Harnessing engineered antibodies of the IgE class to combat malignancy: initial assessment of FcɛRI-mediated basophil activation by a tumour-specific IgE antibody to evaluate the risk of type I hypersensitivity

BACKGROUND

IgE antibodies, sequestered into tissues and retained locally by the high-affinity IgE receptor, FcɛRI, on powerful effector cells such as mast cells, macrophages and eosinophils, may offer improvements in the therapy of solid tumours. The chimeric antibody, MOv18 IgE, against the human ovarian carcinoma antigen, folate receptor α (FRα), is more effective than its IgG1 counterpart in xenograft models of ovarian cancer. Although MOv18 IgE binds to a single epitope on FRα and cannot cross-link IgE receptors on basophils, there remains a risk that components in the circulation of ovarian cancer patients might cross-link FRα-MOv18-IgE-receptor-FcɛRI complexes on basophils to cause type I hypersensitivity.

OBJECTIVE

To assess the propensity for MOv18 used in a therapeutic setting to cause FcɛRI-mediated type I hypersensitivity.

METHODS

As validated readouts of the potential for MOv18 to cause FcɛRI-mediated type I hypersensitivity we measured release of a granule-stored mediator from a rat basophilic leukaemia cell line RBL SX-38 stably transfected with human tetrameric (αβγ2) FcɛRI, and induction of CD63 on blood basophils from patients with ovarian carcinoma and healthy controls ex vivo.

RESULTS

Serum FRα levels were increased in ovarian cancer patients compared with healthy controls. MOv18 IgE alone, or in the presence of its antigen recombinant human FRα, or of healthy volunteer (n=14) or ovarian carcinoma patient (n=32) sera, did not induce RBL SX-38 cell degranulation. Exposure to FRα-expressing ovarian tumour cells at target-to-effector ratios expected within tumours induced degranulation. MOv18 IgE did not induce expression of CD63 in blood basophils from either healthy volunteers (n=6), or cancer patients, despite detectable levels of circulating FRα (n=5).

CONCLUSION AND CLINICAL RELEVANCE

These encouraging data are compatible with the hypothesis that, when ovarian carcinoma patients are treated with MOv18, FcɛRI-mediated activation of effector cells occurs within the tumour mass but not in the circulation mandating, with due caution, further pre-clinical studies.

Trabectedin plus pegylated liposomal doxorubicin in relapsed ovarian cancer delays third-line chemotherapy and prolongs the platinum-free interval

BACKGROUND

OVA-301 is a large randomized trial that showed superiority of trabectedin plus pegylated liposomal doxorubicin (PLD; CentoCor Ortho Biotech Products L.P., Raritan, NJ, USA). over single-agent PLD in 672 patients with relapsed ovarian cancer, particularly in the partially platinum-sensitive subgroup [platinum-free interval (PFI) of 6-12 months]. This superiority has been suggested to be due to the differential impact of subsequent (platinum) therapy.

PATIENTS AND METHODS

a detailed analysis of subsequent therapies and survival outcomes in the overall population and in the subsets according to platinum sensitivity was therefore conducted.

RESULTS

similar proportions of patients received subsequent therapy in each arm (76% versus 77%), including further platinum-based regimens (49% versus 55%). Patients in the trabectedin/PLD arm received subsequent chemotherapy at a later time (median delay 2.5 months versus PLD arm). Overall survival from subsequent platinum was significantly prolonged in the partially platinum-sensitive disease subset (hazard ratio = 0.63; P = 0.0357).

CONCLUSION

the superiority of trabectedin/PLD over single-agent PLD in OVA-301 cannot be explained by differences in the extent or nature of subsequent therapies administered to these patients. On the other hand, these exploratory analyses support the hypothesis that the enhanced survival benefits in the partially platinum-sensitive subset might be due to an extended PFI leading to longer survival with subsequent platinum.

Trabectedin plus pegylated liposomal doxorubicin in relapsed ovarian cancer: outcomes in the partially platinum-sensitive (platinum-free interval 6-12 months) subpopulation of OVA-301 phase III randomized trial

BACKGROUND

OVA-301 is a large randomized trial that showed superiority of trabectedin plus pegylated liposomal doxorubicin (PLD) over PLD alone in relapsed ovarian cancer. The optimal management of patients with partially platinum-sensitive relapse [6-12 months platinum-free interval (PFI)] is unclear.

PATIENTS AND METHODS

within OVA-301, we therefore now report on the outcomes for the 214 cases in this subgroup.

RESULTS

Trabectedin/PLD resulted in a 35% risk reduction of disease progression (DP) or death [hazard ratio (HR) = 0.65, 95% confidence interval (CI), 0.45-0.92; P = 0.0152; median progression-free survival (PFS) 7.4 versus 5.5 months], and a significant 41% decrease in the risk of death (HR = 0.59; 95% CI, 0.43-0.82; P = 0.0015; median survival 23.0 versus 17.1 months). The safety of trabectedin/PLD in this subset mimicked that of the overall population. Similar proportions of patients received subsequent therapy in each arm (76% versus 77%), although patients in the trabectedin/PLD arm had a slightly lower proportion of further platinum (49% versus 55%). Importantly, patients in the trabectedin/PLD arm survived significantly longer after subsequent platinum (HR = 0.63; P = 0.0357; median 13.3 versus 9.8 months).

CONCLUSION

This hypothesis-generating analysis demonstrates that superior benefits with trabectedin/PLD in terms of PFS and survival in the overall population appear particularly enhanced in patients with partially sensitive disease (PFI 6-12 months).

A retrospective analysis of clinical outcome of patients with chemo-refractory metastatic breast cancer treated in a single institution phase I unit

BACKGROUND AND METHODS

Novel approaches to treat chemo-refractory metastatic breast cancer (MBC) are currently under investigation. This retrospective series reviews the outcome of 70 MBC patients who have participated in 30 phase I trials at the Royal Marsden Hospital from 2002 to 2009.

RESULTS

The median treatment lines before phase I trial entry for MBC was 5 (range: 1-12 lines). The overall response rate was 11.4% (95% CI: 4.0-18.9%) and the clinical benefit rate at 4 months was 20% (95% CI: 10.6-29.3). The median time to progression was 7.0 weeks (95% CI: 6.4-7.5) and median overall survival was 8.7 months (95% CI: 7.6-9.8) from start of first phase I treatment. No patients discontinued trial because of treatment-related toxicities. Abnormal lactate dehydrogenase, serum albumin <35 mg per 100 ml, >or=5 previous treatment lines, liver metastases and Eastern Cooperative Group performance status >or=2 at study entry were significantly associated with poor overall survival in multivariate analysis.

CONCLUSION

This retrospective analysis provides evidence that patients with MBC tolerate phase I clinical trials and a significant proportion of patients with chemo-refractory disease, particularly those with triple-negative or Her2-positive breast cancer, may benefit from treatment.