Del5q MDS When lenalidomide fails

T. Lodewyck Hematology Symposium - March 2015

Case presentation •  53y old female patient is referred for 2nd opinion in 2013

• Diagnosed with low-risk MDS in 2011 •  Resistant to ESA’s •  Chronic red cell transfusions, 2U red cells / 2 weeks at referral

• Past history •  2011: sarcoidosis treated with steroids •  Chronic renal failure (CrCl 40ml/min)

Case: reassessment •  Laboratory

•  Macrocytic anemia (Hb <8g/dL) •  Normal leucocyte en platelet count •  Normal LDH

• Bone marrow examination •  Hypercellular •  Hypolobulated MK •  Blast <5%

Case: diagnosis 5q- syndrome

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The SpectrumOrange-labeled LSI EGR1 probe, approximately 209 kb in length, is located at 5q31

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The SpectrumGreen-labeled LSI D5S23, D5S721 probe, approximately 561 kb in length, is

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• Cytogenetics: 46,XX,del(5q)(q14;q34) •  FISH: heterozygous del5q in 50% of cells

Common deleted regions in del5q MDS

The majority of genes mapping to the CDR of the 5q!syndrome at 5q32-q33 show a reduction in expression levelsconsistent with the deletion of one allele in patients with the 5q!syndrome.25 Candidate genes identified as showing haploinsuffi-ciency in the HSCs of patients with the 5q! syndrome byBoultwood and colleagues25 include the tumor suppressor geneSPARC and RPS14. Moreover, 2 genes mapping to the CDR,RBM22, and CSNK1A1 showed a reduction in gene expression of" 50% in some patients with the 5q! syndrome, consistent withthe down-regulation of the remaining allele.25 The RBM22 gene,encoding a highly conserved RNA-binding protein, is the mostsignificantly down-regulated gene mapping to the CDR of the 5q!syndrome. RBM22 has been shown to play a role in the regulationof gene splicing and apoptosis.30

Several genes including SPAG6, WIG-1, and BMI-1 are com-monly up-regulated in the CD34# cells of patients with the 5q!syndrome.25 Interestingly, WIG-1, a p53-induced gene, encodes agrowth inhibitory protein,31 BMI-1 is necessary for maintenance ofadult self-renewing HSC,32 and SPAG6 is markedly overexpressedin pediatric AML.33

Several significantly deregulated canonical gene pathways in theCD34# cells of patients with the 5q! syndrome have been identifiedincluding Wnt/$-catenin signaling, protein ubiquitination, aminoacyl-tRNA biosynthesis, cell cycle:G1/S checkpoint, actin cytoskeletonsignaling pathways,25 and most recently the p53 pathway.34

Candidate genes and disease mechanisms

RPS14

The RSP14 gene is a strong candidate gene for the 5q! syndromebased on evidence from several sources.35,36 The small subunitprotein rpS14, the yeast homologue of the bacterial S11 protein,directly binds helix 28 of 18S rRNA and is essential for theassembly of 40S ribosomal subunits.37,38 The yeast ribosomalprotein rpS14 is necessary for the endonucleolytic cleavage thatremoves 200 nucleotides from the 3% end of 20S pre-rRNA togenerate mature 18S rRNA and functional 40S ribosomal sub-

units.39 Upon depletion of rpS14, ribosomal proteins and rRNAdestined for 40S subunits are rapidly degraded, whereas 60S subunitsassemble at normal rates.38 The specific function of RPS14 inhumans remains largely unknown; however, it is most probable thatRPS14 is essential for the assembly of 40S ribosomal subunits.

Haploinsufficiency for RPS14 in the CD34# cells of patientswith the 5q! syndrome and the analogy with Diamond–Blackfananemia (DBA) was noted some years ago.25,35 DBA is a disordercaused by haploinsufficiency for the related ribosomal gene RPS19(also required for the maturation of 40S ribosomal subunits).40

DBA is a broad developmental disease characterized by anemia,bone marrow erythroblastopenia, and an increased malignancy.41

Mutations in RPS19 are found in approximately 25% of patientswith DBA and lead to haploinsufficiency of RPS19.40 RPS19protein and mRNA analysis confirm that expression from thenormal RPS19 allele is not sufficient to compensate for thedefective allele.40 Deficiency of RPS19 has been shown to blockproliferation of immature erythroid progenitor cells.42 Interest-ingly, DBA has been associated with mutations now in 7 ribosomalprotein genes, RPS19, RPS24, RPS17, RPL35A, RPL5, RPL11, andRPS7, in approximately 43% of patients.43

The anemia in DBA and the 5q! syndrome is a result of afailure of erythropoiesis, and both disorders show haploinsuffi-ciency for ribosomal proteins RPS19 and RPS14, respectively,required for the maturation of 40S ribosomal subunits. The pivotalreport from Ebert et al35 in 2008 identified RPS14 as a 5q!syndrome gene by an RNA interference screen of each gene withinthe CDR. RNA interference allows the functional characterizationof deletions in leukemia, modeling hemizygous or homozygousinactivation depending on the efficacy of knockdown. The develop-ment of short hairpin RNA (shRNA) lentiviral expression vectorsenables the use of RNA interference in both quiescent andproliferating progenitor cells. Three to 5 unique, lentivirallyexpressed shRNAs targeting each of the 40 genes in the region wereintroduced into normal CD34# human bone marrow hematopoieticcells, and the effects of each shRNA on hematopoietic differentia-tion were determined. The knockdown of RPS14 recapitulated the

Figure 1. Chromosomal map of human 5q showing the positions ofthe CDRs in myeloid malignancies and corresponding mousemodels.

ADVANCES IN THE 5q! SYNDROME 5805BLOOD, 23 DECEMBER 2010 ! VOLUME 116, NUMBER 26

RPS14 = Ribosomal Protein Subunit 14

Haplodeficiency RPS14 causes p53 overexpression

MDM2 is a key negative regulator of p53 p53 overexpression leads to cell cycle arrest (G1 phase)

Lenalidomide is effective in del5q MDS Plenary paper

A randomized phase 3 study of lenalidomide versus placebo in RBCtransfusion-dependent patients with Low-/Intermediate-1-risk myelodysplasticsyndromes with del5qPierre Fenaux,1 Aristoteles Giagounidis,2 Dominik Selleslag,3 Odile Beyne-Rauzy,4 Ghulam Mufti,5 Moshe Mittelman,6

Petra Muus,7 Peter te Boekhorst,8 Guillermo Sanz,9 Consuelo del Canizo,10 Agnes Guerci-Bresler,11 Lars Nilsson,12

Uwe Platzbecker,13 Michael Lubbert,14 Bruno Quesnel,15 Mario Cazzola,16 Arnold Ganser,17 David Bowen,18

Brigitte Schlegelberger,17 Carlo Aul,2 Robert Knight,19 John Francis,19 Tommy Fu,19 and Eva Hellstrom-Lindberg,20

for the MDS-004 Lenalidomide del5q Study Group

1Hopital Avicenne, Assistance Publique–Hopitaux de Paris, Universite Paris XIII, Bobigny, France; 2St Johannes Hospital, Duisburg, Germany; 3AZ St-JanBrugge AV, Brugge, Belgium; 4Centre Hospitalier Universitaire Purpan Pavillion de Medecines, Toulouse, France; 5King’s College Hospital, London, UnitedKingdom; 6Tel Aviv Sourasky Medical Center, Tel Aviv, Israel; 7Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; 8Erasmus MedicalCenter, Rotterdam, The Netherlands; 9Hospital Universitario La Fe, Valencia, Spain; 10Hospital Universitario de Salamanca, Salamanca, Spain; 11CentreHospitalier Universitaire Nancy Hematologie et Medecine Interne, Vandoeuvre, France; 12Skåne University Hospital, Lund, Sweden; 13Universitatsklinikum CarlGustav Carus, Dresden, Germany; 14University of Freiburg Medical Center, Freiburg, Germany; 15Centre Hospitalier Regional Universitaire Claude HuriezService des Maladies du Sang, Lille, France; 16Department of Hematology Oncology, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico PoliclinicoSan Matteo, University of Pavia, Pavia, Italy; 17Hannover Medical School, Hannover, Germany; 18St James’s Institute of Oncology, Leeds, United Kingdom;19Celgene Corporation, Summit, NJ; and 20Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden

This phase 3, randomized, double-blindstudy assessed the efficacy and safety oflenalidomide in 205 red blood cell (RBC)transfusion-dependent patients with Inter-national Prognostic Scoring System Low-/Intermediate-1-risk del5q31 myelodys-plastic syndromes. Patients receivedlenalidomide 10 mg/day on days 1-21(n ! 69) or 5 mg/day on days 1-28 (n ! 69)of 28-day cycles; or placebo (n ! 67).Crossover to lenalidomide or higher dosewas allowed after 16 weeks. More pa-tients in the lenalidomide 10- and 5-mg

groups achieved RBC-transfusion inde-pendence (TI) for > 26 weeks (primaryendpoint) versus placebo (56.1% and42.6% vs 5.9%; both P < .001). Medianduration of RBC-TI was not reached (me-dian follow-up, 1.55 years), with 60% to67% of responses ongoing in patientswithout progression to acute myeloid leu-kemia (AML). Cytogenetic response rateswere 50.0% (10 mg) versus 25.0% (5 mg;P ! .066). For the lenalidomide groupscombined, 3-year overall survival and AMLrisk were 56.5% and 25.1%, respectively.

RBC-TI for > 8 weeks was associatedwith 47% and 42% reductions in the rela-tive risks of death and AML progressionor death, respectively (P ! .021 and .048).The safety profile was consistent withprevious reports. Lenalidomide is benefi-cial and has an acceptable safety profilein transfusion-dependent patients withLow-/Intermediate-1-risk del5q myelodys-plastic syndrome. This trial was registeredat www.clinicaltrials.gov as #NCT00179621.(Blood. 2011;118(14):3765-3776)

Introduction

International Prognostic Scoring System (IPSS)1 Low- or Intermediate-1-risk myelodysplastic syndromes (MDS) with a 5q deletion (del5q)cytogenetic abnormality is characterized by macrocytic anemia andshort response duration when treated with erythropoiesis-stimulatingagents.2-4 Anemia negatively affects quality of life (QoL) and diseasecourse,5 with red blood cell (RBC) transfusion dependency and subse-quent iron overload associated with poor outcomes in patients withMDS.6,7

Lenalidomide is an immunomodulatory agent with multiplemechanisms of action, which are thought to include the directtargeting of MDS clones, immunomodulation, erythropoiesis resto-ration, and angiogenesis inhibition.8-11

In a phase 2 study of lenalidomide 10 mg in 148 RBCtransfusion-dependent patients with IPSS Low- or Intermediate-1-risk MDS with del5q31, with or without additional cytogenetic

abnormalities, 67% of patients achieved RBC transfusion indepen-dence (TI) for ! 8 weeks, and 73% (62 of 85) experiencedcytogenetic improvement, including 45% (38 of 85) completecytogenetic remissions.12 However, because this was a single-armstudy, comparisons with placebo could not be made.

The current phase 3 study is the first randomized, placebo-controlled study of lenalidomide in MDS. It compares the efficacyand safety of lenalidomide (10 mg and 5 mg) against placebo inRBC transfusion-dependent patients with IPSS Low- or Intermediate-1-risk MDS with del5q31.

MethodsThis phase 3, multicenter, randomized, double-blind, placebo-controlledstudy enrolled patients from July 8, 2005 to June 26, 2007 at 37 study sites

Submitted January 19, 2011; accepted June 20, 2011. Prepublished online asBlood First Edition paper, July 13, 2011; DOI 10.1182/blood-2011-01-330126.

An Inside Blood analysis of this article appears at the front of this issue.

The online version of this article contains a data supplement.

The publication costs of this article were defrayed in part by page chargepayment. Therefore, and solely to indicate this fact, this article is herebymarked ‘‘advertisement’’ in accordance with 18 USC section 1734.

© 2011 by The American Society of Hematology

3765BLOOD, 6 OCTOBER 2011 ! VOLUME 118, NUMBER 14

responses and had been censored. Median duration of protocol-defined RBC-TI (! 26 weeks) was not reached.

Subgroup analysis of erythroid response (lenalidomide10 mg vs 5 mg)

RBC-TI for ! 26 week rates (mITT population) favored lenalido-mide 10 mg over 5 mg for most subgroups (Figure 3). In45 lenalidomide-treated patients with baseline EPO levels! 500 mIU/mL, the RBC-TI rate was significantly higher withlenalidomide 10 mg versus 5 mg (76.2% vs 33.3%; P " .004).

Predictors of erythroid response

A multivariate analysis based on a logistic regression modelshowed that factors significantly predictive of RBC-TI for! 26 weeks were lenalidomide treatment (P # .0001 for lenalido-mide 10 mg vs placebo; P " .0004 for lenalidomide 5 mg vsplacebo), higher baseline platelet count (! 150 $ 109/L; P " .003),and longer time since MDS diagnosis (! 2 years; P " .05).

Change in hemoglobin levels

Figure 4 shows changes from baseline in hemoglobin levels (mITTpopulation). Median maximum hemoglobin increases in patientswho responded to lenalidomide (RBC-TI for ! 8 weeks) were6.3 g/dL (range, 1.8-10.0 g/dL) with 10 mg and 5.2 g/dL (range,1.5-8.5 g/dL) with 5 mg.

Cytogenetic response and progression

Cytogenetic response rates (complete % partial) in the mITTpopulation were 50.0% and 25.0% in the lenalidomide 10 mg and

5 mg groups, respectively (P " .066). Complete cytogenetic re-sponse rates were 29.4% and 15.6% (P " .29). No cytogeneticresponses occurred in the placebo group (P # .001 vs bothlenalidomide groups). Cytogenetic progression (development ofnew independent clones as well as additional aberrations togetherwith del5q31) was observed in 8 of 34 lenalidomide 10 mg patients(23.5%; P " .50 vs placebo), 10 of 32 lenalidomide 5 mg patients(31.3%; P " .17 vs placebo), and 5 of 35 placebo patients (14.3%).Similar results were observed in the ITT population (data notshown). Median time to cytogenetic progression was 93 days(range, 85-170 days) in the lenalidomide 10 mg group, 85 days(range, 83-339 days) in the lenalidomide 5 mg group, and 99 days(range, 83-172 days) in the placebo group.

HRQoL

Baseline and week 12 (ie, before crossover) FACT-An scores wereavailable for 71% of randomized patients (lenalidomide 10 mg,n " 48; 5 mg, n " 45; placebo, n " 52). Baseline scores (mean& SD) were 121.1 & 21.3, 124.8 & 25.0, and 121.5 & 28.0 amongthe lenalidomide 10 mg, 5 mg, and placebo groups, respectively.Mean change from baseline at week 12 was significantly higher forlenalidomide 10 mg (5.8 vs '2.5; F " 4.25; P # .05) and 5 mg (5.9 vs'2.5; F " 4.18; P # .05) versus placebo. Absolute change frombaseline FACT-An scores exceeded 7 points (ie, minimal clinicallyimportant difference) among RBC-TI ! 26 week responders at weeks12, 24, 36, and 48 in both lenalidomide groups (Figure 5).

Disease progression

In the safety population, median duration of follow-up for AMLprogression (from date of randomization to AML, death, or last

Table 3. Erythroid response, as assessed by RBC-TI for > 26 weeks or > 8 weeks (double-blind phase; mITT and ITT populations)

RBC-TI, n (%) (95% CI)

Placebo Lenalidomide 5 mg Lenalidomide 10 mg

mITT population n ! 51 n ! 47 n ! 41Protocol defined (! 26 wk) 3 (5.9) (1.2-16.2) 20 (42.6) (28.3-57.8)* 23 (56.1) (39.7-71.5)*

IWG 200013 (! 8 wk) 4 (7.8) (2.2-18.9) 24 (51.1) (36.1-65.9)* 25 (61.0) (44.5-75.8)*

IWG 200614 (! 8 wk) 3 (5.9) (1.2-16.2) 24 (51.1) (36.1-65.9)* 25 (61.0) (44.5-75.8)*

ITT population n ! 67 n ! 69 n ! 69Protocol defined (! 26 wk) 4 (6.0) (1.7-14.6) 24 (34.8) (23.7-47.2)* 38 (55.1) (42.6-67.1)*

IWG 200013 (! 8 wk) 5 (7.5) (2.5-16.6) 33 (47.8) (35.6-60.2)* 42 (60.9) (48.4-72.4)*

IWG 200614 (! 8 wk) 4 (6.0) (1.7-14.6) 33 (47.8) (35.6-60.2)* 42 (60.9) (48.4-72.4)*

*P # .001 versus placebo.

Figure 2. Duration of IWG 2000-defined13 RBC-TI in patients random-ized to lenalidomide (LEN) 10 mg or 5 mg (mITT population). Figurerepresents patients who achieved RBC-TI during the double-blind phaseof the study. For duration of RBC-TI, data are included until the last datewith available information on transfusions. This date is indicated ascensored for patients who died or who remain RBC-TI at data cut-off.Median duration of RBC transfusion follow-up for all treatment groupscombined was 1.55 years (RBC transfusion follow-up for ! 1, ! 2, and! 3 years was available for 85, 54, and 9 patients, respectively).

LENALIDOMIDE IN TRANSFUSION-DEPENDENT del5q MDS 3769BLOOD, 6 OCTOBER 2011 ! VOLUME 118, NUMBER 14

Median time to response 4 weeks

Lenalidomide acts through PP2A inhibition

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START STOP LENALIDOMIDE after 4 cycles

Primary resistance to lenalidomide • Bone marrow: blast <5%

•  FISH: del5q in 50% of cells, comparable to diagnosis

• Cytogenetics: no additional chromosomal abnormalities

èNo evidence for disease progression or clonal evolution

Primary resistance to lenalidomide •  p53 nuclear staining by immunohistochemistry (IHC)

•  p53 mutation detected (c.533A>C(p.His178Pro); exon 5)

Primary resistance results from TP53 mutations

• Using next-generation sequencing it has been shown that about 20% of isolated del5q MDS cases harbor TP53 mutations at diagnosis

• Presence of TP53 mutations correlates with •  Low risk of achieving cytogenetic response to lenalidomide •  Increased transformation to AML •  Inferior overall survival •  By contrast, comparable erythroid response rates to lenalidomide

•  TP53 mutations correlate with strong p53 staining by IHC

Kulasekararaj A. BJH 2013;160: 660-672 Jädersten M. JCO 2011; 29: 1971-1979

Strong nuclear p53 staining by IHC as a surrogate marker for TP53 mutations

Strong p53 protein expression in a subset of bone marrow samples

A total of 30 of 85 patients (35%) had !1% BM progen-itor cells with strong (3+) p53-DO1 expression in the ini-tial screening sample: !1% to <2% in 14 patients; 2% to<5% in 11 patients; and !5% in five patients. Figure 1shows an example of p53 staining.

Detailed clinical and morphological data for the IHCstudy cohort are presented in Online Supplementary TableS2. All samples with !1% strong p53-staining by IHCwere subsequently double-stained for CD34, hemoglobin,glycophorin A, and myeloperoxidase. p53 was predomi-nantly expressed in erythroid progenitor cells, but also inthe granulopoietic cell lineage and in rare cases inmegakaryocytes; the latter was only seen in patients withrefractory anemia with excess blasts-1. None of the sam-ples with secondary, non-MDS related cytopenia showedstrong p53 staining.

Strong p53 expression reflects the TP53 gene mutationTP53 sequencing analysis was performed in a subset of

nine (11%) patients in the IHC study cohort from whomadditional consent was obtained (Online SupplementaryTable S4). Mutations were detected in three patients:C275F and E294K missense mutations were associatedwith strong p53 expression, whereas the K291* nonsensemutation was negative by IHC. In one patient (patient 37)the mutation was acquired at a later time point which wasreflected by positive IHC, whereas previous samplesstained negative. In the remaining six patients withoutTP53 mutations, IHC was negative in four, whereas twopatients had 1.2% and 1.6% BM progenitor cells withstrong p53 expression. However, it should be noted thatthe material used for sequencing was whole BM sectionswhich made this method less sensitive than previous stud-ies using archived BM smears.10 In seven patients, P72R

polymorphisms were identified. These are known TP53polymorphisms that do not represent gene mutations andwere negative by IHC, as expected.

Single-cell laser-microdissection was performed in serialBM samples from three patients to assess the relationshipbetween the degree of p53 protein expression and muta-tion. Of these, patient 34 was also part of the IHC cohort(Figure 2). The mutational allelic burden in microdissectedcells with strong (3+) p53-staining was around 45%, indi-cating that 90% of the cells carried the mutation. In con-trast, cells from the same sample with moderate (2+) p53-staining predominantly had wild-type TP53 (allelic burdenaround 16%). Online Supplementary Figure S2A-C showsserial data from these three patients, including the correla-tion between the percentage of strong (3+) p53-stainingcells and the allelic burden by pyrosequencing analysis.Online Supplementary Figure S2D shows data for patient 37,obtained by deep-sequencing using DNA from whole BMsections.

Strong p53 expression predicts shorter overall survivaland higher risk of developing acute myeloid leukemia

The impact of strong p53-staining on outcome was sepa-rately assessed for the presence of any strong p53-stainingcells versus none, for !1% and !2% cutoffs, and for thewhole IHC cohort by <1% (n=55), !1% to <2% (n=14),and !2% (n=16). As the !1% to <2% and !2% curves forboth overall survival and progression to AML were similar-ly associated with worse outcome (overlapping) and wellseparated from the <1% curve (Online Supplementary FiguresS3 and S4), the 1% cutoff was used for all subsequentanalyses, with !1% defined as “p53-positive” and <1% as“p53-negative”. Baseline demographics, clinical data, andWorld Health Organization subgroups did not differ signif-icantly between patients with !1% (n=30) and <1% (n=55)strong p53-staining (Online Supplementary Table S5).

p53 protein expression predicts outcome in MDS

haematologica | 2014; 99(6) 1043

Figure 1. The p53-DO1 stainshows cells with moderate (2+)and strong (3+) nuclear staining(top). The lower left panel showsa BM sample with only scatteredstrong p53-positive staining (redcircle) around the 1% level byboth manual and automatedimage assessment. The lowerright panel shows a BM samplewith the presence of scatteredweak (1+; yellow circle) and mod-erate (2+; orange circle) p53-pos-itive staining cells, but no cellswith strong (3+) nuclear staining.

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Saft L. Haematologica 2014; 99:1041

The median overall survival was 2.4 years (interquartilerange [IQR] 1.7-3.7) and 4.3 years (IQR 3.5-6.4) in p53-positive and p53-negative patients, respectively(P=0.0175) (Figure 3). The 5 year rates to AML progressionwere 56.3% (IQR 33.3-79.3) and 19.6% (IQR 7.1-32.2),respectively (P=0.0006) (Figure 4). The 5-year rates toAML progression using death without AML as a compet-ing risk were 41.3% (IQR 23.0-58.8) and 14.5% (IQR 6.7-25.2), respectively (P=0.0021). Similarly, p53 IHC positivi-ty was significantly associated with worse outcomes(overall survival and AML risk) in patients randomized tolenalidomide (n=60); 21 of 60 patients (35%) who received

lenalidomide had !1% strong p53-staining cells comparedwith nine of 25 patients (36%) who received placebo(Online Supplementary Table S2). For patients randomizedto lenalidomide (n=60), the median overall survival was2.0 years (range, 1.2-5.0) and 4.1 years (range, 2.9-5.7) inp53-positive and p53-negative patients, respectively(P=0.0830). The 5-year rates to AML progression were51.3% (IQR 25.2-77.4) and 20.8% (IQR 5.3-36.3) for p53-positive and p53-negative patients, respectively(P=0.0047); the 5-year rates to AML progression usingdeath without AML as a competing risk were 39.8% (IQR18.3-60.8) and 15.4% (IQR 6.1-28.6), respectively

L. Saft et al.

1044 haematologica | 2014; 99(6)

Figure 2. Laser-microdissectionof BM cells with strong (3+; redcircle), moderate (2+; orangecircle), and negative p53-stain-ing collected in three separatetubes from the same formalinfixed, paraffin-embedded BMsample (patient 34, BM sampleat 105 months from initial diag-nosis). TP53 mutation analysisby pyrosequencing using DNAfrom microdissected cells. Theimages were taken with a LeicaLaser Microscope at 60! mag-nification before (left) and after(right) laser-microdissection;p53-negative microdissectedcells are not shown in the upperimages. Patient 34 had classi-cal 5q" syndrome [46, XX,del(5q)] with a previouslyknown C275F (G>T) TP53mutation.

Figure 3. Overall survival bythe presence of <1% (p53-negative) and #1% (p53-posi-tive) BM progenitor cells withstrong (3+) p53 staining.

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Strong p53 staining in ≥1% of cells confers poor outcome

Del5q MDS When lenalidomide fails …

Think TP53!