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Breast cancer, metastatic

1498 - Duration of response and tumor shrinkage with first-line ribociclib + letrozole in postmenopausal women with HR+, HER2– ABC

Date

10 Sep 2017

Session

Breast cancer, metastatic

Topics

Cytotoxic Therapy;  Breast Cancer

Presenters

Wolfgang Janni

Citation

Annals of Oncology (2017) 28 (suppl_5): v74-v108. 10.1093/annonc/mdx365

Authors

W. Janni1, E. Alba Conejo2, T. Bachelot3, S. Diab4, M. Gil5, T.J. Beck6, L. Ryvo7, R. López8, M. Tsai9, F.J. Esteva10, M.P. Zamora Aunon11, Z. Kral12, P. Ward13, P. Richards14, T.J. Pluard15, S. Sutradhar16, M. Miller16, M. Campone17

Author affiliations

  • 1 Department Of Gynecology And Obstetrics, Ulm Medical University, 89081 - Ulm/DE
  • 2 Clinical Oncology, Hospital Universitario Virgen de la Victoria, 29010 - Malaga/ES
  • 3 Medical Oncology, Centre Léon Bérard, 69008 - Lyon/FR
  • 4 Medical Oncology, Rocky Mountain Cancer Center, Aurora/CA
  • 5 Medical Oncology, Institut Català d'Oncologia, L'Hospitalet de Llobregat, 08907 - Barcelona/ES
  • 6 Medical Oncology, Highlands Oncology Group, Fayetteville/US
  • 7 Oncology, Tel Aviv Sourasky Medical Center, 64239 - Tel Aviv/IL
  • 8 Medical Oncology Department, Hospital Clínico de Santiago, Santiago de Compostela/ES
  • 9 Medical Oncology, Minnesota Oncology, Minneapolis/US
  • 10 Medical Oncology, New York University Langone Medical Center, 10016 - New York/US
  • 11 Medical Oncology, Hospital Universitario La Paz, 28046 - Madrid/ES
  • 12 Hematology And Oncology, The University Hospital Brno, Brno/CZ
  • 13 Oncology Hematology Care, Medical Oncology, Kenwood/US
  • 14 Medical Oncology, Oncology Hematology Associates of Southwest Virginia, Salem/US
  • 15 Medical Oncology, Saint Luke’s Health System, Kansas City/US
  • 16 Oncology, Novartis Pharmaceuticals Corporation, 07936-1080 - East Hanover/US
  • 17 Medical Oncology, ICO Institut de Cancerologie de l'Ouest René Gauducheau, 44805 - Saint-Herblain/FR
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Resources

Abstract 1498

Background

The Phase 3 MONALEESA-2 study (NCT01958021) demonstrated that addition of ribociclib (RIB; cyclin-dependent kinase 4/6 inhibitor) to letrozole (LET) significantly improved progression-free survival (PFS) in patients (pts) with hormone receptor-positive (HR+), HER2-negative (HER2–) advanced breast cancer (ABC). RIB benefit was observed as early as 8 weeks. Here we evaluate duration of response (DoR) and tumor shrinkage.

Methods

Postmenopausal women (N = 668) with HR+, HER2– ABC and no prior systemic therapy for ABC were randomized to RIB (600 mg/day; 3 weeks on/1 week off) + LET (2.5 mg/day; continuous) or placebo (PBO) + LET. Pts had measurable disease or ≥ 1 predominantly lytic bone lesion. Primary endpoint was PFS; DoR was an exploratory endpoint. Tumor assessments were conducted every 8 weeks for the first 18 months. For tumor shrinkage analyses, pts were grouped by quartiles (Q) for best % change in target lesion; pts were excluded from this analysis if best % change was unavailable or contradicted by overall response of unknown/progressive disease.

Results

Of 501 pts with measurable disease, 135 (53%) vs 91 (37%) pts had a complete response or partial response in the RIB + LET vs PBO + LET arm, respectively. At a median follow-up of 15.3 months, median DoR was not reached in either arm. Tumor shrinkage was evaluable in 443 (66%) pts. Pt characteristics were well-balanced in both arms and irrespective of tumor shrinkage, apart from de novo ABC in Q2–Q3 (RIB + LET vs PBO + LET; 46% vs 30%) and visceral disease in ≤Q1 (64% vs 84%). A higher proportion of pts in the RIB + LET vs PBO + LET arm experienced a best % change of at least 53% (Table). In all evaluable pts, mean % change in tumor size was greater in the RIB + LET vs PBO + LET arm at each tumor evaluation over the first 18 months.Table:

245PD

QCut-offCorresponding best % change in tumor sizeRIB + LET n=231PBO + LET n = 212
≤Q1≤25%At least –53%73 (32%)38 (18%)
Q1–Q2>25% to ≤ 50%Between –53% and –33%64 (28%)52 (25%)
Q2–Q3>50% to ≤ 75%Between –33% and –12%52 (23%)54 (25%)
>Q3>75%Less than –12%42 (18%)68 (32%)

Conclusions

In postmenopausal women with HR+, HER2– ABC, first-line RIB + LET prolonged PFS and was associated with a greater degree of tumor shrinkage vs PBO + LET.

Clinical trial identification

NCT01958021

Legal entity responsible for the study

Novartis Pharmaceuticals Corporation

Funding

Novartis Pharmaceuticals Corporation

Disclosure

W. Janni: Research grants and/or honoraria from Sanofi-Aventis, Novartis, Roche, Pfizer, AstraZeneca, Chugai, GSK, Eisai, Cellgene, Johnson & Johnson. T. Bachelot: Research funding from Roche and Novartis; Consultant for AstraZeneca, Roche, Novartis, and Pfizer; travel from AstraZeneca, Roche, Novartis, Pfizer. F.J. Esteva: Research funds and consultancy/honoraria from Novartis. T.J. Pluard: Advisor for Novartis. S. Sutradhar: Novartis employee. M. Miller: Novartis employee and Novartis stocks/shares. M. Campone: Consultant/advisory role for Novartis, Pfizer, AstraZeneca, Roche, and Lilly. All other authors have declared no conflicts of interest.

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