Failure Of Tyrosine Kinase Inhibitors Research Articles

Abstract A27: PI3K/Akt pathway-dependent and -independent mechanisms of resistance to EGFR tyrosine kinase inhibitors in glioblastoma

Abstract EGFR-targeted therapies such as the tyrosine kinase inhibitors (TKIs) gefitinib and erlotinib have had limited success clinically for the treatment of glioblastoma (GBM). Interestingly, some of the most common mechanisms of resistance to these agents in other solid tumors are rarely present in GBM. In an effort to identify and characterize molecular mechanisms of acquired resistance to EGFR TKIs in GBM, we utilized TKI-sensitive, transformed ink4a/arf −/− astrocytes overexpressing the constitutively active mutant ΔEGFR (or EGFRvIII). To model TKI-resistance in vitro, cells were seeded in soft agar in the presence of gefitinib or erlotinib for 2 weeks; during this time, colony formation was inhibited by TKIs. The dose was escalated, and after 3 weeks, TKI-resistant colonies began to emerge and were isolated to generate clonal cell lines. TKI resistance was verified in vitro as well as in vivo using an orthotopic intracranial model. In three clonally derived TKI-resistant lines, ΔEGFR expression was not altered, and gefitinib inhibited receptor phosphorylation. Two of these three cell lines demonstrated decreased PTEN expression and increased, sustained Akt phosphorylation, indicating a failure of TKIs to suppress signaling through the oncogenic PI3K/Akt pathway. Importantly, this phenotype mimics a known mechanism, as PTEN loss has been implicated in resistance to EGFR TKIs in GBM. The third TKI-resistant cell line had no change in PTEN expression, and Akt phosphorylation was completely inhibited by gefitinib. Interestingly, TKI-resistance was irreversible in those cells with decreased PTEN, and reversible in cells having no change in PTEN expression. In fact, resensitized cells demonstrated ΔEGFR and ERK phosphorylation that was several-fold greater than that of parental cells, as well as increased sensitivity to gefitinib and erlotinib. Interestingly, autophagy was dramatically elevated in all of these TKI-resistant lines, and the cell line that was resensitized to TKIs displayed a significant reduction in autophagy compared to its resistant counterpart. Overall, we have generated and characterized a model system for the identification of mechanisms of resistance to EGFR TKIs in GBM. We have identified at least two distinct resistance scenarios in cells with wild-type PTEN: an irreversible mechanism involving decreased PTEN expression, and another mechanism that is reversible and does not appear to directly involve the PI3K pathway. These findings suggest that reversibility of TKI-resistance following drug removal may depend on mechanism of resistance, which has potential clinical implications. Moreover, the fact that increased autophagy is a common feature suggests a potential therapeutic opportunity for targeting the autophagic process that may apply despite apparent differences in molecular mechanism. This work forms the basis for our effort to uncover novel targets or approaches to therapy that may increase the utility of these drugs for treatment of GBM.

Chromophobe renal cell carcinoma with prolonged response to targeted therapy: a case report

IntroductionChromophobe renal cell carcinoma is universally accepted as a distinct subtype of renal cell carcinoma. There are conflicting reports on prognosis, and few data on response to treatment exist. Currently, we do not have any effective treatment for the metastatic disease apart from surgical procedures. Current strategies are based on results obtained in the context of clear cell-type renal cell carcinoma. Separate trials for rare histologies seem unfeasible and are unlikely to be performed. For these cases, clinical observations are an important part for advancing therapeutic insight. In recent years, novel tyrosine kinase inhibitors have been shown to have significant clinical benefit in advanced renal cell carcinoma.Case presentationWe present the case of a 43-year-old Caucasian man with advanced chromophobe renal cell carcinoma treated with the tyrosine kinase inhibitor sunitinib and subsequently with sorafenib and the mammalian target of the rapamycin inhibitor everolimus, achieving a prolonged response and significant clinical benefit. We report an unexpectedly high efficacy of everolimus as a third-line treatment in a patient with metastatic chromophobe renal cell carcinoma.ConclusionsUp to now, no published data from randomized clinical studies have addressed the question of efficacy of everolimus as a third-line treatment after failure of tyrosine kinase inhibitors. To the best of our knowledge, this case is the first report of chromophobe renal cell carcinoma treated successfully with sequential tyrosine kinase and mammalian target of rapamycin inhibitor therapy. Notably, the time on treatment with sunitinib exceeded four years. The case presented here implies that everolimus could be a viable option for patients with metastatic chromophobe renal cell carcinoma.

Abstract 3239: The Notch pathway as a new target in gastrointestinal stromal tumors

Abstract Small molecule kinase inhibitors have dramatically improved the survival of patients with Gastrointestinal Stromal Tumors (GIST), yet most patients develop resistance, urging us to understand better the molecular mechanisms underlying this disease and identify new therapeutic strategies. Notch signaling is a conserved developmental pathway known to play a critical role in the development of several cancers, functioning as a tumor promoter or a tumor suppressor. Given that the normal progenitor cell for GIST, the Interstitial Cell of Cajal, has characteristics similar to those of cells of neuroendocrine origin, we hypothesized that Notch pathway impacts the biology of GIST cells. In a previous study, we demonstrated that constitutively active intracellular domain of Notch1 (ICN-1) induced growth arrest in GIST cell lines. Here we report that ICN-1 downregulated KIT protein by a flow cytometric analysis in the three cell lines analyzed (GIST-T1, GIST882, GIST48IM). In parallel, inhibitions of Hes1, a major target gene of ICN-1, with a dominant negative construct, upregulated KIT protein expression in vitro (60% increase on western blot). This anti-tumor effect of Notch1 in GIST leads to a therapeutic opportunity as we showed in the present study that treatment with the histone deacetylase inhibitor, SAHA, caused a dose-dependent upregulation of Notch1 (6 fold increase of the mRNA with SAHA 2 µm/L on GIST-T1, P<0.05), downregulation of KIT and pKIT (9 fold decrease of pKIT on western blot with SAHA 2 µm/L on GIST-T1), increase in apoptosis (25-fold increase in the sub-G1 population with SAHA 2 µmol/L on GIST-T1, P<0.05), decrease in viability of the GIST cells (IC50 = 2 µmol/L on GIST-T1).To confirm the clinical relevance of the Notch pathway on GIST, we performed a retrospective analysis on 15 pre-treated patient tumors and showed that GIST patients with high Hes1 mRNA levels have a significantly longer relapse-free survival than the one with low Hes1 mRNA levels (median of 37 months for the low group versus median not reached at >80 months for the high group; P=0.005). These results identify a novel anti-tumor effect of Notch1 via a crosstalk between the Notch1 and KIT pathways in GIST cells. This finding may lead to new therapeutic strategies for GIST patients, in particular after failure of tyrosine kinase inhibitors. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3239. doi:1538-7445.AM2012-3239

Comparative efficacy of vascular endothelial growth factor (VEGF) tyrosine kinase inhibitor (TKI) and mammalian target of rapamycin (mTOR) inhibitor as second-line therapy in patients with metastatic renal cell carcinoma after the failure of first-line VEGF TKI

Sequential therapy is a standard strategy used to overcome the limitations of targeted agents in metastatic renal cell carcinoma. It remains unclear whether a mammalian target of rapamycin (mTOR) inhibitor is a more effective second-line therapy after first-line vascular endothelial growth factor tyrosine kinase inhibitor (VEGF TKI) has failed than the alternative, VEGF TKI. A clinical database was used to identify all patients with renal cell carcinoma who failed at first-line VEGF TKI and then treated with second-line VEGF TKI or mTOR inhibitors in the Asan Medical Center. Patient medical characteristics, radiological response and survival status were assessed. Of the 83 patients who met the inclusion criteria, 41 received second-line VEGF TKI [sunitinib (n = 16) and sorafenib (n = 25)] and 42 were treated with mTOR inhibitors [temsirolimus (n = 11) and everolimus (n = 31)]. After a median follow-up duration of 23.9 months (95 % CI, 17.8-30.0), progression-free survival was 3.0 months for both groups [hazard ratio (HR, VEGF TKI vs. mTOR inhibitor) = 0.97, 95 % CI 0.59-1.62, P = 0.92]. Overall survival was 10.6 months for the VEGF TKI group and 8.2 months for the mTOR inhibitor group (HR = 0.98, 95 % CI 0.57-1.68, P = 0.94). The two groups did not differ significantly in terms of disease control rate (51 % for VEGF TKI and 59 % for mTOR inhibitor, P = 0.75). Second-line VEGF TKI seems to be as effective as mTOR inhibitors and may be a viable option as a second-line agent after first-line anti-VEGF agents have failed.

Initial Progression-Free Survival after Non-First Line TKIs Therapy Potentially Guides Immediate Treatment after Its Failure in Advanced Non-Small Cell Lung Cancer.

ObjectiveThe standard therapy after failure of the initial non-first line epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) treatment in advanced non-small cell lung cancer (NSCLC) has not yet been established. The aim of the current study was to identify whether the 2nd TKI treatment or chemotherapy (paclitaxel-containing or non-paclitaxel regimen) is the appropriate treatment for patients with NSCLC based on the efficacy of the initial TKIs.MethodsSeventy-two advanced NSCLC patients who had accepted 2nd TKIs or chemotherapy immediately after failure of the initial TKIs in non-first line setting from May 1, 2004 to January 31, 2010 at the Sun Yat-sen University Cancer Center were enrolled. The primary endpoint [2nd progression-free survival (PFS)] and the second endpoint [overall survival (OS)] were compared among the 2nd TKI and chemotherapy groups as well as their subgroups.Results(1) Twenty-one patients were treated with 2nd TKIs, and 51 patients were administered chemotherapy after failure of the initial non-first line TKI treatment. There was nonsignificant difference in the responses (P=0.900) [2nd PFS (P=0.833) and OS (P=0.369)] between the 2nd TKI and chemotherapy groups. (2) In the 2nd TKI group, 9 patients exhibited PFS≥7 months. The initial TKI treatment group exhibited a longer 2nd PFS than the other 12 patients with an initial PFS<7 months (7 months vs. 2 months, P=0.019). However, these groups had nonsignificantly different OS (P=0.369). (3) In the chemotherapy group, patients with PFS<5 months exhibited longer 2nd PFS than those with PFS ≥ 5 months in the initial TKI treatment (3 months vs. 2 months, P=0.039). (4) In the chemotherapy group, patients treated with paclitaxel-containing regimen showed longer 2nd PFS than those treated with non-paclitaxel regimen (5 months vs. 2.3 months, P=0.043).ConclusionsPatients with PFS≥7 months or <5 months under the initial TKI treatment potentially benefit from the 2nd TKI treatment or chemotherapy immediately after failure of the non-first line TKIs. The paclitaxel-containing regimen may improve the 2nd PFS. However, more patient samples are urgently needed to validate these findings.

Transcatheter arterial chemoembolization for gastrointestinal stromal tumors with liver metastases.

To evaluate the efficacy and safety of transcatheter arterial chemoembolization (TACE) for gastrointestinal stromal tumor (GIST) with liver metastases after the failure of tyrosine kinase inhibitors (TKIs). Patients with histologically confirmed CD117-positive GIST with liver metastases who were resistant and/or intolerant to prior imatinib and/or sunitinib and who received TACE for at least one treatment cycle or only best supportive care and TKI reintroduction were eligible for the study. The patients were divided into two groups: those in TACE group received TACE treatment containing 5-20 mL iodized oil and 40-80 mg doxorubicin hydrochloride and TKI reintroduction or best supportive care, those in control group only received TKI reintroduction or best supportive care. The primary end-point was overall survival and the secondary end-points were, progression-free survival (PFS), response rates, and safety. Sixty patients admitted between June 2008 and October 2011 were eligible for this study, including 22 in TACE group and 38 in control group. In the TACE group, 12 (54.5%) achieved liver partial response, 5 (22.7%) had stable disease, and 5 (22.7%) had liver progressive disease. Disease control rate of liver metastases was 77.3% in the TACE group and 39.5% in the control group. The median liver PFS in TACE group was 47.1 wk (95% CI: 23.9-70.3). The median PFS in TACE group was longer than in control group (30.0 wk, 95% CI: 20.1-39.9 vs 12.9 wk, 95% CI: 11.9-13.9) (P = 0.0001). The median overall survival in TACE group was also longer than in control group (68.5 wk, 95% CI: 57.4-79.6 vs 25.7 wk, 95% CI: 23.2-28.2) (P = 0.0001). TACE treatment significantly reduced the risk of death (hazard ratio: 0.109). Patients without extrahepatic metastases treated with TACE had significantly better prognosis. Most of the adverse events were of grade 1 or 2 and tolerable. TACE is effective and well tolerated in GIST patients with liver metastases after TKI failure, and it may be an optional treatment for this disease.

Bevacizumab for glioblastoma refractory to vascular endothelial growth factor receptor inhibitors

Glioblastoma (GBM) is a highly vascular tumor dependent on angiogenesis through the vascular endothelial growth factor (VEGF) signaling cascade. Inhibition of VEGF signaling is an important therapeutic strategy. We report our experience with bevacizumab (BEV), a VEGF targeting antibody, following failure of a VEGF receptor targeting tyrosine kinase inhibitor (TKI). We retrospectively identified patients treated on clinical trials with VEGFR-TKIs for recurrent GBM followed by BEV at next recurrence. Survival was estimated by the Kaplan-Meier method. Fourteen patients were identified (six women; median age 57). All received VEGFR-TKIs (sunitinib 11, cediranib 2, sorafenib 1) then BEV at next recurrence. There were no radiographic responses to VEGFR-TKIs; best response was stable disease in 50% (7/14). Patients received BEV alone (21%, 3/14) or in combination with chemotherapy (79%, 11/14). On BEV, 29% (4/14) had a partial response, and 36% (5/14) stabilized. Of evaluable patients, 42% (5/12) had neurological improvement and 56% (5/9) reduced corticosteroid requirement. Median survival on BEV was 7.8 months (95% CI 4.0-15.8), median progression-free survival (PFS) was 4.0 months (95% CI 1.6-10.5), and the 6-month PFS rate was 29% (95% CI 9-52). Our radiographic and survival outcomes with BEV following progression after VEGFR-TKIs are similar to data from studies of BEV as initial salvage therapy, although our sample size was small. Prior exposure to VEGFR-TKIs may not preclude response to BEV, but sensitivity to BEV may be lower following more robust VEGFR inhibition.

Phase II escalation study of sorafenib in patients with metastatic renal cell carcinoma who have been previously treated with anti‐angiogenic treatment

To assess both clinical and biological efficacy and toxicity of sorafenib in patients with metastatic renal cell carcinoma (mRCC) previously treated with an anti-angiogenic vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitor. Sorafenib is an orally active multikinase inhibitor approved for the treatment of mRCC. Drug-focused translational research on tissues (i.e. B-RAF) and plasma (VEGFR-α, circulating endothelial cells, endothelial progenitor cells) was performed to define biological predictive and prognostic markers and their related kinetics. Patients with mRCC pretreated with an anti-angiogenic treatment, an Eastern Cooperative Oncology Group performance status (ECOG PS) of 0-2 and adequate organ function were eligible. Patients received sorafenib 400 mg twice a day continuously in 4-week cycles. Patients with no progressive disease at 12 weeks continued to receive sorafenib at the standard dose, whereas progressing patients received an increased dose (600 mg twice a day) with early disease restaging after 4 weeks. Patients who progressed at 600 mg twice a day went off study. Efficacy (overall tumour control) was assessed by Response Evaluation Criteria in Solid Tumors. In all, 19 patients were entered. The baseline characteristics were as follows: ECOG PS 0-1 94.8%; median (range) age 62 (41-81) years; nephrectomy 100%; surgery for metastatic disease 26.4%; clear cell 79.1%; papillary cell 15.7%; sarcomatoid/high grade 5.2%; two or more metastatic sites 84%. Overall, 11 patients (58%) had disease control at 6 months without significant correlation between response to prior therapy and hypertension. Progression-free survival (PFS) of 8.3 months was observed. Of six patients for whom the dose was escalated due to early progression, three benefitted with PFS of >3 months. Three (15.7%) of 19 patients had a V600E mutation and one had a K601E mutation; PFS appeared to be substantially shorter in these patients compared with 15 patients with wild-type B-RAF (2.5 vs 9.1 month, P < 0.05). The most common toxicity (National Cancer Institute Common Toxicity Criteria, NCIC 3.0, all patients) was grade ≥1 diarrhoea and grade 2-3 hand-foot syndrome in 11 patients. Grade 3 mucositis was observed in one patient. Sorafenib at doses of 400-600 mg twice a day continuously results in acceptable and well tolerated salvage treatment after VEGFR tyrosine kinase inhibitor failure. In progressive patients, treatment with a higher dose could be a valid option and B-RAF mutations may be an interesting predictive marker to be studied in a larger randomized trial.

Sequence Therapy in Patients with Metastatic Renal Cell Carcinoma: Comparison of Common Targeted Treatment Options Following Failure of Receptor Tyrosine Kinase Inhibitors

BackgroundThe best sequence of targeted therapy in patients with metastatic renal cell carcinoma (mRCC) has not been sufficiently defined. ObjectiveTo describe the efficacy and toxicity of sequential everolimus (EV) versus receptor tyrosine kinase inhibitor (rTKI) following failure of first rTKI treatment. Design, setting, and participantsRetrospective study of 108 patients receiving rTKI or EV after progression on rTKI therapy at two German academic centres. InterventionSequence of systemic targeted treatment with sunitinib (n=85) or sorafenib (n=23) followed by EV (n=62) or another rTKI (n=46; sorafenib, n=35; sunitinib, n=11). MeasurementsWe measured response rate (Response Evaluation Criteria in Solid Tumours 1.0) and toxicity. Survival analysis (Kaplan-Meier method and Cox regression) was conducted for progression-free survival (PFS) and overall survival (OS). Results and limitationsMain patient characteristics did not significantly differ by sequence of treatment groups (rTKI-rTKI vs rTKI-EV). Response rate following first rTKI failure was not significantly different between sequential therapies with a disease control rate of 51.6% (EV) and 43.5% (rTKI). The corresponding median PFS was 3.6 mo (95% confidence interval [CI], 1.8–5.4) for EV and 4.0 mo (3.2–4.9) for rTKI treatment. The estimated OS was longer for the rTKI-EV group (43 mo; 95% CI, 33.9–52.1) than for the rTKI-rTKI group (29 mo; 95% CI, 18.6–39.5; p=0.03), but this difference lost statistical significance in multivariable-adjusted analyses. Intrinsic rTKI resistance was independently associated with inferior subsequent PFS (hazard ratio [HR]: 1.79; 95% CI, 1.15–3.62; p=0.015) and OS (HR: 6.54; 95% CI, 3.01–14.20; p<0.001). Limitations are the retrospective design, limited numbers of cases, and residual confounding factors. ConclusionsThe sequence therapies rTKI-EV and rTKI-rTKI may be equally efficacious in terms of PFS and response rate, whereas a tendency towards superior survival was observed for the rTKI-EV sequence. These data, particularly the potential benefit of an early change of mode of action, need confirmation in randomised comparative trials.

Second-line sequential therapy in patients with metastasized renal cell carcinoma (mRCC): Retrospective comparison of common treatment options following failure of receptor tyrosine kinase inhibitor therapy.

e15059 Background: Everolimus (EV) is an efficacious treatment option after failure of receptor tyrosine kinase inhibitor (rTKI) therapy in mRCC patients. However, the best sequence of targeted therapy options has not been sufficiently defined. The objective of this study was to describe the clinical activity of sequence options in 2nd line treatment, i.e. rTKI followed by EV vs. rTkI followed by another rTKI. Methods: Retrospective study of 108 patients receiving rTKI or everolimus treatment after progression on first-line rTKI therapy at 2 German academic centres. Sequence of systemic targeted treatment consisted of an rTKI-rTKI-sequence (n=46; sunitinib-sorafenib, n= 35; sorafenib-sunitinib, n=11) or an rTKI-EV sequence (n=62). Median progression free survival (PFS) and median overall survival (OS) were determined for the two sequence treatment options using the Kaplan-Meier method. Response to treatment was assessed according response evaluation criteria in solid tumors (RECIST) 1.0. Results: Sequence treatement groups (rTKI-rTKI vs. rTKI-EV) did not significantyl differ by gender, MSKCC prognostic group, or ECOG performance status. Best response to 2nd line therapy included partial response (EV: n=2, 3%; rTKI: n=5, 11%; p=.11) and stable disease (EV: n=30, 48%; rTKI: n=15, 33%; p=.21) for a disease control rate of 51.5% (EV) and 43.4% (rTKI), respectively. The estimated 2nd line PFS was 3.6 months (92% CI: 1.8 – 5.4) for Everolimus and 4.0 months (3.2 – 4.9) for rTKI sequential therapy. The estimated OS was longer for the group of patients receiving the rTKI-EV sequence (43 months; 95% CI: 33.9 – 52.1) than for those receiving the rTKI-rTKI sequence (29 months, 95% CI: 18.6 – 39.5; p = .03). However, the rTKI-rTKI group was characterized by a relatively short first-line PFS (6.6 months compared to 10.6 months of the rTKI-EV group) which may at least in part explain the observed OS difference. Conclusions: Common sequence treatment options may have comparable efficacy in terms of PFS and response rate. The observed differences in OS await further confirmation in prospective randomized trials.

Sequential mTOR inhibitor treatment with temsirolimus in metastatic renal cell carcinoma following failure of VEGF receptor tyrosine kinase inhibitors

Agents targeting the mammalian target of rapamycin (mTOR) pathway, e. g. everolimus, can provide clinical benefit in pretreated patients with metastatic renal cell carcinoma (mRCC), but data from randomized trials on the sequential use of temsirolimus are lacking. We retrospectively studied the efficacy and safety of temsirolimus therapy following failure of rTKI therapy. Twenty-nine patients treated with temsirolimus (25 mg/week) following progression on rTKI therapy were studied at four institutions. All patients had failed at least one prior rTKI therapy (sunitinib, n = 6; sorafenib, n = 1; both, n = 22). Over 80% had two or more prior therapies. Data on efficacy (response assessment, progression-free survival [PFS], overall survival [OS]) and safety (NCI-CTC) were analyzed. Adverse events occurred in 90% of patients with the majority being grade 1 (n = 4, 14%) or grade 2 (n = 12, 41%). Most grade 3/4 toxicities (n = 10, 34%) were manageable and included anemia (n = 4, 14%), leukopenia/neutropenia (n = 2, 7%), hyperglycemia (n = 1, 3%), acidosis/alkalosis (n = 2, 7%), and infection (n = 1, 3%). One patient discontinued temsirolimus for grade 3 pneumonitis. Median (range) PFS and OS were 5.1 months (1-10.4) and 18.0 months (12.6-23.3), respectively. Best response included partial response (n = 1) and stable disease (n = 15) for a disease control rate of 55%, and disease progression of 45% (n = 13). Temsirolimus after rTKI failure appears to provide promising safety and efficacy comparable to other treatment options in pretreated patients with mRCC.

Subsequent chemotherapy reverses acquired tyrosine kinase inhibitor resistance and restores response to tyrosine kinase inhibitor in advanced non-small-cell lung cancer

BackgroundPatients with advanced or metastatic non-small cell lung cancer (NSCLC) can develop acquired resistance to epidermal growth factor receptor tyrosine kinase inhibitors (TKIs) erlotinib and gefitinib. Here, we report the successful treatment with alternating chemotherapy and TKIs of two cases of advanced NSCLC who developed resistance to TKI.Case presentationTwo patients with advanced or metastatic NSCLC were treated with palliative chemotherapy followed by erlotinib/gefitinib. When TKI therapy failed, two cycles of chemotherapy were provided, which were followed by re-challenge with erlotinib or gefitinib.ConclusionNSCLC patients with acquired TKI resistance should be managed aggressively whenever possible. Subsequent chemotherapy and target treatment is one of the reasonable choices for those with an initial dramatic clinical response with erlotinib/gefitinib treatment. Further studies are warranted to substantiate the association of erlotinib /gefitinib treatment with the efficacy of NSCLC patients with acquired TKI failure.

Use of direct sequencing for detection of mutations in the BCR-ABL kinase domain in Slovak patients with chronic myeloid leukemia

The presence of BCR-ABL oncogene mutations in patients with chronic myeloid leukemia (CML) may be responsible for the failure of tyrosine kinase inhibitor (TKI) treatment. The aim of the study was to evaluate the frequency of BCR-ABL gene mutations in patients with CML treated with tyrosine kinase inhibitors. Our lab received 64 samples (34 women, 30 men) from patients with CML who failed or had suboptimal response to TKI treatment. The mutation analysis was performed in 61 patients with CML, 3 patients could not be tested because of inadequate RNA quality. An 866 base pair fragment containing the ABL kinase domain was amplified in a seminested RT (reverse transcriptase)-PCR and then sequenced using Applied Biosystems BigDye Terminator chemistry with two pairs of primers. We analyzed 61 patients with CML, 11 mutations were detected in 13 (21%) patients and SNP (single nucleotide polymorphism) in 6 patients (10%). In addition to 9 point mutations (G250E / F317L, F359V, L387M, Y253H, M388L, M244V, T315I, D276G), 35 bp insertion between exons 8 and 9 and deletion exon 7 were detected. Our results demonstrate that direct sequencing is suitable for routine clinical monitoring patients with CML and may be useful for optimizing therapy.

Successful Rechallenge with Gefitinib for an Initial Erlotinib-Responder with Advanced Lung Adenocarcinoma

Although failure of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKI) is generally believed to be associated with cross-resistance to other EGFR TKI, the benefit of administering erlotinib as a second EGFR TKI after resistance of gefitinib as the first TKI has been well known. However, good response to gefitinib after an initial response to erlotinib has been rare. We report that a 45-year-old woman (never smoked), with lung adenocarcinoma and EGFR mutation, showed an initial response to erlotinib, and then responded to gefitinib again.

Impact of Prior Second-Generation Tyrosine Kinase Inhibitors on the Outcome of Hematopoietic Stem Cell Transplantation for Chronic Myeloid Leukemia

AbstractAbstract 2267Prior to the introduction of the tyrosine kinase inhibitors (TKI) into clinical practice, the only curative therapy for chronic myeloid leukaemia (CML) was allogeneic hematopoietic stem cell transplantation (HSCT). HSCT is nowadays recommended for patients in accelerated phase, blastic phase or with the T315I mutation and for patients who experience second-line TKIs (TKI2) failure or intolerance. The impact of TKI2 for CML on the results of subsequent HSCT has not yet been clearly established, although preliminary data does not suggest an increase of non relapse mortality (NRM) in patients previously treated with these agents. To assess whether exposure to TKI2s before HSCT adversely affects outcome, we retrospectively analyzed 31 patients with CML reported to the French registry for HSCT between January 2001 and December 2008 who received a first HSCT for imatinib resistant or intolerant CML subsequently treated with either nilotinib or dasatinib or both.The median age at diagnosis was 39.8 years (range, 19–61). At the start of TKI, 15 (48%) patients were in chronic phase, 12 (39%) patients were in accelerated phase and 4 (13%) patients were in blast crisis. For chronic phase patients, 6 (40%) patients were classified as low Sokal risk, 7 (46%) as intermediate risk, and 2 (14%) as high risk. After imatinib failure (among the 27 patients in chronic or accelerated phase at diagnosis), 21 and 6 patients received dasatinib and nilotinib, respectively. Among these patients, 9 patients received a third line therapy, including 5 sequential therapies with both drugs. The best response to the second and third-line treatments with TKI2 was a complete molecular response in 2 patients, a major molecular response in 2 patients, a complete cytogenetic response (CCR) in 7 patients, a complete hematologic response in 14 patients and no response in 2 patients. 14 patients eventually failed TKI2 treatment because of resistance, whereas 8 were considered as intolerant. Of 14 patients who developed resistance to TKI2, 2 had a mutation identified (T315I in both cases).Median interval from diagnosis to HSCT was 19 months (range, 3–151). At time of transplant, 21 patients were in chronic phase, 10 in accelerated phase and none in blast crisis. 19 patients received a graft from an unrelated donor whereas 12 a match related donor. Stem cell source was peripheral blood, bone marrow or cord blood in 20, 8 and 3 patients, respectively. The conditioning regimen was myeloablative in 21 patients combining either TBI and cyclophosphamide (9 patients) or high dose IV busulfan and cyclophosphamide (12 patients), and a RIC for 10 patients. All patients engrafted successfully: median time to neutrophil and platelet recovery was 18 days and 21 days respectively. Grade 2–4 acute graft-versus-host disease (aGVHD) was observed in 11 (37.9%) patients; grade 3–4 aGVHD occurred in 6 (20.6%) patients. Chronic GVHD was observed in 15 (60%) of 25 patients alive after day 100. The median follow-up after HSCT is 27 months (range, 1.2–50.2). At time of analysis, 11 (35%) patients died, 7 (22.5%) from NRM and 4 (12.5%) from progression of disease. NRM was due to infection (3 patients), GVHD (2 patients), post transplant lymphoma disease (1 patient) and unknown cause (1 patient). The 1-year overall survival (OS) was 79.2% (95% CI, 64,3-94,1%) and the estimated 2-year OS was 55,5% (95% CI, 35,0-75,9%). One-year relapse and NRM rates were respectively 10,3% (95% CI, 2.5–24.6%) and 19.1% (95% CI, 6.7–36.2%). In univariate analysis, no variable had a significant impact on outcome among Sokal score, disease phase at diagnosis, Grathwol score, age at HSCT, time from diagnosis to HSCT, or quality of response before HSCT. In a multivariate analysis, only quality of response (at least better than CCR) was significantly associated with a better outcome in terms of OS (p=0.0459, HR=0.17, 95% CI=0.03-0.97).In conclusion, TKI2 prior to HSCT did not result in an increased risk of NRM. However, our observation that patients in cytogenetic or molecular response at time of HSCT have a significant better outcome underscores the importance of a stringent prospective molecular monitoring under TKI2 therapy and the need for prognostic factors of response under TKI2. Such elements could help to better define after initiating TKI2 treatment patients that could really benefit from HSCT and the best timing of the procedure. Disclosures:No relevant conflicts of interest to declare.

Outcome of Patients (pts) with Chronic Myeloid Leukemia (CML) After Failure to 2nd and 3rd Tyrosine Kinase Inhibitors (TKIs)

AbstractAbstract 1238 Background:First and second generation tyrosine kinase inhibitors are effective for most pts with CML in chronic phase. Approximately 80% of pts achieve complete cytogenetic response (CCyR) with imatinib, but nearly 15% of them eventually lose response. With dasatinib, nilotinib or bosutinib, approximately 50% of those who failed imatinib achieve CCyR, and about 15% of them eventually lose response. Using one of these agents after failure to 2 prior TKIs results in CCyR in only about 20%, usually of short duration. Thus, some pts receive and fail therapy with 3rd TKI. No standard therapy is available for these pts. Although their outcome is presumed to be poor, this has not been systematically analyzed. Understanding their outcome is important since new investigational options are being developed to treat this patient population, and understanding their expected outcome is needed to better comprehend the results obtained. Aim:To analyze the outcome of patients who have received and failed 2nd and 3rd TKI. Methods:We reviewed the records of 64 CML pts treated at MD Anderson Cancer Center from 2005–2009 who received treatment with 3 sequential TKIs. The second TKI was bafetinib (INNO-406, 1pt), bosutinib (12 pts), dasatinib (13 pts), and nilotinib (38 pts). Upon failure to 2nd TKI, 27 pts were in chronic (CP), 20 pts in accelerated (AP), 14 pts in blast phase (BP), and 3 pts in 2nd chronic phase, and were started on a 3rd TKI: bafetinib (6 pts), bosutinib (12 pts), dasatinib (35 pts), and nilotinib (11 pts). Results:After a median follow-up of 36 months (mo) (range, 3 – 71), 14 (22%) pts were still on 3rd TKI, including nilotinib (4 pts), dasatinib (7 pts), bafetinib (1 pt), and bosutinib (2 pts). Fifty (78%) pts failed therapy, including 16 pts (1 in 2nd CP, 2 in CP, 4 in AP, and 9 in BP) died during therapy with 3rd TKI. Among the 34 pts alive after 3rd TKI failure, their median age was 59 years (range, 19 to 92), and 17 were female. Their median time from diagnosis of CML was 76 mo (22 to 241). They failed the 3rd TKI after a median of 5.8 mo (range, 0.3 to 45) on therapy, with 27 pts being resistant (1 had minor cytogenetic response, all others 100% Ph+) and 7 pts were intolerant to 3rd TKI. The best response to a 3rd TKI was 1 partial cytogenetic (PCyR), 1 minor and 1 minimal cytogenetic response, 7 complete hematologic responses (CHR), and 24 with no response (NR). Upon failure to 3rd TKI, 16 pts were in CP (4 with BCR-ABL kinase domain mutations including two F359V, and one Y253H and one F317L), 11 in AP (6 with BCR-ABL kinase domain mutations including two G250E, and one each for F317L, F359C, T315I, and F317L), and 7 in BP (3 pts with BCR-ABL kinase domain mutations, two T315I and one V299L). These stages at the end of 3rd TKI represented no stage change in 26 patients, a progression in 5 pts (3 from CP to AP, 1 from CP to BP, 1 from AP to BP), and an improvement in 3 (from AP to CP in 2, from BP to AP in 1). Of those in CP, 16 pts were in complete hematologic responses (CHR). The median Ph+ metaphase after failure to 3rd TKI was 94% (8 to 100). After failure to 3rd TKI, 4 pts received dasatinib, 5 nilotinib, 4 bafetinib, 2 AP24534, 3 omacetaxine + imatinib, 6 single-agent omacetaxine, 4 stem cell transplantation, and 1 each for MK-0457, hydroxyurea, vincristine + deaxmethasone, idarubicin + imatinib + Ara-C, and DCC-2036. One pt was lost to follow-up. Response to subsequent therapy is described in the table 1 . After a median follow-up of 4 mo since failure to 3rd TKI, 15 of 34 pts have died, including 4 of 16 in CP, 5 of 11 in AP, and 6 of 7 in BP. The median survival from failure to 3rd TKI was 25 mo (12 mo for pts in CP, 6 in AP, and 1 in BP). Among patients who are still alive, 12 pts are still receiving the 4th therapy which were 3 pts received nilotinib, 2 dasatinib, 2 homoharringtonine, 2 AP245341, 1 bafetinib, 1 DCC-2036, and 1 hydroxyurea since failure to 3rd TKI, and 6 pts have changed to subsequent therapies after 4th therapy, including 5 pts on AP24534, 1 pt on XL228, and one lost to follow-up. Conclusions:Patients who have failed therapy with 2nd and 3rd TKI have a very poor prognosis with rare responses and a very short expected survival. New therapies that may improve their outcome and prolong their survival are urgently needed for this patient population.Table 1Response to treatment after 3rd TKI failureHematologicCPAPBPOverallHematologic responseCHR437Cytogenetic responsePCyR11Minor CyR11Minimal CyR11No response107724Total1611734 Disclosures:No relevant conflicts of interest to declare.

Aktueller Stellenwert von Erlotinib und Gefitinib in der palliativen Therapie des NSCLC – welche Bedeutung hat der EGF-R-Mutationsstatus?

In spite of intensive research and a huge amount of chemotherapy trials, the prognosis of metastastic non-small cell lung cancer (NSCLC) is still poor. Erlotinib and Gefitinb are tyrosine kinase inhibitors (TKIs) which act against the EGF receptor (EGF-R). Activation of mutations in the tyrosine kinase domain leads to an increase in effectiveness. What is the clinical impact of EGF-R mutation screening? What value do TKIs in 1st, 2nd and 3rd line have in therapy for metastatic NSCLC? Which treatment options exist after failure of TKI in the 1st line? These and other clinically relevant questions in the context of TKIs are discussed in the present comprehensive review.

Antitumor activity of sequential treatment with tyrosine kinase inhibitors (TKI) after failure of RAD001 in metastatic renal cell carcinoma (mRCC).

e15132 Background: There are only limited data for the outcome of mRCC patients after failure of both TKI and RAD001 treatment. We retrospectively analysed patients who received subsequent treatment after failure of RAD001. Methods: 39 patients who failed at least one TKI and RAD001 were identified and retrospectively studied at our institution. 15 patients received additional therapy, of whom 14 were evaluable for response. Subsequent treatment consisted of: sunitinib (N=5), sorafenib (N=7), both TKI sequentially (N=2), bevacizumab/IFN (N=1), and an investigational agent (N=1). At start of post-RAD001 therapy 6 patients (40%) had high risk, 7 patients (47%) had intermediate and 2 patients (13%) low risk according to MSKCC. Overall survival (OS) was calculated from the initiation of first TKI therapy. Results: Median progression-free survival (PFS) of first-line TKI was 10.7 and 5.8 months in patients with and without post-RAD001 treatment, respectively. However, PFS of RAD001 was similar in both groups (4.7 and 5 months). Subsequent systemic treatment after RAD001 was associated with a PFS of 5.1 months. Best response consisted of 64% SD (N=9), 21% PR (N=3), and 14% PD (N=2). Six patients (40%) were re-exposed to a previously given TKI, and 9 patients (60%) received a different systemic treatment. Eight patients are still on treatment, while 2 patients switched to best supportive care. The median OS for patients with and without post-RAD001 treatment is 28.2 and 21.2 months (P=0.08), respectively. Conclusions: Subsequent treatment after failure of TKI and RAD001 is associated with a promising PFS of 5.1 months and disease control in the majority of patients (86%). However, subsequent therapy was given to patients who achieved superior PFS response to initial TKI exposure, which may indicate an important factor for patient selection for subsequent therapy after failure of TKI and RAD001 in the clinic. Author Disclosure Employment or Leadership Position Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Novartis, Pfizer, Roche Bayer, Novartis, Pfizer, Roche Wyeth Novartis, Pfizer

Mechanisms of Resistance to Imatinib and Second-Generation Tyrosine Inhibitors in Chronic Myeloid Leukemia

Targeted therapy in the form of selective tyrosine kinase inhibitors (TKI) has transformed the approach to management of chronic myeloid leukemia (CML) and dramatically improved patient outcome to the extent that imatinib is currently accepted as the first-line agent for nearly all patients presenting with CML, regardless of the phase of the disease. Impressive clinical responses are obtained in the majority of patients in chronic phase; however, not all patients experience an optimal response to imatinib, and furthermore, the clinical response in a number of patients will not be sustained. The process by which the leukemic cells prove resistant to TKIs and the restoration of BCR-ABL1 signal transduction from previous inhibition has initiated the pursuit for the causal mechanisms of resistance and strategies by which to surmount resistance to therapeutic intervention. ABL kinase domain mutations have been extensively implicated in the pathogenesis of TKI resistance, however, it is increasingly evident that the presence of mutations does not explain all cases of resistance and does not account for the failure of TKIs to eliminate minimal residual disease in patients who respond optimally. The focus of exploring TKI resistance has expanded to include the mechanism by which the drug is delivered to its target and the impact of drug influx and efflux proteins on TKI bioavailability. The limitations of imatinib have inspired the development of second generation TKIs in order to overcome the effect of resistance to this primary therapy. (Clin Cancer Res 2009;15(24):7519-27).

Frequency of BCR‑ABL gene mutations in Polish patients with chronic myeloid leukemia treated with imatinib. A final report of the MAPTEST study

The presence of BCR-ABL oncogene mutations in patients with chronic myeloid leukemia (CML) may be responsible for the failure of tyrosine kinase inhibitor treatment. The aim of the study was to evaluate the frequency of BCR-ABL gene mutations in patients with CML (the MAPTEST study) treated with imatinib (IM). Direct sequencing analysis of BCR-ABL gene was performed in 92 patients treated with IM for more than 3 months. The mean time of IM treatment was 18 months. At the time of the analysis, 75 patients were in the first chronic phase (CP), 4 in the second CP, 5 in the acceleration and 8 in the blastic phase. Fifty-seven patients (62%) were treated with IM at a daily dose of 400 mg and 35 patients with higher doses (600 or 800 mg daily). Inclusion criteria were based on the European Leukemia Net definitions for failure and suboptimal response to IM. Twelve mutations were detected in 11 of 92 patients, including 4 mutations (36.7%) diagnosed during CP, 3 (27.3%) in acceleration, and 4 (36.7%) in blast crisis. In 1 patient with lymphoid blast crisis of CML coexisting F359V and Y253F mutations were detected. In the whole group mutations were detected in 2 of 5 patients (40%) with primary resistance (M351T, F359V + Y253F) and in 9 of 87 patients (10.3%) (E255K, T315I-3x, M351T, E355G, F359V-2x) with acquired resistance to IM. The study confirmed the usefulness of BCR-ABL gene mutation screening in patients with CML resistant to IM therapy.