Loncar's Cancer Immunotherapy Index (CNCR) equal-weights about 30 U.S. and European companies producing, or are in clinical trials, for cancer immunotherapy drugs.
"I think cancer immunotherapy is a phenomenal area of science, with enormous therapeutic promise," Hougan said. He said that CNCR seems well constructed but advised against making the fund a large part of total holdings. "Niche portfolios should only represent a niche percentage of your portfolio, if any," he said.
Britt compared it to the BioShares Biotechnology Products Fund (BBP), BioShares Biotechnology Clinical Trials Fund (BBC) and ARK ETFs' Genomic Revolution Multi-Sector ETF (ARKG). "Another super-narrow niche play in biotech," Britt said. "I'd expect a volatile ride."
Biotechnology stocks have been hurt this year with the focus from regulators on drug costs and after a very hot market for biotech stocks cooled off, but CNCR launched at the bottom and, as a result, is up 16 percent since its mid-October launch, though far too short a track record to be worthy of much notice. ARKG is down near-3 percent since its 2014 launch, while BBP and BBC are up 16 percent and 8 percent, respectively, since launching in December 2014.
"This is a highly specialized sub-segment of the health-care sector, with high risks and high rewards potential," Mishra said. "Its equal weighting ensures suitable exposure to smaller companies with better growth outlook. I would watch this newly minted ETF to see if it gathers enough assets and starts trading in decent volumes, before I invest."
It charges 79 basis points and has accrued $13.6 million since launching October 13.
—By Joe D'Allegro, special to CNBC.com