Contributions
Abstract: PB1832
Type: Publication Only
Background
The detection of extremely small clone (<0.01%) became possible through high-sensitive flow cytometry (FCM), but the clinical significance of small PNH clone has not been elucidated.
Aims
To investigate a correlation of PIGA mutation and small PNH FCM clone, we measured PNH FCM clone size and mutant burden of PIG gene, with their correlation to treatment response.
Methods
A total of 89 specimens from 63 patients whose PNH clone size was ≥0.1% by FCM was enrolled (classic PNH 9, PNH related with bone marrow disorder 47, subclinical PNH 10). To detect minor cell population with PIG mutation, we adopted ultra-deep sequencing for PIGA, PIGM, PIGX and PIGT mutation.
Results
Twenty two % of 63 patients with PNH FCM clone harbored PIG gene mutation and 92.8% of patients with PIG mutation had >10% PNH FCM clone in RBC and granulocyte. In classic PNH patients (n=6), the average of PNH FCM clone size was 56.8% in RBC and 89.6% in granulocyte, and all patients had PIG gene mutation. In patients with subclinical PNH clone, the average of PNH FCM clone was 1.8% in RBC and 3.3% in granulocyte, while PIG gene mutation was not detected. In the patients with coexisting bone marrow disorder (BMD), the average of PNH FCM clone size was 8.0% in RBC and 14.9% in granulocyte. Among 6 patients with Eculizumab treatment, hemoglobin increment and decrease of FCM RBC clone size correlated, while LDH decreased in all patients, irrespective of treatment response. Decrease of the ratio over 0.15 (type III/type II+III PNH clone in RBC) was a predictive factor for complete response at 6 months from treatment initiation. Of the 11 patients with consecutive results of PIG mutation, 88% of patients with PIG mutations was non-responsive to supportive treatment, while 33% of patients without PIG mutations was non-response (p=0.072). Mutant burden of PIG gene mutation were not changed during treatment irrespective of types of treatment.
Conclusion
The PIG gene mutation was detected only in patients with >10% FCM PNH clone and The mutation burden of PIG gene was related to the granulocyte FCM PNH clone size. The presence of PIG gene mutations was correlated with adverse treatment response. We suggest monitoring of PNH clone in RBC can be a potential predictor of treatment response as well as Hb during treatment with Eculizumab.
Session topic: 12. Bone marrow failure syndromes incl. PNH - Clinical
Keyword(s): flow cytometry, Monoclonal antibody, Paroxysmal nocturnal hemoglobinuria (PNH)
Abstract: PB1832
Type: Publication Only
Background
The detection of extremely small clone (<0.01%) became possible through high-sensitive flow cytometry (FCM), but the clinical significance of small PNH clone has not been elucidated.
Aims
To investigate a correlation of PIGA mutation and small PNH FCM clone, we measured PNH FCM clone size and mutant burden of PIG gene, with their correlation to treatment response.
Methods
A total of 89 specimens from 63 patients whose PNH clone size was ≥0.1% by FCM was enrolled (classic PNH 9, PNH related with bone marrow disorder 47, subclinical PNH 10). To detect minor cell population with PIG mutation, we adopted ultra-deep sequencing for PIGA, PIGM, PIGX and PIGT mutation.
Results
Twenty two % of 63 patients with PNH FCM clone harbored PIG gene mutation and 92.8% of patients with PIG mutation had >10% PNH FCM clone in RBC and granulocyte. In classic PNH patients (n=6), the average of PNH FCM clone size was 56.8% in RBC and 89.6% in granulocyte, and all patients had PIG gene mutation. In patients with subclinical PNH clone, the average of PNH FCM clone was 1.8% in RBC and 3.3% in granulocyte, while PIG gene mutation was not detected. In the patients with coexisting bone marrow disorder (BMD), the average of PNH FCM clone size was 8.0% in RBC and 14.9% in granulocyte. Among 6 patients with Eculizumab treatment, hemoglobin increment and decrease of FCM RBC clone size correlated, while LDH decreased in all patients, irrespective of treatment response. Decrease of the ratio over 0.15 (type III/type II+III PNH clone in RBC) was a predictive factor for complete response at 6 months from treatment initiation. Of the 11 patients with consecutive results of PIG mutation, 88% of patients with PIG mutations was non-responsive to supportive treatment, while 33% of patients without PIG mutations was non-response (p=0.072). Mutant burden of PIG gene mutation were not changed during treatment irrespective of types of treatment.
Conclusion
The PIG gene mutation was detected only in patients with >10% FCM PNH clone and The mutation burden of PIG gene was related to the granulocyte FCM PNH clone size. The presence of PIG gene mutations was correlated with adverse treatment response. We suggest monitoring of PNH clone in RBC can be a potential predictor of treatment response as well as Hb during treatment with Eculizumab.
Session topic: 12. Bone marrow failure syndromes incl. PNH - Clinical
Keyword(s): flow cytometry, Monoclonal antibody, Paroxysmal nocturnal hemoglobinuria (PNH)