Michael Tanaka

University of California, Davis, Davis, California, United States

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Publications (10)32.44 Total impact

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    ABSTRACT: Purpose: Erlotinib marginally improves survival when administered continuously with gemcitabine to patients with advanced pancreatic cancer; however, preclinical data suggest that there is antagonism between chemotherapy and epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors when these are delivered concurrently. We tested a pharmacodynamic separation approach for erlotinib plus gemcitabine and interrogated EGFR signaling intermediates as potential surrogates for the efficacy of this strategy. Methods: Patients with measurable, previously untreated locally advanced unresectable or metastatic pancreatic cancer were treated with gemcitabine 1000 mg/m(2) as an intravenous infusion over 30-min on days 1, 8, 15 and erlotinib 150 mg/day on days 2-5, 9-12, 16-26 of each 28-day cycle. The primary endpoint was progression-free survival (PFS); secondary endpoints included RECIST objective response rate (ORR) and safety. The study was terminated after thirty patients due to funding considerations. Results: The median PFS was 2.07 months (95% CI; 1.87-5.50 months) and the ORR was 11%. No unexpected safety signals were seen: the most common grade 3 or higher adverse events were neutropenia (23%), lymphopenia (23%), and fatigue (13%). Patients with mutant plasma Kirsten rat sarcoma virus (KRAS) had significantly lower median PFS (1.8 vs. 4.6 months, p = 0.014) and overall survival (3.0 vs. 10.5 months, p = 0.003) than those without detected plasma KRAS mutations. Conclusions: Although pharmacodynamically separated erlotinib and gemcitabine were feasible and tolerable in patients with advanced pancreatic cancer, no signal for increased efficacy was seen in this molecularly unselected cohort. Detection of a KRAS mutation in circulating cell-free DNA was a strong predictor of survival.
    International Journal of Clinical Oncology 08/2014; 20(3). DOI:10.1007/s10147-014-0730-2 · 2.13 Impact Factor
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    ABSTRACT: Cetuximab is a chimeric monoclonal antibody targeting the epidermal growth factor receptor (EGFR). The recommended dosage is an initial load of 400 mg/m² intravenously (IV) followed by a weekly maintenance dose of 250 mg/m². It has been reported retrospectively that cetuximab efficacy was correlated with dose-related severity of skin rash. This study was prospectively designed to examine the safety and feasibility of escalating weekly doses of cetuximab, testing the hypothesis of the relationship of dose-dependent skin toxicity and efficacy. Methods Four dose levels were tested: Cetuximab 400 mg/m² IV loading dose and 250, 300, 350, 400 mg/m² weekly IV maintenance. There was no intra-patient dose escalation. Standard dose limiting toxicity criteria were used. Rash was evaluated using two additional validated dermatology methods: global acne grading scale (GAGS) and acne lesion counting (ALC). Tumor specimens and blood samples were obtained for correlative analyses. Twenty seven patients with solid tumors were enrolled: five head and neck, three pancreas, four gall bladder, two each of prostate, breast, colorectal, lung, and esophagus, and five others. Planned dose escalation was completed without reaching dose-limiting toxicity (DLT) or the maximum tolerated dose (MTD). The highest dose level was expanded to a total of 17 patients. Gr 3/4 toxicities included: lymphopenia (2), fatigue (2), and hypomagnesemia (2). One patient experienced a grade 3 rash (350 mg/m²). Sixty five percent of pts had a ≥ Gr 2 rash that was not dose dependent. In 22 evaluable patients, there was one partial response (PR) in a patient with cholangiocarcinoma (400 mg/m²) and seven patients had stable disease (SD). ALC and GAGS demonstrated no correlation with dose or response. Correlative studies evaluating k-ras, EGFR FISH status and immunologic correlatives were conducted on available tumor samples. Cetuximab administered at 400 mg/m² IV as a loading dose with weekly maintenance dose of 400 mg/m² is feasible and well tolerated. There was no direct correlation of the grade of rash with dose in this group of patients with heterogenous solid tumors.
    Investigational New Drugs 02/2010; 29(4):680-7. DOI:10.1007/s10637-010-9396-4 · 2.92 Impact Factor
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    ABSTRACT: To evaluate the response to lapatinib, an inhibitor of epidermal growth factor receptors 1 and 2, in patients with advanced bilary tree cancer (BTC) and hepatocellular cancer (HCC). Lapatinib was dosed at 1,500 mg/day orally continuously. Fifty-seven patients were accrued (BTC 17, HCC 40). Therapy was well tolerated. The response in BTC was 0% and in HCC was 5%. The progression free survival (PFS) for BTC and HCC patients was 1.8 (95% CI: 1.7-5.2) months and 2.3 (95% CI: 1.7-5.6) months. The median survival for BTC and HCC patients was 5.2 (95% CI 3.3-infinity) months and 6.2 (95% CI: 5.1-infinity) months. EGFR genotyping indicated HCC patients with <20 repeats have the lowest PFS. The occurrence of any skin rash significantly prolonged PFS and survival. Lapatinib was well-tolerated. There was evidence of activity in HCC, but therapy with lapatinib did not meet the predefined efficacy rate.
    Cancer Chemotherapy and Pharmacology 09/2009; 64(4):777-83. DOI:10.1007/s00280-009-0927-7 · 2.77 Impact Factor
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    ABSTRACT: Preclinical studies have demonstrated anticancer synergism with the combination of inhibitors of topoisomerases I and II. A population-based phase I trial was conducted to determine a population-based maximum tolerated dose (pMTD) for combining 2 topoisomerase inhibitors, irinotecan and epirubicin. Two cohorts of patients with advanced solid tumors were enrolled: 27 patients had and 22 patients had not received prior chemotherapy. In each cohort, irinotecan and epirubicin were administered beginning at a predetermined dose level. The dose for each subsequent 21-day cycle was escalated or de-escalated within each patient based on the dose-limiting toxicity observed in the previous cycle and according to a predetermined schema of dose levels. An MTD was determined for each patient (iMTD) and the iMTDs were used to determine a pMTD for each cohort of patients. The most common dose-limiting toxicity included neutropenia (51%), asthenia (10%), diarrhea (8%), and nausea/emesis (4%). The iMTDs ranged from dose level -3 to dose level 6. For previously chemotherapy-treated patients, the pMTD was 100 mg/m2 of irinotecan and 50 mg/m2 of epirubicin. For chemonaive patients, the pMTD was 150 mg/m2 of irinotecan and 50 mg/m2 of epirubicin. We have determined the pMTD of irinotecan and epirubicin administered every 3 weeks using a population-based approach. The pMTD is recommended for conducting phase II trials.
    American journal of clinical oncology 06/2008; 31(3):226-30. DOI:10.1097/COC.0b013e3181605440 · 3.06 Impact Factor
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    ABSTRACT: Bortezomib and pemetrexed are approved anticancer agents with non-overlapping mechanisms of action and toxicity. We examined the safety and tolerability of pemetrexed in combination with two different schedules of bortezomib in patients with advanced solid tumors. Two separate dose-escalating arms (arm A and arm B) were conducted simultaneously. Patients received pemetrexed on day 1 (D1) (500-600 mg/m2 IV) every 21 days. In arm A, bortezomib was given twice weekly (0.7-1.3 mg/m2 on D1, 4, 8, and 11). In arm B, bortezomib was given weekly (1.0-1.6 mg/m2 on D1 and 8). We treated 27 patients on four dose levels in arm A and three dose levels in arm B. Tumor types included lung (n = 16), adenoid cystic carcinoma (n = 2), prostate (n = 2), sarcoma (n = 2), breast (n = 1), thymus (n = 1), head and neck (n = 1), and gastrointestinal(n = 2). Dose-limiting toxicities were seen in arm A only; grade 3 asthenia (n = 2), grade 3 transaminitis and dehydration (n = 1). The most common grade 3/4 toxicity was neutropenia. Of 26 evaluable patients, 2 patients had partial response (1 in arm A and 1 in arm B), 13 had stable disease (7 in arm A and 6 in arm B), and 11 had progression (6 in arm A and 5 in arm B). Of the 16 patients with non-small cell lung cancer, 2 (12.5%) had partial response and 9 had stable disease, for a disease control rate of 68.8%. Recommended phase II dose for arm A is pemetrexed 500 mg/m2 and bortezomib 1.3 mg/m2 twice weekly. For arm B, the recommended dose is pemetrexed 500 mg/m2, bortezomib 1.6 mg/m2 weekly. Pemetrexed with bortezomib is feasible and tolerable at recommended single-agent doses. Based on the observed efficacy, a phase II study in non-small cell lung cancer is warranted.
    Journal of thoracic oncology: official publication of the International Association for the Study of Lung Cancer 01/2008; 2(12):1112-6. DOI:10.1097/JTO.0b013e31815ba7d0 · 5.28 Impact Factor
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    ABSTRACT: Cisplatin-based chemoradiotherapy (CRT) has been a standard treatment for patients with locally advanced esophageal cancer. However, cisplatin is associated with significant toxicity. We conducted a phase II clinical trial of concurrent paclitaxel, carboplatin, and radiation with or without surgery as an alternative to the standard cisplatin-based CRT for localized and metastatic esophageal cancer. Fifty patients with esophageal cancer were enrolled: 16 patients with stage II, eight patients with stage III, and 26 patients with stage IV disease. Two thirds (67%) of patients had adenocarcinoma and one third (33%) with squamous histology. Patients with resectable disease were treated with paclitaxel 30 mg/m, twice weekly for 10 doses, carboplatin AUC (area under the curve) 1.5 weekly for five doses; and concurrent radiation, 1.8 Gy/day, for a total of 45 Gy, followed by esophagectomy. Without surgery, patients received an additional dose each of paclitaxel and carboplatin with concurrent radiation for a total of 50.4 Gy, followed by two consolidation cycles of paclitaxel (200 mg/m) and carboplatin (AUC 6). During CRT, common stage III/IV toxicities included nausea/emesis (19%), esophagitis (9%), and neutropenia (4%). For consolidation chemotherapy, neutropenia (23%), neuropathy (8%) and nausea/emesis (4%) were the most common stage III/IV side effects. After CRT, 26% had a complete response, 17% had a partial response, and 41% had stable disease. Ninety-one percent of patients had clinical improvement of dysphagia. With a median follow-up of 32 months, the median survival was 12 months for patients with metastatic disease, 44 months for localized disease treated with esophagectomy, and >44 months for localized disease treated with definitive CRT. The regimen of paclitaxel, carboplatin, and radiation with or without surgery is well tolerated with promising efficacy for patients with esophageal cancer.
    Journal of thoracic oncology: official publication of the International Association for the Study of Lung Cancer 02/2007; 2(2):153-7. DOI:10.1097/JTO.0b013e31802bff75 · 5.28 Impact Factor
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    ABSTRACT: Clinical trials are essential to improve cancer therapy, but only 3% of newly diagnosed adult cancer patients enroll annually. We previously conducted a prospective analysis of factors affecting trial accrual at the UC Davis Cancer Center between 1997 and 2000. It was found that the accrual rate was 14% and that patients with private insurance were significantly less likely than patients with government insurance to enroll, suggesting that fear of insurance denial was a barrier. In 2002, a new California law (SB37) required insurers to reimburse routine costs of care for cancer trials. To assess the impact of SB37 on accrual, we repeated our study using the same sur vey instrument. Oncologists seeing new patients at the UC Davis Cancer Center from August to November 2002 completed questionnaires that inquired about patient characteristics and eligibility, protocol availability, and patient willingness to participate. Physicians considered clinical trials for 55% (118/216) of patients, but trials were available for only 53% (62/118). Eligibility criteria were met by 82% (51/62). Of these, 69% (35/51) agreed to participate (vs 51% previously). No patient declined to participate because of insurance limitations (vs 8% previously). Furthermore, insurance type was no longer a significant factor in determining whether patients would enroll. This suggests that although the overall rate of accrual is only slightly increased after passage of SB37, patients may be more willing to enroll. Efforts to increase participation must include enhancing physician and patient awareness of SB37.
    The Cancer Journal 09/2004; 10(5):294-300. DOI:10.1097/00130404-200409000-00006 · 4.24 Impact Factor
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    ABSTRACT: A novel schema of intrapatient dose escalation was applied to determine a population-based maximum tolerated dose (pMTD) for irinotecan (CPT-11, Camptosar) and carboplatin (Paraplatin) in a phase I trial. A total of 74 patients with advanced solid tumors were enrolled with the following characteristics: men/women, 46/28; median age, 61 years; 51 patients with and 23 patients without prior chemotherapy; performance status of 0-1 (93%) and 2 (7%). Patients were started at dose level 1 with irinotecan at 200 mg/m2, and carboplatin at an area under the concentration-time curve (AUC) of 5 mg/mL x min, administered every 21 days. Depending on degree of toxicity observed, the dose for each patient in each subsequent cycle was determined according to a predetermined schema of dose levels. Individual maximum tolerated dose (iMTD) was determined for each patient. The pMTD was defined as the highest dose level for which the incidence of dose-limiting toxicity occurred in less than 33% of the patient population. The most common dose-limiting toxicity included neutropenia (58%), thrombocytopenia (15%), diarrhea (8%), and nausea/emesis (7%). The iMTD ranged from dose level-3 (irinotecan at 100 mg/m2 and carboplatin at an AUC of 4) to dose level 5 (irinotecan at 350 mg/m2 and carboplatin at AUC 6). The pMTD was determined to be dose level-1 and 1 for previously chemotherapy-treated and--untreated patients, respectively. Fifty-nine patients were assessable for response. Of note, a response rate of 40% was observed in 15 patients with relapsed small-cell lung cancer previously treated with platinum-based therapy. We recommend dose level 1 of irinotecan (200 mg/m2) and carboplatin (AUC 5) for chemotherapynaive patients, and dose level-1 of irinotecan (150 mg/m2) and carboplatin (AUC 5) for chemotherapy-treated patients in phase II trials.
    Oncology (Williston Park, N.Y.) 08/2003; 17(7 Suppl 7):11-6. · 2.32 Impact Factor
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    ABSTRACT: Gemcitabine and paclitaxel are chemotherapeutic agents with clinical antitumor activity in a broad range of malignant solid tumors. Because of preclinical synergy, unique mechanisms of action and resistance, and nonoverlapping toxicities, gemcitabine and paclitaxel combinations are attractive for testing in clinical trials. Prior weekly gemcitabine and paclitaxel regimens administered on a 28-day cycle have been limited by cumulative hematological toxicity on day 15, thus reducing the planned gemcitabine dose intensity. We therefore conducted a phase I trial of a 21-day schedule of weekly gemcitabine and paclitaxel to determine the tolerability, maximum tolerated dose (MTD), and preliminary estimates of efficacy of this regimen. Forty-one patients with advanced malignant solid tumors were accrued. Gemcitabine was given at a fixed dose of 1000 mg/m2 while paclitaxel was administered at an initial dose of 60 mg/m2, then escalated by 15 mg/m2 increments over seven dose levels to a prospectively planned maximum dose of 150 mg/m2. Both agents were infused intravenously on days one and eight every 21 days. At least three patients were enrolled per dose level. No intrapatient dose escalation was allowed. All patients were assessable for toxicity and 31 were assessable for response. The regimen was generally well-tolerated. Dose-limiting thrombocytopenia was observed in one patient at a paclitaxel dose of 135 mg/m2/week (dose level 6). After expansion of this dose level by 14 additional patients, no further dose-limiting toxicities were observed although one patient at dose level seven died of neutropenic sepsis after completing three cycles. There were eight partial responders for an overall response proportion of 26% (95% CI: 11, 41). Twelve patients (39%) had stable disease. This 21-day schedule of gemcitabine and paclitaxel is safe, well-tolerated, and active. The recommended phase II dose is gemcitabine 1000 mg/m2 and paclitaxel 150 mg/m2 on days one and eight every 21 days. The antitumor activity observed with this regimen warrants further investigation.
    Cancer Investigation 02/2003; 21(1):7-13. · 2.22 Impact Factor
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    ABSTRACT: Dexamethasone and histamine antagonists have been employed commonly as premedications for prophylaxis of hypersensitivity reactions (HSRs) to paclitaxel. Frequent premedications for weekly administration of paclitaxel are associated with added side-effects and extra cost. We analyzed our experience of HSRs to paclitaxel administered every 3-4 weeks, and designed a treatment algorithm to eliminate premedications in a majority of patients receiving weekly paclitaxel. The incidence of HSRs was analyzed retrospectively in patients who received 3-hr infusions of paclitaxel (135-225 mg/m2) every 3-4 weeks in our institution over a period of 5 years. On the basis of the results of this analysis, we designed a premedication schema for patients receiving weekly paclitaxel, 50-90 mg/m2/week, as follows: Thirty minutes prior to the first weekly dose of paclitaxel, patients received intravenously (i.v.) dexamethasone (10 mg), diphenhydramine (25 mg), and cimetidine (300 mg). If no HSRs occurred, all premedications were deleted for subsequent weekly paclitaxel doses. For patients who experienced HSRs, 20 mg of dexamethasone was given orally 12 and 6 hr prior to re-challenge with paclitaxel in addition to diphenhydramine and cimetidine. Over a period of 5 years, 358 patients received 1608 3-hr infusions of paclitaxel (135-225 mg/m2). Hypersensitivity reactions, which occurred exclusively during the first cycle of paclitaxel administration, were observed in 14 patients. Of these 14 patients, 11 were successfully retreated with paclitaxel without HSRs, two had recurrent HSRs upon paclitaxel re-challenge, and one refused further treatment. These observations indicate that HSRs to paclitaxel occurred in 4% of patients upon first exposure, that most of these patients can be retreated successfully with paclitaxel without recurrent HSRs, and that if no HSRs occur during the first cycle, HSRs are unlikely to occur with subsequent paclitaxel administration. The premedication schema was applied to 30 patients receiving 205 one-hr infusions of weekly paclitaxel. Using this premedication strategy, no HSRs have been observed during the initial or subsequent administration of paclitaxel. We conclude that this premedication strategy is feasible and worthy of further study for patients receiving weekly paclitaxel.
    Cancer Investigation 02/2002; 20(5-6):666-72. DOI:10.1081/CNV-120003535 · 2.22 Impact Factor

Publication Stats

181 Citations
32.44 Total Impact Points


  • 2004–2010
    • University of California, Davis
      Davis, California, United States
  • 2009
    • California State University, Sacramento
      Sacramento, California, United States
  • 2002
    • CSU Mentor
      Long Beach, California, United States