Esmo 2019 – Abbvie’s Parp underwhelms in breast cancer

An underwhelming performance in breast cancer has added to a flat Esmo congress for Abbvie’s Parp inhibitor veliparib. The Brocade-3 trial tested the project in combination with chemo in second-line, Her2-negative, BRCA-positive patients with advanced disease, generating less than two months' survival advantage versus chemo. The result was statistically significant, but Abbvie might struggle to argue its clinical relevance, particularly as the overall response rate was largely the same in both arms. No impact on overall survival was seen – although no Parp inhibitor has shown this in this tumour type. Abbvie will probably point to signs of a durable benefit – 26% patients on the veliparib arm were alive and progression-free at three years versus 11% of the control group – and a seemingly stronger PFS result by independent reviewers. Parps are only approved third line in this tumour type, but it is unclear whether the company will file on these data, or on the ovarian cancer results unveiled yesterday, neither of which would afford velaparib a position of strength in an extremely competitive market. Abbvie does not seem to be sponsoring any active veliparib trials, which probably speaks volumes.

Parps in BRCA-mutated, Her2-negative metastatic breast cancer
  Veliparib: Brocade-3     
  2nd line, n=337     
  Veliparib plus chemo  Placebo plus chemo    
mPFS per INV  14.5 months 12.6 months    
   Hazard ratio 0.71 (p=0.002)    
mPFS per IRC  19.3 months 13.5 months    
   Hazard ratio 0.70 (no p value available)    
mOS 33.5 months 28.2 months    
   Hazard ratio 0.95 (p=0.67)    
ORR  75.80% 74.10%    
INV=investigator; IRC=independent review committee. Source: Esmo 2019 congress.
 
Approved Parps in this tumour type 
  Lynparza: Olympiad Talzenna: Embraca
  3rd line, n=302  3rd line, n=431 
  Lynparza Chemo Talzenna Chemo
mPFS 7 months 4.2 months 8.6 months 5.6 months
   Hazard ratio 0.58 (p=000.9) 0.54 (p<0.0001)
mOS  19.3 months 17.1 months 22.3 months 19.5 months
   Hazard ratio 0.9 (not stat sig) 0.76 (p=0.11)*
ORR  52% 23% 50.2% 18.4%
*Interim OS, as per NEJM, not on drug label. All other data from FDA drug labels. 

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