Synta Pharmaceuticals (SNTA)

Key Post-2008 Developments

        In February 2009, we suspended our global Phase 3 clinical trial of elesclomol plus paclitaxel in metastatic melanoma, called the SYMMETRY trial, following a meeting of the independent data monitoring committee, or DMC. The DMC noted that while an interim review of the primary endpoint of progression-free survival, or PFS, showed trends that favored the elesclomol arm of the study; the interim analysis of the secondary endpoint of overall survival, or OS, favored the control arm. The DMC report noted that the DMC "cannot be sure whether this is an adverse treatment effect, an effect of differing post-progression (off-study) treatments or a chance effect not relating to the study drugs at all" and that this was a "paradoxical outcome" not foreseen prior to study initiation. The DMC also noted in its report that the OS for the elesclomol arm is in the range of what one would expect for

1

survival rates in large, multinational trials in metastatic melanoma; while the OS for the control arm was somewhat longer than would be expected. Of note is that the OS data from the SYMMETRY trial are not yet mature, in that a relatively small fraction of the total survival events have occurred, meaning that OS results from this trial may change over time. We expect the survival data to mature by the end of 2009.

        Based on the interim review, the DMC recommended that unblinded data be released to us, and that we provide appropriate notification to investigators and patients in order that they could jointly make informed decisions on whether to continue therapy. Following our review of the data and further discussion with the DMC, we decided to suspend the SYMMETRY trial and our other ongoing elesclomol trials, including our trial in prostate cancer and our single-agent dose-escalating trial, pending further analysis of the SYMMETRY trial results. We also notified the Food and Drug Administration, or FDA, of the SYMMETRY trial findings and our decision to suspend all ongoing elesclomol trials. Following our report to the FDA, the FDA concurred with our decision and placed each of these trials on clinical hold.

        In our analysis of the SYMMETRY trial results to date, we have not identified any target organ toxicities or adverse events related to elesclomol that might explain an imbalance of deaths between the two arms. We and our partner for the elesclomol program, GSK, are currently investigating a number of aspects related to the SYMMETRY trial results that will inform our choices for future direction of this program, including whether or not to restart the program in melanoma and/or other cancer indications. Following the suspension of our SYMMETRY clinical trial, in March 2009, we implemented a workforce reduction of approximately 90 positions, to a total employee base of approximately 130 positions, in order to align our workforce with our revised operating plans.

Key Post-2008 Developments

        In February 2009, we suspended our global Phase 3 clinical trial of elesclomol plus paclitaxel in metastatic melanoma, called
the SYMMETRY trial, following a meeting of the independent data monitoring committee, or DMC. The DMC noted that while an interim review of the primary endpoint of progression-free
survival, or PFS, showed trends that favored the elesclomol arm of the study; the interim analysis of the secondary endpoint of overall survival, or OS, favored the control arm. The DMC report noted
that the DMC "cannot be sure whether this is an adverse treatment effect, an effect of differing post-progression (off-study) treatments or a chance effect not relating to the
study drugs at all" and that this was a "paradoxical outcome" not foreseen prior to study initiation. The DMC also noted in its report that the OS for the elesclomol arm is in the range of what one
would expect for

1

survival
rates in large, multinational trials in metastatic melanoma; while the OS for the control arm was somewhat longer than would be expected. Of note is that the OS data from the SYMMETRY trial
are not yet mature, in that a relatively small fraction of the total survival events have occurred, meaning that OS results from this trial may change over time. We expect the survival data to mature
by the end of 2009.

        Based
on the interim review, the DMC recommended that unblinded data be released to us, and that we provide appropriate notification to investigators and patients in order that they
could jointly make informed decisions on whether to continue therapy. Following our review of the data and further discussion with the DMC, we decided to suspend the SYMMETRY trial and our other
ongoing elesclomol trials, including our trial in prostate cancer and our single-agent dose-escalating trial, pending further analysis of the SYMMETRY trial results. We also notified the
Food and Drug Administration, or FDA, of the SYMMETRY trial findings and our decision to suspend all ongoing elesclomol trials. Following our report to the FDA, the FDA concurred with our decision and
placed each of these trials on clinical hold.

        In
our analysis of the SYMMETRY trial results to date, we have not identified any target organ toxicities or adverse events related to elesclomol that might explain an imbalance of
deaths between the two arms. We and our partner for the elesclomol program, GSK, are currently investigating a number of aspects related to the SYMMETRY trial results that will inform our choices for
future direction of this program, including whether or not to restart the program in melanoma and/or other cancer indications. Following the suspension of our SYMMETRY clinical trial, in March 2009,
we implemented a workforce reduction of approximately 90 positions, to a total employee base of approximately 130 positions, in order to align our workforce with our revised operating plans.