Effect of BRAFV600E on response to sorafenib in advanced thyroid cancer patients

6002

Background: We are conducting an open-label phase II study of sorafenib in patients with metastatic, iodine-refractory thyroid carcinoma. Methods: 55 Patients were administered sorafenib 400 mg orally BID. Responses were monitored by PET and CT. Primary endpoints were response rate (RR) and progression free survival (PFS) by RECIST criteria. BRAF and RAS mutation status is determined by DNA sequencing. Outcome data is evaluated using the Kaplan-Meier method and log-rank test. Biologic activity in tissue obtained during treatment at response and progression is being explored using immunohistochemistry (IHC) to pERK, pAKT and Ki-67 among others, in pretreatment blocks from virtually all patients, and a subset of 14 patients in whom on-treatment tissue is available. Results: We have completed accrual of the 55 patients planned for enrollment; median time on study is 34 weeks and 25 pts (45%) are male. Histological subtypes include papillary (PTC): 25 pts (47%); follicular/Hürthle Cell (FTC): 19 pts (36%); medullary: 4 pts (8%), and poorly differentiated/anaplastic: 5 pts (9%). 52/55 patients are evaluable for response at this time. Median PFS was 84 wks. Genotyping of BRAF is complete in 16 patients. For patients with PTC/FTC, the PFS for those with BRAFwt was 54 wks compared to 84+ wks for patients with BRAFV600E (p = 0.028). On-treatment tissue at progression demonstrates heterogeneity, with p-ERK and p-AKT suppressed in some areas, but highly expressed in others. Data at 6 months post accrual of the last patient will be presented along with patient thyroglobulin levels, PET and CT scans. IHC and additional genotyping will also be presented. Conclusions: Sorafenib has activity in patients with advanced thyroid cancer with an overall PFS of 84 wks. While most patients with PTC or FTC achieve durable responses, patients whose tumors harbor BRAFV600E have significantly longer PFS than those that are BRAFwt.

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Sorafenib targets BRAF and VEGFR in metastatic thyroid carcinoma

6019

Background. There is no effective therapy for patients with metastatic thyroid cancer not cured by surgery or treatment with I131. Sorafenib is a promising multi-tyrosine kinase inhibitor for patients with metastatic PTC (mPTC). Although the primary targets of sorafenib are thought to include BRAF and VEGFR, this has been the subject of debate. Whether sorafenib primarily acts on the tumor cells (TC) or endothelial cells (EC) and how BRAF mutation status (45% of PTC harbor V600E) relates to response is also unknown. Methods. Responses of patients with metastatic, iodine-refractory PTC, enrolled into our phase II study of sorafenib were monitored by PET at 4 wks and CTs every 2 mos. Sorafenib activity was studied using immunohistochemistry (IHC) for pERK, pAKT, and pVEGFR-2, while Ki-67 showed proliferating cells in tumor tissue pre- and on treatment. BRAF mutation status was determined by DNA sequencing. Results. Of 15 patients, five patients achieved a PR, three are stable (SD), two progressed, and three patients with SD withdrew due to toxicity. Target lesions decreased on average 31%. Eight of 10 PET scans showed decreased activity at 4 weeks. IHC on tissue from 2 patients (at 1 and 2 wks, both BRAFwt) showed 50% decrease in pERK (downstream of VEGFR2 and BRAF) and 30% decrease in pAKT (downstream of VEGFR2). p-ERK and p-AKT were altered in both the TC and EC. Ki-67 decreased from 10% to <1%. No change in VEGFR-2 was seen; but, pVEGFR-2 completely disappeared in one sample while the other showed a small decrease. Quantitative analysis using a multispectral imaging system confirmed the changes observed by IHC. In tissue from a patient at 17 months on sorafenib, the decrease in pERK and pAKT appeared to be the same or reversed, suggesting compensatory changes in these pathways in resistant but stable disease. Conclusions. Our study shows the early clinical and biologic activity of sorafenib in patients with mPTC and the targets of early suppression. Importantly, it also reveals compensatory changes in target molecules in cells resistant to therapy. These cells are the likely source of tumor resistance that has been seen to develop to other similar targeted agents. Sorafenib is the first viable treatment option for patients with mPTC, and these results provide key insights into the mechanisms of action and resistance of this drug.

No significant financial relationships to disclose.

Sorafenib combined with carboplatin/paclitaxel for advanced non-small cell lung cancer: A phase I subset analysis

7194

Background: The EGFR is often overexpressed in advanced non-small-cell lung cancer (NSCLC) - a solid tumor associated with a poor prognosis. Oncogenic k-ras mutations and raised serum VEGF predict poor outcome in NSCLC. In vitro targets of sorafenib include Raf, which is downstream of EGFR and k-ras. Sorafenib also targets the VEGFR-2/-3 tyrosine kinases, involved in tumor angiogenesis. Preclinically, sorafenib targets the tumor and tumor endothelium to inhibit tumor growth. Methods: This subanalysis of a Phase I trial with a Phase II expansion in NSCLC was performed to evaluate the safety (adverse events graded by NCI-CTC 2.0) and preliminary anti-tumor activity (response by RECIST, PFS, TTP) of oral sorafenib combined with carboplatin/paclitaxel in 15 patients with advanced, progressive NSCLC. Carboplatin (AUC 6)/paclitaxel (225 mg/m2) was administered on Day 1, and sorafenib (100, 200, or 400 mg bid) on Days 2–18 of each 21-day treatment cycle. Results: Drug-related adverse events were reported by 73% (11/15) of patients, but were mostly grade 1–2 (53%) in severity; none was grade 4. The most common drug-related events at any grade were dermatologic (Hand-foot skin reaction [20%]; rash [60%]), and gastrointestinal (diarrhea [20%]; anorexia [13%]). There were no drug-related cardiovascular adverse events. Three patients reported grade 1–2 drug-related bleeding events (epistaxis n = 2; other n = 1). Of the 14 evaluable patients, four (29%) had a confirmed PR as best response, seven (50%) had SD, and three (21%) had PD. Therefore, the disease control rate (objective response plus SD) was 79%. Duration of response was 25 weeks. Median PFS was 34 weeks. Discussion: This sorafenib combination was well tolerated and showed promising preliminary anti-tumor activity in patients with advanced, progressive NSCLC.

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Phase I trial of UFT/leucovorin and irinotecan in patients with advanced cancer

UFT (BMS-200604, Uftoral) is an oral fluoropyrimidine that combines uracil and the 5-fluorouracil (5-FU) prodrug, ftorafur, in a 4:1 molar ratio with single-agent activity in breast and gastrointestinal cancers. In vitro studies have shown that irinotecan downregulates thymidylate synthase (TS) expression in tumour cells, leading to synergy between irinotecan and 5-FU that is maximal when irinotecan is given 24 h prior to 5-FU. Given this observed synergy and the confirmatory clinical activity of combination therapy with 5-FU, leucovorin (LV) and irinotecan, we performed a phase I trial to determine the maximum tolerated doses (MTD) of UFT, LV, and irinotecan. Treatment consisted of irinotecan administered as a 90-min intravenous (i.v.) infusion on day 1 followed by twice daily oral UFT/LV on days 2-15, repeated every 21 days. Initial doses were irinotecan 200 mg/m(2) and UFT 200 mg/m(2)/day, with LV dose fixed at 60 mg/day. 31 patients received a total of 130 cycles of UFT/LV and irinotecan. 3 of 9 patients experienced grade 3/4 diarrhoea at the highest dose level of irinotecan 310 mg/m(2) and UFT 300 mg/m(2)/day. Other toxicities included neutropenia, anaemia, alopecia, nausea/vomiting and fatigue. Further dose escalation was not pursued since this level of toxicity was appropriate for future phase II study. One patient with colorectal cancer experienced a partial response and 9 patients with non-small cell lung, colorectal and gastro-oesophageal junction carcinomas had disease stabilisation lasting 4-26 (median 6) cycles. Methylenetetrahydrofolate reductase (MTHFR) C677T genotype was analysed in peripheral mononuclear cells (PMNs) obtained from 24 patients. 2 patients had the homozygous TT polymorphism and 1 of them had grade 3 diarrhoea at the first dose level. Irinotecan on day 1 followed by a 14-day course of oral UFT/LV beginning on day 2 is well tolerated, and suitable for testing in several tumour types. Doses recommended for further study on this schedule are irinotecan 310 mg/m(2) and UFT 300 mg/m(2)/day, with LV 60 mg/day.

Phase I clinical and pharmacogenetic trial of irinotecan and raltitrexed administered every 21 days to patients with cancer

PURPOSE

Irinotecan and raltitrexed display schedule-dependent synergy in vitro, which supports the clinical investigation of the combination. Functional polymorphisms of the methylenetetrahydrofolate reductase (MTHFR) gene result in intracellular redistribution of folate derivatives, which may affect raltitrexed-associated cytotoxicity.

PATIENTS AND METHODS

Patients with a range of solid cancers and good performance status received irinotecan as a 90-minute infusion on day 1 and raltitrexed as a 15-minute infusion on day 2, repeated every 21 days. Samples were collected for MTHFR C677T genotyping and fasting plasma homocysteine during the first cycle.

RESULTS

Thirty-nine assessable patients received 127 cycles of therapy. Irinotecan doses ranged from 100 to 350 mg/m(2), and raltitrexed, 1.0 to 4.0 mg/m(2). Raltitrexed doses of more than 3.0 mg/m(2) were not tolerated and were associated with dose-limiting asthenia, diarrhea, and AST/ALT elevation. Irinotecan/raltitrexed doses of 350/3.0 mg/m(2) were well-tolerated; principal toxicities included neutropenia, diarrhea, and fatigue. Two partial responses were observed in patients with pretreated gastroesophageal cancers. Homozygotes with the MTHFR 677 TT polymorphism incurred significantly less raltitrexed-associated toxicity than those with either wild-type or heterozygous genotypes (P = .05). No significant differences were noted in plasma homocysteine values between the genotypic subtypes, and plasma homocysteine levels did not predict the risk of toxicity.

CONCLUSION

Irinotecan and raltitrexed doses of 350 and 3.0 mg/m(2) are recommended for further study on a day 1, 2 schedule every 21 days. Efficacy results suggest that trials in upper and lower gastrointestinal malignancies are warranted. MTHFR C677T genotypes may be predictive of clinical raltitrexed toxicity.

Irinotecan and UFT/leucovorin in patients with advanced cancers

The combination of irinotecan and fluorouracil (5-FU) is synergistic when applied to human colon cancer cell lines in vitro and appears to be schedule-dependent: maximal activity occurs when irinotecan is administered prior to 5-FU. In this phase I study, irinotecan is administered in combination with UFT and leucovorin in patients with advanced solid tumors. Irinotecan is given as a 90-minute intravenous infusion on day 1 followed by twice-daily UFT plus oral leucovorin on days 2 through 15. Cycles are repeated every 21 days. Five patients have been treated to date; four are evaluable for toxicity. Starting doses were irinotecan 200 mg/m2/day, UFT 200 mg/m2/day, and leucovorin 60 mg/day. Preliminary results indicate that irinotecan in combination with UFT plus leucovorin is well tolerated at the initial doses (described in this article).