I was looking at this company because I think they are a good comparison to THTX. They are developing an ADC to a unique target primarily in ovarian and lung cancer.
It seems lately the program has been underperforming as described here
https://www.evaluate.com/vantage/articles/news/snippets/mersanas-upri-disappoints-again
although an analyst has a much rosier view
https://www.svbleerink.com/wp-content/uploads/2020/02/MRSN-Time-2B-Gr8.pdf
The SP is around $4 and market cap of $300-$400 million but the SP has been all over the place in recent years going as high as $27.
The biggest reason I'm posting is because that analyst report has a bit about the benchmark for approval in late line ovarian cancer. It's surprisingly low, their estimate an ORR of ~15%. It's certainly not this low for other cancers. Here's the bit from p17 of the report.
"Benchmark prOC response rates: dose expansion (1-3 prior therapies)
According to one KOL we spoke with, a response rate in prOC (1-3 priors) of ~20-25% and PFS of ~7 months would be viewed as a win. The KOL also added that the drug would need to demonstrate a manageable toxicity profile, which he believes XMT-1536 would certainly fit (based on the data to date).
A second KOL believes the historical experience in patients with 1-3 priors has been an ORR of ~15%, and his benchmark ORR would be any response rate with non-overlapping confidence intervals. According to this KOL, a point-estimate response rate in the dose expansion population (those with 1-3 priors) where a 95% confidence interval did not overlap with 15% would be considered the benchmark for new therapies.
The FDA’s recent guidance to IMGN (MP) indicates a response rate of ~12% is considered the benchmark for single agent chemotherapy in prOC patients treated with 1-3 priors (2L- 4L). IMGN is also developing an ADC, mirvetuximab soravtansine, which targets folate receptor alpha (FR-α) in prOC. IMGN’s registrational strategy for mirvetuximab soravtansine involves a single-arm, pivotal study (SORAYA) to support accelerated approval, with a confirmatory Phase III study (MIRASOL) comparing mirvetuximab to investigator’s choice chemotherapy. While MRSN had previously suggested that a single-arm study would support accelerated approval for XMT- 1536, the FDA’s decision to allow IMGN to pursue this pathway offers additional validation of this strategy. The SORAYA study will enroll ~100 patients and has a primary endpoint of ORR, and the FDA has provided to IMGN that the benchmark for single-agent chemotherapy in this setting would be 12% (IMGN Investor Call Transcript). IMGN provided that the 12% ORR was based on the Phase III AURELIA and CORAIL studies that included patients both nave to and previously treated with bevacizumab. IMGN has also pointed to the response rate of 31.4% observed in 70 patients from the previously failed FORWARD-I study who met the eligibility criteria for SORAYA. The XMT-1536 Phase I expansion study in prOC is enrolling patients at the same line of therapy (1-3 priors) as the SORAYA study (as well as some patients with 4 priors, regardless of platinum- status). However, it is important (from an efficacy standpoint) to consider that these patients are not selected for NaPi2b expression (as they would likely be for an accelerated approval study)."