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Results of the KELLY trial

Updated: Dec 7, 2022

Pembrolizumab plus eribulin in patients with previously treated, luminal metastatic breast cancer.

The KELLY study was one of the first MEDSIR-designed and MEDSIR-sponsored projects. Through an immunotherapy-based approach, this trial has the potential to establish a new treatment to patients with metastatic breast cancer (MBC). Today, we are very pleased to announce that the results of this study have just been published in the latest edition of European Journal of Cancer.

In the past decade, immunotherapies have revolutionized the way we treat cancer. By harnessing the innate powers of the body's immune system, immunotherapy can be used to help recognize and fight cancer cells in a less harmful way when compared to chemotherapy and radiation therapy, which in turn ameliorates the patients’ quality of life. Immunotherapy can be used in combination with standard treatments, increasing its overall effectiveness in deterring cancer growth, and therefore prolonging patient survival.

The KELLY trial is a good example of how MEDSIR seeks –in a very patient-focused manner– to find new niches for established drugs, in this case pembrolizumab and eribulin, to reach beyond their established indications. This study is aimed to evaluate the efficacy and safety of eribulin in combination with pembrolizumab in patients who have previously received an anthracycline and taxane treatment for hormone receptor-positive (HR+) / Human Epidermal Growth Factor Receptor 2-negative (HER2–), unresectable locally advanced or MBC.

Eribulin is a non-taxane microtubule dynamic inhibitor, approved as monotherapy for the treatment of patients with MBC who have previously received several lines of chemotherapeutic regimens. Whilst pembrolizumab is a type of immunotherapy known as a checkpoint inhibitor, which works by blocking the PD-1/PD-L1 receptor-ligand interaction, preventing cancer cells from escaping immune system detection. Pembrolizumab is approved in combination with chemotherapy for the treatment of patients with previously untreated metastatic triple-negative breast cancer.

In this multicenter, open-label, single-arm, phase II study, 44 patients were accrued from 11 sites in Spain and received intravenous administration of pembrolizumab (200 mg, on day 1) and eribulin (1.23mg/m2, on days 1 and 8) on each 21-day treatment cycle.

The primary objective aimed to assess the proportion of patients who achieved a clinical benefit from the combination. The KELLY study confirms that 25 patients out of 44 (56.8%; 95% confidence interval [CI]: 41.0–71.7) achieved a clinical benefit, meeting the primary objective of the study. Of the 44 patients enrolled, an objective response was reported in 18 patients (40.9%; 95% CI: 26.3–56.8), with a median progression-free survival of 6.0 months (95% CI: 3.7–8.4), with 1-year overall survival elevated by 59.1% (95% CI: 45.8–76.2).

The reported adverse events were in line with the overall safety profile of prior studies based on eribulin or pembrolizumab as single agents.

Results from KELLY, on the whole, showed a promising antitumoral activity accompanied by an acceptable safety profile in patients with heavily pretreated, HR+ / HER2– locally recurrent or MBC. A deeper investigation of patients’ characteristics and biomarkers will be key to determine the benefits of moving towards a larger comparative trial of combination therapy, and eventually demonstrate the efficacy in implementing this strategy in standard clinical routines.

To that aim, biospecimens from patients enrolled in KELLY are currently under evaluation in the sub-study CALADRIO. Here, through the analysis of microbiota composition in oral and fecal samples, we seek to identify microbial phylum distribution as a biomarker to identify the subclass of patients that can be predicted to respond better to pembrolizumab-based immunotherapy.

KELLY trial was designed and sponsored by MEDSIR and funded by Merck Sharp & Dohme (MSD) and EISAI Co., Ltd.



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