The American Society of Clinical Oncology’s ASCO 2013 Annual Meeting began in Chicago May 31 and with it has come a stream of news about clinical trial results for experimental cancer drugs. Below are some of the results. This list will be updated throughout the conference as news warrants.

Merck reported positive preliminary results from an ongoing phase 1b expansion study evaluating its experimental antibody therapy targeting PD-1, lambrolizumab (MK-3475), in patients with advanced melanoma. The company said it expected to initiate late-stage clinical trials of the drug in advanced melanoma and non-small cell lung cancer in the third quarter. The study results, presented at the ASCO meeting, were also published online in the New England Journal of Medicine. The interim overall confirmed response rate for lambrolizumab treatment was 38 percent (range 25–44 percent). Ten percent of patients in this dose group were complete responders. The duration of confirmed responses, as measured after the first 12 week evaluation, ranged from greater than 28 days to up to more than 8 months at the time of the analysis, with 80 percent of responding patients continuing on treatment. See press release

Clovis Oncology reported positive initial findings from an ongoing phase 1/2 study of rucaparib, its experimental PARP inhibitor in development for the treatment of ovarian cancer. The results were presented during a poster session at ASCO 2013. A total of 89 percent of ovarian patients in the trial demonstrated clinical benefit. The company said that genetic analysis of ovarian tumors can help identify patients who would benefit from PARP inhibitor therapy. This includes mutations in the BRCA genes, but other predictive mutations as well. Once Clovis identifies the recommended phase 2 dose, it will commence a late-stage development program in platinum-sensitive ovarian cancer in the second quarter of 2013. See press release

The Genentech subsidiary of Roche said final results from a late-stage study of Avastin plus radiotherapy and temozolomide chemotherapy in patients with newly diagnosed glioblastoma, the most common and aggressive form of primary brain cancer, failed to extend survival in a significant way. The company said these patients did show a significant improvement in progression-free survival compared to those who received placebo plus radiotherapy and temozolomide chemotherapy. An independent review committee assessment of progression free survival showed a 39 percent reduction in the risk of disease worsening or death. Patients in the Avastin arm of the trial vs. placebo suffered greater incidence of certain side effects including bleeding in regions of the body excluding the brain (36.8 percent vs. 19.7 percent), high blood pressure (38.9 percent vs. 12.8 percent), too much protein in the urine (proteinuria; 15.7 percent vs. 4 percent) and blood clots (arterial thromboembolic events; 5.8 percent vs. 1.6 percent). There was also a higher incidence of treatment-related deaths in the Avastin arm compared to the placebo arm (4.3 percent vs. 2.7 percent). See press release

Synta Pharmaceuticals said results from an interim survival analysis of a phase 2b/3 study of the company’s lead experimental drug ganetespib as a second line treatment for patients with advanced non-small cell lung adenocarcinoma showed a combination of the drug with docetaxel improved overall survival and progression free survival compared to docetaxel alone. The results, though, disappointed Wall Street as Sytas’ shares closed down 34 percent in trading June 3. Ganetespib, an Hsp90 inhibitor, demonstrated enhanced improvements in the pre-specified patient population that was selected last year for evaluation in an ongoing late-stage trial. The study found 252 patients treated with ganetespib lived for a median of 9.8 months compared to 7.4 months in the group that received docetaxel alone. Patients that were diagnosed more than six months before the trial showed more dramatic results. Median overall survival for those patients receiving ganetespib was 10.7 months compared to 6.4 months for those receiving docetaxel alone. See press release

Amgen said a late-stage trial of its experimental cancer immunotherapy, talimogene laherparepvec, met its primary endpoint of a statistically significant complete or partial response compared to granulocyte-macrophage colony-stimulating factor, in patients with unresected stage IIIB, IIIC or IV melanoma. The study found that 16 percent of patients treated with the experimental therapy had a complete or partial response for at least six months compared to just 2 percent of patients receiving granulocyte-macrophage colony-stimulating factor. The durable response rates for talimogene laherparepvec were 33 percent in stage IIIB/IIIC, 16 percent in stage IVM1a, and three and eight percent, respectively, for stages IVM1b and IVM1c. The durable response rate with GM-CSF was not higher than four percent in any of the stage subsets. Serious adverse events occurred in 26 percent of talimogene laherparepvec patients and 13 percent of GM-CSF patients. Talimogene laherparepvec has a dual mechanism of action, causing local lytic destruction of tumors while also stimulating a systemic anti-tumor immune response. See press release

Novartis presented late stage trial results of a treatment regimen for women with HER2 positive advanced breast cancer resistant to prior Herceptin treatment. The regimen included everolimus tablets together with trastuzumab and vinorelbine. Final results of the BOLERO-3trial showed that the combination therapy reduced the risk of disease progression by 22 percent, meeting the study’s primary endpoint. Addition of the mTOR inhibitor to trastuzumab and vinorelbine significantly extended progression-free survival when compared to treatment with placebo plus trastuzumab and vinorelbine. Median time to progression was 7 months in the everolimus combination arm and 5.8 months in the placebo combination group. The number of on-treatment deaths and the number of deaths due to adverse events were similar across treatment groups. Everolimus is approved in more than 65 countries to treat postmenopausal women with advanced hormone receptor-positive, HER2 negative breast cancer in combination with exemestane after failure of treatment with letrozole or anastrozole. See press release

Richard Carvajal, medical oncologist at Memorial Sloan-Kettering Cancer Center and lead author on a study using AstraZeneca’s experimental drug selumetinib for treatment of metastatic uveal melanoma, reported significant clinical benefit of the drug for patients with this disease, a benefit that has never been demonstrated with other conventional or investigational agents. Progression-free survival in patients receiving selumetinib was nearly 16 weeks compared to seven weeks for patients receiving temozolomide, the current standard chemotherapy. Nearly 50 percent of patients on selumetinib had tumor shrinkage and overall survival was increased by 1.4 months, whereas no patients on temozolomide had tumor shrinkage. Activating mutations in gnaq and gna11, encoding members of the G-alpha q family of G-protein α subunits, are driver oncogenes in uveal melanoma; more than 85 percent of uveal melanoma patients have one of these mutations as did 84 percent of patients in this trial. As a result of the mutation, abnormal activation of a downstream kinase occurs, and it is this kinase that is inhibited by selumetinib. Though uveal melanoma is rare–there are only 2,500 cases diagnosed in the United States each year–about half of patients will develop metastatic disease, and survival for patients with advanced disease has held steady at nine months to a year for decades. The research was supported by a Conquer Cancer Foundation of ASCO Career Development Award, the National Cancer Institute, Cycle for Survival, and the Fund for Ophthalmic Knowledge. See press release

Bayer Healthcare and Onyx Pharmaceuticals reported that in a trial using Nexavar to treat patients with thyroid cancer the drug extends progression-free survival to 10.8 months, compared to 5.8 months among patients receiving placebo. The late-stage trial found no statistically significant difference in overall survival between the treatment arms, a secondary endpoint. Adverse events that emerged during treatment led to discontinuation in 18.8 percent of patients who received sorafenib, compared to 3.8 percent of patients who received placebo. The trial data will form the basis for regulatory submissions of Nexavar for the treatment of differentiated thyroid cancer resistant to treatment by radioactive idodine. Submission of a supplemental New Drug Application in the United States is planned for mid-year 2013, with additional submissions to follow globally. See press release