Abstract P2-14-18: Caelyx® as adjuvant treatment in early stage luminal B breast cancer: A feasibility phase II trial

Background Adjuvant chemotherapy regimens for ‘Luminal B’ disease usually include anthracycline-based regimens with or without taxanes. However, several patients are reluctant to receive chemotherapy because of toxic side-effects, especially alopecia, and ask for a “less intensive” or personalized approach. Methods We conducted a single-center, phase II, single-arm, feasibility study to evaluate pegylated liposomal doxorubicin (PLD, Caelyx®) as an adjuvant chemotherapy regimen in patients with early-stage luminal B breast cancer (BC). The primary endpoint was to evaluate the feasibility of this regimen, defined as the ability of a patient to achieve a relative dose intensity (RDI) of at least 85% of the 8 cycles of treatment (defined as a success). Under the assumption that a proportion of success less than 65% indicates an unfeasible regimen, a two-stage design involving 63 patients was used in order to allow early termination of the trial. Eighty percent was considered the smallest proportion of success suggesting that the regimen is feasible. Secondary endpoints included adverse events (AEs), tolerability, disease free survival (DFS) and overall survival (OS). Patients had operable histologically confirmed BC (pT1-3; any nodal status), Luminal B (ER positive, and at least one of the following: Ki-67 ≥20% or PgR ‘negative or low’) any HER2 status, candidate to adjuvant chemotherapy and endocrine therapy. Caelyx® was administered intravenously at 20 mg/m2 once every two weeks for 8 courses. Endocrine therapy was given according to menopausal status. Trastuzumab (Herceptin®) was administered in Luminal B HER2-positive disease for 12 months. Radiotherapy was given according to institutional accepted guidelines. Results From March 2016 to July 2018, 63 patients were included: median age 49 years (range: 33-76), mostly pre-perimenopausal (65%) and with stage I-II (94%). Only 5% of the patients had HER2 positive BC. Caelyx® median planned dose was 32 mg (range: 25-38; IQR: 30-34). Caelyx median actual dose was 31 mg (range: 0-38; IQR: 29-33). Caelyx® median RDI was 100% (range: 12.5%-100%; IQR: 87.5%-100%). The proportion of patients achieving success was 84% (95% CI: 73%-92%). AEs were mainly G2 (51%); 8 patients had G3 AEs (13%). None of the patients had alopecia. Overall, 55 out of 63 enrolled patients completed treatment (87%, 95% CI: 77%-94%), 4 patients did not receive the last cycle because of toxicity, 1 had cardiac toxicity, 2 had skin rash, 1 had a post-surgery complication. After a median follow-up of 2.3 years (range: 0.8-2.9) only 1 distant event was observed (bone lesions at 21 months from the end of Caelyx®). All patients with valid follow-up (n=60) were alive at the date of last visit. Conclusion The trial successfully met its primary endpoint, was feasible and well tolerated and could be considered as a treatment option for patients with contraindications to anthracyclines or asking for a less intensive approach. Citation Format: Silvia Dellapasqua, Vincenzo Bagnardi, Giuseppe Cancello, Claudia Sangalli, Eleonora Pagan, Manuelita Mazza, Monica Iorfida, Emilia Montagna, Anna Cardillo, Angela Sciandivasci, Nadia Bianco, Ana Paula De Maio, Monica Milano, Giuseppe Campenni, Loredana Sansonno, Mara Negri, Elisabetta Munzone. Caelyx® as adjuvant treatment in early stage luminal B breast cancer: A feasibility phase II trial [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-14-18.