Sequence specificity of docetaxel (Doc) and the proteasome inhibitor PS-341 combinations in androgen-independent (AI) prostate cancer (CaP)

13150

Background: AI CaP is an invariably fatal disease. While treatment with Doc, a microtubule-stabilizing taxane, improves survival, patient outcomes remain suboptimal. PS-341 inhibits degradation of cell cycle and tumor suppressor proteins resulting in cycle arrest and apoptosis. We hypothesized that the combination of Doc with PS-341 would abrogate the abnormal survival response seen in AI CaP and lead to improved tumor cell kill, but that results would be dependent on administration schedule due to interactive cell cycle kinetics. Methods: The PC3 cell line model of AI CaP was evaluated in vitro and in vivo to determine response to Doc or PS-341 alone, and in combination in sequences of PS-341→Doc, Doc→PS-341, and simultaneous (PS-341 + Doc). Cell cycle and protein analyses were performed by flow cytometry and Western blotting, respectively. For nu/nu mouse xenografts, 5 × 106 cells were injected subcutaneously into each flank. The agents were administered either together or 24hr apart, with all regimens given weekly [IP doses: Doc: 10 mg/kg; PS-341: 0.5 mg/kg]. Results: in vitro: Each combination showed an increased apoptotic sub-G1 population versus untreated cells, in addition to altered cell cycling in a sequence-specific manner. Of the combinations, PS-341 + Doc showed the largest sub-G1 while Doc→PS-341 had the lowest sub-G1 but the largest S-phase content; in vivo: PS-341 + Doc showed a cytotoxic effect (reduction in tumor volume) while the combinations of Doc→PS-341 and PS-341→Doc both showed growth inhibition (stabilization of tumor growth) as best response. Conclusions: Combinations of PS-341 and Doc have sequence specific cell cycle effects leading to increases in apoptosis (PS-341 + Doc) or cell cycle arrest (Doc→PS-341). Clinical validation of these findings is warranted. (ACS: CRTG-0019701-CCE)

No significant financial relationships to disclose.

Elevated osteopontin (OPN) plasma levels are highly prognostic in advanced non-small cell lung cancer (NSCLC): Analysis of SWOG S0003

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Background: OPN is a secreted glycoprotein with a diverse array of functions, including induction of uPA & increased cell migration. OPN has been shown to be elevated in a number of tumor types, & its downregulation reduces tumorigenicity & metastasis in tumor models. High levels have also been associated with tumor hypoxia/angiogenesis, as are vascular endothelial growth factor (VEGF) & plasminogen activator inhibitor (PAI-1). We hypothesized that secreted levels of these biomarkers would correlate with clinical outcome after treatment. Methods: Plasma concentrations of OPN, VEGF & PAI-1 were measured by ELISA in 160 NSCLC patients enrolled on the Southwest Oncology Group (SWOG) trial S0003 (paclitaxel/carboplatin ± the hypoxic cytotoxin tirapazamine). Post-treatment plasma samples were available in 56 patients. Results: Baseline OPN plasma levels correlated significantly with patient overall survival (OS). High interpatient variability was observed, with levels ranging from undetectable to 2560 ng/ml, (median: 606.5 ng/ml). When dichotomized, median OS was 11 months for patients below median OPN levels & 7 months for those above (p = 0.004). Survival decreases with increasing OPN concentration. Furthermore, OPN levels correlated with response rate (RR) (median responders: 497; median non-responders: 698 ng/ml. Wilcoxon rank-sum p = 0.03). No association between baseline levels of either VEGF or PAI-1 with RR or OS was observed. However, plasma levels of both PAI-1 & VEGF were significantly inter-related & trended together (p < 0.0001), & both decreased significantly after treatment (p = 0.0004 & 0.04, respectively). Median decrease: OPN: 17%, PAI: 44%, VEGF: 42%. No significant differences were observed between study arms, suggesting that OPN is prognostic in NSCLC, but not predictive for response to tirapazamine. Conclusions: 1) There is a great need for development of tumor biomarkers which can be serially assessed pre- & post-therapy. 2) High OPN plasma levels were significantly associated with reduced RR & OS for patients on this trial. OPN is a strong candidate for inclusion in a panel of prognostic (& perhaps predictive) markers for NSCLC. Supported by the Hope Foundation & R01-CA107228.

No significant financial relationships to disclose.

Second Japan-SWOG common arm analysis of paclitaxel/carboplatin in advanced stage non-small cell lung cancer (NSCLC): A model for testing population-related pharmacogenomics

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Background: Whether results of clinical trials performed outside the United States (US) can be fully extrapolated to US populations remains in question due to potential differences in trial designs, study-specific criteria, patient demographics, and population-related pharmacogenomics. The first of these comparisons, FACS-S0003 has been presented (Gandara, PASCO, 2004). Here we present the second comparative analysis. Methods: We prospectively designed & conducted 3 separate phase III trials in advanced NSCLC linked by a “common arm” with identical eligibility, staging, response & toxicity criteria, to: 1) determine similarities & differences in patient demographics & outcomes in cooperative group trials in Japan (in this analysis, the Japan Multinational Trial Organization LC03) & the US (SWOG 0003), 2) provide the basis for global standardization in clinical trials in NSCLC, and 3) facilitate regulatory changes needed for joint Japan-US studies. We performed a planned comparative analysis of the paclitaxel/carboplatin arms from LC03 & S0003, which had identical doses and schedules of paclitaxel dose (225mg/m2) and carboplatin (AUC 6). Conclusions: 1) This common arm analysis, as in our prior FACS-S003 report, shows great similarities in patient demographics between the LC03 and S0003. 2) Variable toxicities may be due to population-related pharmacogenomics (increased neutropenia & febrile neutropenia in LC03), and could be explained by polymorphisms in cytochrome P450 for paclitaxel metabolism (ongoing analysis). 3) Survival is increased in LC03. 4) Future joint Japan-US clinical trials should assess possible pharmacogenomic differences in drug disposition.

[Table: see text]

No significant financial relationships to disclose.

Bevacizumab (B) plus erlotinib (E) for patients (pts) with recurrent ovarian (OC) and fallopian tube (FT) cancer: Preliminary results of a multi-center phase II trial

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Background: The epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) are commonly over-expressed in OC and correlate with poor prognosis. The anti-VEGF antibody B and the EGFR tyrosine kinase inhibitor E have each demonstrated activity in OC. Dual inhibition with BE may overcome mechanisms of resistance encountered with either agent alone. Methods: We are conducting a 2-stage phase II trial of BE in pts with recurrent OC, primary peritoneal, and FT cancer. Eligible pts had ≤ 2 prior chemo regimens for recurrent or refractory disease; no prior VEGF or EGFR inhibitors; ECOG performance status (PS) 0–2; measurable disease; normal organ function; no proteinuria (<1000 mg/24 hours). B 15 mg/kg was given IV on day 1 every 21 days and daily E 150 mg PO was given continuously. CT scans were obtained every 9 weeks. 2 responses are required in the first stage to justify accrual into a second stage. Results: 13 pts enrolled at 3 centers from 7/05 to 10/05. Median age: 56 (range 45–70). PS (N with 0/1/2): 6/4/3. Primary site (N): OC 11, FT 2. Primary platinum response (N): refractory 4, resistant (<12 mo PFS) 2, sensitive (≥12 mo) 7. Total prior chemo regimens (N with 1/2/3): 1/8/4. 55 cycles of BE have been delivered (median 4, range 1–8). 12 pts are evaluable for response (1 too early). There has been 1 major response (8%). 8 patients (67%) had stable disease (SD). 1 pt with SD met 75% CA-125 response criteria. 8 pts remain on study. Median PFS has not been reached (median f/u 2.2 months). Attributable toxicities (N with grade 1/2/3/4): rash 4/7/0/0, diarrhea 6/1/2/0, stomatitis 3/1/0/0, myalgias 4/0/0/0, proteinuria 3/0/0/0, bilirubin 0/2/0/0. There were 2 bowel perforations (grade 3/4): both had 2 prior regimens, peritoneal implants >1 cm, 3 doses of B (last was 10 and 42 days prior), and small bowel obstructions in the preceding 28 days. Conclusions: The first stage of accrual is complete and further enrollment is on hold pending continued efficacy evaluation. There appeared to be an increased rate of bowel perforation, and identification of potential risk factors for this event would be critical for further development of this combination. Updated results will be presented. Supported by NCI Grant N01-CM-17102.

[Table: see text]

Bortezomib + gemcitabine (Gem)/carboplatin (Carbo) results in encouraging survival in advanced non-small cell lung cancer (NSCLC): Results of a phase II Southwest Oncology Group (SWOG) trial (S0339)

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Background: Bortezomib (PS-341), a small molecule proteasome inhibitor, has single agent activity in NSCLC and potentiates Gem/Carbo in pre-clinical models in a sequence-specific manner (Mortensen, Cancer Chem Pharm, 2004). A phase I trial of Gem/Carbo + PS-341 in patients (pts) with advanced NSCLC yielded an encouraging response rate of 48%. Here we describe the results of a SWOG phase II study of this regimen in advanced NSCLC. Methods: 114 eligible chemonaive stage IV and selected stage IIIB (pleural effusion) NSCLC pts received Gem 1000 mg/m2 on days 1, 8 and Carbo AUC 5 on day 1, followed 1 hour later by PS-341 1.0 mg/m2 on days 1, 4, 8, 11, with cycles repeated every 3 weeks. Non-progressing pts could continue PS-341 alone after 4 cycles. Results: Pt characteristics: Median age: 64 years; Sex M/F = 68/46; Performance status 0/1 = 50/64; stage IIIB/IV = 13/101. Response rate: 20% (95% CI 13–29%); 66% (95% CI 56–75%) had stable disease. At a median follow-up of 13 months, progression free and median survival times were 5 months (95% CI 3.5–5.3) and 11 months (95% CI 8.2–12.5). One-year survival was 46% (95% C.I. 37–55%). Most common grade 3/4 toxicities: neutropenia (52%), thrombocytopenia (63%), and fatigue (13%). Ongoing correlative studies are examining markers of proteasome inhibition (Bcl2 family, NFKB, IKB) and hypoxia (PAI-1, VEGF, OPN, HIF-1) in tumor tissue and surrogate specimens. Conclusions: The 11 month median survival achieved with the addition of PS-341 to Gem/Carbo in this phase II study is unprecedented in prior SWOG trials in advanced NSCLC, and does not appear to be explained by altered patient characteristics. The toxicity profile of this regimen is favorable. A phase III trial of Gem/Carbo ± Bortezomib in advanced stage NSCLC is under development. Supported by CA38926, CA32102.

No significant financial relationships to disclose.

Predicting clinical benefit from EGFR TKIs: Not all EGFR mutations are equal

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Background: EGFR mutations are associated with better response and in some studies (mainly Asian) also with prolonged survival after gefitinib therapy in patients with advanced NSCLC. Although a number of mutations have been reported, most frequent are exon 19 or exon 21 mutations of the EGFR tyrosine kinase domain.Whether clinical outcomes differ by subtype of EGFR mutation has not been previously reported. Methods: Mutation analysis (as previously described) was performed in 157 of 204 patients with advanced NSCLC treated with gefitinib (250 mg or 500 mg) in 2 study cohorts (Italian study of Iressa Expanded Access Program and SWOG 0126). Fifty nanograms of genomic DNA was isolated from pretreatment tumors, amplified for EGFR exons 19 and 21 by touchdown hemi-nested polymerase chain reaction and sequenced in both sense and antisense directions. Results: EGFR mutations were found in 43 pts (27%). Overall, patients with EGFR mutations had a response rate of 39% versus 7% for those without (p ≤ 0.001), disease control rate of 52% versus 37% (p = 0.14), time to progression of 3 months in both groups and median survival of 13 months versus 11 months (p = 0.14). Patients with exon 19 mutations exclusively (N = 11) had better outcome than those with exon 21 mutations exclusively (N = 31), with response rates of 67% versus 20% (p = 0.02), median time to progression of 15 months versus 2 months, and median survival of 26 months versus 10 months. There was a difference in time to progression (11 months versus 3 months) and overall survival (median 26 months versus 11 months) between patients with and without exon 19 mutations, while no difference was apparent in these outcome measures in patients with and without exon 21 mutations. Sample size provided insufficient power for significance tests of differences in survival outcomes. Conclusions: Not all EGFR mutations are created equal. Mutations in exon 19 are more predictive of response and survival after gefitinib than exon 21 mutations.

[Table: see text]

Alternative measures predicting clinical benefit in advanced non-small cell lung cancer (NSCLC) from Southwest Oncology Group (SWOG) randomized trials: Implications for clinical trial design

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Background: Although objective response (CR/PR) & overall survival (OS) are typical efficacy measures for new treatments in advanced stage NSCLC, each has its limitations; e.g., some patients (pts) have no measurable disease or achieve only disease stabilization (SD) while OS is influenced by effective salvage therapies. Alternative methods of determining “clinical benefit” are needed. Methods: Pooled data from 984 pts entered onto 3 randomized SWOG trials of platinum-based chemotherapy (S9509: carbo/paclitaxel (CP) vs. cisplatin/vinorelbine; S9806: carbo/gemcitabine ->P or cisplatin/vinorelbine -> docetaxel; & S0003: CP ± tirapazamine) were analyzed for survival using the Landmark method. Results: Pt characteristics: median age = 62 years; male sex = 647 pts (66%); stage IV = 826 pts (84%); weight loss ≥ 5% = 404 pts (42%); performance status (PS) 0/≥1 = 340 (36%)/606 (64%). Tumor response was seen in 260 pts (26%). Median time to response (TTR), time to progression (TTP) & OS were 1.9, 4.3 and 8.9 months. PS > 0 & weight loss were associated with worse survival (hazard ratio [HR] 1.38 and 1.28; p 0 (HR 0.75, p=0.03) and weight loss (HR 0.74, p = 0.03). Shorter TTP was associated with PS>0, stage IV, & weight loss (HR 1.34, 1.08, 1.34 and p = 0.0001, 0.01, < 0.00001). Of 886 pts alive at month 2 (time of initial response assessment following 2 treatment cycles), 62% had SD while19% had CR/PR for a disease control rate (CR+PR+SD, aka DCR) of 81%; 18% had progressive disease (PD). Although CR/PR at month 2 was associated with longer survival (HR 0.62, p<0.001), DCR had a much stronger association (HR 0.38, p<0.0001). Inclusion of DCR in the regression model improved its fit (p<0.00001), reducing the significance of CR/PR as an independent variable. Median survival among pts with CR/PR, SD, & PD were 13.5, 8.4, & 3.1 months. Conclusions: 1)DCR at month 2 is a more powerful predictor of subsequent survival than the CR/PR rate. 2) If validated, this “early look” statistical measure could enhance efficacy assessment. 3) These findings may have broad implications for the design of future trials in advanced NSCLC & will be prospectively tested in SWOG.

No significant financial relationships to disclose.

Advanced bronchioloalveolar carcinoma: a phase II trial of paclitaxel by 96-hour infusion (SWOG 9714): a Southwest Oncology Group study

BACKGROUND

There are no published prospective trials of chemotherapy for advanced bronchioloalveolar carcinoma (BAC), a subtype of non-small-cell lung cancer for which there is no current standard therapy. This phase II study assesses the efficacy and toxicity of 96-h paclitaxel in chemotherapy-naive patients with advanced BAC.

PATIENTS AND METHODS

Patients with histologically confirmed stage IIIB (with pleural effusion) or stage IV BAC were eligible. Treatment consisted of paclitaxel 35 mg/m2/24 h continuously infused over 96 h (days 1-4) every 21 days for up to six courses.

RESULTS

A total of 58 eligible patients were enrolled. The objective response rate was 14% (all partial responses, 9% confirmed); 40% of patients demonstrated stable disease. The median progression-free and overall survivals were 5 and 12 months, respectively. Grade 3 or greater toxicities included neutropenia/granulocytopenia (43%), febrile neutropenia (12%), infection (22%), and stomatitis/pharyngitis (10%); there were five treatment-related deaths.

CONCLUSIONS

S9714 represents the first prospective multi-institutional cooperative group trial focusing on treatment outcomes in BAC. Studies targeting this population are feasible, and while first-line paclitaxel administered as a prolonged infusion is active in this setting, toxicities limits the utility of this regimen. S9714 serves as a historical control for BAC patients against which future therapeutic approaches can be compared.