| Time window for response assessment and need for response confirmation | •Response assessment allows a window of 2 weeks either before or after the date of BM assessment to allow regeneration of blood counts without need for a repeat BM biopsy to confirm the response. Appropriate timing of response assessment is especially important in the setting of ongoing myelosuppressive therapy.•Cytopenias related to acute illness or induced by MDS therapy (ie, not due to the underlying MDS), will not be used to end duration of response.•Once response is achieved, this date should be used as the start of duration of response, without need for subsequent response confirmation. |
| Discrepancy between BM and PB blasts percentage | •There might be a discrepancy between <5% blasts in the BM and PB blasts being >0% at time of BM biopsy. In this case, repeat PB blast assessment within 2 weeks should be done to distinguish whether this elevation of PB blasts is disease related vs not (eg, seen in setting of marrow recovery, infection etc).•If within 2 weeks of the BM biopsy PB blasts clear (ie, are 0%) and BM biopsy showed <5% blasts, the patient will have achieved a CR without the need for a repeat BM biopsy for confirmation purposes. |
| Screening period and time window for on-trial assessment of HI and transfusion dependency/independence | •Screening period for the evaluation of transfusion burden and baseline Hb levels is ideally 16 weeks; however, given the acuity of HR-MDS an 8-week screening period before treatment initiation is acceptable.•For HI and TI assessments, a 16-week time window should be used.•Effects of transient myelosuppression on active treatment with hematologic recovery before the initiation of the next cycle is permissible. |
| Enumeration of blasts in blood and BM | •Blast percentages should optimally be derived by a manual count of 500 cells in the BM aspirate smear (or touch preparation) and 200 cells in the PB smear; in paucicellular samples, a blast count based on a smaller number of cells is acceptable, but a minimum of 100 cells should be counted. In the setting of disease relapse or PD and a hemodilute specimen, a lower cell count can be acceptable if numerous blasts are present.•In the instance of a paucicellular BM aspirate and touch prep or “dry tap,” an estimate of the blast count based on CD34 immunostaining of the BM biopsy may substitute for an aspirate blast count, particularly if the biopsy blast estimate is higher than that obtained from the aspirate or touch prep.•The blast percentage by flow cytometry usually correlates with the blast count obtained by morphology but should not be used in lieu of the morphologic blast count. |
| . | Recommendations for clinical practice . |
|---|---|
| Time window for response assessment and need for response confirmation | •Response assessment allows a window of 2 weeks either before or after the date of BM assessment to allow regeneration of blood counts without need for a repeat BM biopsy to confirm the response. Appropriate timing of response assessment is especially important in the setting of ongoing myelosuppressive therapy.•Cytopenias related to acute illness or induced by MDS therapy (ie, not due to the underlying MDS), will not be used to end duration of response.•Once response is achieved, this date should be used as the start of duration of response, without need for subsequent response confirmation. |
| Discrepancy between BM and PB blasts percentage | •There might be a discrepancy between <5% blasts in the BM and PB blasts being >0% at time of BM biopsy. In this case, repeat PB blast assessment within 2 weeks should be done to distinguish whether this elevation of PB blasts is disease related vs not (eg, seen in setting of marrow recovery, infection etc).•If within 2 weeks of the BM biopsy PB blasts clear (ie, are 0%) and BM biopsy showed <5% blasts, the patient will have achieved a CR without the need for a repeat BM biopsy for confirmation purposes. |
| Screening period and time window for on-trial assessment of HI and transfusion dependency/independence | •Screening period for the evaluation of transfusion burden and baseline Hb levels is ideally 16 weeks; however, given the acuity of HR-MDS an 8-week screening period before treatment initiation is acceptable.•For HI and TI assessments, a 16-week time window should be used.•Effects of transient myelosuppression on active treatment with hematologic recovery before the initiation of the next cycle is permissible. |
| Enumeration of blasts in blood and BM | •Blast percentages should optimally be derived by a manual count of 500 cells in the BM aspirate smear (or touch preparation) and 200 cells in the PB smear; in paucicellular samples, a blast count based on a smaller number of cells is acceptable, but a minimum of 100 cells should be counted. In the setting of disease relapse or PD and a hemodilute specimen, a lower cell count can be acceptable if numerous blasts are present.•In the instance of a paucicellular BM aspirate and touch prep or “dry tap,” an estimate of the blast count based on CD34 immunostaining of the BM biopsy may substitute for an aspirate blast count, particularly if the biopsy blast estimate is higher than that obtained from the aspirate or touch prep.•The blast percentage by flow cytometry usually correlates with the blast count obtained by morphology but should not be used in lieu of the morphologic blast count. |