Hematopoiesis is prognostic for toxicity and survival of 223 Radium treatment in patients with metastatic castration-resistant prostate cancer.

OBJECTIVE: We evaluated the impact of pre-therapeutic hematopoiesis on survival, hematotoxicity (HT) and number of 223 Radium (223 Ra) treatments in patients with metastatic castration-resistant prostate cancer.

SUBJECTS AND METHOD: Hemoglobin-levels (Hb), the number of platelets (Plts), leukocytes (Leuk), and survival data were collected in 56 patients treated with 223 Ra. Pre-therapeutic hematopoiesis as well as adverse events during and after therapy were scored (grade 0-4) according to the CTCAE recommendations. The association of pre-therapeutic hematopoiesis, survival, HT and numbers of 223 Ra cycles was analyzed.

RESULTS: Median survival in all patients was 69.9 weeks; 77% of patients had pre-existing impaired Hb (1.7% grade 3, 12.5% grade 2, 62.5% grade 1). 8/56 (14.3%) had impaired Plt (grade 1) Maximum toxicity (Tox) grades of patients during treatment were grade 4 (Hb 1.7%; Plt 1.7%), grade 3 (Hb 14.3%; Plt 7.1%; Leu 7.1%), grade 2 (Hb 33.9%; Plt 7.1%; Leu 23.2%), grade 1 (Hb 46.4%; Plt 17.9%; Leu 23.2%) and grade 0 (Hb 5.4%; Plt 66.1%; Leu 44.6%). Interestingly, patients with thrombocytopenia had a significantly shorter survival compared to those with normal Plt levels (21 weeks vs not reached; P<0.003). As expected patients with pre-therapeutic low Hb-level (<10g/dL) had a significantly shorter survival compared to those with Hb-level >10g/dL (28 weeks vs not reached, P<0.004), whereas survival of patients with mildly impaired Hb (>10 but <13.5g/dL) did not differ from patients with normal levels of Hb (X vs. Y, P=...). Also patients with impaired Hb also developed significantly more grade 3 and 4 HT (Hb <10g/dL: 42.9 vs 14.3%, P<0.001; Plt <150G/mL: 25.0% vs 6.3%; P=0.002) and received significantly fewer treatment cycles (Hb<10g/dL: 5.1 vs 5.8, P<0.04; Plt <150G/mL: 3.4 vs 5.6; P<0.001). Neither extent of bone metastases nor previous chemotherapy were associated with survival, number of 223 Ra cycles and HT.

CONCLUSION: Patients with metastatic castration-resistant prostate cancer and impaired hematopoiesis, in particular thrombocytopenia and anemia, before 223 Ra therapy suffer from significantly more high-grade HT, shorter survival and receive significantly fewer 223 Ra treatments. Therefore, Hb-levels and platelet counts are essential parameters for adequate patient selection for 223 Ra therapy.