Antitumor activity of lurbinectedin in combination with oral capecitabine in patients with metastatic breast cancer

BACKGROUND

Preclinical studies showed a synergistic effect for 5-fluorouracil and lurbinectedin against solid tumors. This phase I trial evaluated a combination of capecitabine plus lurbinectedin in patients with selected advanced solid tumors. Results in patients with relapsed metastatic breast cancer (MBC) are described.

PATIENTS AND METHODS

Patients received capecitabine daily on day (D)1-D14 combined with lurbinectedin on D1, D8 or D1 every 3 weeks (q3w) intravenously, following a standard 3 + 3 escalation design and expansion at the recommended dose (RD).

RESULTS

Of the 81 enrolled patients, 28 had relapsed MBC: 20 with hormone receptor (HR)-positive tumors and 8 with triple-negative tumors; 3 treated in the D1,D8 schedule and 25 in the D1 schedule. The RD was capecitabine 1650 mg/m² daily on D1-D14 plus lurbinectedin 2.2 mg/m² on D1 q3w. Sixteen confirmed responses and two prolonged disease stabilizations (≥6 months) were observed [overall response rate (ORR)/clinical benefit rate (CBR) = 57%/64% at all dose levels; 47%/60% at the RD]. Twelve responses and both prolonged stabilizations occurred in HR-positive tumors (ORR/CBR = 60%/70% at all dose levels, 56%/78% at the RD). Four responses were found in triple-negative tumors (ORR and CBR = 50% at all dose levels; 33% at the RD). Myelotoxicity was reversible and manageable at the RD; most non-hematological toxicities were mild/moderate. No episodes of febrile neutropenia or severe palmar-plantar erythrodysesthesia syndrome occurred. No major pharmacokinetic drug-drug interaction was found between lurbinectedin, capecitabine or capecitabine metabolites.

CONCLUSIONS

The capecitabine/lurbinectedin combination showed encouraging clinical activity in relapsed MBC, especially in HR-positive tumors. Toxicity was manageable at the RD. Further development is warranted in relapsed MBC.

Antitumor activity of lurbinectedin (PM01183) and doxorubicin in relapsed small-cell lung cancer: results from a phase I study

BACKGROUND

Lurbinectedin (PM01183) has synergistic antitumor activity when combined with doxorubicin in mice with xenografted tumors. This phase I trial determined the recommended dose (RD) of doxorubicin (bolus) and PM01183 (1-h intravenous infusion) on day 1 every 3 weeks (q3wk), and obtained preliminary evidence of antitumor activity for this combination in small-cell lung cancer (SCLC).

PATIENTS AND METHODS

Patients with advanced solid tumors received doxorubicin and PM01183 following a standard dose escalation design and expansion at the RD. Twenty-seven patients had relapsed SCLC: 12 with sensitive disease (platinum-free interval ≥90 days) and 15 with resistant disease (platinum-free interval <90 days).

RESULTS

Doxorubicin 50 mg/m2 and PM01183 4.0 mg flat dose was the RD. In relapsed SCLC, treatment tolerance at the RD was manageable. Transient and reversible myelosuppression (including neutropenia, thrombocytopenia, and febrile neutropenia) was the main toxicity, managed with dose adjustment and colony-stimulating factors. Fatigue (79%), nausea/vomiting (58%), decreased appetite (53%), mucositis (53%), alopecia (42%), diarrhea/constipation (42%), and asymptomatic creatinine (68%) and transaminase increases (alanine aminotransferase 42%; aspartate aminotransferase 32%) were common, and mostly mild or moderate. Complete (n = 2, 8%) and partial response (n = 13, 50%) occurred in relapsed SCLC, mostly at the RD. Response rates at second line were 91.7% in sensitive disease [median progression-free survival (PFS)=5.8 months] and 33.3% in resistant disease (median PFS = 3.5 months). At third line, response rate was 20.0% (median PFS = 1.2 months), all in resistant disease.

CONCLUSION

Doxorubicin 50 mg/m2 and PM01183 4.0 mg flat dose on day 1 q3wk has shown remarkable activity, mainly in second line, with manageable tolerance in relapsed SCLC, leading to further evaluation of this combination within an ongoing phase III trial.

Kinetic modelling of the intestinal transport of sarafloxacin. Studies in situ in rat and in vitro in Caco-2 cells

The absorption kinetics of sarafloxacin, as a model of fluoroquinolone structure, were studied in the rat small intestine and in Caco-2 cells. The objective of the study was to investigate the mechanistic basis of the drug's intestinal transport in comparison with other members of the fluoroquinolone family and to apply a mathematical modelling approach to the transport process. In the rat small intestine, sarafloxacin showed dual mechanisms of intestinal absorption with a passive diffusional component and an absorptive carrier-mediated component. The characteristics of the animal study design made it suitable for population analysis, thus allowing the accurate estimation of transport parameters and their inter and intra-individual variances. The transport system in the rat model was ATP-dependent, as sodium azide was able to decrease the absorption rate constant in a concentration-dependent fashion. The inhibition mechanism of sodium azide was modelled based on its ATP depletion capacity. The rationale of this approach was to consider the inhibitor-carrier interaction as a concentration- dependent response. This interaction was accurately described by a non-competitive mechanism. In Caco-2 cells, sarafloxacin showed a concentration dependent permeability in both directions apical to basal, and basal to apical. The permeability values and ratios of permeability values at different concentrations suggested the presence of two carriers (absorption and efflux carriers). The passive diffusion component in both systems was compared to that predicted by the absorption-partition correlation, previously established for two series of fluoroquinolones. The discrepancy between the experimental and predicted value suggested the presence of an efflux mechanism similar to that already described for other fluoroquinolones. The differences and similarities of the in situ and the in vitro results are discussed as well as the usefulness of the modelling approach.