Outcomes of Immunotherapy (ICI) Alone vs. Stereotactic Radiosurgery (SRS) Alone vs. ICI and SRS Combined in Melanoma Brain Metastasis

• Published in: International journal of radiation oncology, biology, physics Vol. 111; no. 3; pp. e575 - e576
• Main Authors: O'Shea, P.J., Tatineni, V., Rauf, Y., Jia, X., Murphy, E.S., Chao, S.T., Suh, J.H., Peereboom, D., Ahluwalia, M.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01-11-2021
• ISSN: 0360-3016; 1879-355X
• DOI: 10.1016/j.ijrobp.2021.07.1550

Melanoma is the third most common cause of metastatic brain tumors. Both Immune Checkpoint Inhibitors (ICIs) and Stereotactic Radiosurgery (SRS) have been used as first line treatment for melanoma brain metastasis (MBM). The efficacy of ICIs alone, SRS alone, or SRS and ICIs combined as treatment is being evaluated. We hypothesize that a combination of SRS and ICIs will lead to an improvement in Overall Survival (OS), when compared to either alone, for patients with MBM.
Patients with MBM treated at our tertiary care center (2010-2020) with either ICIs, SRS, or both were evaluated. OS was measured from initiation of immunotherapy or SRS of MBM to date of death or last follow up. The Cox proportional hazard model was used to determine differences in OS.
368 patients with MBM were included. Of these, 62 were treated with ICIs alone, 151 were treated with SRS alone, and 155 were treated with a combination of ICIs and SRS. For treatment with ICIs alone, the median age at diagnosis was 61 years (Interquartile range (IQR) 26-89), 70% of the patients were male, and 97% were white. For treatment with SRS alone the median age at diagnosis was 59 years (IQR 24-88), 58% of the patients were male, and 100% were white. For ICIs/SRS combination treatment, the median age at diagnosis was 63 years (IQR 23-87), 65% of the patients were male, and 98% were white. Overall Survival for patients treated with ICIs alone, SRS alone, and ICIs/SRS combined had a median of 24.2, 14.5, and 56.1 months and a 2 year rate of 50%, 35%, and 72%, respectively. With ICI treatment alone as a reference, SRS treatment alone had an OS hazard ratio, HR = 1.34 (95% CI = 0.96 – 1.89, P = 0.088), and ICI/SRS combination treatment had an OS hazard ratio, HR = 0.57 (95% CI = 0.40 – 0.81, P = 0.002).
In patients with MBM, treatment with both ICIs and SRS was associated with an increase in Overall Survival when compared to treatment with either ICIs alone or SRS alone. Further studies need to be done to control for other patient variables such as KPS/ECOG, number of lesions, and extra-cranial metastasis.