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The Life Raft Group. The Life Raft Group 40 Galesi Drive Wayne, NJ 07470 Phone 973-837-9092 Fax 973-837-9095 Email liferaft@liferaftgroup.org www.liferaftgroup.org. Life Raft Group Relapse Study.
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The Life Raft Group The Life Raft Group 40 Galesi Drive Wayne, NJ 07470 Phone973-837-9092Fax973-837-9095 Email liferaft@liferaftgroup.org www.liferaftgroup.org
Life Raft Group Relapse Study Disease Progression in Patients with Metastatic GIST Receiving Gleevec (Imatinib): The Effect of Drug Dosage
Study Criteria • Metastatic GIST patients • Initial response to Gleevec was shrinkage • On Gleevec one year or more
Objectives Of Our Study • To determine whether there was a correlation between Gleevec dosage and the development of resistance, after one year, amongst metastatic GIST Patients who had initially experienced shrinkage on Gleevec. • To evaluate the difference between using starting dosage (intent to treat) and actual dosage (dosage delivered).
Data Notes • Based upon patient reporting • Adjusted for patient compliance-7 non-compliant patients in study • May be biased by non random distribution • May not be representative of all patients • Some subjectivity in assessment of initial shrinkage and time of relapse • Were not able to distinguish between 600 mg and 800 mg dosage levels due to small numbers
Data Notes-2 • Two patients who said that they had initial shrinkage (one of our study criteria) were excluded from study because the shrinkage was too marginal. • One patient, a clinical trial participant, was excluded from study because he was incorrectly categorized as metastatic GIST (another of our study criteria) when he actually had a cyst. • One patient, a clinical trial participant, has pediatric GIST.
n = 169 • 92 males • 77 females • 78 Relapsed • 91 Stable
Starting dose distributions were close to equal for males and females, with 43% of males and 36% of females on 600 mg or more. Starting Dose Distribution
Starting Dose Relapse Rates Although there was a higher relapse rate for the lower dose group (49.5% versus 41.2%) this was not statistically significant (p = 0.265).
38% of the total group had at least one dosage change. A higher percentage of females (16%) had a net reduction from high to low dose than males (7%) although this was not statistically significant. Dosage Change
Actual Dosage-Total • There was a significantly lower relapse rate overall for higher actual dose versus lower dose: p = .001
There was a significantly lower relapse rate for females alone for higher actual dose versus lower dose: p = .004 There was a non-significant lower relapse rate for males alone for higher actual dose versus lower dose: p = .116 Actual Dosage-Gender
Female Relapse Rate While not statistically significant (due to small numbers), the actual dosage data does suggest a gender difference that needs to be watched in future studies.
Lower dose group had an 8% higher relapse rate based upon starting dose but a 23% higher relapse rate based upon actual dose. Actual vs. Starting Dosage
Relapse rates were relatively consistent in five six month time periods starting with month 13, although the fifth period (37 – 42 months) numbers are still too small. This brings us 42 months out from day one. Six Month Time PeriodActual Dosage
Using the more traditional Kaplan-Meier analysis method • which takes into account length of treatment time • Relapse rates overall and separately by gender were significantly lower for higher dose
Conclusions • When looking at actual dosage, patients on 600 mg or more of Gleevec are significantly more likely to have lower relapse rates than do patients on less than 600 mg. • Actual dosage produces substantially different results than starting dosage.
Our Relapse Study Team • Norman Scherzer, LRG Exec. Director • Jerry Call, Science Coordinator • Pamela Barckett, Medical Rsch Asst. • David Josephy, PhD, Biochemist • Michael Josephy, MSc, Mathematician • Richard Singleton, PhD, Statistician
