Log in to post a reply
Nov 26, 2020 12:16AM
So there aren't many interesting abstracts at SABCS so far (haven't read them all, plus the newsworthy ones are being embargoed till early Dec, so hope there are some good headlines this year)
However abstract 490 is interesting. They did a survey of how patients in the real world did on different secondline treatments, and here is bottom line:
Results: A total of 1,210 pts with HR+/Her2- mBC received CDK4/6i with ET in the frontline setting, including 29.1% with de novo metastatic disease. Average age at diagnosis of metastatic disease was 64.4 years (range 28-84). A majority of pts received palbociclib in the frontline setting (88.2%), and 68.8% received an aromatase inhibitor (AI) as the frontline ET partner. 839 pts subsequently received second-line therapy. CDK4/6i was continued as part of second-line treatment in 308 (36.7%) pts. 249 (29.7%) pts received Chemotherapy (CT) as second-line treatment. The proportion of pts who continued CDK4/6i increased from years 2015-2020 (p=0.035), and the proportion who received CT decreased over time (p<0.001). Of the 308 pts who received a CKD4/6i in the second-line setting, most received the same CDK4/6i in both lines;however, pts treated with abemaciclib or ribociclib in the first-line setting were more likely to receive a different CDK4/6i than those who started withpalbociclib (54.2% and 39.1%, respectively, vs. 22.3%).
Among 160 pts who received CDK4/6i with fulvestrant in the second-line setting, 81.2% had previously received an AI in the frontline setting. Unadjusted real world (rw) PFS appears to favor those pts who continued the CDK4/6i (rwPFS 11.27 months, 95%CI [8.87, 13.31]), compared to CT (rwPFS 4.73 months, 95% CI [3.88, 5.59]), fulvestrant (rwPFS 3.68 months, 95% CI [2.99, 5.22]),or mammalian target of rapamycin (mTOR) inhibitor-based therapy (rwPFS 4.27 months, 95% CI [3.23, 6.14]) (p<0.001).
Conclusion: The use of CDK4/6i continuation after frontline progression has increased over time, while the use of CT has decreased. Continuation of CDK4/6i in the second-line setting appears to be the strategy with the greatest PFS benefit.
So, it seems promising to move from AI to fulvestrant while keeping the CDK4,6 inhibitor as secondlineto get a PFS of 11.27 months (half will do better than that), and potentially those numbers might be higher for a SERD with CDK4,6 inhibitor, certainly would be for those with ESR1 mutations. Chemo or Piqray were similar in secondline, and barely better than Fulvestrant alone, and so again even a SERD alone might be comparable or better than chemo.
The ADC Enhertu or Trodelvy have a longer PFS than chemo, so they would fit in there somewhere in-between; might be a longer PFS than fulvestrant with CDK4,6 inhibitor, but still being chemo you'd probably want to be endocrine-resistant before moving to those
10/2003, IDC, Stage IIB, ER+/PR+, HER2-
7/2015, Stage IV, metastasized to bone, ER+/PR-, HER2-