P14.76 Bevacizumab (BEV) alone or in combination with chemotherapy in recurrent Glioblastoma Multiforme (GBM): A real world experience

BACKGROUND

Patients with glioblastoma multiforme (GBM) have a median survival of about 14 months. In recurrent GBM no active intervention has shown improvement in survival. Clinical trials has shown that bevacizumab (BEV) alone or in combination with chemotherapy is associated with better progression free survival (PFS). The current study aims to assess efficacy of BEV in real-world setting.

MATERIAL AND METHODS

Population-based retrospective cohort study patients with recurrent GBM diagnosed in the province of Saskatchewan during 2008–2018 and received BEV alone or in combination with chemotherapy were evaluated. Survival was compared with historic control.

RESULTS

43 eligible patients with GBM treated with BEV with or without chemotherapy. 25 patients were treated with Bev alone and 18 patients treated with chemotherapy+ BEV. Median age of the patients were noted to be 53 years. 28 male, and 15 female. 80% of patients treated with single agent BEV had a performance status of either 2 or 3 compared to 33% of patient treated with BEV+ chemotherapy.

Median PFS was 4.6 months with 95% CI 2.9–6.9. Median Overall survival (OS) from the time of diagnosis was 17.5 month. Median OS from the time of start of BEV was 5.4 months with 95% CI 3.4–6.8. Partial response (PR) was noted in 3 patients (7%) with stable disease (SD) in 6 patients (14%). 33 (77%) had progressive disease (PD). We were unable to confirm response status in one patient (2%). No statistically significant difference in response rate for patients treated with BEV and BEV+ Chemotherapy. From the start of Bev to the best response, 11 patients (30.56%) noted decrease in the dose of steroids, 14 patients (38.89%) dose remained unchanged. 7 patients (19.44%) required increase in the dose of steroids. 4 patients (11.11%) were not on steroids. For 7 patients we did not have the information on use of steroids. PFS was better for patients treated with chemotherapy + BEV with median PFS of 6.9 months, 95% CI 3.2- 22.3 verses BEV alone with median PFS 3.53 months 95% CI 1.4–5.3, P-value 0.0449. The Cox regression model for PFS to test comparing Bev with chemotherapy vs. Bev alone with the co-variables of sex, age, and ECOG performance status (PS). The model showed that patient with higher ECOG PS were noted to have inferior PFS with a Hazard ratio of 1.92 95% CI 1.09–3.37. P value of 0.2. Patient treated with BEV+ chemo had better PFS with a HR of 6.44 95% CI 1.86–22.28. P value of 0.003.

CONCLUSION

Retrospective real world study confirms that, patients with recurrent GBM, treatment with BEV is associated with similar PFS as reported in literature. Our study showed similar overall survival from the diagnosis compared to historic control. However the Median OS from Start of BEV was noted to be inferior to what is reported in EORTC EH1.3. Better ECOG performance status is associated with better PFS. Higher number of patients with ECOG 2 and 3 received BEV alone.