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Clinical update: Novel targets in gynecologic malignancies
Clinical Update: Novel Targets in Gynecologic Malignancies Carol Aghajanian The proteasome inhibitor bortezomib has shown activity in chemotherapy-resistant tumors and is approved for treatment of multiple myeloma. The critical component of bortezomib’s antitumor activity is the inhibition of nuclear factor-kappa B (NF-B). Patients with ovarian cancer respond to initial platinum-based chemotherapy, such as cisplatin. However, these agents have been shown to induce tumor cell survival by inducing NF-B activity. Phase I trials of bortezomib in solid tumors, including ovarian cancer, are summarized and examined to determine if the compound can overcome the impact of chemoresistance. In one trial of single-agent bortezomib in advanced malignancies, it was deemed a safe and manageable drug with potential efficacy in solid tumors. A second phase I trial explored inhibition of NF-B with bortezomib to see if the drug rendered platinum agents more sensitive in ovarian cancer patients. Seven of the nine patients in the study had major responses to the combination of carboplatin and bortezomib. The two trials indicate promising results for bortezomib in patients with solid tumors and patients with recurrent ovarian cancer, but further investigation is warranted. Semin Oncol 31(suppl 16):22–26 © 2004 Elsevier Inc. All rights reserved.
O
VARIAN cancer is the leading cause of death for women with gynecologic cancer. It is estimated that in 2004, 25,280 women were diagnosed with ovarian cancer and 16,090 died of the disease.1 The majority of patients with ovarian cancer are diagnosed with advanced disease. Sixty to 80% of patients respond to initial cytoreductive surgery and platinum-based chemotherapy; however, the majority of these patients relapse and eventually die of platinum-resistant disease. New approaches are therefore needed to provide effective therapy with minimal induction of chemotherapy resistance.
The Role of Proteasome Inhibition in Chemoresistant Tumors In preclinical studies, the proteasome inhibitor bortezomib (Velcade for injection; Millennium Pharmaceuticals, Inc,
Memorial Sloan-Kettering Cancer Center, New York, NY. Supported by grant no. 5RO1 CA840009-02 from the National Cancer Institute. Dr Aghajanian has received research grant support from Millennium Pharmaceuticals, Inc; she has received honoraria from Bristol-Myers Squibb Oncology, GlaxoSmithKline, Millennium Pharmaceuticals, Inc, and Ortho Biotech. Address reprint requests to Carol Aghajanian, MD, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, New York, NY 10021.
22
0093-7754/04/$-see front matter © 2004 Elsevier Inc. All rights reserved. doi:10.1053/j.seminoncol.2004.10.015
Cambridge, MA) has shown activity in chemoresistant tumors.2 Bortezomib (formerly PS-341) is approved for the treatment of multiple myeloma, a B-cell malignancy characterized by the proliferation of malignant plasma cells in bone marrow. Bortezomib inhibits the proteasome, which plays an essential role in the degradation of the majority of intracellular proteins, including cell-cycle regulators, signaling molecules, tumor suppressors, transcription factors, and antiapoptotic proteins. Thus, the proteasome is a critical factor in the maintenance of cellular homeostasis. In malignant cells, unregulated gene transcription and translation results in an accumulation of mistranslated or misfolded proteins that are subject to proteasome-mediated degradation. As a result, cancer cells tend to have elevated proteasome activity and are therefore potential targets for proteasome-inhibiting drugs such as bortezomib. Inhibition of nuclear factor-kappa B (NF-B) activity is a critical component of the antitumor activity of bortezomib. NF-B is a transcription factor that upregulates a number of proteins involved in cancer progression, including several proangiogenic factors and antiapoptotic proteins.3 NF-B may be present as a homodimer or heterodimer; the p65/p50 heterodimer is the most common complex.4 In quiescent cells, NF-B is sequestered in the cytoplasm by its inhibitory partner, I-B, which renders NF-B inactive. However, cellular stress signals, such as those induced by chemotherapy, radiation, viruses, growth factors, or antigens, trigger phosphorylation of I-B, which targets
Novel targets in gynecologic malignancies
Figure 1 NF-B activation in ovarian cancer cell lines. Electromobility shift assay reveals increased NF-B expression in nuclear extracts of cisplatin (CDDP)-resistant SK-OV-3 ovarian cancer cells (resist; lanes 3, 4) compared with wild-type cells (wild; lanes 1, 2). This activity is specific to NF-B (lanes 5, 6) and consists of the NF-B p50 (lane 7) and p65 (lane 8) subunits, as shown by supershift analysis (super 1 and super 2, respectively). (Presented during a CME symposium at ASCO 2003. Courtesy of C. Aghajanian.)
it for proteasome-mediated degradation. Release of NF-B by I-B degradation allows it to translocate to the nucleus and effect its transcriptional activation functions. Inhibition of the proteasome via bortezomib prevents degradation of I-B and thus downregulates NF-B–mediated transcriptional activation, thereby inhibiting cancer cell growth and encouraging apoptosis. Multiple myeloma cells often display cell adhesion–mediated drug resistance (CAM-DR), a phenomenon by which the tumor microenvironment protects malignant cells from the effects of cytotoxic drugs (see W.S. Dalton, elsewhere in this issue).5 NF-B is thought to be a critical mediator of the CAM-DR, which results from adhesion between myeloma cells and the bone marrow microenvironment.6 Ongoing research indicates that bortezomib is probably immune to CAM-DR in myeloma cells,5 and results from in vitro studies suggest that bortezomib can overcome resistance to many of the drugs used to treat multiple myeloma, including doxorubicin, dexamethasone, and melphalan.7,8 It is therefore plausible that bortezomib overrides CAM-DR by preventing NF-B activation. These myeloma studies highlight the role of bortezomib in treating chemoresistant malignancies, particularly those involving NF-B activation.
Chemoresistant Solid Tumors Certain types of chemoresistance observed in solid tumors are also associated with NF-B activation.2 Paradoxically, cis-
23 platin and other platinum agents have been shown to induce tumor cell survival by rapidly inducing NF-B activity in SK-OV-3 ovarian cancer cell lines (Fig 1) as well as other platinum-resistant lines (not shown); this is accompanied by degradation of I-B.9 This phenomenon is not limited to platinum agents or to ovarian cancer cell lines.10,11 Cisplatin appears to promote NF-B activity through an increase in I-B kinase (IKK) activity, resulting in the phosphorylation of I-B, which causes it to dissociate from NF-B and become targeted for proteasome-mediated degradation. Constitutive expression of IKK␣ in SK-OV-3 cells increases cisplatin resistance approximately 3-fold (Fig 2). Conversely, transfection with either a mutant IKK␣ or mutant IKK dominantnegative expression vector increases sensitivity to cisplatinmediated cytotoxicity. A similar phenomenon is observed in patients: increased nuclear expression of the p65 subunit of NF-B was observed in a patient with platinum-resistant ovarian cancer (Fig 3). Preclinical experiments indicate that cotreatment with bortezomib abrogates platinum-induced NF-B activation. Bortezomib may therefore be able to overcome resistance to platinum agents by preventing I-B degradation. These results provided the rationale for treating patients with ovarian cancer with a bortezomib/platinum agent combination regimen. However, before initiating combination regimens, bortezomib had to be investigated as a single agent in patients with solid tumors.
Bortezomib in Solid Tumors: A Phase I Trial In a phase I trial of single-agent bortezomib in advanced malignancies, 43 heavily pretreated patients with solid tumors, including four patients with ovarian cancer, were evaluated to determine the maximum tolerated dose (MTD) of bortezomib (range, 0.13 to 1.56 mg/m2) administered as an
Figure 2 IKK expression increases cisplatin resistance in ovarian cancer cell lines. Expression of IKK␣ resulted into an approximately 3-fold increase in resistance to cisplatin (CDDP) in SK-OV-3 ovarian cancer cells. (Presented during a CME symposium at ASCO 2003. Courtesy of C. Aghajanian.)
C. Aghajanian
24
Figure 3 Increased NF-B expression in a patient with platinum-treated ovarian cancer. (A) Pretreatment. (B) Recurrence. Immunostaining with an anti-p65 NF-B antibody shows increased nuclear localization of NF-B after the disease was deemed platinum-resistant (right panel), indicating an increase in NF-B activity in platinum-resistant disease. (Presented during a CME symposium at ASCO 2003. Courtesy of C. Aghajanian.)
intravenous bolus twice weekly for 2 consecutive weeks, followed by a 1-week recovery period.12 The secondary objective was to measure 20S proteasome inhibition in whole blood of treated patients. Inclusion criteria were any type of solid tumor malignancy for which there was no proven effective therapy, Karnofsky performance status ⱖ70%, and adequate bone marrow, liver, renal, and left ventricular function. Exclusion criteria included chemotherapy or radiation therapy within 4 weeks of entry, significant atherosclerotic disease, significant conduction abnormality, orthostatic hypotension, and concurrent therapy with calcium channel blockers, beta blockers, or alpha blockers. Exclusion criteria were based on findings from preclinical studies in which some animals developed unresuscitatable hypotension when a more than 80% inhibition of the proteasome was effected, although this has never been observed in humans.3 Patients had a median age of 53 years (range, 34 to 75 years), and both sexes were represented. Median Karnofsky performance status was 80% (range, 70% to 90%). Tumor types represented included non–small cell lung cancer; colon, head and neck, ovarian, prostate, renal, pancreatic, bladder, cervical, endometrial, esophageal, and gastric cancer; and melanoma. Patients had a median of four prior chemotherapy regimens (range, 1 to 16); 12 patients had prior definitive radiotherapy, and 12 had palliative radiotherapy at some time during the course of their disease. Three to six patients were entered at each dose level; the highest dose level (1.56 mg/m2) was expanded to 12 patients to gather further toxicity information. All patients had to complete one cycle of therapy before escalation to the next dose level. If one patient experienced dose-limiting toxicity (DLT), three additional patients were added to that dose level. If two of six patients experienced DLT, the previous dose level was declared the MTD. No significant toxicity was observed at the first five dose levels. The DLTs were diarrhea and sensory neuropathy. At the 1.56-mg/m2 dose, two patients experienced grade 3 diarrhea,
which was managed with loperamide. Three patients (one at the 1.3-mg/m2 dose; two at the 1.56-mg/m2 dose) developed grade 3 neuropathy. This neuropathy was different than that associated with platinum or taxane neuropathy; it was characterized primarily by pain rather than by loss of sensation. It is important to note that many of these heavily pretreated patients had preexisting neuropathy upon entering this trial. Nonhematologic toxicities were all minor and included fatigue, fever, anorexia, nausea/vomiting, rash, pruritis, and headache. No hematologic DLTs were experienced. While mild thrombocytopenia and neutropenia were experienced with increased dosing, these were not clinically significant and patients rapidly recovered. Pharmacodynamic analysis of patient blood samples collected 1 hour after dosing showed that inhibition of the proteasome 20S core catalytic complex increased with bortezomib dose, with a maximum of approximately 70% inhibition occurring at the highest dose level (Fig 4).12 This suggests that as long as baseline 20S proteasome levels are allowed to return to normal between dosing, there is no apparent change in sensitivity toward bortezomib-induced proteasome inhibition. One major response was observed in a patient with bronchoalveolar non–small cell lung cancer who was refractory to five prior chemotherapy regimens. Upon enrollment, this patient was symptomatic, with heavy sputum production and cough. After two cycles of bortezomib, he experienced a 50% reduction in bilateral pulmonary infiltrative masses (Fig 5) and resolution of his tumor symptoms. In addition, three patients had stable disease: one patient with nasopharyngeal carcinoma had a minor response, and two patients (one with malignant melanoma; one with renal cell carcinoma) had true stable disease. Median duration of stable disease was 4 months (range, 2.5 to 5 months). Based on the results of this study, bortezomib was deemed to be a safe and manageable drug with potential efficacy in the treatment of solid tumors. The MTD was determined to
Novel targets in gynecologic malignancies
25
Figure 4 Relative proteasome activity (compared with baseline) as a function of bortezomib dose. Patient blood samples were collected 1 hour after bortezomib dosing. A clear dose-related inhibition of 20S proteasome activity with increasing dose of bortezomib was observed.12
be 1.5 mg/m2. The recommended bortezomib dose for phase II trials is 1.3 mg/m2 intravenous on days 1, 4, 8, and 11, followed by a 10-day rest period, for a 21-day cycle.12
Bortezomib Plus Carboplatin in Gynecologic Cancer: A Phase I Trial To explore the hypothesis that inhibition of NF-B with bortezomib renders ovarian cancer more sensitive to plat-
inum agents, a phase I trial of bortezomib plus carboplatin in patients with recurrent ovarian cancer has been initiated. The objectives of this trial are to define the MTD and to evaluate the toxicity of this combination, to evaluate the pharmacodynamic effect of carboplatin on bortezomib by measuring whole-blood 20S proteasome inhibition, and to compare the levels of NF-B activation in blood samples following treatment with carboplatin alone in cycle 1 and treatment with bortezomib and carboplatin in cycle 2. Eligibility criteria include Karnofsky performance status ⱖ70%, previous treatment with platinum-based chemo-
Figure 5 Computed tomography scan of a patient with bronchioalveolar non–small cell lung cancer treated with bortezomib. (A) Before treatment, this patient had bilateral pulmonary infiltrative masses. (B) After two cycles of bortezomib, the patient experienced a 50% reduction in his infiltrates and resolution of his tumor symptoms.
C. Aghajanian
26 therapy for management of primary disease and up to two prior regimens (including one nonplatinum therapy) for recurrent disease, grade ⱕ1 neuropathy, and measurable disease according to response evaluation criteria in solid tumors (RECIST). In this study, the carboplatin dose is fixed at an area under the curve (AUC) of 5 on day 1 and bortezomib is given twice weekly for 2 weeks, at escalating doses of 0.75, 1, 1.3, and 1.5 mg/m2, with a 1-week recovery between cycles. Six cycles are planned. Three patients are to be enrolled at each dose level; nine patients have been entered into the first three dose levels thus far.13 CA-125 testing is performed on day 1 of each cycle and response evaluation according to RECIST criteria is performed after every two cycles by computed tomography scan. Because of the potential for neurotoxicity, patients receive a neurologic exam at baseline and after every two cycles; in addition, they fill out Functional Assessment of Cancer Therapy neurotoxicity questionnaires developed by the Gynecology Oncology Group on day 1 of each cycle. The addition of a taxane and evaluation of the three drugs in combination in upfront ovarian cancer, as well as exploration of alternative drug combinations, may be examined in future studies.
Conclusion Resistance to chemotherapies, such as cisplatin, other platinum compounds, and non-platinum agents is common in solid tumors, including ovarian cancer. The development of chemoresistance impacts negatively on therapy outcomes and prognosis. The search for new therapeutic approaches not susceptible to or with minimal induction of resistance has therefore been a major research focus. NF-B activation is associated with certain types of chemoresistance. Inhibition of NF-B activity via proteasome inhibition with bortezomib showed activity in chemotherapy-resistant tumors and in multiple myeloma, a type of cancer often displaying CAM-
DR. Promising results of bortezomib in heavily pretreated patients with solid tumors and in patients with recurrent ovarian cancer, warrant further investigation of proteasome inhibition in larger, randomized trials.
References 1. Jemal A, Tiwari RC, Murray T, et al: Cancer statistics, 2004. CA Cancer J Clin 54:8-29, 2004 2. Cusack JC: Rationale for the treatment of solid tumors with the proteasome inhibitor bortezomib. Cancer Treat Rev 29:21-31, 2003 (suppl 1) 3. Adams J: Preclinical and clinical evaluation of proteasome inhibitor PS-341 for the treatment of cancer. Curr Opin Chem Biol 6:493-500, 2002 4. Berenson JR, Ma HM, Vescio R: The role of nuclear factor-kappaB in the biology and treatment of multiple myeloma. Semin Oncol 28:626-633, 2001 5. Hazlehurst LA, Dalton WS: Mechanisms associated with cell adhesion mediated drug resistance (CAM-DR) in hematopoietic malignancies. Cancer Metastasis Rev 20:43-50, 2001 6. Landowski TH, Olashaw NE, Agrawal D, et al: Cell adhesion-mediated drug resistance (CAM-DR) is associated with activation of NF-kappa B (RelB/p50) in myeloma cells. Oncogene 22:2417-2421, 2003 7. Hideshima T, Richardson P, Chauhan D, et al: The proteasome inhibitor PS-341 inhibits growth, induces apoptosis, and overcomes drug resistance in human multiple myeloma cells. Cancer Res 61:30713076, 2001 8. Ma MH, Yang HH, Parker K, et al: The proteasome inhibitor PS-341 markedly enhances sensitivity of multiple myeloma tumor cells to chemotherapeutic agents. Clin Cancer Res 9:1136-1144, 2003 9. Yan XJ, Rosales N, Aghajanian C, et al: Cisplatin induces NF-B activity through IB kinase dependent pathway. Proc Am Assoc Cancer Res 40:195, 1999 (abstr 1299) 10. Wang W, Abbruzzese JL, Evans DB, et al: The nuclear factor-kappa B RelA transcription factor is constitutively activated in human pancreatic adenocarcinoma cells. Clin Cancer Res 5:119-127, 1999 11. Cusack JC Jr, Liu R, Houston M, et al: Enhanced chemosensitivity to CPT-11 with proteasome inhibitor PS-341: Implication for systemic nuclear factor-kappaB inhibitor. Cancer Res 61:3535-3540, 2001 12. Aghajanian C, Soignet S, Dizon DS, et al: A phase I trial of the novel proteasome inhibitor PS341 in advanced solid tumor malignancies. Clin Cancer Res 8:2505-2511, 2002 13. Aghajanian C, Dizon D, Yan XJ, et al: Phase I trial of PS-341 and carboplatin in recurrent ovarian cancer. Proc Am Soc Clin Oncol 22: 452, 2003 (abstr 1815)
O
VARIAN cancer is the leading cause of death for women with gynecologic cancer. It is estimated that in 2004, 25,280 women were diagnosed with ovarian cancer and 16,090 died of the disease.1 The majority of patients with ovarian cancer are diagnosed with advanced disease. Sixty to 80% of patients respond to initial cytoreductive surgery and platinum-based chemotherapy; however, the majority of these patients relapse and eventually die of platinum-resistant disease. New approaches are therefore needed to provide effective therapy with minimal induction of chemotherapy resistance.
The Role of Proteasome Inhibition in Chemoresistant Tumors In preclinical studies, the proteasome inhibitor bortezomib (Velcade for injection; Millennium Pharmaceuticals, Inc,
Memorial Sloan-Kettering Cancer Center, New York, NY. Supported by grant no. 5RO1 CA840009-02 from the National Cancer Institute. Dr Aghajanian has received research grant support from Millennium Pharmaceuticals, Inc; she has received honoraria from Bristol-Myers Squibb Oncology, GlaxoSmithKline, Millennium Pharmaceuticals, Inc, and Ortho Biotech. Address reprint requests to Carol Aghajanian, MD, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, New York, NY 10021.
22
0093-7754/04/$-see front matter © 2004 Elsevier Inc. All rights reserved. doi:10.1053/j.seminoncol.2004.10.015
Cambridge, MA) has shown activity in chemoresistant tumors.2 Bortezomib (formerly PS-341) is approved for the treatment of multiple myeloma, a B-cell malignancy characterized by the proliferation of malignant plasma cells in bone marrow. Bortezomib inhibits the proteasome, which plays an essential role in the degradation of the majority of intracellular proteins, including cell-cycle regulators, signaling molecules, tumor suppressors, transcription factors, and antiapoptotic proteins. Thus, the proteasome is a critical factor in the maintenance of cellular homeostasis. In malignant cells, unregulated gene transcription and translation results in an accumulation of mistranslated or misfolded proteins that are subject to proteasome-mediated degradation. As a result, cancer cells tend to have elevated proteasome activity and are therefore potential targets for proteasome-inhibiting drugs such as bortezomib. Inhibition of nuclear factor-kappa B (NF-B) activity is a critical component of the antitumor activity of bortezomib. NF-B is a transcription factor that upregulates a number of proteins involved in cancer progression, including several proangiogenic factors and antiapoptotic proteins.3 NF-B may be present as a homodimer or heterodimer; the p65/p50 heterodimer is the most common complex.4 In quiescent cells, NF-B is sequestered in the cytoplasm by its inhibitory partner, I-B, which renders NF-B inactive. However, cellular stress signals, such as those induced by chemotherapy, radiation, viruses, growth factors, or antigens, trigger phosphorylation of I-B, which targets
Novel targets in gynecologic malignancies
Figure 1 NF-B activation in ovarian cancer cell lines. Electromobility shift assay reveals increased NF-B expression in nuclear extracts of cisplatin (CDDP)-resistant SK-OV-3 ovarian cancer cells (resist; lanes 3, 4) compared with wild-type cells (wild; lanes 1, 2). This activity is specific to NF-B (lanes 5, 6) and consists of the NF-B p50 (lane 7) and p65 (lane 8) subunits, as shown by supershift analysis (super 1 and super 2, respectively). (Presented during a CME symposium at ASCO 2003. Courtesy of C. Aghajanian.)
it for proteasome-mediated degradation. Release of NF-B by I-B degradation allows it to translocate to the nucleus and effect its transcriptional activation functions. Inhibition of the proteasome via bortezomib prevents degradation of I-B and thus downregulates NF-B–mediated transcriptional activation, thereby inhibiting cancer cell growth and encouraging apoptosis. Multiple myeloma cells often display cell adhesion–mediated drug resistance (CAM-DR), a phenomenon by which the tumor microenvironment protects malignant cells from the effects of cytotoxic drugs (see W.S. Dalton, elsewhere in this issue).5 NF-B is thought to be a critical mediator of the CAM-DR, which results from adhesion between myeloma cells and the bone marrow microenvironment.6 Ongoing research indicates that bortezomib is probably immune to CAM-DR in myeloma cells,5 and results from in vitro studies suggest that bortezomib can overcome resistance to many of the drugs used to treat multiple myeloma, including doxorubicin, dexamethasone, and melphalan.7,8 It is therefore plausible that bortezomib overrides CAM-DR by preventing NF-B activation. These myeloma studies highlight the role of bortezomib in treating chemoresistant malignancies, particularly those involving NF-B activation.
Chemoresistant Solid Tumors Certain types of chemoresistance observed in solid tumors are also associated with NF-B activation.2 Paradoxically, cis-
23 platin and other platinum agents have been shown to induce tumor cell survival by rapidly inducing NF-B activity in SK-OV-3 ovarian cancer cell lines (Fig 1) as well as other platinum-resistant lines (not shown); this is accompanied by degradation of I-B.9 This phenomenon is not limited to platinum agents or to ovarian cancer cell lines.10,11 Cisplatin appears to promote NF-B activity through an increase in I-B kinase (IKK) activity, resulting in the phosphorylation of I-B, which causes it to dissociate from NF-B and become targeted for proteasome-mediated degradation. Constitutive expression of IKK␣ in SK-OV-3 cells increases cisplatin resistance approximately 3-fold (Fig 2). Conversely, transfection with either a mutant IKK␣ or mutant IKK dominantnegative expression vector increases sensitivity to cisplatinmediated cytotoxicity. A similar phenomenon is observed in patients: increased nuclear expression of the p65 subunit of NF-B was observed in a patient with platinum-resistant ovarian cancer (Fig 3). Preclinical experiments indicate that cotreatment with bortezomib abrogates platinum-induced NF-B activation. Bortezomib may therefore be able to overcome resistance to platinum agents by preventing I-B degradation. These results provided the rationale for treating patients with ovarian cancer with a bortezomib/platinum agent combination regimen. However, before initiating combination regimens, bortezomib had to be investigated as a single agent in patients with solid tumors.
Bortezomib in Solid Tumors: A Phase I Trial In a phase I trial of single-agent bortezomib in advanced malignancies, 43 heavily pretreated patients with solid tumors, including four patients with ovarian cancer, were evaluated to determine the maximum tolerated dose (MTD) of bortezomib (range, 0.13 to 1.56 mg/m2) administered as an
Figure 2 IKK expression increases cisplatin resistance in ovarian cancer cell lines. Expression of IKK␣ resulted into an approximately 3-fold increase in resistance to cisplatin (CDDP) in SK-OV-3 ovarian cancer cells. (Presented during a CME symposium at ASCO 2003. Courtesy of C. Aghajanian.)
C. Aghajanian
24
Figure 3 Increased NF-B expression in a patient with platinum-treated ovarian cancer. (A) Pretreatment. (B) Recurrence. Immunostaining with an anti-p65 NF-B antibody shows increased nuclear localization of NF-B after the disease was deemed platinum-resistant (right panel), indicating an increase in NF-B activity in platinum-resistant disease. (Presented during a CME symposium at ASCO 2003. Courtesy of C. Aghajanian.)
intravenous bolus twice weekly for 2 consecutive weeks, followed by a 1-week recovery period.12 The secondary objective was to measure 20S proteasome inhibition in whole blood of treated patients. Inclusion criteria were any type of solid tumor malignancy for which there was no proven effective therapy, Karnofsky performance status ⱖ70%, and adequate bone marrow, liver, renal, and left ventricular function. Exclusion criteria included chemotherapy or radiation therapy within 4 weeks of entry, significant atherosclerotic disease, significant conduction abnormality, orthostatic hypotension, and concurrent therapy with calcium channel blockers, beta blockers, or alpha blockers. Exclusion criteria were based on findings from preclinical studies in which some animals developed unresuscitatable hypotension when a more than 80% inhibition of the proteasome was effected, although this has never been observed in humans.3 Patients had a median age of 53 years (range, 34 to 75 years), and both sexes were represented. Median Karnofsky performance status was 80% (range, 70% to 90%). Tumor types represented included non–small cell lung cancer; colon, head and neck, ovarian, prostate, renal, pancreatic, bladder, cervical, endometrial, esophageal, and gastric cancer; and melanoma. Patients had a median of four prior chemotherapy regimens (range, 1 to 16); 12 patients had prior definitive radiotherapy, and 12 had palliative radiotherapy at some time during the course of their disease. Three to six patients were entered at each dose level; the highest dose level (1.56 mg/m2) was expanded to 12 patients to gather further toxicity information. All patients had to complete one cycle of therapy before escalation to the next dose level. If one patient experienced dose-limiting toxicity (DLT), three additional patients were added to that dose level. If two of six patients experienced DLT, the previous dose level was declared the MTD. No significant toxicity was observed at the first five dose levels. The DLTs were diarrhea and sensory neuropathy. At the 1.56-mg/m2 dose, two patients experienced grade 3 diarrhea,
which was managed with loperamide. Three patients (one at the 1.3-mg/m2 dose; two at the 1.56-mg/m2 dose) developed grade 3 neuropathy. This neuropathy was different than that associated with platinum or taxane neuropathy; it was characterized primarily by pain rather than by loss of sensation. It is important to note that many of these heavily pretreated patients had preexisting neuropathy upon entering this trial. Nonhematologic toxicities were all minor and included fatigue, fever, anorexia, nausea/vomiting, rash, pruritis, and headache. No hematologic DLTs were experienced. While mild thrombocytopenia and neutropenia were experienced with increased dosing, these were not clinically significant and patients rapidly recovered. Pharmacodynamic analysis of patient blood samples collected 1 hour after dosing showed that inhibition of the proteasome 20S core catalytic complex increased with bortezomib dose, with a maximum of approximately 70% inhibition occurring at the highest dose level (Fig 4).12 This suggests that as long as baseline 20S proteasome levels are allowed to return to normal between dosing, there is no apparent change in sensitivity toward bortezomib-induced proteasome inhibition. One major response was observed in a patient with bronchoalveolar non–small cell lung cancer who was refractory to five prior chemotherapy regimens. Upon enrollment, this patient was symptomatic, with heavy sputum production and cough. After two cycles of bortezomib, he experienced a 50% reduction in bilateral pulmonary infiltrative masses (Fig 5) and resolution of his tumor symptoms. In addition, three patients had stable disease: one patient with nasopharyngeal carcinoma had a minor response, and two patients (one with malignant melanoma; one with renal cell carcinoma) had true stable disease. Median duration of stable disease was 4 months (range, 2.5 to 5 months). Based on the results of this study, bortezomib was deemed to be a safe and manageable drug with potential efficacy in the treatment of solid tumors. The MTD was determined to
Novel targets in gynecologic malignancies
25
Figure 4 Relative proteasome activity (compared with baseline) as a function of bortezomib dose. Patient blood samples were collected 1 hour after bortezomib dosing. A clear dose-related inhibition of 20S proteasome activity with increasing dose of bortezomib was observed.12
be 1.5 mg/m2. The recommended bortezomib dose for phase II trials is 1.3 mg/m2 intravenous on days 1, 4, 8, and 11, followed by a 10-day rest period, for a 21-day cycle.12
Bortezomib Plus Carboplatin in Gynecologic Cancer: A Phase I Trial To explore the hypothesis that inhibition of NF-B with bortezomib renders ovarian cancer more sensitive to plat-
inum agents, a phase I trial of bortezomib plus carboplatin in patients with recurrent ovarian cancer has been initiated. The objectives of this trial are to define the MTD and to evaluate the toxicity of this combination, to evaluate the pharmacodynamic effect of carboplatin on bortezomib by measuring whole-blood 20S proteasome inhibition, and to compare the levels of NF-B activation in blood samples following treatment with carboplatin alone in cycle 1 and treatment with bortezomib and carboplatin in cycle 2. Eligibility criteria include Karnofsky performance status ⱖ70%, previous treatment with platinum-based chemo-
Figure 5 Computed tomography scan of a patient with bronchioalveolar non–small cell lung cancer treated with bortezomib. (A) Before treatment, this patient had bilateral pulmonary infiltrative masses. (B) After two cycles of bortezomib, the patient experienced a 50% reduction in his infiltrates and resolution of his tumor symptoms.
C. Aghajanian
26 therapy for management of primary disease and up to two prior regimens (including one nonplatinum therapy) for recurrent disease, grade ⱕ1 neuropathy, and measurable disease according to response evaluation criteria in solid tumors (RECIST). In this study, the carboplatin dose is fixed at an area under the curve (AUC) of 5 on day 1 and bortezomib is given twice weekly for 2 weeks, at escalating doses of 0.75, 1, 1.3, and 1.5 mg/m2, with a 1-week recovery between cycles. Six cycles are planned. Three patients are to be enrolled at each dose level; nine patients have been entered into the first three dose levels thus far.13 CA-125 testing is performed on day 1 of each cycle and response evaluation according to RECIST criteria is performed after every two cycles by computed tomography scan. Because of the potential for neurotoxicity, patients receive a neurologic exam at baseline and after every two cycles; in addition, they fill out Functional Assessment of Cancer Therapy neurotoxicity questionnaires developed by the Gynecology Oncology Group on day 1 of each cycle. The addition of a taxane and evaluation of the three drugs in combination in upfront ovarian cancer, as well as exploration of alternative drug combinations, may be examined in future studies.
Conclusion Resistance to chemotherapies, such as cisplatin, other platinum compounds, and non-platinum agents is common in solid tumors, including ovarian cancer. The development of chemoresistance impacts negatively on therapy outcomes and prognosis. The search for new therapeutic approaches not susceptible to or with minimal induction of resistance has therefore been a major research focus. NF-B activation is associated with certain types of chemoresistance. Inhibition of NF-B activity via proteasome inhibition with bortezomib showed activity in chemotherapy-resistant tumors and in multiple myeloma, a type of cancer often displaying CAM-
DR. Promising results of bortezomib in heavily pretreated patients with solid tumors and in patients with recurrent ovarian cancer, warrant further investigation of proteasome inhibition in larger, randomized trials.
References 1. Jemal A, Tiwari RC, Murray T, et al: Cancer statistics, 2004. CA Cancer J Clin 54:8-29, 2004 2. Cusack JC: Rationale for the treatment of solid tumors with the proteasome inhibitor bortezomib. Cancer Treat Rev 29:21-31, 2003 (suppl 1) 3. Adams J: Preclinical and clinical evaluation of proteasome inhibitor PS-341 for the treatment of cancer. Curr Opin Chem Biol 6:493-500, 2002 4. Berenson JR, Ma HM, Vescio R: The role of nuclear factor-kappaB in the biology and treatment of multiple myeloma. Semin Oncol 28:626-633, 2001 5. Hazlehurst LA, Dalton WS: Mechanisms associated with cell adhesion mediated drug resistance (CAM-DR) in hematopoietic malignancies. Cancer Metastasis Rev 20:43-50, 2001 6. Landowski TH, Olashaw NE, Agrawal D, et al: Cell adhesion-mediated drug resistance (CAM-DR) is associated with activation of NF-kappa B (RelB/p50) in myeloma cells. Oncogene 22:2417-2421, 2003 7. Hideshima T, Richardson P, Chauhan D, et al: The proteasome inhibitor PS-341 inhibits growth, induces apoptosis, and overcomes drug resistance in human multiple myeloma cells. Cancer Res 61:30713076, 2001 8. Ma MH, Yang HH, Parker K, et al: The proteasome inhibitor PS-341 markedly enhances sensitivity of multiple myeloma tumor cells to chemotherapeutic agents. Clin Cancer Res 9:1136-1144, 2003 9. Yan XJ, Rosales N, Aghajanian C, et al: Cisplatin induces NF-B activity through IB kinase dependent pathway. Proc Am Assoc Cancer Res 40:195, 1999 (abstr 1299) 10. Wang W, Abbruzzese JL, Evans DB, et al: The nuclear factor-kappa B RelA transcription factor is constitutively activated in human pancreatic adenocarcinoma cells. Clin Cancer Res 5:119-127, 1999 11. Cusack JC Jr, Liu R, Houston M, et al: Enhanced chemosensitivity to CPT-11 with proteasome inhibitor PS-341: Implication for systemic nuclear factor-kappaB inhibitor. Cancer Res 61:3535-3540, 2001 12. Aghajanian C, Soignet S, Dizon DS, et al: A phase I trial of the novel proteasome inhibitor PS341 in advanced solid tumor malignancies. Clin Cancer Res 8:2505-2511, 2002 13. Aghajanian C, Dizon D, Yan XJ, et al: Phase I trial of PS-341 and carboplatin in recurrent ovarian cancer. Proc Am Soc Clin Oncol 22: 452, 2003 (abstr 1815)