PALBOCICLIB REAL WORLD DATA IN ADVANCED AND METASTATIC BREAST CANCER TREATED: A MULTICENTER EXPERIENCE IN LEBANON

treated with palbociclib + ET in second and third lines (28.5% and 30.5%, respectively). Other pts received palbociclib in ≥4th lines. In 24,8% pts (26/105) palbociclib was combined with aromatase inhibitors, in other cases – with fulvestrant. Median follow-up time was 6.5 months (1.1–31.9), median progression free survival – 6.0 months (1.0–28.0). The median follow-up time is a limitation for adequate assessment of median PFS and comparison with RCT and available RCP results. Sixty-five pts continued palbociclib at the time of analysis. Most common adverse events (AE) were leukopenia, neutropenia and thrombocytopenia. Dose reduction due to toxicity was required in 10 from 73 pts (in other pts there is no toxicity data). Only in 3 cases palbociclib was completely stopped due to toxicity.
Conclusions: In this analysis of RCP in wide pts population palbociclib in combination with ET was initiated mainly in postmenopausal pts with primary and secondary endocrine resistance. Majority of pts had visceral mts. Palbociclib was used mainly in 2+ lines with fulvestrant. No new signs of toxicity were observed. This data indicates that there is a need to move palbociclib initiation in first two lines of treatment to get maximal improvement in survival and to increase its usage in young women. More detailed analysis is planned.
Acknowledgement: Supported by investigational grant of Pfizer Russia

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UPDATE SURVIVAL OF PHASE 1B CLINICAL TRIAL OF HX008, A NOVEL ANTI-PD-1 MONOCLONAL ANTIBODY, COMBINED WITH GEMCITABINE AND CISPLATIN IN THE FIRST-LINE TREATMENT OF METASTATIC TRIPLE-NEGATIVE BREAST CANCER
Jun Cao, Xichun Hu, Biyun Wang, Jian Zhang, Leiping Wang, Zhonghua Tao, Ting Li
Fudan University Shanghai Cancer Center, Shanghai, China
Background: HX008 is a humanized IgG4S228P anti-PD-1 monoclonal antibody with an engineered Fc domain. Gemcitabine plus cisplatin (GP) has shown satisfying antitumor activity as firstline therapy for metastatic triple-negative breast cancer (mTNBC) in CBCSG 006 trial (ClinicalTrials.gov, NCT01287624). The phase 1b study was conducted to assess the safety and preliminary antitumor activity of HX008, combined with GP in patients with mTNBC in first-line setting.
Methods: Eligible patients are mTNBC with ≥6 months DFI who never receive antitumor therapy for metastatic disease. Participants received HX008 at 3 mg/kg (d1, q3w) plus gemcitabine at 1250 mg/m2 (d1, 8, q3w) and cisplatin 75 mg/m2 (d1, q3w). At most 6 cycles of GP chemotherapy were given, while HX 008 could be maintained until disease progression or unacceptable toxicity occurred.
Results: Between July 2019 and March 2020, a total of 31 patients were enrolled in this study. Median (range) age was 50 (29– 69) years. Among 31 patients who were evaluated, 25 (80.6%) experienced objective response and the other 6 (19.4%) experienced stable disease (SD). As of June 10, the latest median progression free survival (PFS) was 9.0 months (95% CI 7.29–15.08m). The most common treatment-related adverse events of grade 3 or 4 included neutropenia (71.0%), anemia (55.5%), thrombocytopenia (32.3%), hypocalcemia (9.68%), hypokalemia (6.45%), and alanine aminotransferase increased (6.45%). There were no treatmentrelated deaths.
Conclusion: HX008 plus GP demonstrated promising activity and manageable safety in patients with mTNBC in first-line setting. Exploring analysis of PAM50 subtype is being done.
Clinical trial information: CHINADRUGTRIALS.ORG, CTR 20191353.

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PALBOCICLIB REAL WORLD DATA IN ADVANCED AND METASTATIC BREAST CANCER TREATED: A MULTICENTER EXPERIENCE IN LEBANON
Fadi Nasr¹ ² ³, Saada Diab¹, Ahmad Al Ghoche¹, Intissar Yehia¹,Lewis Nasr²
¹Department of Hematology-Oncology, Mount Lebanon university Hospital, Balamand University Beirut, Lebanon; ²Department of Hematology-Oncology, Hotel-Dieu de France University Hospital, Faculty of Medicine, Saint Joseph University, Beirut, Lebanon; ³ Notre Dame de Secours University Hospital, Faculty of Medicine, Université Saint Esprit Kaslik, Jounieh, Lebanon
Introduction: Approximately 70% of all breast cancer cases are hormone receptor (HR) positive. One of the most important treatment strategies for HR positive, human epidermal growth factor receptor 2 (HER2) negative subtype was endocrine treatment monotherapy by targeting estrogen receptor or aromatization and thus reducing estrogen level. However, resistance to this treatment and disease progression is universal. In the past few years, palbociclib, an oral inhibitor of cyclin dependent kinase 4 and 6 have been approved by the FDA, as a new standard of care in the metastatic or locally advanced setting either as front-line therapy or after progression. The aim of our study is to describe the real-world experience with palbociclib.
Method: Eligible patients had histologically confirmed metastatic breast cancer estrogen and progesterone receptors positive and HER2 receptor negative. Palbociclib was given 125 mg orally for 21 consecutive days of a cycle of 28 days. Patients were followed over three years. Primary objective was progression free survival (PFS). Overall response (OS) was defined as second objective.
Results: From 2018 to 2021, we identified a total of 95 breast cancer patients. All patients were females. The median age at diagnosis was 55 years. Among all the patients, 35% had visceral metastasis, 37% had non-visceral metastasis and 28% had the two types of metastases. 62% were de novo metastatic. 80.2% had less than 3 sites of metastasis. 50% of the study patients had received chemotherapy and endocrine therapy combined during treatment course, and 10% had only received prior adjuvant endocrine therapy. 26.36% took only prior systemic therapy for breast cancer. By the cutoff date for the final analysis (1/6/2021), a total of 22 events of disease progression occurred, and 25 death events happened. The median progression free survival was 30.26± 2.34 months for palbociclib combined with aromatase inhibitors as first line. OS was 9.67±0.6 years.
Conclusion: No real-world data were published before on palbociclib in Lebanon. We are the first to describe these characteristics. Our result (PFS 30.26±2.34 months)) is higher than the PFS obtain with PALOMA-2 (24 months).

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