Medical College of Wisconsin, Milwaukee, WI
Michael Pierro , Ariel Ann Nelson , John Xie , Albert Jang , Kathryn A. Bylow , Pedro C. Barata , Colleen Anne Lawton , Deepak Kilari
Background: Radium-223 (Ra-223), a targeted alpha-emitting radiopharmaceutical approved for the treatment of metastatic prostate cancer (mPC), can cause myelosuppression. In the ALSYMPCA trial 30% of patients developed cytopenias, including 13% with grade 3/4 anemia. Therefore, it is recommended that only men with a hemoglobin ≥10 g/dL, platelet count ≥100,000/mm3, and ANC ≥1,500/mm3 be considered for Ra-223. Since the FDA approval of Ra-223 in 2013, several new treatments have been approved for men with mPC. With the changing therapeutic landscape, we anticipate more patients (pts) will have preexisting cytopenia prior to Ra-223 consideration. Hence, clinicians are increasingly likely to face the dilemma of whether it is safe and efficacious to administer Ra-223 in the setting of Hgb ≤10 with/without RBC transfusion support. Methods: We retrospectively identified pts with mPC treated with Ra-223, including a subset of men with Hgb <10g/dl at the Medical College of Wisconsin and Tulane Cancer Center from 2014 – 2019. Clinical data including demographics, prior cancer treatments, laboratory data, blood product transfusion data, and oncologic outcomes were collected. Survival was estimated using Kaplan-Meier method and statistical analysis was conducted using student’s t-test. Results: Sixty-two pts were identified. Median age at the time of Ra-223 was 75.3 years. Of these, nearly 20% (n=12) had a Hgb <10 g/dL and/or received RBC transfusions to meet “eligibility criteria” prior to beginning Ra-223 treatments. Compared to men who had Hgb >10g/dL, men with Hgb <10g/dL required more RBC transfusions both during and after Ra-223 treatment and had significantly worse oncologic outcomes. No patients experienced treatment delays of more than 1 week. There were no significant differences in the median number of treatments prior to Ra-223, median number of Ra-223 treatments received, platelet count nadir, or ANC nadir. Conclusions: Pre-existing Hgb < 10 g/dl and/or RBC transfusions prior to Ra-223 therapy is associated with worse oncologic outcomes in mPC, suggesting that the benefit of Ra-223 is limited in this subset. A larger sample size is needed to further validate our findings. Multivariable analysis is planned.
Hgb <10 or Transfused | Hgb >10 | p-value | |
---|---|---|---|
Median OS, months (95% CI) | 5.9 (3.2 - 10.7) | 12.2 (7.7 - 15.8) | p=0.021 |
Median PFS, months (95% CI) | 3.1 (1.7 - 4.4) | 6.6 (4.8 - 8.5) | p=0.017 |
Median Number of Treatments Prior to Ra-223 | 3.5 | 4 | p=0.741 |
Median PSA at Ra-223 Start | 63.4 | 27.1 | p=0.057 |
Median Number of Ra-223 Treatments | 3 | 5 | p=0.200 |
RBC Transfusion During Ra-223 | 33.3% | 10% | p=0.040 |
RBC Transfusion after Ra-223 | 50% | 21.6% | p=0.046 |
ANC Nadir During Ra-223 (x103/mm3) | 4.2 | 3.9 | p=0.686 |
Hgb Nadir During Ra-223 (g/dL) | 8.1 | 10.1 | p=0.001 |
Plt Nadir During Ra-223 (x103/mm3) | 120.4 | 135.2 | p=0.529 |
OS: Overall survival; PFS: progression-free survival; ANC: absolute neutrophil count.
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