GlaxoSmithKline will be disappointed by the news that partner Synta Pharmaceuticals has suspended a late-stage trial of its skin cancer drug elesclomol, a move which saw the Massachusetts-based firm’s stock collapse.

Synta said it has stopped the Phase III Symmetry trial comparing elesclomol in combination with paclitaxel to paclitaxel alone in chemo-naive patients with stage IV metastatic melanoma. The decision was taken after an independent data monitoring committee identified safety concerns, notably a greater number of deaths in patients on the elesclomol/paclitaxel arm.

The company added that the final analysis of the primary endpoint as assessed by independent reviewers has not been carried out yet. Chief medical officer Eric Jacobson said “we are enormously disappointed for melanoma patients, particularly because there are so few treatment options available’, and Synta also noted that ongoing studies with elesclomol, including one in combination with docetaxel in hormone-refractory metastatic prostate cancer, have also been suspended.

The market seems to have decided that elesclomol is finished and Synta shares fell 79% to $1.36. Brokers rushed to downgrade the stock and one, RBC Capital Markets' Jason Kantor, wrote an investor note saying that the suspension of elesclomol development due to safety issues “represents the worst-case scenario. He added that "we now assign zero value to this programme and expect significant expense reductions to conserve cash”.

Synta is going to discuss the next move with GSK but analysts expect the UK drug major to pull out of the deal. Earlier this month, GSK paid out $10 million as part of the partnership the two companies entered into in October 2007 and Synta has now received $130 million.

Avodart ads misleading, says FDA
Meantime, GSK has been sent a warning letter from the US Food and Drug Administration saying that a television advertisement for Avodart (dutasteride), for the treatment of benign prostatic hyperplasia (BPH), "makes misleading comparative claims” and overstates its efficacy.

The agency said that GSK’s Planetarium promotion suggests that Avodart is the only treatment available that "shrinks the prostate." However, Merck & Co's Proscar (finasteride), which is also available generically, does reduces prostate size, the FDA said.

The agency added that it is” not aware of any comparative clinical trials of Avodart monotherapy and other products approved for the treatment of BPH to support the implication that Avodart is superior". A GSK spokeswoman noted that the advert has not aired since September and the company will ensure that future advertising for Avodart “integrates the direction provided to us by the FDA".