Scott Bohn
Chief Development Officer and Co-Head of Life Science at Healthpeak Properties
Thanks, Pete. I'll start with an update on our life science portfolio. We had a great quarter on the leasing front with over 500,000 square feet of leases executed across the portfolio, with 87% coming in the form of new leases versus renewals. This included a 155,000 square foot lease at Vantage Phase I and 120,000 square foot lease at Oyster Point.
Additionally, we executed a 55,000 square foot full building lease at one of our Pointe Grand redevelopment buildings. The Oyster Point lease is with an existing sub-tenant that will go direct following Amgen's lease expiration at the end of 2023. The Vantage lease was with an existing tenant was tripled in size. The Pointe Grand lease was with an existing tenant growing from a 12,000 square foot space we put them in less than one year ago. These deals again highlights the benefit and competitive advantage of our local scale and ability to provide pathways to grow this fast growing life science companies.
It's important to note that we have very few lease maturities in the portfolio through year end 2024. Our Boston and San Diego portfolios are especially well positioned from a lease rollover perspective. In Boston, we only have 122,000 square foot space rolling within that window. In San Diego, we have executed up leases or LOIs of over 50% of our 2023 expirations and a minimal lease rollover in 2024.
In South San Francisco, we've been successful in backfilling the Amgen leases as they come back to us and are off to a great start at our Pointe Grand redevelopment with the previously mentioned lease execution and strong activity in other spaces. While we do have some leasing to do in South San Francisco, we view that market as the most favorable from a supply and demand perspective, so we are confident in our ability to execute. Additionally, we continue to capture significant growth from tenants within our portfolio. Of the 1.2 million square feet of leasing done this year, 91% has done with our existing tenant base. In South San Francisco alone, of the 2 million square feet of new development space we have leased in recent years, nearly 80% has been with existing portfolio tenants.
Our mark-to-market opportunity across the Life Science portfolio remains quite favorable at 26%, and our tenant credit profile continues to be resilient with over 99% net collections for the quarter, in line with historical averages. This quarter, our tenant credit profile was strengthened further as a result of the high credit lease we completed at Vantage and some large M&A deals. In South San Francisco, Global Blood Therapeutics, which started as a 76,000 square foot tenant at the [Indecipherable] and later grew to take a full 165,000 square foot building, was acquired by Pfizer for $5.4 billion. In San Diego, Turning Point Therapeutics, which executed a lease for 185,000 square feet at our Development which is set to deliver in mid-'23, was acquired for $4.1 billion by Bristol-Myers Squibb.
Now looking at rent growth demand and new supply. In South San Francisco, we've seen rental rates up in the mid single-digits year-to-date with approximately 2 million square feet of active demand. San Diego market rents are up low to mid single-digits for the year and active demand is 1 million square feet. Market rents are up mid single-digits in Boston with active demand of approximately 2.2 million square feet.
While the demand numbers have come off their record highs over the past few years, they are in line when comparing to pre-pandemic levels and the markets remained strong with low single-digit vacancy rates. Even more so when the markets tighten, Healthpeak and the other incumbent life science landlords will continue to capture outsized percentages of the leasing activity due to having scale and tenant relationships that new entrants are unable to match.
On the supply side, we're seeing ground-up and conversion projects being delayed or put on hold as a result of higher development costs and potentially more impactful the significant interest rate increases that have made many levered projects economically and feasible. As we discussed, our team tracks every ongoing and proposed project within our clusters. And the competitive supply we're tracking over the next three plus years is lower today than it was six months ago.
Next, I'll touch on the Life Science lending environment. We've seen a number of tenants raised capital via secondary equity offerings, debt offerings and private placements. We've also seen our tenants entered into partnerships or license agreements with pharma as well as some large M&A transactions, as I mentioned earlier. VC funding during the third quarter has already surpassed 2018 and 2019 full year levels and is on pace to match full year 2020. Public biopharma R&D spending through the first half of the year was $77 billion, which is 8% higher than the first half of last year and is on pace to challenge 2021 as the highest R&D spending year ever.
Now turning to development. Our $1 billion active life science developments are 81% pre-leased and continue to progress on time and on budget with a blended yield of approximately 7.5%. Once stabilized, we expect an incremental $75 million of cash NOI from these projects. All developments are fully bought out under GMP, effectively locking in our yields.
In South San Francisco, the general plan was passed by the City Council in October. The new general plan includes the ability to develop higher densities in certain parts of the city, including our Vantage land. With the revised zoning, we expect to entitle the balance of our Vantage project for upwards of 1.3 million square feet, which, coupled with our 343,000 square foot Phase I that is currently under construction, will bring the total project to nearly 1.7 million square feet upon completion, allowing us to build on our number one market share in South San Francisco.
Lastly, an update on construction costs. The extreme pricing volatility that the market has seen recently is beginning to calm. We're seeing above average price increases on some materials, but overall escalations have come back down to the low teens year-over-year, well below the 20% year-over-year numbers we discussed in prior quarters. Looking forward, we expect to see cost increases to be more in the 6% to 8% range over the next 12 months. We continue to see long and, at times, unpredictable lead times for items like generators and mechanical equipment, but our teams have done an excellent job procuring these long lead materials early and managing supply chain challenges to ensure projects are being delivered on time and on budget.
To wrap up, while the overall economic backdrop has caused demand to return to more normalized levels, our Life Science portfolio remains extremely well positioned to post strong internal growth, given our minimal near-term maturities, continued focus on the core markets and strong mark-to-market opportunities across the portfolio.
With that, operator, let's open up the line for Q&A.
