Schurmans, Céline

PURPOSE BMI affects breast cancer risk and prognosis. In contrast to cytotoxic chemotherapy, CDK4/6 inhibitors are given at a fixed dose, irrespective of BMI or weight. This preplanned analysis of the global randomized PALLAS trial investigates the impact of BMI on the side-effect profile, treatment adherence, and efficacy of palbociclib. METHODS Patients were categorized at baseline according to WHO BMI categories. Neutropenia rates were assessed with univariable and multivariable logistic regression. Time to early discontinuation of palbociclib was analyzed with Fine and Gray competing risk models. Unstratified Cox models were used to investigate the association between BMI category and time to invasive disease-free survival (iDFS). 95% CIs were derived. RESULTS Of 5,698 patients included in this analysis, 68 (1.2%) were underweight, 2,082 (36.5%) normal weight, 1,818 (31.9%) overweight, and 1,730 (30.4%) obese at baseline. In the palbociclib arm, higher BMI was associated with a significant decrease in neutropenia (unadjusted odds ratio for 1-unit change, 0.93; 95% CI, 0.91 to 0.94; adjusted for age, race ethnicity, region, chemotherapy use, and Eastern Cooperative Oncology Group at baseline, 0.93; 95% CI, 0.92 to 0.95). This translated into a significant decrease in treatment discontinuation rate with higher BMI (adjusted hazard ratio [HR] for 10-unit change, 0.75; 95% CI, 0.67 to 0.83). There was no significant improvement in iDFS with the addition of palbociclib to ET in any weight category (normal weight HR, 0.84; 95% CI, 0.63 to 1.12; overweight HR, 1.10; 95% CI, 0.82 to 1.49; and obese HR, 0.95; 95% CI, 0.69 to 1.30) in this analysis early in follow-up (31 months). CONCLUSION This preplanned analysis of the PALLAS trial demonstrates a significant impact of BMI on side effects, dose reductions, early treatment discontinuation, and relative dose intensity. Additional long-term follow-up will further evaluate whether BMI ultimately affects outcome.

518 Background: Body Mass Index (BMI) impacts breast cancer risk and prognosis. Conflicting results have been published regarding BMI as a predictive factor for endocrine therapy benefit. CDK4/6 inhibitors (CDK4/6i) in combination with endocrine treatment (ET) are standard-of-care treatments for metastatic hormone receptor-positive breast cancer. In contrast to cytotoxic chemotherapy, CDK4/6i are given at a fixed dose irrespective of BMI or weight. The PALLAS trial compared the combination of the CDK4/6i palbociclib and adjuvant ET to ET alone in the early breast cancer setting. This analysis investigates the impact of BMI on the efficacy and the side effect profile of palbociclib (P) in the PALLAS trial. Methods: In this pre-planned analysis, patients (pts) enrolled in PALLAS were categorized according to BMI as underweight (BMI <18.5 kg/m2), normal weight (BMI 18.5-24.9 kg/m2), overweight (BMI 25-29.9 kg/m2) and obese (³30 kg/m2), respectively. Adverse event differences were assessed with Chi-squared tests. Time to early discontinuation of P was analyzed with Fine and Gray competing risk models. Cox models were used to investigate the association between BMI category and time to invasive disease-free survival (iDFS). Results: Of a total of 5698 pts included in this analysis, 68 (1.2%) were underweight, 2082 (36.5%) normal weight, 1818 (31.9%) overweight and 1730 (30.4%) obese at baseline. Significantly different rates of all grade neutropenia were observed in normal weight, overweight and obese pts with regard to total (88.5%, 85.7% and 74.7%), as well as grade 3 (64.1%, 62.0% and 43.9%) and grade 4 neutropenia (7.0%, 3.6% and 2.0%), respectively. The lower frequency and severity of neutropenia observed in overweight and obese pts was associated with a significant lower treatment discontinuation rate over time when compared to normal weight patients (overweight vs normal weight: HR 0.73 CI 0.63-0.84, p<0.0001, and obese vs normal weight: HR 0.65 CI 0.56-0.75, p<0.0001). In pts treated with P, neutropenia was the primary toxicity leading to treatment discontinuation in 21.1% of normal weight pts, 14.0% of overweight pts and 5.9% obese pts, respectively. Despite these observations, there was no statistically significant improvement in iDFS with the addition of P to ET in any weight category (normal weight HR 0.84 CI 0.63-1.12, overweight HR 1.10 CI 0.82-1.49 and obese HR 0.95 CI 0.69-1.30). Conclusions: This pre-planned analysis of outcomes by BMI in the PALLAS trial demonstrates significantly less frequent and less severe neutropenia in overweight and obese pts compared to those with normal weight, leading to significant lower treatment discontinuation rates. However, no difference in iDFS outcomes by BMI was observed. Additional long-term follow-up will further evaluate whether BMI ultimately impacts outcome. Clinical trial information: NCT02513394.

Abstract Background Advances in the multidisciplinary care of hormone-receptor positive (HR+) early breast cancer (eBC) have markedly improved clinical outcomes: however, disease recurrence may still occur, particularly in patients (pts) with moderate or high-risk cancers at the time of diagnosis. The use of CDK4/6 inhibitors (CDK4/6i) combined with endocrine therapy (ET) is a standard of care for advanced breast cancer, supporting the rationale to study CDK4/6i in the eBC setting. Here we present the final protocol-planned analyses of the global phase III PALLAS trial investigating whether the addition of the CDK4/6i palbociclib (P) to adjuvant ET improves outcomes over ET alone for HR+/HER2- eBC. Methods PALLAS (PALbociclib CoLlaborative Adjuvant Study, NCT02513394) is a randomized phase III open-label trial in which pts with stage II-III HR+/HER2- eBC were randomized to receive either 2 years of P with adjuvant ET (P+ET) or ET alone. The primary endpoint is invasive disease-free survival (iDFS); secondary endpoints include distant recurrence-free survival (DRFS), locoregional recurrence-free survival (LRRFS), overall survival (OS), and safety. Mandatory biospecimen collection has supported the creation of an expansive translational science program, and long-term follow-up is planned. Revised sample size calculations required recruitment of 5600 pts in order to detect a 25% iDFS improvement in patients receiving P+ET with 85% power; this final protocol-planned analysis was planned after 469 iDFS events. Results From September 1, 2015 to November 30, 2018, 5,761 pts (median age 52 years, range 22-90) were randomized in 406 centers in 21 countries worldwide. 1,014 (17.6%) had stage IIA disease (capped) and 4,728 (82.1%) stages IIB/III. 4,754 (82.5%) had received prior (neo)adjuvant chemotherapy. After a protocol-planned 2nd interim analysis in May 2020 crossed the futility threshold, 349 P+ET pts still on active treatment stopped P and were transferred to follow-up. At the time of final analysis cutoff date (November 20, 2020), after a median follow-up of 31 months and 516 events recorded, iDFS was similar between the two arms, with 3-year iDFS of 89.3% (95% CI: 87.8-90.6%) for Palbo+ET, and 89.4% (88.0-90.7%) for ET alone (hazard ratio 0.96, 95% CI: 0.81-1.14). There was no statistically significant difference in secondary outcome endpoints. Subgroup analyses revealed no significant interactions between treatment effect and other factors (including risk category). The safety profile of P was as expected, with grade 3 or 4 neutropenia the most common side effect (safety population: 1759/2841 [61.9%] vs 11/2902 [0.4%]). Overall 42% of pts. discontinued P prior to the planned 2-year duration, 28.2% of Palbo+ET pts discontinued therapy due to adverse events, without an observed impact on survival outcomes. Conclusions Now with the full number of events, this analysis of the PALLAS trial shows that the addition of 2 years of P to ongoing adjuvant ET did not improve survival endpoints for pts with stage II-III HR+/HER2- eBC. Whether P is beneficial in the adjuvant setting for certain sub-groups of pts will be further evaluated with longer-term follow-up and by the ongoing translational science program. Support: ABCSG; AFT; Pfizer; ClinicalTrials.gov Identifier: NCT02513394; https://www.abcsg.org; https://acknowledgments.alliancefound.org Citation Format: Michael Gnant, Amylou C Dueck, Sophie Frantal, Miguel Martin, Hal Burstein, Richard Greil, Peter Fox, Antonio C Wolff, Arlene Chan, Eric Winer, Christian Singer, Kathy Miller, Marco Colleoni, Michelle Naughton, Gabor Rubovszky, Judith Bliss, Ingrid A Mayer, Guenther G Steger, Zbigniew Nowecki, Olwen Hahn, Norman Wolmark, Hope Rugo, Georg Pfeiler, Hannes Fohler, Otto Metzger, Céline Schurmans, Kathy P Theall, Dongrui R Lu, Kathleen Tenner, Christian Fesl, Angela DeMichele*, Erica L Mayer, *shared last authorship. Adjuvant palbociclib in HR+/HER2- early breast cancer: Final results from 5,760 patients in the randomized phase III PALLAS trial [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr GS1-07.

PURPOSE Palbociclib is a cyclin-dependent kinase 4 and 6 inhibitor approved for advanced breast cancer. In the adjuvant setting, the potential value of adding palbociclib to endocrine therapy for hormone receptor–positive breast cancer has not been confirmed. PATIENTS AND METHODS In the prospective, randomized, phase III PALLAS trial, patients with hormone receptor–positive, human epidermal growth factor receptor 2–negative early breast cancer were randomly assigned to receive 2 years of palbociclib (125 mg orally once daily, days 1-21 of a 28-day cycle) with adjuvant endocrine therapy or adjuvant endocrine therapy alone (for at least 5 years). The primary end point of the study was invasive disease-free survival (iDFS); secondary end points were invasive breast cancer–free survival, distant recurrence-free survival, locoregional cancer-free survival, and overall survival. RESULTS Among 5,796 patients enrolled at 406 centers in 21 countries worldwide over 3 years, 5,761 were included in the intention-to-treat population. At the final protocol-defined analysis, at a median follow-up of 31 months, iDFS events occurred in 253 of 2,884 (8.8%) patients who received palbociclib plus endocrine therapy and in 263 of 2,877 (9.1%) patients who received endocrine therapy alone, with similar results between the two treatment groups (iDFS at 4 years: 84.2% v 84.5%; hazard ratio, 0.96; CI, 0.81 to 1.14; P = .65). No significant differences were observed for secondary time-to-event end points, and subgroup analyses did not show any differences by subgroup. There were no new safety signals for palbociclib in this trial. CONCLUSION At this final analysis of the PALLAS trial, the addition of adjuvant palbociclib to standard endocrine therapy did not improve outcomes over endocrine therapy alone in patients with early hormone receptor–positive breast cancer.