David Marin, Imperial College London Early molecular prediction of response to TKI

I do not believe that we have been making the best of molecular monitoring. Molecular monitoring is normally used to assess responses like MR3 and MR4.5 or CMR that are achieved late on therapy (while cytogenetics are used to assess responses early on therapy) The current definitions of molecular response are partially arbitrary and with very little prognostic relevance

One example of this is MR3 (MMR)

Probability of PFS Months from starting imatinib therapy CCyR with no MMR, n=91 CCyR with MMR, n= 41 p= months Marin et al, Blood 2008 PFS is similar in patients with CCyR regardless of the depth of molecular response

PFS similar in patients with CCyR regardless of depth of molecular response Druker BJ, et al. NEJM, 2006;355(25):

PFS is similar in patients with CCyR regardless of depth of molecular response Kantarjian HM, et al. Blood. 2006;108:

Maybe we have the concept of MMR wrong? The real question is: What is the additional reduction in the transcript level that confers survival advantage in patients already in CCyR ?

Patient characteristics (n=282) Characteristics Age Median-yr Range-yr Sex- no.(%) Male Female 157 (55.7) 125 (44.3) Sokal risk group - no.(%) Low Intermediate High 88 (31.8) 111 (40.1) 78 (28.1) Interval since diagnosis – (months) Median Range Chromosomal abnormalities in addition to the Ph chromosome no. (%)16 (6.0) Splenomegaly n (%) Spleen size ≥10cm below the costal margin, n (%) 186 (66.4) 75 (26.8) Marin et al, JCO 2011

48% in CCyR on imatinib 29% in CCyR but not on imatinib 7% alive but not in CCyR 94% 84% 77% 48% 10% death because the CML 6% death non CML Outcome in 282 patients treated with imatinib first line in Hammersmith Hospital Marin et al, JCO 2011

Using appropriate statistical methodology we can identify the cut off in the 12 month transcript level for patients in CCyR that predicts for OS with the maximal sensitivity and specify. BCR-ABL/ABL= 0.53% Marin et al, JCO 2011

166 out of 282 patients who received imatinib as first line therapy were in CCyR at 12 months Transcript level OS (%) EFS (%) >0.1% <0.1% p= p= Marin et al, JCO 2011

166 out of 282 patients who received imatinib as first line therapy were in CCyR at 12 months Transcript level OS (%) EFS (%) >0.1% <0.1% p= p= >0.53% <0.53% p= p< Marin et al, JCO 2011

Can we define robust molecular levels at 3, 6 or 12 month that have prognostic value?

Outcome cut- off (%) Number of patients at risk Eight years probability of the outcome OS ≤9.84 > p< PFS ≤9.54 > p< EFS ≤9.84 > p < CCyR ≤8.58 > p< MR3 ≤2.81 > p< CMR ≤0.61 > p< Patients outcome according to the transcript level measured at 3 month Marin et al, JCO 2011

Probability of survival Time from onset of imatinib therapy (years) BCR-ABL/ABL<9.8% OS= 93.3% BCR-ABL/ABL>9.8% OS= 54% p< Survival for 282 patients treated with imatinib first line at the Hammersmith Hospital according to molecular response achieved at 3 months Marin et al, JCO 2011

Cumulative incidence of CMR Time from onset of therapy (years) 8-year cumulative incidence of CMR on imatinib therapy according to the BCR-ABL transcript level at 3 months. 3-month transcript ratio ≤0.61% (n=57), 8-year CI of CMR of 84.7%, 3-month transcript ratio >0.61% (n=222), 8-years CI of CMR of 1.5% p< Marin et al, JCO 2011

6 month Outcome cut-off (%) Number of patients at risk Eight years probability of the outcome OS ≤1.67 > p< PFS ≤1.73 > p< EFS ≤1.67 > p< CCyR ≤2.70 > p< MMR ≤0.73 > p< CMR ≤0.21 > p< month Outcome cut-off (%) Number of patients at risk Eight years probability of the outcome OS≤0.53 > p< PFS≤0.53 > p< EFS≤ 0.57 > p< MMR≤0.22 > p< CMR≤0.036 > p< Patient outcome according to BCR-ABL transcript level measured at 6 and 12 month Marin et al, JCO 2011

md= md= 4.31 md= 5.22 md= 0.35 md= md= 2.24 BCR-ABL1/ABL1 (log) Comparison of transcript levels in the two overall survival risk groups defined at 3, 6 and 12 month Marin et al, JCO 2011

These cut-offs can be used in other centres when the transcript level is expressed on the international scale We have validated our findings using 95 patients treated with imatinib first line at the Royal Liverpool University Hospital Transcript rationOS 3 month ≤9.84% >9.84% p= month ≤1.67% >1.67% p= month ≤0.53% >0.53% p= Marin et al, JCO 2011

n 3 months BCR-ABL/ABL ratio CCyR (RR) c-CCyRS (RR) OS (RR) No discontinuation %111 Non-haematological toxicity % p= p= p= p=0.6 Haematological toxicity % p< p< p< p<0.001 The predictive value of the transcript level measured at 3 months is not affected by imatinib dose reductions Marin et al, JCO 2011

What is the best moment to identify the poor risk patients?

3 months is the optimal time point to predict a patient’s outcome Off Imatinib CMR BCR-ABL1/ABL1 (log) high transcript level at 3 month low transcript level at 3 month Marin et al, JCO 2011

Results of transcript levels at 3 and 6 months are generally consistent 3 month milestone 9.84% Yes No 77% 23% 6 month (1.67%) 6 month (1.67%) No Yes 66% (L/L) (85%) 11% (L/H) 2% (H/L) 21% (H/H) (91%) Yes

8 year CI of CCyR p<0.001 P<0.001 Low/Low (L/L) Low/ high (L/H) High/Low (H/L) High/High (H/H) P=0.09 (L/L) Low at 3 and low at 6 months (L/H) Low at 3 and high at 6 months (H/H) High at 3 and high at 6 months (H/L) High at 3 and low at 6 months

8 year probability of OS 93.5 % (L/L) 92.4 % (L/H) 55.6 % (H/H) 83.3 % (H/L) P<0.001 (L/L) Low at 3 and low at 6 months (L/H) Low at 3 and high at 6 months (H/H) High at 3 and high at 6 months (H/L) High at 3 and low at 6 months

The same principle applies to patients treated with 2G-TKI after imatinib failure

OS and c-CCyRS in 107 patients treated with dasatinib or nilotinib after imatinib failure 3 months BCR-ABL/ABL <10%, n=77 3 months BCR-ABL/ABL >10%, n=30 Time (years) p=0.02 Probability of OS Time (years) p=0.001 Probability of c-CCyRS Milojkovic et al, Blood 2012

What about first line 2G-TKI?

SPIRIT 2: Study Design Chronic phase CML within 3 months of diagnosis Chronic phase CML within 3 months of diagnosis Arm A Imatinib 400 Arm A Imatinib 400 Arm B Dasatinib 100 Arm B Dasatinib 100 Randomised open label study

Dasatinib patient characteristics N=142 Sex Male, n(%) Female, N(%) 79 (55.6) 63 (44.4) Age Median (range)54.5 (18-82) Sokal risk group Low, n(%) Intermediate, n(%) High n(%) 35 (29.9) 51 (43.6) 31 (26.5) EUTOS risk group Low, n(%) High, n(%) 86 (83.5) 17(16.5) Marin et al, Blood 2012

Time from onset of therapy (months) Cumulative incidence of response CCyR = 91.5% MR3 = 70.1% MR4.5 = 39.1% CMR = 6.5% 24 month cumulative incidences of cytogenetic and molecular responses Marin et al, Blood 2012

Cumulative incidence of CCyR Time from onset of therapy (months) p<0.001 BCR-ABL/ABL >10%, n=11 BCR-ABL/ABL ≤10%, n=117 Cumulative incidence of MR 4.5 Time from onset of therapy (months) p<0.001 BCR-ABL/ABL >10%, n=11 BCR-ABL/ABL ≤10%, n=117 The BCR-ABL1 transcript levels at 3 month strongly predict for the 2 year CI of CCyR, MR3 and, MR4.5 Cumulative incidence of MR 4.5 Marin et al, Blood 2012 CCyR MR4.5

Time from onset of therapy (months) Cumulative incidence of CCyR BCR-ABL/ABL ≤2.26%, n=88 BCR-ABL/ABL >2.26%, n=40 p< Time from onset of therapy (months) Cumulative incidence of MR 4.5 BCR-ABL/ABL ≤0.57%, n=62 BCR-ABL/ABL >0.57%, n=66 p< ….. but the optimal cut-offs may turn out to be lower Marin et al, Blood 2012 CCyR MR4.5

Thanks to: Dragana Milojkovic & John Goldman