Clinical Resistance To Ruxolitinib Is More Frequent In Patients Without MPN-Associated Mutations and Is Rarely Due To Mutations In The JAK2 Kinase Drug-Binding Domain

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1591-1591 ◽  
Author(s):  
Annalisa Andreoli ◽  
Emmanuelle Verger ◽  
Marie Robin ◽  
Emmanuel Raffoux ◽  
Jean-Marc Zini ◽  
...  
Keyword(s):  
Clinical Practice ◽  
Board Of Directors ◽  
Research Funding ◽  
Kinase Domain ◽  
Drug Binding ◽  
Spleen Size ◽  
Advisory Committees ◽  
Primary Resistance ◽  
Secondary Resistance ◽  
Clinical Resistance

Abstract Background Ruxolitinib (RUX) has been recently approved for the therapy of patients (pts) with myelofibrosis (MF). Although various definitions for response and resistance to this drug have been proposed in the setting of clinical trials, none of them has been validated in clinical practice. Based on RUX efficacy, it is assumed that primary resistance is related to absence or minor reduction in spleen size and constitutional symptoms, while spleen regrowth and recurrence of symptoms after a period with good response establish secondary resistance. The extents of all these parameters have not been clearly defined yet for patients’ management in clinical practice. On the other hand, several biological mechanisms of resistance have been described. In particular, acquisition of new mutations in the predicted RUX-binding region (like Y931C, G935R, R938L, I960V and E985K) was previously shown to confer resistance to JAK inhibitors in vitro (Hornakova et al, Haematologica, 2011; Weigert et al, J Exp Med, 2012). Such mutations have not yet been found in pts treated with RUX. Aims 1) Characterize the parameters leading physicians to conclude that RUX-resistance (RUX-R) was reached in a cohort of consecutive MF pts treated with RUX in clinical practice. 2) Identify a molecular signature of RUX-R. Methods Consecutive pts with MF treated with RUX in our center were identified. Clinical characteristics and evolution during and after RUX therapy were collected. Pts were screened for JAK2V617F (PCR), MPL, TET2, and SRSF2 mutations (direct Sanger sequencing). In addition, the last exons of JAK2 corresponding to the RUX-binding domain were sequenced in RUX-R pts. Results In all, 41 pts received RUX between Nov 2009 and May 2013, including 21 primary, 8 post-PV and 12 post-ET MF, and full data were available in 39 of them for this analysis. Median age was 64 yrs; IPSS risk score was high in 46%, and int-1 or 2 in 54%; 72% were JAK2V617F positive, 10% MPL515-positive. Overall, 16/39 (41%) pts were considered RUX-R by their physician, only 4/16 being primary resistant with <10% reduction in spleen size after a median RUX exposure of 89 days. Median spleen size reduction (best response by palpation, compared with baseline) was 60% in the whole cohort, 50% in pts who developed secondary resistance, and 80% in non RUX-R pts. Secondary resistance was always due to regrowth of spleen either alone (n=6), or associated with recurrence of symptoms (n=5), or with marked leukocytosis (n=1). 44% of RUX-R pts also had hematological intolerance (35% in non RUX-R pts). Median RUX exposure was 298 days (Q1-Q3: 159-640), longer in RUX-R pts compared to non RUX-R pts (median of 383 vs. 292 days). Median starting dose was similar in both groups (15 mg BID), but a higher proportion of pts in the RUX-R group had to reduce the dose < 10 mg BID during follow-up (29% vs 17% in non RUX-R pts). However, 43% of RUX-R was noticed in pts on stable doses, and in 36% after dose escalation (up to 25 mg BID). Among RUX-R pts, there was a higher proportion of pts with high IPSS (56% vs. 39% in non RUX-R; p=0.06), and of post-ET MF (38% vs. 26%; p=0.08). Molecular profile of pts developing RUX-R showed that 31% of them had no mutation detectable at diagnosis in JAK2, MPL, TET2, and SRSF2, compared to 9% of pts in the non RUX-R group (p=0.003). Sequencing of the JAK2 kinase domain in samples taken at the time of resistance in 14/16 RUX-R pts did not detect any new mutation potentially affecting drug binding. Conclusion In this series of consecutive pts treated with RUX in a single center, RUX-R was observed in 41% of pts, mostly as a late event (after median exposure of 1 year) and rarely as primary resistance (10%). RUX-R was always associated with spleen regrowth, and accompanied with recurrence of symptoms in half of the cases. RUX-R was more frequently seen in pts with high risk IPSS score, post-ET MF, smaller spleen response (-50% vs. -80% in non RUX-R), but the only factor significantly associated with RUX-R was the absence of mutation in all of the following genes: JAK2, MPL, TET2, and SRSF2. Furthermore, sequencing of the kinase domain of JAK2 in RUX-R pts didn’t detect any mutation possibly affecting drug binding, suggesting that such mechanism is rarely involved in clinical resistance to RUX. Other mechanisms, like the phenomenon of “persistence” to JAK inhibitor therapy described by Koppikar at al (Nature, 2012) should be investigated in these pts. Disclosures: Robin: Novartis: Research Funding. Rea:Novartis: Honoraria; BMS: Honoraria; Pfizer: Honoraria; Teva: Honoraria; Ariad: Honoraria. Giraudier:NOvartis: Consultancy, Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; BMS: Consultancy, Honoraria. Kiladjian:AOP Orphan: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Sanofi: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Celgene: Research Funding; Novartis: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding.

scholarly journals Recurrent Mutations in CCND3 Confer Clinical Resistance to FLT3 Inhibitors

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 677-677 ◽  
Author(s):  
Catherine C. Smith ◽  
Aaron D. Viny ◽  
Evan S. Massi ◽  
Cyriac Kandoth ◽  
Nicholas D. Socci ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Research Funding ◽  
Acquired Resistance ◽  
Cyclin D3 ◽  
Phase Ii Trials ◽  
Advisory Committees ◽  
Primary Resistance ◽  
Clinical Resistance ◽  
Recurrent Mutations ◽  
Flt3 Inhibitors

Abstract Background. Activating mutations in FLT3 occur in ~30% of adult acute myeloid leukemia (AML) cases, including internal tandem duplication (ITD) mutations (~25%) and point mutations in the tyrosine kinase domain (KD). In recent years, multiple selective and potent FLT3 inhibitors such as quizartinib, PLX3397, crenolanib and ASP2215 have demonstrated encouraging preliminary clinical activity in FLT3 mutant AML. Both quizartinib (Schiller et al, ASCO 2014) and ASP2215 (Levis et al, ASCO 2015) have reported composite complete remission rates (CRc) as high as ~50% in phase II trials. Despite these high response rates, the majority of patients relapse after initial response (acquired resistance) and a significant proportion of patients also fail to respond at all (primary resistance). On-target resistance due to secondary KD mutations in FLT3 is a common cause of acquired resistance to the clinically active FLT3 inhibitors quizartinib (Smith et al. Nature 2012) and PLX3397 (Smith et al, Cancer Discovery 2015). However, the causes of primary clinical resistance to FLT3 inhibitors have not been characterized. We performed targeted capture based sequencing of sorted pre-treatment blasts from 8 responding (R) and 21 non-responding (NR) patients treated on the phase I/II trial of PLX3397 in FLT3-ITD+ AML. We deeply sequenced the coding regions of 585 genes known to be mutated in hematologic malignancies/solid tumors and identified genes mutated only in NR patients (compared to genes mutated in both R and NR patients). Results. The number of mutations detected in genes other than FLT3 ranged from 2-18 per sample. There was no increase in the number of mutations found in patients with pre-existing hematologic conditions or in NR patients. Surprisingly, one of the most frequently mutated genes observed exclusively in NR patients was CCND3, the gene encoding cyclin D3, which has rarely been reported to be mutated in AML, though it is mutated in 38% of sporadic Burkitt's lymphoma (BL). A total of 4 individual mutations in CCND3 (Q276*, Q280fs, R271fs, and T283A) were identified in 3/21 NR patients (one patient had both Q276* and Q280fs). No CCND3 mutations were found in R patients. The identified mutations were the same mutations commonly found in BL, known to result in a more stable isoform of cyclin D3 and retain sensitivity to CDK4/6 inhibitors (Schmitz et al., Nature 2012). Expression of the Q276* and T283A mutations in FLT3-ITD+ MV4;11 cells conferred resistance to apoptosis induced by several FLT3 inhibitors (PLX3397, AC220 and crenolanib). However, inhibition of CDK4/6 activity in CCND3 mutant MV4;11 cells by either the CDK4/6 inhibitor palbociclib or the combined FLT3-CDK4/6 inhibitor AMG925 (FLX925) was unable to restore sensitivity to FLT3 inhibition. Moreover, CCND3 mutant MV4;11 cells demonstrated no increase in Rb phosphorylation, suggesting resistance to FLT3 inhibitors facilitated by CCND3 mutations is not predicated on CDK4/6 activation of Rb-dependent E2F-mediated transcription. Conclusions. We have identified recurrent mutations in CCND3, a gene not previously known to be commonly mutated in AML, as a novel cause of clinical primary resistance to FLT3 inhibitors in AML. This represents the first report of a specific non-FLT3 dependent mechanism of clinical resistance to FLT3 inhibitors. Unlike in BL, the functional effects of CCND3 mutations in FLT3-ITD+ AML do not appear to be mediated via CDK4/6 activity and is therefore unresponsive to CDK4/6 inhibition. The molecular mechanism(s) of CCND3-mediated resistance to FLT3 inhibitors are currently being investigated. Disclosures Smith: Plexxikon: Research Funding; Astellas: Research Funding. Off Label Use: Investigational use of PLX3397 in AML. Hsu:Plexxikon Inc.: Employment. West:Plexxikon Inc.: Employment. Bollag:Plexxikon Inc.: Employment. Levine:Foundation Medicine: Consultancy; CTI BioPharma: Membership on an entity's Board of Directors or advisory committees; Loxo Oncology: Membership on an entity's Board of Directors or advisory committees. Shah:Bristol-Myers Squibb: Research Funding; Pfizer: Research Funding; Plexxikon Inc.: Research Funding.

scholarly journals ASXL1 Mutations Detectable at Diagnosis May Predict Response to Imatinib in Patients with Chronic Myeloid Leukemia

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 4148-4148
Author(s):  
Marcin M Machnicki ◽  
Monika Pepek ◽  
Iwona Solarska ◽  
Joanna Niesiobedzka-Krezel ◽  
Ilona Seferynska ◽  
...  
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Board Of Directors ◽  
Myeloid Leukemia ◽  
Mutation Frequency ◽  
Kinase Domain ◽  
Advisory Committees ◽  
Secondary Resistance ◽  
Genetic Aberrations ◽  
Paired Samples ◽  
Clinical Resistance

Clinical resistance to tyrosine kinase inhibitors (TKI) remains a significant problem in the therapy of patients with chronic myeloid leukemia (CML). Although BCR-ABL1-kinase domain mutations are the major cause of resistance to TKI, some patients manifest primary or develop secondary resistance to TKI without detectable BCR-ABL1 mutations. We aimed to assess the prevalence of additional gene mutations in a group of 50 patients with primary (n = 26) or secondary resistance (n = 24) to TKI, in most cases to imatinib (n = 49) and in one to dasatinib. We employed ~1000 genes custom target enrichment kit and next-generation sequencing on Illumina platform, as well as Sanger sequencing. In 21 patients, we were able to match and analyze paired samples collected at diagnosis (before treatment) and at the time of resistance and in five other cases we analyzed additional samples collected later during TKI-resistant chronic phase or in blast crisis. The most frequent genetic aberrations detected at the time of TKI-resistance were mutations in ASXL1 and BCR-ABL1 kinase domain coding sequence, present in 28% (14/50) and 26% (13/50) of patients, respectively. Both genes were mutated in 12% of patients (6/50), while 30% (15/50) had either ASXL1 or BCR-ABL1 mutations alone. Non-recurrent genetic aberrations in other genes were also noted in single patients (e.g. DNMT3A mutations). According to COSMIC database, all but three ASXL1 mutations detected in this study were previously described in hematologic malignancies and all (including the novel ones) are predicted to introduce stop codons or cause frameshifts in codon range of 512-943, thus truncating the protein before the C-terminal PHD domain. Among patients with available paired samples three had more than one ASXL1 mutation at various time points and in all of them we observed dynamics of specific ASXL1 mutations, related partially to the leukemic cell content in the sample but also providing evidence of clonal evolution (Table 1). In most of patients with concurrent ASXL1 and BCR-ABL1 mutations, we observed that both mutations were present with similar variant allele frequency (VAF), suggesting that ASXL1 mutations occur in Philadelphia-positive leukemic clones (Table 2). ASXL1 mutation frequency was significantly higher in TKI-resistant patients, than in our previously characterized group of CML patients without resistance, who achieved major molecular response (28% ; 14/50 vs 5.6% ; 2/36, respectively, p = 0.0105, Fisher exact test). All ASXL1-mutated patients with secondary (n = 1) or primary resistance (n = 5) for whom diagnostic sample was available, carried ASXL1 mutation also at the time of diagnosis. No significant difference in mutation frequency was found between patients with primary and secondary resistance (ASXL1 mutation, 26.9% vs 29.2% ; BCR-ABL1 mutation, 15.4% vs 37.5%). Our results provide evidence that preexisting ASXL1 mutations in BCR-ABL1-positive leukemic clone present at diagnosis may have impact on clinical response to imatinib and may be useful in assessing the risk of treatment failure. Disclosures Niesiobedzka-Krezel: Novartis: Honoraria. Seferynska:Novartis: Honoraria. Gora Tybor:Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Sacha:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

Pomalidomide with Low Dose Dexamethasone Is Effective Irrespective of Primary or Secondary Resistance to Lenalidomide but the IMiD-Free Interval Is Important

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3310-3310 ◽  
Author(s):  
Meletios A Dimopoulos ◽  
Maria Roussou ◽  
Nikolaos Kanellias ◽  
Maria Gavriatopoulou ◽  
Magdalini Migkou ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Research Funding ◽  
Low Dose ◽  
Phase Iii ◽  
Advisory Committees ◽  
Primary Resistance ◽  
Secondary Resistance ◽  
Development Of Resistance ◽  
Free Interval

Abstract Pomalidomide with low dose dexamethasone (Pd) is a standard treatment for patients who have failed both lenalidomide (Len) & bortezomib (Bor). Phase III studies showed that Pd is active irrespective of the number of prior therapies and whether Len or Bor were the last therapies prior to Pd. However, it remains unclear what is the activity of Pd when administered immediately after refractoriness to Len or when is administered following secondary resistance. Furthermore, the importance of the time elapsed from the administration of Len to Pd has not been explored. We analyzed the outcomes of 116 consecutive patients with MM after failure of both Len & Bor that were treated in the Department of Clinical Therapeutics, National and Kapodistrian University of Athens, and who all received pomalidomide 4 mg with weekly dexamethasone. Median age was 62 years (range 38-86 years); median number of prior treatments was 4 (range 1-9), 58% had received ASCT, 73% were refractory to the last Bor-based regimen and 90% were refractory to the last Len-based regimen. All patients had MM refractory to the last regimen, but 40% had ≥PR to their most recent regimen prior to development of refractoriness. The last regimen prior to Pd included Bor in 62 (53%), Len in 35 (30%) and conventional chemo in 19 (17%). On intent to treat, 34 (29%) patients achieved ≥PR (CR: 3%, VGPR: 7%, PR: 19%). In those which received Len just prior to Pd, ≥PR rate was 26% vs 33% for Bor and 21% for other regimens (p=0.55). Among patients with <PR to any prior Len therapy (primary resistance to Len, N=45) ≥PR was 24% vs 31% for those who had ≥PR to any prior Len during the course of their disease (secondary resistance to Len, N=71) (p=0.42). Among patients who received Len just prior to Pd and who achieved ≥PR before development of resistance, 29% achieved ≥PR vs 18% for those with <PR (p=0.49). Thus, Pd was effective irrespective of primary or secondary refractoriness to Len. Median follow up was 29 months and 95 (83%) patients have progressed or died. Median PFS was 5.2 months (95% CI 3.8-6.5). Patients who received Len as their last treatment before Pd had PFS similar to that of patients who received either Bor or other regimens (p=0.8). Patients who had ≥PR when treated with Len immediately before Pd (secondary resistant to Len), had PFS similar to that of those with <PR (p=0.61). PFS of patients with primary vs secondary resistance to Len was 4.9 vs 6.5 months (p=0.18). After Pd, 59 (51%) patients received further therapy. PFS2 for all patients is 9.6 months (95% CI 7.6 -10.4). PFS2 was similar for patients who received Len vs Bor or other therapies immediately prior to Pd (9 vs 9.9 vs 7.4 months, p=0.55). For those who had Len just prior to Pd those who achieved ≥PR before development of Len resistance PFS2 was 9.7 vs 7.2 months for those who had <PR (p=0.36) and was similar for patients with primary vs secondary resistance to Len (8.7 vs 9.7 months, p=0.4). Median OS was 13 months (95% CI 9.7-16). OS of patients who received Len immediately before Pd was 11.3 vs 13 months for Bor (p=0.486). Among patients who received Len as their last regimen and who achieved ≥PR before development of resistance, there was a trend for longer OS (16.6 vs 9.9 months for those with <PR, p=0.3) and OS was 12.7 vs 15.7 months for patients with primary vs secondary resistance to Len (p=0.4). We then evaluated the role of time elapsed from the last exposure to Len until start of Pd. Median time from the last Len dose to Pd was 8 months; however, further analysis revealed that ≥PR was 68% for patients (N=29) who had ≥18 months since the last dose of Len. PFS of patients with an interval ≥18 months was 10.5 vs 4 months for those with <18 months (p=0.002) and OS was 20 vs 15 months for those with an interval 12-18 months vs 10 months for those with <12 months interval (p=0.01). These effects remained significant even after adjustment for the number of prior therapies and primary or secondary Len resistance. In conclusion, Pd is active in MM patients refractory to Len, independently of primary or secondary resistance to Len or if Len was used just prior to Pd. However, patients with ≥18 months of Len-free interval may have longer PFS and OS irrespectively of prior lines of therapy. These data indicate the potential role of "clonal tides" and the emergence of IMiD-sensitive clones after "IMiD-free" periods, but further investigation is needed to identify optimal treatment strategy. Disclosures Dimopoulos: Genesis: Consultancy, Honoraria; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Delimpasi:Genesis: Honoraria; Amgen: Honoraria; Janssen: Honoraria. Terpos:Genesis: Consultancy, Honoraria, Other: Travel expenses, Research Funding; Amgen: Consultancy, Honoraria, Other: Travel expenses, Research Funding; Takeda: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Other: Travel expenses, Research Funding; BMS: Consultancy, Honoraria; Novartis: Honoraria; Celgene: Honoraria. Kastritis:Janssen: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Genesis: Consultancy, Honoraria.

First-Line Treatment and Management of Chronic Myeloid Leukemia (CML) in Clinical Practice: Update of > 1800 Patients (Pts) in the WORLD CML Registry

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3750-3750
Author(s):  
Jorge E. Cortes ◽  
Ricardo Pasquini ◽  
Hagop M. Kantarjian ◽  
David Joske ◽  
Luis A Meillon ◽  
...  
Keyword(s):  
Clinical Practice ◽  
Board Of Directors ◽  
Research Funding ◽  
Disease Status ◽  
First Line ◽  
Employment Equity ◽  
Advisory Committees ◽  
Time Points ◽  
The World ◽  
Equity Ownership

Abstract Abstract 3750 Background: The WORLD CML Registry is a multinational, prospective registry established to longitudinally assess global patterns of current and evolving methods for diagnosis, treatment, and clinical outcome measures in pts with CML and to compare clinical practice patterns to management recommendations provided by the European LeukemiaNet (ELN; Baccarani M, et al. J Clin Oncol. 2009;27:6041–6051). Here, we report overall efficacy and safety data from this registry, as well as clinical monitoring practices and outcomes in the subgroup of pts with CML in chronic phase (CP) treated with first-line imatinib. Methods: Pts (≥ 16 y of age) with CML in CP, accelerated phase (AP), or blast crisis (BC) within 6 mo + 2 weeks of confirmed CML diagnosis were enrolled at sites in Latin America, Asia-Pacific, the United States, Russia, Turkey, the Middle East, and Africa. Baseline demographics and medical history were collected at enrollment; disease status and management information were collected at approximate 6-mo intervals or when there was a change in disease status/management. Adverse events (AEs) were collected only if they resulted in a dose/regimen change, nonadherence to treatment, or death. Results: A total of 1837 of the 1889 pts enrolled between February 2008 and December 31, 2010, were evaluable (ie, had confirmed informed consent forms and no protocol deviations) and are the basis for this analysis. Median age was 47 y (range, 16–92 y), and 58% of pts were male. CML diagnosis was established using hematologic (91% of pts), bone marrow (82%), cytogenetic (83%), and molecular (polymerase chain reaction [PCR]; 53%) assessments. Nearly all pts (94%) were initially diagnosed in CP (Table). As of the data cutoff (December 31, 2010), median overall survival (OS) and median event-free survival (EFS) in all pts were not reached. Estimated OS and EFS rates at 3 y were 90.4% and 74.8%, respectively. AEs reported in ≥ 1% of pts were thrombocytopenia (3%) and neutropenia (2%). In the CML-CP subgroup, imatinib (Glivec®/Gleevec®) was administered as first-line therapy (in clinical practice or in a clinical trial) to 63% of pts (n = 1083). Disease burden in CML-CP pts on imatinib over time was most commonly assessed via blood counts (Table). Cytogenetic and molecular assessments were used in a minority of CML-CP pts at most time points. Only 50% of pts had a disease assessment at 3 mo (hematologic, 49%; cytogenetic, 10%; molecular, 15%). Of the pts on first-line imatinib outside of a clinical trial setting (n = 1024), 95 (9%) had their dose increased, 77 (8%) had their dose decreased, and 82 (8%) were switched to nilotinib or dasatinib. In all CML-CP pts treated with first-line imatinib, estimated OS and EFS rates at 3 y were 92.1% and 76.6%, respectively (Table). Estimated OS and EFS rates at 3 y were higher in pts who had higher imatinib exposure (treatment received ≥ 85% of total days) vs pts who received imatinib treatment on < 85% of days. Conclusions: The majority of CML-CP pts treated with first-line imatinib did not have cytogenetic or molecular assessments in accordance with current ELN recommendations, particularly at early time points. Additionally, pts who had higher drug exposure to imatinib had higher estimated OS and EFS rates at 3 y than those who did not. Disclosures: Cortes: Novartis: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Ariad: Consultancy, Research Funding. Kantarjian:Novartis Pharmaceuticals Corp: Consultancy, Research Funding; BMS: Research Funding; Pfizer: Research Funding. Piccolo:Novartis Pharma AG: Employment. Zernovak:Novartis Pharmaceuticals Corp: Employment, Equity Ownership. Sivarathinasami:Novartis Healthcare Pvt. Ltd,: Employment. Eng:Novartis Pharmaceuticals Corp: Employment, Equity Ownership. Kim:Novartis: Consultancy, Research Funding, Speakers Bureau; BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; ARIAD: Research Funding; II-Yang: Consultancy, Honoraria, Research Funding. Hughes:Novartis Pharmaceuticals Corp: Consultancy, Honoraria, Research Funding; Bristol Myers Squibb: Consultancy, Honoraria, Research Funding; Ariad: Consultancy; CSL: Research Funding.

Outcome of Lower Risk Non Del 5q MDS after Failure of Erythropoiesis Stimulating Agents (ESA), and Impact of Post-ESA Treatment on Survival: A Retrospective European Study

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 1665-1665 ◽  
Author(s):  
Sophie Park ◽  
Jean-François Hamel ◽  
Andrea Toma ◽  
Charikleia Kelaidi ◽  
Maria Campelo Diez ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Lower Risk ◽  
Research Funding ◽  
Cooperative Groups ◽  
Second Line ◽  
Advisory Committees ◽  
Primary Resistance ◽  
Investigational Drugs ◽  
Significant Difference ◽  
Very High

Abstract Background : Most non-del 5q lower risk MDS patients (pts) are first treated with ESA, with about 50% (generally transient) responses, and second line treatments (TX) including hypomethylating agent (HMA), Lenalidomide (LEN) and investigational drugs are then often proposed, but their effect on overall survival (OS) is unknown. In a previous work on 253 such pts, we found worse OS with early failure to ESA, i.e. primary resistance (RES) or relapse (REL) < 6 months after ESA onset (Kelaidi, Leukemia, 2013), but only few pts had received, after ESA failure, TX other than RBC transfusions. In the present study, we gathered non-del 5q lower risk MDS treated with ESA from several EU MDS cooperative groups, and analyzed their outcome after ESA failure, and the effect of second line TX on survival. Methods : 1611 IPSS low and int-1 (lower risk) non del 5q MDS pts included in the French (GFM), Italian (FISM), Spanish (GESMD), Greek, Düsseldorf and Munich registries between 1997 and 2014, and treated by ESA were studied. Survival was assessed from failure of ESA (i.e. from primary failure evaluated after 12 to 24 weeks of ESA treatment, or from relapse after a response). Progression at ESA failure was defined upon progression to a higher IPSS-R class at ESA failure as compared with ESA onset. Results : At ESA onset, the 1611 pts were reclassified by IPSS-R in 16% very low, 54% low, 13% int, 6% high, 1% very high and 10% ND. HI-E (using IWG 2006 criteria) to ESA treatment was 66.9%, and the median duration of response was 15 months. The cohort of 1038 pts with ESA failure included 521 RES and 517 REL. Median OS was 4.2 years in REL and 3.7 years in RES pts (p=0.56), and no significant difference was seen, even after restricting the analysis to very low and low IPSS-R pts (p=0.81), or when analyzing "early" vs "late" failures, with cut-off points at 6 or 12 months, as we previously reported (Kelaidi, Leukemia, 2013). 336 (32%) pts received second line treatment (TX2) other than RBC transfusions, including HMA in 88 pts, LEN in 169 pts, and other TX (OT) in 79 pts (including 11 chemotherapy, 17 thalidomide, 11 immunosuppressors (ATG, cyclosporine), or investigational drugs), with response rates of 46%, 39% and 33% respectively (p=0.4). 87 pts had a third line TX (mostly a new drug, but also 7 pts who received HMA after LEN, and 33 pts LEN after HMA). Pts treated with LEN as TX2 were younger (median age 70 vs 75 for BSC, and 70 for HMA p<10-4), had more RARS (67% vs 28% for BSC and 27% for HMA, p<10-4), while pts treated with HMA as TX2 had more RAEB-1 (34% vs 10% for BSC and 12% for LEN, p<10-4) and more high and very high IPSS-R at onset of TX2 (48% vs 4.6% for BSC and 3.1% for LEN, p<10-4). Median OS for pts receiving BSC, LEN, HMA and OT as TX 2 was 4.3y, 3.7y (HR 1.1 [0.81-1.50] p=0.5), 2.1y (HR 1.59 [1.12-2.72], p=0.01) and 2.2y (HR1.17 [0.81-1.68], p=0.41) respectively (Figure). However, in a multivariate analysis adjusted on age, gender, and IPSS-R progression at ESA failure, OS difference became not significant. Analysis of AML progression in the different TX2 groups is currently being finalized. C onclusion: In this large multicenter retrospective cohort of non-del 5q lower risk MDS pts having failed ESA treatment, OS from failure was similar in RES and REL pts, contrary to our previous smaller experience. About 1/3 of the pts received second line treatments other than RBC transfusion, mainly LEN or HMA. However, none of those treatments was able to improve OS compared to BSC. Newer treatments are required in this situation, possibly including allogeneic SCT in younger pts. Figure 1. OS since ESA failure according to TX2 (Simon-Makuch method). Figure 1. OS since ESA failure according to TX2 (Simon-Makuch method). Disclosures Park: Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Hospira: Research Funding; Celgene: Research Funding. Off Label Use: Lenalidomide in non del 5q MDS. Santini:celgene, Janssen, Novartis, Onconova: Honoraria, Research Funding. Cony-Makhoul:BMS: Consultancy, Honoraria, Speakers Bureau; Novartis: Consultancy, Honoraria, Speakers Bureau. Cheze:Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees. Wattel:PIERRE FABRE MEDICAMENTS: Research Funding; CELGENE: Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Research Funding; NOVARTIS: Research Funding, Speakers Bureau; AMGEN: Consultancy, Research Funding. Vey:Celgene: Honoraria; Roche: Honoraria; Janssen: Honoraria. Fenaux:Amgen: Honoraria, Research Funding; Celgene Corporation: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Novartis: Honoraria, Research Funding.

scholarly journals Exploiting LY3009120 and Asciminib Combination to Target TKI-Resistant CML

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 3600-3600
Author(s):  
Milad Rouhimoghadam ◽  
Anthony D. Pomicter ◽  
Alexandria Van Scoyk ◽  
Greg Poffenberger ◽  
Ivaylo Kirov ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Board Of Directors ◽  
Binding Affinity ◽  
In Silico ◽  
Research Funding ◽  
Single Agent ◽  
Kinase Domain ◽  
Fluorescent Tracer ◽  
Advisory Committees ◽  
Study Management

Abstract The oncogenic BCR-ABL1 tyrosine kinase is the driver of chronic myeloid leukemia (CML) and Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ALL). Tyrosine kinase inhibitors (TKIs) targeting ABL kinase are generally effective, but subsets of patients treated with single-agent TKIs develop resistance due to mutations in BCR-ABL1 that impair TKI binding. We have previously reported that BCR-ABL1 compound mutants (exhibiting two mutations within the same BCR-ABL molecule) that include the T315I gatekeeper mutation confer a high degree of resistance to all clinical ABL TKIs used as single agents, including ponatinib and the allosteric inhibitor asciminib. However, combining asciminib with ponatinib provides an effective strategy for overcoming compound mutation-based resistance (Eide et al. Cancer Cell 2019). As the clinical utility of ponatinib is limited by cardiovascular toxicity, including arterial occlusive events (AOEs), we decided to search for alternative molecules for use in combination with asciminib. To identify functional ponatinib analogs, we performed Quantum Similarity Modeling (QSM) on the reported crystal structure of T315I mutant ABL1 kinase in complex with nilotinib and asciminib (5MO4) (Wylie et al. Nature 2017) to search for other molecules. Compared to conventional computational modeling, QSM identifies novel classes of structurally distinct compounds that are comparable on a quantum level by precisely defining their interaction with the target. Affinity inferred by close complementarity with the shared ligand-protein surface in the region of the surveyed binding site is mapped, using multiple weak local associations. Our in silico QSM platform combines quantum methods with machine learning to investigate extensive chemical spaces. We screened several million compounds against BCR-ABL1 and identified 51 potential candidates predicted effectively to block T315I mutant BCR-ABL1 when combined with asciminib. To prioritize potent and non-toxic drug combinations for further development against compound mutants, we initially profiled all 51 compounds for their efficacy against Ba/F3 BCR-ABL T315I cells, alone and in combination with asciminib (1 nM). Of 51 compounds, LY3009120, a pan-RAF inhibitor that is currently in phase I clinical development for advanced solid malignancies (Sullivan et al. Mol Cancer Ther 2020), showed strong activity against BCR-ABL T315I when combined with asciminib. These data provided proof of principle for the QSM approach. We next tested the efficacy of all 51 candidates ± asciminib against Ba/F3 cells harboring T315I-inclusive BCR-ABL1 compound mutants, including Y253H/T315I, E255V/T315I, H396R/T315I, G250E/T315I, and T315L as the most resistant mutants. Neither single agent showed any effect. However, LY3009120 strongly inhibited BCR-ABL1 compound mutants when combined with asciminib. No toxicity was observed against Ba/F3 parental cells, confirming that the effects of the combinations are mediated by inhibition of BCR-ABL1. Synergy quantification of the dose-response matrix for the LY3009120/asciminib combination using the Zero Interaction Potency model demonstrated highly synergistic interactions (Synergy score &gt; 10) between the two inhibitors. To directly assess the binding affinity of LY3009120 to the ABL1 kinase domain, we used the cell-based NanoBRET intracellular ABL1 kinase assay on HEK-293 cells expressing luciferase-tagged ABL1. The NanoBRET assay uses energy transfer to quantify the affinity of test compounds by competitive displacement of a cell-permeable fluorescent tracer that is reversibly bound to an ABL1-luciferase fusion protein. We found that LY3009120 competes off the fluorescent tracer at a low micromolar range (EC 50 = 0.75 μM), confirming direct binding of LY3009120 to the kinase domain of ABL1. We hypothesize that the binding of LY3009120 to the ABL1 kinase domain induces a conformational change that re-establishes asciminib binding to the myristoyl binding pocket, allowing for synergy. Studies to quantify the binding affinity of LY3009120 and asciminib to BCR-ABL1 mutants are underway, and data will be presented. In summary, our findings validate QSM as a novel in silico approach to identify TKI combinations. Combining LY3009120 with asciminib may be an effective, low-risk strategy to target BCR-ABL1 compound mutants in patients with clinical TKI resistance. Disclosures Deininger: SPARC, DisperSol, Leukemia & Lymphoma Society: Research Funding; Sangamo: Consultancy, Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy, Honoraria, Research Funding; Fusion Pharma, Medscape, DisperSol: Consultancy; Novartis: Consultancy, Research Funding; Blueprint Medicines Corporation: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Part of a Study Management Committee, Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Part of a Study Management Committee, Research Funding.

scholarly journals Ruxopeg, a Multi-Center Bayesian Phase 1/2 Adaptive Randomized Trial of the Combination of Ruxolitinib and Pegylated Interferon Alpha 2a in Patients with Myeloproliferative Neoplasm (MPN)-Associated Myelofibrosis

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 581-581 ◽  
Author(s):  
Jean-Jacques Kiladjian ◽  
Juliette Soret-Dulphy ◽  
Matthieu Resche-Rigon ◽  
Francoise Boyer-Perrard ◽  
Fiorenza Barraco ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Interferon Alpha ◽  
Research Funding ◽  
Phase 1 ◽  
Disease Assessment ◽  
Spleen Size ◽  
Phase 2 ◽  
Advisory Committees ◽  
Allele Burden ◽  
Dose Combination

Abstract Background MPN-associated myelofibrosis (MF) is a condition characterized by splenomegaly, anemia, bone marrow (BM) fibrosis and debilitating symptoms. About 80% of patients (pts) harbor a driver mutations in JAK2, CALR or MPL genes that can be used as biomarkers for minimal residual disease assessment. Ruxolitinib (Rux) is a JAK inhibitor approved in intermediate or high risk (HR) MF to improve symptoms and splenomegaly but with little impact on the malignant clone and fibrosis. Interferon alpha (IFNa) can reduce mutant allele burden and fibrosis but is often poorly tolerated in highly symptomatic pts. The RUXOPEG study was designed to assess the efficacy and safety of the combination of Rux + IFNa in MF (NCT02742324). Methods RUXOPEG is a multi-center Bayesian Phase 1/2 adaptive trial. Phase 1 includes up to 9 cohorts of 3 pts with increasing doses of both drugs. Tested doses of Rux and IFNa are 10, 15 and 20 mg BID, and 45, 90 and 135 mcg/week, respectively. Phase 2 will randomize between the 2 best dose combinations selected from phase 1. Primary objective: identify the most efficacious dose combination that also satisfies safety requirements. Primary tolerance criterion is the occurrence of dose limiting toxicities (DLT) within 45 days; primary efficacy criterion is >50% reduction in spleen length within 6 months. Secondary objectives include molecular response, reduction of BM fibrosis, quality of life and symptoms evolution, event-free and overall survival. The planned total enrollment is 42 pts. Key inclusion criteria are: diagnosis of MF (WHO criteria), intermediate or HR (IPSS), need of active therapy, presence of a driver mutation. Key exclusion criteria: prior treatment (or contra-indication) with Rux or IFNa, eligibility for stem cell transplantation, inadequate liver, cardiac or renal function, autoimmune disease, history of depression. Enrolment in 5 cohorts was completed in June 2018, and the last cohort for phase 1 will be opened in August. This abstract reports the current available data for the 5 cohorts who have completed the primary endpoint, but the presentation will provide the detailed analysis of primary and secondary endpoints of phase 1, which will be available in October 2018. Results Among the 15 pts currently enrolled in phase 1, 6 were females, mean age was 60.9 years (range: 38-72), 8 had primary MF, 5 post ET and 2 post PV MF. Median spleen size was 6 cm (range 0 - 18) by palpation and 18 cm (range 10-25) by imaging. Mean (range) blood counts were: hemoglobin 12 g/dL (8.5 - 13.8), WBC 18.3 G/L (8 - 35.5), platelets 457 G/L (157 - 906) and 6 pts had circulating blasts. 12 pts had JAK2V617F and 2 had CALR mutations; karytotype was normal in 9 pts, abnormal in 5 (very HR in 3). In 10 pts analyzed by NGS so far, 8 had additional mutations (1 in 5 pts, 3 in 1, and 4 in 2) in TET2 (n= 5), ASXL1 (4), DNMT3A (2), TP53 (2), SF3B1 (1) and SRSF2 (1) genes. Safety: No DLT was observed in the 5 cohorts (primary safety criterion), the highest tested dose combination being Rux 15 mg BID + IFNa 135 mcg/week. The last cohort will test Rux 20 mg BID + IFNa 135 mcg/week. 4 serious adverse events have been reported: 1 AML transformation (very HR cytogenetics, 3% circulating blasts at baseline), 1 thrombotic event, 1 squamous cell carcinoma and 1 aggravation of Raynaud's phenomenon. Efficacy: preliminary data show a clear decrease in spleen size at 6 months (median 0 cm by palpation, range 0-9; 12.1 cm by imaging, range 10-21) and improvement in blood counts (mean, range): hemoglobin 10.5 g/dL (9.7 - 12.5), WBC 8.6 G/L (5.4 - 11.1), platelets 267 G/L (80 - 486). According to IWG criteria, all the 10 pts evaluable at time of abstract preparation responded (3 partial response, 7 hematological improvement). JAK2V617F allele burden decreased from a mean of 75% (range 43- 96) at baseline to 46% (range 24 - 84) at 6 months. Encouraging results were also found in a patient with 5 mutations (figure1) with a clear decrease in JAK2V617F, ASXL1, DNMT3A and EZH2 mutations after 12 months of treatment. Conclusion RUXOPEG is the first study to formally assess the safety and efficacy of Rux + IFNa combination in MF patients never exposed to either drugs before. The first 5 dose combinations tested showed no DLT, confirming that this combination was generally well tolerated. Preliminary efficacy results are encouraging, including in patients who received very low doses of both drugs. Full results of the 6 cohorts tested in phase 1 and doses selected for phase 2 will be presented. Disclosures Kiladjian: Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; AOP Orphan: Membership on an entity's Board of Directors or advisory committees, Research Funding. Giraudier:Novartis: Research Funding. Cassinat:Novartis: Research Funding; AOP Orphan: Research Funding.

scholarly journals A Phase I/II Study of NMS-03592088, a FLT3, KIT and CSF1R Inhibitor, in Patients with Relapsed or Refractory AML or CMML

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3855-3855
Author(s):  
Marina Ciomei ◽  
Lucia Zanetta ◽  
Federico Lussana ◽  
Erika Ravelli ◽  
Francesco Fiorentini ◽  
...  
Keyword(s):  
Phase I ◽  
Board Of Directors ◽  
Phase Ii ◽  
Research Funding ◽  
Single Agent ◽  
Dose Titration ◽  
Advisory Committees ◽  
Secondary Resistance ◽  
Support Research ◽  
Refractory Aml

Background: NMS-03592088 is a novel, potent inhibitor of the FLT3, CSF1R and KIT receptor tyrosine kinases (KD < 1 nM for all three targets). The compound demonstrated high preclinical efficacy following oral administration in all tested target-dependent tumor models, including those harboring kinase domain secondary resistance mutations, such us the FLT3 residue 691 gatekeeper mutation and the KIT residue 670 and exon 17 mutations. In a FLT3-ITD model of disseminated AML, efficacy observed following single agent treatment with NMS-03592088 was further significantly increased when administered in combination with cytarabine, with excellent tolerability. In preclinical studies conducted in non-human primates, a dose-related increase of circulating CSF1 levels was observed in association with the administration of NMS-03592088, consistent with in vivo inhibition of CSF1R by the compound, thus providing the opportunity for the use of CSF1 levels as a potential pharmacodynamic biomarker of CSF1R modulation in the clinical setting. All three targets of NMS-03592088 are relevant in different settings of hematologic malignancies and solid tumors. In particular, FLT3 mutations occur in approximately 30% of acute myeloid leukemia patients (AML), and are associated with a poor prognosis; KIT mutations are reported in patients with the core-binding factor (CBF) subtype of AML and the CSF1 and/or CSF1R genes are frequently expressed in AML blasts. Recent experimental evidence suggests a potential therapeutic rationale for CSF1R blockade in AML, possibly due to interference with microenvironmental support [Edwards DK et al, Blood, 2019, 133: 588]. Furthermore, chronic myelomonocytic leukemia (CMML) blasts express high levels of CSF1R and NMS-03592088 was able to effectively inhibit their proliferation, concomitant with the suppression of intracellular CSF1R dependent signalling. A clinical trial exploring safety, tolerability and efficacy of NMS-03592088 in patients with AML and CMML is therefore warranted. Trial design: This first-in-human study (EudraCT Number: 2018-002793-47) is designed as an open-label multicenter Phase I/II trial including patients with relapsed or refractory AML or CMML who have exhausted standard treatment options, or for whom standard therapy is considered unsuitable. The study is designed to characterize the safety, tolerability, pharmacokinetics, pharmacodynamics and to explore the preliminary anticancer activity of NMS-03592088 administered orally as single agent once daily for 21 consecutive days, followed by a 7-day break within a 28 day cycle. The study includes an initial conventional phase I part with an accelerated dose titration design in subsequent cohorts of 3+3 patients aimed at defining the maximal tolerated dose (MTD) and the recommended phase 2 dose (RP2D), followed by a limited dose expansion to confirm the RP2D. Once the RP2D is confirmed, a single-stage exploratory Phase II part will start comprising two parallel cohorts, one cohort will consist of AML FLT3 mutated patients and one of patients with CMML. Patients previously treated with FLT3 inhibitors are allowed to participate. The primary endpoint of the Phase II portion of the study is Overall Response Rate. Efficacy will be assessed according to standard criteria [Döhner H et al, Blood 2017, 129: 424; Savona MR et al., Blood, 2015, 125: 1857]. Exploratory endpoints are included to evaluate the potential effects of treatment with NMS-03592088 on circulating levels of CSF1 in plasma, the potential correlation of cellular CSF1R expression levels with clinical outcome in both AML and CMML, and the mutational status of a panel of leukemia-related genes, not limited to FLT3. The Phase I part started in Italy in March, 2019 and is currently ongoing. Disclosures Ciomei: NMS: Employment. Zanetta:Clioss: Employment. Fiorentini:Accelera: Employment. Bosotti:NMS: Employment. Ardini:NMS: Employment. Lombardi Borgia:NMS: Employment. Pulci:Accelera: Employment. Gatto:Clioss: Employment. Di Sanzo:Clioss: Employment. Colajori:Clioss: Consultancy. Davite:Clioss: Employment. Galvani:NMS: Employment. Gan:NMS: Employment. Rossi:Janssen: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Jazz: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria; Mundipharma: Honoraria; BMS: Honoraria; Sandoz: Honoraria; Daiichi-Sankyo: Consultancy; Roche: Membership on an entity's Board of Directors or advisory committees. Rambaldi:Jazz: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau, travel support; Novartis: Membership on an entity's Board of Directors or advisory committees, Other: travel support, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Other: travel support, Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding, Speakers Bureau; Amgen: Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Italfarmaco: Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding, Speakers Bureau; Gilead: Membership on an entity's Board of Directors or advisory committees, Other: travel support, Speakers Bureau; Omeros: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Isacchi:NMS: Employment.

scholarly journals The FLT3 F691L Gatekeeper Mutation Promotes Clinical Resistance to Gilteritinib + Venetoclax (GILT + VEN) in AML

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 2235-2235
Author(s):  
Setareh Sharzehi ◽  
Sunil K Joshi ◽  
Janét Pittsenbarger ◽  
Jeffrey W. Tyner ◽  
Elie Traer
Keyword(s):  
Tyrosine Kinase ◽  
Board Of Directors ◽  
Research Funding ◽  
Immunoblot Analysis ◽  
Tyrosine Kinase Domain ◽  
Resistance Mutations ◽  
Advisory Committees ◽  
Mechanism Of Resistance ◽  
Clinical Resistance

Abstract Background: FMS-like tyrosine kinase (FLT3) is one the most frequently mutated genes in AML and is associated with poor prognosis. FLT3 internal tandem duplication (ITD) and tyrosine kinase domain (TKD) mutations occur in up to 30% and 5-10% of AML, respectively. Several small molecule FLT3 inhibitors (FLT3i) have been developed but their use as single agents is limited due to the development of drug resistance. Our lab developed a two-step model of early and late resistance to FLT3i that recapitulates resistance in AML patients (Traer et al. Cancer Res. 2016; Joshi et al. Cancer Cell 2021). Early resistance, also known as AML persistence, is the stage when residual AML cells are dependent upon the marrow microenvironment for survival and patients are clinically responding. Late resistance to GILT was characterized by expansion of intrinsic mutations, with NRAS mutations being the most frequent mutation, in addition to a few gatekeeper FLT3 mutations. Current therapies are looking at combinations to overcome GILT resistance, including chemotherapy, hypomethylating agents (HMAs), and venetoclax (VEN) +/- HMAs. GILT+VEN, in particular, has shown good initial activity in relapsed/refractory FLT3 AML patients (Daver et al. ASH 2020), however the mechanism of resistance to this combination is unknown. Results: Early resistance cell cultures to GILT+VEN were created by exposing MOLM14 cells to GILT 25nM + VEN 25nM alone or supplemented with microenvironmental ligands FGF2 or FLT3 ligand (FL; N=3/group). Media, drugs, and ligands were replenished twice weekly. After 25 weeks, only the cultures exposed to ligand resumed growth (N=1 for FGF2 and N=3 for FL). Ligands were then removed from these early resistant cultures to induce late resistance. There was an initial drop in cell viability but cells resumed growth after only 3.5 weeks (Fig. 1). In contrast, the time to develop early and late resistance to GILT monotherapy was 8 and 15 weeks, respectively. Immunoblot analysis of GILT + VEN early and late resistant cultures demonstrated restoration of FLT3 signaling, as well as phosphorylation of downstream AKT/MAPK pathways. These results also contrasted to late GILT monotherapy resistant cultures, which had downstream AKT/MAPK activation via outgrowth of NRAS mutations. Since FLT3 appeared to be functionally active, we sequenced FLT3 and found that all early and late GILT + VEN resistance cultures had gatekeeper FLT3 F691L mutations. F691L accounted for only in a minority of resistance cultures to GILT monotherapy. To test if FLT3 signaling was important for resistance, we exposed parental cells to higher concentrations of gilteritinib, which have been shown to partly overcome F691L, as well as the FLT3i FF-10101, which binds FLT3 at a different site and is not affected by the F691L mutation. Both of these approaches restored sensitivity to FLT3i in vitro. As expected, the F691L mutation provided broad resistance to most FLT3i (Fig. 2). To validate this mechanism of resistance in patients, we identified a relapsed FLT3-ITD patient who was treated with GILT monotherapy for 5 months, followed by GILT + HMA for 4 cycles, and then GILT + VEN for resistant proliferative disease. After an initial response to GILT + VEN, the leukemia cells began to increase again in the peripheral blood. A repeat genetic test was ordered and the patient was found to have developed a FLT3 F691L mutation at a high variant allele frequency (Fig. 3). Conclusion: We have developed a robust cell line model of early and late resistance to FLT3i that mimics the timing and expansion of resistance mutations in the clinic. Our model of early and late resistance to GILT combinations can prospectively predict mechanisms of resistance. Although uncommon as a mechanism of resistance to GILT monotherapy, our model and early patient data predicts that F691L mutations are more important for GILT + VEN resistance. Figure 1 Figure 1. Disclosures Tyner: Seattle Genetics: Research Funding; Astrazeneca: Research Funding; Array: Research Funding; Janssen: Research Funding; Takeda: Research Funding; Gilead: Research Funding; Incyte: Research Funding; Petra: Research Funding; Constellation: Research Funding; Genentech: Research Funding; Agios: Research Funding; Schrodinger: Research Funding. Traer: ImmunoGen: Membership on an entity's Board of Directors or advisory committees; Schrodinger: Research Funding; Genentech: Membership on an entity's Board of Directors or advisory committees; Servier/Agios: Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Incyte: Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Secondary Resistance to Lenalidomide in Del(5q) MDS Is Associated with CDC25C & PP2A Overexpression.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 292-292 ◽  
Author(s):  
Alan F List ◽  
Kathy Rocha ◽  
Ling Zhang ◽  
Rami S. Komrokji ◽  
Justine Clark ◽  
...  
Keyword(s):  
Gene Expression ◽  
Drug Resistance ◽  
Board Of Directors ◽  
Nuclear Export ◽  
Research Funding ◽  
Free Ribosome ◽  
Nuclear Staining ◽  
Advisory Committees ◽  
Secondary Resistance ◽  
Cytoplasmic Staining

Abstract Abstract 292 Background: Allelic deficiency for the RPS14 gene impairs differentiation and survival of erythroid progenitors in del(5q) MDS (Nature 2008; 451:335). Nucleolar stress arising from disruption of ribosome assembly fosters MDM2 sequestration by free ribosome components resulting in p53 stabilization and erythroid hypoplasia (Nat Cell Biol 2009; 11:501). We recently reported that reduced gene dosage of the lenalidomide (LEN) inhibitable, haplodeficient phosphatases CDC25C and PP2Acα is a key determinant of drug sensitivity in del(5q) MDS (PNAS 2009; 106: 12974). We now show that shRNA suppression of these genes to levels commensurate with haplodeficiency reinforces p53 accumulation, and that treatment with LEN promotes MDM2-mediated p53 degradation to transition del(5q) clones to G2/M arrest. We hypothesized that emergence of resistance to LEN in del(5q) MDS arises from two possible mechanisms: (1) up-regulation of haplodeficient drug targets or compensatory isotypes, or (2) inactivating mutations of the TP53 or CDC25C genes. Methods: To investigate mechanisms of LEN resistance, we studied sequential bone marrow (BM) specimens obtained at baseline (BL), response to treatment (TR) and treatment failure (TF) from 12 LEN treated patients with Low/INT-1 risk, transfusion-dependent del(5q) MDS. Eleven patients achieved clonal suppression and transfusion independence; 7 patients developed clinical drug resistance with primary clonal recovery. Immunohistochemical (IHC) staining for cdc25-C, -A and -B; PP2A–Ca and p53 were performed using a biotin-streptavidin-horseradish peroxidase method and compared to 6 age-matched controls; intensity of cytoplasmic or nuclear staining in hematopoietic elements was recorded after blinded review. DNA and RNA were extracted from cryopreserved BM mononuclear cells (BM-MNC) or fixed paraffin blocks from BM clot and biopsy sections. Expression of CDC25C splice variants was assessed by RT-PCR and total gene expression by real time (QT)-PCR. Exonic DNA encoding the catalytic [exons 8–14] and nuclear export domains [exon 11] of CDC25C and the DNA-binding domain of TP53 [exons 4–9] was sequenced for gene mutation analysis. Differences in mean values were compared by paired t-test. Results: P53 immunostaining was significantly higher in del(5q) BL specimens compared to controls ( relative expression [RE] 9.6 vs. 0.25; P =0.007). An admixture of nuclear and cytoplasmic staining for p53 and each cdc25 isotype was observed at BL that was largely restricted to erythroid precursors, whereas at TR cdc25-C and -A expression was primarily cytoplasmic, consistent with drug-induced nuclear exclusion. At TR, RE of only cdc25C (BL, 75 vs. TR, 49; P=0.05) and PP2A (29.2 vs. 12.3; P=0.025) was significantly reduced; whereas at TF cdc25C (TR, 43 vs. TF, 166; P=0.003), cdc25A (42.4 vs. 150; P=0.006), PP2A (7.3 vs. 65.6; P=0.028) and p53 (0.92 vs. 25.4; P=0.024) RE significantly increased. Nuclear localization of cdc25C and p53 but not cdc25A predominated at TF, consistent with escape from cdc25C inhibition. QT-PCR confirmed transcriptional up-regulation of CDC25C at TF with a mean 8.8-fold increase in gene expression vs. BL. DNA sequencing revealed no acquisition of somatic mutations within the CDC25C and TP53 exons studied [n=5]. Conclusions: Secondary resistance to LEN in del(5q) MDS is associated with over-expression and activation of the haplodeficient drug-inhibitable phosphatases, cdc25C and PP2A, with consequent restoration of wt-p53 activation. Absence of gene mutations within the coding exons analyzed suggests that transcriptional compensation alone is responsible for drug resistance. Novel agents targeting transcriptional repression of CDC25C may restore LEN sensitivity and merit investigation in drug resistant del(5q) MDS. Disclosures: List: Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Komrokji:Celgene: Research Funding, Speakers Bureau. Lancet:Celgene: Research Funding. Maciejewski:Esai: Membership on an entity's Board of Directors or advisory committees; Celgene: Speakers Bureau. Sekeres:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau.

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