Phase III Clinical Trials with Protons: Their importance for Patient Centered Care
for: NCI Workshop on Advanced Technologies in Radiation Oncology: Examining the Evidence
Nov. 30 – Dec.2, 2006
William U. Shipley, MD, FASTRO
Massachusetts General Hospital
Harvard Medical School
Boston, MA.
The Goals of Prospective Clinical Trials
To evaluate innovative treatments for possible benefits or harms in cancer management of patients with specific types and presentations of tumors.
Phase I (or I/II) : Evaluation of the safety and feasibility of an innovative treatment.
Phase II: A single arm trial to evaluate, roughly, cancer control efficacy. This can yield a hypothesis generating result, but not a definitive result.
Phase III or a RCT (Randomized Clinical Trial): To evaluate if the innovative treatment is better (or worse) than standard treatment in cancer control or in morbidity reduction.
The first dose-escalation trialwith Conformal Radiation
Summary of RCTs Comparing Dose Using Protons
Trial Site Accrual Endpoint ResultsMGH 820 T3-4 Prostate 202 DSS No benefit with HD
PROG 85-26 Skull base 432 Local Pendingcontrol
MEEI Uveal 188 Visual acuity No benefit with LDmelanoma retention
PROG 92-13 Meningioma 49 Tumor control No benefit with HD
PROG 95-09 T1-2 Prostate 393 PSA and LC Signif. benefit of dose, not protons
Randomized Dose Trial: PROG 95-09
1996 – 1999
ACR HQ
2 center study• MGH• LLUMC•393 patients
T 1c-2bPSA < 15ng/ml
randomize
70.2 Gy 79.2 Gy
5 year bNED results:
70.2 Gy--- 66%79.2 Gy--- 86% p < 0.001
Late GI Complications
Trial 1 2 3 4 5PROG 79.2 Gy 22 9 1 0 0MDAH 78 Gy 28 19 7 0 0RTOG 79.2 Gy 20 6 1 0 0MSK 81 Gy ND 4 1 0 0
78-81 Gy is safely delivered with3D photons, IMRT or Protons
Intensity Modulated Radiation Therapy
Good news: high dose volume is highly conformal
Bad news: Hot spots within the target volume &The “low dose bath” is large
Proton beam therapy
Good news: high dose volume is highly conformal
Bad news: Beam not sharp at prostate depth &Very sensitive to bone density
Intensity-modulated proton therapy
Good news: Highly conformal
Bad news: Not here yet
There has been a big change in the therapeutic landscape in the last decade for Proton Radiation:
Other forms of conformal radiation now exist
Summary of Clinical Trial Design Issues with Protons in 2006
1. Good comparator RT exists -- highly-conformal photon treatments: IMRT and BT
Median follow-up 5.3 yrs
Brachy
HD Protons
Case Matched comparison: MGH Brachytherapy vs high dose proton beam
Summary of Clinical Trial Design Issues with Protons in 2006
2. More Proton facilities now exist
Proton beam therapy – US treatment centers
Summary of Clinical Trial Design Issues with Protons in 2006
3.New QOL instruments are now available to measure, with greater sensitivity, morbidity reduction using Patient Reported Outcomes (PROs) .
Patient Centered CareThe Need for RCT with Protons
Is Equipoise possible for trials in Radiation Oncology using Protons?
“Equipoise holds that a patient should be enrolled in a RCT only if there is substantial uncertainty about which of the treatments would benefit the patient most”
1. The RTOG experience with RCTs
2. The Pediatric COG experience with RCTs
3. The Proton experience with RCTs
The evaluation of new treatments with Radiation by Phase III trials:
Are they better than standard treatments?
Past RTOG experience reviewed
Soares et al. JAMA 331, 2005
Objective
• Evaluate treatment successes in oncology
• Focus on RTOG: 57 RCTs, 12,734 patients.
• Determine the success rate of innovative treatments by assessing:– Investigators’ conclusions and preferences
– Proportion of RCTs that achieved statistical significance of the primary outcome --- 10%.
Results
• Researchers favored standard treatment in 71% of comparisons
– Many inconclusive trials– 88%.– New treatments--higher morbidity.– New treatments are more costly.– The standards for the adoption of new
practices are high.
RCTs in Pediatric Oncology-- COG
Results: In 53% of the RCTs the investigators’ conclusions favored the standard treatment arm.
In 47% of the RCTs the investigators’ conclusions favored the innovative treatment arm.
A. Kumar et al. BMJ 331: 1295-1301, 2005
Summary of RCT Outcomes
1. In RTOG: In 71% of the RCTs the standard treatment was favored
2. In COG: In 53% of the RCTs the standard treatment was favored
3. With Protons: in only 1 of 4 trials was the innovative arm favored
“The value of new experimental treatments can
not be confidently predicted in advance”
Clinical Trial Design Issues
How often has the “perception” by academic clinicians that an experimental cancer treatment is superior to standard treatment been proven correct?
So infrequently as to make us all humble.
Summary of Clinical Trial Design Issues with Protons in 2006
1. Where Proton radiation no longer has the unique ability to give higher doses to the CTV, its potential clinical advantages of morbidity reduction require testing by RCT using PROs instruments.a. Conventional fractionation
b. Hypofractionation
Summary of Clinical Trial Design Issues with Protons in 2006
2. Only in children is the condition of equipoise for testing Protons Vs. IMRT justifiably questioned.
In children the physiologic rationale for Protons is uniquely great because of the known unique morbidity in children from the transient photon radiation bath. (A decrease in body growth and in brain development plus the especially high rate in children of radiation-induced tumors).
Summary of Clinical Trial Design Issues with Protons in 2006
3. Evaluation of the benefits of Protons compared to elegant forms of conformal photon radiation by RCT is now an opportunity and a responsibility.
Summary of Clinical Trial Design Issues with Protons in 2006
4. RTOG has opened a Proton Investigator Group with Tom DeLaney as chair that will begin by opening some Prostate studies: RTOG 0626 and RTOG 0415.
5. Through the ATC headed by Jim Purdy there is now electronic data transfer for both photons and protons allowing dose distribution comparisons and DVH analyses.
•High technology is great but it is
seductive and it is expensive.
• If all forms of high dose radiation are
equally efficacious, then they need QoL
testing (morbidity reduction by PRO) and
economic analyses to determine their
true justification and appropriate use.
Closing thoughts
