Sunitinib malate, capsules, 12.5 mg, 25 mg and 50 mg (base), Sutent®, March 2007
Public summary document for Sunitinib malate, capsules, 12.5 mg, 25 mg and 50 mg (base), Sutent®, March 2007
Page last updated: 13 July 2007
Public Summary Document
Product: Sunitinib malate, capsules, 12.5 mg, 25
mg and 50 mg (base), Sutent®
Sponsor: Pfizer Australia Pty Ltd
Date of PBAC Consideration: March 2007
1. Purpose of Application
The submission sought a Section 100 Authority Required listing for
the treatment of gastrointestinal stromal tumour (GIST) after
failure of imatinib mesylate due to resistance or
intolerance.
2. Background
This drug has not previously been considered by the PBAC.
3. Registration Status
Sunitinib mesylate was registered by the TGA on 14 September 2006
for the treatment of advanced renal cell carcinoma and
gastrointestinal stromal tumour (GIST) after failure of imatinib
mesylate treatment due to resistance or intolerance.
4. Listing Requested and PBAC’s View
Section 100 Authority required (Special Authority
Program)
Treatment of adult patients with a metastatic or unresectable
malignant gastrointestinal stromal tumour (GIST) after failure of
PBS-subsidised imatinib mesylate treatment due to resistance or
intolerance.
The PBAC did not comment on the restriction.
5. Clinical Place for the Proposed Therapy
GIST is rare visceral sarcoma that arises predominantly in the
gastrointestinal tract. Sunitinib will provide an alternative
treatment for those patients with GIST who cannot tolerate
imatinib, or who have tumours that are resistant to, or become
resistant to, this drug.
6. Comparator
The submission nominated continued use of imatinib mesylate 600 mg
as the main comparator.
See Recommendation and Reasons for the PBAC’s
view.
7. Clinical Trials
The submission presented across-study comparisons of patients in the sunitinib arm
of Trial 1004 and three cohorts of patients (“crossover cohorts”) from three imatinib
trials (Verweij/Zalcberg, Rankin, and Demetri given higher dose imatinib (600 mg or
800 mg) because they had shown tumour progression on imatinib 400 mg. Trial 1004 was
a double-blind, Phase III comparison of sunitinib versus placebo in patients with
metastatic or unresectable GIST having failed on imatinib. The imatinib trials compared
400 mg and 800 mg or 400 mg and 600 mg. No common comparator was available for use.
This method was called an “indirect comparison” in the submission. The PBAC noted
the ESC advice that it was a non-randomised comparison, so could not control for unsuspected
or unknown confounders, and it was an across-study comparison with no common comparator
to serve as an internal control. Both lessened the validity. There was also possible
selection bias in the crossover cohorts because there were substantial numbers of
patients eligible for crossover who did not enter the cohorts.
The PBAC was advised patients enrolled in the trials may not have been representative
of the patients eligible under the requested PBS listing, which did not specify resistance
to 400 mg/600 mg imatinib. The failure doses of imatinib in the sunitinib trial were:
400 mg or less: 19%, 600 mg: 16%, 800 mg 56%, >800 mg 9%. While all the patients in
the cross-over cohorts failed at 400 mg.
The trials published at the time of the submission were as follows:
| Trial/First author | Protocol title/Publication title | Publication citation |
| Study 1004/ Demetri G (2006) Casali (2006) |
Efficacy and safety of sunitinib in patients with advanced gastrointestinal stromal tumour after failure of imatinib: a randomised controlled trial. Updated results from a phase III trial of sunitinib in GIST patients (pts) for whom imatinib (IM) therapy has failed due to resistance or intolerance. |
The Lancet. 2006. 368 1329-38 J of Clin Oncol. 2006 ASCO Annual Meeting Proceedings Part 1. 24 (18S) (Abstract 9513) |
| Zalcberg (2005) |
Outcome of patients with advanced gastrointestinal stromal tumours crossing over to a daily imatinib dose of 800mg after progression on 400mg. |
Eur J of Cancer. 2005. 41 1751-1757 |
| Verweij (2004) |
Progression-free survival in gastrointestinal stromal tumours with high-dose imatinib: randomised trial. |
The Lancet. 2004. 364 1127-134 |
| Rankin (2004) |
Dose effect of imatinib (IM) in patients (pts) with metastatic GIST - Phase III Sarcoma Group Study S0033. |
J of Clin Oncol. 2004 ASCO Annual Meeting Proceedings (Post-Meeting Edition). 22 (14S) (Abstract 9005) |
| Demetri (2002): |
Efficacy and safety of imatinib mesylate in advanced gastrointestinal stromal tumors. |
NEJM. 2002. 347 (7) 472-80 |
8. Results of Trials
The results of the key analysis comparing median progression-free survival (PFS) in
the sunitinib arm of Trial 1004 and the three crossover cohorts are summarised in
the tables below. PFS analyses were time-to-first event comparisons where either progression
or death qualified as an event, and the median PFS values determined from the Kaplan-Meier
curves. Because the Demetri crossover cohort was small (n=9) a separate analysis of
its median PFS compared to the sunitinib arm was not presented.
Median PFS of sunitinib arm (Trial 1004) and three imatinib crossover cohorts
| Patient group (number, number eligible) | Median PFS |
| Sunitinib arm of Trial 1004(n=207) | 24.1 wks |
| Verweij/Zalcberg crossover cohort (n=133 of 247 eligible) | 11.6 wks |
| Rankin crossover cohort (n=88 of 164 eligible) | 17.4 wks |
| Demetri crossover cohort (n=9 of 12 eligible) | 14.5 wks |
| Patient groups being compared | Difference in median PFS |
| Sunitinib – Verweij/Zalcberg | 18.1 wks |
| Sunitinib – Rankin | 6.7 wks |
| Sunitinib – all three crossover cohorts | 9.6 wks |
The relative and absolute risk reductions of the same PFS events in the sunitinib
arm of Trial 1004 compared to the three crossover cohorts are shown below.
Results of relative and absolute risk reduction of progression/death: Sunitinib arm
of Trial 1004 and imatinib crossover cohorts
| Comparison | Relative risk reduction [95% CI] | Absolute risk reduction [95% CI] |
| Sunitinib vs imatinib (Verweij/Zalcberg) | 27.6% [10.6%, 41.3%] | 16.4% [5.7%, 27.1%] |
| Sunitinib vs imatinib (Rankin) | 32.0% [13.6%, 46.5%] | 20.2% [6.9%, 33.5%] |
| Sunitinib vs imatinib (Demetri)* | 35.5% Not done | 23.7% Not done |
| Sunitinib vs imatinib (all) | 29.5% [14.7%, 41.7%] | 18.0% [8.5%, 27.4%] |
*95% confidence intervals were not calculated for Demetri since the approximation
of a binomial distribution by a normal distribution is not good for small numbers.
The submission presented, as clinically supportive, the protocol-specified efficacy
results of Trial 1004 including time-to-progression (the primary outcome), PFS, overall
survival, tumour response, and duration of performance status. At the first efficacy
interim analysis time-to-progression showed statistical significance (p<0.001) in
favour of sunitinib, exceeding the pre-specified significance (p=0.0031). After this
analysis the protocol was amended to enable patients progressing on placebo to switch
to sunitinib. The protocol provision for maintaining a 5% overall risk of false positive
inference included only the time-to-progression analyses. These risk reduction calculations
were made using the same events that contributed to the Kaplan-Meier PFS curves, not
using events based on a time anchored analysis (such as progression at six months).
Both the median PFS results and these results are derived from the Kaplan-Meier curves
so the two should not be viewed as providing independent evidence.
The toxicity profiles of sunitinib and imatinib overall appeared generally similar
although differing in some details. There were few systematic comparative data on
the toxicity of patients who progress despite imatinib. The only randomized trial
of imatinib failures was Trial 1004, comparing sunitinib to placebo. Valid toxicity
data comparing imatinib continuation versus switching to sunitinib could only be obtained
by a trial employing this design.
9. Clinical Claim
The submission claimed sunitinib offers significantly more efficacy
than the main comparator and similar toxicity. The PBAC considered
this claim was not adequately supported in the non-randomised
comparison.
10. Economic Analysis
A preliminary across-trial comparison based economic evaluation was
presented.
The submission acknowledged that on the basis of the claimed
superior efficacy and similar toxicity, that the appropriate type
of economic evaluation would be a cost-effectiveness analysis, but
“in light of some uncertainty regarding the indirect
comparison, due to the lack of imatinib data, the basis of the
submission was one of cost minimisation, with the caveat that
interchangeability is not appropriate, in light of the clear
clinical place of each product. Accordingly the Sponsor sought
listing on a cost minimisation basis.
The cost effectiveness evaluation was based on the yearly cost
being less for sunitinib compared to imatinib. The resources
included were drug costs and costs of managing adverse events. A
cost-effectiveness analysis, based on Trial 1004, comparing
sunitinib and placebo was not provided.
The submission claimed the across trial comparison based
incremental cost/extra PFS year was dominant in the three analyses
presented. A modelled economic evaluation was not presented.
See Recommendations and Reasons for PBAC view.
11. Estimated PBS Usage and Financial Implications
The submission claimed there would be cost savings to the PBS if
listed.
12. Recommendation and Reasons
The PBAC agreed that the clinical evidence submitted in support of
sunitinib came from a well conducted, randomised, double-blind
comparison of sunitinib and placebo in patients with metastatic or
unresectable GIST having failed on imatinib (study 1004). The
primary outcome of this trial was time-to-progression (TTP). At the
first interim analysis, the median TTP was 27.3 weeks for sunitinib
compared with 6.4 weeks for placebo (hazard ratio: 0.329, 95% CI:
0.233, 0.466, p<0.001). The results of the secondary outcome,
progression-free survival, were very similar to the TTP results, a
not-unexpected finding as the large majority of events were
progressions rather than deaths. Overall survival was also
significantly better in the sunitinib than in the placebo group at
the first interim analysis (hazard ratio: 0.491, 95% CI:
0.290-0.831, p=0.007). The Committee acknowledged that the decision
to un-blind the study following the first interim analysis and to
offer sunitinib to all patients on placebo will bias later overall
survival analyses towards the null.
However, the PBAC considered that the submission’s
cost-minimisation comparison with imatinib was inappropriate
because it rests on the inadequately supported assumption that
treatment with imatinib in eligible patients is no better than
placebo. Although imatinib may be an appropriate comparator
according to the 2006 PBAC Guidelines as the therapy likely to be
replaced in practice, the cost-effectiveness of continuing imatinib
at elevated doses in patients with metastatic or unresectable GIST
who have failed imatinib is unknown.
Consequently the PBAC considered that the cost-minimisation
approach taken by the submission was not sufficiently informative.
The PBAC thus decided to defer consideration of this item pending
the provision of further information to demonstrate that sunitinib
is a cost effective treatment for gastro-intestinal tumour (GIST)
after failure of imatinib.
The Committee indicated that a cost-effectiveness analysis against
placebo for best supportive care in patients with GIST who have
failed imatinib, would provide an appropriate basis for determining
the cost-effectiveness of sunitinib.
13. Context for Decision
The PBAC helps decide whether and, if so, how medicines should be
subsidised in Australia. It considers submissions in this context.
A PBAC decision not to recommend listing or not to recommend
changing a listing does not represent a final PBAC view about the
merits of the medicine. A company can resubmit to the PBAC or seek
independent review of the PBAC decision.
14. Sponsor’s Comment
The sponsor has no comment to make.
