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Other endpoints in screening studies for Soft Tissue Sarcomas. Jaap Verweij MD.PhD Dept of Medical Oncology Erasmus University Medical Center Rotterdam The Netherlands. Time. Surrogate Endpoint. Time. Disease. True Clinical Outcome. Intervention. Surrogate Endpoint. True Clinical
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Other endpoints in screening studies for Soft Tissue Sarcomas Jaap Verweij MD.PhD Dept of Medical Oncology Erasmus University Medical Center Rotterdam The Netherlands
Time Surrogate Endpoint Time Disease True Clinical Outcome
Intervention Surrogate Endpoint True Clinical Outcome Disease
Question: If you know of all these ……… (Your Markers!) Would you be able to cure metastatic soft tissue sarcoma (your ultimate aim)? This is just a random selection of photographs. I apologize to anyone who is not listed
Intervention Surrogate Endpoint True Clinical Outcome Disease
p = 0.02 We Should Desist Using RECIST at Least in GIST Robert S. Benjamin, M.D. Department of Sarcoma Medical Oncology The SARCOMA Center
? • How can we find the proof of concept: • early • when tumors do not shrink with treatment
Screening for new drugs in STS • Are we looking at the right spot?
Which endpoint to use in screening for new agents? • Response rate • Progression Free Rate • Progression Arrest Rate • TTP ratio
Response Rate • Advantage: • Response relatively easily measurable • Disadvantage: • Does not take duration into account (DTIC 17%, duration 10 weeks) • Several cytotoxics discarded for response rate, but high SD rate • May not be appropriate for new cytostatic agents
Is stable disease a relevant achievement? i.e: CR+PR+SD vs PD
Progression free rate(2nd line treatment) 100 90 80 70 60 50 40 30 20 10 0 (months) 0 3 6 9 12 15 O N Number of patients at risk : 221 234 47 16 5 1 Inactive agents 136 146 55 18 14 11 Active agents Van Glabbeke et al, EJC 38:543-549,2002
Type of drug N 3 months 6 months Estim. SE Estim. SE Inactive 234 21 % 3 % 8 % 2 % Active 146 39% 4 % 14% 3% All patients 380 28 % 3 % 10 % 2 % Progression free rates (2nd line) Van Glabbeke et al, EJC 38:543-549,2002
Hypothetical tumor evolution during treatment TTP1 TTP2 If TTP2/TTP1 > 1.33: potentially active agent* * Mick et al, Contr.Clin.Trials 21:343-359. 2000
ET-743 as 3rd line treatment inj soft tissue sarcoma Total population Patients without tumor regression but long lasting stable disease ASCO 2003, # 3293
The problem of duration • It could take long to assess • And in screening studies we would like to know early
Using progression rate Set maximum PD rate above which agent will be rejected PD rate of interest will depend on tumor type Tumor RR PD rate breast >30% <20% NSCLC >20% <30% Glioma >10% <40% STS >10% <50% (??)
Progression Arrest* Rates % * Van Oosterom, In: Clinical Management of soft tissue sarcomas. Martinus Nijhoff Publishers, 131-138, 1986
Response versus Symptom benefit rate* Gefitinib in NSCLC Imatinib in GIST
Conclusions Aim of screening studies • To estimate a.s.a.p.if a drug may be useful for patients Endpoint for screening studies • Progression free rates • Progression arrest rates • TTP ratio • Symptom improvement? All of these require proper validation