Cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors plus endocrine therapy (ET) represents the standard first-line treatment for patients with hormone receptor–positive/human epidermal growth factor receptor 2–negative (HER2-negative) advanced breast cancer (ABC). However, there is no definitive consensus on the preferred second-line treatment option. The PALMIRA trial investigated whether palbociclib rechallenge with an alternative ET would improve the antitumor activity in patients progressing after a first-line palbociclib-containing regimen.
This international, randomized, open-label, phase II study enrolled 198 patients with hormone receptor–positive/HER2-negative ABC with disease progression after first-line palbociclib plus ET (aromatase inhibitor or fulvestrant). Patients were eligible if they showed clinical benefit to the previous regimen (response or stable disease ≥24 weeks) or had progressed on a palbociclib-based therapy in the adjuvant setting. Patients were randomly assigned (2:1 ratio) to either palbociclib rechallenge plus second-line ET (fulvestrant or letrozole) or second-line ET alone. Stratification factors were previous ET and visceral involvement. The primary end point was investigator-assessed progression-free survival (PFS).
Between April 2019 and October 2022, 136 and 62 patients were randomly assigned to palbociclib plus ET or ET alone, respectively. Median investigator-assessed PFS was 4.9 months (95% CI, 3.6 to 6.1) with palbociclib plus ET versus 3.6 months (95% CI, 2.5 to 4.2) with ET alone (hazard ratio, 0.84 [95% CI, 0.66 to 1.07]; P = .149). Grade ≥3 treatment-emergent adverse events were higher with palbociclib plus ET (47.4% v 10.0%), without new safety signals.
Palbociclib rechallenge plus an alternative ET did not significantly improve PFS compared with ET alone in patients with hormone receptor–positive/HER2-negative ABC progressing on a first-line palbociclib-based ET regimen.
Progression-free survival (PFS) was statistically significantly improved with addition of tucatinib versus placebo 24.9 v 16.3 months regardless of the presence/absence of BM or hormone receptor status.
1467 pts with RS > 25 and 551 with clinically (neoadjuvant cohort in ADAPT-HR+/HER2-) or pathologically N2, (longer) docetaxel-based CTx showed better distant, invasive disease-free survival in N2-3 pts patients with RS ≤25, OS was also shown in pts with RS>25 anthracycline regimens did not show a significant survival difference in high-risk HR+/HER2 whether used in neoadjuvant or adjuvant setting. So may be no anthracycline for HR+ve pts who are high risk disease.
Primary objective not met, ctDNA clearance post- neoadjuvant therapy (NAT) cannot reliably predict pathologic complete response (pCR) and shouldn't be used to defer surgery. But the prognostic data are striking: post-NAT ctDNA positivity independently predicted recurrence in triple-negative breast cancer (TNBC) (HR 8.9), and the postsurgical landmark analysis is essentially binary, 100% of ctDNA-positive patients recurred while 94% of ctDNA-negative patients were disease-free at 5 years (HR 128). Not practice-changing yet pending prospective utility trials, but this strongly validates ultrasensitive ctDNA as a prognostic tool and a smart enrollment biomarker for future escalation/de-escalation trials.
Gedatolisib potently targets all four class I PI3K isoforms and mTORC1 and mTORC2 to comprehensively block the PI3K/AKT/mTOR pathway. PFS was 9.3 m in the gedatolisib-triplet group vs 2.0 m in the fulvestrant group (hazard ratio) HR 0.24, and 7.4 m in the gedatolisib-doublet group HR 0.33 v fulvestrant.
This is impressive. However, there is no reported placebo trastuzumab deruxtecan arm, so this is not truly a “no chemotherapy” regimen. It is important to remember that deruxtecan is itself a chemotherapy agent. So, this is really comparing deruxtecan vs taxol or more accurately, a comparison of chemotherapy delivery systems.