It's oncology investors' favorite day of the year. More than 5,000 abstracts for the American Society for Clinical Oncology meeting are now available online. Admittedly, I haven't read all of them yet, but here are a few drugs from big pharma with interesting data that I spotted.

Last year's darling is still a hot topic especially since the PD-1/PD-L1 inhibitors were mostly presenting phase 1 data. We have a lot more data for the drugs that encourage the immune system to attack tumors, and the immuno-oncology drugs still look really good.

Melanoma patients have been taking Bristol-Myers Squibb's (NYSE:BMY) nivolumab since 2008, so we have some substantial long-term survival data with 41% of patients living more than three years. While there wasn't a control group, it seems like a pretty durable response.

We've already seen that the combination of nivolumab and Yervoy works in melanoma, but it appears to be effective in other tumor types as well. In kidney cancer, the combination produced objective responses as high as 39% of patients.

Bristol-Myers Squibb also tested the combination in lung cancer where 22% of patients responded to the combination treatment, including the unconfirmed responses. Merck's (NYSE:MRK) MK-3475, which targets the same pathway as nivolumab, might be working even better with 36% of patients exhibiting a response, again confirmed and unconfirmed.

Of course it's dangerous to compare treatment responses in different clinical trials since they may have enrolled patients with different characteristics. And that goes double for trials without a control arm. We'll have to wait for larger controlled trials to declare a winner, but it's clear the drugs should be tested further in lung cancer.

Treating drug resistant tumors
Because cancer cells tend to be genetically unstable, tumors develop mutations that make them resistant to treatments. Lung cancer tumors, for instance, often develop a mutation called T790M3 in the epidermal growth factor receptor, or EGFR, after taking EGFR tyrosine kinase inhibitors, such as AstraZeneca's (NYSE:AZN) Iressa and Tarceva, sold by Roche and Astellas.

AstraZeneca has a new drug, AZD9291, which appears to work well on tumors with T790M3 mutations. The drug controlled the disease in almost all the patients -- 85 out of 89 -- and 64% of patients showed a response to the drug.

This was only a phase 1 trial, but the results look extremely promising for lung cancer patients that have failed initial treatment.

How good?
We've known that Eli Lilly's (NYSE:LLY) necitumumab drug passed its phase 3 trial since last August. The company said necitumumab plus gemcitabine and cisplatin increased overall survival in lung cancer patients compared to the control regimen of just gemcitabine and cisplatin, but didn't give any data.

Until now.

The triple combination extended overall survival by just 1.6 months, increasing from 9.9 months in the control group to 11.5 months for those that also got necitumumab. The hazard ratio for overall survival was 0.84; put another way, the triple combination improved overall survival by 16%.

While technically an improvement, it's hard to get excited about this data. It's likely enough to get the drug approved. There are side effects -- including abnormally low magnesium levels in patients' blood -- but the FDA is pretty lenient about side effects when it comes to cancer drugs.

It may be difficult for Eli Lilly to make necitumumab a commercial success with a marginal improvement in overall survival.

Best is yet to come
While most of the abstracts are available now, the late breaker abstracts won't be available until the ASCO meeting. I'm looking forward to data from a phase 3 trial testing Bristol's Yervoy after surgery in melanoma patients and the data Merck is using to support the approval of MK-3475 in melanoma patients that have failed Yervoy.

Brian Orelli has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.