A phase II study of trastuzumab-DM1 (T-DM1), a HER2 antibody-drug conjugate (ADC), in patients (pts) with HER2+ metastatic breast cancer (MBC): Final results

1017

Background: T-DM1 is an ADC that combines the biological activity of trastuzumab (T) with targeted delivery of a potent antimicrotubule agent, DM1, to HER2-expressing cancer cells. In a phase I study, T-DM1 was administered IV q3w to pts with HER2+ MBC who had progressed on T + chemotherapy. T-DM1 was well-tolerated at the maximum tolerated dose (MTD) of 3.6 mg/kg, with no reports of cardiac toxicity. The confirmed objective response rate (ORR) for the 9 pts with measurable disease treated at the MTD was 44%. The phase II study described here further assesses tolerability and activity of T-DM1. Methods: This was a multi-institutional, open-label, single-arm phase II study, to enroll 100 pts. All eligible pts had progressed on HER2-directed therapy and had received chemotherapy in the metastatic setting. T-DM1 was administered at 3.6 mg/kg IV q3w. Primary objectives were assessment of ORR and of safety and tolerability. Results: As of the August 29, 2008, data-cut, 112 patients had enrolled, with baseline median age 54.5 (range 33–82); ECOG PS 2 or 3, 80%; 68.7% with > 3 sites of metastatic disease; median 3 (range 1–14) prior chemotherapy agents for metastatic disease, median 76.3 weeks prior T, and 55.4% with previous lapatinib. Due to limited F/U, the median number of T-DM1 cycles received was 5 (range 1–16), and 19 of the 107 efficacy evaluable patients had only one post-baseline tumor assessment. Fifty-six pts had discontinued study treatment. With a median follow-up of 4.4 mos, there were 42 (39.3%) ORs (CR or PR), 29 (27.1%) of which have been confirmed by follow-up (F/U) imaging. Among the subgroup of pts who had either >6 months F/U or had discontinued from the study at any time (n = 76) there were 33 ORs (43.4%), 29 (38.2%) of which were confirmed by F/U imaging. The most common grade 3–4 AE was thrombocytopenia (7.1%). Updated data will be presented at the meeting, including updated ORR, 6-month clinical benefit rate, ORR by independent review, progression-free survival, and duration of response. Conclusions: T-DM1 has single-agent activity in pts with previously treated, HER2+ MBC, and is well tolerated at the recommended phase II dose.

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Quantitative assessment of HER2 status and correlation with efficacy for patients (pts) with metastatic breast cancer (MBC) in a phase II study of trastuzumab-DM1 (T-DM1)

1003

Background: The antibody-drug conjugate T-DM1 combines the biological activity of trastuzumab with targeted delivery of an anti-microtubule agent (DM1) to HER-2-expressing cancer cells. This analysis examines correlation of response to T-DM1 with HER-2 status, as assessed by fluorescent in situ hybridization (FISH), immunohistochemistry (IHC), mRNA quantitative real-time polymerase chain reaction (qRT-PCR), and enzyme-linked immunosorbent assay (ELISA) (HER-2 extracellular domain [ECD]), for pts enrolled in TDM4258g, a phase II study of T-DM1 in pts with MBC. Methods: TDM4258g is an open-label, single-arm study of T-DM1 administered at 3.6 mg/kg IV q3w. Pts had progressed on HER-2-directed therapy and received chemotherapy in the metastatic setting and were HER-2 + based on local testing. Archival tissue (paraffin block or >7 unstained tumor slides) was collected for retrospective central laboratory testing. HER-2 DNA amplification was determined by FISH, and protein levels by IHC. qRT-PCR for HER-2 was performed on extracted RNA; baseline HER-2 ECD ELISA was performed on pt sera. HER-2 data for each pt were compared with pt's best response. Results: As of August 29, 2008, 112 pts had enrolled; 107 were efficacy-evaluable pts with median 4.4 mos follow-up. There were 42/107 (39.3%) partial responses (PR) (investigator assessment). Of 86 pts centrally tested, 64 (74.4%) were confirmed HER-2+ (FISH+ and/or IHC 3+), with 32/64 (50%) PR. Of 76 pts tested by both FISH and IHC, 15/76 (19.7%) were confirmed HER-2- (FISH- and IHC 2+/1/0), with 2/15 (13.3%) PR. In HER-2+ pts, response rates did not correlate with high versus low FISH+ counts, nor with HER-2 ECD levels. Among 39 HER-2+ (FISH+ and/or IHC3+) efficacy-evaluable pts with qRT-PCR data, there were 13/19 (68.4%) PR for pts with qRT-PCR above median levels, and 7/20 (35.0%) PR for pts with qRT-PCR below median. Conclusions: HER-2+ pts (by central retesting) had better responses to T-DM1 than HER-2- pts, although a small number of PR were observed in HER-2- pts. Assessment of HER-2 expression by qRT-PCR may identify pts more likely to respond to T-DM1 therapy. Updated data, including additional diagnostic markers, will be presented at the meeting.

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Clinical pharmacokinetics of erlotinib (E) in glioblastoma multiforme (GBM) patients and its implication for dosing

2010

Background: E is an orally active, highly potent and selective inhibitor of the epidermal growth factor receptor (EGFR). Preliminary results from both Phase I and Phase II trials of E in GBM patients have been reported (ASCO 2003, Abs#394 and ASCO 2004, Abs#1555). The purpose of this analysis is to characterize E PK in this patient population when administered with or without CYP3A4 enzyme inducing anti-epileptic drugs (EIAEDs) and to identify a dose to provide equivalent exposure during concomitant therapy in GBM patients. Methods: Intensive PK data were collected in the Phase I study and plasma trough concentration data were collected in the Phase II study at steady-state. A total of 775 E concentrations from 107 patients were available for the analysis. A population PK approach (NONMEM) was used to characterize the clinical PK in this patient population and the effect of EIAEDs on the PK of E. Results: Co-administration of EIAEDs was shown to increase the E clearance (CL/F) by 230% in GBM patients. This effect is similar to that seen in a previous drug-drug interaction study with a CYP3A4 enzyme inducer (rifampicin) in healthy volunteers. For patients with no EIAEDs, population estimates and the %CV of inter-individual variance for CL/F and Vc/F of erlotinib were 5.63 L/hr (44%) and 388 L (40%), respectively. Conclusions: Based on the modeling results, for GBM patients with EIAEDs, an estimate of erlotinib dose of 500 mg/d is needed to achieve an equivalent exposure as patients who receive the dose of 150 mg/d with no EIAEDs. The new population PK model provides an operational tool to predict E exposure during treatment, and simulate alternative dosing regimens for GBM patients.

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Oral eniluracil/5-fluorouracil in patients with inoperable hepatocellular carcinoma

BACKGROUND

Conventional systemic chemotherapy currently available for patients with inoperable hepatocellular carcinoma is ineffective. The purpose of this study was to evaluate the safety and efficacy of eniluracil/5-fluorouracil (5-FU) in the treatment of patients with this highly refractory disease.

PATIENTS AND METHODS

This multicenter, open-label study evaluated a 28-day oral regimen of 5-FU (1 mg/m2 twice daily) plus the dihydropyrimidine dehydrogenase inhibitor, eniluracil (10 mg/m2 twice daily), in patients with chemotherapy-naive or anthracycline-refractory inoperable hepatocellular carcinoma.

RESULTS

A total of 36 patients enrolled into the study. No patient showed a confirmed partial or complete tumor response, although nine patients (25%) had a best response of stable disease. The median duration of progression-free survival was 9.6 weeks [95% confidence interval (CI) 9.1-10.6 weeks], and the median duration of overall survival was 32.7 weeks (95% CI 17.4-71.6 weeks). Eniluracil/5-FU was well tolerated. Diarrhea, the most frequent treatment-related non-hematological toxicity, occurred in 11 patients (31%). Hematological toxicities were infrequent and usually mild.

CONCLUSIONS

Eniluracil/5-FU as a 28-day oral outpatient regimen is well tolerated by patients with inoperable hepatocellular carcinoma, although minimal activity was observed when given as monotherapy at the dose used in this study.

The restricted cellular host range of human herpesvirus 8

DESIGN

A selection of primary and transformed cell types were evaluated for their susceptibility to infection with human herpesvirus 8 (HHV-8)/Kaposi's sarcoma-associated herpesvirus.

METHODS

Sources of HHV-8 included Kaposi's sarcoma lesion punch biopsies that were either cocultured directly with target cells or that were first cocultured with human lymphocytes to derive HHV-8-containing fluids that were inoculated onto target cells. HHV-8 was also obtained from primary effusion lymphoma-derived cell lines. Techniques to detect infection included the PCR, immunofluorescence assays and in situ hybridization.

RESULTS

Susceptible cells included human umbilical cord blood mononuclear cells (UCMC), adult CD19 B cells, macrophages and certain endothelial cells of human and animal origin, including some that are transformed with human papilloma virus type 16 E6 and E7 genes. The infection of lymphocytes did not yield established lymphoblastoid cell lines (LCL) and virus infection persisted for only 4-7 days. However, long-term HHV-8 infection of UCMC could be achieved by coinfection with Epstein-Barr virus. HHV-8 could also infect UCMC LCL recently derived by Epstein-Barr virus transformation, but long-established LCL could not be infected with HHV-8.

CONCLUSIONS

These data provide further biological evidence in cell culture for the limited cellular host range of HHV-8 to CD19 B cells, macrophages, and certain endothelial cells.

The significance of pretreatment CD4 count on the outcome and treatment tolerance of HIV-positive patients with anal cancer

PURPOSE

To assess the outcome and tolerance of HIV-positive patients with anal cancer to standard therapy based on their pretreatment CD4 count.

METHODS AND MATERIALS

Between 1991 and 1997, 17 HIV-positive patients with anal cancer and documented pretreatment CD4 counts were treated at the University of California, San Francisco or its affiliated hospitals with either concurrent chemotherapy and radiation or radiation alone. The outcome and complications of treatment were correlated with the patients' pretreatment CD4 count.

RESULTS

Disease for all 9 patients with pretreatment CD4 counts > or = 200 was controlled with chemoradiation. Although four required a treatment break of 2 weeks because of toxicity, none required hospitalization. Of the 8 patients with pretreatment CD4 counts < 200, 4 experienced decreased counts, intractable diarrhea, or moist desquamation requiring hospitalization. Additionally, 4 of these 8 ultimately required a colostomy either for a therapy-related complication or for salvage. Nevertheless, 6/7 in this group who received concurrent chemotherapy and radiation had their disease controlled, whereas the patient treated with radiation alone failed and required a colostomy for salvage.

CONCLUSION

Patients with CD4 > or = 200 had excellent disease control with acceptable morbidity. Patients with CD4 < 200 had markedly increased morbidity; however, disease was ultimately controlled in 7/8 patients.

Advances and future challenges in non-Hodgkin's lymphoma

The mortality and morbidity burden of Non-Hodgkin's lymphoma (NHL) is increasing within the human immunodeficiency virus- (HIV-) infected population. Recent improvements in HIV management has meant overall reductions in deaths, especially those due to opportunistic infections, and while the outcome of HIV-related NHL may now be somewhat less grim, the incidence remains high and outcome poor. The median survival of those with HIV-related NHL is only approximately 7 months, although those with high CD4 lymphocyte counts seem to do somewhat better. Improved management of the underlying HIV infection, more effective infusional chemotherapy regimens, moderately effective second line regimens, and new investigational approaches all offer promising hope that improvements will soon be seen for the treatment of HIV-related systemic NHL. Immunotherapy, monoclonal antibodies, and adoptive immunotherapy targeting Epstein Barr virus (EBV) all represent novel experimental treatment approaches that are becoming possible based on our increased understanding of the pathogenesis of HIV-related lymphoma. Primary central nervous system lymphoma (PCNSL) in HIV patients has declined in incidence and there now is a rapid, less invasive diagnostic test. The presence of EBV DNA in the cerebral spinal fluid of HIV patients with focal brain lesions strongly suggests a diagnosis of PCNSL. Unfortunately, this disease remains difficult to treat in such an immunocompromised patient population. Further work is needed in order to prevent and effectively manage these diseases.

Intra-abdominal desmoplastic small round-cell tumor: expansion of the pathologic profile

This report describes an intra-abdominal desmoplastic small round-cell tumor in a 29-year-old man that significantly differed from the classically described appearances of this unique tumor. It showed extensive papillary areas, no necrosis, and very little desmoplasia. The latter was limited, paucicellular, and present in areas separate from the papillary structures. Also, areas of back-to-back, single-cell infiltration, which mimicked lobular breast carcinoma, were present. These epithelial features suggested the diagnosis of adenocarcinoma or peculiar mesothelioma. But, the immunohistochemical features (tumor cells positive for keratin, desmin, and vimentin) were more consistent with an intra-abdominal desmoplastic small round-cell tumor. The diagnosis became clear after application of reverse transcriptase-polymerase chain reaction techniques to formalin-fixed, paraffin-embedded tissue, which showed the presence of a 100-base pair product containing the fusion junction of Ewing's sarcoma-1 exon 7 to Wilms' tumor-1 exon 8. This feature is considered unique to intra-abdominal desmoplastic small round-cell tumors. This case illustrates the less common histologic findings that can be found in intra-abdominal desmoplastic small round-cell tumor. This deviation from the classic histologic findings may be an expression of an uncommon morphologic variant and/or partially produced by the effects of prior chemotherapy. In either event, only by illustrating the various histologic appearances of intra-abdominal desmoplastic small round-cell tumor are the chances increased for the accurate diagnosis of this aggressive neoplasm with a poor prognosis.