4. Commitments and Contingencies

We lease our facilities in Berkeley, California (“Berkeley Lease”) and Düsseldorf, Germany (“Düsseldorf Lease”) under operating leases that expire in June 2018 and March 2023, respectively. The Berkeley Lease provides for periods of escalating rent. The total cash payments over the life of the lease are divided by the total number of months in the lease period and the average rent is charged to expense each month during the lease period. We entered into sublease agreements under the Düsseldorf Lease for a certain portion of the leased space. The sublease income is offset against our rent expense.

During September 2013, we decided not to occupy a portion of our facility in Berkeley, California. As a result, we recorded an estimated unoccupied facility expense of $0.9 million during 2013, representing the present value of the rent payments and other costs associated with the lease, net of estimated sublease income, for the remaining life of the operating lease. During the first three quarters of 2014, we reassessed our timing and ability to sublet a portion of our facility and recorded a total unoccupied facility expense of $0.4 million for the year ended December 31, 2014. In December 2014, we decided to utilize the unoccupied portion of the facility and began to recognize rent expense under the terms noted in the Berkeley Lease.

Total net rent expense related to our operating leases for the three month periods ended June 30, 2015 and 2014, was $0.5 million and $0.4 million, respectively. Total net rent expense related to our operating leases for the six month periods ended June 30, 2015 and 2014, was $1.0 million and $0.9 million, respectively. Deferred rent was $0.5 million and $0.6 million as of June 30, 2015 and December 31, 2014, respectively.

Future minimum payments under the non-cancelable portion of our operating leases at June 30, 2015, excluding payments from sublease agreements, are as follows (in thousands):

Years ending December 31,
2015 (remaining)	$	1,144
2016		2,305
2017		2,354
2018		1,299
2019		474
Thereafter		1,540
Total	$	9,116

In addition to the non-cancelable commitments included above, we have entered into contractual arrangements that obligate us to make payments to the contractual counterparties upon the occurrence of future events. In addition, in the normal course of operations, we have entered into license and other agreements and intend to continue to seek additional rights relating to compounds or technologies in connection with our discovery, manufacturing and development programs. Under the terms of the agreements, we may be required to pay future up-front fees, milestones and royalties on net sales of products originating from the licensed technologies, if any, or other payments contingent upon the occurrence of future events that cannot reasonably be estimated.

We rely on research institutions, contract research organizations, clinical investigators as well as clinical and commercial material manufacturers of our product candidates. As of June 30, 2015, under the terms of our agreements, including certain agreements relating to the ongoing Phase 3 trial of HEPLISAV-B, we are obligated to make future payments as services are provided of approximately $12.3 million through 2016. These agreements are terminable by us upon written notice. Generally, we are liable only for actual effort expended by the organizations at any point in time during the contract through the notice period.

From time to time, we are involved in claims, suits, and proceedings arising from the ordinary course of our business, including actions with respect to intellectual property claims, commercial claims, and other matters. Such claims, suits, and proceedings are inherently uncertain and their results cannot be predicted with certainty. Regardless of the outcome, such legal proceedings can have an adverse impact on us because of legal costs, diversion of management resources, and other factors. In addition, it is possible that a resolution of one or more such proceedings could result in substantial monetary damage awards, fines and penalties or orders requiring a change in our business practices, which could in the future materially and adversely affect our financial position, results of operations, or cash flows in a particular period.