Palbociclib combined with endocrine therapy in heavily pretreated HR+/HER2- advanced breast cancer patients: Results from the compassionate use program in Spain (PALBOCOMP)

Background

This study evaluated efficacy and safety of palbociclib, a CDK4/6 inhibitor, in heavily-pretreated hormone receptor-positive and human epidermal growth factor receptor 2-negative (HR⁺/HER2^-) metastatic breast cancer (mBC) patients during the compassionate use program in Spain from February 2015 to November 2017.

Patients and methods

Patient data were collected retrospectively from 35 hospitals in Spain. Patients with HR⁺/HER2^- mBC who had progressed on ≥4 treatments for advanced disease were eligible.

Results

A total of 219 patients received palbociclib in combination with aromatase inhibitors (110; 50.2%), fulvestrant (87; 39.7%), tamoxifen (8; 3.6%) or as single agent (10; 4.6%). Mean age of the patients was 58 years; 31 patients (16.1%) were premenopausal and 162 (83.9%) were postmenopausal at the beginning of treatment with palbociclib. Patients had received a median of 3 previous lines of endocrine therapy (ET) for advanced disease. Real-world tumor response (rwTR) and clinical benefit rate were 5.9% (n = 13) and 46.2% (n = 101), respectively. The median real world progression-free survival (rwPFS) was 6.0 months (95% CI 5.7–7.0) and the median overall survival was 19.0 months (95% CI 16.4–21.7). Subgroup analysis revealed a significant difference in median rwPFS in patients treated with palbociclib plus fulvestrant depending on the duration of prior treatment with fulvestrant monotherapy (>6 versus ≤6 months; HR 1.93, 95% CI 1.37–2.73, p < 0.001). The most frequently reported toxicities were neutropenia, asthenia, thrombopenia and anemia.

Conclusions

Palbociclib can be an effective and safe treatment option in patients with heavily pretreated endocrine-sensitive mBC, especially in those with longer PFS to previous ET.

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CDK4/6 inhibitors combined with endocrine therapy have been widely accepted as a new standard therapy for hormone receptor-positive metastatic breast cancer patients in first or second line.

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Palbociclib alone or in combination with aromatase inhibitors, fulvestrant, or tamoxifen was effective and safe in heavily pretreated HR⁺/HER2^- metastatic breast cancer patients.

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Palbociclib could be of higher benefit to patients with endocrine-sensitive disease that had a long duration of response to previous endocrine therapy.

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Real-world evidence of effectiveness and safety of use of palbociclib in heavily pretreated advanced breast cancer patients complements data from randomized clinical trials.

Specific humoral response in cancer patients treated with a VEGF-specific active immunotherapy procedure within a compassionate use program

BACKGROUND

CIGB-247 is a cancer therapeutic vaccine that uses as antigen a variant of human vascular endothelial growth factor (VEGF) mixed with the bacterially-derived adjuvant VSSP. CIGB-247 has been already evaluated in two phase I clinical trials (CENTAURO and CENTAURO-2), showing to be safe and immunogenic in advanced cancer patients selected under well-defined and controlled clinical conditions. Surviving patients were submitted to monthly re-immunizations and some of them showed objective clinical benefits. Based on these results, a compassionate use program (CUP) with CIGB-247 was initiated for patients that did not meet the strict entry criteria applied for the CENTAURO and CENTAURO-2 clinical trials, but could potentially benefit from the application of this cancer therapeutic vaccine.

RESULTS

Polyclonal IgM, IgA and IgG antibodies specific for VEGF were detected by ELISA in serum samples from patients vaccinated with 400 μg of antigen combined with 200 μg of VSSP. Polyclonal antibody response showed no cross reactivity for other VEGF family member molecules like VEGF-C and VEGF-D. Serum from immunized individuals was able to block the binding of VEGF to its receptors VEGFR2 and VEGFR1. IgG fraction purified from immune sera shared the aforementioned characteristics and also inhibited the interaction between VEGF and the therapeutic recombinant antibody bevacizumab, an anti-angiogenic drug approved for the treatment of different tumors. No serious adverse events attributable to CIGB-247 have been documented yet in participants of the CIGB-247 CUP. The present paper is a first report of our findings concerning the humoral response and safety characteristics in treated CIGB-247 CUP cancer patients. The study has provided the unique opportunity of not only testing CIGB-247 in a broader clinical spectrum sample of Cuban cancer patients, but also within the context of the day-to-day clinical practice and treatment settings for these diseases in Cuban medical institutions.

CONCLUSIONS

The CIGB-247 CUP has demonstrated that immunization and follow-up of a variety of cancer patients, under day-to-day clinical practice conditions in several Cuban medical institutions, replicate our previous findings in clinical trials: CIGB-247 is safe and immunogenic.

Palbociclib in highly pretreated metastatic ER-positive HER2-negative breast cancer

PURPOSE

We aimed to investigate the role of palbociclib, a first-in-class cyclin-dependent kinase 4 and 6 inhibitor, in postmenopausal women with highly pretreated endocrine therapy-resistant metastatic breast cancer (MBC).

METHODS

Between 28 September 2015 and 14 March 2017, a compassionate use program was established in the University Hospitals Leuven in which 82 postmenopausal women with estrogen receptor-positive, HER2-negative MBC were included after at least four lines of systemic treatment. The efficacy and safety analysis was performed in 82 patients who had received at least one dose of palbociclib and who had at least 6-month follow-up at the data cut-off point. The primary objective was the evaluation of efficacy of the combination of palbociclib and endocrine therapy with clinical benefit as primary endpoint, defined as the absence of progressive disease and being on treatment for at least 6 months. Secondary objectives were the evaluation of toxicity and the identification of potential predictors for clinical benefit.

RESULTS

The median age of the patients was 67.1 years (range 34.8-85.9) at the time of inclusion. The average duration of treatment was 5.6 months (range 1-19), with a median progression-free survival of 3.17 (95% CI 2.76-4.70) months. At the data cut-off point, 10 patients were still on treatment with palbociclib. In this highly pretreated setting, 34 patients experienced no progressive disease within 6 months, resulting in an overall clinical benefit rate (CBR) of 41.5%. 20.7% (17/82) showed stable disease for ≥ 9 months and 13.4% for ≥ 12 months. None of the investigated predicting factors were significantly associated with clinical benefit at 6 months. For 43.9% of the patients, treatment delay or dose reduction was indicated.

CONCLUSIONS

Palbociclib in combination with endocrine therapy shows an unexpectedly high CBR and favorable safety profile in heavily pretreated endocrine-resistant estrogen receptor-positive, HER2-negative MBC patients.