Hematologic safety in patients treated with Radium - 223 in Fundación Santa Fe de Bogota, Colombia , between 2014 - 2017

Objectives: To evaluate the hematologic safety of radium-223 by describing hematologic variables evolution and hematologic adverse events in CRPC (Castration Resistant Prostate Cancer) patients treated at our oncologic center between January 2014 and January 2017. Materials and Methods. We retrospectively reviewed 37 patients (147 doses) with metastatic castration resistant prostate cancer treated with radium-223. Radium-223 was given at a dose of 55 kBq/kg every 4 weeks for up to 6 cycles. Patient demographics, clinical variables and hematologic laboratory values (hemoglobin level, neutrophil and platelet count, before each dose administration) were collected from medical records and analyzed. Results. The median age was 72 years (interquartile range, 52-69). The mean number of cycles administered per patient was 3.97 (SD: 2.0). Thirteen patients (35.14%) received all 6 scheduled cycles; 7 received 5 doses, 2 received 4 doses, 3 received 3 doses, 5 received 2 doses and 7 received 1 dose, for a total of 147 doses. The baseline median values of hemoglobin level, neutrophil and platelet counts were 13.1 g/dl (11.8-14.2 g/dl), 4073 /mm³ (3240- 5000 /mm³) and 239,000 /mm³ (190,000 - 333,500 /mm³), respectively; during follow-up, the lowest median value for hemoglobin level, neutrophil and platelet counts were 12.2 g/dl (10.8-13.1 g/dl), 2400 /mm³ (1730 - 3190 /mm³) and 210,000 /mm³ (161,000 - 257,000 /mm³), respectively, observed after 4^th (hemoglobin and ANC) an 5^th (platelet count) dose administration. For the 13 patients who received all 6 cycles, the baseline median values of hemoglobin level, neutrophil and platelet counts were 13.6 g/dl (13-14.4 g/dl), 3700 /mm³ (3180 - 4766 /mm³) and 293,000 /mm³ (203,000 - 362,500 /mm³), respectively; the lowest median value for hemoglobin level, neutrophil and platelet counts were 12.8 g/dl (11.5-13.9 g/dl), 2380 /mm³ (1730 - 3190 /mm³) and 281,000 /mm³ (141,500 - 364,500 /mm³), respectively, observed after 4th dose administration. Seventeen (47.22%), one (2.78%) and two (5.56%) patients presented anemia, neutropenia and thrombocytopenia grade 1-2 (CTCAE criteria) respectively, before initiation of treatment. Twenty six (70.27%), ten (27.78%) and three (11.11%) patients reported anemia, neutropenia and thrombocytopenia, respectively, during treatment (after 1^st, 2^nd, 3^rd, 4^th and 5^th doses). After 4^th cycle administration, 68.42%, 36.84 and 11.11% of 20 patients presented anemia, neutropenia and thrombocytopenia, the highest rates of these adverse events during the 6-cycles treatment. No events of anemia, neutropenia, febrile neutropenia or thrombocytopenia grade 3-4 were reported during treatment. No events of anemia, neutropenia or febrile neutropenia grade 3-4 were reported during treatment. During treatment, no patient required blood transfusions. Conclusion. Radium-223 has a favorable hematologic safety profile in treatment of CRPC patients with a low incidence of hematologic adverse events. However, it is recommended to monitor and verify hematologic parameters periodically during drug administration.